100 ~I:ARS
A PRO\T_NPARTNERSHIP
M alilla 011
6th Edition A, W, Drews, editor
Manual on Hydrocarbon
Analysis: 6th E...
703 downloads
8194 Views
64MB Size
Report
This content was uploaded by our users and we assume good faith they have the permission to share this book. If you own the copyright to this book and it is wrongfully on our website, we offer a simple DMCA procedure to remove your content from our site. Start by pressing the button below!
Report copyright / DMCA form
100 ~I:ARS
A PRO\T_NPARTNERSHIP
M alilla 011
6th Edition A, W, Drews, editor
Manual on Hydrocarbon
Analysis: 6th Edition A. W. Drews editor
ASTM Manual Series: MNL3 ASTM Stock #: MNL3
100 Barr Harbor Drive, West Conshohocken, PA 19428-2959
Library of Congress Cataloging-in-Publication Data Manual on hydrocarbon analysis--6th ed./A. W. Drews, editor (ASTM manual series: MNL 3) ASTM Stock #: MNL3 Includes bibliographical references and index ISBN 0-8031-2080-X 1. Petroleum productswAnalysis. 2. Hydrocarbons--Analysis. I. Drews, A.W. II. Series. TP691.M358 1998 665.5---dc21 98-25886 CIP
Copyright © 1998 by the AMERICAN SOCIETY FOR TESTING AND MATERIALS, West Conshohocken, PA. All rights reserved. This material may not be reproducedor copied, in whole or in part, in any printed, mechanical, electronic, film, or other distribution and storage media, without the written consent of the publisher.
Photocopy Rights Authorization to photocopy items for internal, personal, or educational classroom use, or the internal, personal, or educational classroom use of specific clients, is granted by the American Society for Testing and Materials (ASTM) provided that the appropriate fee is paid to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923; Tel: 508750-8400; online: http://www.copyright.comL
NOTE: This manual does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this manual to establish appropriate safety and health practices and determine the applicability of regulatory limitations pnor to use.
NOTE: The Society is not responsible, as a body, for the statements and opinions advanced in this publication.
Printed in Baltimore June 1998
Foreword THIS SIXTHEDITIONOF THE Manual on Hydrocarbon Analysis, sponsored by ASTM Committee D02 on Petroleum Products and Lubricants, has been expanded even further than the fifth edition. First appearing in 1963 as STP332, this manual was updated by Committee D02 in 1968, 1977, 1987, and 1992. In this 1998 edition, Part 2 has been expanded to include 26 additional ASTM test methods. Furthermore, the number of chapters has been increased from five to seven through the creation of a separate chapter, "Analysis of Kerosine, Diesel and Aviation Turbine Fuels," and a totally new chapter, "Analysis of Waxes." For additional information on the significance of tests, the reader is encouraged to consult the
Industry and governmental requirements for accurate, more detailed data in a shorter time frame have resulted in substantial method changes. Rapid instrumental techniques, incorporating automatic sampling and on-line instrumentation, are replacing many of the time-honored empirical and, even, wet-chemical procedures. Yet many of the established techniques are still utilized and, thus, they are included in this manual along with the methods that are replacing them. It is exciting to speculate what further changes will occur before issuance of the next edition. Publication of this manual would not have been possible without the efforts of the ASTM staff, the authors--N. G. Johansen, J. M. McCann, G. Hemighaus, T. M. Warne, A. J. Lubeck, A. D. Barker, C.H. Pfeiffer, the reviewers--S. E. Litka and N. D. Smith, and to L. A. Drews for collating, formatting, and reviewing the texts. I express my appreciation to all those who made this sixth edition a reality.
Manual on Significance of Tests for Petroleum Products, 6th Edition. Methodology is changing quickly, requiring revisions to existing methods and the standardization of new ones. The impact of computerization and microprocessors cannot be overemphasized. Modern data-handling capabilities allow highly detailed compositional analyses to be performed that were once only a vision. Some of these resulting methods have been standardized; others will follow rapidly as experience is gained.
A. W. Drews, editor Subcommittee D02.04 on Hydrocarbon Analysis
ool
Ul
Purpose of Manual THE PURPOSEOF THIS MANUALis two-fold. The seven imroductory chapters provide the analyst with a comprehensive overview of current practices and tests relating to the analysis of hydrocarbons. The accompanying collection of ASTM test methods furnishes a convenient reference within a single volume. It is hoped that this combination will provide the reader with a clearer understanding and appreciation of this diversified subject.
iv
Contents INTRODUCTORY INFORMATION
Introduction Table 1--Summary of Product Types Produced from Petroleum Table 2--Summary of ASTM Test Methods (by subject) Table 3--Number of Isomeric Paraffins Table 4--Summary of Hydrocarbon Types in Petroleum Fractions
3 4 5 11 11
PART 1--DISCUSSIONOF ANALYSES BY PRODUCT TYPE Analysis of Cs and Lighter Hydrocarbons by N. G. J o h a n s e n Introduction Current Practices Future Trends 2 Analysis of Gasoline a n d Other Light Distillate Fuels by J. M. M c C a n n Introduction Current Practices Future Trends
Analysis o f Kerosine, Diesel, a n d Aviation T u r b i n e Fuel by G. H e m i g h a u s Introduction Current Practices Future Trends 4 Analysis of Viscous Oils by T. M. W a r n e Introduction Current Practices Future Trends
15 15 15 16 18 18 18 20
22 22 22 23 25 25 25 30
Analysis o f Waxes by A. D. B a r k e r Introduction Current Practices Future Trends
31 31 31 32 34 34 35 39
6 Analysis o f Crude Otis by A. J. L u b e c k Introduction Current Practices Future Trends Analysis o f A r o m a t i c Hydrocarbons by C. H. P f e i f f e r Introduction Current Practices Future Trends V
41 41 41 42
vi
CONTENTS PART 2 - - A S T M
TEST METHODS
The test methods in this section are arranged in alphanumeric sequence. The page numbers apply only to this manual and not to the standard documents as they appear in the annual ASTM Book of Standards. See Table 2 for a list of test methods by subject. The following is a list of all test methods included in Part 2. It includes all test methods referenced in the seven chapters except as indicated in the chapters. It does not include all of the test methods cited in Table 2. D5 D36 D56 D86 D87 D96 D97 D127 D130 D 189 D287 D323 D341 D445 D447 D473 D482 D524 D611 D664 D721 D848 D849 D850 D852 D853 D972 D976 D 1078 D1133 D 1142 D 1159 Dl160 D 1209 D1218 D1250 D1265 D1298 D1319 D1322 D1492 D1552 D1685 D1747 D1840
Test Method for Penetration of Bituminous Materials Test Method for Softening Point of Bitumen (Ring-and-Ball Apparatus) Test Method for Flash Point by Tag Closed Tester Test Method for Distillation of Petroleum Products at Atmospheric Pressure Test Method for Melting Point of Petroleum Wax (Cooling Curve) Test Method for Water and Sediment in Crude Oil by Centrifuge Method (Field Procedure) Test Method for Pour Point of Petroleum Oils Test Method for Drop Melting Point of Petroleum Wax Including Petrolatum Test Method for Detection of Copper Corrosion from Petroleum Products by the Copper Strip Tarnish Test Test Method for Conradson Carbon Residue of Petroleum Products Test Method for API Gravity of Crude Petroleum and Petroleum Products (Hydrometer Method) Test Method for Vapor Pressure of Petroleum Products (Reid Method) Viscosity-Temperature Charts for Liquid Petroleum Products Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and the Calculation of Dynamic Viscosity) Test Method for Distillation of Plant Spray Oils Test Method for Sediment in Crude Oils and Fuels Oils by the Extraction Method Test Method for Ash from Petroleum Products Test Method for Ramsbottom Carbon Residue of Petroleum Products Test Methods for Aniline Point and Mixed Aniline Point of Petroleum Products and Hydrocarbon Solvents Test Method for Acid Number of Petroleum Products by Potentiometric Titration Test Method for Oil Content of Petroleum Waxes Test Method for Acid Wash Color of Industrial Aromatic Hydrocarbons Test Method for Copper Strip Corrosion of Industrial Aromatic Hydrocarbons Test Method for Distillation of Industrial Aromatic Hydrocarbons and Related Materials Test Method for Solidification Point of Benzene Test Method for Hydrogen Sulfide and Sulfur Dioxide Content (Qualitative) of Industrial Aromatic Hydrocarbons Test Method for Evaporation Loss of Lubricating Greases and Oils Test Method for Calculated Cetane Index of Distillate Fuels Test Method for Distillation Range of Volatile Organic Liquids Test Method for Kauri-Butanol Value of Hydrocarbon Solvents Test Method for Water Vapor Content of Gaseous Fuels by Measurement of Dew-Point Temperature Test Method for Bromine Number of Petroleum Distillates and Commercial Aliphatic Olefins by Electrometric Titration Test Method for Distillation of Petroleum Products at Reduced Pressure Test Method for Color of Clear Liquids (Platinum-Cobalt Scale) Test Method for Refractive Index and Refractive Dispersion of Hydrocarbon Liquids Guide for Petroleum Measurement Tables Practice for Sampling Liquefied Petroleum (LP) Gases (Manual Method) Practice for Density, Relative Density (Specific Gravity) or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method Test Method for Hydrocarbon Types in Liquid Petroleum Products by Fluorescent Indicator Adsorption Test Method for Smoke Point of Aviation Turbine Fuels Test Method for Bromine Index of Aromatic Hydrocarbons by Coulometric Titration Test Method for Sulfur in Petroleum Products (High-Temperature Method) Test Method for Traces of Thiophene in Benzene by Spectrophotometry Test Method for Refractive Index of Viscous Materials Test Method for Naphthalene Hydrocarbons in Aviation Turbine Fuels by Ultra Violet Spectrophotometry
47 50 54 64 77 80 87 95 97 103 109 112 120 126 134 137 141 144 152 159 166 172 175 177 182 184 186 190 193 200 202 213 222 240 243 247 249 252 257 263 269 272 277 280 284
CONTENTS D1945 D1946 D1988 D2007 D2158 D2163 D2171 D2306 D2360 D2386 D2425 D2426 D2500 D2501 D2502 D2503 D2504 D2505 D2549 D2593 D2597 D2622 D2650 D2710 D2712 D2784 D2786 D2878 D2887 D2892 D3054 D3120 D3205 D3227 D3230 D3235 D3239 D3241 D3246 D3279 D3524 D3606 D3700 D3701
Test Method for Analysis of Natural Gas by Gas Chromatography Practice for Analysis of Reformed Gas by Gas Chromatography Test Method for Mercaptans in Natural Gas Using Length-of-Stain Detector Tubes Test Method for Characteristic Groups in Rubber Extender and Processing Oils and Other Petroleum-Derived Oils by Clay-Gel Absorption Chromatographic Method Test Method for Residues in Liquefied Petroleum (LP) Gases Test Method for Analysis of Liquefied Petroleum (LP) Gases and Propene Concentrates by Gas Chromatography Test Method for Viscosity of Asphalts by Vacuum Capillary Viscometer Test Method for C8 Aromatic Hydrocarbon Analysis by Gas Chromatography Test Method for Trace Impurities in Monocyclic Aromatic Hydrocarbons by Gas Chromatography Test Method for Freezing Point of Aviation Fuels Test Method for Hydrocarbon Types in Middle Distillates by Mass Spectrometry Test Method for Butadiene Dimer and Styrene in Butadiene Concentrates by Gas Chromatography Test Method for Cloud Point of Petroleum Oils Test Method for Calculation of Viscosity-Gravity Constant (VGC) of Petroleum Oils Test Method for Estimation of Molecular Weight (Relative Molecular Mass) of Petroleum Oils from Viscosity Measurements Test Method for Relative Molecular Mass (Molecular Weight) of Hydrocarbons by Thermoelectric Measurement of Vapor Pressure Test Method for Noncondensable Gases in C2 and Lighter Hydrocarbon Products by Gas Chromatography Test Method for Ethylene, Other Hydrocarbons, and Carbon Dioxide in High-Purity Ethylene by Gas Chromatography Test Method for Separation of Representative Aromatics and Nonaromatics Fractions of High Boiling Oils by Elution Chromatography Test Method for Butadiene Purity and Hydrocarbon Impurities by Gas Chromatography Test Method for Analysis of Demethanized Hydrocarbon Liquid Mixtures Containing Nitrogen and Carbon Dioxide by Gas Chromatography Test Method for Sulfur in Petroleum Products by X-Ray Spectrometry Test Method for Chemical Composition of Gases by Mass Spectrometry Test Method for Bromine Index of Petroleum Hydrocarbons by Electrometric Titration Test Method for Hydrocarbon Traces in Propylene Concentrates by Gas Chromatography Test Method for Sulfur in Liquefied Petroleum Gases (Oxy-Hydrogen Burner or Lamp) Test Method for Hydrocarbon Types Analysis of Gas-Oil Saturates Fractions by High Ionizing Voltage Mass Spectrometry Test Method for Estimating Apparent Vapor Pressures and Molecular Weights of Lubricating Oils Test Method for Boiling Range Distribution of Petroleum Fractions by Gas Chromatography Test Method for Distillation of Crude Petroleum (15-Theoretical Plate Column) Test Method for Purity and Benzene Content of Cyclohexane by Gas Chromatography Test Method for Trace Quantities of Sulfur in Light Liquid Petroleum Hydrocarbons by Oxidative Microcoulometry Test Method for Viscosity of Asphalt with Cone and Plate Viscometer Test Method for Mercaptan Sulfur in Gasoline, Kerosine, Aviation Turbine, and Distillate Fuels (Potentiometric Method) Test Method for Salts in Crude Oil (Electrometric Method) Test Method for Solvent Extractables in Petroleum Waxes Test Method for Aromatic Types Analysis of Gas-Oil Aromatic Fractions by High Ionizing Voltage Mass Spectrometry Test Method for Thermal Oxidation Stability of Aviation Turbine Fuels (JFTOT Procedure) Test Method for Sulfur in Petroleum Gas by Oxidative Microcoulometry Test Method for Heptane Insolubles Test Method for Diesel Fuel Diluent in Used Diesel Engine Oils by Gas Chromatography Test Method for the Determination of Benzene and Toluene in Finished Motor and Aviation Gasoline by Gas Chromatography Practice for Containing Hydrocarbon Fluid Samples Using a Floating Piston Cylinder Test Method for Hydrogen Content of Aviation Turbine Fuels by Low Resolution Nuclear Magnetic Resonance Spectrometry
vii 287 302 307 311 318 322 327 334 337 342 346 352 355 358 361 365 368 373 379 385 392 402 406 413 420 426 432 439 444 455 484 488 494 498 503 508 514 527 538 545 548 552 559 563
viii
CONTENTS
D3710 D3760 D3797 D3798 D3961 D4006 D4007 D4045 D4052 D4053 D4057 D4177 D4291 D4294 D4307 D4367 D4377 D4419 D4423 D4424 D4492 D4530 D4534 D4628 D4629 D4735 D4737 D4808 D4810 D4815 D4864 D4888 D4927 D4928 D4929 D4951 D4953 D5002 D5060 D5134 D5135 D5185
D5186 D5190 D5191
Test Method for Boiling Range Distribution of Gasoline and Gasoline Fractions by Gas Chromatography Test Method for Analysis of Isopropyl Benzene (Cumene) by Gas Chromatography Test Method for Analysis of o-Xylene by Gas Chromatography Test Method for Analysis of p-Xylene by Gas Chromatography Test Method for Trace Quantities of Sulfur in Liquid Aromatic Hydrocarbons by Oxidative Microcoulometry Test Method for Water in Crude Oil by Distillation Test Method for Water and Sediment in Crude Oil by the Centrifuge Method (Laboratory Procedure) Test Method for Sulfur in Petroleum Products by Hydrogenolysis and Rateometric Colorimetry Test Method for Density and Relative Density of Liquids by Digital Density Meter Test Method for Benzene in Motor and Aviation Gasoline by Infrared Spectroscopy Practice for Manual Sampling of Petroleum and Petroleum Products Practice for Automatic Sampling of Petroleum and Petroleum Products Test Method for Trace Ethylene Glycol in Used Engine Oil Test Method for Sulfur in Petroleum Products by Energy-Dispersive X-Ray Fluorescence Spectroscopy Practice for Preparation of Liquid Blends for Use as Analytical Standards Test Method for Benzene in Hydrocarbon Solvents by Gas Chromatography Test Method for Water in Crude Oils by Potentiometric Karl Fischer Titration Test Method for Measurement of Transition Temperatures of Petroleum Waxes by Differential Scanning Calorimetry Test Method for Determination of Carbonyls in C4 Hydrocarbons Test Method for Butylene Analysis by Gas Chromatography Test Method for Analysis of Benzene by Gas Chromatography Test Method for Determination of Carbon Residue (Micro Method) Test Method for Benzene Content of Cyclic Products by Gas Chromatography Test Method for Analysis of Barium, Calcium, Magnesium and Zinc in Unused Lubricating Oils by Atomic Absorption Test Method for Trace Nitrogen in Liquid Petroleum Hydrocarbons by Syringe/Inlet Oxidative Combustion and Chemiluminescence Detection Test Method for Determination of Trace Thiophene in Refined Benzene by Gas Chromatography Test Method for Calculated Cetane Index by Four Variable Equation Test Method for Hydrogen Content of Light Distillates, Middle Distillates, Gas Oils, and Residua by Low Resolution Nuclear Magnetic Resonance Spectroscopy Test Method for Hydrogen Sulfide in Natural Gas Using Length-of-Stain Detector Tubes Test Method for Determination of MTBE, ETBE, TAME, DIPE, tertiary-Amyl Alcohol and Cl to C4 Alcohols in Gasoline by Gas Chromatography Test Method for Determination of Traces of Methanol in Propylene Concentrates by Gas Chromatography Test Method for Water Vapor in Natural Gas Using Length-of-Stain Detector Tubes Test Method for Elemental Analysis of Lubricant and Additive Components--Barium, Calcium, Phosphorus, Sulfur and Zinc by Wavelength-Dispersive X-Ray Fluorescence Spectroscopy Test Method for Water in Crude Oils by Coulometric Karl Fischer Titration Test Method for Determination of Organic Chloride Content in Crude Oil Test Method for Determination of Additive Elements in Lubricating Oils by Inductively Coupled Plasma Atomic Emission Spectrometry Test Method for Vapor Pressure of Gasoline and Gasoline-Oxygenate Blends (Dry Method) Test Method for Density and Relative Density of Crude Oils by Digital Density Analyzer Test Method for Determining Impurities in High-Purity Ethylbenzene by Gas Chromatography Test Method for Detailed Analysis of Petroleum Naphthas Through Nonane by Capillary Gas Chromatography Test Method for Analysis of Styrene by Capillary Gas Chromatography Test Method for Determination of Additive Elements, Wear Metals, and Contaminants in Used Lubricating Oils and Determination of Selected Elements in Base Oils by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) Test Method for the Determination of the Aromatic Content and Polynuclear Aromatic Content of Diesel Fuels and Aviation Turbine Fuels by Supercritical Fluid Chromatography Test Method for Vapor Pressure of Petroleum Products (Automatic Method) Test Method for Vapor Pressure of Petroleum Products (Mini Method)
567 578 582 586 590 596 606 617 621 625 628 646 670 673 676 679 684 688 691 694 696 700 705 708 712 716 720 723 728 731 739 744 747 753 760 766 771 778 783 786 797 800
806 811 816
CONTENTS D5194 D5234 D5236 D5273 D5274 D5287 D5291 D5292 D5303 D5307 D5384 D5386 D5442 D5443 D5453 D5454 D5482 D5503 D5504 D5580 D5599 D5622 D5623 D5708 D5713 D5762 D5769 D5776 D5799 D5808 D5842 D5845 D5853 D5863 D5917 D5986 D6069 D6144 D6159
Test Method for Trace Chloride in Liquid Aromatic Hydrocarbons Guide for Analysis of Ethylene Product Test Method for Distillation of Heavy Hydrocarbon Mixtures (Vacuum Potstill Method) Guide for Analysis of Propylene Concentrates Guide for Analysis of 1,3-Butadiene Product Practice for Automatic Sampling of Gaseous Fuels Test Method for Instrumental Determination of Carbon, Hydrogen, and Nitrogen in Petroleum Products and Lubricants Test Method for Aromatic Carbon Content of Hydrocarbon Oils by High Resolution Nuclear Magnetic Resonance Spectroscopy Test Method for Trace Carbonyl Sulfide in Propylene by Gas Chromatography Test Method for Determination of the Boiling Range Distribution of Crude Petroleum by Gas Chromatography Test Method for Chlorine in Used Petroleum Products (Field Test Kit Method) Test Method for Color of Liquids Using Tristimulus Colorimetry , Test Method for Analysis of Petroleum Waxes by Gas Chromatdgraphy Test Method for Paraffin, Naphthene and Aromatic Hydrocarbon Type Analysis in Petroleum Distillates Through 200°C by Multi-Dimensional Gas Chromatography Test Method for Determination of Total Sulfur in Light Hydrocarbons, Motor Fuels, and Oils by Ultraviolet Fluorescence Test Method for Water Vapor Content of Gaseous Fuels Using Electronic Moisture Analyzers Test Method for Vapor Pressure of Petroleum Products (Mini Method-Atmospheric) Practice for Natural Gas Sample-Handling and Conditioning Systems for Pipeline Instrumentation Test Method for Determination of Sulfur Compounds in Natural Gas and Gaseous Fuels by Gas Chromatography and Chemiluminescence Test Method for Determination of Benzene, Toluene, Ethylbenzene, p/m-Xylene, o-Xylene, C9 and Heavier Aromatics, and Total Aromatics in Finished Gasoline by Gas Chromatography Test Method for Determination of Oxygenates in Gasoline by Gas Chromatography and Oxygen Selective Flame Ionization Detection Test Method for the Determination of Total Oxygen in Gasoline and Methanol Fuels by Reductive Pyrolysis Test Method for Sulfur Compounds in Light Petroleum Liquids by Gas Chromatography and Sulfur Selective Detection Test Method for Determination of Nickel, Vanadium, and Iron in Crude Oils and Residual Fuels by Inductively Coupled Plasma (ICP) Atomic Emission Spectrometry Test Method for Analysis of High Purity Benzene for Cyclohexane Feedstock by Capillary Gas Chromatography Test Method for Nitrogen in Petroleum and Petroleum Products by Boat-Inlet Chemiluminescence Test Method for Determination of Benzene, Toluene and Total Aromatics in Finished Gasoline by Gas Chromatography/Mass Spectrometry Test Method for Bromine Index of Aromatic Hydrocarbons by Electrometric Titration Test Method for Determination of Peroxides in Butadiene Test Method for Determining Organic Chloride in Aromatic Hydrocarbons and Related Chemicals by Microcoulometry Practice for Sampling and Handling of Fuels for Volatility Measurement Test Method for the Determination of MTBE, ETBE, TAME, DIPE, Methanol, Ethanol and tertButanol in Gasoline by Infrared Spectroscopy Test Method for Pour Point of Ct:ude Oils Test Method for Determination of Nickel, Vanadium, Iron, and Sodium in Crude Oils and Residual Fuels by Flame Atomic Absorption Spectrometry Test Method for Trace Impurities in Monocyclic Aromatic Hydrocarbons by Gas Chromatography and External Calibration Test Method for the Determination of Oxygenates, Benzene, Toluene, Cs-C12 Aromatics and Total Aromatics in Finished Gasolines by Gas Chromatography/Fourier Transform Infrared Spectroscopy (GC/FTIR) Test Method for Trace Nitrogen in Aromatic Hydrocarbons by Oxidative Combustion and Reduced Pressure Chemiluminescence Detection Test Method for Analysis of AMS (ct-Methylstyrene) by Gas Chromatography Test Method for Determination of Hydrocarbon Impurities in Ethylene by Gas Chromatography
ix 821 824 826 842 845 847 852 857 864 870 877 88O 883 890 900 906 908 912 917 922 931 939 943 948 953 956 961 972 975 977 981 988 993 1000 1005 1011
1025 1030 1034
x
CONTENTS
D6160 D6212
Test Method for Determination of Polychlorinated Biphenyls (PCBs) in Waste Materials by Gas Chromatography Test Method for Total Sulfur in Aromatic Compounds by Hydrogenolysis and Rateometric Colorirnetry
1039 1054
Introductory Information
Introduction
THE PETROLEUMANALYSTis a problem solver and, as such, is constantly required to make method choices. In the past, two questions were most frequently associated with the method selection process. • What properties can be determined to solve a particular production problem? • What methods are appropriate to determine a specific property? Now the analyst is faced with additional complications. These include the need to produce results faster, in more detail, at lower concentration levels; to reduce costs (usually in the form of analyst labor); and to provide higher-quality results. In addition, federal and state regulations, particularly on spark-ignition engine fuels, influence method choice. Thus, method choice is now even more difficult. Fortunately, technology has advanced dramatically. Instrumental techniques have prospered and continue to improve rapidly. Gas chromatography, long a mainstay, is using faster, more efficient columns along with element-specific detectors. Furthermore, hyphenated techniques such as gas chromatography-mass spectrometry (GC/MS) and liquid chromatography-mass spectrometry (LC/MS) are providing separations that were once only a vision. Other spectrometric techniques--near infrared (NIR), Fourier transform infrared (FTIR), and nuclear magnetic resonance (NMR), to name a few, are being utilized on-line virtually unattended to provide real-time data. Nevertheless, the method of choice will still depend on the boiling range (or carbon number) of the sample to be analyzed, and, following this, the resources available to the analyst. Therefore, in this manual, the hydrocarbons, along with their associated methods, are discussed according to boiling range. The first five chapters of this manual are arranged beginning with "Analysis of C5 and Lighter Hydrocarbons," followed by "Analysis of Gasoline and Other Light Distillate Fuels," "Analysis of Kerosine, Diesel, and Aviation Turbine Fuel," "Analysis of Viscous Oils," and "Analysis of Waxes." Chapter 6, "Analysis of Crude Oils," deals with the total span of compounds, from gases to non-distillables. Chapter 7, "Analysis of Aromatics Hydrocarbons," is a special case that discusses a particular class of compounds that has increasingly gained importance in octane enhancing and, particularly, in petrochemicals.
Table 1 shows the carbon number range and boiling points (of normal paraffins) for some of the more common petroleum products of commerce. ASTM methods that may be applied to these boiling ranges are shown in Table 2. These tables are provided as an overview of the complex hydrocarbon analysis field; they do not show all of the methods that might be applicable. Details on many of these analytical methods, as well as techniques and procedures under development, are discussed in the appropriate chapters. Crude petroleum and fractions (or products) obtained from it contain a complex variety of compounds. It is interesting to note that as the number of carbon atoms increases, the possible complexity of petroleum mixtures also rapidly increases (see Table 3). Consequently, detailed analysis of the higher boiling fractions becomes increasingly difficult. Instrumental techniques have improved this situation, and the data being obtained provide extremely valuable input for the design, control, and evaluation of petroleum processes. Traditionally, however, these techniques were not available, It was necessary (and in many cases, satisfactory) to empirically determine specific physical properties that could be related to product quality and process control. Although the number of these tests is diminishing, many of them are still in common use. Some appear in this text because product specifications reference them and some referee methods still utilize the more basic testing procedures. Additionally, "classes" or types of hydrocarbons were and still are determined based on the capability to isolate them by separation techniques. The four types usually sought are paraffins, olefins, naphthenes, and aromatics. Paraffinic hydrocarbons include both normal and branched alkanes. Olefins refer to normal and branched alkenes that contain one or more double or triple carbon-carbon bonds. Naphthene (not to be confused with "naphthalene") is a term of the petroleum industry that refers to the saturated cyclic hydrocarbons or "cycloalkanes." Finally, aromatics include all hydrocarbons containing one or more rings of the benzenoid structure. These general hydrocarbon classifications are complicated by many combinations of the above types, for example, olefinic aromatics (styrene) or alkylbenzenes (cumene). Table 4 presents a summary of the hydrocarbon types usually found in specific petroleum fractions.
4
MANUAL ON HYDROCARBON ANALYSIS
A
A~
V
A
V
v
V
i
V
~+~ V
~+
"7
el
wg~
I r
INTRODUCTORY INFORMATION Table 2--Summary of ASTM Test Methods Number of CarbonAtoms Boiling Rangeof Normal Paraffmsat 760 mm Hg, °C
C1-C2 -161 to -89
C:Cs -42to +36
Physical Methods D5, Penetration of bituminous materials D36, Ring and ball softening point D56, Flash by tag closed cup tester D86, Distillation of petroleum products D87, Melting point of wax
Co.-CIo 6 9 t o 174
X X
X X
X
X X
X X X
X
X X X X X
X
X
X
X X X
X X X
X
X X
X X
X
X
X
X
X
X
D852, Solidification point of benzene D972, Evaporation losses of greases & oils DlOIS, Purity from freezing point DI016, Purity from freezing point D 1078, Distillation of volatile organic liquids
D1837, Volatility of LP gases D2158; Residue in LP gases D2171, Viscosity of asphalts D2386, Freezing point of aviation fuels D2500, Cloud point of peltoleum oils
>(2)) >355
X
13482, Ash from petroleum products D524, Ramsbottom carbon residue D611, Aniline point D721, Oil content of petroleura waxes D850, Distillation of industrial aromatics
D 1322, Smoke point of aviation turbine fuels D 1493, Solidification point of organic chemicals D 1657, Relative density of light hydrocarbons D 1747, Refractive index of viscous materials D 1807, Refractive index of insulating oils
X
X X
D287, API gravity by hydrometer D323, Vapor pressure (Reid method) D445, Kinematic viscosity D447, Distillation of plant spray oils D473, Sediment by extraction
Water vapor of gaseous fuels Distillation at reduced pressure Refractive index & dispersion Vapor pressure of LP gases Relative density of liquids
C~s-Czo 287 to 343
X X
D92, Flash and fire Cleveland open cup D93, Flash and fire by Pensky-Martens closed cup D97, Pour point D 127, Melting point of wax D189, Couradson carbon residue
D1142, D 1160, D 1218, D1267, D 1298,
CH-CI~ 196 to 270
X
x
X X X
X
X
X
X
X
X
X
X
X
X X
X
X
X X X X
I
X X
X X X X
X X
X
5
6
MANUAL ON HYDROCARBON ANALYSIS T a b l e 2 - continued Number of Carbon Atoms Boiling Range of Normal Paraffins at 760 nun Hg, °C
CI-C2 -161 to -89
C3-C~ -42to +36
D2503, Molecular weight D2533, Vapor-liquid ratio of gasoline D2892, Distillation of crude oil D3205, Viscosity of asphalt (cone & plate) D3279, n-Heptane insolubles
C6-C1o 6 9 t o 174
X X
X X X X
D4809, Precise heat of combustion D4953, Vapor pressure of gasoline oxygenate blends D5002, Density of erude oil D5 ! 90, Vapor pressure (automatic method) D5 ! 91, Vapor pressure (mini method)
X X
>C~ >355
X
X
X
X X X
X X X X X
X X X
X
X
X
X
X X
X X
D5236, Distillation of heavy oils D5482, Vapor pressure of petroleum products D5853, Pour point of crude oils
X X
Correlative Methods D341, Viscosity-temperature charts for hydrocarbons D976, Calculation of octane index of distillate fuels D 1250, Petroleum measurement tables D2270, Calculation of viscosity index D250 !, Viscosity-gravityconstant of oils
X
X
X X
X X
X X
X
X X X
X X X X X
X
X
X
X X
X
X
X X
Liquid Chromatographic Methods D 1319, Hydrocarbon types by FIA D2007, Rubber extender & processing oils D2549, Aromatics & nonaromatics in distillates D5186, Aromatics in diesel fuel by SFC X X X
X X
X
D3343, Hydrogen content of aviation gasoline D4529, Estimation of heat of combustion of aviation fuels D4737, Calculated oetane index
Gas Chromatographic Methods D1945, Analysis of natural gas D1946, Analysis of reformed gas D2163, LP gases & propylene concentrates D2268, High-purity heptane & isooctane D2306, Xylene isomers in xylene
X
Ct,-C2o 287 to 343
X
D3828, Flash point by Seta flash closed tester D4052, Density by digital density meter D4206, Sustained burning test by Seta flash D4207, Sustained burning test by wick method D4530, Micro carbon residue
D2502, Molecular weight of oils D2598, Physical properties of LP gases D2889, Calculation of true vapor pressure D3238, Carbon distribution & structure analysis, n-d-M D3338, Estimation of heat of combustion of aviation fuels
Cu-C~5 196 to 270
X X X
X X X
X
X
X
X X X X X
X X X X
X X
INTRODUCTORY INFORMATION Table 2 - continued Number of Cazbon Atoms
BoilingRange of NormalPaxaffmsat 760 mm Hg, °C
CcC~
C~'Cs
-161to -89
-42to +36
Cs-Clo
69to 174
C.-Cis 196 to 270
C,6-C~ 287 to 343
>C= >355
X
X
X
X X
X
....,
D2360, D2426, D2427, D2504, D2505, ,,
Trace impurities in aromatics Butadiene dimer & styrene C2-C5 in gasoline Nonenndensibles in C3 & lighter Analysis of high-purity ethylene
X X X X
X X X
X
,
D2593, D2597, D2712, D2820, D2887,
Butadiene purity and hydrocarbon impurities Natural gas-liquid mixtures Hydrocarbon Iraces in propylene C,-C~ hydrocarbons in atomosphere Boiling range distribution of petroleum fractions
D3054, D3524, D3525, D3606, D3710,
Cyolohexane purity & benzene content Diesel fuel in used iubc oils Gasoline diluent m engine oils Benzene & toluene in gasoline Boiling range distribution of gasoline
D3760. D3797, D3798. D3962, D4367,
Analysis of isopropylbenzene Purity of o-xylene Purity of p-xylene Analysis of styrene Benzene content of solvents
D4420, D4424, D4492, D4534, D4626,
Aromatics in finished gasolines Butane-butene mixtures Purity of benzene Benzene content of cyclic hydrocarbons Calculation of response factors
D4735. IM815, D4864, D5060, D5134, D5135,
Trace thiophene in benzene Alcohols and MTBE in gasoline Methanol in propylene Impurities in ethylbenzene Analysis of naphthas Analysis of styrene
D5303, D5307, D5442, D5443, D5504,
Trace COS in propylene Boiling range distribution of crude oil Petroleum wax Hydrocarbon types Sulfur compounds by GC & chemiluminescence
D5580, Aromatics in gasoline D5599,'Oxygenates in gasoline by GC & OFID D5623, Sulfur compounds by GC & sulfur selective detector D5713, Benzene purity D5769, Aromatics in gasoline by GC-MS
X X X
X X X X X
X
X X
X X
X X X
X
X X X X X X X
X
X
X X X
X
X
X
X
X X
X X
X X X X X X X
X X
X
X
X X X X X X X
X
7
8
MANUAL ON HYDROCARBON A N A LYSI S T a b l e 2 - continued Number o f Carbon Atoms Boiling Range o f Normal Paraffins at 760 m m Hg, °C
D5917, Trace impurities in aromatics D5986, Oxygenates and aromatics in gasoline by GC/FTIR I)6144, Analysis of cx-methylstyrene 136159, Impurities in ethylene D6160, PCBs in waste material Spectroscopic Methods D 1840, Naphthalenes in aviation turbine fuels D2425, Hydrocarbon types in distillates by MS D2650, Chemical composition of gases by MS D2786, Analysis of gas-oil saturate fractions by MS D2789, Hydrocarbon types in gasoline by MS
C~-C2 -161 to -89
C:Cs -42 to +36
D 1492, Bromine index of aromatics D2710, Bromine index by electrometric titration D4423, Carbonyl in C4 hydrocarbons D5776, Bromine index D5799, Peroxides in butadiene
Cu-Cls 196to 270
C,6-C20 287to 343
>Cm >355
X
X
X
X X
X X
X X X X
X
X X
D3239, Aromatic types in gas oil aromatic fractions by MS D3701, Hydrogen content of fuels by NMR D4053, Benzene content of gasoline by IR D4808, Hydrogen content of petroleum products by NMR D5292, Aromatic carbon and hydrogen by NMR D5845, Oxygenates in gasoline by IR Chemical Methods D483, Unsulfonated residue of spray oils I)664, Neutralization number by potentiometric titration D847, Acidity in solvent naphthas and aromatics D974, Neutralization number by color-indicator method D 1159, Bromine number by electrome~c titration
C6-Cio 69to 174
X X
X
X
X X
X
X X X
X X
X
X
X
X X X
X X X X
X X
X X
X X
X X
X X
X X
X X
X X X X
X
X X
Miscellaneous Methods
D 130, Copper strip corrosion D156, Saybolt color D ! 87. Burning quality of kerosine D381, Existent gum in fuels D525, Oxidation stability of gasoline (induction period)
X X X X X
D613, Cetane quality of diesel fuels D848, Acid wash color of aromatics D849, Copper corrosion of aromatics D873, Oxidation stability of aviation fuels D909, Knock characteristics of aviation fuels
X X
D 1133, Kauri-Butanol value D1265, Sampling LP gas D2121, Polymer in styrene D2274, Oxidation stability of distillate fuels D2276, Particulate contamination in aviation turbine fuels
X
X X X
X
X X X X
X X
INTRODUCTORY INFORMATION
T a b l e 2 - continued Number of Carbon Atoms Boiling Range of Normal P~affms at 760 mm Hg, °C
CcC~ -161 to -89
D2624, Electrical conductivity of aviation and distillate fuels D2699, Knock characteristics by research octane D2700, Knock characteristics by motor octane D2713, Dryness of propane (valve freeze) D2780, Solubility of fixed gases in liquids
D2878, D2885, D3235, D3241, D3700,
Estimating vapor pressure of lubricating oils Knock characteristics by on-line analyzers Solvent extractables in waxes Thermal oxid. stab. of aviation turbine fuel (JFTOT) Sampling using floating piston cylinder
D5274, Guide for analysis of butadiene D5287, Automatic sampling of gaseous fuels D5386, Color of liquids D5503, Natural gas sample-handling D5842, Sampling of fuels for volatility
D2622, Sulfur by X-ray D2709, Water and sediment in fuels D2784, Sulfur in LP gases D3120, Trace sulfur by oxidative microcoulometry D3227, Mercaptans in distillates (potentiometric)
Cn-Cts 196 to 270
C~6-C~o 287 to 343
X
X
>(22o >355
X X
X X
X
X X
X
X X X
X
X
X X
X X X
X X X X X
X X X X
X X
X X X
X
X X
X X X
X X X X
X X X X
X X
X
X
X X
X X
X X X
X X X
X X
Non-Hydrocarbon Methods D95, Water by distillation D96, Water and sediment in crude oils D129, Sulfur by bomb method D808, Chlorine in petroleum products D853, H2S and SO2in aromatics D!266, Sulfur by lamp method D1552, Sulfur by high-temperature method D1685, Thiophene in benzene D1988, Mercaptans in natural gas D2420, Hydrogen sulfide in LP gases
Ce,-CIo 69to 174
X X
D3948, Water separation charact, of aviation turbine fuel D4057, Manual sampling of petroleum D4 i 77, Automatic sampling of petroleum D4291, Ethylene glycol in used engine oil D4307, Preparation of liquid blends D4419, Transition temperatures of wax by DSC D4740, Stability of residual oils by spot test D5184, AI and Si in fuel oils by ICP-AES and AAS D5234, Guide for analysis of ethylene D5273, Guide for analysis of propylene
C3-Cs -42 to +36
X
X
X X
X X
X
X X
X X
X
X
X X
X X
X
9
10
MANUAL ON HYDROCARBON A N A L Y S I S Table 2 - continued
Number of Carbon Atoms Boiling Range of Normal Paraffins at 760 mm Hg, °C D3230. D3231, D3237, D3246, D3341,
Salt in crude oil Phosphorus in gasoline Lead in gasoline by AAS Sulfur in gases by oxidative microcoulometry Lead in gasoline (iodine monochloride)
CfC~ -161 to -S9
X
X
134951, D5185, D5194, D5291, D5384,
Additive elements in lube oils by ICP-AES Additive elements in lube oils by ICP-AES Trace chloride in aromatics C, H and N in petroleum products Chlorine in used oils
D5453, D5454, D5622, D5708, D5762,
Sulfur in fuels and oils Water vapor in gaseous fuels Total oxygen by reductive pyrolysis Ni, V and Fe in crude oil by ICP-AES Nflrogen by chemiluminescence
D5808, D5863, D6069, D6212,
Organic chloride in aromatics by microenulometry Ni, V, Fe and Na in crude oil by AAS Trace nitrogen in aromatics by chemiluminescence Total sulfur in aromatics by rateometric colorimetry
X X X
Cn'C~5 196 to 270
C~6-C2o 287 to 343
>C~ >355
X
X
X
X
X X
IM047, Phosphorus in lubricating oils D4294, Total sulfur by XRF D4377, Water in crude oil by Karl Fischer D4628, Ba, Ca, Mg, and Zn in oils by AAS D4629, Trace nitrogen by chemiluminescence D4888, Water in natural gas D4927, Ba, Ca, P, S and Zn by XRF D4928, Water in crude oils IM929, Chloride in crude oils
c.-c,o 69to 174
X
D3605, Trace metals in fuels by AAS D3961, Sulfur in aromatics by oxidative microcoulometry D4006, Water in crude oil by distillation D4007, Water and sediment in crude oil by centrifuge D4045, Sulfur by hydrogenolysis and rateometric colorimetry
1)4810, H2Sin natural gas
C.-Cs -42 to +36
X
X X
X
X
X X X X
X X X
X X X
X X
X X
X X
X
X
X X X X X
X X X X X
X X
X X
X X X
X X X
X X
X X
X X
X
X X
X
X
X X X
X X
X X
X
X
X
X
X X X X
X
X
X X
X
X X X X
INTRODUCTORY
INFORMATION
aa~aa~aa~aa~
a
aa~a~aaa~aa
n
aa~a~aa~aaa
a
~, a a a a ~ a a a a a a
11
11.
i
aaaaa~aaaaaa
a
a a a ~ a ~ a a a
a
aaaaa~aaaaa a a a ~ a ~ ~ a a aaaa~aa ~
E
r-
_
aa
aaaa
~aa
a
aaaa
~aa
aaa~
~a~
a
aa~
~a
a
~aa
~a
~aa
~a
o
*6 o .r. Z
E E v"
m
t"q
o
l
E o i0
~al
~II
all
~II
Q
c
._o
$
!'
all
~II
all
III
I
12
MANUAL ON HYDROCARBON A N A L Y S I S
A manual on hydrocarbon analysis would not be complete without considerable attention to non-hydrocarbons that occur in all crude oils and products. These impurities can range in concentration from parts-per-billion to percent levels, depending on the type of crude oil or specific fraction. Accurate determination of elements such as sulfur, nitrogen, or oxygen as well as numerous metals can be of the utmost importance. The analyst is constantly being challenged to determine these materials at lower and lower levels. Even minute concentrations of these elements can be fatal to sensitive catalytic systems that are now being used in most refining processes. With the introduction of oxygenated motor fuels, the determination of oxygen-containing compounds has become mandatory while complicating the determination of hydrocarbons in their presence. Finally, a word on correlative methods. Numerous calculation methods have been developed to relate chemical or physical properties to composition or processability. Other correlative methods allow direct comparison of data that have been obtained by totally different procedures. A particularly good example of this is the correlation of boiling range by gas
chromatography (ASTM Test Methods D2887 on Boiling Range Distribution of Petroleum Fractions by Gas Chromatography and D3710 on Boiling Range Distribution of Gasoline and Gasoline Fractions by Gas Chromatography) as compared to physical distillation (ASTM Test Methods D86 on Distillation of Petroleum Products at Atmospheric Pressure and D 1160 on Distillation of Petroleum Products at Reduced Pressures). ASTM Subcommittee D02.04 on Hydrocarbon Analysis is actively engaged in finalizing this particular correlation. Other correlation methods are available, some of which are listed in Table 2. As analytical technology and the petroleum industry change, older methods will be revised or discontinued and new ones developed. Within this dynamic system, new challenges will continue to face the analyst as quickly as older problems are solved. Through the efforts of ASTM members, new concepts will be evaluated, proven, and formalized as consensus test methods. A. W. Drews Subcommittee D02.04 on Hydrocarbon Analysis
Part l--Discussion of Analyses
by Product Type
Analysis of Cs and Lighter Hydrocarbons
1
by Neil G. Johansen
INTRODUCTION
ble among these are ASTM Standard Practices D5287, Automatic Sampling of Gaseous Fuels,1 D5503, Natural Gas Sample-Handling and Conditioning Systems for Pipeline Instrumentation, I D1265, Sampling Liquefied Petroleum (LP) Gases (Manual Method), l and D3700, Containing Hydrocarbon Fluid Samples Using a Floating Piston Cylinder? Sampling of low-pressure materials is described in ASTM Standard Practices D4057, Manual Sampling of Petroleum and Petroleum Products/ D4177, Automatic Sampling of Petroleum and Petroleum Products, ~ and D5842, Sampling and Handling of Fuels for Volatility Measurement. 1 The preparation of gaseous and liquid blends is described in ASTM Standard Practices D4051, Preparation of LowPressure Gas Blends, 2 and D4307, Preparation of Liquid Blends for Use as Analytical Standards. 1 While sampling of C1 and C2 hydrocarbons is typically performed using stainless steel cylinders, either lined or unlined, other containers are employed dependent upon particular situations; for example, glass cylinder containers or PVF sampling bags. The preferred method for sampling C a and C4 hydrocarbons is by the use of piston cylinders, ASTM Standard Practice D3700, although sampling these materials as gases is also acceptable in many cases. The sampling of C5 and higher hydrocarbons is dependent upon the vapor pressure of the sample. Piston cylinders or pressurized steel cylinders are advisable for high-vapor pressure samples (containing significant amounts of light gases), while atmospheric sampling may be used for low-vapor pressure samples.
THE LIGHTHYDROCARBONS--methane (C~), ethane (C2), propane (Ca), and the butanes (C4), either in the gas phase or liquefied, are primarily used for heating, motor fuels, and as feedstocks for chemical processing. The pentanes/pentenes (C5) are products of natural gas or petroleum fractionation or refinery operations (i.e., reforming and cracking) that are removed for use as chemical feedstocks. The olefins--ethene (ethylene), propene (propylene), butenes (butene-1, isobutylene, cis- and trans-butene-2, and the butadienes), pentenes, and pentadienes are materials produced by various refining processes involving the use of the saturated hydrocarbons as feedstocks. Mixtures of these hydrocarbons are commonly encountered in material testing, and the composition varies depending upon the source and intended use of the material. Other non-hydrocarbon constituents of these mixtures are important analytes since they may be useful products or may be undesirable as a source of processing problems. Some of these components are helium, hydrogen, argon, oxygen, nitrogen, carbon monoxide, carbon dioxide, sulfur, and nitrogen containing compounds, as well as heavier hydrocarbons. Desired testing of these hydrocarbon mixtures usually involves the determination of bulk physical or chemical properties and component speciation and quantitation. ASTM addresses the characterization and specification of the C~ to C5 hydrocarbon materials and products through several venues. Committee D03 is responsible for gaseous fuels; Committee D02, Subcommittee H is responsible for liquefied petroleum gas; Committee D02, Subcommittee D is responsible for hydrocarbons for chemical and special uses, while Committee D02, Subcommittee 4 has responsibility for test methods involving hydrocarbons in general. Committees D19 (Water) and D22 (Sampling and Analysis of Atmospheres) address environmental concerns involving light hydrocarbons.
Analysis ASTM test methods for gaseous fuels and petroleum products have been developed over many years, extending back into the 1930s. Bulk physical property tests, such as density and heating value, as well as some compositional tests, such as the Orsat analysis and the mercuric nitrate method for the determination of unsaturation, were widely used. Mass spectrometry became the method of choice for compositional analysis of light hydrocarbons, and ASTM Test Method D2650, Chemical Composition of Gases by Mass Spectrometry/ was standardized in 1967 to replace several older methods. Currently the mass spectrometry method has been replaced, in practice, by gas chromatography as the technique of choice for fixed gas and hydrocarbon speciation.
CURRENT PRACTICES
Sampling One of the more critical aspects for the analysis of light hydrocarbons is the question of sampling. Sampling of gaseous and liquefied materials is addressed in a variety of specific sampling methods, and many of the test methods themselves contain additional sampling requirements. Nota-
1Appears in this publication. 2Annual Book of ASTM Standards, Vol. 05.02.
15
16
MANUAL ON HYDROCARBON ANALYSIS
Natural and Reformed Gas
Light Olefins (C2, C3, C. and C5)
ASTM Test Method D1945, Analysis of Natural Gas by Gas Chromatography, ~and ASTM Practice D 1946, Analysis of Reformed Gas by Gas Chromatography, 1 describe procedures for the determination of hydrogen, helium, oxygen, nitrogen, carbon monoxide, carbon dioxide, methane, ethene, ethane, propane, butanes, pentanes, and hexanes-plus in natural and reformed gases by packed column gas chromatography. These compositional analyses are used to calculate many other properties of gases, such as density, heating value, and compressibility. The first five components listed are determined using a molecular sieve 13X column (argon carrier gas), while the remaining components are determined using polydimethylsiloxane partition or porous polymer columns. The hexanes-plus analysis is accomplished by backflushing the column after the elution of pentane or by the use of a bacldlushed precolumn. Important constituents of natural gas not accounted for in these analyses are moisture (water) and hydrogen sulfide, as well as other sulfur compounds. Water content is determined by ASTM Test Methods D 1142, Water Vapor Content of Gaseous Fuels by Measurement of Dew-Point Temperature, ~ D5454, Water Vapor Content of Gaseous Fuels Using Electronic Moisture Analyzers, ~ or D4888, Water Vapor in Natural Gas Using Length-of-Stain Detector Tubes) ASTM Test Method D5504, Sulfur Compounds in Natural Gas and Gaseous Fuels by Gas Chromatography and Chemiluminescence, I best accomplishes sulfur compound determination, although ASTM Test Methods D 1988, Mercaptans in Natural Gas Using Length-of-Stain Detector Tubes, ~ and D4810, Hydrogen Sulfide in Natural Gas Using Length-ofStain Detector Tubes, ~ can also be used with some loss in accuracy.
Characteristics and corresponding test methods for these materials have been outlined in three ASTM standard guides: D5234, Analysis of Ethylene Product, ~ D5273, Analysis of Propylene Concentrates, 1 and D5274, Analysis of 1,3Butadiene Product. 1 A proposed Guide for the Analysis of Isoprene is being developed. These guides list properties to be measured and the range of values expected, as well as appropriate test methods where available. Hydrocarbon analysis of ethene is accomplished using ASTM Test Methods D2505, Ethylene, Other Hydrocarbons, and Carbon Dioxide in High-Purity Ethylene by Gas Chromatography, l and ASTM Test Method D6159, Hydrocarbon Impurities in Ethylene by Gas Chromatography.l D6159 is a new test method using wide-bore (0.53-mm) capillary columns, including a A1203/KCI PLOT column. Currently, ASTM Test Method D2504 is recommended for determination of noncondensable gases, and ASTM Test Method D2505 is used for the determination of carbon dioxide; however, a new method is under development in ASTM to address these analyses. ASTM Test Methods D2712, Hydrocarbon Traces in Propylene Concentrates by Gas Chromatography, 1 and D2163, also a gas chromatographic method, are currently recommended for the determination of hydrocarbon impurities in propene. ASTM Test Method D4864, Determination of Traces of Methanol in Propylene Concentrates by Gas Chromatography, l is used for methanol determination. ASTM Test Method D5303, Trace Carbonyl Sulfide in Propylene by Gas Chromatography, 1 is used for carbonyl sulfide determination with a flame photometric detector. ASTM Test Method D3246, Sulfur in Petroleum Gas by Oxidative Microcoulometry, 1 is currently recommended for the determination of total sulfur, and the method is being revised to be more generally applicable to light hydrocarbon analysis. Commercial butylenes, high-purity butylenes, and butanebutylene mixtures are analyzed for hydrocarbon constituents by ASTM Test Method D4424, Butylene Analysis by Gas Chromatography) Hydrocarbon impurities in 1,3-butadiene are determined by ASTM Test Method D2593, Butadiene Purity and Hydrocarbon Impurities by Gas Chromatography) Butadiene dimer and styrene are determined in butadiene using ASTM Test Method D2426, Butadiene Dimer and Styrene in Butadiene Concentrates by Gas Chromatography) Carbonyls in C4 hydrocarbons are determined by a titrimetric technique using ASTM Test Method D4423, Determination of Carbonyls in C4 Hydrocarbons. ~ ASTM Test Method D5799, Determination of Peroxides in Butadiene, t is used for peroxide determination.
Liquefied Petroleum (LP) Gases Propane, iso-butane, and butane generally constitute this sample type and are used for heating, motor fuels, and as chemical feedstocks. ASTM Test Methods D2597, Analysis of Demethanized Hydrocarbon Liquid Mixtures Containing Nitrogen and Carbon Dioxide by Gas Chromatography,l D2163, Analysis of Liquefied Petroleum (LP) Gases and Propene Concentrates by Gas Chromatography, l and D2504, Noncondensable Gases in C2 and Lighter Hydrocarbon Products by Gas Chromatography, ~ are methods for determining light hydrocarbons and some fixed gases in LP gases. Total sulfur is determined by ASTM Test Method D2784, Sulfur in Liquefied Petroleum Gases (Oxy-Hydrogen Burner or Lamp). ) Sulfur compound determination is made using ASTM Test Method D5623, Sulfur Compounds in Light Petroleum Liquids by Gas Chromatography and Sulfur Selective Detection. ~Trace total organic and bound nitrogen is determined using ASTM Test Method D4629, Trace Nitrogen in Liquid Petroleum Hydrocarbons by Syringe/Inlet Oxidative Combustion and Chemiluminescence Detection.~ The current test method for heavy residues in LP gases is ASTM Test Method D2158, Residues in Liquefied Petroleum (LP) Gases, t which involves evaporation of an LP Gas sample, measuring the volume of residue and observing the residue for oil stain on a piece of filter paper.
FUTURE TRENDS In general, gas chromatography will undoubtedly continue to be the method of choice for characterization of light hydrocarbon materials. New developments in higher-speed techniques for gas chromatographic instrumentation and data processing will lead to new and revised test methods. New and improved detection devices and techniques, such as chemiluminescence, atomic emission, and mass spectroscopy, will enhance selectivity, detection limits, and analytical productivity. Laboratory automation through autosampling,
CHAPTER 1--ANALYSIS OF Cs AND LIGHTER HYDROCARBONS computer control, and data handling will provide improved precision and productivity, as well as simplified method operation. Development of test methods for process (on-line) analysis and validation of these analyses are continuing under the direction of ASTM Committee D02.0D, Section l and D02.25. A proposed gas chromatographic/selective detection method is under development for the trace analysis of sulfur compounds in ethene and propene. ASTM Test Method D2163 is quite old. It utilizes lower resolution packed columns, a less sensitive detector, and manual peak area measurement. Thus, it is technically out of date, and Committee D02.0D is currently in the process of developing a revision for the determination of hydrocarbons in LP gases and lower-purity mixtures of C3 and C4 hydrocarbons. The revision will still be performance based, but the recommended column will be the A1203/KC1 PLOT column, as used in the recently standardized ASTM Test Method D6159,
17
as well as in another test method under development for high-purity propene. A continuing problem for LP gas characterization is the accurate determination of heavy residues (i.e., oils) in LP gas. New test methods have been proposed using procedures similar to those employed in gas chromatographic simulated distillation, and this development work is continuing. The development of test methods for C5 hydrocarbons (olefins) has begun recently and should result in ASTM standards in the near future. Various petroleum refinery process streams, often containing olefinic compounds, are generically referred to as "refinery gas." Although no ASTM test method is available for this determination, several instrumentation and technology suppliers market automated gas chromatographic systems as "refinery gas analyzers." ASTM standardization of this technology would be beneficial to users of these analyzers.
Analysis of Gasoline and Other Light Distillate Fuels by James M. McCann
INTRODUCTION
During the early 1950s, instrumental analytical techniques, such as mass spectrometry, infrared, and ultraviolet spectroscopy, were being explored and used for hydrocarbon composition and structural analysis. Beginning with the mid 1950s, publications on gas chromatography began to appear in the literature, and this new technique was soon being used for analyzing a wide variety of hydrocarbon streams. As commercial instrumentation was developed, the application of gas chromatography grew rapidly, with volumes of information being published from its beginning up to the present time. Recently, more rapid spectrometry methods such as infrared and near-infrared and the use of hyphenated analytical techniques, for example GC-MS, have been applied.
THE CHALLENGETO DEVELOPmore accurate and precise test methods for the analysis of gasoline or automotive sparkignition engine fuel has been tremendously influenced by federal and state regulations covering the production of reformulated gasolines (RFG) with tight limits on many parameters [1]. 1 Examples of these new fuels include U.S. Environmental Protection Agency (EPA) RFG and California Air Resources Board (CARB) Phase 2 Gasoline. The regulated RFG test parameters include vapor pressure, distillation, benzene content, total aromatics, total olefins, individual oxygenates, oxygen content, and total sulfur. Regulatory requirements have enhanced the need for better test methods to control manufacturing and the distribution of gasolines. The addition of alcohol and ether as important blending components to gasoline to meet air quality standards has necessitated modifying some existing test methods and the development of new procedures. The desire to reduce manufacturing costs, coupled with the regulatory requirements, have enhanced the application of more cost effective test methods including rapid screening procedures and wider use of online analyzers. In this chapter, a brief history of ASTM method development for hydrocarbon analysis of gasoline is given. The focus, however, will be on some of the test parameters required for today's reformulated gasolines including many of the new test methodologies. ASTM standardization of methods for hydrocarbon analysis started in 1942 when Committee D02, Technical Division on Gasoline, established a subgroup to standardize a procedure for the determination of aromatics in gasolines for use by the military. This method was first issued in March of 1943 as Emergency Standard ES 45, Test for Olefins, Aromatics, Paraffins, and Naphthenes in Aviation Gasoline (Without Distillation Into Fractions). 2 This method was a combination of several procedures, some of which are still commonly used. In 1948, a procedure was described by A. L. Conrad and later refined by D. W. Cridle and R. L. LeTourneau for determining olefins, aromatics, and saturates in cracked gasoline. This procedure evolved into ASTM Test Method D1319, Hydrocarbon Types in Liquid Petroleum Products by Fluorescent Indicator Adsorption, 3 often abbreviated as "FIA."
CURRENT PRACTICES Analysis of Gasoline Range Hydrocarbons The following is a review of applicable test methods that can be used to measure some of the key parameters in gasoline range hydrocarbons.
Distillation The primary method specified for determining boiling range of gasoline continues to be ASTM Test Method D86, Distillation of Petroleum Products at Atmospheric Pressure. 3 The use of automated instrumentation has been incorporated into the method. ASTM Test Method D3710, Boiling Range Distribution of Gasoline and Gasoline Fractions by Gas Chromatography, 3 (GC), can be used for determining the boiling point properties of oxygenate-free gasoline distillates. ASTM D3710 has the advantage that it uses a smaller sample size and can be more easily automated, but D3710 data are not directly equivalent to that obtained by D86 distillation. ASTM D3710 data are being used by some companies and vendors by applying correlations to predict D86 distillation data for various refinery streams. Improvements in the GC simulated distillation procedures have been implemented in some laboratories and are being evaluated in ASTM D02.04, Section H. Improvements include rapid gas chromatography techniques using very narrow bore capillary gas chromatography columns that will potentially reduce analysis time to a few minutes [2].
~The italic numbers in brackets refer to the references at the end of this chapter. 21944 Annual Book of ASTM Standards, Part III. 3Appears in this publication.
Vapor Pressure The vapor pressure of gasoline is a critical physical test parameter for today's gasoline. ASTM Test Method D323,
18
CHAPTER 2--ANALYSIS OF GASOLINE AND OTHER DISTILLATE FUELS Vapor Pressure of Petroleum Products (Reid Method), 3 had been widely used in the past. ASTM Test Method D5191, Vapor Pressure of Petroleum Products (Mini Method), 3 is now most commonly referenced in gasoline regulations. This method requires less sample and is much easier and faster to run. Other ASTM Test Methods for vapor pressure of gasoline include D4953, Vapor Pressure of Gasoline and Gasoline-Oxygenate Blends (Dry Method), a D5190, Vapor Pressure of Petroleum Products (Automatic Method), 3 and D5482, Vapor Pressure of Petroleum Products (Mini MethodAtmospheric). 3
Oxygenates ASTM test methods have been developed to measure ethers and alcohols in gasoline range hydrocarbons, because oxygenated components such as methyl-tert-butylether and ethanol are common blending components in current gasolines. ASTM Test Methods D4815, MTBE, ETBE, TAME, DIPE, tertiary-Amyl Alcohol and C1 to C4 Alcohols in Gasoline by Gas Chromatography, a and D5599, Oxygenates in Gasoline by Gas Chromatography and Oxygen Selective Flame Ionization Detection, 3 were adopted for measuring oxygenates and oxygen content. ASTM D4815 is a widely used method and is currently the designated test method in California. ASTM D5599 is a GC capillary column method employing an oxygen selective flame ionization detector and was based upon the EPA designated test for oxygenates in gasoline [3 ]. It can detect any oxygenated component that elutes from the gas chromatographic (GC) column. ASTM D5986, Oxygenates, Benzene, Toluene, C8-C12 Aromatics and Total Aromatics in Finished Gasoline by Gas Chromatography/Fourier Transform Infrared Spectroscopy (GC/FTIR), 3 is more complex, but it can determine oxygenates, benzene, and total aromatics in a single analysis. ASTM Test Method D5622, Total Oxygen in Gasoline and Methanol Fuels by Reductive Pyrolysis, 3 can be used to directly determine mass percent total oxygen in fuels. ASTM Test Method D5845, MTBE, ETBE, TAME, DIPE, Methanol, Ethanol and tert-Butanol in Gasoline by Infrared Spectroscopy,3 is particularly useful as a rapid portable screening tool for oxygenates in gasoline. In addition, gas chromatography with an atomic emission detector has been used by laboratories to measure specific oxygenated components in gasoline [4,5 ].
Benzene and Aromatics The accurate measurements of benzene and total aromatics in gasoline are regulated test parameters in modern gasoline. ASTM Test Method D3606, Benzene and Toluene in Finished Motor and Aviation Gasoline by Gas Chromatography, 3 (GC), is a procedure accepted by the EPA as the designated test for benzene in gasoline. The precision and accuracy of D3606 is diminished in gasolines containing ethanol or methanol, since these components do not completely separate from the benzene peak. A modified version of D3606 is practiced using a different internal standard and a different set of gas chromatographic columns that gives better separation of ethanol or methanol containing fuels. This modified version of the test has not been cooperatively tested by ASTM. ASTM Test Method D5580, Benzene, Toluene, Ethylbenzene, p/m-Xylene, o-Xylene, C9 and Heavier Aromatics and Total Aromatics in Finished Gasoline by Gas Chromatography, 3
19
was developed to include fuels containing commonly encountered alcohols and ethers. D5580 has been accepted as the designated test for determining benzene and total aromatics in California Phase 2 gasolines. Hyphenated analytical instrumental methods including ASTM Test Method D5769, Benzene, Toluene and Total Aromatics in Finished Gasolines by Gas Chromatography/Mass Spectrometry3 (GC/MS), and ASTM D5986, (GC/FTIR), also accurately measure benzene in gasoline. ASTM D5769 is based upon the EPA GC/MS procedure for aromatics [6 ]. The results of ASTM D02 Subcommittee 4 round robin studies have shown that there is no significant bias among methods D5769, D5580, and D5986 for benzene in gasoline. Benzene can also be measured by ASTM Test Method D4053, Benzene in Motor and Aviation Gasoline by Infrared Spectroscopy? Other improved infrared procedures are being considered for standardization in ASTM. ASTM D 1319 (FIA) has traditionally been used to measure aromatics as well as olefins and saturates in gasoline. ASTM Test Method D5443, Paraffin, Naphthene, and Aromatic Hydrocarbon Type Analysis in Petroleum Distillates through 200°C by Multi-Dimensional Gas Chromatography, 3 can be used to measure hydrocarbon types by carbon number. Olefins, if present, are converted to saturates and are included in the paraffin and naphthene distribution. The scope of ASTM D5443 excludes hydrocarbons containing oxygenates. An extended version of the technique, which has not been standardized, measures paraffins, isoparaffins, olefins, naphthenes, and aromatics (PIONA) in gasoline range hydrocarbons [6 ]. ASTM Test Methods D5580 (GC), D5769 (GC/ MS), and D5986 (GC/FTIR) were adopted as a new test methods for aromatics in gasoline including fuels containing oxygenates. ASTM D5769 is based upon an EPA procedure for aromatics in gasoline [7 ]. The results of these total aromatics tests are not necessarily equivalent.
Total Olefins ASTM Test Method D 1319 (FIA) is widely used for measuring total olefins in gasoline fractions as well as aromatics and saturates. D 1319 results must be corrected for the presence of oxygenates, and the precision of the method is poor. A titration procedure, ASTM Test Method D 1159, Bromine Number of Petroleum Distillates and Commercial Aliphatic Olefins by Electrometric Titration, 3 provides an approximation of olefin content within a sample, while ASTM Test Method D2710, Bromine Index of Petroleum Hydrocarbons by Electrometric Titration, 3 can be valuable for determining trace olefin levels. These methods do not directly measure total olefins, and the results are affected by the type of olefinic compound present. Cooperative studies are underway in ASTM D02.04 to find a better test method for total olefins. Cooperative work has been done to validate new gas chromatographic methods that trap the olefins on silver nitrate impregnated traps. These include a gas chromatographic multi-dimensional procedure for oxygenates and paraffin, olefin, naphthene, aromatic (O-PONA) hydrocarbon types in petroleum distillates and a GC fast total olefins analyzer (FTO) method. The FTO method has the advantage that the analysis time is quicker. The O-PONA method is an expanded version of ASTM D5443 and
20
MANUAL ON HYDROCARBON ANALYSIS
gives a detailed breakdown of the oxygenates and hydrocarbon types by carbon number. The use of supercritical fluid chromatography, (SFC), applied to gasoline analysis with a flame ionization detector, was first reported in 1984 by T. A. Norris [8 ]. Studies in Section C of ASTM D02.04 found the chromatographic column difficult to reproduce. Recent work has begun on a new multi-dimensional column approach for determining total olefins in gasoline by SFC. SFC combined with gas chromatography and or mass spectrometry has been reported giving a more detailed hydrocarbon type characterization [9,10 ]. Mass spectrometry techniques have also recently been reported for the determination of olefins in hydrocarbons or gasoline. These include the use of hydrogenation techniques and acetone chemical ionization mass spectrometry [11,12 ].
Detailed Hydrocarbon Analysis ASTM Test Method D5134, Detailed Analysis of Petroleum Naphthas through n-Nonane by Capillary Gas Chromatography, a is applicable to olefin-free liquid hydrocarbon mixtures including virgin naphthas, reformates, and alkylates. Higher resolution gas chromatography capillary column techniques are in routine use in petroleum laboratories today to provide a detailed analysis of most of the individual hydrocarbons in gasoline, including many of the oxygenated blending components. Software is also available that allows one to summarize the data according to hydrocarbon type and predict other parameters such as vapor pressure and distillation from the results. High-resolution GC procedures for the detailed analysis of gasoline are being considered for adoption as standard ASTM test methods. Capillary GC techniques can be combined with mass spectrometry [13 ] to enhance the identification of the individual components and hydrocarbon types.
Sulfur Content Sulfur-containing components exist in gasoline range hydrocarbons. Individual sulfur components can be speciated using ASTM Test Method D5623, Sulfur Compounds in Light Petroleum Liquids by Gas Chromatography and Sulfur Selective Detection) This method uses a gas chromatographic capillary column coupled with either a sulfur chemiluminescence detector or atomic emission detector (AED). The total sulfur content is an important test parameter in gasoline. The most widely specified method for total sulfur content is ASTM Test Method D2622, Sulfur in Petroleum Products by X-Ray Spectrometry. 3 ASTM Test Methods D5453, Total Sulfur in Light Hydrocarbons, Motor Fuels and Oils by Ultraviolet Fluorescence, 3 and D4045, Sulfur in Petroleum Products by Hydrogenolysis and Rateometric Colorimetry, 3 are also applicable, particularly at lower sulfur levels. Studies have also been conducted in ASTM D02.03 on Elemental Analysis to improve these tests and evaluate newer methods.
Octane N u m b e r ASTM Test Methods D2700, Motor Octane Number of Spark-Ignition Engine Fuel, 4 D2699, Research Octane Number of Spark-Ignition Engine Fuel, 4 and D2885, Research and Motor Method Octane Ratings Using On-Line Analyzers, 4 are
4Annual Book of ASTM Standards, Vol. 05.04.
standardized tests used to determine the ignition quality of gasoline. Aviation gasolines are tested by ASTM Test Method D909, Knock Characteristics of Aviation Gasolines by the Supercharge Method. 4 Calculation of octane numbers based on compositional analysis obtained by gas chromatography has also been practiced by some companies. Octane can be predicted by using principle component regression of chromatographic data [14 ]. Today, spectroscopy techniques such as near-infrared (NIR), infrared (IR) spectroscopy, and nuclear magnetic resonance (NMR) are applied by many companies and instrument vendors for the prediction of octane numbers and other parameters of gasoline [15-18 ].
Analysis of Hydrocarbon Solvents Although "hydrocarbon solvents" are not considered "fuels," it is appropriate to mention them because they are hydrocarbon distillates. Solvent tests are generally performed to ensure the quality of a given product as supplied by the producer to the consumer. Many solvent tests are of a somewhat empirical nature such as aniline point, ASTM Test Method D611, Aniline Point and Mixed Aniline Point of Petroleum Products and Hydrocarbon Solvents, 3 and kauributanol number, ASTM Test Method D1133, Kauri-Butanol Value of Hydrocarbon Solvents. 3 These are cited in specifications and serve a useful function as control tests. Solvent purity, however, is monitored mainly by gas chromatography, with individual non-standardized tests routinely being used by the associated industry. One method that resulted from health concerns and the need to reduce the benzene contents of solvents is ASTM Test Method D4367, Benzene in Hydrocarbon Solvents by Gas Chromatography. 3
FUTURE TRENDS It is anticipated that regulations and specifications for gasoline will continue to evolve. To meet these future regulations and the changing requirements of the automotive industry, the composition of gasoline will also be changed and improved. New analytical methods will be developed to accurately test these new fuels. Petroleum-testing laboratories will apply more rapid spectroscopy techniques, faster chromatography methods, and hyphenated analytical techniques capable of measuring multiple parameters in a single analysis. More precise test methods will be implemented employing smaller sample sizes, less toxic reagents, and fewer calibration materials. The acceptance of alternative test methodologies will expand as government agencies recognize performance-based test methods for fuel analysis. In particular, the utilization and acceptance of more cost effective on-line test methods, including techniques such as NIR, FTIR, NMR, and Fiber-Optic FT Raman Spectrometry, will continue to expand [19,20 ].
REFERENCES [1 ] McCann, J. M., "ASTM Faces New Testing Challenges Created by Reformulated Gasoline Regulations," ASTM Standardization News, June 1994, pp. 23-25.
C H A P T E R 2 - - A N A L Y S I S OF G A S O L I N E A N D O T H E R D I S T I L L A T E F U E L S [2 ] Giarrocco, V., "Two-Minute Simulated Distillation Analysis of Gasoline Range Materials Using Short 100-/zm Diameter Caprilary Columns," Hewlett-Packard Company Application Note 228-370, Publication Number 23-5965-6416E, January 1997, Hewlett-Packard Company, Wilmington, DE. [3 ] EPA GC/OFID Method, EPA, Dec. 15, 1993, Final Rulemaking on Reformulated Gasoline. [4 ] Quimby, Giarrocco, V. and Sullivan, J., "Fast Analysis of Oxygen and Sulfur Compounds in Gasoline by GC-AED,"Journal of High Resolution Chromatography, Vol. 15, November 1992, pp. 705-709. [5 ] Diehl, J., Finkbeiner, J., and DiSanzo, F., "Determination of Ethers and Alcohols in Reformulated Gasolines by GC/AED," Journal of High Resolution Chromatography, Vol. 18, No. 2, February 1995, pp. 108-110. [6 ] DiSanzo, F. P. and Giarrocco, V. J., "Analysis of Pressurized Gasoline-Range Liquid Hydrocarbon Samples by Capillary Column and PIONA Analyzer Gas Chromatography," Journal of Chromatographic Science, Vol. 26, 1988, pp. 258-401. [7 ] EPA GC/MS Method, EPA, Dec. 15, 1993, Final Rulemaking on Reformulated Gasoline. [8 ] Norris, T. A. and Rawdon, M. G., "Determination of Hydrocarbon Types in Petroleum Liquids by Supercritical Fluid Chromatography with Flame Ionization Detection," Analytical Chemistry, Vol. 56, 1984, pp. 1767-1769. [9] Chen, E.N. Jr., Drinkwater, D.E., and McCann, J.M., "Compositional Analysis of Hydrocarbon Groups in GasolineRange Materials by Multidimensional SFC-Capillary GC," Journal of Chromatographic Science, Vol. 33, 1995, pp. 353-359. [10 ] Drinkwater, D. E., Chen, E.N. Jr., and Nero, V. P., "Direct Analysis of Fuels by Supercritical Fluid Chromatography/Mass Spectrometry," Proceedings, 44th ASMS Conference on Mass Spectrometry and Allied Topics, 1997, Portland, Oregon. [11 ] Roussis, S. G. and Fedora, J. S., "Determination of Alkenes in Hydrocarbon Matrices by Acetone Chemical Ionization Mass
21
Spectrometry," Analytical Chemist~, Vol. 97, 1997, pp. 15501556.
[12 ] Cheng, M., Hudson, J., Drinkwater, D., and Nero, V., "Total Olefin in Gasoline Determined by Mass Spectrometry and Hydrogenation," Proceedings, 44th ASMS Conference on Mass Spectrometry and Allied Topics, 1997, Portland, Oregon. [13 ] Teng, S. T. and Williams, A. D., "Detailed Hydrocarbon Analysis of Gasoline by GC-MS (SI-PIONA)," Journal of High Resolution Chromatography, Vol. 19, 1994, pp. 469-475. [14 ] Crawford, N. F. and Hellmuth, W. W., "Refinery Octane Blend Modeling Using Principle Components Regression of Gas Chromatographic Data," Fuel, Vol. 69, 1990, pp. 443-447. [15 ] Welch, W. T., Bain, M. L., Russell, K., Maggard, S. M., and May, J. M., "Experience Leads to Accurate Design of NIR Gasoline Analysis Systems," Oil & Gas Journal, June 27, 1994, pp. 48-56. [16 ] Myers, M. E., Stollsteimer, J., and Wims, A. M., "Determination of Gasoline Octane Numbers from Chemical Composition," Analytical Chemistry, Vol. 47, No. 13, November 1975, pp. 23012304. [17 ] Ichikawa, M., Nonaka, N., Amono, H., Takada, I., Ishimori, H., Andoh, H., and Kumamoto, K., "Proton NMR Analysis of Octane Number for Motor Gasoline: Part IV," Applied Spectroscopy, Vol. 46, No. 8, 1992, p. 1294. [18 ] Andrade, J. M., Muniategui, S., and Prada, D., "Prediction of Clean Octane Numbers of Catalytic Reformed Naphthas Using FT-MIR and PLS," Fuel, Vol. 76, 1997, pp. 1035-1042. [19 ] Meusinger, R., "Gasoline Analysis by 1H Nuclear Magnetic Resonance Spectroscopy," Fuel, Vol. 75, 1996, pp. 1235-1243. [20 ] deBakker, C. J. and Fredericks, P. M., "Determination of Petroleum Properties by Fiber-Optic Fourier Transform Raman Spectrometry and Partial Least-Squares Analysis," Applied Spectroscopy, Vol. 49, No. 12, 1995, pp. 1766-1771.
Analysis of Kerosine, Diesel, and Aviation Turbine Fuel by GregoryHemighaus Chromatographic Methods
INTRODUCTION
The first level of compositional information is group-type totals. ASTM Test Method D1319, Hydrocarbon Types in Liquid Petroleum Products by Fluorescent Indicator Adsorption, ~ gives volume percent saturates, olefins, and aromatics in materials that boil below 315°C (600°F). This covers jet fuels but not all diesel fuels, most of which have an end point above 315°C. Despite this limitation, the method has been used widely for diesel fuel due to the lack of a suitable alternative. In 1988 the California Air Resources Board issued regulations that limited the aromatic content of diesel fuel sold in California starting in 1993. This heightened awareness that ASTM D1319 was not appropriate for diesel fuels led to efforts being initiated though ASTM to develop a suitable alternative. This led to the development of ASTM Test Method D5186, Determination of the Aromatic Content and Polynuclear Aromatic Content of Diesel Fuels and Aviation Turbine Fuels by Supercritical Fluid Chromatography. 1 This method does not separate saturates and olefins, so it cannot be used as a replacement for ASTM D1319. Another complication in comparing the two methods is that ASTM D1319 gives results in volume-percent while ASTM D5186 results are in mass-percent. Another approach to the determination of aromatics in middle distillates is high performance liquid chromatography, (HPLC), with refractive index (RI) detection [2 ]. The Institute of Petroleum has standardized this technique as IP-391. ASTM is currently considering this method and may adopt it as a standard. HPLC with dielectric constant detection [3 ] was considered by ASTM, but problems with detector stability prevented standardization.
KEROSINE, DIESEL, AND AVIATIONturbine fuel (jet fuel) are members of the class of petroleum products known as middle distillates. As the name implies, these products are heavier than gasoline but lighter than gas oils. Middle distillates cover the boiling range from approximately 175°C to 375°C (350°F to 700°F) and the carbon number range from about Cs to C24. Besides these products, gas turbine fuel, fuel oil (heating oil), and some marine fuels are also classified as middle distillates because they have a wide boiling range that overlaps the lighter fuels. These products have similar properties but different specifications as appropriate for their intended use. Methods for determining physical properties of these products are well established. They are listed in Table 2 and most will not be discussed further. Table 2 also lists methods for elemental analysis of middle distillates. This chapter will focus on compositional analysis of these products. Because of the number of isomers in this carbon number range (see Table 3), complete speciation of individual hydrocarbons is not possible for middle distillates. Compositional analysis of middle distillates is obtained in terms of hydrocarbon group type totals. These groups are most often defined by a chromatographic separation or a mass spectral Z-series.
CURRENT
PRACTICES
Distillation One of the most important physical parameters defining these products is their boiling range distribution. Historically, this has been measured by ASTM Test Method D86, Distillation of Petroleum Products at Atmospheric Pressure. ASTM D86 is a low-efficiency, one theoretical plate distillation. This has been adequate for product specification purposes; however, engineering studies require true boiling point (TBP) data. TBP data can be provided by ASTM Test Method D2892, Distillation of Crude Petroleum (15-Theoretical Plate Column)J However, this method is rather difficult, time consuming, and expensive to run. TBP data are most often obtained using ASTM Test Method D2887, Boiling Range Distribution of Petroleum Fractions by Gas Chromatography ~ (simulated distillation). Use of simulated distillation has been recently reviewed [1 ].2
Coupled Chromatographic Techniques The combination of HPLC with GC can provide more detailed compositional information than either technique alone. Typically HPLC is used to separate a particular hydrocarbon group (saturates, mono-aromatics, di-aromatics) and transfer it to a high-resolution GC column that can resolve many of the individual compounds [4,5 ]. Supercritical fluid chromatography, (SFC), can be used instead of HPLC to make the primary separation [6 ]. These are rather sophisti2The italic face numbers in brackets refer to references at the end of this chapter.
~Appears in this publication. 22
CHAPTER 3 - - A N A L Y S I S OF KEROSINE, DIESEL, AND AVIATION TURBINE FUEL cated techniques that are not yet suitable for routine analysis or standardization.
Spectrometric Methods Mass spectrometry has been a powerful technique for hydrocarbon-type analysis of middle distillates. It can provide more compositional detail than chromatographic analysis. Hydrocarbon types are classified in terms of a Z-series. Z in the empirical formula CnH2n+z is a measure of the hydrogen deficiency of the compound. ASTM Test Method D2425, Hydrocarbon Types in Middle Distillates by Mass Spectrometry/ determines eleven hydrocarbon types ranging from Z = + 2 (paraffins) to Z = - 18 (tticyclic aromatics). This method requires that the sample be separated into saturate and aromatic fractions before mass spectrometric analysis. This separation is standardized as ASTM Test Method D2549, Separation of Representative Aromatics and Nonaromatics Fractions of High-Boiling Oils by Elution Chromatography. I This separation is applicable to diesel fuel but not to jet fuel, since it is impossible to evaporate the solvent used in the separation without also losing the light ends of the jet fuel. Combined gas chromatography/mass spectrometry with Townsend discharge nitric oxide chemical ionization (TDNOCI GC/MS) has been used to give similar group-type results to ASTM D2425 but without pre-separation into saturates and aromatics [7 ]. In addition, this method can give the Z series information by carbon number showing how the composition changes with boiling point. Solid phase extraction followed by capillary GC/MS has been used for detailed analysis of aromatic hydrocarbons in diesel fuel [8 ]. The percentage of aromatic hydrogen atoms and aromatic carbon atoms can be determined by ASTM Test Method D5292, Aromatic Carbon Content of Hydrocarbon Oils by High Resolution Nuclear Magnetic Resonance Spectroscopy, ~ (NMR). Results from this test are not equivalent to mass- or volume-percent aromatics determined by the chromatographic methods. The chromatographic methods determine the mass- or volume-percentage of molecules that have one or more aromatic tings. Any alkyl substituents on the rings contribute to the percentage of aromatics determined by chromatographic techniques. ASTM D5292 gives the toolpercent of aromatic hydrogen or carbon atoms. NMR can also be used to determine mass-percent hydrogen in jet fuel by ASTM Test Method D3701, Hydrogen Content of Aviation Turbine Fuels by Low Resolution Nuclear Magnetic Resonance Spectrometry, 1 and in diesel fuels by ASTM Test Method D4808, Hydrogen Content of Light Distillates, Middle Distillates, Gas Oils, and Residua by Low Resolution Nuclear Magnetic Resonance Spectroscopy. ~ Naphthalene content is an important quality parameter of jet fuel. It can be determined by ASTM Test Method D1840, Naphthalene Hydrocarbons in Aviation Turbine Fuels by Ultraviolet Spectrophotometry. ~ This method uses an average absorptivity for C~0to C~3 naphthalenes so that two fuels with the same volume-percent naphthalenes but a different distribution of isomers could give different results.
23
Correlative Methods Correlative methods have long been used as a way of dealing with the complexity of petroleum fractions. Relatively easy to measure physical properties such as density, viscosity, and refractive index have been correlated to hydrocarbon composition. Several examples of this type of correlative methods are listed in Table 2. In recent years an entirely new class of correlative methods has been developed. These use near-infrared (NIR) or midinfrared spectra together with sophisticated chemometric techniques to predict a wide variety of properties. Properties such as saturates, aromatics, and freezing point of jet fuel [9 ] and density, viscosity, aromatics, heat of combustion, and cetane index of diesel fuel [10] have been successfully predicted. It is important to recognize that these methods are correlations and should not be used to estimate properties of fuels that are outside of the calibration set. There are currently no standard methods using these techniques that are applicable to middle distillates.
Non-Hydrocarbon Methods Although the focus of this book is hydrocarbon analysis, heteroatoms, mainly sulfur and nitrogen compounds, cannot be ignored. Methods for determining the concentration of these elements are well established and listed in Table 2. The combination of gas chromatography with element selective detection gives information about the distribution of the element. In addition, many individual heteroatomic compounds can be determined. Selective sulfur and nitrogen GC detectors, exemplified by the flame photometric detector (FPD) and the nitrogenphosphorus detector (NPD), have been available for many years. However, these detectors have limited selectivity for the element over carbon, exhibit non-uniform response, and have other problems that limit their usefulness. A new generation of element selective detectors has become available based on chemiluminescence and plasma emission spectroscopy that have excellent sensitivity, uniformity of response, and selectivity over carbon. Nitrogen compounds in middle distillates can be selectively detected by chemiluminescence [11 ]. Individual nitrogen compounds can be detected down to 100 ppb nitrogen. Gas chromatography with either sulfur chemiluminescence detection [12 ] or atomic emission detection [13 ] has been used for sulfur selective detection.
FUTURE TRENDS The trend toward more detailed compositional information is expected to continue. The combination of multiple chromatographic separations and spectroscopic detection is a very powerful approach to the analysis of complex petroleum fractions. The mass spectrometry group-type methods, including ASTM D2425, were developed on magnetic sector instruments that are no longer in use. ASTM is working on updat-
24
MANUAL ON HYDROCARBON ANALYSIS
ing these methods to be used on m o d e r n quadrupole mass spectrometers. The ability to rapidly predict m a n y fuel properties suggests that the infrared/chemometric correlative techniques m a y find their best applications in on-line process control rather t h a n in the laboratory.
REFERENCES [1 ] Abbott, D.J., "Chromatography in the Petroleum Industry," Journal of Chromatography Library Series, E. R. Adlard, Ed., Vol. 56, 1995, Elsevier, New York. [2 ] Sink, C. W. and Hardy, D. R., "Quantification of Compound Classes in Complex Mixtures and Fuels Using HPLC with Differential Refractive Index Detection," Analytical Chemistry, Vol. 66, 1994, pp. 1334-1338. [3 ] Hayes, P. C., Jr. and Anderson, S. D., "The Analysis of Hydrocarbon Distillates for Group Types Using HPLC with Dielectric Constant Detection: A Review," Journal of Chromatographic Science, Vol. 26, 1988, pp. 210-217. [4 ] Trisciani, A. and Munari, F., "Characterization of Fuel Samples by On-Line LC-GC with Automatic Group-Type Separation of Hydrocarbons," Journal of High Resolution Chromatography, Vol. 17, 1994, pp. 452-456. [5 ] Kelly, G. W. and Bartle, K. D., "The Use of Combined LC-GC for the Analysis of Fuel Products: A Review," Journal of High Resolution Chromatography, Vol. 17, 1994, pp. 390-397. [6 ] Lynch, T. P. and Heyward, M. P., "Coupled Packed SFC and Capillary GC for the Quantitative Analysis of Complex Petro-
leum Fractions," Journal of Chromatographic Science, Vol. 32, 1994, pp. 534-540. [7 ] Dzidic, I., Petersen, H. A., Wadsworth, P. A., and Hart, H. V., "Townsend Discharge Nitric Oxide Chemical Ionization Gas Chromatography/Mass Spectrometry for Hydrocarbon Analysis of the Middle Distillates," Analytical Chemistry, Vol. 64, 1992, pp. 2227-2232. [8 ] Bundt, J. et al., "Structure-Type Separation of Diesel Fuels by Solid Phase Extraction and Identification of the Two- and Three-Ring Aromatics by Capillary GC-Mass Spectrometry," Journal of High Resolution Chromatography, Vol. 14, 1991, pp. 91-98. [9 ] Lysaght, M. A., Kelly, J. J., and Callis, J. B., "Rapid Spectroscopic Determination of Percent Saturates and Freezing Point of JP-4 Aviation Fuel," Fuel, Vol. 72, 1993, pp. 623-631. [10 ] Fodor, G.E. and Kohl, K. B., "Analysis of Middle Distillate Fuels by Midband Infrared Spectroscopy," Energy and Fuels, Vol. 7, 1993, pp. 598-601. [11 ] Chawha, B., "Speciation of Nitrogen Compounds in Gasoline and Diesel Range Process Streams by Capillary Column Gas Chromatography with Chemiluminescence Detection," Journal of Chromatographic Science, Vol. 35, 1997, pp. 97-104. [12 ] Kabe, T., Ishihara, A., and Tajima, H., "Hydrodesulfurization of Sulfur-Containing Polyaromatic Compounds in Light Oil," Industrial Engineering Chemistry Research, Vol. 31, 1992, pp. 1577-1580. [13] Hutte, R. S., "Chromatography in the Petroleum Industry," Journal of Chromatography Library Series, E. R. Adlard, Ed., Vol. 56, 1995, Elsevier, New York.
Analysis of Viscous Oils by Thomas M. Warne
range; those methods that are used to measure chemical composition such as elemental and molecular structure analysis; and derivative methods that correlate measured properties with aspects of chemical composition.
INTRODUCTION VISCOUSOILSare those petroleum fractions and derived products that have higher boiling points than distillate fuels and are liquid at, or slightly above, room temperature. They contain 20 to 50+ carbon atoms and distill at temperatures above 260°C (500°F). Examples include refinery streams such as gas oils and residuum, heavier fractions obtained from refining processes such as catalytic cracking, reforming, polymerization, solvent extraction, and hydro- and thermal cracking. Viscous oils include finished products such as lubricants, process oils, and insulating oils. Asphalt and coke are discussed only incidentally. These hydrocarbons are important commercially, providing both finished products for sale and feedstocks for further processing, primarily to fuels. The hydrocarbon composition of the viscous oils and the presence of heteroatoms and metals as contaminants or additives are the major determinant of the quality of finished products prepared from them. Detailed analysis of viscous oils is far more complex than the analysis of hydrocarbon gases and lower molecularweight liquids. The number of types of molecules present increases rapidly as the number of carbon atoms per molecule increases. Hydrocarbons in the viscous oil range are generally extremely complex mixtures. Characterization does not focus on identifying specific molecular structures, but on classes of molecules (paraffins, naphthenes, aromatics, polycyclic compounds, polar compounds, etc.). Besides complexity, analysis of viscous oils may be complicated by handling problems. The higher viscosity of the fluids makes them more difficult to sample and transfer. Many viscous oils have a very dark color, which causes problems with some test methods. Finally, besides carbon and hydrogen, high molecular weight fractions of crude oil often contain oxygen, sulfur, and nitrogen compounds; trace quantities of metals may also be present. Determining the chemical form present for these elements provides additional important information. Finished products made using viscous oils may contain additives or contaminants that also require analysis.
Physical Tests Density (Gravity) Density or relative density (specific gravity) is used whenever conversions must be made between mass (weight) and volume measurements. This property is often used in combination with other test results to predict oil quality. Five ASTM procedures for measuring density or gravity are generally applicable to measurements on viscous oils. ASTM Test Method D287, API Gravity of Crude Petroleum and Petroleum Products (Hydrometer Method)/ and ASTM Practice D1298, Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method, t use an immersed hydrometer for measurement. ASTM D287 is a special case of the hydrometer method that provides results as API gravity. Two other ASTM Test Methods, D1480, Density and Relative Density (Specific Gravity) of Viscous Materials by Bingham Pyncnometer, 2 and D1481, Density and Relative Density of Viscous Materials by Lipkin Bicapillary Pycnometer, 2 use a pycnometer to measure density or specific gravity and have the advantage of requiring a smaller sample size. Finally, ASTM Test Method D4052, Density and Relative Density of Liquids by Digital Density Meter 1 (and the related ASTM Test Method D5002, Density and Relative Density of Crude Oils by Digital Density Analyzer)/ measure density with a digital density analyzer. This device, which has gained wide acceptance, determines density by analysis of the change in oscillating frequency of a sample tube when filled with test oil. Viscous oils generally do not create problems because of sample volatility; however, all of the test methods are sensitive to the presence of gas bubbles in the fluid. With viscous oils, particular care must be taken to exclude or remove gas bubbles before measurement. With dark-colored samples, it may be difficult to determine whether all air bubbles have been eliminated.
C U R R E N T PRACTICES Test methods of interest for hydrocarbon analysis of viscous oils include tests that measure physical properties such as density, refractive index, molecular weight, and boiling
~Appears in this publication. 2Annual Book of ASTM Standards, Vol. 05.01.
25
26
MANUAL ON HYDROCARBON ANALYSIS
Refractive Index Refractive index is the ratio of the velocity of light in air to the velocity of light in the measured substance. The numerical value of the refractive index varies inversely with the wavelength of light used and the temperature at which the measurements are taken. The refractive index of a substance is related to its chemical composition and may be used to draw conclusions about molecular structure. Two ASTM test methods are available for measuring the refractive index of viscous liquids. Both methods are limited to lighter-colored samples for best accuracy. Both methods were written for instruments which are no longer manufactured. ASTM Test Method D 1218, Refractive Index and Refractive Dispersion of Hydrocarbon Liquids/ is designed to use the Bausch & Lomb Precision Refractometer. This model is no longer manufactured. ASTM Test Method D 1747, Refractive Index of Viscous Materials,~ uses the Abbe type (Valentine) refractometer, which is no longer made. In both cases, other refractometers are available, but no cooperative work has been conducted to verify equivalence. There are also limitations on the availability of thermometers with suitable range and accuracy that will fit the instruments. ASTM Subcommittee D02.04.0D plans cooperative testing of modern commercial refractometers to develop precision data, but data are not yet available.
Molecular Weight Since viscous oils are commonly broad-boiling mixtures, measurements of molecular weight commonly provide massaverage or number-average measurements. A variety of methods are available. Molecular weight may be calculated from viscosity data using ASTM Test Method D2502, Estimation of Molecular Weight (Relative Molecular Mass) of Petroleum Oils from Viscosity Measurements. ~The current version requires centistoke viscosity at 100 and 210°F. The method is generally applicable to "average" petroleum fractions with molecular weight in the range 250 to 700. Samples with unusual composition, such as aromatic-free white mineral oils, or oils with very narrow boiling range, may give atypical results. For samples with higher molecular weight (up to 3000 or more) with unusual composition or for polymers, ASTM Test Method D2503, Relative Molecular Mass (Molecular Weight) of Hydrocarbons by Thermoelectric Measurement of Vapor Pressure, ~ is recommended. This method uses a vapor pressure osmometer to determine molecular weight. Low boiling samples may not be suitable if their vapor pressure interferes with the method. The method has only been standardized by ASTM for samples up to a molecular weight of 800. A third method is also available. ASTM Test Method D2878, Estimating Apparent Vapor Pressures and Molecular Weights of Lubricating Oils, ~ provides a procedure to calculate these properties from test data on evaporation. The procedure is based on ASTM Test Method D972, Evaporation Loss of Lubricating Greases and Oils.I The sample is partly evaporated at a temperature of 250 to 500°C; fluids not stable in this temperature range may require special treatment [1]. 3 3The italic numbers in brackets refer to the list of references at the end of this chapter.
Other approaches to determining molecular weight include distillation (gas chromatography) and mass spectroscopy. These are discussed separately.
Distillation Four distillation methods are in common use for determining the boiling range and for collecting fractions from viscous oils. ASTM Test Method D1160, Distillation of Petroleum Products at Reduced Pressure, 1 is probably the best known and most widely used of the methods for distillation of higherboiling petroleum products. The method is a vacuum distillation, applicable to samples that can be at least partially volatilized at temperature up to 400°C and pressure in the range 1 to 50 mm Hg. The distillation temperature at vacuum is converted to atmospheric equivalent temperatures. ASTM Test Method D447, Distillation of Plant Spray Oils/ is a method designed for characterization of these narrowboiling fractions. (Optimal persistence with minimal damage to plant fruit and foliage is obtained when narrow boiling petroleum fractions of appropriate volatility are used.) ASTM Test Method D2892, Distillation of Crude Petroleum (15-Theoretical Plate Column)/ applies to a wide range of products. The procedure uses a column with 15 theoretical plates and a 5"1 reflux ratio. The distillation is started at atmospheric pressure until the vapor temperature reaches 210°C. Distillation is continued at vacuum (100 mm Hg) until the vapor temperature again reaches 210°C or cracking is observed. With very heavy crudes or viscous products, a preferred alternate distillation method is ASTM Test Method D5236, Distillation of Heavy Hydrocarbon Mixtures (Vacuum Potstill Method). 1 This method should be used instead of ASTM D2892 for heavy crudes above a 400°C cutpoint. Unless a distillation method is required by specification or the collected fractions are needed for further testing, gas chromatographic methods have become preferred for determining the boiling range of petroleum fractions. ASTM Test Method D2887, Boiling Range Distribution of Petroleum Fractions by Gas Chromatography/ gives detailed information for samples with a final boiling point no higher than 538°C (1000°F) at atmospheric pressure and a boiling range greater than 55°C (100°F). Some laboratories have used modified procedures to analyze fractions boiling higher than 538°C. ASTM Subcommittee D02.04 has prepared a draft method that covers products boiling to 838°C; this method should be standardized in the near future.
Chemical Composition Elemental Analysis In elemental analysis of viscous oils, the analyst is most commonly interested in the presence of contaminant metals, nitrogen, and sulfur present in the hydrocarbon fraction. For finished products, additional information is sought regarding elements contributed by additives. While there exist many classical, wet chemical methods for determination of metals and certain elements, routine analysis generally involves instrumental methods based on spectrometric techniques including atomic absorption, emission, X-ray and plasma spectrometry.
C H A P T E R 4 - - A N A L Y S I S OF V I S C O U S O I L S Carbon and hydrogen are commonly determined by combustion analysis. There are numerous commercial instruments designed for this purpose. Generally, the sample is burned in an oxygen stream where carbon is converted to carbon dioxide and hydrogen to water. These compounds are absorbed and the composition is determined automatically from mass increase. Some instruments also measure nitrogen. ASTM Test Method D5291, Instrumental Determination of Carbon, Hydrogen and Nitrogen in Petroleum Products and Lubricants, 1 is a guide that summarizes general instructions to supplement manufacturers' instructions for their apparatus. It includes a list of recommended calibration standards for carbon, hydrogen, and nitrogen analyses.
Sulfur Sulfur is naturally present in many crude oils and petroleum fractions, most commonly as organic sulfides and heterocyclic compounds. Many refining steps aim to reduce this sulfur content to improve stability and reduce environmentally harmful emissions. Sulfur is also a component of wear-reducing and load-carrying additives, corrosion inhibitors, detergents, and emulsifiers. The methods used to measure sulfur content vary depending on the sulfur concentration, viscosity or boiling range, and presence of interfering elements. ASTM Test Method D129, Sulfur in Petroleum Products (General Bomb Method), 2 uses sample combustion in oxygen and conversion of the sulfur to barium sulfate, which is determined by mass. This method is suitable for samples containing 0.1 to 5.0 mass-% sulfur and can be used for most low-volatility petroleum products. Elements that produce residues insoluble in hydrochloric acid interfere with this method--this includes aluminum, calcium, iron, lead, and silicon, plus minerals such as asbestos, mica, and silica. For such samples, ASTM Test Method D1552, Sulfur in Petroleum Products (High Temperature Method), ~ is preferred. This method describes three procedures: the sample is first pyrolyzed in either an induction furnace or a resistance furnace; the sulfur is then converted to sulfur dioxide and either titrated with potassium iodate-starch reagent or the sulfur dioxide is analyzed by infrared spectroscopy. This method is generally suitable for samples containing from 0.06 to 8.0 mass-% sulfur and that distill at temperatures above 177°C. Two methods describe the use of X-ray techniques for sulfur determination. ASTM Test Method D2622, Sulfur in Petroleum Products by X-Ray Spectrometry, ~ can be used for samples with sulfur content of 0.001 to 5.0 mass-%. ASTM Test Method D4294, Sulfur in Petroleum Products by EnergyDispersive X-Ray Fluorescence Spectroscopy/ is useful at sulfur concentrations of 0.05 to 5.0 mass-%. Oil viscosity is not a critical factor with these two methods, but interference may affect test results when chlorine, phosphorus, heavy metals, and possibly silicon are present. For very low sulfur concentrations, a method that may be used is ASTM Test Method D4045, Sulfur in Petroleum Products by Hydrogenolysis and Rateometric Colorimetry? This is normally used for lower-viscosity fractions, but may be used for some viscous oils that boil below 371°C. The method is designed to measure sulfur in the range 0.02 to 10 mass-ppm.
27
Sulfur may also be determined along with metals by using ASTM Test Methods D4927, D4951, or D5185. These methods are described below under "Metals."
Nitrogen Nitrogen is present in viscous oils primarily as amines and heterocyclic ring compounds. Nitrogen is also a component of many additives used in petroleum products, including oxidation and corrosion inhibitors and dispersants. There are four ASTM standards describing analytical methods for nitrogen in viscous oils. ASTM Test Method D3228, Total Nitrogen in Lubricating Oils and Fuel Oils by Modified Kjeldahl Method, 4 is a standard wet chemical method. It is useful for determining the nitrogen content of most viscous oils in the range from 0.03 to 0.10 mass-%. The other three methods are instrumental techniques; one involves nitrogen reduction, the other two nitrogen oxidation. ASTM Test Method D3431, Trace Nitrogen in Liquid Petroleum Hydrocarbons (Microcoulometric Method), 5 is an instrumental method where nitrogen is pyrolyzed under reducing conditions and converted to ammonia, which is measured coulometrically. This method is very useful in assessing feeds for catalytic hydrogenation processes where nitrogen may act as a catalyst poison. ASTM Test Method D4629, Trace Nitrogen in Liquid Petroleum Hydrocarbons by Syringe/Inlet Oxidative Combustion and Chemiluminescence Detection/ is useful for samples containing 0.3 to 100 ppm nitrogen and boiling higher than 400°C but with viscosities of 10 cSt or less. Organic nitrogen is converted to NO and then to excited NO2 by reaction with oxygen and then ozone. Energy emitted during decay of the excited NO2 is measured with a photomultiplier tube. ASTM Test Method D5762, Nitrogen in Petroleum and Petroleum Products by Boat-Inlet Chemiluminescence, ~ is a complementary method suitable for more viscous samples that contain from 40 to 10,000 ppm nitrogen.
Metals The viscous fractions of crude oil often contain heavy metals such as iron, nickel, and vanadium. Catalytic refining processes are often sensitive to metal contamination and, therefore, the type and quantity of metals must be determined. In other cases such as lubricating oils, some metals are parts of compounds added to the petroleum component to enhance performance. Quantitative analysis for these metals is an important quality control step. ASTM Test Method D811, Chemical Analysis for Metals in New and Used Lubricating Oils, 6 is a standard wet cb_emical analysis method for aluminum, barium, calcium, magnesium, potassium, silicon, sodium, tin, and zinc. The procedure involves a series of chemical separations with specific elemental analysis performed using appropriate gravimetric or volumetric analyses. The method is very labor-intensive and is used primarily as a referee method or to calibrate standards for instrumental methods.
4Annual Book of ASTM Standards, Vol. 05.02. 5Discontinued; see 1993 Annual Book of ASTM Standards, Vol. 05.02. 6Discontinued; see 1989 Annual Book of ASTM Standards, Vol. 05.01.
28
MANUAL ON HYDROCARBON ANALYSIS
The most commonly used methods for determining metal content in viscous oils are spectroscopic techniques. Six ASTM standard methods exist that are applicable to viscous oils. Most methods permit simultaneous analysis of several elements; commercial instruments are readily available. Two use atomic absorption, one uses X-ray fluorescence, and three use inductively coupled plasma (ICP) spectroscopy. ASTM Test Method D4628, Analysis of Barium, Calcium, Magnesium and Zinc in Unused Lubricating Oils by Atomic Absorption Spectrometry, 1 is designed primarily for quality control analysis of additive metals in finished lubricants. The sample is diluted in kerosine and burned in an acetylenenitrous oxide flame of an AA spectrophotometer. The method is suitable for oils in the lubricating oil viscosity range. It is designed to measure barium at concentrations of 0.005 to 1.0 mass-%, calcium and magnesium at 0.002 to 0.3 mass-%, and zinc at 0.002 to 0.2 mass-%. Higher metal concentrations, such as are present in additives, can be determined by dilution. Lower concentrations in the range of 10 to 50 ppm can also be determined; however, the precision is poorer. An alternate test method is ASTM Test Method D4927, Elemental Analysis of Lubricant and Additive Components--Barium, Calcium, Phosphorus, Sulfur and Zinc by WavelengthDispersive X-Ray Fluorescence Spectroscopy. ~ The techniques are designed for unused lube oils containing metals at concentration levels from 0.03 to 1.0 mass-% and sulfur at 0.01 to 2.0 mass-%. Higher concentrations can be determined after dilution. A third technique is ASTM Test Method D4951, Determination of Additive Elements in Lubricating Oils by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP/AES). 1 Determined elements are barium, boron, calcium, copper, magnesium, phosphorus, sulfur, and zinc in unused lubricating oils and additive packages. Elements can generally be determined at concentrations of 0.01 to 1.0 mass-%. The sample is diluted in mixed xylenes or other solvents containing an internal standard. ASTM Test Method D5185, Determination of Additive Elements, Wear Metals and Contaminants in Used Lubricating Oils and Determination of Selected Elements in Base Oils by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP/AES),~ describes a modified ICP method. Although these methods are designed for used lubricating oils, they are also applicable to unused oils. Sensitivity and useable range varies from one element to another, but the method is generally applicable from 1 to 100 ppm for contaminants and up to 1000 to 9000 ppm for additive elements. The method covers: Additive Elements calcium magnesium phosphorus potassium sulfur zinc
aluminum barium boron chromium copper iron
Contaminant Elements lead sodium manganese tin molybdenum titanium nickel vanadium silicon silver
A third ICP method is ASTM Test Method D5708, Determination of Nickel, Vanadium and Iron in Crude Oils and Residual Fuels by Inductively Coupled Plasma (ICP) Atomic Emission Spectrometry. I Two procedures are described whereby the sample is either treated with acid to decompose
the organic material and dissolve the metals or, alternatively, the sample is dissolved in an organic solvent. The second procedure measures oil-soluble metals only and not insoluble particles. This inability to accurately measure metals in larger particles is true for many related methods. The method is sensitive down to about 1 ppm; the precision statement is based on samples containing i to 10 ppm iron, 10 to 100 ppm nickel, or 50 to 500 ppm vanadium. Finally, a second method provides an alternate method for analysis of crude oils and residuum: ASTM Test Method D5863, Determination of Nickel, Vanadium, Iron and Sodium in Crude Oils and Residual Fuels by Flame Atomic Absorption Spectrometry. 1 Pretreatment and limitations on determination of insoluble materials are identical to ASTM D5708. The sensitivity range is 3.0 to 10 ppm for iron, 0.5 to 100 ppm for nickel, 0.1 to 20 ppm for sodium, and 0.5 to 500 ppm for vanadium. Higher concentrations may be determined after dilution.
Miscellaneous E l e m e n t s Chlorine is present in some metalworking fluids as a chlorinated hydrocarbon or ester. It is less common in other viscous oils, but may be present in crude oils from brine contamination. Chlorine in lubricating oils can be determined using ASTM Test Method D808, Chlorine in New and Used Petroleum Products (Bomb Method), 2 or ASTM Test Method D1317, Chlorine in New and Used Lubricants (Sodium Alcoholate Method). 7 A rapid test method suitable for analysis of samples by non-technical personnel is ASTM Test Method D5384, Chlorine in Used Petroleum Products (Field Test Kit Method)? This method uses a commercial test kit where the oil sample is reacted with metallic sodium to convert organic halogens to halide, which is titrated with mercuric nitrate using diphenyl carbazone indicator. Iodides and bromides are reported as chloride. A special concern is contamination of viscous oils with polychlorinated biphenyls (PCBs). Electrical insulating oils require analysis before disposal to ensure the absence of PCBs. ASTM Test Method D6160, Determination of Polychlorinated Biphenyls (PCBs) in Waste Materials by Gas Chromatography, ~ is a newly introduced and widely applicable method. Standard reference samples for nine commercial PCBs (Aroclors) are available. Phosphorus is a common component of lubricating oil additives. It appears most commonly as a zinc dialkyl dithiophosphate or a tri-aryl phosphate ester, but other forms also occur. Two wet chemical methods are available. ASTM Test Method D1091, Test Methods for Phosphorus in Lubricating Oils and Additives, 2 describes an oxidation procedure that converts phosphorus to aqueous ortho-phosphate anion. This is then determined by mass as magnesium pyro-phosphate or photochemically as molybdi-vanadophosphoric acid. Phosphorus concentrations of 0.0002 to 20.0 mass-% can be accommodated by these procedures. An alternate test is ASTM Test Method D4047, Phosphorus in Lubricating Oils and Additives by Quinoline Phosphomolybdate Method. 4 Samples are oxidized to phosphate with zinc oxide, dissolved in acid, precipitated as quinoline phosphomolybdate, treated with excess standard alkali, and back-titrated with standard 7Discontinued; see 1994 Annual Book of ASTM Standards, Vol. 05.01.
CHAPTER 4--ANALYSIS OF VISCOUS OILS
29
acid. Both of these methods are primarily used for referee samples. Phosphorus is most commonly determined using X-ray fluorescence or ICP by ASTM Test Methods D4927 or D4951, which have been described previously under Metals.
mixture during processing. They are less reliable when comparing materials of different origin and can be very misleading when applied to atypical or unusual compositions.
Hydrocarbon Structure
A major use for gas chromatography for hydrocarbon analysis has been simulated distillation, as discussed previously. Other gas chromatographic methods have been developed for contaminant analysis. These include: ASTM Test Methods D3524, Diesel Fuel Diluent in Used Diesel Engine Oils by Gas Chromatography,1 and D4291, Trace Ethylene Glycol in Used Engine Oil. Column chromatography is used for several hydrocarbon type analyses that involve fractionation of viscous oils. Examples are: ASTM Test Methods D2007, Characteristic Groups in Rubber Extender and Processing Oils and Other Petroleum-Derived Oils by the Clay-Gel Absorption Chromatographic Method/ and D2549, Separation of Representative Aromatics and Nonaromatics Fractions of High-Boiling Oils by Elution Chromatography.~ ASTM D2007 uses absorption on clay and clay-silica gel, followed by elution of the clay with pentane to separate saturates; elution of clay with acetonetoluene to separate polar compounds; and elution of the silica gel fraction with toluene to separate aromatic compounds. ASTM D2549 uses absorption on a bauxite-silica gel column. Saturates are eluted with pentane; aromatics are eluted with ether, chloroform, and ethanol. A new method for hydrocarbon type analysis using supercritical fluid chromatography is under development by ASTM Subcommittee D02.04 and should be available shortly. Several promising chromatographic techniques have been reported for the analysis of lubricant base oils. Rod thin layer chromatography (TLC), high-performance liquid chromatography (HPLC), and supercritical fluid chromatography (SFC) have all been used for base oil analysis and base oil content [3-6 ]. Work to develop test methods is underway. Chromatographic methods are also extremely useful for isolation and identification of lubricant additives. Some recent papers reporting these techniques are available [7-9 ]. These methods have not yet been developed as standardized procedures.
Compositional analysis is concerned with determining structural relationships in the molecules present in a sample. Infrared spectroscopy is the most commonly used tool for qualitative chemical analysis of viscous oils. Descriptions and tables of characteristic absorbance for a variety of organic functional groups are readily available in many textbooks. Techniques for quantitative analysis for many additives and some hydrocarbon types are available, although few have been issued as ASTM standards. Reports on new methods are commonly reported in the chemistry literature. To locate information on new analytical methods, a most useful reference is the bi-annual Application Review published by the American Chemical Society. These have appeared recently in the June 15 issue of Analytical Chemistry in odd-numbered years. Recent reviews cover coal, crude oil, shale oil, heavy oils (natural and refined), lubricants, natural gas, and refined products and source rocks. Extensive references to original research papers are provided. A complimentary Fundamental Review covering the basic analytical techniques is published in even-numbered years. This review will emphasize those methods standardized by ASTM or under study within the committee.
Correlative Methods Correlative methods are derived relationships between fundamental chemical properties of a substance and measured physical or chemical properties. They provide information about an oil from readily measured properties. Examples of correlative methods of use with viscous oils are: ASTM Test Methods D2140, Carbon Type Composition of Insulating Oils of Petroleum Origin; a D2501, Calculation of Viscosity-Gravity Constant (VGC) of Petroleum Oils; ~D2502, Estimation of Molecular Weight (Relative Molecular Mass) of Petroleum Oils from Viscosity Measurements; ~ and D3238, Calculation of Carbon Distribution and Structural Analysis of Petroleum Analysis by the n-d-M Method. 4 D2501 describes the calculation of the viscosity-gravity coefficient. The VGC is a parameter derived from kinematic viscosity and density that has been found [2 ] to relate to the saturate/aromatic composition. D2502 permits estimation of molecular weight from kinematic viscosity measurements. This can be used with other properties to characterize hydrocarbon mixtures. ASTM D2140 and D3238 use correlations between the viscosity-gravity coefficient (or molecular weight and density) and refractive index to calculate carbon type composition in percent of aromatic, naphthenic, and paraffinic carbon atoms and an estimate of the number of aromatic and naphthenic rings present. Data from correlative methods must not be confused with more fundamental measurements obtained by chromatography or mass spectroscopy. Correlative methods can be extremely useful when used to follow changes in a hydrocarbon
8Annual Book of ASTM Standards, Vol. 10.03.
Chromatography
Spectrometric Methods Perhaps the most commonly used spectrometric method for analysis of viscous oils is infrared spectroscopy. General instructions for qualitative hydrocarbon type and functional group analysis are widely available. Papers have also been published for quantitative analysis of hydrocarbon types [10]. FT-IR techniques have been reported for use in predictive maintenance programs to monitor the concentration of additives and degradation products in used oils [11 ]. Two methods have been standardized using NMR for hydrocarbon characterization. An alternative to ASTM D5291 for determining hydrogen content of viscous oils is ASTM Test Method D4808, Hydrogen Content of Light Distillates, Middle Distillates, Gas Oils and Residua by Low Resolution Nuclear Magnetic Resonance Spectroscopy? The NMR method is simpler and more precise than techniques previously described in ASTM D5291. Procedures are described that cover light distillates with a 15 to 260°C boiling range, middle distillates and gas oils with boiling ranges of 200 to 370°C and 370 to 510°C, and residuum boiling above 510°C.
30
MANUAL ON H YD R O C A R B O N A N A L Y S I S
ASTM Test M e t h o d D5292, A r o m a t i c C a r b o n Contents of H y d r o c a r b o n Oils b y High Resolution N u c l e a r Magnetic Reso n a n c e Spectroscopy, 1 p e r m i t s d e t e r m i n a t i o n of a r o m a t i c h y d r o g e n a n d a r o m a t i c c a r b o n content of gas oils, lubricating oils, a n d other h y d r o c a r b o n fractions that are completely soluble in c h l o r o f o r m a n d c a r b o n t e t r a c h l o r i d e at a m b i e n t t e m p e r a t u r e s . Concentrations as low as 0.1 mol-% h y d r o g e n a n d 0.5 mol-% c a r b o n can be d e t e r m i n e d . Olefins a n d p h e n o lic c o m p o u n d s above 1 mass-% interfere. ASTM C o m m i t t e e D02 has s t a n d a r d i z e d three m e t h o d s for h y d r o c a r b o n c o m p o s i t i o n a l analysis using m a s s spectrometry. One of these is ASTM Test M e t h o d D2786, H y d r o c a r b o n Types Analysis of Gas-Oil S a t u r a t e s F r a c t i o n s by High Ionizing Voltage Mass S p e c t r o m e t r y ? A c o m p l e m e n t a r y m e t h o d is ASTM Test M e t h o d D3239, A r o m a t i c Types Analysis of Gas-Oil Aromatic F r a c t i o n s by High Ionizing Voltage Mass Spectrometry.1 These m e t h o d s require p r e l i m i n a r y sepa r a t i o n using elution c h r o m a t o g r a p h y , ASTM D2549, or similar method. A third m e t h o d , ASTM Test Method D2425, H y d r o c a r b o n Types in Middle Distillates by Mass Spectromet r y / m a y be applicable to s o m e viscous oil samples in the lower m o l e c u l a r weight range. The p r o c e d u r e s used in these m e t h o d s were originally developed a n d r e p o r t e d in 1969 [12 ]. They were developed using the Consolidated E l e c t r o d y n a m i c s Corp. Type 103 series (Model 21-100 a n d later the DuPont 21-103 a n d 21-104 instruments). These i n s t r u m e n t s are no longer in production. While n e w e r i n s t r u m e n t s are r e p o r t e d to give satisfactory results, the p r o c e d u r e s for their use have not been s t a n d a r d ized. Efforts are now in progress to provide test m e t h o d s using newer, lower-cost instruments. The use of q u a d r u p o l e i n s t r u m e n t s a n d a c o m b i n a t i o n of m a s s spectroscopy with gas or liquid c h r o m a t o g r a p h y should p r o d u c e useful new procedures.
FUTURE TRENDS As n o t e d in previous editions, the t r e n d in h y d r o c a r b o n analysis is away from m a n u a l test m e t h o d s a n d increasingly favors a u t o m a t e d i n s t r u m e n t a l methods. C o m m e r c i a l instrum e n t s are available that will p e r f o r m m a n y of the p r o c e d u r e s d e s c r i b e d in this chapter. While ASTM c o m m i t t e e s have stand a r d i z e d tests b a s e d on s o m e of these instruments, c o m m e r cial d e v e l o p m e n t is r a p i d a n d new analytical i n s t r u m e n t s are
constantly available. This t r e n d is expected to continue. A m a j o r challenge is to m a t c h s t a n d a r d test m e t h o d s with new e q u i p m e n t so that m e t h o d s do not b e c o m e obsolete. C o m b i n i n g s e p a r a t i o n a n d analysis techniques (hyphena t e d techniques) can p r o d u c e powerful tools for characterizing viscous oils. Thus, liquid c h r o m a t o g r a p h y o r gas c h r o m a t o g r a p h y can be used to s e p a r a t e a s a m p l e for subsequent c h a r a c t e r i z a t i o n by m a s s s p e c t r o m e t r y (LC/MS o r GC/MS). Research into suitable m e t h o d s for the analysis of viscous oils is underway, b u t no s t a n d a r d tests have yet b e e n prepared. Extensive r e s e a r c h on b o t h p r o t o n a n d carbon-13 nuclear m a g n e t i c r e s o n a n c e s p e c t r o s c o p y shows p r o m i s e as a tool for the analysis of lubricant base oils and other viscous oils. Both n e a r - i n f r a r e d spectroscopy (NIR) a n d F o u r i e r - t r a n s f o r m IR (FTIR) are the subjects of active research into m e t h o d s to characterize h y d r o c a r b o n s a n d for quality control d u r i n g p r o d u c t i o n of p e t r o l e u m products. S t a n d a r d test m e t h o d s using these techniques should b e c o m e available in the future.
REFERENCES [1 ] Coburn, J. F, "Lubricant Vapor Pressure Derived From Evaporation Loss," Transactions, American Society of Lubricating Engineers, ASLTA, Vol. 12, 1969, pp. 129-134. [2 ] Coats, H. B. and Hill, J. B., Industrial & Engineering Chemist~, Vol. 20, 1928, p. 641. [3 ] Barman, B. N., Journal of Chromatographic Science, Vol. 34, No. 5, 1996, pp. 219-225. [4 ] Sassiat, P. et al., Anal. Chim. Acta, Vol. 306, No. 1, 1995, pp. 73-79. [5 ] Kagdiyal, R. et al., Proceedings, Adv. Prod. Appl. Lube Base Stocks, 1994, pp. 295-302. [6 ] Jain, M. C. et al., Adv. Prod. Appl. Lube Base Stocks, 1994, pp. 272-279. [7] Hui, R. and Rosset, R.,Anal. Chim. Acta, Vol. 314, No. 3, 1995, pp. 1650-1657. [8 ] Machtalere, G. et al., Anal. Chim. Acta, Vol. 322, Nos. 1-2, 1996, pp. 31-41. [9 ] Lambroupoulos, N. et al., Journal of Chromatography, Vol. 749, Nos. 1-2, 1996, pp. 87-94. [10 ] Brandes, G., Brennstoff-Chemie, Vol. 37, 1956; Erdol und Kohle, Vol. 11, No. 10, 1958. [11 ] Powell, J. R. and Compton, D. A. C., Lub Eng., Vol. 49, No. 3, 1993, pp. 233-239. [12 ] Robinson, C. J. and Cook, G. L., Analytical Chemistry A, Vol. 41, 1969, p. 1548 ft.
Analysis of Waxes by Arthur D. Barker
INTRODUC~ON
ASTM Test Method D4419, Measurement of Transition Temperatures of Petroleum Waxes by Differential Scanning Calorimetry, 2 was produced in 1984 as a more accurate means of evaluating the melt characteristics of a wax. In the 1980s, ASTM D02.04 developed a gas chromatographic method, originally intended for the analysis of wax blends used in the rubber industry'. However, by the time the method was published, in 1993, the scope of the method had changed to ASTM Test Method D5442, Analysis of Petroleum Waxes by Gas Chromatography. 2 More recent innovations in nuclear magnetic resonance (NMR) instrumentation for measuring the oil content of waxes has led to the possibility of an alternative test to replace the lengthy ASTM Test Methods D721, Oil Content of Petroleum Waxes, 2 and D3235, Solvent Extractables in Petroleum Waxes. 2
PETROLEUM WAXES are the solid hydrocarbon residues remaining at the end of the refining process either in the lube stream (as mainly paraffin and intermediate waxes) or in the residual lube stock "tank bottoms" (as higher melting microcrystalline waxes). The waxy oil is fractionated to produce an oily wax, called slackwax. This is separated by solvent extraction and fractionated into different melting point ranges to give waxes with a variety of physical characteristics. Paraffin waxes consist mainly of straight chain alkanes (also called normal alkanes), with small amounts (3 to 15%) of branched chain alkanes (or iso-alkanes), cycloalkanes, and aromatics. Microcrystalline waxes contain high levels of branched chain alkanes (up to 50%) and cycloalkanes, particularly in the upper end of the molecular weight distribution. Paraffin waxes contain alkanes up to approximately 600 molecular weight, whereas microcrystalline waxes can contain alkanes up to 1100 molecular weight. Today refinery crude oils tend to be purchased from a variety of sources, which leads to variations in the wax products from the lube stream. Also paraffin and microcrystalline waxes have a large range of uses, either singly or as blends, or blended with other polymers. Therefore there is a need to characterize the refinery waxes, blended waxes, and end-user products. The main problems in characterizing waxes arise from the solid nature of the material and the difficulty in separating the material into its components, particularly in the case of microcrystalline waxes.
Gas Liquid Chromatography The separation of waxes on packed columns has been carried out since the 1960s [2,3 ], and capillary column chromatography was used in 1970 to separate a microcrystalline wax up to carbon chain length (also known as carbon number) n-Csa [4]. In the early 1980s, tire manufacturers requested ASTM D02.04 to produce a capillary column gas chromatography method to analyze rubber waxes (with oil content of less than 10%) from carbon number n-C~7 to n-C44. ASTM D02.10, the Subcommittee on Petroleum Wax, was asked by D02.04 to carry out the development of the method. By the time ASTM D5442 was issued, the scope of the method had been changed to encompass all petroleumderived waxes, including blends of waxes, from n-C17 to n-C44 using an n-Cl~ internal standard. The sample is diluted in a suitable solvent (cyclohexane is suggested), containing the n-C~6 internal standard. It is then injected into a capillary column, meeting a specified resolution, and the components are detected using a flame ionization detector. The eluted components are identified by comparison to a standard mixture containing every fourth alkane from n-Ct6 to n-C44. The resulting chromatogram is complex, and the area of each straight chain and branched chain alkane must be measured using a programmable integrator or computer chromatography software. ASTM Method D5442 outlines a complex procedure for measuring the amount of each n-alkane and associated iso-alkanes, which is difficult to carry out in an accurate manner. Immediately after the issuance of D5442, it was realized that the Scope of the method (alkanes from n-CI 7 to n-C44) was applicable only to the analysis of paraffin waxes, exclud-
CURRENT PRACTICES Analytical methods for waxes were originally based on physical tests, which are clearly explained in the ASTM Manual on Significance of Tests for Petroleum Products [1 ].1 Waxes are traded on the basis of the melting point range (e.g., 130 to 135°F melting point) as defined by ASTM Test Methods D87, Melting Point of Petroleum Wax (Cooling Curve), 2 or D127, Drop Melting Point of Petroleum Wax Including Petrolatum. 2 The growth in the reliability of sophisticated instrumentation has coincided with the need by wax blenders and users for more detailed "fingerprinting" of materials to obtain more precise quality control and detailed information. ~The italic numbers in brackets refer to references at the end of this chapter. 2Appears in this publication. 31
32 MANUAL ON H Y D R O C A R B O N A N A L Y S I S ing h i g h e r c a r b o n n u m b e r waxes. The availability of n-Cs0 a n d n-C60 s t a n d a r d s enables the m e t h o d to be extended to m i c r o c r y s t a l l i n e waxes. Also, the existing m e t h o d does not (1) take into account r e s e a r c h w o r k c a r r i e d out in the later p a r t of the 1980s on the effect of different integration methods that w o u l d result in i m p r o v e d a c c u r a c y of wax c h r o m a t o g r a p h y results a n d (2) include the use of p r o g r a m m a b l e t e m p e r a t u r e v a p o r i z e r (PTV) injectors [5,6]. The accurate quantitative analysis of microcrystalline waxes up to n-CT0 using the PTV injector was further amplified by Ludwig [7 ] in 1995 (30 years after his original p a p e r on w a x c h r o m a t o g r a p h y [3 ]). A review of the m e t h o d has t a k e n place, a n d it is h o p e d that a new r o u n d - r o b i n evaluation can be c a r r i e d out before the next revision of D5442 to validate (1) the use of the PTV injector, (2) use of the n-Cs0 a n d n-C60 standards, a n d (3) substitution of a new s i m p l e r calculation methodology.
An N M R m e t h o d has n o w b e e n developed, in conjunction with Oxford I n s t r u m e n t s , as a suitable alternative to ASTM Methods D721 a n d D3235. The N M R m e t h o d provides a r a p i d d e t e r m i n a t i o n of oil content, a unified m e t h o d for all wax oil content/solvent extractables analysis (covering the r a n g e 0.2 to 35% oil content), the exclusion of hot solvents, a n d it is easy to analyze the oil c o n t e n t of microcrystalline waxes. The c a l i b r a t i o n for this m e t h o d can n o w be c o m p a r e d with the present ASTM D721 b y using the LGC3004, 0.54% oil in wax s t a n d a r d CRM. A p r o p o s e d draft ASTM m e t h o d is being written for circulation a m o n g i n s t r u m e n t m a n u f a c t u r ers a n d users. It is h o p e d that the final draft will be jointed with the Institute of P e t r o l e u m a n d other s t a n d a r d i z a t i o n bodies so that a n i n t e r n a t i o n a l r o u n d r o b i n test can be carried out with sufficient participants.
FUTURE TRENDS
Oil Content Analysis During wax refining, increasing a m o u n t s of oil are removed, a n d this process needs to be controlled. Also, the oil content of slackwaxes, petrolatum, a n d waxes m u s t be assessed for end user specification. F o r high oil content waxes (i.e., greater t h a n 15%), ASTM Test M e t h o d D3235 was devised. This m e t h o d involves a lengthy p r o c e d u r e of dissolving a weighed a m o u n t of wax in a mixture of methyl ethyl ketone (MEK) a n d toluene, followed b y cooling to - 32°C to precipitate the wax. The oil a n d solvent are removed; then the solvent is e v a p o r a t e d off to p r o d u c e a weighable a m o u n t of oil. GLC analysis of the solvent-extracted m a t e r i a l has shown that the d e t e r m i n e d "oil" contains a small a m o u n t of additional wax, Y/-CI7to r/-C22 alkanes, t h e r e b y p r o d u c i n g a small error. ASTM Test M e t h o d D721 was devised for waxes containing less t h a n 15% oil. It is used in the specification of food-contact a p p r o v e d waxes a n d for waxes used in explosives. This m e t h o d is similar to ASTM D3235, b u t uses only M E K as the solvent. Both m e t h o d s take over half a day to complete, are l a b o r intensive, p r o d u c e variable results, a n d c a n n o t easily be used to analyze the oil content of microcrystalline waxes. This is not very useful for refinery process control, n o r for the analysis of wax m a t e r i a l s used in food-contact applications, etc. Refineries have o v e r c o m e this lengthy p r o c e d u r e by using various n u c l e a r m a g n e t i c r e s o n a n c e (NMR) techniques, calib r a t e d using waxes analyzed by either ASTM D721 o r D3235. In 1997 the UK L a b o r a t o r y of the G o v e r n m e n t Chemist (LGC) p r o d u c e d a wax certified reference m a t e r i a l with an oil content of 0.54% (Reference CRM:LGC 3004) [8]. This is useful as a n analytical quality control s t a n d a r d a n d overcomes the p r o b l e m of i n t e r l a b o r a t o r y disputes. Over the p a s t three years there has been a growing interest in the use of pulse NMR for the analysis of waxes for oil content. This technique relies on the fact that, after a wax has experienced a pulse of r a d i o - f r e q u e n c y radiation, the signals received f r o m the solid a n d liquid phases decay at different rates a n d that the a m p l i t u d e of each signal is p r o p o r t i o n a l to each p h a s e present. The solid signal decays r a p i d l y whereas the liqu!d signal lasts m u c h longer. The s a m p l e is cooled so that the wax is totally solid a n d the liquid signal is p r o p o r tional to the oil content.
In the next five years the p r o b l e m s associated w i t h the GLC analysis of waxes should be resolved, a n d there should be a n e w ASTM m e t h o d using N M R to m e a s u r e the oil content/ solvent extractables. Also, ASTM Test Method D4419 needs to be u p d a t e d a n d e x p a n d e d to i n c o r p o r a t e the m e a s u r e m e n t of wax enthalpy so t h a t the degree of crystallinity can be estimated. There also needs to be i m p r o v e m e n t s to ASTM Test M e t h o d D1833, Test M e t h o d for O d o r of Petroleum Wax, a w h i c h requires at least five people examining the o d o r of a wax u n d e r rigorous conditions. It is not a very practical test for small, m o d e r n laboratories. Solvent odors can be quantified by h e a d s p a c e GLC, but o t h e r odors, such as those due to oxidation, are m o r e complex a n d difficult to detect. F o r several years the possibility has b e e n explored of using a new type of i n s t r u m e n t a t i o n that consists of up of 32 sensors acting as an "electronic nose" to analyze h e a d s p a c e emissions. The responses from the multi-elements of the detector are complex a n d variable. Therefore, the electronic signals m u s t be processed as a neural network, a n d each a r o m a has to be "learned" by the software. These i n s t r u m e n t s are capable of m e a s u r i n g odors from individual waxes b u t will need further d e v e l o p m e n t to be of practical use for analyzing a variety of waxes. This example illustrates that there is still plenty of scope for the d e v e l o p m e n t of new m e t h o d s for the analysis of h y d r o c a r b o n s in waxes.
REFERENCES [1 ] Dyroff, G. V., Ed., Manual on Significance of Tests for Petroleum Products, Chap. 10, ASTM Manual Series MNL1, 6th ed., 1993. [2 ] Scott, C. G. and Rowel1, D. A., Nature, Vol. 187, 1960, p. 143. [3 ] Ludwig, F. J., Analytical Chemistry, Vol. 37, 1965, p. 1732. [4 ] Gouw, T. H., Whittemore, I. M., and Rentoft, R. E., Analytical Chemistry, Vol. 42, 1970, p. 1394. [5 ] Barker, A. D. in "Wax Chromatography--The 80's Crossroads," Petroanalysis '87, G. B. Crump, Ed., John Wiley & Sons Ltd., New York, 1988. [6 ] Barker, A. D., "The Chromatographic Analysis of Refined and Synthetic Waxes," Journal Chromatography Library, Vol. 56,
aAnnual Book of ASTM Standards, Vol. 05.01.
C H A P T E R 5 - - A N A L Y S I S OF W A X E S Chromatography in the Petroleum Indust~, E. R. Adlard, Ed., Elsevier Science B.V., New York, 1995. [7 ] Ludwig, Sr., F. J., Journal of Chromatography A., Vol. 718, 1995, p. 119.
33
[8 ] Petroleum Wax Oil Content CRM: Reference No. LGC 3004; Office of Reference Materials, Laboratory of the Government Chemist, Queens Road, Teddington, Middlesex, TW11 0LY, England.
Analysis of Crude Oils
6
by Axel J. Lubeck
INTRODUCTION
ently similar methods than are analyses on any single refined petroleum product except, possibly, gasoline. The overriding issue when performing comprehensive crude oil assays is economics. Crude oils are assayed to determine: (a) the slate of products that can be produced with a given refinery's process technology; (b) the processing difficulties that may arise as a result of inherent impurities; and (c) the downstream processing and upgrading that may be necessary to optimize yields of high-value, specification products. The analytical results are typically stored in an electronic database that can be accessed by computer models that generate refinery-specific economic valuations of each crude or crude slate (i.e., mixture of crudes processed together). Analyses are also performed to determine whether each batch of crude oil received at the refinery gate meets expectations. Does the crude receipt match the database assay so that the projected economic valuations and operational strategies are valid? Has any unintentional contamination or purposeful adulteration occurred during gathering, storage, or transport of the crude oil that may increase the processing cost or decrease the value of the refined products? The information needed to answer these questions is often refinery-specific--a function of the refinery's operating constraints and product slate. To obtain the desired information, two different analytical schemes are commonly used, namely, an inspection assay and a comprehensive assay. Inspection assays usually involve determination of a few key whole crude oil properties such as API gravity, sulfur content, and pour point--principally as a means of determining if major changes in a crude oil stream's characteristics have occurred since the last comprehensive assay was performed. Additional analyses may be performed to help ensure that the cargo or shipment received is that which is expected; to ascertain the quantity of impurities such as salt, sediment, and water; and to provide other critical refinery-specific information. Inspection assays are routinely performed on all shipments received at a refinery. The comprehensive assay, on the other hand, is complex, costly, and time-consuming and is normally performed only when a new field comes on stream, or when the inspection assay indicates that significant changes in the stream's composition have occurred. Except for these circumstances, a comprehensive assay of a particular crude oil stream may not be updated for several years.
CRUDE OILS are a highly complex combination of hydrocarbons; heterocyclic compounds of nitrogen, oxygen, and sulfur; organometallic compounds; inorganic sediment; and water. Approximately 600 different hydrocarbons have been identified in crude oil, and it is likely that thousands of compounds occur, many of which probably will never be identified. In a study sponsored by the American Petroleum Institute (API), nearly 300 individual hydrocarbons were identified in Ponca City, Oklahoma crude oil [1,2 ].2 Some 200 individual sulfur compounds were identified in a 20-year systematic study of four crude oils [3 ]. Not only is the composition of crude oil highly complex, it is also highly variable from field-to-field, and even within a given field it is likely to exhibit inhomogeneity. Physical and chemical characterization of this complex mixture is further complicated for the analyst by the fact that crude oils are not pure solutions, but commonly include colloidally suspended components, dispersed solids, and emulsified water. Compared to refined products such as gasoline and aviation turbine fuel, there is relatively little in the literature on the analysis and characterization of crude oils. Indeed, for many years, there were relatively few ASTM methods specific to crude oils, although a number of ASTM methods had been adapted for use in analyzing crudes. This situation may have resulted, at least in part, from the historical tendency of refinery chemists to independently develop or modify analytical methods specific to their needs and subsequently for the methods to become company proprietary. In recent years, the unique problems associated with sampling and analysis of crude oils have received more attention, and more methods for determining selected constituents and characteristics of crude oils are now being standardized. A series of articles [4-9 ] illustrate the diversity of crude oil assay practices employed by major refiners in the United States and Austria. The dissimilarity of results reported in the literature [10 ] is a reflection of this independent development of analytical schemes, even though standardized approaches to crude oil analysis have previously been published [11,12 ]. Despite the complexity of crude oil composition and the diversity of analytical methodology, probably more crude oil analyses are routinely performed on a daily basis using inher~This chapter is an updated and modified version of the chapter, authored by H. N. Giles, found in the previous edition of this manual. 2The italic numbers in brackets refer to the list of references at the end of this chapter. 34
CHAPTER 6 - - A N A L Y S I S OF CRUDE OILS
CURRENT PRACTICES Inspection Assays Inspection assays comprise a limited number of tests generally restricted to the whole crude oil. Based on published data, there is little agreement as to what constitutes an inspection assay. As the data are primarily for intra-company use, there is little driving force for a standard scheme. At a bare minimum, API gravity and sulfur content are usually determined, although it is useful to also know the pour point, which provides some basic perception of the crude oil's aromaticity. A more detailed inspection assay might consist of the following tests: API gravity (or density or relative density), total sulfur content, pour point, viscosity, salt content, and water and sediment content. Individual refiners may substitute or add tests (e.g., trace metals or organic halides) that may be critical to their operations. Coupling the results from these few tests of a current crude oil batch with the archived data from a comprehensive assay, the process engineer will be able to estimate generally the product slate that the crude will yield and any extraordinary processing problems that may be encountered.
API Gravity Accurate determination of the gravity of crude oil is necessary for the conversion of measured volumes to volumes at the standard temperature of 15.56°C (60°F) (ASTM D1250, Petroleum Measurement Tables). 3 Gravity is also a factor reflecting the quality of crude oils. API gravity is a special function of relative density (specific gravity) represented by the following: API gravity, deg -- (141.5/sp gr 60/60°F) - 131.5 API gravity, or density or relative density, can be determined easily using one of two hydrometer methods [ASTM Test Method D287, API Gravity of Crude Petroleum and Petroleum Products (Hydrometer Method) 3 or ASTM Test Method D1298, Density, Relative Density (Specific Gravity) or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method ].3 An instrumental method that is finding increasing popularity (ASTM Test Method D5002, Density and Relative Density of Crude Oils by Digital Density Analyzer)3 may also be used.
35
a sample in oxygen to convert the sulfur to sulfur dioxide, which is collected and subsequently titrated iodometrically or detected by non-dispersive infrared [ASTM Test Method D1552, Sulfur in Petroleum Products (High-Temperature Method) ].3 An even older method involving combustion in a bomb with subsequent gravimetric determination of sulfur as barium sulfate [ASTM Test Method D129, Sulfur in Petroleum Products (General Bomb Method)]4 is not as accurate as the high-temperature method, possibly because of interference from the sediment inherently present in crude oil. The older, classical techniques are being supplanted by two instrumental methods (ASTM Test Method D4294, Sulfur in Petroleum Products by Energy-Dispersive X-Ray Fluorescence Spectroscopy and ASTM Test Method D2622, Sulfur in Petroleum Products by X-Ray Spectrometry). 3 D4294 has slightly better repeatability and reproducibility than the hightemperature method and is adaptable to field applications; however, this method can be affected by some commonly present interferences such as halides. D2622 has even better precision and the capability of correcting for interferences, but is currently limited to laboratory use, and the equipment is more expensive. Hydrogen sulfide and mercaptans are commonly determined by non-aqueous potentiometric titration with silver nitrate [13 ].
Salt Content The salt content of crude oil is highly variable and results principally from production practices used in the field and, to a lesser extent, from its handling aboard tankers bringing it to terminals. The bulk of the salt present will be dissolved in coexisting water and can be removed in desalters, but small amounts of salt may be dissolved in the crude oil itself. Salt may be derived from reservoir or formation waters, or from other waters used in secondary recovery operations. Aboard tankers, ballast water of varying salinity may also be a source of salt contamination. Salt in crude oil may be deleterious in several ways. Even in small concentrations, salts will accumulate in stills, heaters, and exchangers leading to fouling that requires expensive cleanup. More importantly, during flash vaporization of crude oil certain metallic salts can be hydrolyzed to hydrochloric acid according to the following reactions: 2NaC1 + H20--~ 2 HC1 + Na20
Sulfur Content The sulfur content of a crude oil, which may vary from less than 0.1 to over 5 mass-%, is one of its most important quality attributes. Sulfur compounds contribute to corrosion of refinery equipment and poisoning of catalysts, cause corrosiveness in refined products, and contribute to environmental pollution as a result of the combustion of fuel products. Sulfur compounds may be present throughout the boiling range of crude oils although, as a rule, they are more abundant in the heavier fractions. In some crude oils, thermallylabile sulfur compounds can decompose on heating to produce hydrogen sulfide that is highly toxic and very corrosive. Until recently, one of the most widely used methods for determination of total sulfur content has been combustion of 3Appears in this publication.
MgC12 + H20--* 2 HCI + MgO The hydrochloric acid evolved is extremely corrosive, necessitating the injection of a basic compound, such as ammonia, into the overhead lines to minimize corrosion damage. Salts and evolved acids can also contaminate both overhead and residual products, and certain metallic salts can deactivate catalysts. A thorough discussion of the effects of salt on crude processing is included in a manual on impurities in petroleum [14 ]. The salt content is routinely determined by comparing the conductivity of a solution of crude oil in a polar solvent to that of a series of standard salt solutions in the same solvent [ASTM Test Method D3230, Salts in Crude Oil (Electrometric
4Annual Book of ASTM Standards, Vol. 05.01.
36
MANUAL ON H YD R O C A R B O N A N A LYSI S
Method)]. 3 It is necessary, however, to employ other methods, such as atomic absorption, inductively-coupled argon plasma spectrophotometry, and ion-chromatography to determine the composition of the salts present.
Water and Sediment The water and sediment content of crude oil, like salt, results from production and transportation practices. Water, with its dissolved salts, may occur as easily removable suspended droplets or as an emulsion. The sediment dispersed in crude oil may be comprised of inorganic minerals from the production horizon or from drilling fluids, and scale and rust from pipelines and tanks used for oil transportation and storage. Usually water is present in far greater amounts than sediment but, collectively, it is unusual for them to exceed one percent of the crude oil on a delivered basis. Like salt, water and sediment can foul heaters, stills, and exchangers and can contribute to corrosion and to deleterious product quality. Also, water and sediment are principal components of the sludge that accumulates in storage tanks and must be disposed of periodically in an environmentally acceptable manner. Knowledge of the water and sediment content is also important in accurately determining net volumes of crude oil in sales, taxation, exchanges, and custody transfers. A number of methods exist for the determination of water and sediment in crude oil. Centrifugal separation of the water and sediment [ASTM Test Methods D96, Water and Sediment in Crude Oil by Centrifuge Method (Field Procedure) or D4007, Water and Sediment in Crude Oil by the Centrifuge Method (Laboratory Procedure)]a is rapid, relatively inexpensive, and adaptable to field conditions but, almost invariably, the amount of water detected is lower than the actual water content. A more accurate method for sediment entails extraction with hot toluene in a refractory thimble (ASTM Test Method D473, Sediment in Crude Oils and Fuels Oils by the Extraction Method).3 Improved techniques for measuring water content include heating under reflux conditions with a water immiscible solvent that distills as an azeotrope with the water (ASTM Test Method D4006, Water in Crude Oil by Distillation), 3 potentiometric titration (ASTM Test Method D4377, Water in Crude Oils by Potentiometric Karl Fischer Titration), 3 or the more generally preferred coulometric titration (ASTM Test Method D4928, Water in Crude Oils by Coulometric Karl Fischer Titration). 3 The latter two Karl Fischer methods include a homogenization step designed to re-disperse any water that has separated from the crude oil since the original sample was taken.
Pour Point and Viscosity Pour point and viscosity determinations of crude oils are performed principally to ascertain their handling characteristics at low temperatures. There are, however, some general relationships about crude oil composition that can be derived from pour point and viscosity data. Commonly, the lower the pour point of a crude oil the more aromatic it is, and the higher the pour point, the more paraffinic it is. There are numerous exceptions to this rule-of-thumb, and other data must be used to verify a crude oil's character. Probably the most widely used index is the Characterization or K Factor [15 ], which was originally defined as the cube root of the average molal boiling point in °F absolute (Rankine) tempera-
ture divided by the specific gravity, at 60/60°F. It has conveniently been related to viscosity and API gravity [16 ]. Typically, paraffin base crudes have K > 12.2, intermediate base crudes have K values of 11.4 to 12.2, and naphthene base crudes have K < 11.4 [17 ]. Pour point is determined by cooling a preheated sample at a specified rate and examining its flow characteristics at intervals of 3°C (ASTM Test Method D5853, Pour Point of Crude Oils). 3 Viscosity is determined by measuring the time for a volume of liquid to flow under gravity through a calibrated glass capillary viscometer [ASTM Test Method D445, Kinematic Viscosity of Transparent and Opaque Liquids (and the Calculation of Dynamic Viscosity)]. 3 Tables are available for converting kinematic viscosity in centistokes at any temperature to Sayholt Universal viscosity in Sayhoh Universal seconds at the same temperature, and for converting kinematic viscosity in centistokes at 122 and 210°F to Saybolt Furol viscosity in Saybolt Furol seconds at the same temperatures (ASTM Method D2161, Conversion of Kinematic Viscosity to Sayholt Universal Viscosity or to Saybolt Furol Viscosity). 4 By determining viscosity at two temperatures such as 25 and 37.78°C, viscosity at any other temperature over a limited range may be interpolated or extrapolated using viscosity-temperature charts (ASTM D341, Viscosity-Temperature Charts for Liquid Petroleum Products). 3
Trace Elements A number of trace elements have been detected in crude oil but, aside from nickel and vanadium, which are usually the most abundant, relatively little systematic analytical work has been carried out. Over 30 trace metals are known to occur naturally in crude oils [l&19] and, with the increasing sophistication of analytical methodology, it is likely that other elements will be detected. Knowledge of the trace element constituents is important because they can have an adverse effect on petroleum refining and product quality. Elements such as iron, arsenic, and lead are catalyst poisons. Vanadium compounds can cause refractory damage in furnaces, and sodium compounds have been found to cause superficial fusion on fire bricks [20 ]. Some organometallic compounds are volatile, which can lead to contamination of distillate fractions [21 ] and a reduction in their stability or malfunctions of equipment when they are combusted. Concentration of the non-volatile organometallics in heavy products (e.g., premium coke) can have a significant impact on price, salability, and use. Several analytical methods are available for the routine determination of trace elements in crude oil, some of which allow direct aspiration of the samples (diluted in a solvent) instead of the time-consuming sample preparation procedures such as wet ashing (acid decomposition) or flame or dry ashing (removal of volatile/combustible constituents). Among the techniques used for trace element determinations are flameless and flame atomic absorption (AA) spectrophotometry (ASTM Test Method D5863, Determination of Nickel, Vanadium, Iron, and Sodium in Crude Oils and Residual Fuels by Flame Atomic Absorption Spectrometry) 3 and inductively-coupled argon plasma spectrophotometry [ASTM Test Method D5708, Determination of Nickel, Vanadium, and Iron in Crude Oils and Residual Fuels by Inductively-Coupled Plasma (ICP) Atomic Emission Spectrometry]. 3 ICP has an
CHAPTER 6--ANALYSIS OF CRUDE OILS advantage over AA because it can determine a number of elements simultaneously, although detection limits by AA are often better. X-ray fluorescence spectrophotometry is also sometimes used, although matrix effects can be a problem. The method to be used is generally a matter of individual preference.
Other Tests Other properties that are determined on a more limited basis include the following:
Vapor Pressure--[ASTM Test Method D323, Vapor Pressure of Petroleum Products (Reid Method) or ASTM D5191, Vapor Pressure of Petroleum Products (Mini Method)]) Total Acid Number--to provide an indication of the naphthenic acids content (ASTM Test Method D664, Acid Number of Petroleum Products by Potentiometric Titration). 3 Carbon Residue--amount left after evaporation and pyrolysis to provide some indication of relative coke-forming propensity (ASTM Test Method D189, Conradson Carbon Residue of Petroleum Products, ASTM Test Method D524, Ramsbottom Carbon Residue of Petroleum Products, or ASTM Test Method D4530, Determination of Carbon Residue (Micro Method)), 3 ASTM Method D4530 having gained wide acceptance. Total Nitrogen Content--(ASTM Test Method D3228, Total Nitrogen in Lubricating Oils and Fuel Oils by Modified Kjeldahl Method), 5 (ASTM Test Method D4629, Trace Nitrogen in Liquid Petroleum Hydrocarbons by Syringe/ Inlet Oxidative Combustion and Chemiluminescence Detection, ASTM Test Method D5762, Nitrogen in Petroleum and Petroleum Products by Boat-Inlet Chemiluminescence)) Organic Chloride Content--by distillation and sodium biphenyl reduction or microcoulometry (ASTM Test Method D4929, Determination of Organic Chloride Content in Crude Oil). 3 Waxes and Asphaltenes--by solvent extraction; and determination of optical density color by spectrophotometrically measuring the absorbance of a solution of the crude oil in isooctane (2,2,4-trimethylpentane) or other suitable solvent. With increasing frequency, refinery engineers desire an estimate of the distillation yields of a crude oil. These can be provided rapidly, without the performance of a conventional pot distillation, using gas chromatography (ASTM Test Method D5307, Determination of the Boiling Range Distribution of Crude Petroleum by Gas Chromatography). 3 The inspection assay tests discussed above are undoubtedly not exhaustive, but are the ones most commonly used. These tests will provide the refiner with data on the impurities present and a general idea of the products that may be recoverable. However, they will not provide the data essential to determining whether a given crude oil or blend of crude oils will yield an economically attractive product slate. This requires that a comprehensive assay be performed.
SAnnual Book of ASTM Standards, Vol. 05.02.
37
Comprehensive Assays In addition to the whole crude oil tests performed as part of the inspection assay, a comprehensive or full assay requires that the crude be fractionally distilled and the fractions characterized by appropriate tests. This is necessary so that the refiner can assess the quantity and quality of products recoverable from a given crude oil and determine if that product slate economically satisfies the market requirements of a particular refinery. Refiners tailor a comprehensive assay to their individual needs, and the number of cuts or fractions taken may vary from as few as 4 to as many as 24. The following eight fractions will provide the basis for a moderately thorough evaluation: C2-C5 C5-79°C 79-121°C 121-191°C 191-277°C 277-343°C 343-566°C 566°C +
Gas Light naphtha Medium naphtha Heavy naphtha Kerosine Distillate fuel oil Gas oil or lube stock Residuum
Commonly, from five to 50 L of crude oil will be needed for a comprehensive assay, depending on the number of cuts to be taken and the tests to be performed on the fractions. Fractionation of the crude oil begins with a true boiling point (TBP) distillation employing a fractionating column having an efficiency of 14 to 18 theoretical plates and operated at a reflux ratio of 5 : 1 [ASTM Test Method D2892, Distillation of Crude Petroleum (15-Theoretical Plate Column)]) The TBP distillation may be used for all fractions up to a maximum cut point of about 350°C atmospheric equivalent temperature (AET), provided reduced pressure is used to minimize cracking. Beyond an AET of 350°C, it is necessary to continue the distillation at further reduced pressures under conditions that provide approximately a one-theoretical plate fractionation (ASTM Test Method D1160, Distillation of Petroleum Products at Reduced Pressure). 3 This fractionation may be continued up to a maximum liquid temperature of approximately 400°C at a pressure of 0.13 kPa (1 mm Hg)(640°C AET) provided significant cracking does not occur. In 1992 a new standard was published [ASTM Test Method D5236, Distillation of Heavy Hydrocarbon Mixtures (Vacuum Potstill Method)]3 that is seeing increasingly more use and appears to be supplanting D 1160 as the method of choice for crude assay vacuum distillations. Wiped-wall or thin-film molecular stills can also be used to separate the higher boiling fractions under conditions that minimize cracking. In these units, however, cut points cannot be directly selected, because vapor temperature in the distillation column cannot be measured accurately under operating conditions. Instead, the wall (film) temperature, pressure, and feed rate that will produce a cut equivalent to a D 1160 (or D5236) fraction with a given end point are determined from in-house correlations developed by matching yields between the wiped-wall distillation and the D1160 (or D5236) distillation. Despite the indirect approach, wiped-wall stills are often used because they allow higher end points than the D1160 or D5236 test methods and can easily provide large quantities of material for characterization.
38
MANUAL ON HYDROCARBON ANALYSIS
Following fractionation of the crude oil, each of the fractions is analyzed to determine one or more of its physical or chemical characteristics depending on the needs of the refiner. All of the various tests that could be performed on each of the fractions are too numerous to be included here. In the following discussion, the properties or constituents generally measured in a detailed analysis of each of the above eight fractions are listed. Gas
Typically, the gas or debutanization fraction is analyzed by high-resolution gas chromatography for quantitative determination of individual C2 to C4 and total C5 ÷ hydrocarbons. Relative density (specific gravity) can be calculated from the compositional analysis.
Light Naphtha Density or specific gravity by hydrometer or (ASTM Test Method D4052, Density and Relative Density of Liquids by Digital Density Meter), 3 total sulfur (ASTM Test Method D2622, ASTM Test Method D3120, Trace Quantities of Sulfur in Light Liquid Petroleum Hydrocarbons by Oxidative Microcoulometry, or ASTM Test Method D5453, Determination of Total Sulfur in Light Hydrocarbons, Motor Fuels, and Oils by Ultraviolet Fluorescence), 3 mercaptan sulfur [ASTM Test Method D3227, Mercaptan Sulfur in Gasoline, Kerosine, Aviation Turbine, and Distillate Fuels (Potentiometric Method)], 3 hydrogen sulfide, and organic chlorides are typically determined on this fraction. Because this fraction is important both as a petrochemical feedstock and as a gasoline blending component, it is likely that it would also be analyzed by high-resolution gas chromatography for quantitative determination of its paraffin, isoparaffin, aromatic, naphthene (cycloparaffin), and olefin, if any, components (PIANO analysis). Octane numbers would also be determined for this fraction if it were to be included as a gasoline blending component. Typically, octane numbers are determined using special engines that require relatively large volumes of sample (ASTM Test Method D2699, Knock Characteristics of Motor Fuels by the Research Methods and ASTM Test Method D2700, Knock Characteristics of Motor and Aviation Fuels by the Motor Method). 6 Some companies are now using semi-micro methods that require considerably less sample than the above standard methods for determination of octane numbers [22 ]. Other laboratories use PIANO data to calculate octane numbers [5 ].
Medium and Heavy Naphthas Density or specific gravity, total sulfur, mercaptan sulfur, hydrogen sulfide, organic chloride, and PIANO determinations would normally be determined on these fractions. Included in the information that can be derived from the PIANO analysis are the concentrations of benzene and benzene precursors (compounds that ultimately form benzene in a refinery's reforming unit). These data are important because of governmental regulations limiting the maximum concentration of benzene in reformulated gasoline. 6Annual Book of ASTM Standards, Vol. 05.04.
Kerosine Typically, density or specific gravity, total sulfur, mercaptan sulfur, hydrogen sulfide, aniline point (ASTM Test Method D611, Aniline Point and Mixed Aniline Point of Petroleum Products and Hydrocarbon Solvents), 3 total acid or neutralization number, naphthalenes content (ASTM Test Method D 1840, Naphthalene Hydrocarbons in Aviation Turbine Fuels by UV Spectrophotometry), 3 smoke point (ASTM Test Method D1322, Smoke Point of Aviation Turbine Fuels), 3 total nitrogen (see Note 1), viscosity, and freezing point (ASTM Test Method D2386, Freezing Point of Aviation Fuels) 3 would be determined for this fraction and a cetane index calculated (ASTM Test Method D976, Calculated Cetane Index of Distillate Fuels or ASTM Test Method D4737 for Calculated Cetane Index by Four Variable Equation). 3 Other tests that might be performed, depending on the intended end use of the fraction, are flash point (ASTM Test Method D56, Flash Point by Tag Closed Tester), 3 corrosiveness (ASTM Method D130, Detection of Copper Corrosion from Petroleum Products by the Copper Strip Tarnish Test), 3 and thermal stability [ASTM Test Method D3241, Thermal Oxidation Stability of Aviation Turbine Fuels (JFTOT Procedure)] .3
Note 1--In general, the ratio of basic to total nitrogen is practically constant at 0.3:1 for crude oils and virgin stocks. It also appears that the types of nitrogen compounds present in various crude oils are essentially the same, although the actual amounts may vary considerably [23 ]. Consequently, in most assays it is sufficient to determine total nitrogen (by the modified Kjeldahl or chemiluminescence methods).
Distillate Fuel Oil Tests of the fuel oil fraction normally include determination of density or specific gravity, total sulfur, aniline point, total acid number, naphthalenes content, smoke point, total nitrogen, viscosity, cloud point (ASTM Test Method D2500, Cloud Point of Petroleum Oils), 3 pour point (ASTM Test Method D97, Pour Point of Petroleum Oils), 3 and calculation of cetane index. Corrosiveness, ash (ASTM Test Method D482, Ash from Petroleum Products), 3 and carbon residue might also be determined in more thorough evaluations.
Gas Oil and Lube Stocks Density or specific gravity, total sulfur, aniline point, total nitrogen, viscosity, cloud point, pour point, trace metals (Fe, Ni, V), and carbon residue would normally be determined on this fraction. If the fraction is to be used as catalytic cracker feedstock, asphaltenes would also be determined by precipitation with normal-heptane (ASTM Test Method D3279, Heptane Insolubles). 3 Wax content determination by solvent reflux [24 ] might be included in a lube stock evaluation. Hydrocarbon-type analysis by mass spectrometry or other means is an important part of lube stock evaluation, but this is beyond the scope of this chapter.
Residuum Tests of the residuum typically include density or specific gravity, total sulfur, total nitrogen, viscosity, trace metals, and carbon residue. Determination of the properties of asphalt such as penetration (ASTM Test Method D5, Penetra-
C H A P T E R 6 - - A N A L Y S I S OF C R U D E O I L S tion of Bituminous Materials), 3 softening point [ASTM Test Method D36, Softening Point of Bitumen (Ring-and-Ball Apparatus) ],3 and viscosity (ASTM Test Method D2171, Viscosity of Asphalts by Vacuum Capillary Viscometer or ASTM Test Method D3205, Viscosity of Asphalt with Cone and Plate Viscometer) 3 would also be included in some assays. However, new specifications for asphalt have been developed by the Strategic Highway Research Program (SHRP) and test methods are being standardized by the American Association of State Highway and Transportation Officials (AASHTO) and ASTM. These test methods will replace some of the existing asphalt test methods as states adopt the SHRP specifications. The tests listed for each fraction and for the whole crude oil assay are not exhaustive but are illustrative of those used to evaluate quality. A more thorough discussion [25 ] of the significance of many of the above tests, as well as methods for the assessment of product quality, is available. As noted earlier, refiners tailor their analytical scheme to their particular crude oil and product slates, although one refiner is reported to have said "The best crude oil assay is a 100,000 bbl run through my refinery" [26 ]. While this opinion carries some validity, the assay methods presented here provide quantity and quality data that are sufficient for most refiners to evaluate crude oil streams, and, in some instances, assay information is the ounce of prevention that precludes the need for a refinery to apply the pound of cure. With the proliferation of computer "assay" programs [9 ], many refiners no longer need to perform comprehensive assays as frequently as in the past. An inspection assay is all that is required for them to anticipate and plan for processing problems that will be caused by varying levels of impurities in the crude oil stream.
FUTURE TRENDS The crude oils being processed in refineries are on average becoming increasingly heavier (more residuum) and more sour (higher sulfur content). To produce a viable product slate with these crudes, refiners must add to or expand existing treatment and processing options. The high sulfur content of crude coupled with government regulations limiting the maximum sulfur content of fuels makes sulfur removal a priority in refinery processing. In addition, refinery economics dictate that the "bottom of the barrel" (residuum) must be upgraded to higher value products. New treatment and process units in the refinery usually translate into a need for new analytical test methods that can adequately evaluate feedstocks and monitor product quality. Sulfur reduction processes are sensitive to both amount and structure of the sulfur compounds being removed. Tests that can provide information about both are becoming increasingly important. A number of laboratories have combined the separation power of gas chromatography with sulfur-selective detectors to provide data on the boiling range distribution of the sulfur compounds and probable molecular types, as well. A method (ASTM Test Method D5623, Sulfur Compounds in Light Petroleum Liquids by Gas Chromatography and Sulfur Selective Detection) 3 has been standardized for sulfur compounds in the gasoline boiling range. Work on extending this type of analysis to higher boiling ranges is on-
39
going. In addition, gas chromatography detectors that provide selectivity for other constituents of interest (e.g., nitrogen, organometallics) are also available and being used for characterization. Upgrading the "bottom of the barrel" involves taking more (ideally all) of the residuum and processing it into a more salable, higher valued product. Whatever the means to this end, improved characterization methods are necessary for process design, crude oil evaluation, and operational control. Among the characterization methods under development by industry, instrument vendor, and commercial laboratories are ones that define the boiling range and the hydrocarbontype distribution. Boiling range distribution of heavy distillates and residua are increasingly being carried out by hightemperature simulated distillation (HTSD) by gas chromatography. An HTSD test method applicable to distillates with end points up to 700°C is currently in the balloting process as a proposed ASTM standard. A separate HTSD method is in use for residuum-containing materials, including crude oils [27 ]. This method provides a quantitative boiling range distribution (that accounts for non-eluting components) in a single analysis as opposed to two analyses required by D5307. However, the method has not yet been submitted to ASTM for standardization. The distributions of hydrocarbon types in gas oil and heavier materials are important in evaluating them as feedstocks for further processing. Some ASTM member laboratories are working to update older mass spectrometric methods for determining hydrocarbon types (ASTM Test Method D3239, Aromatic Types Analysis of Gas-Oil Aromatic Fractions by High Ionizing Voltage Mass Spectrometry and ASTM Test Method D2786, Hydrocarbon Types Analysis of Gas Oil Saturates Fractions by High Ionizing Voltage Mass Spectrometry) 3 for use with modern quadrupole mass spectrometers, either with batch inlets or with gas chromatographic inlets (GC/MS). Another technique that has been successfully applied for determining hydrocarbon types in these materials involves use of high-performance liquid chromatography [28]. Providing comparable information to the mass spectrometric methods, the HPLC method is yet to be submitted to ASTM for standardization. From the examples above, it is obvious that automated, instrumental analyses continue to be the option of choice when developing new methods. There is no indication that this propensity will wane. The primary motivation for this trend, if anything, is increasing. Labs are continually seeking to reduce analysis time (especially analyst's time) and improve the quality of test results (in these cases by eliminating dependency on the manual skills of the analyst). Fueled by rapid advances in technology, more of the same is expected as the analytical challenges of the industry are met.
REFERENCES [l ] Rossini, F. D.. "Hydrocarbons in Petroleum," Journal of Chemical Education, Vol. 37, 1960, pp. 554-561. [2 ] Mair, B. J., "Annual Report for the Year Ending, June 30, 1967," American Petroleum Institute Research Project 6" Pittsburgh, PA, Carnegie Institute of Technology, 1967. [3 ] Rail, H.T., Thompson, C.J., Coleman, H.J., and Hopkins, R. L., "Sulfur Compounds in Oil," Bulletin 659, U.S. Department of the Interior, Bureau of Mines, 1972.
40
MANUAL ON HYDROCARBON
ANALYSIS
[4 ] Csoklich, Ch., Ebner, B., and Schenz, R., "Modern Crude Oil Practices-Austria's OEMV," The Oil and Gas Journal, March 21, 1983, pp. 86-90. [5 ] O'Donnell, R. J., "Modern Crude Oil Practices--Standard Oil of California Companies," The Oil and Gas Journal, pp. 90-93. [6 ] McNelis, F. B., "Modern Crude Oil Practices--Exxon Organizations," The Oil and Gas Journal, pp. 94-97. [7 ] Wampler, R. J. and Kirk, E. L., "Modern Crude Oil Practices-Gulf Companies," The Oil and Gas Journal, pp. 98-104. [8 ] Nelson, G.V., Schierberg, G. R., and Sequeira, A., "Modern Crude Oil Practices--The Texaco System," The Oil and Gas Journal, pp. 108, 112, 116, 118-120. [9 ] McCleskey, G. and Joffe, B. L., "Modern Crude Oil Practices-Phillips Petroleum Co.," The Oil and Gas Journal, pp. 124, 126-127. [10] Aalund, L. R., "Guide to Export Crudes for the '80s--1 to 13," The Oil and Gas Journal, April 11, May 2, 23, June 6, 20, July 4, 25, Aug. 22, Sept. 5, Oct. 24, Nov. 7, 21, Dec. 12, 19, 1983. [11 ] O'Donnell, J., "Crude Oils," Criteria for Quality of Petroleum Products, J. P. Allison, Ed., John Wiley, New York, 1973, pp. 10-21. [12 ] Smith, N. A. C., Smith, H. M., Blade, O. C., and Garton, E. L., "The Bureau of Mines Routine Method for the Analysis of Crude Petroleum 1. The Analytical Method," Bulletin 490, U.S. Department of the Interior, Bureau of Mines, 1951. [13 ] Hydrogen Sulfide and Mercaptan Sulfur in Liquid Hydrocarbons by Potentiometric Titration, Method 163, UOP Laboratory Test Methods for Petroleum and Its Products, UOP Inc., Des Plaines, IL, 1989. [14 ] Impurities in Petroleum, Petrolite Corporation, Houston, 1958. [15 ] Watson, K. M., Nelson, E. F., and Murphy, G. B., "Characterization of Petroleum Fractions," Industrial and Engineering Chemistry, Vol. 27, 1935, pp. 1460-1464. [16 ] Calculation of UOP Characterization Factor and Estimation of Molecular Weight of Petroleum Oils, Method 375, UOP Laboratory Test Methods for Petroleum and Its Products, UOP Inc., Des Plaines, IL, 1986.
[17] Nelson, W. L., "Which Base of Crude Oil is Best?" The Oil and Gas Journal, Jan. 8, 1979, pp. 112-113. [18 ] Valkovi6, V., Trace Elements in Petroleum, The Petroleum Publishing Co., Tulsa, OK, 1978. [19 ] Yen, T. F., Ed., The Role of Trace Metals in Petroleum, Ann Arbor Science Publishers, Inc., Ann Arbor, MI, 1975. [20 ] Jones, M. C. K. and Hardy, R. L., "Petroleum Ash Components and Their Effect on Refractories," Industrial and Engineering Chemistry, Vol. 44, 1952, pp. 2615-2619. [21 ] Woodle, R. A. and Chandler, W. B., Jr., "Mechanisms of Occurrence of Metals in Petroleum Distillates," Industrial and Engineering Chemistry, Vol. 44, 1952, pp. 2591-2596. [22 ] Childs, W. V. and Vickery, E. H., "The Phillips Small Sample Octane Number Methods, Automation of a Knock-Test Engine," Symposium on Laboratory and Pilot Plant Automation, Washington, DC, August 28-September 2, 1983, American Chemical Society, Washington, DC, 1983, pp. 979-990. [23 ] Richter, F.P., Caesar, P.D., Meisel, S.L., and Offenhauer, R. D., "Distribution of Nitrogen in Petroleum According to Basicity," Industrial and Engineering Chemistry, Vol. 44, 1952, pp. 2601-2605. [24] Asphaltene Precipitation with Normal Heptane, IP 143/84, Standard Methods for Analysis and Testing of Petroleum and Related Products, Vol. 1, Institute of Petroleum, London, 1988. [25 ] Dyroff, George V., Ed., Manual on Significance of Tests for Petroleum Products, 6th ed., American Society for Testing and Materials, West Conshohocken, PA, 1993. [26 ] Aalund, L. R., "Guide to Export Crudes for the '80s-- 1," The Oil and Gas Journal, April 1, 1983, p. 71. [27 ] Villalanti, D. C., Janson, D., and Colle, P., "Hydrocarbon Characterization by High Temperature Simulated Distillation," Session 4, AIChE Spring Meeting, Houston, TX, March 19-23, 1995. [28 ] Application Note 9701, "Characterization of Vacuum Gas Oils by the AC Heavy Distillates Analyzer," AC--Analytical Controls Inc., Bensalem, PA.
7
Analysis of Aromatic Hydrocarbons by Charles H. Pfeiffer INTRODUCTION
Eventually all of the light aromatics obtainable from the coking operation were being used and shortages occurred. The world needed another source, and that source was petroleum. Even as early as the late 1920s, crude oil was evaluated as a source of light aromatics. Not until the late 1940s, however, did the development of catalytic reforming and liquidliquid extraction provide large quantities of aromatic hydrocarbons for use by the chemical industry and as a blending ingredient in high-octane gasoline.
THE HISTORYOF INDUSTRIALanalyses of aromatic hydrocarbons began in the 1920s when the production of benzene from coke by-products became commercially viable. By the 1930s, the rapid growth in demand for benzene as well as the commercial production of heavier aromatics led to the formulation of a considerable number of empirical analytical procedures. At this time, ASTM Committee D16 on Aromatic Hydrocarbons was formed. In the more than 50 years that this group has been active, the changes in analytical techniques have progressed hand-in-hand with the advancements in process technology and the expansion in the demand for high-purity aromatic products. As coal was heated in the absence of oxygen to produce coke, the lighter chemicals were vaporized and separated from the coal. Cooling the vapors condensed a highly aromatic liquid. Fractional distillation was used to separate the hydrocarbons into narrow-boiling fractions representing single aromatics, such as benzene, or groups of aromatics, such as xylenes. The contaminants were largely sulfur-, oxygen-, and nitrogen-containing hydrocarbons. Estimates of the purity of these products were determined in laboratories using procedures such as ASTM Test Methods D850, Distillation of Industrial Aromatic Hydrocarbons and Related Materials, 1 and D852, Solidification Point of Benzene. t Contaminants in the products caused corrosion and product degradation in the downstream units. The following ASTM Test Methods were developed to address these problems: ASTM Test Methods D853, Hydrogen Sulfide and Sulfur Dioxide Content (Qualitative) of Industrial Aromatic Hydrocarbons/ D848, Acid Wash Color of Industrial Aromatic H y d r o c a r b o n s / a n d D849, Copper Strip Corrosion of Industrial Aromatic Hydrocarbons. ~ As processes improved, aromatic hydrocarbons became available at substantially higher purities. The higher product purities opened up new industrial applications and required new standards. To make these materials easier to buy, sell, and trade, ASTM Test Methods D1015, Freezing Points of High-Purity Hydrocarbons,2 D 1016, Purity of Hydrocarbons from Freezing Points, 2 and D 1078, Distillation Range of Volatile Organic Liquids/ were published. Later, methods that gave more specific compositional information would supplant these empirical tests.
CURRENT PRACTICES Cyclohexane, made from benzene, is a chemical intermediate in the production of nylon. Polyester is made from p-xylene, which is extracted from mixed xylenes. Synthetic rubber is made from styrene, which is made from ethylbenzene. Resins are made from phenol, which is made from cumene. Each of these feedstocks and intermediates requires a specific purity level as well as limits on specific impurities and groups of impurities. ASTM test methods were developed and revised in ASTM Committee D16 as each of these needs were identified and as requirements for each of the materials changed. Gas chromatography (GC) has become a primary technique for determining hydrocarbon impurities in individual aromatic hydrocarbons and the composition of mixed aromatic hydrocarbons. Although a measure of purity by GC is often sufficient, GC is not capable of measuring absolute purity; not all possible impurities will pass through the GC column, and not all those that do will be measured by the detector. Absolute purity is best measured by distillation range or freeze or solidification points. Despite this caveat, GC is a standard, widely used technique and is the basis of many current ASTM Committee D16 test methods for aromatic hydrocarbons. Most of these methods, listed below, were written with, or converted to, fused silica capillary columns. D2306 D2360 D3054 D3760
1Appears in this publication.
D3797
2Annual Book of ASTM Standards, Vol. 05.01.
41
Cs Aromatic Hydrocarbon Analysis by Gas Chromatography ~ Trace Impurities in Monocyclic Aromatic Hydrocarbons by Gas Chromatography 1 Purity and Benzene Content of Cyclohexane by Gas Chromatography I Analysis of Isopropylbenzene (Cumene) by Gas Chromatography ~ Analysis of o-Xylene by Gas Chromatography ~
42
MANUAL ON HYDROCARBON ANALYSIS
D3798 D4492 D4534 D4735 D5060 D5135 D5713 D5917
D6144
Analysis of p-Xylene by Gas Chromatography ~ Analysis of Benzene by Gas Chromatography 1 Benzene Content of Cyclic Products by Gas Chromatography 1 Determination of Trace Thiophene in Refined Benzene by Gas Chromatography ~ Determining Impurities in High-Purity Ethylbenzene by Gas Chromatography ~ Analysis of Styrene by Capillary Gas Chromatography 1 Analysis of High Purity Benzene for Cyclohexane Feedstock by Capillary Gas Chromatography 1 Trace Impurities in Monocyclic Aromatic Hydrocarbons by Gas Chromatography and External Calibration 1 Analysis of AMS (a-Methylstyrene) by Gas Chromatography I
When classes of hydrocarbons, such as olefins, need to be measured, techniques such as bromine index are used. ASTM Test Method D1492, Bromine Index of Aromatic Hydrocarbons by Coulometric Titration/ continues as a useful method, but D1491, Bromine Index of Aromatic Hydrocarbons by Potentiometric Titration, 3 was withdrawn in 1985 because of health concerns regarding its use of carbon tetrachloride as a solvent. It was eventually replaced by D5776, Bromine Index of Aromatic Hydrocarbons by Electrometric Titration,~ which is based on D2710, Bromine Index of Petroleum Hydrocarbons by Electrometric Titration, ~but uses the less toxic 1-methyl-2-pyrrolidinone as a solvent. Impurities other than hydrocarbons are of concern in the petroleum industry. For example, many catalytic processes are sensitive to sulfur contaminants. Consequently, ASTM committees responded by developing a series of state-of-theart methods to determine trace concentrations of sulfur-containing compounds. These methods included ASTM Test Methods D 1685, Traces of Thiophene in Benzene by Spectrophotometry/D3961, Trace Quantities of Sulfur in Liquid Aromatic Hydrocarbons by Oxidative Microcoulometry, D4045, Sulfur in Petroleum Products by Hydrogenolysis and Rateometric Colorimetry, 1 and D4735, Trace Thiophene in Refined Benzene by Gas ChromatographyJ Chloride-containing impurities are determined by ASTM Test Methods D5194, Trace Chloride in Liquid Aromatic Hydrocarbons/ and D5808, Determining Organic Chloride in Aromatic Hydrocarbons and Related Chemicals by Microcoulometry. l Nitrogen-containing impurities are determined by ASTM Test Method D6069, Trace Nitrogen in Aromatic Hydrocarbons by Oxidative Combustion and Reduced Pressure Chemiluminescence DetectionJ Many of these test methods have sensitivity to 1 mg/kg, reflecting the needs of industry to determine very low levels of these contaminants. In addition to those tests previously mentioned, a number of other ASTM Test Methods are regularly used for the analysis of aromatics and are listed below: D847
Acidity of Benzene, Toluene, Xylenes, Solvent Naphthas, and Similar Industrial Aromatic Hydrocarbons 4
3Discontinued; see 1985 Annual Book of ASTM Standards, Vol. 06.03.
D1493 D1555 D1686
D2119 D2121 D2340 D2935 D3160 D3505 D3799 D4590
Solidification Point of Industrial Organic Chemicals 4 Calculation of Volume and Weight of Industrial Aromatic Hydrocarbons4 Color of Solid Aromatic Hydrocarbons and Related Materials in the Molten State (Platinum-Cobalt Scale) 4 Aldehydes in Styrene Monomer 4 Polymer Content of Styrene Monomer 4 Peroxides in Styrene Monomer 4 Apparent Density of Industrial Aromatic Hydrocarbons 4 Phenol Content of Cumene (Isopropylbenzene) or AMS (~-Methylstyrene) 4 Density or Relative Density of Pure Liquid Chemicals 4 Purity of Styrene by Freezing Point Method 4 Colorimetric Determination of p-tert-Butylcatechol in Styrene Monomer or AMS (a-Methylstyrene) by Spectrophotometry4
FUTURE TRENDS Timeliness of analyses and the amount of labor required to perform them continue to grow in importance. Although many laboratories have limits on staffing, they may still be able to make a one-time capital purchase of equipment to make the available staff more productive. Instrumental and automated methods are replacing chemical and physical methods in the laboratories, and ASTM is supporting this trend by writing test methods using contemporary technology and by listing these test methods in ASTM specifications. The ability of ASTM Committee D16 to write these methods in a timely manner has been made possible, in part, by increased vendor activity, a trend that is expected to continue. For relative density, most labs now use ASTM Test Method D4052, Density and Relative Density of Liquids by Digital Density Meter. 1 Distillation methods have been or are being rewritten to include automated distillation apparatus. For trace sulfur, D4045 has become the industry standard. Recently, this method has been optimized for aromatics analysis as ASTM Test Method D6212, Total Sulfur in Aromatic Compounds by Hydrogenolysis and Rateometric ColorimetryJ Development in D16.0E on a proposed method, "Total Sulfur in Aromatic Compounds by Oxyhydropyrolysis and Difference Photometry," is continuing, utilizing new equipment. Methods for trace sulfur and trace nitrogen by electrochemical detection have also been proposed. The classic platinum-cobalt color method, ASTM Test Method D1209, Color of Clear Liquids (Platinum-Cobalt Scale)/which requires subjective visual color comparison, is slowly being replaced by methods such as ASTM Test Method D5386, Color of Liquids Using Tristimulus Colorimetry.l This new standard is currently limited to a maximum color of 30 because, for higher color values, the vendors' algorithms to convert tristimulus values to Pt-Co color produce different results. Currently, three major instrument manufacturers are 4Annual Book of ASTM Standards, Vo]. 06.04.
CHAPTER 7 - - A N A L Y S I S OF AROMATIC HYDROCARBONS working together on a common algorithm, which may be published as an appendix to the standard. The labor requirements of GC methods are also being addressed. Traditionally, trace analyses by GC have been quantitated using an internal standard for calibration. These test methods require careful weighing procedures for each sample. Now, with the routine use of autosamplers to provide repeatable injections, an external standard procedure is preferred as a means of saving analyst time. Trace impurities by GC, ASTM Test Method D5917, was written as an equivalent to the internal standard GC method D2360. Because of continuing concerns over labor requirements, ASTM Committee D 16 is currently trying to eliminate redundant tests in Committee DI6 Specifications. For example, if a specification for high-purity benzene includes distillation range, purity by GC, and solidification point, a density or
43
relative density test is not justified. Similarly, current commercial high-purity aromatic hydrocarbons always pass acidity, copper corrosion, hydrogen sulfide, and sulfur dioxide tests, so the continuing need for these tests on a routine basis is being questioned. More stringent product requirements, advanced catalytic processing techniques, improved feedstock purification for specific downstream processes, and health and environmental requirements are driving the limits of impurities into the less than parts-per-million range. Efforts to provide quantitative analyses at this level continue. As raw material sources, product distributions, and methodologies change, efforts to publish methods based on current technology will continue to go hand-in-hand with these industrial technological changes.
Part 2--ASTM Test Methods The test m e t h o d s herein are a r r a n g e d in a l p h a n u m e r i c sequence. The page n u m b e r s a p p l y only to this m a n u a l a n d not to the s t a n d a r d d o c u m e n t s as they a p p e a r in the a n n u a l ASTM Book of Standards. See Table 2 in the front of this m a n u a l for a list of test m e t h o d s b y subject.
45
l]~ Designation:
D
5 - 95
Standard Test Method for Penetration of Bituminous Materials I This standard is issued under the fixed de~gnation D 5; the number immediately following the de~gnation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (E) indicates an editorial change since the last revision or reapproval.
This test method has been approved for use by agencies of the Department of Defense. Consult the DoD Index of Specifications and Standards for the specific year of issue which has been adopted by the Department of Defense.
1. Scope 1. I This test method covers determination of the penetration of semi-solid and solid bituminous materials. 1.2 The needles, containers and other conditions described in this test method provide for the determinations of penetrations up to 500. 1.3 The values stated in SI units are to be considered standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
5. Significance and Use 5.1 The penetration test is used as a measure of consistency. Higher values of penetration indicate softer consistency. 6. Apparatus 6.1 Penetration ApparatusDAny apparatus that permits the needle holder (spindle) to move vertically without measurable friction and is capable of indicating the depth of penetration to the nearest 0.1 ram, will be acceptable. The weight of the spindle shall be 47.5 + 0.05 g. The total weight of the needle and spindle assembly shall be 50.0 + 0.05 g. Weights of 50 + 0.05 g and 100 ± 0.05 g shall also be provided for total loads of I00 g and 200 g, as required for some conditions of the test.The surface on which the sample container rests shall be flatand the axis of the plunger shall be at approximately 90" to this surface. The spindle shall be easily detached for checking its weight. 6.2 Penetration Needle: 6.2.1 The needle (see Fig. 1) shall be made from fully hardened and tempered stainless steel, Grade 440-C or equal, HRC 54 to 60. The standard needle shall be approximately 50 mm (2 in.) in length, the long needle approximately 60 mm (24 in.). 6 The diameter of all needles shall be 1.00 to 1.02 mm (0.0394 to 0.0402 in.). It shall be symmetrically tapered at one end by grinding to a cone having an angle between 8.7 and 9.7" over the entire cone length. The cone should be coaxial with the straight body of the needle. The total axial variation of the intersection between the conical and straight surfaces shall not be in excess of 0.2 mm (0.008 in.). The truncated tip of the cone shall be within the diameter limits of 0.14 and 0.16 mm (0.0055 and 0.0063 in.) and square to the needle axis within 2". The entire edge of the truncated surface at the tip shall be sharp and free of burrs. When the surface texture is measured in accordance with American National Standard B46.1 the surface roughness height of the tapered cone shall be 0.2 to 0.3 ~tm (8 to 12 ~tin.) arithmetic average. The needle shall be mounted in a non-corroding metal ferrule. The ferrule shall be 3.2 ± 0.05 mm (0.12 ± 0.003 in.) in diameter and 38 ± 1 mm (1.50 ± 0.04 in.) in length. The exposed length of the standard nee~e shall be within the limits of 40 to 45 mm (1.57 to 1.77 in.), and the exposed length of the long needle shall be 50 to 55 mm (1.97 to 2.19 in.). The needle shall be rigidly mounted in the ferrule. The run-out (total-indicator reading) of the needle tip and any portion of the needle relative to the
2. Referenced Documents 2.1 A S T M Standards: C 670 Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials2 D 36 Test Method for Softening Point of Bitumen (Ringand-Ball Apparatus) 3 E 1 Specification for ASTM Thermometers4 E 77 Test Method for Inspection and Verification of Liquid-in-Glass Thermometers4 2.2 ANSI Standard? B 46.1 Surface Texture 3. Terminology 3.1 Definition: 3.1.1 penetration, n--consistency of a bituminous material expressed as the distance in tenths of a millimeter that a standard needle vertically penetrates a sample of the material under known conditions of loading, time, and temperature.
4. Summary of Test Method 4.1 The sample is melted and cooled under controlled conditions. The penetration is measured with a penetrometer by means of which a standard needle is applied to the sample under specificconditions. i This test method is under the jurisdiction of ASTM Committee D-4 on Road and Paving Materials and is the direct responsibility of Subcommittee 1304.44 on
Rheolngical Tests. Current edition approved Sept. 10, 1995. Published February 1996. Originally published as D 5 - 59 T. Last previous edition D 5 - 94. 2 Annual Book of ASTM Standards, Vol 04.02. 3 Annual Book of ASTM Standards, Vol 04.04. 4 Annual Book of ASTM Standards, Vol 14.03. 5 Available from American National Standards Institute, I I W. 42nd St., 13th Floor, New York, NY 10036.
e Long needles are available from Stanhope-Seta, Park Close, Englefleld Green, Eglmm, Surrey, U.K. TW20 OXD.
47
~ DS ,100 /o /02mm
e ......... FiG. 1
6.7 Thermometers--Calibrated liquid-in-glass thermometers of suitable range with subdivisions and maximum scale error of 0. I*C (0.2*F) or any other thermometric device of equal accuracy, precision and sensitivity shall be used. Thermometers shall conform to the requirements of Specification E 1. 6.7.1 Suitable thermometers commonly used are:
0./4/o 0./6 m m d~°4-O' to 9°dO '.- .
"'r approx. lL _1 as required----L~-J~--"-'-"-~--'~=~----"
Needle for Penetration Test
ferrule axis shall not exceed 1 mm (0.04 in.). The weight of the ferrule needle assembly shall be 2.50 _.+ 0.05 g. (A drill hole at the end of the ferrule or a fiat on the side is permissible to control the weight.) Individual identification markings shall be placed on the ferrule of each needle; the same markings shall not be repeated by a manufacturer within a 3-year period. 6.2.2 Needles used in testing materials for conformance to specifications shall be shown to have met the requirements of 6.2.1 when tested by a qualified agency. 6.3 Sample ContainerV--A metal or glass cylindrical, fiat-bottom container of essentially the following dimensions shall be used:
Range
17C or 17F
19 to 27*(2 (66 to 80°F)
63C or 63F 64(2 or 64F
- 8 to +32"(2 (18 to 89"F) 25 to 55"C (77 to 131"F')
6.7.2 The thermometer used for the water bath shall periodically be calibrated in accordance with Test Method E77.
7. Preparation of Test Specimen 7.1 Heat the sample with care, stirring when possible to prevent local overheating, until it has become sufficiently fluid to pour. In no ease should the temperature be raised to more than 60"C above the expected softening point for tar pitch in accordance with Test Method D 36, or to more than 90"C above it for petroleum asphalt (bitumen). Do not heat samples for more than 30 min. Avoid incorporating bubbles into the sample. 7.2 Pour the sample into the sample container to a depth such that, when cooled to the temperature of test, the depth of the sample is at least 10 mm greater than the depth to which the needle is expected to penetrate. Pour two separate portions for each variation in test conditions. 7.3 Loosely cover each container as a protection against dust (a convenient way of doing this is by covering with a lipped beaker) and allow to cool in air at a temperature between 15 and 30"C for 1 to 1.5 h for the small container and 1.5 to 2 h for the taller. Then place the two samples together with the transfer dish, if used, in the water bath maintained at the prescribed temperature of test. Allow the smaller container to remain for 1 to 1.5 h and the taller (6 oz) container to remain for 1.5 to 2 h.
For penetrations below 200:
Diameter, mm Internal depth, mm For penetrations between 200 and 350: Diameter, mm Internal depth, mm
ASTM Number
55 35 55 70
6.4 Water B a t h - - A bath having a capacity of at least 10 L and capable of maintaining a temperature of 25 + 0. I*C or any other temperature of test within 0. I*C. The bath shall have a perforated shelf supported in a position not less than 50 mm from the bottom and not less than 100 mm below the liquid level in the bath. If penetration tests are to be made in the bath itself, an additional shelf strong enough to support the penetrometer shall be provided. Brine may be used in the bath for determinations at low temperatures. NoTE l - - T h e use o f distilled water is recommended for the bath. Take care to avoid contamination o f the bath water by surface active agents, release agents, or other chemicals; as their presence may affect the penetration values obtained.
8. Test Conditions 8.1 Where the conditions of test are not specifically mentioned, the temperature, load, and time are understood to be 25"C (77"F), 100 g, and 5 s, respectively. Other conditions may be used for special testing, such as the following:
6.5 Transfer D i s h - - W h e n used, the transfer dish shall have a capacity of at least 350 mL and of sufficient depth of water to cover the large sample container. It shall be provided with some means for obtaining a firm bearing and preventing rocking of the container. A three-legged stand with three-point contact for the sample container is a convenient way of ensuring this. 6.6 Timing Device--For hand-operated-penetrometers any convenient timing device such as an electric timer, a stop watch, or other spring activated device may be used provided it is graduated in 0.1 s or less and is accurate to within +0.1 s for a 60-s interval. An audible seconds counter adjusted to provide 1 beat each 0.5 s may also be used. The time for a 1 l-count interval must be 5 + 0.1 s. Any automatic timing device attached to a penetrometer must be accurately calibrated to provide the desired test interval within +0.1 s.
Temperature, "C ('F) 0 (32) 4 (39.2) 45 (113) 46.1 (I 15)
Load, g
Time, s
200 200 50 50
60 60 5 5
In such cases the specific conditions of test shall be reported. 9. Procedure 9. I Examine the needle holder and guide to establish the absence of water and other extraneous materials. If the penetration is expected to exceed 350 use a long needle, otherwise use a short needle. Clean a penetration needle with toluene or other suitable solvent, dry with a clean cloth, and insert the needle into the penetrometer. Unless otherwise specified place the 50-g weight above the needle, making the total weight 100 + 0.1 g.
vSample Containers are available from Ellisco Inc., 6301 Eastern Ave., Baltimore MD, 21224 and Freund Can Co., 155 West 84th St., Chicago IL, 60620-1298.
48
(I~Ti~ D S TABLE 1
9.2 If tests are to be made with the penetrometer in the bath, place the sample container directly on the submerged stand of the penetrometer (Note 2). Keep the sample container completely covered with water in the bath. If the tests are to be made with the penetrometer outside the bath, place the sample container in the transfer dish, cover the container completely with water from the constant temperature bath and place the transfer dish on the stand of the penetrometer. NOTE 2--For referee tests, penetrationsat temperatures other than 25°C (77"F) should be made without removing the sample from the bath.
Matedal
Single-operator predsion: Asphalts at 77"F (25*(3) below 50 Asphalts at 77"F (25"C) 50 penetration lull above, percent of thelr mean Tar pltct~s at 770F (250C)A percent of thelr mean Asphalts at 770F (250C) below 50 penetration, units Asphalts at 770F (2SoC) 50 penetration and above, percent of thelr rnean Tar pitches at 770F (25*C),A units
49
149
249
500
2
4
12
20
1
1.1
3
5.2
15
1.4 2.8 1.4
precision at other temperatures is being determined. 11.1.1 Single Operator PrecisionmThe single operator coefficient of variation has been found to be 1.4 % for penetrations above 60, and the single operator standard deviation has been found to be 0.35 % for penetrations below 50. Therefore, the results of two properly conducted tests by the same operator on the same material of any penetration, using the same equipment, should not differ from each other by more than 4 % of their mean, or I unit, whichever is larger. 11.1.2 Multilaboratory Precision--The multilaboratory coefficient of variation has been found to be 3.8 % for penetrations above 60, and the multilaboratory standard deviation has been found to be 1.4 for penetrations below 50. Therefore, the results of two properly conducted tests on the same material of any penetration, in two different laboratories, should not differ from each other by more than 11% of their mean, or 4 units, whichever is larger.
10. Report 10.1 Report to nearest whole unit the average of three penetrations whose values do not differ by more than the following: Penetration Maximum difference between highest and lowest penetration
0.35
,~ ~ N of predsk~ for tar pltches are _~___,~'Jon results from 2 pitches with penetraUonof 7 and 24. Estimates may not be appUcal~ to apprec/ablyharder or softer matsdm.
9.4 Make at least three determinations at points on the surface of the sample not less than 10 mm from the side of the container and not less than 10 mm apart. If the transfer dish is used, return the sample and transfer dish to the constant temperature bath between determinations. Use a clean needle for each determination. If the penetration is greater than 200, use at least three needles leaving them in the sample until the three determinations have been completed.
250to
(d2s) or (d2s ~)
MulBaboratoryprec~¢~:
NOTE 3--The positioning of the needle can be materially aided by
150to
Acceptable Range of Two Test Results
penetration,units
using an illuminatedpoly-methylmethacrylatetube.
50to
Standard Deviation or Coefficient of Variation (Is) or
(is x)
9.3 Position the needle by slowly lowering it until its tip just makes contact with the surface of the sample. This is accomplished by bringing the actual needle tip into contact with its image reflected on the surface of the sample from a properly placed source of fight (Note 3). Either note the reading of the penetrometer dial or bring the pointer to zero. Quickly release the needle holder for the specified period of time and adjust the instrument to measure the distance penetrated in tenths of a millimetre. If the container moves, ignore the result.
0to
Precision Cr~llrli
NOTE 4---These values represent, respectively, the dls (or dls %) and
d2s (or d2s %) limits as d__~cri_ "bed in PracticeC 670. 11.1.3 Bias--This test method has no bias because the values determined arc defined only in terms of the test method.
11. Precision and Bias 11.1 Use the following criteria for judging the acceptability of penetration results for asphalt at 25"C. The
12. Keywords 12.1 asphalt; bitumen; penetration
The American Society for Testing and Materials takes no position respecting the vahdity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the vahdity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting ol the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Herbor Drive, West Conshohocken, PA 19428.
49
(~~ll~ Designation: D 36 - 95 Standard Test Method for Softening Point of Bitumen (Ring-and-Ball Apparatus) 1 This standard is issued under the fixed designation D 36; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
bitumens, as one element in establishing the uniformity of shipments or sources of supply, and is indicative of the tendency of the material to flow at elevated temperatures encountered in service.
1. Scope 1.1 This test method covers the determination of the softening point of bitumen in the range from 30 to 157"C (86 to 315"F) using the ring-and-ball apparatus immersed in distilled water (30 to 80"C), USP glycerin (above 80 to 157"C), or ethylene glycol (30 to 110*C). 1.2 The values stated in SI units are to be regarded as the standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
5. Apparatus 5.1 Rings--Two square-shouldered brass rings conforming to the dimensions shown in Fig. l(a). 5.2 Pouring Plate--A fiat, smooth, brass plate approximately 50 by 75 mm (2 by 3 in.). 5.3 Balls--Two steel balls, 9.5 mm (3/8 in.) in diameter, each having a mass of 3.50 _ 0.05 g. 5.4 Ball-Centering Guides--Two brass guides for centering the steel balls, one for each ring, conforming to the general shape and dimensions shown in Fig. 1 (b). 5.5 Bath--A glass vessel, capable of being heated, not less than 85 mm in inside diameter and not less than 120 mm in depth from the bottom of the flare.
2. Referenced Documents
2.1 ASTM Standards." C 670 Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials 2 D 92 Test Method for Flash and Fire Points by Cleveland Open Cup 3 D 140 Practice for Sampling Bituminous Materials4 D 3461 Test Method for Softening Point of Asphalt and Pitch (Mettler Cup-and-Ball Method) s E 1 Specification for ASTM Thermometers 6
NOTe I - - A n 800-mL, low-form Griffin beaker of heat-resistant glass meets this requirement.
5.6 Ring Holder and Assembly--A brass holder designed to support the two rings in a horizontal position, conforming to the shape and dimensions shown in Fig. 1 (c), supported in the assembly illustrated in Fig, 1 (d). The bottom of the shouldered rings in the ring holder shall be 25 mm (I.0 in.) above the upper surface of the bottom plate, and the lower surface of the bottom plate shall be 16 + 3 mm (% _+ I/s in.) from the bottom of the bath. 5.7 Thermometers: 5.7.1 An ASTM Low Softening Point Thermometer, having a range from - 2 to + 80"C or 30 to 180*F, and conforming to the requirements for Thermometer 15C or 15F as prescribed in Specification E 1. 5.7.2 An ASTM High Softening Point Thermometer, having a range from 30 to 200"C or 85 to 392"F, and conforming to the requirements for Thermometer 16C or 16F as prescribed in Specification E 1. 5.7.3 The appropriate thermometer shall be suspended in the assembly as shown in Fig. I (d) so that the bottom of the bulb is level with the bottom of the rings and within 13 mm (0.5 in.) of the rings, but not touching them or the ring holder. Substitution of other thermometers shall not be permittted.
3. Summary of Test Method 3.1 Two horizontal disks of bitumen, cast in shouldered brass rings, are heated at a controlled rate in a liquid bath while each supports a steel ball. The softening point is reported as the mean of the temperatures at which the two disks soften enough to allow each ball, enveloped in bitumen, to fall a distance of 25 mm (1.0 in.). 4. Significance and Use 4.1 Bitumens are viscoelastic materials without sharply defined melting points; they gradually become softer and less viscous as the temperature rises. For this reason, softening points must be determined by an arbitrary and closely defined method if results are to be reproducible. 4.2 The softening point is useful in the classification of This test method is under the jurisdhction of ASTM Committee D-8 on Roofing, Waterproofing, and Bituminous Materials and is the direct responsibdity of Subcommittee I:)08.03 on Surfacing and Bituminous Materials for Membrane Waterproofing and Builtup Roofing. Current edition approved Oct. 10, 1995. Published December 1995. Originally published as D 36 - 62T. Last previous edition D 36 - 86 (1993) ~j. 2 Annual Book ¢fASTM Standards, Vol 04.02. 3 Annual Book ¢fASTM Standards, Vol 05.01. 4 Annual Book of ASTM Standards, Vol 04.03. 5 Annual Book of ASTM Standards, Vol 04.04. 6 Annual Book of ASTM Standards, Vol 14.03.
6. Reagents and Materials 6.1 Bath Liquids: 6.1.1 Freshly Boiled Distilled Water. NOTE 2 - - T h e use o f freshly boiled distilled water is essential to avoid trapping air bubbles on the surface o f the specimen which m a y affect the
results.
50
I1~ D 36 I
Q
.. - "1 ZO~ ss
, / ~ slightly (opprox/motely O.OJ mmll /l. _.~ Iorger Ihon 9 ~ m m to o/Iowploc/n~:'~;-'~ ond centerin~ 9.5-ram steel boll.
Note: This diomefer to be
I---,.
--19.0- - ~
Th/s ring.
I
r/~
rtld
l.-- ..o--J Inside "D/ometer Full 23.0ram to slide over ring
"
vIA
'
"... -J
Note: diometer to be ~" full lg.0mm t o ~ r m # I n s e r t i o n ,, s of
-4 s.61,,
]0o
_L
(o) Shouldered Ring
¢~
iI i
q.
P,'-- 15.9- ~1
I.
, ,
i~qo. ~ ~,
.-Rounded lrillef • -z3.o
"%~
rid
(b) Boll Centering Guide
1/ '
rr a
(c) Ring Holder
(d) Two-Ring Assembly NOTE~AIIdimensionsare in millimetres. FIG. 1 Shouldered Ring, Bali-Centering Guide, Ring Holder, and Assembly of Apparatus Showing Two Rings 6.1.2
USPGlycerin,or
in other tests such as those for penetration and flash point.
NOTE 3--CAUTION:--Glycerin has a flash point of 160"C (320"F) in accordance with Test Method D 92.
7. Sampling
EthyleneGlycol,
7.1 Sample the material in accordance with Practice D 140.
6.1.3 with a boiling point between 195 and 197"C (383 and 387"F). NOTE 4--CAUTION:--Ethylene glycol is toxic when taken internally or inhaled as a vapor. Avoid prolonged or repeated skin contact and inhalation of vapors. Its flash point is 115°C (239°F) in accordance with Test Method D 92. When using this bath liquid, conduct the test in a vented laboratory hood with adequate exhaust fan capacity to ensure removal of toxic vapors.
8. Test
Specimens
8.1 Do not start unless it is planned to complete preparation and testing o f all asphalt specimens within 6 h and all coal-tar pitch specimens within 41/2 h. Heat the bitumen sample with care, stirring frequently to prevent local overheating, until it has become sufficiently fluid to pour (Note 6). Stir carefully to avoid incorporation of air bubbles in the sample.
ReleaseAgenls."
6.2 6.2.1 To prevent adhesion of bitumen to the pouring plate when casting disks, the surface of the brass pouring plate may be thinly coated just before use with silicone oil or grease (Note 5), a mixture o f glycerin and dextrin, talc, or china clay.
NOTE 6--An electric hot plate having a minimum power to unitsurface-area ratio of 37 k W / m 2 has been found satisfactory for this purpose.
NOTE 5--CAUTION:--Isolate silicones from other bituminous testing equipment and samples to avoid contamination, and wear disposable rubber gloves whenever handling silicones or apparatus coated with them. Silicone contamination can produce erroneous results
8. I. l Take no more than 2 h to heat an asphalt sample to its pouring temperature; in no case shall this be more than 110*C (200*F) above the expected softening point o f the asphalt. 51
~ 8.1.2 Take no more than 30 min to heat a coal-tar pitch sample to its pouring temperature; in no case shall this be more than 55"C (100*F) above the expected softening point of the coal-tar-pitch. 8.1.3 If the test must be repeated later, do not reheat this sample; use a fresh sample in a clean container to prepare new test specimens. 8.2 Heat the two brass rings (but not the pouring plate) to the approximate pouring temperature, and place them on the pouring plate treated with one of the release agents. 8.3 Pour a slight excess of the heated bitumen into each ring, and then allow the specimens to cool in ambient air for at least 30 min. For materials that are soft at room temperature, cool the specimens for at least 30 min at an air temperature at least 10*C (18*F) below the expected softening point. From the time the specimen disks are poured, no more than 240 min shall elapse before completion of the test. 8.4 When the specimens have cooled, cut away the excess bitumen cleanly with a slightly heated knife or spatula, so that each disk is flush and level with the top of its ring.
D 36 (_ 1.0*F). Reject any test in which the rate of temperature rise does not fall within these limits. NOTE 7--Rigid adherence to the prescribed heating rate is essential to reproducibility of results. Either a gas burner or electric heater may be used, but the latter must be of the low-lag, variable output type to maintain the prescribed rate of heating. 9.6 Record for each ring and ball the temperature indicated by the thermometer at the instant the bitumen surrounding the ball touches the bottom plate. Make no correction for the emergent stem of the thermometer. If the difference between the two temperatures exceeds I*C (2*F), repeat the test. 10. Calculation 10.1 For a given bitumen specimen, the softening point determined in a water bath will be lower than that determined in a glycerin bath. Since the softening point determination is necessarily arbitrary, this difference matters only for softening points slightly above 80"C (176*F). 10.2 The change from water to glycerin for softening points above 80"C creates a discontinuity. With rounding, the lowest possible asphalt softening point reported in glycerin is 84.5"C (184"F), and the lowest possible coal-tar pitch softening point reported in glycerin is 82.0"C (180*F). Softening points in glycerin lower than these translate to softening points in water of 80"C (176"F) or less, and shall be so reported. 10.2. l The correction for asphalt is -4.2"C (-7.6"F), and for coal-tar pitch is -1.7*C (-3.0*F). For referee purposes, repeat the test in a water bath. 10.2.2 Under any circumstances, if the mean of the two temperatures determined in glycerin is 80.0"C (176.0*F) or lower for asphalt, or 77.5"C (171.5*F) or lower for coal-tar pitch, repeat the test in a water bath. 10.3 To convert softening points slightly above 80"C (176"F) determined in water to those determined in glycerin, the correction for asphalt is +4.2"C (+7.6"F) and for coal-tar pitch is + 1.7*C (+3.0*F). For referee purposes, repeat the test in a glycerin bath. 10.3.1 Under any circumstances, if the mean of the two temperatures determined in water is 85.0"C (185.0"F) or higher, repeat the test in a glycerin bath. 10.4 Results obtained by using an ethylene glycol bath will vary from those using water and glycerin. The following formulas shall be used to calculate the differences:
9. Procedure 9.1 Select one of the following bath liquids and thermometers appropriate for the expected softening point: 9.1.1 Freshly boiled distilled water for softening points between 30 and 80"C (86 and 176"F); use Thermometer 15C or 15F. The starting bath temperature shall be 5 +I*C (41 + 2*F). 9.1.2 U S P glycerin for softening points above 80"C (176"F) and up to 157"C (315"F); use Thermometer 16C or 16F. The starting bath temperature shall be 30 + I*C (86 ± 2*F). 9.1.3 Ethylene glycol for softening points between 30 and 110°C (86 and 230°F); use Thermometer 16C or 16F. The starting bath temperature shall be 5 ± I°C (41 ± 2*F). 9.1.4 For referee purposes, all softening points up to 80*C (176°F) shall be determined in a water bath and all softening points above 80°C (176°F) shall be determined in a glycerin bath. 9.2 Assemble the apparatus in the laboratory hood with the specimen rings, ball-centering guides, and thermometer in position, and fill the bath so that the liquid depth will be 105 ± 3 mm (4'/8,± '/s in.) with the apparatus in place. If using ethylene glycol, make sure the hood exhaust fan is turned on and operating properly to remove toxic vapors. Using forceps, place the two steel balls in the bottom of the bath so they will reach the same starting temperature as the rest of the assembly. 9.3 Place the bath in ice water, if necessary, or gently heat to establish and maintain the proper starting bath temperature for 15 min with the apparatus in place. Take care not to contaminate the bath liquid. 9.4 Again using forceps, place a ball from the bottom of the bath in each ball-centering guide. 9.5 Heat the bath from below so that the temperature indicated by the thermometer rises at a uniform rate of 5"C (9*F)/min (Note 7). Protect the bath from drafts, using shields if necessary. Do not average the rate of temperature rise over the test period. The maximum permissible variation for any l-rain period after the first 3 rain shall be ± 0.5"C
Asphalt: SP (glycerin) -- 1.026583 × SP (ethylene glycol) - 1.334968°C SP (water) = 0.974118 x SP (ethylene glycol) - 1.44459°C
Coal Tar." SP (glycerin) = 1.044795 x SP (ethylene glycol) - 5.063574°C fSP (water) = 1.061111 x SP (ethylene glycol) - 8.413488°C 11. Report 11.1 When using ASTM Thermometer 15C or 15F, report to the nearest 0.2"C or 0.5*F the mean or corrected mean of the temperatures recorded in 9.6 as the softening point. ? Editoriallycorrected. 52
o a6 same sample of bitumen from two laboratories should not differ by more than 2.0"C (3.5"17).7 12.2 With ethylene glycol, the following criteria shall be used for judging the acceptability of results: 12.2. l Single-Operator Precision--The single-operator standard deviation has been found to be 0.72"C (1.29"F). Therefore, results of two properly conducted tests by the same operator on the same sample of bitumen should not differ by more than 2.0"C (3.5"F). 7 12.2.2 Multilaboratory Precision--The multilaboratory standard deviation has been found to be 1.08*C (1.95"F). Therefore, results of two properly conducted tests on the same sample of bitumen from two laboratories should not differ by more than 3.0"C (5.5"F). 7 12.3 BiasmThe procedure in Test Method D 36 has no bias because the value of the softening point of the bitumen test is defined in terms of this test method.
11.2 When using ASTM Thermometer 16C or 16F report to the nearest 0.5"C or 1.0*F the mean or corrected mean of the temperatures recorded in 9.6 as the softening point. 11.3 Report the bath liquid used in the test. 12. Precision and Bias 12.1 With distilled water or USP glycerin, the following criteria shall be used for judging the acceptability of results (95 % probability): 12.1.1 Single-Operator Precision--The single-operator standard deviation has been found to be 0.41°C (0.73°F). Therefore, results of two properly conducted tests by the same operator on the same sample of bitumen should not differ by more than 1.2°C (2.0°F). 7 12.1.2 Multilaboratory Precision--The multilaboratory standard deviation has been found to be 0.70°C (1.26°F). Therefore, results of two properly conducted tests on the
13. Keywords 13.1 asphalt; ball and ring; bitumen; coal tar; softening point
These numbers represent, respectively, the (IS) and (D2S) limits as described in Practice C 670.
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connechon with any item mentioned in this standard. Users o! this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn, Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meebng of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohocken, PA 19428.
53
( ~ , ) Designation:D 56 - 97a Standard Test Method for Flash Point by Tag Closed Tester 1 This standard is issued under the fixed designation D 56; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last renpproval. A superscript epsilon (e) indicates an editorial f~han~since the last revision or reapprovai.
This test method ha~ been approvedfor use by agencies of the Department of Defense. Consult the DoD Index of SpecOqcations and Standards for the specific year of issue which has been adopted by the Department of Defense. This test method has been adoptedfor use by gowrnment agencies to replaceMethod 1101 of Federal Test Method Standard No. 791b, and Method 4291 of Federal Test Method Standard No. 141A. INTRODUCTION
To ensure an acceptable precision, this dynamic flash point test employs a prescribed rate o f temperature rise for the material under test. The rate of heating may not in all cases give the precision quoted in the test method because of the low thermal conductivity o f certain materials. To improve the prediction of flammability, Test Method D 3941, which utiliT~s a slower heating rate, was developed. Test Method D 3941 provides conditions closer to equilibrium where the vapor above the liquid and the liquid are at about the same temperature. If a specification requires Test Method D 56, do not change to D 3941 or other test method without permission from the specifier. 1. Scope 1.1 This test method covers the determination of the Flash Point, by Tag manual and automated closed testers, of liquids with a viscosity below 5.5 mm2/s (cSt) at 40°C (104°F), or below 9.5 mm2/s (cSt) at 25"C (77°F), and a flash point below 93°C (200"F). 1.1.1 For the closed-cup flash point of liquids with the following properties: a viscosity of 5.5 mm2/s (cSt) or more at 40°C (104"1=); a viscosity o f 9.5 mm2/s (cSt) or more at 25°C (77°F); a flash point o f 93°C (200°F) or higher; a tendency to form a surface film under test conditions; or containing suspended solids, Test Method D 93 can be used. 1.1.2 For cut-back asphalts refer to Test Methods D 1310 and D 3143.
and cannot be used to describe or appraise the fire hazard or fire risk o f materials, products, or assemblies under actual fire conditions. However, results of this test can be used as elements of fire risk assessment which takes into account all of the factors which are pertinent to an assessment of the fire hazard of a particular end use. 1.3 Related Standards are Test Methods D 93, D 1310, D 3828, D 3278, and D 3941. 1.4 The values stated in SI units are to be regarded as standard. The values in parentheses are for information only. 1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific
NOTE l--The U.S. Department of Transportation (RSTA)2 and U.S. Department of Labor (OSHA) have established that liquids with a flash point under 37.8"C (100"F) are flammable as determined by this test method for those liquids which have a viscosityless than 5.5 mm2/s (cSt) at 40"C (104"F) or 9.5 mm2/s (cSt) or less at 25"C (77°F), or do not contain suspended solids or do not have a tendency to form a surface film while under test. Other flash point classifications have been established by these departments for liquids using this test.
hazard statements see Note 4 and refer to Material Data Sheets.
Safety
2. R e f e r e n c e d D o c u m e n t s
2.1 A S T M Standards: D93 Test Methods for Flash Point by Pensky-Martens Closed Cup Tester3 D 850 Test Method for Distillation of Industrial Aromatic Hydrocarbons and Related Materials4 D 1015 Test Method for Freezing Points of High-Purity Hydrocarbons3 D 1078 Test Method for Distillation Range of Volatile Organic Liquids4 D 1310 Test Method for Flash Point and Fire Points of Liquids by Tag Open-Cup Apparatus 5
1.2 This standard can be used to measure and describe the properties o f materials, products, or assemblies in response to heat and flame under controlled laboratory conditions i This test method is under the joint jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommince 1302.08 on Volatility. Current edition approved May 10, 1997 and July 10, 1997. Published October 1997. Originally published as D 56 - 18 T. Last previous edition D 56 - 96. 2 For information on United States Department of Transportation regulations, see Codes of United States Regulation 49 CFR Chapter ! and for information on United States Department of Labor regulations, see Code of United States Regulation 29 CFR Chapter XVIL Each of these items are revised annually and may be procured from the Superintendent of Documents, Government Printing Office, Washington, DC 20402.
s Annual Book of ASTM Standards, Vol 05.01. 4 Annual Book of ASTM Standards, Vo106.04. s Annual Book of ASTM Standards, Vo106.01.
54
~[~ D 5e D 3143 Test Method for Flash Point of Cutback Asphalt with Tag Open-Cup Apparatus 6 D 3278 Test Methods for Flash Point of Liquids by Small Scale Closed Cup Apparatus 5 D3798 Test Method for Analysis of p-Xylene by Gas Chromatography 4 D3828 Test Methods for Flash Point by Small Scale Closed Tester7 D3941 Test Method for Flash Point by the Equilibrium Method with a Closed-Cup Apparatus s D4057 Practice for Manual Sampling for Petroleum and Petroleum Products 7 E 1 Specification for ASTM Thermometers s 2.2 Federal Test Method Standards: Method 1101, Federal Test Method Standard No. 791b 9 Method 4291, Federal Test Method Standard No. 141A9 2.3 ISO Standards: ° Guide 34 Quality Systems Guidelines for the Production of Reference Materials Guide 35 Certification of Reference Materials--General and Statistical Principles
4. Summary of Test Method 4.1 The specimen is placed in the cup of the tester and, with the lid closed, heated at a slow constant rate. An ignition source is directed into the cup at regular intervals. The flash point is taken as the lowest temperature at which application of the ignition source causes the vapor above the specimen to ignite. 5. Significance and Use 5.1 Flash point measures the tendency of the specimen to form a flammable mixture with air under controlled laboratory conditions. It is only one of a number of properties that must be considered in assessing the overall flammability ha,nrd of a material. 5.2 Flash point is used in shipping and safety regulations to define flammable and combustible materials. One should consult the particular regulation involved for precise definitions of these classes. 5.3 Flash point can indicate the possible presence of highly volatile and flammable materials in a relatively nonvolatile or nonflammable material. For example, an abnormally low flash point on a sample of kerosene can indicate gasoline contamination.
3. Terminology 3.1 Definition: 3.1.1 flash point--the lowest temperature corrected to a pressure of 101.3 kPa (760 mm Hg) at which application of an ignition source causes the vapors of a specimen of the sample to ignite under specified conditions of test. 3.1.1.1 Discussion--The specimen is deemed to have flashed when a flame appears and instantaneously propagates itself over the entire surface of the fluid. 3.1.1.2 Discussion--When the ignition source is a test flame, the application of the test flame may cause a blue halo or an enlarged flame prior to the actual flash point. This is not a flash and should be ignored. 3.2 Definitions of Terms Specific to This Standard: 3.2.1 dynamic (non-equilibrium)--in this type of flash point apparatus, the condition of the vapor above the specimen and the specimen are not at the same temperature at the time that the ignition source is applied. 3.2.1.1 Discussion--This is primarily caused by the heating of the specimen at the constant prescribed rate with the vapor temperature ]a~,~rtg behind the specimen temperature. The resultant flash point temperature is generally within the reproducibility of the method. 3.2.2 equilibrium--in that type of flash point apparatus or test method, the vapor above the specimen and the specimen are at the ~ m e temperature at the time the ignition source is applied. 3.2.2.1 Discussion--This condition may not be fully achieved in practice, since the temperature is not uniform throughout the specimen and the test cover and shutter is generally cooler.
6. Sampling 6.1 Erroneously high flash points will be obtained when precautions are not taken to avoid the loss of volatile material. Containers should not be opened unnecessarily, to prevent loss of volatile material and possible introduction of moisture. Transfers should not be made unless the sample temperature is at least 10"C (18"F) below the expected flash point. When possible, flash point must be the first test performed on a sample and the sample must be stored at low temperature. 6.2 Samples are not to be stored in plastic (polyethylene, polypropylene, etc.) bottles, since volatile materials may diffuse through the walls of the bottle. Samples in leaky containers are suspect and not a source of valid results and shall be discarded in accordance with local regulations for flammable materials. 6.3 At least 50 mL of sample is required for each test. Refer to sampling Practice D 4057.
7. Apparatus (Manual Instrument) 7.I Tag Closed Tester--The apparatus is shown in Fig. I and described in detailin Annex A I. 7.2 Shield--A shield460 m m (18 in.)square and 610 m m (24 in.)high, open in front,is recommended. 7.3 Thermometers--For the test cup thermometer, use one as prescribed in Table 1. For the bath thermometer, any convenient type that has an adequately open scale covering the required range may be used; it is often convenient to use the same type of thermometer as used in the test cup. NOTE 2--Whenever thermomete~ complying with ASTM require. ments ate not available, thermometers complying with the requirements for The Institute of Petroleum thermometer IP 15C PM-Low can be
used.
e Annua/Book ofASTM .,~nnd~'ds, Vol 04.03. ' Annua/Book o f A S T M , S ~ , Vo105.02. s Annua/Book ¢fASTM,S~andards, Vol 14.03. 9 Available from Supez~tendent of Document& U.S. Government Printing Office, Wmlfington, DC 20402. ,o Available from American National Standard11n~itute, II W. 42nd St., 13th Floor, New York, NY 10036.
8. Preparation of Apparatus (Manual) 8.1 Support the tester on a level steady table. Unless tests are made in a draft-free room or compartment, surround the tester on three sides by the shield for protection from drafts. 55
(~
D 56 by carefully lubricating the slide shutter with high-vacuum silicone lubricant.
Both Thermometer
Cup Thermometer
8.4 Verify the performance of the manual apparatus at least once per year by determining the flash point of a certified reference material (CRM), such as those listed in Annex A2, which is reasonably close to the expected temperature range of the samples to be tested. The material shall be tested according to the procedure of this test method and the observed flash point obtained in 9.5 shall be corrected for barometric pressure (see Section 13). The flash point obtained shall be within the limits stated in Table A2.1 for the identified CRM or within the limits calculated for an unlisted CRM (see Annex A.2). 8.5 Once the performance of the apparatus has been verified, the flash point of secondary working standards (SWSs) can be determined along with their control limits. These secondary materials can then be utilized for more frequent performance checks (see Annex A2). 8.6 When the flash point obtained is not within the limits stated in 8.4 or 8.5, check the condition and operation of the apparatus to ensure conformity with the details listed in Annex A1, especially with regard to tightness of the lid (A1.1.2), the action of the shutter, the position of the ignition source (AI. 1.2.3), and the angle and position of the temperature measuring device (A1.1.2.4). After any adjustment, repeat the test in 8.4 or 8.5 using fresh test specimen, with special attention to the procedural details prescribed in the test method.
\
Flame Size Bead
FlameTip / O=1 Chamber
Test Cup
Both
Bath Stand for Gas Burner
I~
9. Procedure (Manual) 9.1 Using a graduated cylinder and taking care to avoid wetting the cup above the final fiquid level, measure 50 :t: 0.5 mL of the sample into the cup, both the sample and graduated cylinder being precooled, when necessary, so that the specimen temperature at the time of measurement will be 27 + 5"C (80 + 10"F) or at least 10"C (18°F) below the expected flash point, whichever is lower. It is essential that the sample temperature be maintained at least 10"C (18°F) below the expected flash point during the transfers from the sample container to the cylinder and from the cylinder to the test cup. Destroy air bubbles on the surface of the specimens by use of knife point or other suitable device. Wipe the inside of the cover with a clean cloth or absorbent tissue paper; then attach the cover, with the thermometer in place, to the bath collar. 9.2 Light the test flame, when used, adjusting it to the size of the small bead on the cover. Operate the mechanism on the cover in such a manner as to introduce the ignition source into the vapor space of the cup, and immediately bring it up again. The time consumed for the full operation should be 1 s, allowing equal time periods for the introduction and return. Avoid any hesitation in the operation of depressing and raising the ignition source. When a flash is observed on the initial operation of the mechanism, discontinue the test and discard the result. In this case, a fresh sample shall be cooled an additional 10°C (18"F), below the original specimen installation temperature. 9.2.1 Care must be exercised when using a test flame, if the flame is extinguished it cannot ignite the specimen and the gas entering the vapor space can influence the result. When the flame is prematurely extinguished the test must be
Gas Burner
,
RG. 1 Tag ClosedFluh Tester(Ihnuell Tests are not to be made in a laboratory draft hood or near ventilators. 8.2 Natural gas and bottled gas flame and electric ignitors have been found acceptable for use as the ignition source. NOTE 3: Warning--Gas pressure should not be allowed to exceed 300 mm (11.8 in.) of water pressure. 8.3 For flash points below 13°C (55°F) or above 60"(3 (140°F), use as a bath liquid a 1+ 1 mixture of water and ethylene glycol (see Warning--Note 4). For flash points between 130C (55"F) and 600C (1400F), either water or a water-glycol mixture can be used as bath liquid. The temperature of the liquid in the bath shall be at least 10"C (18"F) below the expected flash point at the time of introduction of the sample into the test cup. Do not cool bath liquid by direct contact with dry ice (solid carbon dioxide). NOTe 4: Warning--EthyleneGlycol--Poison. Harmful or fatal if swallowed.Vapor harmful.Avoidcontactwith skin. NOTI~5--Due to possible difficultyin maintainingthe prescribed rate of temperatureriseand due to the formationof ice offthe lid, results by this methodfor sampleshavingflashpointsbelow0"C (32"F)may be unreliable. Trouble due to ice formationon the slidecan be minimized 56
~[~ D 56 discontinued and any result discarded. 9.3 Flash Points Below 60"C (140°F)--When the flash point of the sample is known to be below 60°C (140"F), apply and adjust the heat so that the temperature of the portion will rise at a rate of I°C (2°F)/min :1:6 s. When the temperature of the specimen in the test cup is 5°C (10"F) below its expected flash point, apply the ignition source in the manner just described in 9.2 and repeat the application of the ignition source after each 0.5°C (1 °F) rise in temperature of the specimen. 9.4 Flash Points at 60°C (140°F) or Above--If the flash point of the sample is known to be 60°C (140°F) or higher, apply and adjust the heat so that the temperature of the specimen will rise at a rate of 3°C (5°F)/min + 6 s. When the temperature of the specimen in the test cup is 5°C (10°F) below its expected flash point, apply the ignition source in the manner just described in 9.2 and repeat the application of the ignition source each l°C (2"F) rise in temperature of the specimen. 9.5 When the application of the ignition source causes a distinct flash in the interior of the cup, as defined in 3.1.1, observe and record the temperature of the specimen as the flash point. Do not confuse the true flash with the bluish halo which sometimes surrounds the ignition source during applications immediately preceding the actual flash. 9.6 Discontinue the test and remove the source of heat. the lid and wipe the thermometer bulb. Remove the test cup, empty, and wipe dry. 9.7 If, at any time between the firstintroduction of the ignition source and the observation of the flashpoint, the rise in temperature of the specimen is not within the specified rate, discontinue the test, discard the result and repeat the test,adjusting the source of heat to secure the proper rate of temperature rise,or using a modified "expected flash point," or both, as required. 9.8 Never make a repeat test on the same specimen of sample; always take fresh specimen of sample for each test.
TABLE 1
11mnnometem
For tests
Below 4=C (40°F)
Use ASTM 11'wacme~ '~
570 or (571=)
At 4 to 49°0 (40 to 120°F) 9(3 o¢ (gF) 57C or (57F)
A Gomplom ~,,;_~:~ueatiol~for these them~motem are ~
Above 49°C (120°F) 9(3 or (91=) In ~
El.
a certified reference material (CRM) such as those listed in Annex A2, which is reasonably close to the expected temperature range of the samples to be tested. The material shall be tested according to the procedure of this test method and the observed flash point obtained in 9.5 shall be corrected for barometric pressure (see Section 13). The flash point obtained shall be within the limits stated in Table A2.1 for the identified CRM or within the limits calculated for an unlisted CRM (see Annex A2.) I 1.2.4 Once the performance of the apparatus has been verified, the flash point of secondary working standards (SWSs) can be determined along with their control limits. These secondary materials can then be utilized for more frequent performance checks (see Annex A2). 11.2.5 When the flash point obtained is not within the limits stated in 11.2.3 or 11.2.4, check the condition and operation of the apparatus to ensure conformity with the details listed in Annex AI, especially with regard to tightness of the lid (Al.l.2), the action of the shutter, the position of the ignition source (Al.l.2.3), and the angle and position of the temperature measuring device (AI.I.2.4). After any adju,mnent, repeat the test in I 1.2.3 or 11.2.4 using fresh test specimen, with special attention to the procedural derails prescribed in the test method.
12. Procedure (Automated) 12.1 Adjust the external cooling system, if required, to a temperature necessary to cool the heating area 10"C below the expected flash point. 12.2 Place the test cup in position in the instrument. 12.3 When using a gas test flame, light the pilot flame and the test flame and adjust the test flame to 4 m m (5/32 in.) in diameter. If the instrument is equipped with an electrical ignition device, adjust according to the manufacturer's instructions. 12.4 Enter the Expected Flash Point; this will allow the heating area to be cooled to the required minimum starting temperature. NOTe 6---Toavoidan abnormal heating rate when the specimenis at a low temperature, it is recommendedto precoolthe test cup and cover. This may be accomplished by placing the assemblyinto position in the instrument while it is cooling to 10"C (18*F) below the programmed Expected ~ Point.
10. Apparatus (Automated Instrument) 10.1 An automated flash point instrument is used that is capable of performing the test in accordance with Section 9, Procedure (Manual) of the test method. The apparatus can use a gas test flame or electric ignitor. The dimensions for the test cup and test cover are shown in Figs. A 1.1 and A 1.2. 10.2 Samples with low flash point may require a source of cooling for the heating area. 11. Preparation of Apparatus (Automted Instrument) 11.1 Support the tester on a level, steady table. Unless tests are made in a draR-free compartment, it is a good practice, but not required, to surround the tester with a shield to prevent draft. 11.2 The user of the automatic instrument must be sure that all of the manufacturer's instructions for calibrating, checking, and operating the equipment are followed. 11.2.1 Adjust the detection system per manufacturer's instructions. 11.2.2 Calibrate the temperature measuring device per manufacturer's instructions. 11.2.3 Verify the performance of the automated apparatus at least once per year by determining the flash point of
NOTe 7--Flash Point results determined in an "unknown Expected Flash Point mode" should be considered approximate. This value can be
used as the ExpectedHash Point when a fresh specimen is tested in the standard mode of operation. 12.5 Using a graduated cylinder and taking care to avoid wetting the cup above the final liquid level, measure 50 + 0.5 mL of the sample into the cup, both the sample and the graduated cylinder being precooled, when necessary, so that the specimen temperature at the time of the measurement is 27 + 5"C (80 + 10"F) or at least 10"C (18"F) below the expected flash point, whichever is lower. It is essential that the sample temperature be maintained at least 10°C (18°F) 57
~
D 56
below the expected flash point during the transfers from the sample container to the cylinder and from the cylinder to the test cup. Destroy air bubbles on the surface of the specimen by use of knife point or other suitable device. Wipe the inside of the cover with a clean cloth or absorbent tissue paper; then attach the cover, with the temperature measuring device in place, to the bath collar. Connect the shutter and ignition source activator, if so equipped, into the lid housing. Readjust the size of the test flame or the setting of the electrical ignition device. Test the ignition source dipping action, if so equipped, and observe if the apparatus functions correctly. Press the start key. If a flash is observed upon initial operation, discontinue the test and discard the result. In this case a fresh specimen shall be cooled to an additional 10*C (18"17)below the original specimen installation temperature.
weather stations and airports, are precorrected to give sea level readings; these must not be used. 13.3 Report the corrected flash point to the nearest 0.5°C (or I°F). 14. Precision and Bias 14.1 Precision--The following criteria shall be used for judging the aceeptabifity of results (95 % probability): 14.1.1 Repeatability---The difference between successive test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test material, would in the long run, in the normal and correct operation of the test method, exceed the following values only in one case in twenty: Flash Point,"(2('F) Rentability, "(2('F) Below 60"C(I40"F) 1.2"(2(2.0"F) At and Above60"C(138.2"F) 1.6"(2(3.0"F)
NOTE S---Careshould be taken when cleaning and positioning the lid assembly so not to damage or dislocate the flash detection system or temperature measuring device. See manufacturer's instructions for proper care and maintenance.
14.1.2 Reproducibility---The difference between two single and independent results, obtained by different operators working in different laboratories on identical test material, would in the long run, in the normal and correct operation of the test method, exceed the following values only in one case in twenty: Flash Point,"(2('F) Reproducibility,"12CF) Below60"(2(140"F) 4.YC (8"F) At and Above60"C(138.2"F) 5.8"(2(10"F) 14.2 Bias--The procedure in Test Method D 56 for measuring flash point has no bias since the Tag Flash Point can be defined only in terms of this test method. The current interlaboratory tests confirm that there is no relative bias between manual and automated procedures. In any case of dispute the flash point as determined by the manual procedure shall be considered the referee test. NOTE 9--Mixtures such as, but not limited, to those that are chlorinated or include water may cause there to be significantdifferences in the results obtained by manual and automatic instruments. For these mixtures, the precision statement may not apply. NoTE 10---The precision data were developed in a 1991 cooperative test programII using eight (8) samples. Twelve (12) laboratories participated with the manual apparatus and seventeen (17) laboratories participated with the automatic equipment. Information on the type of samples and their averageflashpointsare in the research report available at ASTM Headquarters.
12.6 The apparatus shall automatically control the test procedure as described in this test method. When the flash point is detected, the apparatus will record the temperature and automatically discontinue the test. If a flash is detected on the first application, the test should be discontinued, the result must be discarded and the test repeated with a fresh specimen. 12.7 When the apparatus has cooled down to a safe handling temperature (less than 55*(2 (130°F)) remove the cover and the test cup and clean the apparatus as recommended by the manufacturer. 13. Report 13.1 Correction for barometric pressure. Observe and record the ambient barometric pressure at the time and place of the test. When the pressure differs from 101.3 kPa (760 mm Hg), correct the flash point as follows: (1) Corrected flash point ffi C + 0.25 (101.3 - p) (2) Corrected flash point = F + 0.06 (760 - P) (3) Corrected flash point ffi C + 0.033 (760 - P) where: C ffi observed flash point, *C, F ffi observed flash point, *F, p = ambient barometric pressure, kPa, and P = ambient barometric pressure, m m Hg. 13.2 The barometric pressure used in this calculation must be the ambient pressure for the laboratory at the time of test. Many aneroid barometers, such as those used at
15. Keywords 15.1 combustible; fire risk; flammable; flash point; tag closed cup it Data is availablefromASTMHe~_dquarter~RequestRR:D02-1350.
58
~
D 56
ANNEXES (Mandatory Information) A1. APPARATUS AI.I The Tag closed tester shall consist of the test cup, lid with ignition source, and liquid bath conforming to the following requirements: A I.I.I Test Cup, of brass or other nonrusting metal of equivalent heat conductivity, conforming to dimensional requirements prescribed in Fig. AI.1. It shall weigh 68 + 1 g` AI.I.2 Lid: Al.l.2.1 The lid comprises a circle of nonmsting metal with a rim projecting downward about 15.9 mm (% in.), a slide shutter, a device which simultaneously opens the shutter and depresses the ignition source, and a slanting collar in which the cup-thermometer ferrule is inserted. Figure A 1.2 gives a diagram of the upper surface of the lid, showing dimensions and positions of the three holes opened and closed by the shutter, and the size and position of the opening for the cup thermometer. A1.1.2.2 The rim shall fit the collar of the liquid bath with a clearance not exceeding 0.4 mm (0.002 in.) and shah be slotted in such a manner as to press the lid firmly down on the top of the cup when the latter is in place in the bath. When this requirement is not met, the vertical position of the cup in the bath shall be suitably adjusted, as by placing a thin ring of metal under the flange of the cup. A1.1.2.3 The shutter shall be o~such size and shape that it covers the three openings in the lid when in the closed position and uncovers them completely when in the open position. The nozzle of the flame-exposure device, when
used, shall conform to the dimensions given in Table A I. I. The ignition source device shall be designed and constructed so that opening the shutter depresses the tip to a point approximately 2 mm (0.08 in.) to the right of the horizontal center of the middle opening of the lid (refer to lower part of Fig. AI.3). This will bring the ignition source to the approximate center of the opening` The plane of the underside of the lid shall be between the t o p and bottom of the t i p of the ignition source when the latter is fully depressed. A 1.1.2.4 The collar for the cup-thermometer ferrule shall be set at an angle which permits placement of the thermometer with its bulb approximately in the horizontal center of the cup, at a depth prescribed in Table A 1. I. Al.l.3 Liquid Bath, conforming to the limiting or minimum dimension shown in Fig. AI.3. It shall be of brass, copper, or other noncorroding metal of substantial construction. Sheet metal of about No. 20 B&S gage (0.812 ram) is satisfactory. It may, ff desired, be lagged with heat-insulating material to facilitate control of temperature. A I.I.4 Heater, of any type (electric, gas, alcohol, etc.) capable of controlling temperature as required in Section 9. An external electric heater, controlled by a variable voltage transformer, is recommended, AI.1.5 Bath Stand--For electric heating, any type of stand may be used. For alcohol lamp or gas burner, a stand, as illustrated in Fig` 1, to protect the ignition source from air currents (unless tests can be made in a draft-free room) is required.
~: 2.0 "=~----" 6 3 . 5 - - - - - ~
TABLE A1,1
Dimensional Requirements
Depth of I~Ul k~d surfacebelowtop of test cup
+o.Ts "---54.0
Depth of satn~e surface below top of test cup .J
Depth of bottom of bulb of test thermometerbelow
±0.5
top of cup when in place Insicle diameter of test cup
~'0.90 ~1.0
Diameter ol beacl on top of cover
+7,s
54.5
Diameter of opermg in tip of test flame nozzle
1
Outstcle diameter of tlp of test flame nozzle FIG. A1.1
Specimen Cup
59
27.8 + 0.4 mm (I .094 + 0.016 in. 29.4 + 0.8 mm (1.156 + 0.031 in. 45.0 ± 0.8 mm (1.77 ± 0.031 in. 54.0±0.1 mm (2.125 + 0.005 in. 4.0 + O.B rnm (0.156 -4- 0.031 in. 1.2 + 0.3 mm (0.049 + 0.010 in. 2.0 mm max (0.079 in. max)
D 56
+o
,iCJ
_ZJ
,"
I
A - - 7.15 mm B --
4.78 mm
C --
15.10 mm
D-
11.92 mm
E --
10.32 mm
Flame Size ~ Flame Size Bead U .~djustrn~i~t Burner~
Note: All dimensions!-0.13 mm unlessotherwiseshown. ,_ 2 0 . 6
/
i
# ~
Chamber
,
~k F - mm -'~, ,/
mm ,~ \~,~_
I 1 ~
ID-9 • •
84 mm •
, E E
Inch-Pound Equivalents mm 0.03 0.13 4.78 7.15 9.84
in. 0.001 0.005 0.188 0.281 0.387
mm 10.32 11.92 15.10 18.0 20.6
in. 0.406 0.469 0.594 0.71 0,81
NoTE--Dimensions relating to the size and position of the thermonteter colar are recommendedbut not mandatory. FIG. A1.2 Top of Ud Showing Position and Dimensions of Openings
95.3 mm Min. Dia.
In~-eoundSqulvslem
FIG. A1.3
60
mm
In.
6.4 82.6 95.3
0.25 3.25 3.75
Section of Liquid Bath end Test Cup (Manual Apparatus)
~
D 56
A2. VERIFICATION OF APPARATUS PERFORMANCE A2.1 Certified Reference Material (CRM)--CRM is a stable, pure (99+ mole % purity) hydrocarbon or other stable petroleum product with a method-specific flash point established by a method-specific interlabomtory study following ASTM RR:D02-1007 guidelines or ISO Guide 34 and 35. A2.1.1 Typical values of the flash point corrected for barometric pressure for some reference materials and their typical limits are given in Table A2.1 (see Note A2.3). Suppliers of CRMs will provide certificates stating the method-specific flash point for each material of the current production batch. Calculation of the limits for these other CRMs can be determined from the reproducibility value of this test method, reduced by interlaboratory effect and then multiplied by 0.7 (see Research Report RR:$15-1007).
NOTe A2.3---Materiah, purities, flash point values and limits stated in Table A2.1 were developed in an ASTM interlaboratory program (see RR:SIS-1010) to determine $uitability of use for verification fluids in
flash point test methods. Other natedals, purities, flash point values, and limi~l can be suitable when produced acoordin~ to the practices of
ASTM RR:D02-1007 or ISO Guides 34 and 35. Certificatesof performance of such materiah should be consultedbefore use, as the flash point value will vary dependent on the composition of each CRM batch. A2.2 Secondary Working Standard (SWS)---SWS is a stable, pure (99+ mole % purity) hydrocarbon, or other petroleum product whose composition is known to remain appreciably stable. A2.2.1 Establish the mean flash point and the statistical control limits (3#) for the SWS using standard statistical techniques. 12 NOTE A2.4---Thetypicalprocedureto arrive at the mean flashpoint is achieved by testing representative subsamples three times in an apparatus previouslyverifiedusing a CRM, statisticallyanalyzingthe results and, after outlier removal, calculatingthe arithmetical mean or by conductingan inteflaboratoryprogramwith three laboratories,each testing the representativesamplein duplicateand calculatingthe mean using standard statisticaltechniques.
NOTE A2.1--Supporting data for the interlaboratorystudy to generate the flash point in Table A2.1 can be found in research report RR:SI5-1010. TABLE A2.1
Hyemcmtxz n-decane n-undecam
D 56 Typical Flash Point VMues lind Typical Limits for CRM
Pumy(moteS)
FlashPo~t(°C)
Um~ (°f)
99+ 99+
50.9 67.1
:1:2.3 :e2.3
IsA S T M M N L 7 Manual on the Presen~ion of Dola ControlChart Analys~, 6th ed.,ASTM, 1990.
A3. CHECKING CONDITION CALIIIRATION AND OPERATION OF TAG CLOSED TESTER A3.1 Material: A3.1.1 1,4 Dimethylbenzene13 (p-Xylene), conforming to the following requirements: Specific gravity (15.6/15.6"C) (60/60"F), 0.860 min~ 0.866
A3.2 Procedure: A3.2.1 Determine the flash point of the 1,4 Dimethylbenzene, following the test procedures. When the tester is operating properly, a value of 27.2 :t: 0.6°C (81 :t: I°F) will be obtained. A3.2.2 When the flash point obtained on 1,4 Dimethylbenzene is not within the limits stated in A2.2.1, check the condition and operation of the apparatus to ensure conformity with the details listed in Annex A I, especially with regard to lightness of the lid (A1.1.2.2), the action of the shutter and the position of the ignition source (Al. 1.2.3), and the angle and position of the thermometer (Al.l.2.4). After adjustment, when necessary, repeat the test, with special attention to the procedural details prescribed in the test method. Also test a sample of Dimethylbenzene by gas chromatography to assure that it contains less than 500 ppm of Ca and hydrocarbons. Be sure to specify this level of purity.
max.
Boiling range . . . 2"C max from start to dry point, when tested by Test Method D 850 or Test Method D 1078. The range shall include the boiling point of pure 1,4 Dimethylbenzene, which is 138.4°C (281"F). Freezing p o i n t . . . 12.44°C (54.4°F), rain (99 % molal purity) as determined by Test Method D 1015. Contains less than 500 ppm of Ca and lighter hydrocarbons determined by gas chromatography using D 3798 (modified to allow reporting of Ce and fighter hydrocarbons) or a capillary boiling point column. n p-xylen¢obtainedfromany reputablechemicalsuppliermy be reed m calibratingfluidas longas theymeetthe _%~'scJ~,,mdetailedin A2.1.1.
A4. MANUFACrURING STANDARDIZATION A4.1 The cup thermometer, which conforms also to the specifications for the low-range thermometer used in the Pensky=Martens flash tester, Test Method D 93, is frequently supplied by the thermometer manufacturer with a metal or polytetrafluoroethylene ferrule intended to fit the collar on
the lid of the flash tester, This ferrule is frequently supple= mented by an adapter which is used in the larger=diameter collar of the Pensky=Martens apparatus, Differences in dimensions of these collars, which are immaterial in their effect on the result of tests, are a source of considerable
61
~ ) D 56
r.i
L.,
I I I
I
'I I
i I i
'I
I
I I I
I
I
!
f 5.3 mm
l
8.6 mm Dia. Min.
'
V"I __
!
Packing Ring
I
Soft Aluminum) 8.40 mm OD 7.23 mm ID 1.5 mm Thick
17.3 mm
I
]Y,;
-0.05 mm Inch-Pound Equivalents mm 0.05 5.3 7.1 FIG. A3.1
In. 0.002 0.21 0.28 Dimensions for Thermometer
mm 8.6 9.8 17.3
in. 0.34 0.385 0.68
Inch-Pound Equlv,,lents mm in. 1.5 0.06 7.23 0.284 8.40 0.3,30
Ferrule (Not Mandatory) FIG. A3.2
Dimensions for Thermometer
Mandatory)
Packing Ring (Not
A4. MANUFACTURING STANDARDIZATION unnecessary trouble to manufacturers and suppliers of instruments, as well as to users. A4.2 Subcommittee 21 on Metalware Laboratory Apparatus, of ASTM Committee E- 1 on Methods of Testing, has studied this problem and has established some dimensional requirements which are shown, suitably identified, in Figs. AI.I, A3.1, and A3.2. Conformity to these requirements is not mandatory but is desirable to users as well as suppliers of Tag closed testers.
A4.1 The cup thermometer, which conforms also to the specifications for the low-range thermometer used in the Pensky-Martens flash tester, Test Method D 93, is frequently supplied by the thermometer manufacturer with a metal or polytetrafluoroethylene ferrule intended to fit the collar on the lid of the flash tester. This ferrule is frequently supplemerited by an adapter which is used in the largeren J-Z LU ¢,3 Cr W ~ m
Z ~ 0 < U 0 0
0.25) they will interfere with the spectral peaks used for the hydrocarbon-type calculation.
7. Apparatus 7.1 Mass Spectrometer--The suitability of the mass spectrometer to be used with this method of analysis shall be proven by performance tests described herein. 7.2 Sample Inlet System--Any inlet system permitting the introduction of the sample without loss, contamination, or change in composition. To fulfill these requirements it will be necessary to maintain the system at an elevated temperature in the range of 125 to 325"C and to provide an appropriate sampling device. 7.3 Microburet or Constant- Volume Pipet.
and Z177 = Zjv.o N'5 [(177 + 14N) + (178 + 14N)].
(9)
11.2 Calculate the mole fraction at each carbon number of the alkylbenzenes for n = 10 to n = 18 as follows:
8. Calibration 8.1 Calibration coefficients are attached which can be used directly provided: 8.1.1 Repeller settings are adjusted to maximize the m/e + 226 ion of n-hexadecane. 8.1.2 A magnetic field is used that will permit scanning from role+ 40 to 292. 8.1.3 An ionization voltage of 70 eV and ionizing currents in the range 10 to 70 IxA are used. NOTE 3--The calibration coefficients were obtained for ion source conditions such that the ~;67/Z71 ratio for n-hexadecane was 0.26/1. The cooperative study of this test method indicated an acceptable range for this Z ratio between 0.2/I to 0.30/1. NOTE 4--Users of instruments other than Consolidated Electrodynamics Corp. Type 103 Mass Spectrometers may have to develop their own operating parameters and calibration data.
Ix. = [Pro - P m - t ( K , ) I / K 2 (10) where: ~t, = mole fraction of each alkylbenzene as represented by n which indicates the number of carbons in each molecular species. m --- molecular weight of the alkylbenzene being calculated, m - 1 = molecular weight minus 1, P = polyisotopic mixture peak at m, m - 1, K~ = isotopic correction factor (see Table 1), and K2 = mole sensitivity for n (see Table 1).
NOTE 6--This step of calculation assumes no mass spectral pattern contributions from other hydrocarbon types to the parentand parent-1 peaks of the alkylbenzenes. Selection of the lowest carbon number l0 is based upon the fact that C9 alkylbenzenes boil below 204"C (400*F) and their concentration can be considered negligible.
9. Performance Test 9.1 Generally, mass spectrometers are in continuous operation and should require no additional preparation before analyzing samples. If the spectrometer has been turned on only recently, it will be necessary to check its operation in accordance with this method and instructions of the manufacturer to ensure stability before proceeding. 9.2 Mass Spectral Background--Samples in the carbon number range C~o to C,s should p u m p out so that less than 0.1% of the two largest peaks remain. For example, background peaks from a saturate fraction at m/e + 69 and 71 should be reduced to less than 0.1% of the corresponding peaks in the mixture spectrum after a normal p u m p out time of 2 to 5 min.
l l . 3 Find the average carbon number of alkylbenzenes, A, in the aromatic fraction as follows:
A -- (Z.=,o"'tSn x V..)/(Z..lo"=ls#.)
the
(1 1)
11.4 Calculate the mole fraction at each carbon number of the naphthalenes for n = 11 to n = 18 as follows: TABLE 1
10. Mass Spectrometric Procedure 10.1 Obtaining the Mass Spectrum for Each Chromatographic Fraction--Using a microburet or constant-volume pipet, introduce sufficient sample through the inlet sample to give a pressure of 2 to 4 Pa (15 to 30 mtorr) in the inlet reservoir. (Warning--See Note 5.) Record the mass spectrum of the sample from m/e + 40 to 292 using the instrument conditions outlined in 8.1.1 through 8.1.3. NOTE 5: WarningJHydrocarbon samples of this boiling range are combustible.
Parent Ion Isotope Factors and Mole Sensitivities
Carbon No.
m/e
Isotope Factor, K1
Mole Sensitivity, K2
Alkylbenzenes 10 11 12 13 14 15 16 17 18
134 148 162 176 190 204 218 232 246
0.1101 0.1212 0.1323 0,1434 0.1545 0,1556 0,1767 0.1878 0.1989
85 63 60 57 54 51 48 45 42
L,
I-2
0.1201 0.1314 0.1425 0.1536 0.1647 0.1758 0.1871 0.1982
194 166 150 150 150 150 150 150
Naphthalenes 11 12 13 14 15 16 17 18
11. Calculations 11.1 Aromatic FractionmRead peak heights from the record mass spectrum corresponding to m/e + ratios of 67 to 347
142 156 170 184 198 212 226 240
fl~ D 2425 (12) x . = [Pro -- P m . , ( L ) I / L 2 where: -- mole fraction of each naphthalene as represented xn by n which indicates the number of carbons in each molecular species, rn -- molecular weight of the naphthalenes being calculated, m - 1 = molecular weight minus 1, P -- polyisotopic mixture peak at m, m - 1, L~ = isotopic correction factor (see Table 1), and /.2 ffi mole sensitivity for n (see Table 1). NOTE 7--This step of calculation assumes no mass spectral pattern contributionsto the parent and parent-1 peaks of the naphthalenes.The concentrationof naphthalene itselfat a molecularweightof 128 shall be determined separately from the polyisotopic peak at m/e+ 128 in the matrix calculation. The average carbon number for the naphthalenes shall be calculatedfrom carbon number 11 (molecularweight 142)to 18 (molecular weight 240).
11.5 Find the average carbon number of the naphthalenes, B, in the aromatic fraction as follows: B = (Z..,,"arccn)/(~,,,.,l'tSx.) 03) 11.6 Selection of pattern and sensitivity data for matrix carbon number of the types present. The average carbon number of the paraffins and cycloparaffins (Z71 and Z67, respectively) are related to the calculated average carbon of the alkylbenzenes (11.3), as shown in Table 2. Both Z71 and Z67 are included in the aromatic fraction matrix to check on possible overlap in the separation. The other types present, represented by Z's 103, 115, 153, and 151, are usually relatively low in concentration so that their parent ions are affected by other types present. The calculation of their average carbon number is not straight forward. Therefore, their average carbon numbers are estimated by inspection of the aromatic spectrum. Generally, their average carbon numbers may be taken to be equivalent to that of the naphthalenes, or to the closest whole number thereof, as calculated in 11.5. The average carbon number of tricyclic aromatics Z177 has to be at least C14 and in full boiling range middle distillates CI4 may be used to represent the ~177 types carbon number. From the calculated and estimated average carbon numbers of the hydrocarbon types, a matrix for the aromatic fraction is set up using the calibration data given in Table 3. A sample matrix for the aromatic fraction is shown in Table 4. The matrix calculations consist Relationship Between Average Carbon Numbers of Alkylbenzenes, Paraffins, and Cycloparaffins
TABLE 2
Alkylbenzenes
Paraffin and Cycloparaffin
Average Carbon No.
Average Carbon No.
10 11 12 13 14
11 12 13 15 (14.5) 16 (15.5)
348
in solving a set of simultaneous linear equations. The pattern coefficients are listed in Table 3. The constants are the Z values determined from the mass spectrum. Second approximation solutions are of sufficient accuracy. If many analyses are performed using the same type of a matrix, the matrix may be inverted for simpler, more rapid desk calculation. Matrices may also be programmed for automatic computer operations. The results of matrix calculations are converted to mass fractions by dividing by mass sensitivity. The mass fractions are normalized to the mass percent of the aromatic fraction, as determined by the separation procedure. I 1.7 Saturate FractionmRead peak at heights from the record of the mass spectrum corresponding to m/e + ratios of 67 to 69, 71, 81 to 83, 85, 91, 92, 96, 97, 105, 106, 119, 120, 123, 124, 133, 134, 137, 138, 147 to 152, 161 to 166, 175 to 180, 191 to 194, 205 to 208, 219 to 222, 233 to 236, 247 to 250. Find: Z71 = 71 + 85, (14) z67 = 67 + 68 + 69 + 81 + 82 + 83 + 96 + 97, (15) Y-123 = N~v.ojr-9 [(123 + 14N) + (124 + 14N)], (16) Y.149 = ~Jv.oJV- z [(149 + 14N) + (150 + 14N)], (17) 2;91 = Y.~v.oJr-6 [(91 + 14N) + (92 + 14N)]. (18) 11.8 Selection of the pattern and sensitivity data for matrix calculation is dependent upon the average carbon number of the types present. The average carbon number of the paraffins and cycloparaffin types (Z's 71, 69, 123, and 149), are related to the calculated average carbon number of the alkylbenzenes of the aromatic fraction (11.3), as shown in Table 2. The Y~91 is included in the saturate fraction as a check on the efficiency of the separation procedure. The pattern and sensitivity data for the Z91 are based on the calculated or estimated average carbon number from the mass spectra of the aromatic fraction (see 11.3). From the determined average carbon numbers of the hydrocarbon types, a matrix for the saturate fraction is set up using the calibration data given in Table 3. A sample matrix for the saturate fraction is shown in Table 5. The matrix calculations of the saturate fraction consists in solving a set of simultaneous linear equations. The results of the matrix calculations (second approximation solutions are sufficient) are converted to mass fractions by dividing by mass sensitivity. The mass fractions are normalized to the mass percent of the saturate fraction as determined by the separation procedure. 12. Precision and Bias 12.1 The precision of this tes: method as obtained by statistical examination of interlaboratory test results on samples having the composition given in Table 7 is as follows: 12.1.1 Repeatability---The difference between successive test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material, would be in the long run, in the normal and correct operation of the test method, exceed the values shown in Table 6 only in one case in twenty.
(~
TABLE 3 Hydrocarbon Type Carbon N o . . . Peaks read: ~71 ~67 ~123 ¢149 Z92 to 176 Z103 to 188 2;115 ~o 186 ~128 pk 2;141 2;153 Z151 ~177 Sensitivity: Mole Volume Mass
Paraffins 13
14.5
15.5
100 19
100 21
100 23 0.1
100 26 0.2
12
148 66 87
13
14.5
15.5
1.1 130 100 5
4
6
6
2
100 1
100 1
100 1
100 3
160 100 0.2
i'" 1
i'" 5
2 7
2 lO
. . . . . . . . .
2
2
. . . . . . . . .
170 70 92
192 74 97
238 81 104
416 165 204
439 170 209
220 107 122
302 145 180
347 153 191
Alkylbenzenes 11
Sensitivity: Mole Volume Mass
450 265 304
12
. . . .
13
0.3 0.4 0.7 2 0.1 0.2 1 1.5 100 100 10 10 4.5 5 1 1 . . . . . . . . . . . . . . . . . . . . . . . . . .
450 242 278
450 222 256
14 0.5 3 0.3 2 100 9 5 1
10 0.2 0.6
15 to 34A.a 100 20 to 12A,a 3
. . .... .
.
13
14.5
15.5
1.5 150 100 8
1 175 26 100 15 1
1 170 10 100 15 ...
2 150 20 100 20 3
.
.
.
12
0.4 1 0.1
0.4 1 1
1 2 2
01
02
450 206 237
thylenes or C"H='~e
Carbon N o . . .
12
12
13
380 280 288
13
03
.
420 276 288
.
.
420 250 263
.
.
.
10 0.3 0.3 0.4
298 117 134
220 118 124
268 150 158
298 127 135
.
.
.
13 1.7 6.0 4.8
Naphthalenes
10
11
0.5 0.8 0.2
09
17 15 100 100 25 25 7 ... 1.0 2.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.
268 137 156
18 100 28 5.4
.
.
Indenes or CnH2n.lo, or Both
11
.
Acsnaphthenes or CnH2~.14' or Both 13
.
Indans or Tetralins, or Both
Hydrocarbon Type
~141 2;153 ~151 ;~177 Sensitivity: Mole Volume Mess
15.5
4
......
0.3 0.7 0.1 1.3 100 9 4.4 0.7 . . . . . . . . . . . .
2;103 to 166 ZllSto186 ~.128 pk
14.5
Condensed Tdcycloparaffins
9'"
Peaks read: Z71 ~67 Z123 Z149 Z91to176 ~103 to 188 ~115 to 166 2;128 pk Z141 Z153 2;151 Z177
Peaks read: 2;71 2;67 Z91 to 176
13
Condensed Dicycloparaffins
0.5
Hydrocarbon Type Carbon No...
Patterns and Sensitivities for Middle Distillates
Noncondensed Cycloparaffins
12
...
D 2425
.
()i(~ 1.5 100 15
.
420 227 241
410 307 315
6.2 20.3 100 13 28 6.1 4.5
()11 0.6 11.4 100 •. . . . . . . . . . . . . .
0,6
.
372 196 200
236 211 184
.
.
.
.
.
12
13
5.2 1.2 0.5
1.5 1.5 7.8
2 2 4
01
07
05
0.9 0.1 23 0.7 100
1
1
0.1 19 5.6 100 8 7
0.1 18 5.6 100 10 7
.
.
360 2590 254
.
.
.
.
380 248 244
380 226 224
AcenaphTricyclic Aromatics 14
1 0.3 0.1
1 2 5
1 1 1
1 5 3
0.6 0.7
0:8 1
3 06 0.7
02 03 0.2
3 27 0.1
8 100 27 ...
10 100 20 4
1 17 100 ...
100 15
1.5 1.0 0.8 0.3 3.5 30 100
330 218 214
330 198 196
340 199 224
340 187 205
365 211 205
"-15"
Characteristic Mass Groupings
16
Peaks Read
~71 = 71, 85 2;67 = 67, 68, 69, 81, 82, 83, 96, 97 :~123 = 123, 134, 137, 138 up to 249, 250 2;149 = 149, 150, 163, 164 up to 247, 248 2;91 = 91, 92, 105, 106 up to 175, 176 2;103 = 103, 104, 117, 118, up to 187, 186 2;115 = 115, 116, 129, 130 up to 185, 186 2;128 = poly 128 pk 2;141 = 141,142, 155, 156 up to 239, 240 Z153 = 153, 154, 167, 168 up to 251,252 ~151 = 151,152, 165, 166 up to 249, 250 2;177 = 177, 178, 191,192 up to 247, 248
A = methyl indans. a tetralins.
349
Hydrocarbon Types
paraffins cycloparaffins, mono or noncondensed cycloparaffins condensed dicycloparaffins condensed tricycloparaffins alkylbenzenes indan or tetrains, or both C.H~.lo (indenes, etc.) naphthalene naphthalenes CnH~-14 (acenaphthenes, etc.) CnH~.le (acenaphthylenes, etc.) tricyclic aromatics
~) D 2425 TABLE 4
Hydrocarbon Type
Paraffins
Cycloparaffins
15.5
15.5
14
13
13
10
100 26 0.4
6 100 3 2 1
1 2 15 100 25 3
10 2
0.5 3 100 9 5 1 . . . . . . . .
1.7 6 6.2 203 100 13 28 6.1 4.5 0.6
439 170 209
450 206 237
372 198 200
236 211 184
Carbon No. . . . Peaks read: 2;71 2;67 2;91 2;103 2;115 2;128 pk 2;141 ¢153 2;151 2;177 Sensitivity: Mole Volume Weight
... ... 12 ... ... ...
238 81 105
Alkylbenzenes
Aromatic Concentration Matrix
013 2
. . . .
Indans and Tetralins
. . . .
. . . .
. . . . 420 227 241
TABLE 5
Indenes
Acenaphthenes CnH2n.14
Acenaphthylanes CnH2n.le
13
13
13
0.5 0.8 0.1 08 11.4 100 ... ...
2 2 1 01 18 5.6 100 10
1 2 5 3 0.8 0.7 10 100
1 5 3 3 2.7 0.1 ... 15
...
7
20 4
100 15
330 198 196
340 187 205
Naphthalene Naphthalenes
. . . . . . 380 226 224
14 0.6 0,7 18 15 1 0.8 0.3 3.5 30 100
365 211 205
Saturate Concentration Matrix
Paraffins
Monocycloparaffins
Dicycloparaffins
Carbon No. . . . . . . . . . . . . . . . .
15.5
15.5
15.5
15.5
14
2;71 2;67 2;123 2;149 2;91 Sensitivity: Mole Volume Weight
100 26 0.2
6 100 3
0.4
3
1.5 150 100 8 5
2 150 20 100 20
0.5 3 0.3 2 100
238 81 105
439 170 209
298 117 134
298 127 135
450 206 237
Hydrocarbon Type
TABLE 6
Compound Saturate Fraction: Paraffins Monocycioparaffins Dicycloparaffins Tdcycioparaffins Alkylbenzenes Aromatic Fraction: Paraffins Cycloparaffins Alkylbenzanes Indan and/or tetralins CnH2n-10 Naphthalenes C,,H2n-14 CnH2n-16 C,,H2n-18
Tdcydic Aromatics
TABLE 7
Precision of M e t h o d
Concentration Mass. ~
Repeatability
Reproducibility
40 to 50 18 to 25 6 to 12 1 to 5 0 to 3
0.5 1.1 0.7 0.3 0.2
4.0 5.2 4.4 2.0 0.3
0 to 2 0 to 2 3 to 8 2 to 5 0 to 4 3 to 8 0 to 3 0 to 3 0 to 3
0.4 0.5 0.3 0.3 0.3 0.3 0.1 0.3 0.1
0.6 0.9 1.4 0.5 0.7 1.0 0.9 0.7 0.4
Component Sample No. 7D: Paraffins Monocycloparaffin Dicyloparaffin Tdcycloparaffin AIkylbenzane Sample No. 8E: Paraffins Cycioparaffin Alkylbenzene tndan and/or tetralin C, H2n-10 Naphthalenes C,H2n-14 CnH2n-16 CnH2n-18
Tdcycloparaffins
Alkyl. benzenes
Composition of S a m p l e s T e s t e d A
Mean. Mass. ~
o,e
o~ c
44.25 22.04 8.54 2.84 0.33
0.16 0.34 0.23 0.11 0.04
1.30 1.70 -1.42 0.64 0.10
0.07 0.75 5.10 3.65 2.05 5.15 2.50 1.65 1.05
0.14 0.15 0.10 0.09 0.08 0.08 0.04 0.10 0.04
0.14 0.25 0.44 0,14
0.20 0.29 0.26 0.18 0.14
A Twelve laboratories cooperated and each sample was run twice, a er = repeatability standard deviation. c OR = reproducibility standard deviation. O Sample No. 7 - saturate fraction of • virgin middle distillate (78.0 wt % of tot=d). E Sample No. 8 = aromatic fraction of a virgin middle distillate (22.0 wt ~ of total).
350
fl~ D 2425 12.1.2 Reproducibility---The difference between two tingle and independent results, obtained by different operatots working in different laboratories on identical test material, would in the long run, in the normal and correct operation of the test method, exceed the values shown in Table 6 only in one ease in twenty.
NOTE 9--The precision for this test method was not obtained in accordance with RR:D02-1007.3 12.2 Bias--Bias cannot be determined because there is no acceptable reference material suitable for determining the bias for this test method. 13. Keywords 13.1 hydrocarbon types; mass spectrometry; middle distillates
NOTE 8--If samples are analyzed that differ appreciably in composition from those used for the interlaboratory study, this precision statement may not apply.
3 Annual Book of ASTM Standards, Vol 05.03. The American Society for Testing and Materials takes no position respact/ng the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and ff not revised, either reepproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at • meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received e fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
351
q~]l ~ Designation: D 2426 - 93
~Amerlc~St~darO
Standard Test Method for Butadiene Dimer and Styrene in Butadiene Concentrates by Gas Chromatography I This standard is issued under the fixed designation D 2426; the number immediately following the desisnation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon O) indicates an editorial change since the last revision or re.approval.
1. Scope 1.1 This test method covers the determination of butadiene dimer (4-vinylcyclohexene-l) and styrene in butadiene concentrates, both "recycle" and specification grade. 1.2 The values stated in SI units are to be regarded as the standard. 1.3 This standard does not purport to address all of the
safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements see Notes 1, 2, and 4.
2. Referenced Documents
2.1 ASTM Standards: D 1265 Practice for Sampling Liquefied Petroleum (LP) Gases2 D 1657 Test Method for Density or Relative Density of Light Hydrocarbons by Pressure Thermohydrometer 2 D 1945 Test Method for Analysis of Natural Gas by Gas Chromatography 3 D2593 Test Method for Butadiene Purity and Hydrocarbon Impurities by Gas Chromatography 2 E 260 Practice for Packed Column Gas Chromatography 4
suitable for use in internal quality control and in establishing product specifications.
5. Apparatus 5.1 Chromatograph--Any chromatograph having either a thermal conductivity or flame ionization detector may be used. The detector system shall have sufficient sensitivity to obtain a deflection of at least 2 mm at a signal-to-noise ratio ofat least 5:1 for 0.01 weight % ofbutadiene dimer and styrene under the operating conditions prescribed in this test method. 5.2 Recorder--A 0 to l-mV, 0 to 5-mV, or 0 to lO-mV recorder with a full-scale response time of 2 s or less, and with sufficient sensitivity to meet the requirements of 5. I. 5.3 Column--Any column may be used that is capable of resolving the butadiene dimer and styrene as discrete peaks, quantitatively proportional to concentration and within an elapsed time sufficiently short to be practical. (See Note 1.) 5.4 Liquid Sampling Valve--Any liquid sampling valve may be used that will permit the reproducible introduction of the butadiene concentrate as a liquid under its vapor pressure or higher and in a quantity sufficient to meet the sensitivity and resolution requirements in 5.1 and 5.3, respectively. 5 6. Reagents and Materials 6.1 4- Vinylcyclohexene.1 and Styrene, for calibration, purity of not less than 99 %. 6.2 Carrier Gas--Helium or hydrogen for use on thermal conductivity detector units; or nitrogen, helium, or argon for use on ionization detector units.
3. Summary of Test Method 3.1 The sample is introduced into a gas-liquid partition column. The components of interest are separated as they are transported through the column by a carrier gas, and their presence in the effluent is detected and recorded as a chromatogram. Packed columns are used, and either thermal conductivity or ionization detectors are permissible. The quantity of the components of interest present in the sample is determined from the chromatogram by comparing their peak areas or heights with those obtained from a synthetic sample.
NOTE 1: Warning----Compressed gas. H a z a r d o u s pressure. NOTE 2: W a r n l n g - - H y d r n g e n gas is flammable. Hazardous pressure.
6.3 Liquid Phase, for column. NOTE 3 - - T h e following materials have been used successfully as liquid phases: Carbowax 400, 1500, i 540
4. Significance and Use 4.1 Butadiene dimer and styrene may be present as impurities in commercial butadiene. This test method is
General Electric SE-30 siliconegum rubber Polyethyleneglycol6000 Barecowax 1035 Dow Coming silicone oil Carbowax 20M + Dow Coming Hi Vae.
This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.0D on Hydrocarbons for Chemical and Special Uses. Current edition approved Feb. 15, 1993. Published May 1993. Originally published as D 2426 - 65 T. Last previous edition D 2426 - 86. 2 Annual Book of ASTM Standards, Vol 05.01. Annual Book of ASTM Standards, Vol 05.05. Annual Book of ASTM Standards, Vol 14.01.
6.4 Solid Support, for use in packed column, usually crushed fire brick or diatomaceous earth. Sieve size will depend on the diameter of the column used and support s Suitable valves are commercially available.
352
~[~) D 2426 loading and should be such as to give optimum resolution and analysis time.
Area methods found to be acceptable include planimetering, integration, and triangulation (multiplying the peak height by the width at the half-height). In peak area or height methods care must be taken so that chromatograph operating parameters such as column temperature and carrier gas flow rate are kept at the same conditions on botli the synthetic standard and the sample. Calculate the percentage by weight of each component as follows: Concentration, weight% = (A,/Ao) x S x (Go/Gs) (1) where: As = peak area or height of component in the sample, Ao = peak area or height of component in the synthetic
7. Preparation of Apparatus 7.1 Column PreparationmAny satisfactory method, used in the practice of the art, that will produce a column meeting the requirements of 5.3. See Appendix X2 of Method D 1945, also see 6.1 of Test Method D 2593. 7.2 Chromatograph--Put in service in accordance with the manufacturer's instructions. The injector temperature shall be no greater than 5°C above the column oven temperature. The column oven temperature shall not exceed 185"C. See Table 1 for typical operating conditions. 7.3 Synthetic Blends--Prepare a synthetic mixture from 99 tool % minimum pure 4-vinylcyclohexene-I and styrene in a suitable matrix in approximately the same concentration expected in the sample. The matrix may be any one of the normal paraffin hydrocarbons from butane to heptane, inclusive. In preparing the blend, weigh each compound added with sufficient precision to result in a mixture accurate to 5 % relative or 0.02 % absolute, whichever is greater. Transfer the blend to a container of the type to be used for the sample and pressure with a suitable gas.
blend, S = weight % of component in the synthetic blend, Gs = relativedensity 60/60 of the sample, and Go = relativedensity 60/60 of the synthetic blend. NOTE 5 - - T h e specific gravity of the sample may be determined in
accordance with Test Method D 1657 and the specificgravity of the syntheticmay be assumedto be equal to the gravityof solvent used to prepare the blend. A list of such gravities is found in STP 109 A, Physical Constants of Hydrocarbons.Ca to C~o.6 10. Precision and Bias I0.1 The precision of this test method as determined by statistical examination ofinterlaboratory results is as follows: 10.1.I Repeatability--The difference between successive test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, and in the normal and correct operation of the test method, exceed the following values only in one case in twenty:
8. Procedure 8.1 Using the liquid sampling valve, inject into the column the desired volume of synthetic blend and record the peaks at a sensitivity setting that allows the maximum peak height. Pressure the sample cylinder with a suitable gas to a pressure sufficient to ensure no flashing in the line to the sampling valve or in the valve itself. Using the same sample size and instrument conditions, inject the sample into the column and record the peaks. (See Table 1 for typical operating conditions.)
Repeatability 0.005 0.044
10.1.2 Reproducibility--The difference between two single and independent results obtained by different operators working in different laboratories on identical test material would, in the long run, and in the normal and correct operation of the test method, exceed the following values only in one case in twenty:
NOTe 4: Warning--Butadienegas is flammableunder pressure. 9. Calculation 9.1 Peak MeasurementmMeasure the peak area or height of each component of interest in both the synthetic blend and the sample. Measurement may be accomplished by any method that meets the precision requirements of Section 10. TABLE 1
Concentration 0.15 1.49
Dimer, wt % Styrene, wt %
6 Available as a separate publication from ASTM.
Columns and Conditions Used Successfully ~ a +xDow 20M Coming HI Vac
Polyethylene C~ycol-6000
Barecowax 1035
iC,oatecr)
3.1 6.4 100-128 0.75 each Silica
3.7 4.8 155 30 Chromosorb P
8.1 6.4 140 20 Chr(:xnoso~ P
30050
50-80
eo
i5
~
171
o0
HFI 0.07 integrator
HFI 1.54 triangulation
T.C. 1.03 triangulation
T.C. 8.69 peak height
T.C. 3.0 planimeter
DOW Silicone 200
Carbowax 1500
Carbowax 1540
Colurnn length, m Column diameter, mm ~ n temperature, °C liquid phase, wt '~ Support material
1.5 3.2 85 10 C,hromosorb P
4.6 4.8 110 15 TFEfluorocarbon
3.7 6.4 100 16 Chromosorb P
Mesh Carder flow, mL/min Detector Sarnpla size, pL Peek measurement
80-100 19 HFP 0.77 triangulation
eo T.C. a 20 triangulation
Silicone SE-80 15.2 0.5 75
lOO-12o
A HFI ,,, hydrogen flame ionization. B T.C. ,, thermal conductivity.
353
~1~ D 2426 Concentration Dimer,wt % Styrene,wt M
0.15
1.49
Reproducibility 0.018 0.051
method for measuring Dimer and Styrene, bias has not been determined.
10.2 Bias-.~ince there is no accepted reference material suitable for determining the bias for the procedure in this test
11. Keywords 11.1 butadiene concentrate; butadiene dimmer; gas chromatography; Styrene
The ~ Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned In this standard. Users of this standard are expresaly edvlaed that dstermlnstlon of the validity of any such pstant r~hts, and the risk of Infr~ngemontof ~ riglea, are entirety thor own respon~bitity. stondud Is subject to revlalon at any time by the responsible t ~ h n l ~ l ~mmittee and must be reviewed every five years and if not revlud, either r e w ~ or withdrawn. Your ~ e n a n ~ are Invited alther for revlalon of this standerd or for additionalstandards and ehould be eddreesed to ASTM Headquarters. Your ¢~=rnmantRwill receive careful consldenltion st • meeting of the responsible technical oornmibee, which you may attend. If you feel that your commer~s have not received • fair hearing you ahould make your view• known to the ASTM Committee on Standards, 1916 Race St., Ph//edalph/a, PA 10103.
354
Designation: D 2500 - 91
®
An Amerk:an National Standard Bfltlsh Standard 4458
Designation: 219/82
Standard Test Method for Cloud Point of P e t r o l e u m Products I This standard is issued under the fixed designation D 2500; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (0 indicates an editorial change since the last revision or rcapproval.
This test method was adopted as an ASTM-IP Standard. This standard has been approvedfor use by agencies of the Department of Defense. Consult the DoD Index of Specifications and Standards for the specific year of issue which has been adopted by the Department of Defense.
1. Scope 1.1 This test method covers only petroleum products which are transparent in layers 40 mm in thickness, and with a cloud point below 49°C.
U
~.-~
1.2 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicabtTity of regulatory limitations prior to use. For specific
E M
m
L
~
-!7
hazard statements see Notes 2, 3, 4, and 5.
2. Referenced Documents
lmT4qt
2.1 A S T M Standard: E 1 Specification for ASTM Thermometers 2 2.2 IP Standard: Specifications for IP Standard Thermometers 3
m mklN
[] [ ]
m
3. Terminology 3.1 Description of Term Specific to This Standard: 3.1.1 cloud pointmthe temperature at which a cloud of wax crystals first appears in a liquid when it is cooled under conditions prescribed in this test method.
iiMn M anfalm* It mllmstlm
FIG. 1 Apparatus for Cloud Point Test
4. Summary of Test Method 4. I The sample is cooled at a specified rate and examined periodically. The temperature at which a cloud is first observed at the bottom of the test jar is recorded as the cloud point.
inside diameter of the jar may range from 30 to 32.4 mm within the constraint that the wall thickness be no greater than 1.6 ram. The jar should be marked with a line to indicate sample height 54 + 3 mm above the inside bottom. 6.2 Thermometers, having ranges shown below and conforming to the requirements as prescribed in Specifications E I or Specifications for IP Standard Thermometers.
5. Significance and Use 5.1 The cloud point of a petroleum product is an index of the lowest temperature of its utility for certain applications.
6. Apparatus (See Fig. 1) 6.1 Test Jar, clear, cylindrical glass, fiat bottom, 33.2 to
Thermometer
Temperature Range
34.8-mm outside diameter and 115 and 125-mm height. The
High cloud and pour Low cloud and pour
This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direft responsibility of Subcommittee D02.07 on Flow Properties. Current edition approved Oct. 15, 1991. Published December 1991. Originally published as D 2500 - 66. Last previous edition D 2500 - 88. 2 Annual Book of ASTM Standards, Vol 14.01. 3 Available from 61 New C4wendish St., London, England WIM BAR.
6.3 Cork, to fit the test jar, bored centrally for the test thermometer. 6.4 Jacket, metal or glass, watertight, cylindrical, flat bottom, about 115 mm in depth, with an inside diameter of 44.2 to 45.8 mm. It must be supported free of excessive vibration and firmly in a vertical position in the cooling bath 355
-38 to +50"C -80 to +20"C
Thermometer Number ASTM IP 5C 6C
IC 2C
~
D 2500 -36*C. Adjust the position of the cork and the thermometer so that the cork fits tightly, the thermometer and the jar are coaxial, and the thermometer bulb is resting on the bottom of the jar. NOTE 6--Liquid column separation of thermometers occasionally occurs and may escape detection. Thermometers should be checked immediately prior to the test and used only if their ice points are 0 + I'C, when the thermometer is immersed to the immersion line in an ice bath, and when the emergent column temperature does not differ significantly from 21"C. Alternatively, immerse the thermometer to a reading and correct for the resultant cooler stem temperature.
of 6.7 so that not more than 25 m m projects out of the cooling medium. 6.5 Disk, cork or felt, 6 mm thick to fit loosely inside the jacket. 6.6 Gasket, ring form, about 5 mm in thickness, to fit snugly around the outside of the test jar and loosely inside the jacket. The gasket may be made of rubber, leather, or other material which is elastic enough to cling to the test jar and hard enough to hold its shape. Its purpose is to prevent the test jar from touching the jacket. 6.7 Bath or baths, maintained at prescribed temperatures with a firm support to hold the jacket vertical. The required bath temperatures may be maintained by refrigeration if available, otherwise by suitable freezing mixtures. NOTE I--The mixtures commonly used for temperatures down to those shown are as follows: ice and water 10°C Crushed ice and sodium chloride crystals Crushed ice and calcium chloride crystals Acetone, methyl or ethyl alcohol, or petroleum naphtha chilled in a covered metal beaker with an ice-salt mixture to - 12"C, then with enough solid carbon dioxide to five the desired temperature
8.4 See that the disk, gasket, and the inside of the jacket are clean and dry. Place the disk in the bottom of the jacket. The disk and jacket shall have been placed in the coofing medium a minimum of 10 min before the test jar is inserted. The use of a jacket cover while the empty jacket is cooling is permitted. Place the gasket around the test jar, 25 m m from the bottom. Insert the test jar in the jacket. Never place a jar directly into the cooling medium.
-12"(:: -26"C -57"C
NOTE 7--Failure to keep the disk, gasket and the inside ofthe jacket clean and dry may lead to frost formation which may cause erroneous results.
7. Reagents and Materials
7.1 Acetone--Technical grade acetone is suitable for the cooling bath, provided it does not leave a residue on drying. NOTE 2: Warning--Extremely flammable. 7.2 Calcium ChloridemCommercial or technical grade calcium chloride is suitable. 7.3 Carbon Dioxide (Solid) or Dry IcemA commercial grade of dry ice is suitable for use in the cooling bath. 7.4 Ethanol or Ethyl Alcohol--A commercial or technical grade of dry ethanol is suitable for the cooling bath. NOTE 3: Warning--Flammable. Denatured, cannot be made nontoxic. 7.5 Methanol or Methyl Alcohol--A commercial or technical grade of dry methanol is suitable for the cooling bath. NoTE 4: Warning--Flammable. Vapor harmful. 7.6 Petroleum Naphtha--A commercial or technical grade of petroleum naphtha is suitable for the cooling bath. NOTE 5: Warning--Combustible. Vapor harmful. 7.7 grade 7.8 dium
Sodium Chloride Crystals--Commercial or technical sodium chloride is suitable. Sodium Sulfate--A reagent grade of anhydrous sosulfate should be used when required (see Note 7).
8. Procedure 8.1 Bring the oil to be tested to a temperature at least 14°C above the approximate cloud point. Remove any moisture present by a method such as filtration through dry lintless filter paper until the oil is perfectly clear, but make such filtration at a temperature of at least 140C above the approximate cloud point. 8.2 Pour the clear oil into the test jar to the level mark. 8.3 Close the test jar tightly by the cork carrying the test thermometer. Use the High Cloud and Pour Thermometer if the expected cloud point is above -36*C and the Low Cloud and Pour Thermometer if the expected cloud point is below
8.5 Maintain the temperature of the cooling bath at - l to +2°C. 8.6 At each test thermometer reading that is a multiple of I°C, remove the test jar from the jacket quickly but without disturbing the oil, inspect for cloud, and replace in the jacket. This complete operation shall require not more than 3 s. If the oil does not show a cloud when it has been cooled to 10°C, transfer the test jar to a jacket in a second bath maintained at a temperature o f - 18 to -15°C (see Table 1). Do not transfer the jacket. If the oil does not show a cloud when it has been cooled to -7°C, transfer the test jar to a jacket in a third bath maintained at a temperature o f - 3 5 to -32"C. For the determination of very low cloud points additional baths are required, each bath to be maintained at 17"C below the temperature of the preceding bath (see Table I). In each case transfer the jar to the next bath when the temperature of the oil comes to 28°C above the low end of the temperature setting of the temperature of the next bath (see Table I). 8.7 Report the cloud point, to the nearest I'C, at which any cloud is observed at the bottom of the test jar, which is confirmed by continued cooling. NOTE 8--A wax cloud or haze is always noted first at the bottom of the test jar where the temperature is lowest. A slight haze throughout the entire sample, which slowlybecomes more apparent as the temperature is lowered, is usually due to traces of water in the oil. Generally this water haze will not interfere with the determination of the wax cloud point. In most cases of interference, t'fltration through dry lintless filter papers such as described in 8. I is sufficient. In the case of diesel fuels, however,if the haze is very dense, a fresh portion of the sample should be dried by shaking 100 mL with 5 g of TABLE 1
Bath 1 2 3 4 5
356
Bath and Sample Temperature Ranges
Bath Temperature Setting, °C -1 to2 -18 to -15 -35 to -32 -52 to -49 -69 to -66
Sample Temperature Range, °C Start to 10 10 to - 7 - 7 to -24 -24 tO -41 -41 to -58
q~) D 2500 suits, obtained by the same operator with the same apparatus under constant operating conditions on identical test matedal, would in the long run, in the normal and correct operation of this test method exceed 2"C for distillate oils and 6"C for other oils only in one case in twenty. 10.3 Reproducibility--The difference between two single and independent results obtained by different operators working in different laboratories on identical test material, would in the long run, in the normal and correct operation of this test method, exceed 4"C for distillate oils and 6"C for other oils only in one case in twenty. 10.4 Bias--The procedure in this test method has no bias, because the value of cloud point can be defined only in terms of a test method.
anhydrous sodium sulfate for at least 5 min and then filtering through dry lintless filter paper. Given sufficient contact time, this procedure will remove or sufficiently reduce the water haze so that the wax cloud can be readily discerned. Drying and filtering should be done always at a temperature at least 14"C above the approximate cloud point but otherwise not in excess of
49"C.
9. Report 9.1 Report the temperature recorded in 8.7 as the Cloud Point, Test Method D 2500. 10. Precision and Bias 10.1 The precision of this test method as determined by statistical examination of interlaboratory results is as follows: 10.2 Repeatability--The difference between two test re-
11. Keywords 11.1 cloud point; petroleum products; wax crystals
The American Society for Testing and Materials takes no position respecting the vahdlty of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the vahdlty of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is sublect to rewslon at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend If you feel that your comments have not received a fair hearing you should make your wews known to the ASTM Committee on Standards, 100 Bart" Harbor Drive, West Conshohocken, PA 19428.
357
(~l~ Designation: D 2501 - 91 Standard Test Method for Calculation of Viscosity-Gravity Constant (VGC) of Petroleum Oils 1 This standard is issued under the fixed designation D 2501; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
3. Summary of Test Method 3.1 The kinematic viscosity at 40"C (104*F) and the density at 15"C of the oil are determined. If the oil is extremely viscous, or if it is otherwise inconvenient to determine the viscosity at 40"C, the kinematic viscosity at 100*C (212"F) can be used. The viscosity-gravity constant is calculated from the measured physical properties using the appropriate equation.
1. Scope 1.1 This test method covers the calculation of the viscosity-gravity constant (VGC) of petroleum oils2 having viscosities in excess of 4 cSt. = 4 x 10 - 6 m-2/s at 40"C (104°F). 1.2 Annex A 1 describes a method for calculating the VGC from Saybolt (SUS) viscosity and relative density. 1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 1.4 The values stated in either acceptable SI units or in other units shall be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system must be used independently of the other, without combining values in any way.
4. Significance and Use 4.1 The viscosity-gravity constant (VGC) is a useful function for the approximate characterization of the viscous fractions of petroleum. 2 It is relatively insensitive to molecular weight and is related to a fluids composition as expressed in terms of certain structural elements. Values of VGC near 0.800 indicate samples of paraftinic character, while values close to 1.00 indicate a preponderance of aromatic structures. Like other indicators of hydrocarbon composition, the VGC should not be indiscriminately applied to residual oils, asphaltic materials, or samples containing appreciable quantities of nonhydrocarbons.
2. Referenced Documents 2.1 A S T M Standards: D 287 Test Method for API Gravity of Crude Petroleum and Petroleum Products (Hydrometer Method) 3 D445 Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and the Calculation of Dynamic Viscosity)3 D 1298 Test Method for Density, Relative Density (Specific Gravity), or API Gravitt of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method 3 D2140 Test Method for Carbon-Type Composition of Insulating Oils of Petroleum Origin 4 D 4052 Test Method for Density and Relative Density of Liquids by Digital Density M e t e : 2.2 Other Document: ASTM-IP Petroleum Measurement Tables 6
5. Measurement of Physical Properties 5.1 Preferably, determine the kinematic viscosity at 400C as described in Test Method D 445. However, if the sample is extremely viscous or if it is otherwise inconvenient to measure the viscosity at 40oc, the viscosity at 100oc may be determined. 5.2 Determine the density at 15oc in accordance with Test Method D 1298 or Test Method D 4052. Equivalent results can be obtained by determining API Gravity at 60*F (15.560C) in accordance with Test Method D287, and converting the result to density at 15oc by means of Table 3 of the Petroleum Measurement Tables (American Edition). 6 NOTE l - - l f it is necessary to convert a result obtained using the digital density meter to a density at another temperature, the Petroleum Measurement Tables can be used only if the glass expansion factor has been excluded.
This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D 02.04 on Hydrocarbon Analysis. Current edition approved Oct. 15, 1991. Published December 1991. Originally published as D 2501 - 66. Last previous edition D 2501 - 87. 2 Coats, H. B., and Hill, J. B., Industrial and Engineering Chemtstry, Vol 20, 1928, p. 641. 3 Annual Book oJ ASTM Standards, Vol 05.01. 4 Annual Book of ASTM Standards, Vol 10.03. ~ Annual Book of ASTM Standards, Vol 05.03. ~' Published jointly by, and available from the American Society of Testing and Materials, 1916 Race St., Philadelphia, PA 19103, and the Institute of Petroleum, 61 New Cavendish St., London WIM 8AP, Compamon volumes--the British Edition and the Metric Edition--are also available. These tables supersede all other similar tables previously published by either of these societies and the National Bureau of Standards Circular C-410 and the supplement to Circular C-410.
6. Calculation of Viscosity-Gravity Constant 6.1 From Kinematic Viscosity at 40°C and Density at 15°C--Use the following equation to calculate the VGC from the measured properties: VGC =
G - 0.0664 - 0.1154 Log(V- 5.5) 0.94 - 0.109 Log(V- 5.5)
where: G = density at 150C, g/mL, and V = kinematic viscosity at 400C, eSt.
358
(1)
~
D 2501
6.2 From Kinematic Viscosity at IO0*C and Density at 15*C--Use the following equation to calculate the VGC: VGC
=
G - 0.108 - 0.t255 Log(V' - 0.8) 0.90 - 0.097 L o g ( V '
-
where: r r = precision of the VGC, rcs = precision of the gravity from D 287, rv = precision of the viscosity from D 445, V = measured viscosity, and Y = VGC. 8.2.2 For viscosity measured at 100*C,
(2)
0.8)
where: G = density at 15"C, g/mL, and V' = kinematic viscosity at 100*C, cSt.
1
r~,-- 0.90 - 0.097 logjo ( V - 0.8)
7. Report
7.1 Report the calculated VGC to the nearest .002 unit. 7.2 If the viscosity at 100*C was used for the calculation, state this in the report.
•
8.1 The calculation of viscosity-gravity constant from kinematic viscosity at 40°C and density at 150C is exact. Precision limits are not assigned to this calculation. 8.2 The precision of the calculated VGC is dependent only on the precision of the original determinations of viscosity and density• Those precision statements are found in their respective test methods. The precision can be calculated as follows: 8.2.1 For viscosity measured at 40"C, 1
•
" r~7 0.00177(Y- 1.294)2 r°- + ( V - 0.8)2
8.3 The VGC calculated from the viscosity at 100*C can differ slightly from that calculated from the viscosity at 40"C. A statistical evaluation of VGC data derived from equivalent viscosities at both 100*F and 210*F suggests that in the range from about 0.80 to 0.95 VGC, the expected average difference will be approximately 0.003 units. Whenever possible, it is preferable to determine the VGC using Eq 1. 8.4 Bias--The procedure in Test Method D 2501 for calculation of viscosity-gravity constant has no bias because the value of viscosity-gravity constant can be defined only in terms of a test method. 8.5 The term viscosity-gravity constant is also used in Test Method D 2140, for determining carbon-type composition of insulating oils of petroleum origin. The equations used are different from those in this test method; the bias between the two test methods is unknown.
8. Precision and Bias
rr = 0.94 - 0.109 loglo ( V - 5.5)
(4)
(3) ,0.00224 ( Y - 1.059)2 ( V - 5.5)2
r(i 2 dr. r l , .
9. Keywords 9.1 aromatic; density; kinematic viscosity; paraffinic
ANNEX (Mandatory Information)
AI. CALCULATION OF VISCOSITY-GRAVITY CONSTANT FROM SAYBOLT VISCOSITY AND RELATIVE DENSITY (SPECIFIC GRAVITY) A I. 1 The calculation of viscosity-gravity constant (VGC) can also be calculated from viscosity in units of Saybolt seconds universal (SUS) and relative density (specific gravity). AI.2 From Saybolt Viscosity at IO0*F and Relative Density (Specific Gravity) 60~60*F--Use the following equation to calculate the VGC from the measured properties:
VGC =
10G - 1.0752 log ( V - 38) 10 - log ( V - 38)
sity (Specific Gravity) 60/60*F--Use the following equation to calculate the VGC: VGC=
G - 0.12441og(V~ - 31) -0.0839 0.9255 - 0.0979 log(V1 - 31)
(All)
where: G = relative density (specific gravity) at 60/60"F, and V, = Saybolt Universal viscosity at 210*F. A I.4 The viscosity-gravity constant calculated from the Saybolt viscosity at 210*F can differ slightly from that calculated from the 100*F viscosity• A statistical evaluation of VGC data derived from both the 100*F and 210*F viscosities suggests that in the range from about 0.80 to 0.5 VGC, the expected average difference will be approximately 0.003 units. Whenever possible, it is preferable to determine the VGC using Eq A 1.1.
(AI.1)
where: G = relative density (specific gravity) at 60/60"F, and V = Saybolt Universal viscosity at 100*F. A1.3 From Saybolt Viscosity at 210"F and Relative Den-
359
fl~ D 2501 The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
360
(I~T~ Designation: D 2502 - 92
An Arnerican National Standard
Standard Test Method for Estimation of Molecular Weight (Relative Molecular Mass) of Petroleum Oils From Viscosity Measurements 1 This standard is issued under the fixed designation D 2502; the number immediatel~ lbllo~ing the designation indicates the year of original adoption or, in the ease of revision, the year of last revision. A number in parcnthe~s indicates the year of last reapproval. A superscript epsilon (E) indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 This test method covers the estimation of the mean molecular weight (relative molecular mass) of petroleum oils from kinematic viscosity measurements at 100 and 210*F (37.78 and 98.89"C). 2 It is applicable to samples with molecular weights in the range from 250 to 700 and is intended for use with average petroleum fractions. It should not be applied indiscriminately to oils that represent extremes of composition or possess an exceptionally narrow molecular weight (relative molecular mass) range. 1.2 Values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are provided for information purposes only. 1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate sa~,ty and health practices and determine the applicability of regulatory limitations prior to use.
4.2 Molecular weight (relative molecular mass) is a fundamental physical constant that can be used in conjunction with other physical properties to characterize hydrocarbon mixtures. 5. Procedure 5.1 Determine the kinematic viscosity of the oil at 100 and 210*F (37.78 and 98.89"C) as described in Test Method D 445. 5.2 Look in Table 1 for 100*F (37.78"C) viscosity and read the value of H that corresponds to the measured viscosity. Linear interpolation between adjacent columns may be required. 5.3 Read the viscosity - molecular weight chart for H and 210*F (98.89"C) viscosity. A simplified version of this chart is shown in Fig. 1 for illustration purposes only (Note). Interpolate where necessary between adjacent lines of 210*F viscosity. After locating the point corresponding to the value of H (ordinate) and the 210*F viscosity (superimposed lines), read the molecular weight along the abscissa. Example: Measured viscosity, cSt: 100*F (37.78"C) = 179 210*F (98.89"C) = 9.72 Look in Table 1 for 179 and read the corresponding value H = 461. Using H = 461 and 210*F viscosity = 9.72 in conjunction with chart gives molecular weight (relative molecular mass) = 360 (see Fig. 1).
2. Referenced Documents
2.1 ASTM Standard: D445 Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and the Calculation of Dynamic Viscosity)3 2.2 Adjunct: Molecular Weight of Petroleum Oils from Viscosity Measurements (D 2502) 4 3. Summary of Test Method 3.1 The kinematic viscosity of the oil is determined at 100 and 21O°F (37.78 and 98.89°C). A function " H " of the 100°F viscosity is established by reference to a tabulation of H function versus 100*F viscosity. The H value and the 210*F viscosity are then used to estimate the molecular weight from a correlation chart.
NOTE I--A 22 by 28-in. (559 by 711-mm) chart available as an adjunct to this test method was used in cooperative testing of the method. If other charts are used, the precision statements given in the Precision Section will not apply. 5.4 Report the molecular weight to the nearest whole number.
4. Significance and Use 4.1 This test method provides a means of calculating the mean molecular weight (relative molecular mass) of petroleum oils from another physical measurement.
6. Precision and Bias 6.1 The precision of this test method as obtained by statistical examination of interlaboratory test results is as follows: 6.1.1 Repeatability--The difference between successive test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material, would in the long run, in the normal and correct operation of the test method, exceed the value 3 g/tool only in one case in twenty. 6.1.2 Reproducibility--The difference between two single and independent results, obtained by different operators,
This test method is under the jurisdiction of ASTM Committee !)-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee 1:)02.04 on Hydrocarbon Analysis. Current edition approved Aug. 15, 1992. Published October 1992. Originally published as D 2502 - 66 T. Last previous edition D 2502 - 82. 2 Hirschler, A. E., Journal of the lnstitnte of Petroleum, JIPEA, Vol 32, 1946, p. 133. 3 Annual B¢u~ko[ASTM Standards, Vol 05.01. 4 Available from ASTM Headquarters. Order PCN 12-425020-00.
361
(~ D 2502 accordance with RR:D02-1007, "Manual on Determining Precision Data for ASTM Methods on Petroleum Products and Lubricants. ''5
working in different laboratories on identical test material, would in the long run, in the normal and correct operation of the test method, exceed the value 25 g/mol only in one case in twenty. 6.2 BiasmSince there is no accepted reference material suitable for determining bias for this test method, no statement of bias can be made. 6.3 The precision for this test method was not obtained in
7.
Keywords 7.1 kinematic viscosity; molecular weight; petroleum oils; relative molecular mass 5 ,Immal Book oI'..ISTM Standards, Vol 05.03.
TABLE 1
Tabulation of H Function
Kinematic Viscosity, cSt, at 100*F (37.780C)
H 0
0.2
0.4
0.6
0,8
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39
-178 -67 -1 44 79 106 128 147 163 178 190 201 211 221 229 237 244 251 257 263 269 274 279 283 288 292 296 300 304 307 310 314 317 320 323 326 328 331
-151 -52 9 52 85 111 132 151 166 180 192 203 213 222 231 238 245 252 258 264 270 275 280 284 289 293 297 301 304 308 311 314 317 320 323 326 329 332
-126 -38 19 59 90 116 136 154 169 183 195 206 215 224 232 240 247 253 259 265 271 276 281 285 289 294 298 301 305 308 312 315 318 321 324 327 329 332
-104 -25 28 66 96 120 140 157 172 185 197 208 217 226 234 241 248 255 261 266 272 277 281 286 290 294 298 302 306 309 312 316 319 322 325 327 330 333
-85 -13 36 73 101 124 144 160 175 188 199 210 219 227 235 243 249 256 262 267 273 278 282 287 291 295 298 303 306 310 313 316 319 322 325 328 331 333
H
40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190
0
1
2
3
4
5
6
7
8
9
334 355 372 386 398 408 416 424 431 437 443 448 453 457 461 465
336 357 374 387 399 409 417 425 432 438 443 449 453 458 462 466
339 359 375 388 400 410 418 425 432 438 444 449 454 458 462 466
341 361 377 390 401 410 419 426 433 439 444 450 454 459 463 466
343 363 378 391 402 411 420 427 433 439 445 450 455 459 463 467
345 364 380 392 403 412 420 428 434 440 446 450 455 460 463 467
347 366 381 393 404 413 421 428 435 441 446 451 456 460 464 468
349 368 382 394 405 414 422 429 435 441 447 451 456 460 464 468
352 369 384 395 406 415 423 430 436 442 447 452 456 461 465 468
354 371 385 397 407 415 423 430 437 442 448 452 457 461 465 469
362
~') D 2502 TABLE 1
Continued
Kinematic Viscosity, cSt at 100°F (37.78°C)
0
10
20
30
40
50
60
70
80
90
200 300 400 500 600 700 800 900
469 497 515 529 540 549 557 563
473 499 517 530 541 550 557 564
476 501 518 531 542 551 558 565
479 503 520 533 543 551 559 565
482 505 521 534 544 552 559 566
485 507 523 535 545 553 560 566
487 509 524 536 546 554 561 567
490 511 525 537 547 554 562 567
492 512 527 538 547 555 562 568
495 514 528 539 548 556 663 569
0
100
200
300
400
500
600
700
800
900
569 605 625 638 648 656 663 668 673
574 608 626 639 649 657 664 669 674
578 610 628 640 650 658 664 670 674
583 612 629 641 651 658 665 670 675
587 614 631 642 652 659 665 671 675
591 616 632 643 652 660 666 671 676
594 618 633 644 653 660 666 671 676
597 620 634 645 654 661 667 672 677
600 621 636 646 655 662 667 672 677
603 623 637 647 656 662 668 673 677
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
678 705 720 731 739 745 750 755 759 762
681 707 722 732 739 746 751 755 759 762
684 709 723 732 740 746 751 756 759 763
688 711 724 733 741 747 752 756 760 763
691 712 725 734 74t 747 752 756 760 763
694 714 726 735 742 748 753 757 760 764
696 715 727 736 743 748 753 757 761 764
699 717 728 736 743 749 753 758 761 764
701 718 729 737 744 749 754 758 761 764
703 719 730 738 744 750 754 758 762 765
1 2 3 4 5 6 7 8 9
000 000 000 000 000 000 000 000 000
10 000 20 000 30 000 40 000 50 000 60 000 70 000 80 000 90 000 100 000
H
300 . , ~
400
500
600
RELATIVEMOLECULARMASS FIG. 1
Viscosity-Molecular Weight Chart
363
700
~t~) D 2502 The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reepproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at s meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
364
q~T~
Designation: D 2 5 0 3 - 92
An Amencan National Standard
Standard Test Method for Relative Molecular Mass (Molecular Weight) of Hydrocarbons by Thermoelectric Measurement of Vapor Pressure This standard is issued under the fixed designation D 2503; the number immediately following the designation indicates the year of original adoption or, in the ease of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (0 indicates an editorial change since the last revision or reapproval.
This Wst method has been approvedfor use by agencies of the Department oJ'De./ense. Consult the DoD huh,x ol Spec~ficatums and Standards for the specific year of issue which has been adopted by the Department of DeJense.
4. Apparatus 4. l Vapor Pressure Osmometer, with operating diagram. 2
1. Scope 1.1 This test method covers the determination of the average relative molecular mass (molecular weight) of hydrocarbon oils. It can be applied to petroleum fractions with molecular weights (relative molecular mass) up to 3000; however, the precision of the method has not been established above 800 molecular weight (relative molecular mass). The method should not be applied to oils having initial boiling points lower than 220"C. 1.2 Values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for information purposes only. 1.3 This standard does not purport to address all of the
5. Reagents and Materials 5.1 Purity of Reagents--Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available) Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 5.2 Solvents--Solvents that do not react with the sample must be used. Since many organic materials exhibit a tendency to associate or dissociate in solution, it is desirable to use polar solvents for polar samples and nonpolar solvents for nonpolar samples. The solvents listed have been found suitable for hydrocarbons and petroleum fractions. 5.2.1 Benzene
safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, 5.2.1, 5.2.3, and 5.2.3.
2. Summary of Test Method 2.1 A weighed portion of the sample is dissolved in a known quantity of appropriate solvent. A drop of this solution and a drop of solvent are suspended, side by side, on separate thermistors in a closed chamber saturated with solvent vapor. Since the vapor pressure of the solution is lower than that of the solvent, solvent condenses on the sample drop and causes a temperature difference between the two drops. The resultant change in temperature is measured and used to determine the relative molecular mass (molecular weight) of the sample by reference to a previously prepared calibration curve.
NOTE l: Warning--Poison. Carcinogen. Harmful if swallowed. Extremely flammable.Vapors may cause flash fire. Vapor harmful, may be absorbed through skin. 5.2.2 Chloroform NOTE 2: Warning--May be fatal if swallowed. Harmful if inhaled. May produce toxic vapors if burned. 5.2.3 l,l,l- Trichloroethane NOTE 3: WarningIHarmful if inhaled. High concentrations may cause unconsciousnessor death. Contact may cause skin irritation and dermatitis. NOTE 4IThe precision data given in 10.1 and 10.2 will apply only when benzene is used as the solvent. There is also some evidence that determinations on the same oil sample carried out in different solvents will produce results that differ somewhat in absolute magnitude of apparent molecularweight (relative molecular mass).
3. Significance and Use 3.1 Relative molecular mass (molecular weight) is a fundamental physical constant that can be used in conjunction with other physical properties to characterize pure hydrocarbons and their mixtures. 3.2 A knowledge of the relative molecular mass (molecular weight ) is required for the application of a number of correlative methods that are useful in determining the gross composition of the heavier fractions of petroleum.
5.3 Reference Standards--A calibration curve must be constructed for each new lot of solvent using a pure compound whose relative molecular mass (molecular weight) is 2 A vapor pressure osmomcter is available from H. Knauer and Co., Berlin, West Germany. The manufacture ofthe Mechrolab instrument previously referred to in this footnote has been discontinued. I Iowcver, .,,onle models zn:ly I'u.,;.Ivall-'d~l¢ from stocks on hand at laboratory supply houses, or as used equipment from laboratory instrument exchanges. 3 "Reagent Chemicals, American Chemical Society Specifications," Am. Chemical Soc., Washington, IX:. For suggestions on the testing of reagents not listed by the American Chemical Society, see "Analar Standards for Laboratory U.K. Chemicals," BDH Ltd., Poole, Dorset, and the "United States Pharmacopeia."
J This test method is under the jurisdiction of ASTM Committee 1:)-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.04 on Hydrocarbon Analysis. Current edition approved Aug. 15, 1992. Published October 1992. Originally published as D 2503 - 66T. Last previous edition D 2503 - 82 (1987)~t.
365
~) D 2503 TABLE 1 Precision Data (Benzene Solvent)
accurately known. Compounds that have been used successfully include benzil (210.2), n-octadecane (254.5), and squalane (422.8). 6. Sampling 6.1 The sample must be completely soluble in the selected solvent at concentrations of at least 0.10 M, and it must not have an appreciable vapor pressure at the test temperature. 7. Preparation and Calibration of Apparatus 7.1 Prepare standard 0.01, 0.02, 0.04, 0.06, 0.08, and 0.1 M solutions of the calibrating compound in the solvent selected. 7.2 Remove the upper sample chamber assembly. Rinse the solvent cap with the solvent to be used. Install a vapor wick in the cup and fill with solvent to the bottom of the notches in the inner wick. Place the cup in the chamber base recess, align the vapor wick openings with the viewing tubes, andreplace 'the upper assembly. Take care that the guide pins properly engage matching holes in the thermal block and that the matching surfaces of the base and block are clean. Be careful not to allow the thermistor beads to touch the cup or wicks as they may be bent out of alignment. Turn on the thermostat and allow the temperature of the sample chamber to reach equilibrium at 37"C. NOTE 5 - - I f the block is at room temperature, 2 to 3 h will be
required. To avoid such delay, it is desirable to always leave the thermostat switchin the "on" position, if the chamber is at equilibrium and is opened briefly, 30 to 45 rain will generallybe required before temperature stabilization is regained. The exchange or refilling of syringesdoes not necessitateany waitingperiod. 7.3 Thoroughly rinse all syringes with the solvent being used and allow to dry. 7.4 Fill the syringes from guide tubes "5" and "6" with the solvent. Fill the syringes for guide tubes "1" through "4" with the standard solutions in order of increasing concentration. 7.5 Insert the syringes into the thermal block, keeping the guide pins pointed away from the probe. Turn on the "Null Detector" switch (Note 6). Set the sensitivity control to sufficient gain so that a 1.0-fi shift in the "Dekastat" produces one major division shift of the meter needle. NOTE 6--No measurements should be attempted until the "Null Detector" switchhas been on for at least 30 min. 7.6 Turn on the "Bridge" switch and turn the "T-AT" switch to "T". Approximately zero the meter with the "T" potentiometer and observe the drift of the needle. If the solvent chamber is at equilibrium, the needle should not drift more than 1 to 2 mm during one complete heating cycle; a steady drift to the right indicates that the chamber is still warming up; if "T" is stable, switch the selector to the "AT" position. 7.7 While observing the thermistors in the viewing mirror, lower the syringe in position "5", by rotating the knurled collar of the holder fully clockwise. With the end of the needle directly above the reference thermistor, turn the feed screw and rinse the thermistor with about 4 drops of solvent. Finally, deposit a drop of solvent on the ther~aistor bead and raise the syringe by rotating the knufled collar in a counterclockwise direction. Rinse the sample thermistor with solvent from syringe "6" and apply a drop approximately the size of the drop on the reference thermistor. Depress the zero 366
Relative Molecular Mass (Molecular Weight) Range
Repeatability, g/mot
Reproducibility. g/tool
245 to 399 400 to 599 600 to 800
5 12 30
14 32 94
button, and zero the meter with the "Zero" control. Set the decade resistance to zero, and balance the bridge using the "Balance" control. Repeat the balancing of the bridge with fresh drops of solvent on each thermistor to assure a good reference zero. 7.8 Lower syringe " l " and rinse the sample thermistor with 3 to 4 drops of solution, finally applying one drop to the bead. Start the stop watch. Center the meter by means of the decade dials and take readings at l-min intervals until two successive readings do not differ by more than 0.01 ohm. Record the AR value, estimating to the nearest 0.01 fl from the meter. Record the time required to reach this steady state, and use this time for all subsequent readings for thc solvent used. 7.9 Upon completing each series of sample readings, rinse the sample thermistor with solvent, deposit a drop, and recheck the zero point. The meter should reproduce the original indication within 0.5 mm. If the needle shows a negative deflection, the sample thermistor should be rinsed again. If it shows a positive deflection, the drop on the reference thermistor should be replaced. 7.10 Plot the AR values for each concentration of standard against the molarity of the standard for the solvent used. NOTE 7--The calibrationmust be repeated for each of the solventsto be employedand separateworkingcurvesconstructed. Recalibrationis necessaryeach time a new batch of solvent is put into use.
8. Procedure 8.1 Select the solvent to be used and fill the solvent cup as described in 7.2. Weigh into a 25-mL volumetric flask the amount of sample suggested in the following table (Note 5): Estimated Relative Molecular Mass
Sample Size, g
Less than 200 200 to 500 500 to 700 700 to 1000
0.3 0.3 to 0.6 0.6 to 0.9 0.9 to 1.3
Record the weight to the nearest 0.1 mg and dilute to volume with solvent. NOTE 8 - - I f the amount ofsample is limited, weigh the sample into a 5 or I-mL volumetric flask, using one-fifth or one twenty-fifth respectively of the amount indicated in the table. Weighto the nearest 0.001
mg usinga microbalance. 8.2 Fill syringes "5" and "6" with solvent and fill one of the remaining syringes with the sample solution. With the sample chamber at thermal equilibrium, balance the bridge to establish the reference zero as described in 7.6 and 7.7. 8.3 Rinse the sample thermistor with 3 or 4 drops of the sample solution and deposit 1 drop on the thermistor. Start the stop watch. Center the meter with the decade dials and record AR at the time interval determined during the standardization for the solvent being employed (7.8). When
~) D 2503 running a series of samples, check the zero point frequently as described in 7.9. 8.4 Using the appropriate calibration curve, obtain the molarity corresponding to the observed AR value.
apparatus under constant operating conditions on identical test material, would in the long run, in the normal and correct operation of the test method, exceed the values shown in Table l only in one case in twenty. I l.l.2 ReproducibilitymThe difference between two single and independent results, obtained by different operatots, working in different laboratories on identical test material, would in the long run, in the normal and correct operation of the test method, exceed the values shown in Table l only in one case in twenty. I I. 1.3 The precision was not obtained in accordance with Committee D-2 Research Report RR-D-2-1007, "Manual on Determining Precision Data for ASTM Methods on Petroleum Products and Lubricants.''4 11.3 Bias--Bias for this method has not been determined.
9. Calculation 9.1 Calculate the relative molecular mass (molecular weight) of the sample as follows: Relative Molecular Mass (molecularweight) = c/m where: c = concentration of sample solution, g/L and m = molarity of solution, as determined in 8.4.
10. Report 10.1 Report the result to the nearest whole number.
12. Kcywords 12.1 hydrocarbons; molecular weight; osmometer; relative molecular mass; thermoelectric measurement; vapor pressure
11. Precision and Bias 11.1 Precision--The precision of this test method as obtained by statistical examination of interlaboratory test results is as follows: I1.1.1 Repeatability--The difference between successive test results obtained by the same operator with the same
4 Annual Book of ASTM Standards, Vol 05,03.
The American Society for Testing and Materials takes no position respectmg the vafldity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the vafidity of any such patent rights, and the risk of infringement of such rights, ere entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and ff not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
367
Designation: D 2504-88 (Reapproved 1993)el
An American National Standard
Standard Test Method for Noncondensable Gases in C 2 and Lighter Hydrocarbon Products by Gas Chromatography 1 This standard is issued under the fixed designation D 2504; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reappmval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval. o NoTE--Keywords were added editorially in October 1993.
1. Scope 1.1 This test method covers the determination of hydrogen, nitrogen, oxygen, and carbon monoxide in the parts per million volume (ppmv) range in C2 and lighter hydrocarbon products. This test method should be applicable to light hydrocarbons other than ethylene, but the test program did not include them. 1.2 The values stated in acceptable metric units are to be regarded as the standard. The values in parentheses are for information only. 1.3 This standard does not purport to address all of the
safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For some specific hazard statements, see Notes 3, 4, and 5. 2. Referenced Documents
2.1 A S T M Standards: D2505 Test Method for Ethylene, Other Hydrocarbons, and Carbon Dioxide In High-Purity Ethylene by Gas Chromatography 2 E 260 Practice for Packed Column Gas Chromatography 3 F 307 Practice for Sampling Pressurized Gas for Gas Analysis 4 2.2 Other Standard." 5 Compressed Gas Association Booklets G-4 and G-4.1 on the use of oxygen. 3. Summary of Test Method 3.1 The sample is separated in a gas-solid chromatographic system using molecular sieves as the solid adsorbent. The concentration of the gases to be determined is calculated from the recorded peak heights or peak areas. Argon can be used as a cartier gas for the determination of hydrogen in concentrations below 100 ppmv. Argon, if present in the sample, interferes with oxygen determination. J This test method is under the jurisdiction of ASTM Committee I)-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.D on Hydrocarbons for Chemical and Special Uses. Current edition approved Oct. 31, 1988. Published December 1988. Originally published as D 2504 - 66 T. Last previous edition D 2504 - 83~1. 2 Annual Book of ASTM Standards, Vol 05.01. 3 Annual Book of ASTM Standards, Vol 14.01. 4 Annual Book of ASTM Standards, Vol 10.05. 5 Available from Compressed Gas Association, 1253 Jefferson Davis Highway, Arlington, VA, 22202.
4. Significance and Use 4.1 The presence of trace amounts of hydrogen, oxygen, and carbon monoxide can have deleterious effects in certain processes using hydrocarbon products as feed stock. This test method is suitable for setting specifications, for use as an internal quality control tool and for use in development or research work. 5. Apparatus 5.1 Chromatograph--Any chromatographic instrument having either a thermal conductivity or ionization detector with an overall sensitivity sufficient to detect 2 ppmv or less of the compounds listed in the scope, with a peak height of at least 2 mm without loss of resolution. 5.2 Detectors--Thermal Conductivity--If a methanation reactor is used, a flame ionization detector is also required. To determine carbon monoxide with a flame ionization detector, a methanation reactor must be inserted between the column and the detector and hydrogen added as a reduction gas. Details on the preparation and use of the reactor are given in Appendix X I. 5.3 Constant-Volume Gas Sampling Valve. 5.4 Column--Any column or set of columns that is capable of resolving the components listed in the scope can be used. Copper, stainless steel, or aluminum tubing may be used. The columns chosen must afford a resolution such that the depth of the valleys ahead of the trace peak is no less than 50 % of the trace peak height. 5.5 Recorder--A recorder with a full-scale response of 2 s or less and a maximum rate of noise of :t:0.3 % of full scale. 5.6 Oven--The oven used for activating molecular sieves must be maintained at 260 to 288"C (500 to 550"F) and should be designed so that the gases may be displaced continuously by a stream of inert gas. The oven may be a thermostated piece of l-in. pipe about 0.3m (1 ft.) in length. Electrical heating tapes or other means may be used for heating provided the heat is distributed uniformly. NOTE i--The use of copper tubing is not recommended with samples containing acetylene as this could lead to the formation of potentially explosivecopper acetylide. 6. Reagents and Materials 6.1 Molecular Sieves, 5A, 13A, or 13X--Any mesh sizes can be used so long as sensitivity and resolution are maintained (see Note 2). If a 40 to 60-mesh sieve size is desired, but is not available, it may be prepared as described in 8.1.
368
~
D 2504
6.2 CoconutCharcoal, 30 to 60-mesh sieve size (optional). NOTE 2--Columns that have been found to give the desired separation include a l-m by 3.175-ram outside diameter column of 100 to 120 mesh 5A molecular sieve, a 3-m by 6.35-mm outside diameter column of 40 to 60-mesh 5A sieve, and a 7.7-m by 6.35-mm outside diameter column with 13A or 13X sieve in the first 7.4 m and charcoal in the 0.3
is always preferable not to dilute the first sample. NOTE 8--Synthetic standard samples should be prepared as described in Test Method D 2505.
9.3 Inject a known volume of one of the standard samples, using a minimum of 1 mL for detecting 2 ppmv.
m.
NOTE 9--Use of a reverse-flowarrangement will facilitate removal of heavier gases and decrease the elapsed time of analysis.
6.3 Gasesfor Calibration--Pure or research grade hydrogen, oxygen, nitrogen, and carbon monoxide will be needed to prepare synthetic standard samples as described in Test Method D 2505. (Warning--See Notes 4 and 5.) Certified calibration blends are commercially available from numerous sources and can be used as the synthetic standard samples. NOTE 3: Warning--Flammable gases. Hazardous pressure. See Annexes AI.I through AI.5. NOTE 4: Warning--Flammable. Poison. Harmful if inhaled. Dangerous when exposed to flame. See Annex A 1.5. NOTE 5: Warning--Hazardous pressure. See Annex A I.2. 6.4 CarrierGases--Argon or helium. NOTE 6--Practices E 260 contains information that will be helpful to those using this test method.
9.4 Record all of the desired peaks on each of the synthetic blends prepared. 9.5 Prepare a chart for each compound, plotting the peak height of the compound or peak area of the compound against the concentration of the compounds in ppmv. The peak area can be determined by any method that meets the precision requirements of Section 12. Methods found to be acceptable include planimetering, integration (electronic or mechanical or computer processing), and triangulation. 10. Procedure
10.1 Connect the sample cylinder containing a gaseous sample to the gas sample valve with a metal tube and allow the sample to flow from the sample tube for about 1/2 min. at a rate of 70 to 100 mL/min. 10.2 Inject into the instrument the same volume of sample as used for calibration, (pressure of sample and calibration gas must be the same in the sample loop) and record the peak areas or peak heights desired.
7. Sampling 7.1 Samples shall be supplied to the laboratory in highpressure sample cylinders, obtained using the procedures described in Practice F 307 or similar methods. 8. Preparation of Apparatus
8.1 Chromatographic Column Packing--Crush in a porcelain mortar and sieve to 40 to 60-mesh size about 200 g of molecular sieves 5A in order to have enough for several columns. All work of preparing molecular sieves and packing columns with this material shall be done rapidly, preferably under a blanket of dry nitrogen in order to minimize moisture absorption. Heat the screened molecular sieves in an oven at 274 + 14"C (525 _+ 25"F) for 24 h purging with dry nitrogen at a rate of about 5 mL/min during this time. The nitrogen rate is not critical and can be measured by any convenient means such as an orifice meter, rotameter, manometer, etc. Do not use a wet test meter. 8.2 Chromatographic Column--Purge the metal tubing with dry nitrogen. Insert a small amount of glass wool in the end. Fill rapidly with the screened and activated molecular sieves, adding the latter in l-g increments. Vibrate the column, adding additional sieves during this period, if necessary, to fill. Insert a small amount of glass wool in the top. Bend the column in the shape required to fit the chromatographic instrument. Regenerate the column in the oven in the same manner as described in 8.1 whenever the oxygen is not completely separated from the nitrogen peak.
11. Calculation 11.1 From the peak height or area of the compound in the sample, determine the moles per million of the compound using the charts prepared in calibration. A typical characterization showing hydrogen, oxygen, and nitrogen in ethylene is presented in Fig. 1. 12. Precision and Bias
12.1 The precision of this test method as determined by statistical examination of interlaboratory results is as follows: 12.1.1 Repeatability--The difference between successive test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, and in the normal and correct operation of the test method, exceed the following values only in one case in twenty: Component Oxygen
Nitrogen Carbon Monoxide Hydrogen
Range, ppmv
Repeatability, ppmv
10-150 100-700 0-20 0-15
15 72 3 2
12.1.2 Reproducibility--The difference between two single and independent results obtained by different operators working in different laboratories on identical test material would, in the long run, and in the normal and correct operation of the test method, exceed the following values only in one case in twenty:
9. Calibration 9.1 Bring the equipment and column to equilibrium and maintain a constant carrier gas rate and temperature. NOTE 7--Carrier gas rates of 36 to 60 mL/min and temperatures of 50 to 60"C have been used successfully. 9.2 Prepare at least three synthetic standard samples containing the compounds to be determined over the range of concentration desired in the products to be analyzed, using the pure gases or the certified blend. For the preparation of the second, third, and following calibration samples it
Component Oxygen Nitrogen Carbon Monoxide Hydrogen
369
Range, ppmv 10-150 100-1000 0-20 0-15
Reproducibility, ppmv 155 875 7 8
~
D 2504
45.28
Z
04
40.26
35.
E3 C,J Q
SO. 2 i
25. i9
L
20. t7 0.00
,
I 2.00
,
I 4.0t
FIG. 1
,
1 E.0i
1
I 8.02
Typical Chromatogram
,
I t0.0S
,
1
t2.03
,
I
t4.04
!
i6.05
for H y d r o g e n , O x y g e n a n d Nitrogen
NOTE 10--The committee believes the methods for oxygen and nitrogen are better than the precision would indicate, and that the poor reproducibilityis attributable to the difficultyof excludingair from these samples. Precise results are heavily dependent upon extreme care in sampling and handling. The use of continuous analyzers is preferred, and is recommended whenever circumstances permit.
12.2 BiasmThe bias of the procedure in this test method has not yet been determined but it is now under consideration by the responsible committee. 13. Keywords 13.1 carbon dioxide; ethane; ethylene; gas chromatography; hydrocarbons; methane; nitrogen
ANNEX
(Mandatory Information) AI. PRECAUTIONARY S T A T E M E N T S
A1.2 Compressed Gases
AI.I Flammable Gas Keep away from heat, sparks, and open flame. Use with adequate ventilation. Never drop cylinder. Make sure cylinder is supported at all times. Keep cylinder out of sun and away from heat. Always use a pressure regulator. Release regulator tension before opening cylinder. Do not transfer cylinder contents to another cylinder. Do not mix gases in cylinder. Keep cylinder valve closed when not in use. Do not inhale. Do not enter storage areas unless adequately ventilated. Stand away from cylinder outlet when opening cylinder valve. Keep cylinder from corrosive environment. Do not use cylinder without label. Do not use dented or damaged cylinder. For technical use only. Do not inhale.
Keep container closed. Use with adequate ventilation. Do not enter storage areas unless adequately ventilated. Always use a pressure regulator. Release regulator tension before opening cylinder. Do not transfer to cylinder other than one in which gas is received. Do not mix gases in cylinders. Do not drop cylinder. Make sure cylinder is supported at all times. Stand away from cylinder outlet when opening cylinder valve. Keep cylinder out of sun and away from heat. Keep cylinder from corrosive environment. Do not use cylinder without label. Do not use dented or damaged cylinder. For technical use only. Do not use for inhalation purposes.
370
(@) D 2504 AI.3 Hydrogen Danger--Extremely flammable gas under pressure. Keep away from heat, spark, and open flame. Use with adequate ventilation. Never drop cylinder. Make sure cylinder is supported at all times. Keep cylinder out of sun and away from heat. Always use a pressure regulator. Release regulator tension before opening cylinder. Do not transfer cylinder contents to another cylinder. Do not mix gases in cylinder. Keep cylinder valve closed when not in use. Do not inhale. Do not enter storage areas unless adequately ventilated. Stand away from cylinder outlet when opening cylinder valve. Keep cylinder from corrosive environment.
before opening cylinder valve. All equipment and containers used must be suitable and recommended for oxygen service. Never attempt to transfer oxygen from cylinder in which it is received to any other cylinder. Do not mix gases in cylinders. Do not drop cylinder. Make sure cylinder is secured at all times. Keep cylinder valve closed when not in use. Stand away from outlet when opening cylinder valve. For technical use only. Do not use for inhalation purposes. Keep cylinder out of sun and away from heat. Keep cylinder from corrosive environment. Do not use cylinder without label. Do not use dented or damaged cylinders. See Compressed Gas Association booklets G-4 and G-4.1 for details of safe practice in the use of oxygen.
A1.4 Oxygen Keep oil and grease away. Do not use oil or grease on regulators, gauges or control equipment. Use only with equipment condition for oxygen service by carefully cleaning to remove oil, grease and other combustibles. Keep combustibles away from oxygen and eliminate ignition sources. Keep surfaces clean to prevent ignition or explosion, or both, on contact with oxygen. Always use a pressure regulator. Release regulator tension
A1.5 Carbon Monoxide Harmful or fatal if inhaled. Dangerous when exposed to flame. Keep away from heat, sparks, and open flame. Use with adequate ventilation. Use fume hood whenever possible. Avoid build-up of vapor and eliminate all sources of ignition, especially nonexplosion proof electrical apparatus and heaters. Avoid breathing.
371
(~ D 2504
APPENDIX
(Nonmandatory Information) X1. PREPARATION OF METHANATION REACTOR XI.I Scope X I.I.I This method describes the preparation of a methanation reactor to convert carbon monoxide and carbon dioxide to methane, which can then be determined using a flame ionization detector at levels less than 1 ppm.
sorb. Warm the mixture to 650C on a hot plate and evaporate the methanol with constant stirring, until the mixture appears dry. The resultant catalyst is subsequently reduced in the hydrogenation tube during instrument preparation.
X1.2 Significance and Use X 1.2.1 The use of a flame ionization detector to enhance the detection limits for carbon monoxide and carbon dioxide is made possible by conversion of these gases to methane.
X1.3 Apparatus XI.3.1 Tubing, 152.4 mm (6-in.) of 6.35 mm (l/4-in.) stainless steel. XI.3.2 Aluminum blockmlOI.6 by 152.4 by 15.8 mm (4-in. by 6-in. by %-in.) drilled to accept a I/4-in. tube snugly. XI.3.3 Cartridge heaterD175 W with variable autotransformer. X 1.3.4 Thermocouple sensorDchromel alumel. NOTE X l.l--Commercial instruments performingthe determination in compliancewith this procedure are available.
XI.4 Reagents and Materials X 1.4.1 Insulation. X 1.4.2 Harshaw methanation catalyst-Ni-104t, I00 to 120 mesh, or catalyst prepared as in XI.5. Xl.5 Catalyst Preparation X 1.5. I Hydrogenation catalyst: Prepare by weighing 20 +_ 0.1 g of nickel nitrate hexahydrate into a 100-mL beaker. Add 40 mL of methanol. Weigh 20 _ 0.1 g of Chromosorb "P" into an evaporating dish. After the nickel nitrate crystals have dissolved, slowly pour the solution over the Chromo-
X1.6 Procedure X 1.6.1 Using glass wool as a retainer, pack the 152.4 mm (6-in.) by 6.35 mm (l/4-in.) stainless tube 38.1 mm (1.5-in.) from either end with catalyst. Allowing 38. l mm (1.5-in.) of space at each end of the tube insures failure to produce a highly toxic compound, nickel-carbonyl. XI.6.2 The aluminum block should have three holes drilled in it. One hole should be drilled through the block, lengthwise, in the center of the end, 6.35 mm (l/4-in.) in diameter. Another hole should be drilled on either side of the center. Its dimensions should be 50.8 by 9.53 mm (2-in. by 0.375-in.) in diameter. This hole will accept the cartridge heater. The third hole should be 50.8 mm (2-in.) long and 3.18 mm (I/s-in.) in diameter and on the opposite side of center as the cartridge heater. This will accept the thermocouple sensor. X1.6.3 Place the packed tube through the block so that the ends extend equally from either end of the block. Place the cartridge heater in the block, wrap the system with insulation, and place the therrnocouple in the 3.18 mm (l/8-in.) hole. Use only stainless steel connectors and attach one end of the 6.35 mm (l/4-in.) packed tube to detector inlet. Attach the discharge end of the chromatographic column to the other end of the reactor through a tee connector. The tee is provided in order to introduce 30 mL/min, of hydrogen to the methanator. X 1.6.4 After setting the hydrogen flow, connect the heater to a variable autotransformer. The setting should be approximately 55. Allow the catalyst to condition for 24 h at 300oc. Normal operating temperature for the methanator should be 325 + 250C.
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reepproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
372
Designation:D2505-88 (Reapproved1993)
An American National Standard
Standard Test Method for Ethylene, Other Hydrocarbons, and Carbon Dioxide in High-Purity Ethylene by Gas Chromatography 1 This standard is issued under the fixed designation D 2505; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (E) indicates an editorial change since the last revision or reapproval. ~ NorE--Keywords were added editorially in October 1993.
phosphoramide (HMPA) column. Acetylene is determined by using, in series, a hexadecane column and a squalane column. Carbon dioxide is determined using a column packed with activated charcoal impregnated with a solution of silver nitrate in fl,B'-oxydipropionitrile. Columns other than those mentioned above may be satisfactory. (see 5.3.) Calibration data are obtained using standard samples containing the impurities, carbon dioxide, methane, and ethane in the range expected to be encountered. Calibration data for acetylene are obtained assuming that acetylene has the same peak area response on a weight basis as methane. The acetylene content in a sample is calculated on the basis of the ratio of peak area of the acetylene peak to the peak area of a known amount of methane. Calculations for carbon dioxide, methane, and ethane are carded out by the peak-height measurement method.
1. Scope I. 1 This test method covers the determination of carbon dioxide, methane, ethane, acetylene, and other hydrocarbons in high-purity ethylene. Hydrogen, nitrogen, oxygen, and carbon monoxide are determined in accordance with Test Method D 2504. The percent ethylene is obtained by subtracting the sum of the percentages of the hydrocarbon and nonhydrocarbon impurities from 100. The method is applicable over the range of impurities from I to 500 parts per million volume (ppmV). 1.2 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For some specific hazard statements, see Notes 8 through 9. 1.3 The values stated in acceptable metric units are to be regarded as the standard. The values in parentheses are for information only. 2. Referenced Documents
2.1 A S T M Standards: D 2504 Test Method for Noncondensable Gases in C2 and Lighter Hydrocarbon Products by Gas Chromatography 2 D4051 Practice for Preparation of Low-Pressure Gas Blends 3 E 260 Practice for Packed Column Gas Chromatography 4 F 307 Practice for Sampling Pressurized Gas for Gas Analysis5 3. Summary of Test Method 3.1 The sample is separated in a gas chromatograph system utilizing four different packed chromatographic columns with helium as the carrier gas. Methane and ethane are determined by using a silica gel column. Propylene and heavier hydrocarbons are determined using a hexamethyl' This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.D on Hydrocarbons for Chemical and Special Uses. Current edition approved Oct. 31, 1988. Published December 1988. Originally published as D 2505 - 66 T. Last previous edition D 2505 - 83. 2 Annual Book of ASTM Standards, Vol 05.01. 3 Annual Book of ASTM Standards, Vol 05.02. 4 Annual Book of ASTM Standards, Vol 14.01. s Annual Book of ASTM Standards, Vol 10.05.
373
4. Significance and Use 4.1 High-purity ethylene is required as a feedstock for some manufacturing processes, and the presence of trace amounts of carbon dioxide and some hydrocarbons can have deleterious effects. This method is suitable for setting specifications, for use as an internal quality control tool and for use in development or research work. 5. Apparatus 5.1 Any chromatographic instrument with an overall sensitivity sufficient to detect 2 ppmV or less of the compounds listed with a peak height of at least 2 ram without loss of resolution. 5.2 Detectors--Thermal Conductivity--If a methanation reactor is used, a flame ionization detector is also required. To determine carbon dioxide with a flame ionization detector, a methanation reactor must be inserted between the column and the detector and hydrogen added as a reduction gas (see Test Method D 2504, Appendix X l). 5.3 Column--Any column or set of columns can be used that separates carbon dioxide, methane, acetylene and Ca and heavier compounds. There may be tailing of the ethylene peak but do not use any condition such that the depth of the valleys ahead of the trace peak is less than 50 % of the trace peak height. (See Fig. 3 for example.) 5.4 Recorder--A recorder with a full-scale response of 2 s or less and a maximum rate of noise of __.0.3 % of full scale. 5.5 Gas-Blending ApparatusmA typical gas-blending apparatus is shown in Fig. 1. A high-pressure manifold equipped with a gage capable of accurately measuring eth-
~@) D 2505 6.7 Acetone. NOTE 6--Extremely Flammable. See Annex A 1.1. 6.8 Gases for Calibration~Pure or research grade carbon dioxide, methane, ethane, acetylene, ethylene, propane, and propylene. Certified calibration blends are commercially available from numerous sources and may be used. NOTE 7: Warning--Flammable Gases, Hazardous Pressure. See Annexes AI.2 and AI.3.
glend C y l i n d e r
Pressure Gau'Je
6.9 Methanol. NOTE 8: W a r n l n g m F l a m m a b l e . Vapor Harmful. See A n n e x AI.4.
To Vacuum P.mp
NOTE 9--The use of copper tubing is not recommended with samples containing acetylene as this could lead to the formation of potentially explosivecopper acetylide.
To pressure regulated source of Ethvlene
~snometer
revel inq
7. Sampling 7.1 Samples should be supplied to the laboratory in high pressure sample cylinders, obtained using the procedures described in Practice F 307, or similar methods.
~ulb
FIG. 1
Gas-Blending Manifold
8. Preparation of Apparatus 8.I Silica Gel Column--Dry the silicagel in an oven at
ylene pressures up to 3.4 MN/m 2 gage (500 psig) is required. Other types of gas-blending equipment, such as described in Practice D 405 l, can be used. NoT~. I--ASTM Practices E 260, contains information that will be helpful to those using this method. 6. Reagents and Materials 6.1 Copper or Aluminum, or Stainless Steel Tubing, 6.4-ram (I/4-in.) outside diameter, and nylon tubing, 3.2mm (m/s-in.) outside diameter. 6.2 Solid Supports--Crushed firebrick or calcined diatomaceous earth, such as Chromosorb p,6 35 to 80-mesh and 80 to 100-mesh. Other supporting materials or mesh sieves can be satisfactory. 6.3 Active Solids~Activated carbon, 30 to 40-mesh, 7 silica gel, 100 to 200-mesh. s Other sizes may be satisfactory. 6.4 Liquid Phases--Hexamethylphosphoramide (HMPA9), hexadecane. 9 Squalene, 9 silver nitrate, and #,/V-oxydipropionitrile) ° Other liquid phases may be satisfactory. NOTE 2: Warning--Combustible solvents. See Annex AI.7. NOTE 3: Warning--HMPA may be harmful if inhaled. Causes irritation. A potential carcinogen (lungs). See Annex AI.5. 6.5 Helium. NOTE 4: Warning--Compressed Gas, Hazardous Pressure. See Annex A !.2. 6.6 Hydrogen. NOTE 5: Warning--Flammable Gas, Hazardous Pressure. See Annex AI.6. 6 Available from the Celite Division, Johns Mansville Co., New York, NY. A fraction sieved in the laboratory to 30 to 40 mesh from medium activity charcoal, 20 to 60 mesh, sold by Central Scientific Co., 1700 Irving Park Road, Chicago, IL 60613, has been found satisfactory for this purpose. s Silica gel Code 923 available from the Davison Chemical Co., Baltimore, Md. 21203, has been found satisfactory for this purpose. 9 Available from the Fisher Scientific Co., St. Louis, MO. io ~,/V-oxydipropionitrile, sold by Distillation Products Industries, Division of Eastman Kodak Co., Rochester, NY, has been found to be satisfactory.
374
204"C (400*F) for 3 h, cool in a desiccator, and store in screw-cap bottles.Pour the activated silicagel into a 0.9-rn (3-ft)length of 6.4-ram (t/4-in.)outside diameter copper or aluminum tubing plugged with glasswool at one end. Tap or vibratethe tube while adding the silicagel to ensure uniform packing and plug the top end with glass wool. Shape the column to fitinto the chromatograph. 8.2 Silver Nitrate--B,/3'-Oxydipropionitrile--Activated Carbon Column--Weigh I0 g of #,#'-oxydipropionitrileinto a brown 125-mL (4-oz) bottle. Add 5 g of silver nitrate (AgNO3) crystals.With occasionalshaking, dissolveas much AgNO3 as possible,and allow the bottleto stand overnightto ensure saturation. Prepare this solution fresh, as required. Without disturbing the crystalsat the bottom of the bottle, weigh 2.5 g of supernatant AgNO3 solution into a 250-mL beaker and add 50 m L of methanol. While stirringthis mixture, slowly add 22.5 g of activated carbon. Place the beaker on a steam bath to evaporate the methanoL When the impregnated activatedcarbon appears to be dry, remove the beaker from the steam bath and finishdrying in an oven at I00 to 110*C for 2 h. Plug one end ofa 4-ft(l.2-m) length of 6.4-ram (V4-in.)outsidediameter aluminum or stainlesssteel tubing with glass wool. Hold the tubing verticallywith the plugged end down and pour freshlydried column packing into it,vibratingthe column during fillingto ensure uniform packing. Plug the top end with glass wool and shape the tubing so that it may be mounted conveniently in the chromatograph. 8.3 Hexamethylphosphoramide Column (HMPA)mDry the 35 to 80-mesh inert support at 204"C (400*F). Weigh 75 g into a wide-mouth 500-mL (16-oz) bottle. Add 15 g of H M P A to the inert support and shake and rollthe mixture until the support appears to be uniformly wet with the HMPA. Pour the packing into a 6-m (20-ft) length of 6.4-ram (V4-in.) outside diameter copper of aluminum tubing plugged at one end with glass wool. Vibrate the tubing while filling to ensure more uniform packing. Plug the top end of the column with glass wool and shape the column to fit into the chromatograph.
~
D 2505
Suggested Composition of a Concentrate of Impurities Used in Preparing Standard Mixtures for Calibration Purposes
with high-purity ethylene in a ratio of approximately 1:4000. This can be done by adding the calculated amount of the concentrate and high purity ethylene to an evacuated cyclinder using the gas-blending apparatus (Fig. l). Use a source of high-pressure, high-purity ethylene equipped with a needle valve and a pressure gage capable of accurately measuring the pressure of the blend as the ethylene is added to the cylinder containing the concentrate. Add the calculated amount of ethylene; warm one end of the cylinder to ensure mixing of the blend. Allow the temperature to reach equilibrium before recording the final pressure on the cylinder. Prepare at least three calibration samples containing the compounds to be determined over the range of concentration desired in the products to be analyzed.
TABLE 1
Component
Percent
Carbon dioxide Methane Ethane Propylene
10 45 25 20
8.4 Hexadecane-Squalane Column--Dissolve 30 g of hexadecane into approximately 100 mL of acetone. Add 70 g of 80 to 100-mesh inert support. Mix thoroughly and pour the mixture into an open pan for drying. The slurry should be stirred during drying to ensure uniform distribution. When the acetone has evaporated, add a portion of the packing to a 7-m (25-ft) length of 3.2-ram 0/a-in.) outside diameter nylon tubing which has been plugged at one end with glass wool. Vibrate the column while filling to ensure more uniform packing. Fill the column with packing to only 4 m (15 ft) of the length of the column. Fill the remainder of the column with squalane packing prepared in the same manner as the hexadecane packing. Plug the open end of the tubing with glass wool and shape the column to fit into the chromatograph with the hexadecane portion of the column at the front end of the column. The column shall be purged under test conditions (no sample added) until a constant baseline is obtained.
NOTE 11: Precaution--As a safety precaution, use a manifold and fittings such as valves and gages that will withstand the pressure encountered. 9.2 Calculation of Composition of Standard Mixtures-Calculate the exact ratio of the concentrate dilution with ethylene by correcting the pressure of the ethylene added for the compressibility of ethylene (Table 2). Multiply the dilution ratio or factor by the percentage of each component present in the original concentrate (Table l). These calculations give the amount of each component that has been added to the high-purity ethylene blend stock. The actual composition of the final blend must be ascertained by making corrections for the impurities present in the highpurity ethylene used for the blend stock. The amount of correction is determined by making chromatograph runs on the high-purity ethylene and measuring the peak heights of the impurities. These peak heights will be used in adjusting the calibration factors described in 9.3. Since peak height is very sensitive to changes in conditions, it is extremely important in correlating peak heights obtained in making calibrations, calibration adjustments, and final impurity determinations that these values be obtained under the same GLC column operating conditions in all cases. 9.3 Determination of Calibration Factors--Chromatograph the standard blend and the high-purity ethylene blend stock by each of the procedures given in Section 10. 9.3.1 Calculate calibration factors for carbon dioxide, methane, ethane, propylene, and heavier hydrocarbons as follows: F = C/(S - B) (1)
NOTE 10--Columnsmade with liquid phases listed above were used satisfactorilyin cooperativework. Other columns may be used (see 5.3). 9. Calibration 9.1 Preparation of Standard Mixtures." 9.1.1 Preparation of Concentrate--Prepare a concentrate of the impurities expected to be encountered. A certified calibration blend containing the expected impurities can be obtained and used as the concentrate. An example of a satisfactory concentrate is given in Table 1. The concentrate can be prepared using the gas blending manifold as shown in Fig. 1 or using a similar apparatus as follows: Evacuate the apparatus and add the components in the order of increasing vapor pressure; that is, propylene, carbon dioxide, ethane and methane. Record the increase in pressure on the manometer as each component is added. Close the reservoir and evacuate the manometer after each addition. 9.1.2 Dilution of Concentrate--Dilute the concentrate
TABLE 2 Supercompressibility of Ethylene NOTE--The trace component, A, in parts per million volume of finished blend, is determined as follows: A = [(1 000 000 x Z b x
P=)/(Z= x
P,)] + B
(2)
where: Z a = value of Z for observed partial pressure and temperature of the trace component added, P= = partial pressure of trace component, psia (ram Hg x 0.01934), Zb = appropriate value of Z for final observed temperature and pressure of ethylene blend, PI = final observed pressure (psia) at observed temperature, and B = concentration, mols per million of trace component present in diluent ethylene. For synthetic pressures below 200 psia (1380 kN/m2), Z usage is not significant. Pressure, psia (kN/m 2
Values of Z
absolute)
15*C
20oc
25°C
30oC
350C
40oC
15 (103) 100 (690) 200 (1380) 300 (2068)
0.98 0.95 0.90 0.85
0.99 0.96 0.91 0.86
0.99 0.96 0.92 0.87
0.99 0.96 0.92 0.88
0.99 0.96 0.92 0.89
0.99 0.97 0.93 0.89
375
~ TABLE 3 Methane and Ethane Column packing
silica gel
Column dimensions
0.9 m (3 ft) by 6.4 mm (,/, in.)
Sample volume Carder gas
D 2505 Operating Conditions
Carbon Dioxide
Propylene and Heavier
AgNOs-oxydipropionitdle on support 1.2 m (4 ft) by 6.4 mm (V4 in.)
Acetylene
HMPA on support
hexadecane-squelane on support
6 m (20 ft) by 6.4 mm (V4 in.)
6 m (25 ft) by 3.2 mm (Vs in.)
1 mL
25 mL
1 mL
0.25 mL
helium 20 Ib
helium 10 Ib
helium
Carrier pressure
helium 20 Ib
Temperature
50oC
35°C
30oC
ambient
Detector
thermal conductivity
thermal conductivity
thermal cooductlvity
hydrogen flame ionization
where: F = mol percent per unit of peak height, C = concentration of component added to the high-purity ethylene blend stock, tool %, S = m m peak height of component in standard mixture, and B = mm peak height of component in high-purity ethylene blend stock, mm. 9.3.2 Calculate calibration factor for acetylene as follows: Fa C/(Sa - Ba) (3) where: Fa = weight percent per unit area, C = concentration of methane added to the high-purity ethylene blend stock in weight percent, Sa = area of methane peak in standard mixture, and Ba = area of methane peak in high-purity ethylene blend stock.
mum attenuation or g r e a t e s t sensitivity for maximum peak height. Figure 2 shows a typical chromatogram obtained with the procedure and operating conditions as outlined. Measure the height of each peak from the baseline in millimetres. Both peak height and peak area need to be measured for methane since the area will be used for preparation of an acetylene calibration curve. 10.2 Carbon Dioxide--Typical operating conditions for the analysis for carbon dioxide are given in Table 3. Flush the sample to be analyzed through the gas sample valve on the chromatograph until all extraneous vapor has been purged from the sample loop. Turn the gas valve to introduce the sample into the carrier gas stream. Record the carbon dioxide peak at the greatest sensitivity for maximum peak height. Measure the height of each peak from the baseline in millimetres. NOTE 12--T he elution order for this column is as follows:
:
Material
Approximate Time, rain
Air Methane Carbondioxide
10. Procedure 10.1 Methane and Ethane--Typical operating conditions for the analyses for methane and ethane are summarized in Table 3. Slowly flush the sample to be analyzed through the gas sample valve on the chromatograph until all extraneous vapor has been purged from the sample loop. Turn the gas valve to introduce the sample into the carrier gas stream. Record the deflection of each component peak at the mini-
2 3 7
Ethylene
1I
10.3 Propylene and Heavier--Typical operating conditions for the procedure for propylene and heavier components are given in Table 3. Flush the sample to be analyzed through the gas sample valve on the chromatograph until all the extraneous vapor has been purged from the sample loop.
Propylene
> >
2
m
w
- c
0
FIG. 2
1
2
m
3
LI
S
g
i
~
~
I 1
I~
Typical Chromatogram for Air, Methane, and Ethane
FIG. 3
376
I
,
I
I
I
I
I
I
I
2 3 u 5 6 7 8 9 lO Typical Chromatogram for Propylene
~)
D 2505
Turn the gas valve to introduce the sample into the carrier stream. Record the peaks of each component at maximum sensitivity for maximum peak height. Figure 3 shows a typical chromatograph obtained with the procedure and conditions described. Measure the height of each peak from the baseline as formed by the tailing of the ethylene peak. 10.4 Acetylene--Typical operating conditions for the analysis for acetylene are given in Table 3. Flush the sample to be analyzed through the gas sample valve on the chromatograph until all extraneous vapor has been purged from the sample loop. Operate the gas valve to introduce the sample into the carrier gas stream. Measure the peak areas of the methane and acetylene peaks. Figure 4 shows a typical chromatograph obtained with the procedure and conditions outlined.
where: C = concentration of component, mol %, D ffi peak height of the component, mm, and F ffi calibration factor of component as determined in 11.3.1. 11.2 Acetylene--Calculate the tool percent of acetylene in the sample as follows: C ffi A x Fax (28/26) (5) where: C = concentration of acetylene, tool %, A ffi area of the acetylene peak, and Fa ffi area calibration factor as determined in 6.3.2. 11.3 Ethylene--Calculate the tool percent of ethylene in the sample by adding the concentration of all impurities and subtract from 100.
l l . Calculation 11.1 Carbon Dioxide, Methane, Ethane, Propylene, and HeaviermCalculate the mol percent of each component present in the sample as follows: C-- D x F (4)
12. Precision and Bias
12.1 The precision of this test method as determined by statistical examination ofinterlaboratory results is as follows: 12.1.1 Repeatability--The difference between successive test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, and in the normal and correct operation of the test method, exceed the following values only in one case in twenty: Component Ethylene Methane Ethane
Propylene Propane
Acetylene Carbon dioxide
Range 99.80-99.99 mol % 1-150 ppmV 1-1500 ppmV 1-15 ppmV 1-15 ppmV 1-20 ppmV 1-10 ppmV
Repeatability 0.006 tool % 3 ppmV 43 ppmV 3 ppmV 2 ppmV I ppmV I ppmV
12.1.2 Reproducibility----The difference between two single and independent results, obtained by different operators working in different laboratories on identical test material would, in the long run, and in the normal and correct operation of the test method, exceed the following values only in one case in twenty: Component Ethylene Methane
Ethane Ethane
Propylene Propane Acetylene Carbon dioxide
Range 99.80-99.99 tool % 0- i 50 ppmV 0-500 ppmV 500-1500 ppmV 0-15 ppmV 0-15 ppmV 0-20 ppmV 0-10 ppmV
Reproducibility 0.1 mol % 34 ppmV 72 ppmV 290 ppmV 11 ppmV 7 ppmV 6 ppmV 4 ppmV
12.2 B/as--The bias of the procedure in this test method has not yet been determined but is now under consideration by the responsible subcommittee. HINUTES
I
0
I
1
I
2
I
3
I
13. Keywords 13.1 carbon dioxide; ethane; ethylene; gas chromatography; hydrocarbons; methane
q
FIG. 4 TypicalChrornatogramfor Acetylene as a Trace Impurity in Ethylene
377
~) D 2505
ANNEX
(Mandatory Information) A1. PRECAUTIONARY STATEMENTS
AI.I Acetone
Do not use cylinder without label. Do not use dented or damaged cylinder. For technical use only. Do not inhale.
Keep away from heat, sparks, and open flame. Keep container closed. Use with adequate ventilation. Vapors may spread long distances and ignite explosively. Avoid build-up of vapors and eliminate all sources of ignition, especially non-explosion proof electrical apparatus and heaters. Avoid prolonged breathing of vapor or spray mist. Avoid contact with eyes and skin.
A1.4 Methanol May be fatal or cause blindness if swallowed or inhaled. Cannot be made non-poisonous. Keep away from heat, sparks, and open flame. Keep container closed. Avoid contact with eyes and skin. Avoid breathing of vapor or spray mist. Use with adequate ventilation. Do not take internally.
A1.2 Compressed Gas Keep container closed. Use with adequate ventilation. Do not enter storage areas unless adequately ventilated. Always use a pressure regulator. Release regulator tension before opening cylinder. Do not transfer to cylinder other than one in which gas is received. Do not mix gases in cylinders. Do not drop cylinder. Make sure cylinder is supported at all times. Stand away from cylinder outlet when opening cylinder valve. Keep cylinder out of sun and away from heat. Keep cylinder from corrosive environment. Do not use cylinder without label. Do not use dented or damaged cylinder. For technical use only. Do not use for inhalation purposes.
Al.5 Hexamethyl Phosphoramide A potential carcinogen (lung). Avoid breathing vapor or mist. Avoid contact with skin, eyes, and clothing. Use with adequate ventilation. Keep container closed when not in use. Wash thoroughly after handling.
A1.6 Hydrogen Keep away from heat, sparks, and open flame. Use with adequate ventilation. Never drop cylinder. Make sure cylinder is supported at all times. Keep cylinder out of sun and away from heat. Always use a pressure regulator. Release regulator tension before opening cylinder. Do not transfer cylinder contents to another cylinder. Do not mix gases in cylinder. Keep cylinder valve closed when not in use. Do not inhale. Do not enter storage areas unless adequately ventilated. Stand away from cylinder outlet when opening cylinder valve. Keep cylinder from corrosive environment.
A1.3 Flammable Gas Keep away from heat, sparks and open flame. Use with adequate ventilation. Never drop cylinder. Make sure cylinder is supported at all times. Keep cylinder out of sun and away from heat. Always use a pressure regulator. Release regulator tension before opening cylinder. Do not transfer cylinder contents to another cylinder. Do not mix gases in cylinder. Keep cylinder valve closed when not in use. Do not inhale. Do not enter storage areas unless adequately ventilated. Stand away from cylinder outlet when opening cylinder valve. Keep cylinder from corrosive environment.
A1.7 n-Hexadecane Keep away from heat, sparks, and open flame. Keep container closed. Use with adequate ventilation. Avoid breathing vapor or spray mist. Avoid prolonged or repeated contact with skin.
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five yeers and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at e meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
378
(~l~
Designation: D 2549 - 91
Standard Test Method for Separation of Representative Aromatics and Nonaromatics Fractions of High-Boiling Oils by Elution Chromatography 1 This standard is issued under the fixed designation D 2549; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (0 indicates an editorial change since the last revision or reapproval.
3. Terminology 3.1 Descriptions of Terms Specific to This Standard." 3.1.1 aromatics fraction--the portion of the sample desorbed with the polar eluants. The aromatics fraction may contain aromatics, condensed naphthenic-aromatics, aromatic olefins, and compounds containing sulfur, nitrogen, and oxygen atoms, 3.1.2 nonaromatics fraction--the portion of the sample eluted with n-pentane. The nonaromatics fraction is a mixture of paraffinic and naphthenic hydrocarbons if the sample is a straight-run material. If the sample is a cracked stock, the nonaromatics fraction will also contain aliphatic and cyclic olefins.
1. Scope 1.1 This test method covers the separation and determination of representative aromatics and nonaromatics fractions from hydrocarbon mixtures that boil between 232 and 538"C (450 and 1000°F). Alternative procedures are provided for the separation of 2 g or 10 g of hydrocarbon mixture. NOTE l - - S o m e components may not be eluted from the chromatographic column for some types of samples under the conditions used in this method. NOTE 2 - - T e s t Method D 2007 is an alternative method of separating high-boiling oils into polar compounds, aromatics, and saturates fractions.
1.2 An alternative procedure is provided to handle samples boiling below 232°C (450"F), but whose 5 % point is above 178"C (350°F) as determined by Test Method D 2887. This procedure is given in Annex A 1. 1.3 The values stated in acceptable SI units are to be regarded as the standard. The values given in parentheses are provided for information purposes only. 1.4 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
4. Summary of Test Method 4.1 A weighed amount of sample is charged to the top of a glass chromatographic column packed with activated bauxite and silica gel. n-Pentane is added to the column to elute the nonaromatics. When all of the nonaromatics are eluted, the aromatics fraction is eluted by additions of diethyl ether, chloroform, and ethyl alcohol. 4.2 The solvents are completely removed by evaporation, and the residues are weighed and calculated as the aromatics and nonaromatics fractions of the sample. 5. Significance and Use 5.1 The determination of compound types by mass spectrometry requires, in some instances, a preliminary separation of the petroleum sample into representative aromatics and nonaromatics fractions, as in Test Methods D 2425, D 2786, and D 3239. This test method provides a suitable separation technique for this application.
2. Referenced Documents
2.1 A S T M Standards: D 2007 Test Method for Characteristic Groups in Rubber Extender and Processing Oils and Other PetroleumDerived Oils by the Clay-Gel Adsorption Chromatographic Method2 D2425 Test Method for Hydrocarbon Types in Middle Distillates by Mass Spectrometry2 D 2786 Test Method for Hydrocarbon Types Analysis of Gas-Oil Saturate Fractions by High Ionizing Voltage Mass Spectrometry2 D2887 Test Method for Boiling Range Distribution of Petroleum Fractions by Gas Chromatography2 D3239 Test Method for Aromatic Types Analysis of Gas-Oil Aromatic Fractions by High Ionizing Voltage Mass Spectrometry2
6. Apparatus 6.1 Chromatographic Columns,, as shown in Fig. 1. Different chromatographic columns are provided for the analysis of 2 and 10-g samples. 6.2 Beakers, 100, 250, and 600-mL, inverted-rim type) 6.3 Steam Bath. 6.4 Electric Vibrator, for packing column. 6.5 Weighing Bottles or Erlenmeyer Flasks, 25 and 50 mL.
This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.04 on Hydrocarbon Analysis. Current edition approved March 15, 1991. Published June 1991. Originally published as D 2549 - 66 T. Last previous edition D 2549 - 85 ~, 2 Annual Book of ASTM Standards, Vol 05.02.
7. Reagents and Materials 3 Beakers available from Kontes Glass Co., Vineland, NJ, by ordering "AfitiCreep" beakers and referring to Drawing No. 9413-A.
379
(~ D 2549
200 ML BULB
_,/ 100 ML BULB
28/15 SPHERICAL J O I N T ~ " ~ ~ "
•
O
:E
GLAZED MARKERS
=o
:E =E O 1,O
:E 3E O tD
0 O0 p~
MM OPENING 10 MM ID FOR 2-GRAM SAMPLES 3 MM OPENING 15 MM ID FOR 10-GRAM SAMPLES FIG. 1 Chromatographic Columns
oxidizer, contact with organic material may cause fire. See Annex A2.2.). 7.5 Diethyl Ether, anhydrous, (Warning--Extremely flammable.). The ethyl ether used in this test method should be free of peroxides as determined by the procedure in "Reagent Chemical, American Chemical Society Specifications." 7.6 Ethyl Alcohol, denatured, conforming to Formula 2B of the U.S. Bureau of Internal Revenue (WarningnFlammable.). 7.7 Pressuring Gas, dry air or nitrogen, delivered to the top of the column at a regulated gage pressure of 0 to 2 psi (13.8 kPa) (WarningnCompressed gas.). 7.8 n-Pentane, commercial grade, aromatic-free. Some samples of waxy stocks may not dissolve completely in n-pentane, in which case cyclohexane, commercial grade, aromatic-free, may be substituted for n-pentane (Warning-Extremely flammable liquid.). 7.9 Silica Gel,6 100 to 200-mesh.
7.1 Purity of Reagents--Reagent grade chemicals shall be used in this test. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available. 4 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 7.2 Bauxite, 5 20 to 60-mesh. Before use, activate the bauxite by heating at 538"C (1000*F) for 16 h. Transfer the activated material to an airtight container while still hot and protect thereafter from atmospheric moisture. 7.3 Chloroform (Warning--Toxic. May be fatal if swallowed. See Annex A2.1.). 7.4 Cleaning Solution--Chromic- sulfuric acid (Warning--Causes severe burns. A recognized carcinogen, strong 4 "Reagent Chemicals, American Chemical Society Specifications," Am. Chemical Soc., Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see "Reagent Chemicals and Standards," by Joseph Rosin, D. Van Nostrand Co., Inc., New York, NY, and the "United States Pharmacopeia." .s Bauxite available from Porocel Corp., Little Rock, AR.
6 Silica gel available from W.R. Grace and Co., Davison Chemical Div., Baltimore, MD 21203, by specifying Code 923.
380
~
D 2549
8. Procedure NOTE 3--The procedural details differ depending on the initial boiling point of the sample. If the 5 % point is above 178"C(350"F), but below 232"C (450"F) use procedure described in Annex A1. If above 232"C continue as written depending on amount of sample to be analyzed. Instructions specific for 2-g samples are given in 8.4.1 to 8.4.13, and instructions specific for 10-g samples are given in 8.5.1 and 8.5.8. 8.1 Select the appropriate column, depending on whether 2 or l0 g of sample are to be analyzed. Clean the column with chromic-sulfuric acid, (Warning--Causes severe burns. See Annex A2.2.) followed by distilled or demineralized water, acetone, and dry air or nitrogen. 8.2 Introduce a small plug of glass wool into the column, pressing it firmly into the lower end to prevent the flow of silica gel from the column. 8.3 Clamp the column in a vertical position. Add small increments of silica gel, while vibrating the column along its length, until the tightly packed silica gel extends to the lower mark on the chromatographic column. Continue to vibrate the column and add bauxite until the bauxite layer extends to the upper mark on the chromatographic column. Vibrate the column for an additional 3 min after filling is completed. 8.4 If 2 g of sample are to be analyzed, continue as in 8.4.1, otherwise continue as in 8.5. 8.4.1 If the sample is viscous, warm it with intermittent mixing or shaking until it is completely fluid. Transfer a representative sample (approximately 2 g) to a 25-mL weighing bottle or flask. Determine the weight of the sample to the nearest 1 mg by weighing the flask before and after sample transfer. Add 10 m L of n-pentane (Warning-Extremely flammable liquid.) to the flask and dissolve the sample. If the sample does not dissolve completely in cold n-pentane, warm it in warm water or over a steam bath. If the sample does not dissolve in warm n-pentane, take a fresh sample and substitute cyclohexane for the n-pentane. 8.4.2 Add l0 m L ofn-pentane to the top of the column to prewet the adsorbent. When the liquid level reaches the top of the bauxite bed, transfer the sample solution from the weighing flask to the top of the column. Rinse the flask with three successive 3-mL washes of n-pentane. Add each wash to the top of the column. Then rinse the walls of the column bulb with two 3-mL portions of n-pentane, allowing the liquid level to reach the top of the bauxite bed before adding the next portion. Finally add 35 m L of n-pentane to the column bulb. 8.4.3 Place a 50-mL graduate beneath the column to collect the eluate. The elution rate should be approximately 1 mL/min. NOTE 4--Gas pressure (Warning--Compressed gas.) can be applied to the top of the column as necessary to maintain the elution rate at approximately 1 mL/min. If the correct pressure setting is known from previous runs, gas pressure may be applied alter addition of the last increment of n-pentane. Otherwise, gas pressure should be applied when n-pentane begins to elute from the column and should be adjusted to give a flow rate of approximately 1 mL/min. 8.4.4 When the n-pentane level reaches the top of the bauxite bed, add 80 m L of diethyl ether (Warning-Extremely flammable.). Connect the pressuring gas to the top of the column and adjust the pressure to maintain an elution rate of l to 2 mL/min. 381
8.4.5 Collect 50 m L of n-pentane eluate in the graduate. Rinse the tip of the column with 1 to 2 m L of n-pentane, adding this to the 50 m L in the graduate (Note 5). Label the 50-mL graduate as n-pentane eluate. NOTE 5--The n-pentane will have reached the adsorbent bed before the required volume of eluate has been collected in the 50-mL receiver. Continue collection in this receiver after the addition of ether until the proper volume has been collected before changing to the 100-mL graduate. 8.4.6 When the ether level reaches the top of the bauxite bed, release the gas pressure and add 100 m L of chloroform (Warning--Toxic. May be fatal if swallowed.) to the top of the column. Reconnect the gas pressuring system and continue the elution. When 80 m L of eluate have been collected in the graduate, rinse the column tip with 1 m L of ether and add the rinse to the 100-mL graduate. Change the receiver to a 250-mL graduate. Label the 100-mL graduate as ether-eluted fraction. 8.4.7 When the chloroform level reaches the top of the bauxite bed, release the gas pressure and add 75 m L of ethyl alcohol (Warning--Flammable liquid.). Reconnect the gas pressuring system and continue the elution until the alcohol level reaches the top of the bauxite bed. Release the gas pressure. Rinse the column tip with 1 m L of chloroform adding this to the graduate. Label the 250-mL graduate as chloroform-alcohol-eluted fraction. 8.4.8 Weigh a 100-mL inverted-tim beaker to the nearest 1 mg. Quantitatively transfer the n-pentane eluate to this beaker and allow the n-pentane to evaporate at room temperature. Cyclohexane, if used as the elution solvent, is evaporated on a steam bath. Evaporation is accelerated in both cases by directing a controlled stream of dry nitrogen downward onto the surface of the liquid. 8.4.9 When all the solvent appears to be evaporated, stop the nitrogen flow, allow the beaker to come to room temperature, and dry the outside of the beaker to remove any condensed moisture. Reweigh the beaker to the nearest 1
mg. NOTI~ 6--Complete solvent evaporation is indicated by a tendency of the oil to creep up the side of the beaker. 8.4. l0 Repeat the evaporation step for 5-rain periods until the weight loss between successive evaporations is less than 20 mg. Heat from a steam bath is generally required during the final evaporation steps to remove completely the elution solvent. The weight of the residue in the beaker is the quantity of the nonaromatics fraction. 8.4.11 Weigh a 250-mL inverted-rim beaker to the nearest 1 mg. Quantitatively transfer the chloroform-alcohol-eluted fraction to this beaker and evaporate on a steam bath with a controlled stream of dry nitrogen directed downward onto the surface of the liquid. When the solvent is evaporated, remove the beaker from the steam bath, cool to room temperature, and add quantitatively the ether-eluted fraction. Evaporate the ether at room temperature as described in 8.4.8, 8.4.9, and 8.4.10. Determine the weight of the residue (aromatics fraction) to the nearest 1 rag. 8.4.12 The weight of the aromatics plus the nonaromatics fraction recovered must equal at least 95 % of the sample charged. If 95 % recovery is not obtained, repeat the test. Recoveries greater than 100 % indicates incomplete removal
~
D 2549
of solvent or the condensation of moisture in the beakers. 8.4.13 Transfer the aromatics and nonaromatics fractions into suitable size vials for storage pending further analysis. 8.5 If 10 g of sample are to be analyzed, continue as in 8.5.1. 8.5.1 Warm the sample with intermittent mixing or shaking until it is completely fluid. Transfer a representative sample (approximately 8 to I0 g) to a 50-mL weighing bottle or flask. Determine the weight of the sample to the nearest 1 mg by weighing the flask before and after sample transfer. Add 20 m L of n-pentane to the flask and dissolve the sample. If the sample does not dissolve completely in cold n-pentane warm it in warm water or over a steam bath. If the sample does not dissolve in warm n-pentane, take a fresh sample and substitute cyclohexane for n-pentane. 8.5.2 Add 45 m L ofn-pentane to the top of the prepacked large column to prewet the adsorbent. When the n-pentane level reaches the top of the bauxite bed, transfer the sample solution from the weighing flask to the top of the column. Rinse the flask with three successive 3-mL washes of n-pentane. Add each wash to the top of the column. Then rinse the walls of the column bulb with two 3-mL portions of n-pentane, allowing the level of each portion to reach the top of the bauxite bed before adding the next portion. Finally add 70 m L of n-pentane to the column bulb. 8.5.3 Place a 200-mL graduate beneath the column to collect the eluate. The elution rate should be approximately 3 mL/min. NOTE 7--Air or nitrogen pressure may be applied to the top of the column as necessary to accomplish and maintain a satisfactory elution rate. Three to five pounds of pressure generally is sufficient. If the correct pressure setting is known from previous runs, gas pressure can be applied after addition of the last increment of n-pentane. Otherwise, gas pressure should be applied when n-pentane begins to elute from the column and should be adjusted to give a flow rate of approximately 3 mL/min. 8.5.4 When the n-pentane level reaches the top of the bauxite bed, add 100 m L of diethyl ether. Connect the pressuring gas to the top of the column and adjust the pressure to maintain an elution rate of 3 to 5 mL/min. 8.5.5 Collect 130 m L of eluate in the graduate. Rinse the tip of the column with l to 2 m L of n-pentane, adding this to the 130 m L in the graduate. Change the receiver to a 100-mL graduate (Note 8). Label the 200-mL graduate as n-pentane eluate. NOTE 8--The n-pentane will have reached the absorbent bed before the required volume ofeluate has been collected in the 200-mL receiver. Continue collection in this receiver after the addition of ether until the proper volume has been collected before changing to the 100-mL graduate.
8.5.7 When the chloroform level reaches the top of the bauxite bed, release the gas pressure and add 175 mL of ethyl alcohol. Reconnect the gas pressuring systems and continue the elution until the alcohol level reaches the top of the bauxite bed. Release the gas pressure. Rinse the column tip with 1 m L of chloroform adding this to the graduate. Label the 500-mL graduate as chloroform-alcohol-eluted fraction. 8.5.8 Weigh a 250-mL inverted rim beaker to the nearest 1 mg. Quantitatively transfer the n-pentane eluate to this beaker and evaporate the solvent on a steam bath. Evaporation can be accelerated by directing a controlled stream of dry nitrogen downward onto the surface of the liquid. Complete the workup of the nonaromatics fraction as described in 8.4.9 and 8.4.10. 8.5.9 Weigh a 600-mL inverted rim beaker to the nearest l m g (Note 9). Complete the workup of the aromatics fraction as described in 8.4. l l, 8.4.12, and 8.4.13. NOTE 9--The 600-mL inverted-rim beakers from some sources can exceed the capacity of the standard analytical balance, in which case a 250-mL inverted rim beaker can be used, and the chloroform-alcoholeluted fraction evaporated in increments. 9. Calculation 9.1 Calculate the percentage of the aromatics fraction and the nonaromatics fraction as follows: Aromatics fraction, w~ % -- [A/(A + B)] x 100 (l) Nonaromatics fraction, wt % = [B/(A + B)] x I00 (2) where: A = weight of aromatics fraction recovered, and B = weight of nonaromatics fraction recovered. 10. Precision and Bias 10.1 The following criteria should be used for judging the acceptability of results (95 % probability): 10.1.1 R e p e a t a b i l i t y D T h e difference between successive test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, and in the normal arid correct operation of the test method, exceed the following values only in one case in twenty: 0.4 weight % for 10 g of sample; and 1.4 weight % for 2 g of sample. 10.1.2 Reproducibility--The difference between two, single and independent results, obtained by different operators working in different laboratories on identical test material would, in the long run, and in the normal and correct operation of the test method, exceed the following values only in one case in twenty: 1.6 weight % for l0 g of sample; and 1.5 weight % for 2 g of sample. NOTE 10--The procedure for analyzing 2 g of sample gives recoveries of aromatics fractions that are on average 0.35 weight % lower than the procedure for analyzing l0 g of sample.
8.5.6 When the ether level reaches the top of the bauxite bed, release the gas pressure and add 100 m L of chloroform to the top of the column. Reconnect the gas pressuring system and continue with the elution. When 100 m L of eluate have been collected in the graduate, rinse the column tip with 1 m L of ether and then change the receiver to a 500-mL graduate. Label the 100-mL graduate as ether-eluted fraction.
I0.2 B i a s D B i a s cannot be determined because there are no reference materials suitable for determining the bias in this test method. NOTE l l--The precision of the procedure in Annex A l has not been determined.
382
4t~ D 2549
ANNEXES
(Mandatory Information) AI. L O W E R BOILING S A M P L E PROCEDURE A1.5.12 Separate weighing bottle containing the concentrated pentane solution from the flask and weigh it after it has cooled to room temperature. A1.5.13 Gently swirl weighing bottle on the hot steam bath surface while directing a gentle stream of nitrogen to the bottle (Note AI.1). After 3 min, cool to room temperature and weigh. NOTE A I.I--Use nitrogen rate of approximately 100 mL/min. Do not direct nitrogen flow on liquid, but rather along inside of weighing bottle. A1.5.14 Repeat step A1.5.13 at 2-min intervals until weight loss between successive evaporations is less than 50 mg. The weight of the residue in the weighing bottle is the nonaromatic fraction. A1.5.15 Quantitatively transfer the chloroform-alcoholeluted fraction from A1.5.10 to a 600-mL beaker and evaporate off the solvent on a steam bath using a stream of nitrogen to facilitate the evaporation rate. Allow to cool to room temperature. A1.5.16 Weigh a 30-mL conical weighing bottle and attach to Kuderna-Danish apparatus as .described in A 1.5.11. Transfer the ether-eluted fraction A1.5.9 into the beaker containing the residue from A1.5.15. Quantitatively transfer this mixture into the flask and evaporate on the steam bath as described in A1.5.11. A1.5.17 Complete the workup of the aromatic fraction as described in A1.5.12, A1.5.13, and A1.5.14. AI.5.18 Same as 8.4.12. A1.5.19 Same as 8.4.13.
AI.1 Scope A1.1.1 This procedure covers the separation and determination of representative aromatics and nonaromatics fractions from hydrocarbon mixtures whose 5 % boiling point is below 232"C (450"F), but above 178"C (350"F). AI.2 Summary of Method A I.2.1 A Kuderna-Danish apparatus is used to evaporate solvents from the aromatic and nonaromatic fractions.
AI.3 Significance and Use A1.3.1 This procedure extends the range of this test method to separate the samples whose boiling range is specified in Test Methods D 2425, D 2786, and D 3239, all of which refer to this method to provide fractions for analyses. A1.4 Apparatus A 1.4.1 Kuderna-Danish Evaporator." A1.4.1.1 250-mL Flask, with top female standard taper 24/40 and bottom male standard taper 24/12 with glass hooks for retaining springs. A1.4.1.2 Macro Snyder Distillation Column, 3 ball, with male standard taper 24/40. AI.4.1.3 Conical Weighing Bottles, with female standard taper 24/12, 30-mL capacity with glass hooks for retaining springs. AI.5 Procedure A1.5.1 The 10-g chromatographic column is used. Clean column with chromic-sulfuric acid, distilled or demineralized water, acetone, and dry air or nitrogen. AI.5.2 Same as 8.2. AI.5.3 Same as 8.3. A1.5.4 Same as 8.5.1 AI.5.5 Same as 8.5.2. A1.5.6 Same as 8.5.3. A1.5.7 Same as 8.5.4. A1.5.8 Same as 8.5.5. A1.5.9 Same as 8.5.6. A1.5.10 Same as 8.5.7. A1.5.11 Weigh a 30-mL conical weighing bottle, to which a boiling chip is added, to the nearest 1 mg. Attach the weighing bottle to the 250-mL flask with the retaining springs. Quantitatively transfer the n-pentane eluate to the flask. Attach the Snyder distillation column to the flask and evaporate on a steam bath. Evaporation of most of the n-pentane is complete when balls in the Snyder distillation column stop moving.
AI.6 Calculation AI.6.1 Same as 9.1. A1.7 Results AI.7.1 Two samples representing aromatic and nonaromatic concentrates from a middle distillate with an initial boiling point 149"C (300*F) were subjected to the evaporation procedure. Interlaboratory testing on the preceding samples was done by five laboratories, in duplicate, at two different times. Recoveries of 97 to 102 % with less than 3 % solvent remaining were obtained in the last study. A1.8 Precision and Bias A1.8.1 There are no interlaboratory test data to establish a statistical statement of precision for the procedure in Annex A1 of Test Method D 2549. A1.8.2 There are no interlaboratory test data to establish a statistical statement of bias for the procedure in Annex A I of Test method D 2549.
383
(@) D 2549 The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you fee/that your comments have not received a fair heanng you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
384
~T~
Designation: D 2593 - 93
@
Designation: 194/74
An American National Standard
Standard Test Method for Butadiene Purity and Hydrocarbon Impurities by Gas Chromatography 1 This standard is issued under the fixed designation D 2593; the number immediately following the desisnation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval. This test method was adopted as a joint ASTM-IP Standard in 1972.
1. Scope 1.1 This test method provides for the determination of butadiene-l,3 purity and impurities such as propane, propylene, isobutane, n-butane, butene-l, isobutylene, propadiene, trans-butene-2, cis-butene-2, butadiene-l,2, pentadiene-l,4, and, methyl, dimethyl, ethyl, and vinyl acetylene in polymerization grade butadiene by gas chromatography. Impurities including butadiene dimer, carbonyls, inhibitor, and residue are measured by appropriate ASTM procedures and the results used to normalize the component distribution obtained by chromatography. NOTEl--Otherimpurities present in commercialbutadiene must be calibrated and analyzed. Other impurities were not tested in the cooperative work on this test method. Nor~ 2--This test method can be used to cheek for pentadiene-l,4 and other Css instead of Test Method D 1088. 1.2 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Notes 4, 5, and 9.
peak areas or peak heights and the relative concentration determined by relating individual peak response to total peak response. Impurities including butadiene dimer, carbonyls, inhibitor, and residue are measured by appropriate ASTM procedures and the results used to normalize the distribution obtained by gas chromatography.
4. Significanceand Use 4.1 The trace hydrocarbon compounds listed can have an effect in the commercial use of butadiene. This test method is suitable for use in process quality control and in setting specifications. 5. Apparatus 5.1 Chromatograph--Any chromatograph having either a thermal-conductivity or flame ionization detector can be used provided the system has sufficient sensitivity and stability to obtain a recorder deflection of at least 2 mm at signal-to-noise ratio of at least 5:1 for 0.01 weight % of impurity. 5.2 Column--Any column can be used that is capable of resolving the components listed in 1.1 with the exception of butene-1 and isobutylene, which can be eluted together. The components should be resolved into distinct peaks such that the ratio A / B will not be less than 0.5 where A is the depth of the valley on either side of peak B and B is the height above the baseline of the smaller of any two adjacent peaks. In the case where the small combonent peak is adjacent to a large one, it can be necessary to construct a baseline of the small peak tangent to the curve as shown in Fig. 1. 5.2.1 A description of columns that meet the requirements of this test method is tabulated in the Appendix. Persons using other column materials must establish that the column gives results that meet the precision requirements of Section 11. 5.3 Sample Inlet System--Means shall be provided for introducing a measured quantity of representative sample into the column. Pressure-sampling devices can be used to inject a small amount of liquid directly into the carrier gas. Introduction can also be accomplished by use of a gas valve to charge the vaporized liquid. 5.4 Recorder--A recording potentiometer with a full-scale deflection of 10 mV or less is suitable for obtaining the chromatographic data. Full-scale response time should be 2 s or less, and with sufficient sensitivity to meet the requirements of 5.1.
2. ReferencedDocuments 2.1 A S T M Standards: D 1088 Test Method for Boiling Point Range of Polymerization-Grade Butadiene 2 E 260 Practice for Packed Column Gas Chromatography 3
3. Summaryof Test Method 3. I A representative sample is introduced into a gas-liquid partition column. The butadiene and other components are separated as they are transported through the column by an inert cartier gas. Their presence in the effluent is measured by a detector and recorded as a chromatogram. The chromatogram of the sample is interpreted by applying component attenuation and detector response factors to the i This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.D on Hydrocarbons for Chemical and Special Uses. Current edition approved Feb. 15, 1993. Published April 1993. Originally published as D 2593 - 67. Last previous edition D 2593 - 86. 2 Discontinued; See 1984 Annual Book of ASTM Standards, Vol 05.01. 3 Annual Book of ASTM Standards, Vol 14.01.
385
i1~) D 2 5 9 3
NOTE 3--Other methods of recording detector output such as computer-teletype systemscan be used instead of a recorder, provided precision requirements of Section I l are met. 6. Reagents and Materials 6.1 CarrierGas--A carrier gas appropriate to the type of detector used should be employed. Helium or hydrogen may be used with thermal conductivity detectors. Nitrogen, helium, or argon may be used with ionization detectors. The minimum purity of any carder should be 99.95 tool %. NOTE 4: Warning--Compressedgas. Hazardous pressure. NOT~ 5: Warning:--Hydrogen flammablegas. Hazardous pressure. 6.1.1 If hydrogen is used, special safety precautions must be taken to ensure that the system is free from leaks and that the effluent is properly vented. 6.2 Column Materials: 6.2.1 Liquid Phase--The materials that have been used successfully in cooperative work as liquid phases are listed in the Appendix (Table X 1.1). 6.2.2 Solid Support--The support for use in the packed column is usually crushed firebrick or diatomaceous earth. Sieve size will depend on the diameter of the column used and liquid-phase loading, and should be such as would give optimum resolution and analysis time. Optimum size ranges cannot be predicted on purely theoretical grounds. For some systems it has been found that a ratio of average particle diameter to column inside diameter of 1:25 will result in minimum retention time and minimum band widths. 6.2.3 Tubing Material--Copper, stainless steel, Monel, aluminum, and various plastic materials have been found to be satisfactory for column tubing. The material must be nonreactive with respect to substrate, sample, and carder gas and of uniform internal diameter. 6.3 Hydrocarbons for Calibration and Identification-Hydrocarbon standards for all components present are needed for identification by retention time and for calibration for quantitative measurements. NOTE 6--Mixtures of hydrocarbons can be used provided there is no uncertainty as to the identity or concentration of the compounds involved. 7. Preparation of Apparatus
7.1 Column Preparation--The technique used to prepare
the column is not critical as long as the finished column produces the desired separation. Preparation of the packing is not difficult once the support, partitioning liquid, and loading level have been determined. The following general directions have been found to produce columns of acceptable characteristics. 7.1.1 Weigh out the desired quantity of support, usually twice that required to fill the column. 7.1.2 Calculate and weigh out the required quantity of partitioning agent. Dissolve the partitioning agent in a volume of chemically inert, low-boiling solvent equal to approximately twice the volume of support. 7.1.3 Gradually add the support material to the solution with gentle stirring. 7.1.4 Slowly evaporate the solvent while gently agitating the mixture until the packing is nearly dry and no free liquid is apparent. 7.1.4.1 Some stationary phases such as benzyl cyanide silver nitrate are susceptible to oxidation and must be protected from excessive exposure to air during the evaporation and drying steps. 7.1.5 Spread the packing in thin layers on a nonabsorbent surface and air- or oven-dry as required to remove all traces of solvent. 7.1.6 Resieve the packing to remove fines and agglomerates produced in the impregnation step. 7.1.7 Fill the column tubing with packing by plugging one end with glass wool and pouring the packing into the other end through a small funnel. Vibrate the tubing continuously over its entire length while filling. When the packing ceases to flow, tap the column gently on the floor or bench-top while vibrating is continued. Add packing as necessary until no further settling occurs during a 2-rain period. Remove a small amount of packing from the open end, plug with glass wool, and shape the column to fit the chromatograph. 7.2 Chromatograph--Mount the column in the chromatograph and establish the operating conditions required to give the desired separation (Appendix X l). Allow sufficient time for the instrument to reach equilibrium as indicated by a stable base line. Control the oven temperature so that it is constant to within 0.5"C without thermostat cycling which causes an uneven base line. Set the carder-gas flow rate, measured with a soap film meter, so that it is constant to within 1 mL/min of the selected value. 8. Calibration
8.1 Identification--Select the conditions of column temperature and carrier gas flow that will give the necessary separation. Determine the retention time for each compound by injecting small amounts of the compound either separately or in mixtures. Recommended sample sizes for retention data are 1 ~tL for liquids and 1 cm 3 or less for gases. 8.2 Standardization--The area under the peak of the chromatogram is considered a quantitative measure of the amount of the corresponding compound. The relative area is proportional to the concentration if the detector responses of the sample components are equal. The recommended procedure for quantitative calibration is as follows: with all equipment at equilibrium at operating conditions, inject
FIG. 1 Illustration of A/B Ratio for Small-Component Peak
386
i ~ D 2593 constant volume samples of high-purity components. Each compound should be injected at least three times. The areas of the corresponding peaks should agree within 1%. When a recorder is used, adjust the attenuation in all cases to keep the peak on-scale and with a height of at least 50 % of full scale. Measure the area of the peaks by any reliable method (Note 10). To obtain component weight % response data from the area response of the volume injections, it is necessary to consider the density and purity of the compounds used for calibration. The average volume area response of each component is divided by the density multiplied by the weight percent purity of the component as follows: Weight percent response of component (1) average component peak area density × weight percent purity of component Component weight percent detector correction factors are then obtained by selecting a reference component such as butadiene, and dividing the individual component weight responses into the reference weight response. 8.2.1 Factors derived on a thermal-conductivity detector using helium-carrier gas are as follows: Component Butadiene- 1,3 Propane Propylene Isobutane n.Butane Butene- I Isobutylene
trans.Butene-2 cis-Butene-2 Propadiene Methyl acetylene
Mol wt
Thermal Response
Weight Factor
Weight Factor, Butadiene- 1,3 = 1.00
54 44 42 58 58 56 56 56 56 40 40
80 65 63 82 85 81 82 85 87 53 58
0.68 0.68 0.67 0.71 0.68 0.69 0.68 0.66 0.64 0.75 0.69
1.00 1.00 0.98 1.04 1.00 1.01 1.00 0.97 0.94 1.10 1.01
NOTE 7--Response based on data represented by Messner, A. E., Rosie, D. M., and Argabright, P. A., Analytical Chemistry, Vol 31, 1959, pp. 230-233, and Dietz, W. A., Journal of Gas Chromatography, Vol 5, No. 2, 1967, pp. 68-71.
function of the carbon content, giving essentially equal relative response to hydrocarbons containing the same number of carbon atoms.
8.2.3 Because detector or amplifier output need not be linear with component concentration, this must be checked by injecting constant volumes of pure butadiene at a series of decreasing pressures from ambient down to 20 mm Hg (ton') or by using synthetic standards with vapor sample valves at ambient or at decreasing pressures or by using synthetic standards with liquid sample valves. If on plotting the results the response is linear, then the calibration procedure given above is satisfactory. If not, the relative responses of the minor components must be determined in the linear response region. 9. Procedure
9.1 Attach the sample cylinder to the instrument-sampiing valve so that the sample is obtained from the liquid phase. If introduction is through a liquid valve the sample cylinders should be pressured with a suitable gas, such as helium, to a pressure sufficient to ensure that sample flashing does not occur in the line to the sampling valve or in the valve itself.If a vapor valve is used, care must be taken to completely vaporize a small liquid sample, allowing the vapor to flow through the sample loop at a flow rate of 5 to I0 mL/min until at leastten times the volume of the sample loop has been flushed through. If a vacuum-sampling system is used with a vapor valve, the sample loop should be filled and evacuated at least twice before introduction of sample. 9.2 Charge sufficient sample to ensure a m i n i m u m of 10 % recorder deflection for 0.1% concentration of impurity at the most sensitiveoperating settingof the instrument (for trace impurities, such as acetylenes, greater sensitivity is needed). 9.3 Using the same conditions as were used for calibration, record the peaks of all compounds at attenuation or sensitivitysettingsthat allow m a x i m u m peak heights. NOTE 9: Warning--Butadiene flammable gas under pressure.
10. Calculation
8.2.1.1 Although not determined with standards, weight factors of 1.00 (compared to butadiene 1,3 as 1.00) were used for pcntadiene-l,4 butadiene-l,2, dimethyl acetylene, ethyl and vinyl acetylene in this study to obtain the precision listed in Section 11. It is permissible to use the above established response factors instead of calibration when using thermalconductivity detectors with helium-carrier gas. With other detectors or carrier gas, or both, it is necessary to calibrate (Note 7). 8.2.2 Measurements can be made using peak heights as criteria for calculations instead of peak areas. If peak heights are used, care must be taken so that chromatographoperating parameters such as column temperature and carrier-gas flow rate are kept at the same conditions as when the unit was calibrated. The chromatograph can be calibrated using known blends or by establishing relativeresponse data using peak heights in the same manner as listed above.
10.1 Measure the area or heights of all peaks (Note 10) and multiply by the appropriate attenuation factor to express the peak area or heights on a common sensitivity basis. Apply the appropriate calibration factors to the peak areas or heights to correct for the differences in response to the components. Make area calculations by relating the individual component corrected area to the total corrected area of all peaks. If peak heights arc used, multiply the peak heights, calibration factors,and component attenuations for each component and normalize the resultingproducts to give percentages. Make corrections to account for the direct, carbonyl, inhibitor residue (and acetylene if not determined chromatographically) concentration as determined by separate A S T M procedures. Calculations arc as follows: Corrected peak response Sum of correctedpeak responses (2) I00 - sum of dimer, carbonyl,inhibitorand residual] x impurities(and acetyleneifnot determined chromatographically) NOTE 10raThe areacan be determinedby any method thatmeets the precision requirements of Section II. Methods found to be
J
NOTE S--Use of a hydrogen-flamedetector gives essentially equal relative responseto hydrocarbons. On a weight basis, the sensitivityof the flame detector for hydrocarbons is essentially independent of the hydrocarbons structure. On a molar basis, the sensitivityappears to be a 387
t{~ D 2593 11.1.2 Reproducibility---The difference between two single and independent results obtained by different operators working in different laboratories on identical test material would, in the long run, and in the normal and correct operation of the test method, exceed the following values only in one case in twenty:
acceptable include planimetering, integration (electronic or mechanical or computer processing), and triangulation (multiplying the peak height by the width at the half height).
11. Precision and Bias 4 11.1 The precision of the test method as determined by statistical examination of interlaboratory results is as follows: 11.1.1 Repeatability---The difference between successive test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, and in the normal and correct operation of the test method, exceed the following values only in one case in twenty: Component Butadiene-1,3 Propane Propadiene Propylene
lsobutane n-Butane Butene- I and isobutylene trans-Butene.2 cis-Butene.2
Butadiene- 1,2 Pentadiene- 1,4 Dimethyl acetylene Total methyl, ethyl + vinyl acetylene
Concentration, weight percent
Repeatability, weight percent
99.0 0,02 0. I I O.I 1 0.07 0.06 0.23 0.09 O. ! 3
0.079 0.005 0.013 0.017 0.010 0.008 0.01 I 0.008 0.016
0.08
0.016
0. i 2 0.05 0.034
0.0 ! 3 0.0l I 0.004
Concentration, Reproducibility,
Component Butadiene-i,3 Propane Propadiene Propylene lsobutane n-Butane Butene-I and isobutylene trans-Butene-2 cis-Butene-2
Butadiene- 1,2 Pentadiene- 1,4 Dimethyl acetylene Total methyl, ethyl + vinyl acetylene
weight percent
weight percent
99.0 0.02 0. I i 0. I I 0.07 0.06 0.23 0.09 0.13 0.08 0. ! 2 0.05 0.034
0.28 0.013 0.087 0.092 0.027 0.025 0.240 0.036 0.046 0.052 0.070 0.054 0.014
I 1.2 Bias--Since there is no acceptable reference material suitable for determining the bias for the procedure in this test method, bias has not been determined. 12. Keywords 12.1 butadiene; gas chromatography
4 Round-robin data for this method may be obtained from ASTM Headquartots. Request RR: D02-1004.
APPENDIX (Nonmandatory Information) Xl. COLUMNS AND CONDITIONS X I.I The columns and conditions given in Table X l.1 have been used successfully for this analysis in cooperative work. Columns and conditions other than those listed may
be used provided they are capable of meeting the resolution and precision requirements of the method.
TABLE XI.1 Appears on Followipg Pages
388
q~ D 2593
TABLE X1.1 Case I Column: Substrate Weight, Support Mesh size Treatment Length, m (ft) Diameter, mm (in.) Temperature, °C Carrier gas Flow rate, cm3/mtn Detector, type Voltage or mA Recorder, range, mV Speed, mm (in.)/min Sample Valve Size Split ratio Peak measurement Area or height Method Retention time, min Propane Propylene Isobutane n-Butane Butene*l Isobutylene Propadlene trans.Butene-2
bis-2-methoxy-ethoxy ethyl ether diisodecyl phthalateA 25 Chromosorb pe 60 to 80 no treatment 6.1 (20) 4.8 (S/la) 26 helium 60 thermal conductivity 7.5V 0to5 25.4 (1)
Chromatographic Conditions Case II
0to1
0to1 12.7 (l/z)
vapor 1 cms @ 15 in. vaccuum none
vapor 1 cma none
liquid 1.54 HL none
liquid 0.47 HL none
area triangulation
height
area triangulation
area planimeter
3.6 4.3 5.7 6.8 8.8 8.8 7.9 11.9 13.7 15.6 25.0 14.8 32.4 49.1 53.7 30.7
4.7 5.1 5.1 5.7 8.5 8.5 7.2 7.2 7.7 9.3 12.1
cia-Butene-2
11.7
Butadlene-1,3 Butadlene-1,2 Methyl acetylene Ethyl acetylene Vinyl acetylene Dimethyl acetylene Pentadiene-1,4
13.4 21.3 12.7 27.7 42.0 45.7 26.0
15 Chromosorb P 30 to 60 no treatment 6.1 (20) 4.8 pAe) 27 helium 60 thermal conductivity
3.4 3.7 4.6 5.5 6.2 6.2 5.1 7.2 7.8 11.5 6.2 12.3 14.8 22.0 18.4
389
bis-2-methoxy-ethoxy ethyl ether A dlisodecyl phthalate 25 Chromosorb P 60 to 80 no treatment 6.1 (20) 4.8 pAe) 26 helium 60 hydrogen flame
Case IV (1) sulfolanec (2) didecyl phthalate 30 Chromosorb P 60 to 80 no treatment (1) 6.4 (21) (2) 1.07 (3.5) 3.2 (Ve) 25 helium 12.5 thermal conductivity 8V 0to1 25,4 (1)
3.3 4.0 5.0 6.8 8.4 8.4 7.8 10.2
di-n-butyl maleate
Case 111
17.3 24.6 29.2 13.6
~
D 2593
TABLE X1.1
Continued CaseV
Column: Substrata Weight percent Support Mesh size Treatment Langth, m (ft) Diameter, mm (in.) Temperature, "C Carder gea Flow rate, crn~/min Detector, type Voltege or mA Recorder, range, mV Speed, mm (In.)/mln San~e Valve Size Split ratio Peak measurement Area or height Method Retention time, min Propane P ~ laobutane n-Butane Butane-1 laobuty~ne Propedlane trans-Butene-2 cle-Butane-2 Butadlane-1,3 Butadlane-1,2 Methyl acetylene Ethyl acetylene Vin~ acetykm Dlmethyl acetylene Pantadlane-1,4
(1) bis-2-rnethoxyemyl adipete o (2) 1,3-trla(2.cyanoethoxy)-propene 15 Chromosorb pm 60 to80 no treatment (I) 7.3 (24) (2) 1.8 (6) 6.4 (~) 65 helium 140 thermal conductivity 2O0 mA 0to1 12.7 (1/=)
I.ICON LB-550X =
B,B'-oxydiproplonitrila
20 Chromosorb P 60 to 80 no treatment 7.8 (29) 8.4 (~) 68 helium 110 thern~ condu~v|ty 2OO mA 0to1 12.7 (1/=)
20 Chromosorb P 60 to 80 no treatment 7.8 (25) 8.4 (~A) 25 helium 115 flame 3O0 mA 0to1 12.7 (½)
liquid 5 pL none
liquid 5 pL none
,qu~ 5 pL none
area disk integrator
area disk integrator
8re8 triangulation
5.3 6.1 7.5 7.7 9.3 9.5 9.5 10.5 11.5 13.0 17.6 11.8 21.3 27.7 33.1 19.8
5.2 5.5 6.6 8.0 8.4 8.4 7.4 9.3 9.6 9.6 13.8 8.0 13.4 18.5 21.2 15.8
4.5 5.2 4.9 5.2 6.7 6.9 8.2 7.4 8.2 10.9 13.5 14.1 20.8 28.3 35.8 14.1
390
(IN D 2593
T A B L E X1.1
Continued
Case Vl Column: Substrate Weight percent Support Mesh size Treatment Length, m (ft) Diameter, mm (in.) Temperature, °C Carder gas Flow rate, orn3/min Detector, type Voltage or mA Recorder, range, mV Speed, mm (in.)/min Sample Valve Size Split ratio Peak measurement Area or height Method Retention time, min Propane Propylene Isobutane n-Butane Butane-1 Isobutylane Propadiene trans-Butene-2 tie-Butane-2 Butadiane-1,3 Butadiane-1,2 Methyl acetylene Ethyl acetylene Vinyl acetylene Dimethyl acetylene Pentadlene-1,4
Case Vll
tributyl phosphate
B,B'-oxydiproplonitrile
15 Chromosorb pa 30 to 60 no treatment 18.3 (60) 3.2 (Y=) 25 helium 60 flame
13.7 (45) 4.8 p/le)
15 Chromosorb P 40 to 60
(I) squalane F (2) dimethyl sulfolane (1) 15 (2) 20 C-22 firebrick 60 to 80
(1) 20 (2) 20 C-22 firebrick 60 to 80
no treatment
no treatment
no treatment
6.1 (20) 3.2 (1A) 25 helium 45 flame
(1) 1.5 (5) (2) 4.6 (15) 4.8 p/l= ) 25 helium 36 thermal conductivity 300 mA 0to1 12.7 (Y=)
Case Vlll propylane carbonate 30 firebrick BS 60 to 85 (251 to 178 p.m) acid and water-washed and dded 4.9 (16) 4.8 (=/le) 30 ± 0.5 helium or hydrogen 55 to 65 thermal conductivity
0to1 25.4 (1)
0to1 25.4 (1)
(1) 1.7 (5%) (2) 7.0 (23) 6.4 (¼) 25 helium 84 thermal conductivity 310 mA 0to1 25.4 (1)
vapor 1.5 ore3 none
vapor 3 cm a none
liquid 3 I~L none
vapor vapor 8 cma @ 2 in. vacuum up to 2 mL none none
area triangulation
area triangulation
area triangulation
area triangulation
thermal conductivity 125 mA
8.9 9.7 13.9 18.6 20.5 20.5 16.0 24.8 14.8 30.0 43.5 22.3
2.24 2.64 2.64 3.04 3.92 4.16
7.2 7.9 9.1 12.6
4.48 4.96 6.24 8.40
28.4 14.8
56.6
peak height x retention time
3.8 4.2 4.6 5.7 6.2 6.2
9.0 17.0 24.0
7.0 9.5 12.8
()'to 10 12.5 p'/e,)
13.44 17.92 18.96 10.08
A Mixed bed column containing 18.5 parts of 25 weight % diisodecyl phthalate and 81.5 parts 25 weight ~ bis-2-methoxy-ethoxy ethyl ether. a *Chromosorb" is a trademark of Johns.Manville Products Corp. c Columns in sedas--8.4 m (21 ft) of sulfolane followed by 1.1 m (3.5 ft) of didecyl phthelate. o Columns in series--7.3 m (24 ft) of adipata followed by 1.8 m (6 ft) of tris-cyanoethoxy propane. *UCON" is a trademark of Union Carbide Corp. F Columns in sedas--1.7 m (5% ft) of squalane followed by 7.0 m (23 ft) of dimethyl sulfolane. o This column and chromatographic technique is described more fully in the Institute of Petroleum's Test Method IP 194, "Analysis of Butadiene-1,3 Polymedzation Grade."
The American Society for Tasting end Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard ere expressly advised that determination of the validity of any such patent rights, and the risk of infr/ngemant of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and ff not revised, either raspproved or withdrawn. Your comments ere invited either for revision of thia atandard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
391
Designation:D 2597 - 94
An AmericanNationalStandard
Standard Test Method for Analysis of Demethanized Hydrocarbon Liquid Mixtures Containing Nitrogen and Carbon Dioxide by Gas Chromatography I This standard is issued under the fixed designation D 2597; the number immediately following the designation indicates the year of original adoption or, in the ease of revision, the year of last revision. A number in parentheses indicates the year of last re.approval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 This test method covers the analysis of demethanized liquid hydrocarbon streams containing nitrogen/air and carbon dioxide, and purity products such as an ethane/ propane mix that fall within the compositional ranges listed in Table 1. This test method is limited to mixtures containing less than 5 tool % of heptanes and heavier fractions. 1.2 The heptanes and heavier fraction, when present in the sample, is analyzed by either (1) reverse flow of carrier gas after n-hexane and peak grouping or (2) precut column to elute heptanes and heavier first as a single peak. For purity mixes without heptanes and heavier no reverse of carrier flow is required. NOTE 1: Caution--Inthe case of unknownsampleswith a relatively large C6 plus or C7 plus fractionand wherepreciseresultsare important, it is desirable to determine the molecular weight (or other pertinent physical properties) of these fractions.Since this test method makes no provision for determining physical properties, the physical properties needed can be determinedby an extendedanalysisor agreed to by the contracting parties. 1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements see Annex A3. 2. Referenced Documents
2. I A S T M Standard." D 3700 Practice for Containing Hydrocarbon Fluid Sampies Using a Floating Piston Cylinder2 2.2 Other Standard." GPA Standard 2177 Analysis of Demethanized Hydrocarbon Liquid Mixtures Containing Nitrogen and Carbon Dioxide by Gas Chromatography3 3. Summary of Test Method 3.1 Components to be determined in a demethanized i This test method is under the jurisdiction of Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.H on Liquefied Petroleum Gas. Current edition approved July 15, 1994. Published September 1994. Originally published as D 2597 - 67T. Last previous edition D 2597 - 88. 2 Annual Book of ASTM Standards, Vol 05.02. 3 Available from Gas Processors Assn., 6526 E. 60th St., Tulsa, OK 74145.
392
TABLE 1
Componentsand Compositional Ranges Allowed Components
Nitrogen Carbon Dioxide Methane
Ethane Propane Isobutane n-Butane and 2,2-Dimethylpropane Isopentane n-Pantane 2,2-Dlmothylbutane 2,3-Dlmethylbutane and 2.Methylpentane 3-Methylpentane and Cyclopentane n-Hexane Heptanes and Heavier
ConcentrationRange. M(~ 0.01-5.0 0.01-5.0 0.01-5.0 0.01-95.0 0.01-100.0 0.01-100.0 0.01-100.0 0.01-15.0 0.01-15.0 0.01-0.5 0.01-15.0 0.01-5.0
hydrocarbon liquid mixture are physically separated by gas chromatography and compared to calibration data obtained under identical operating conditions. A fLxed volume of sample in the liquid phase is isolated in a suitable sample inlet system and entered onto the chromatographic column. 3.1.1 Components nitrogen/air through n-hexane are individually separated with the carrier flow in the forward direction. The numerous heavy end components are grouped into an irregular shape peak by reversing direction of carder gas through the column by means of a switching valve immediately following the elution of normal hexane. (See Fig. 1.) Samples that contain no heptanes plus fraction are analyzed until the final component has eluted with no reverse of carder flow. 3.1.2 An alternative to the single column bacldlush method is the use of a precut column which is bacldlushed to obtain the heptanes plus as a single peak at the beginning of the chromatogram. Two advantages of the alternate method are as follows: (1) better precision in measuring the C7 plus portion of the sample and (2) reduction in analysis time over the single column approach by approximately 40 %. 3.2 The chromatogram is interpreted by comparing the areas of component peaks obtained from the unknown sample with corresponding areas obtained from a run of a selected reference standard. Any component in the unknown suspected to be outside the linearity range of the detector, with reference to the known amount of that component in the reference standard, must be determined by a response curve. Peak height method of integration can be used only if the chromatograph is operating in the linear range for all components analyzed. Linearity must be proved by peak height for all components when using peak height method.
~1~) D 2597 z i u~
~, tu LU
Column.--SiIcone 200/500, 30 ft. 1/8 in Oven Temperature--- 100"C Inlet Pressure--45 pslg Sample Size.-- 1 mlcmllter Deleclor Temperature--- 125"C Chart Speed.-- Frontal ROw lcm/min Reverse Flow 0.5 cm/mtn FIo Rate--- 23 ml/mi°
00,~la
FIG. 1 Chromatogrsm of Demethanized Hydrocarbon Liquid Mixture (Frontal Carder Gas Flow Through N-Hexane, Reverse Grouping Heptsnes Plus)
(See Section 6 for further explanation of instrument linearity check procedures.)
4. Significance and Use 4.1 The component distribution of hydrocarbon liquid mixtures is often required as a specification analysis for these materials. Wide use of these hydrocarbon mixtures as chemical feedstocks or as fuel require precise compositional data to ensure uniform quality of the reaction product. In addition, custody transfer of these products is often made on the basis of component analyses of liquid mixtures. 4.2 The component distribution data of hydrocarbon mixtures can be used to calculate physical properties such as specific gravity, vapor pressure, molecular weight, and other important properties. Precision and accuracy of compositional data are extremely important when these data are used to calculate physical properties of these products.
w
I
Column 1-- Silicone DC 200/500, 30 ft, 1/8in Column 2 - - Silicone DC 200/500, 1.5 fl, 1/8 in Oven Temperature.-- 125"C Inlet Pressure--- 95 psig Sample Size--- 0.5 microliter Detector Temperature-- 125"C
tu uJ ~_
~-
I
z ~
!11 1 z
.j
0
z~
w
~"
m
0
~z z
~
o
z
FIG. 2 Chromstogram of Demethanized Hydrocarbon Liquid Mixture (Precut Column Grouping Heptanes Plus, Frontal Carder Gas Flow Remaining Components)
5. Apparatus 5.1 Any gas chromatograph can be used that meets the following specifications. 5.1. I Detector--The detector shall be a thermal-conductivity type. It must be sufficiently sensitive to produce a deflection of at least 0.5 mv for 1 tool % of n-butane in a 1.0-~tL sample. 5.1.2 Sample Inlet System, Liquid--A liquid sampling valve shall be provided, capable of entrapping a fixed volume of sample at a pressure at least 200 psi (1379 kPa) above the vapor pressure of the sample at valve temperature, and introducing this fixed volume into the carder gas stream ahead of the analyzing column. The fixed sample volume should not exceed 1.0 IxL and should be reproducible such that successive runs agree within +2 % on each component peak area. The liquid sampling valve is mounted exterior of any type heated compartment and thus can operate at laboratory ambient conditions. 5.1.3 Sample Inlet System, Gas (Instrument Linearity)-Provision is to be made to introduce a gas phase sample into the carder gas stream ahead of the chromatographic column so that linearity of the instrument can be estimated from response curves. The fixed volume loop in the gas sample valve shall be sized to deliver a total molar volume approximately equal to that delivered by the liquid sample valve in accordance with 5.1.2. (See Section 6 for further explanation of instrument linearity check procedures.) 5.1.4 Chromatographic Columns: 5.1.4.1 Column No. I - - A partition column shall be provided capable of separating nitrogen/air, carbon dioxide, and the hydrocarbons methane through normal hexane. (See Figs. 1 and 2.) Separation of carbon dioxide shall be sufficient so that a 1-~tL sample containing 0.01 tool % carbon dioxide will produce a measurable peak on the chromatogram, (The silicone 200/500 column, containing a 27 to 30 weight % liquid phase load, has proven satisfactory for this type of analysis.) 5.1.4.2 Column No. 2--A partition column similar to Column No. 1. It shall be of the same diameter as Column No. 1. The column shall be of an appropriate length to deafly separate the heptanes plus fraction from the hexanes and lighter components. 5.1.5 Attenuator--A multistep device shall be included in the detector output circuitry to attenuate the signal from the detector to the recorder when using manual calculation methods. The attenuation between steps shall be accurate to -+0.5 %. 5.1.6 Temperature Control--The chromatographic column(s) and the detector shall be maintained at their respective temperatures, constant to -+0.3"C during the course of the sample and corresponding reference standard runs. 5.2 Carrier Gas--Pressure-reducing and control devices to give repeatable flow rates. 5.3 Recorder--A strip chart recorder with a full-scale range of I m v shall be required when using manual calculation methods. A m a x i m u m pen response time of I s and a minimum chart speed of I cm/min (0.5 in./min accepted) shallbc required. Faster speeds up to I0 cm/min (3 in./min accepted) are required if the chromatogram is to be interpreted using manual methods to obtain areas. 393
~ c,~lt *AIR ~s~
r~OATING
.¢,.itF
~
D 2597
C~mtl *At ro o~u~
interest. Specifically, components such as CO2 or aromatic hydrocarbons are partially soluble in many displacement liquids and thus can compromise the final analysis. This caution is of the utmost importance and should be investigated prior to utilizing this technique.
~
.ft.,t, u¢.¢~t¢,~.l~
6. Calibration
FIG. 3 RepressuringSystem and ChromatographicValvingwith Floating PistonCylinder NOTE 2--A strip chart recorder is recommended for monitoring the progress of the analysis if an electronic digital integrator without plotting capability is in service. 5.4 Electronic Digital Integrator--A strongly preferred and recommended device for determining peak areas. This device offers the highest degree of precision and operator convenience. NOTE 3: C~ution--Electronic digital integrators are able to integrate peak areas by means of several different methods employing various correction adjustments. The operator should be well versed in integrator operation, preventing improper handling and manipulation of data-ultimately resulting in false information. 5.5 Ball and Disk Integrator--An alternative device in the absence of an electronic digital integrator for determining
peak areas. This device gives more precise areas than manual methods and saves operator time in interpreting the chromatogram. 5.6 Manometer--Well type, equipped with an accurately graduated and easily readable scale covering the range from 0 to 900 m m of mercury. The manometer is required in order to charge partial pressure samples of pure hydrocarbons when determining response curves for linearity checks when using the gas sampling valve. 5.7 Vacuum Pump---Shall have the capability of producing a vacuum of 0.I m m of mercury absolute or less. Required for linearity checks when using the gas sampling valve. 5.8 Sample Filter--An optional device to protect the liquid sampling valve from scoring due to the presence of foreign contaminates such as metal shavings, dirt, etc., in a natural gas liquid (NGL) sample. The filter can be of a small total volume, or an in-line type design and contain a replaceable/disposable element. NOTE 4: Caution--A filter can introduce error if not handled properly. The filter should be clean and free of any residual product from previous samples so that a buildup of heavy end hydrocarbon components does not result. (Can be accomplished by a heating/cooling process or inert gas purge, etc.) The filter element should be 15-pm size or larger so that during the purging process NGL is not flashed, preventing fractionation and bubble formation. 5.9 Sample Containers: 5.9.1 FloatingPiston Cylinder--A strongly preferred and recommended device suitable for securing, containing, and transferring samples into a liquid sample valve and which preserves the integrity of the sample. (See Fig. 3.) 5.9.2 Double-ValveDisplacement Cylinder--An alternate device used in the absence of a floating piston cylinder suitable for securing, containing, and transferring samples into a liquid sample valve. (See Figs. 4 and 5.)
6.1 In conjunction with a calibration on any specific chromatography, the linear range of the components of interest shall be determined. The linearity is established for any new chromatograph and reestablished whenever the instrument has undergone a major change (that is, replaced detectors, increased sample size, switched column size, or dramatically modified run parameters). 6.1.1 The preferred and more exacting procedure is to prepare response curves. The procedure for developing the
data necessary to construct these response curves for all components nitrogen through n-pentane is set forth in Annex A2. 6.1.2 A second procedure utilizes gravimctdcaUy constructed standards of a higher concentration than is conmined in the unknown. A set of response factors arc first determined for all components by means of a blend mix. (See 6.3.) A second (or third) gravimetrically determined standard (either purity or blend) can then be run, using the originally obtained response factors,which contain a concentration of individual components exceeding the expected amounts in the unknowns. W h e n both (or all three) runs match their respective standards within the precision guidelines allowed in Section I0, then the instrument can bc considered linear within that range. NOTE 6--This test method omits the need of a gas sample valve on the chromatographic instrument. However, several accurate primary VENT PRESSURE REGULATOR
?
NE~Le @ ~ ~kJ..V[
NEELLE ~ VENT VAL'¢E~J CHROMATOGRAPH LIQUIO SAMPLING VALVE CYLINDER / ' OUTPUT VALtre ~
~.~q.IND[III | I GLYCOl. • OR I. wATrn
-_LAYffR._~ -,__.~..~...-• GLYCOt. : • OR .
CY~IN[H[R
NEEOLEVALVE ~ " ~~
NOTe 5: Caution--This container is acceptablewhen the displacement liquiddoes not appreciablyaffectthe compositionofthe sample of 394
I ~ CA~RIEh [ ~ GAS - - - , , r i~ ~ l ¢ ~ ~ CARRIER GAS TO CuLJMh
~
~--~'~CYUNOER NEEDLE VALVE
FIG. 4 RepressudngSystem and ChromatographicValvingwith Double-ValveDisplacementCylinder
~
D 2597
PRESSURE REGULATOR
.9
INERT GAS
standard composition be similar to the one shown in Table 2, or closely resemble the composition of expected unknowns. This approach is valid for all components that lie within the proven linear range for a specific gas chromatograph. Nffre 7--Check the reference standard for validity when received and periodicallythereafter. Annex AI details one procedure for making the validitycheck.
~ ( ~ NEEDLEVALVE
CYLINO(Rit 1 ;I'UIII
-..._:..
~[.v-coL I
6.3 Using the selected liquid reference standard, obtain a chromatogram as outlined in Section 7. 6.3.1 Determine peak areas (or peak heights) from the chromatogram for all components. These data shall be used to calculate response factors in accordance with 9.1. 6.3.2 Repeat 6.3 through 6.3.1 until a satisfactory check is obtained. Usually two runs will suffice.
!
.' o ~ . I • WATER '
it
.'YLINDER,J
I
1
7. Procedure
7.1 General--In the routine analysis of samples described in the scope of this procedure, it is possible to obtain all components of interest from a single run. Response factors, determined in duplicate runs on a selected reference standard, are used to convert peak areas (or peak heights) of the unknown sample to real percent. 7.2 Apparatus Preparation--With the proper column(s) and liquid sample valve in place, adjust operating conditions to optimize the resultant chromatogram. Using the reference standard, introduce the sample in the following manner. 7.3 Introduction of Sample: 7.3.1 Floating Piston Cylinders--For floating piston cylinders, refer to Fig. 3 and proceed as follows: connect a source of inert gas to Valve A so that pressure can be applied to the sample by means of the floating piston. Apply a pressure not less than 200 psi (1379 kPa) above the vapor pressure of the sample at .the temperature of the sample injection valve. 7.3.2 Thoroughly mix the sample. 7.3.3 Connect the sample end of the cylinder, Valve B, to
...~.~..-- = (D rr
0.90
a~ U ~ 11.
A=
o
0.
o
.10
250
°
c
200
~
(1)
"8 g
:: 15o
K=
(A9.3)
~/1.8 (B + 273) D
(A9.4)
where: B = mean average boiling point, *C, and D = density at 15"C. By custom, either the mid vapor temperature of the fraction or the mid-point of a gas chromatographic distillation of the fraction can be used for the mean average boiling point. In either case the method must be specified. A9.3.3.1 An estimate of the K-factor can be made using Fig. A9.1. A9.3.4 Calculate the correction to be applied to the AET using Eq. A9.5:
095 100 1.00
50 1 05
FIG. A9.1
5.994296 - 0.972546 log P 2663.129 - 95.76 log P
(A9.2)
P = pressure, between 2 and 760 mm Hg. A9.3.2 The equations are correct only for fractions having a Watson K-factor of 12.0 _ 0.2 and boiling between 38 and 37 I*C. The K-factor shall be assumed to be 12 and any effect of K-factor ignored unless there is mutual agreement to the contrary. A9.3.3 If correction is required, calculate the K-factor using Eq A9.4:
aoo
g
!
~°0' E
(A9.1)
Watson Characterization Factor of Petroleum Fractions
equivalent temperatures are to be obtained either from the tables or by computation.
t = - 1.4[K - 12][log(Pa/Po)] (A9.5) where: t = correction, *C, Pa = atmospheric pressure, kPa (ram Hg), and Po = observed pressure, kPa (mm Hg). A9.3.4.1 An estimate of the correction can be made using Fig. A9.2.
A9.3 Calculation A9.3.1 Convert observed vapor temperature to atmospheric equivalent temperature using Eq A9.1.
480
~t~'~ D 2 8 9 2 0.001
0.0001
0.01
0.1
1
10
1
100
+25
I I
+20
m
~Oh-
.~
+15
'--
+10
o c 0
•o
I
100
I I I
+25
Boiling point correction for characterization factor (K)
+2o
Procedure: Add correction read from this chart to normal boiling point (AET)
+15
"~
l
0
E
10
~
.5
-----..~
l
l
l
+10
l
.
~.... 1.~
~"-
-X
~%
+5
12.0
0
.
~-~"
~ ' ~
"o "o
-5
,.-=---.,--.. mmmm n ~
o
f
v
j
c
o
-10 vl
o U
J
/
I
f
I
~ r
-15
f
/
J
f
1"~
I
-20
-15
f
J
f
J
f
-20
f
f f
-25
"~ 0.0001
0.001
0.01
2
5
0.1
2
5
2
1
Observed FIG. A9.2
5
10
2
S
100
2
S Pa
vapor pressure
1
2
I kPa I
5
10
2
5
-25 100
--~
Boiling Point Corrections for K-Factor
A10. PRACTICE FOR PERFORMANCE CHECK AIO.1 Scope A10.1.1 The determination of efficiency can be made at any cut point where samples of two or more adjacent fractions can be analyzed by gas chromatography. Either fresh or stored samples can be analyzed as long as they have been protected from loss by evaporation. The samples must be wide enough that the overlap by GC analysis does not extend beyond the middle of the fraction. Uniform 100*C wide fractions are recommended. The minimum boiling range is 50"C.
AI0.2. Referenced Documents A 10.2.1 ASTM Standards: D2887 Test Method for Boiling Range Distribution of Petroleum Fractions by Gas Chromatography 4 D3710 Test Method for Boiling Range Distribution of Gasoline and Gasoline Fractions by Gas Chromatography 4
A10.3 Significance and Use
achieved under a variety of conditions because efficiency has no measurable effect on yields except at the beginning and end of a distillation. However, fractions produced at high efficiency will have a narrower boiling range and hence some different properties than the same fraction made at low efficiency. Similarly, concentrations of aromatics, for instance, will be sharpened by high efficiency but are largely unnoticed at lower levels. In order to arrive at a standard level of efficiency, the following overall check is recommended in place of Annexes A1 through A5 inclusive and Annex A7. Calibrations prescribed in Annex A6 should be done routinely. If the results of this test (Annex A 10) are unacceptable, then the foregoing annexes should be considered to determine the cause. A 10.3.2 A precise method for the calculation of efficiency at a cut point has been developed ~° and must be used in cases of dispute. A graphical solution by this method is included in Fig. AI0.1.
l o Butler and Pasternak, 42, 1964, p. 47.
AI0.3.1 Good agreement in yield of fractions can be
481
The Canadian Journal of Chemical Engineering, Vol
D 2892
~)
k--" L,~
(.;
C~
k" L~ T
k,-
,¢
•1 0
#O
4¢
fo
4,.0
70
CROSS CONTAMINATIONON CRUDE, mass-% FIG. A10.1
Efficiency Calculation
A10.4 Summary of Practice
Agreement must be as close as practical using steps of 0.5°C and interpolating where necessary. A 10.6. I. l The example uses excerpts from the following gas chromatographic analysis.
A10.4.1 The cross contamination between the adjacent fractions is calculated as the temperature at which the overlaps are equal on the basis of mass-percent of the charge. This is an empirical method and is done by trial and error to an accuracy of 0.5°C.
A10.5 Procedure AI0.5.1 Obtain samples of at least two contiguous fractions from each level of pressure and analyze them according to Test Methods D 2887 or D 3710, whichever is appropriate. Ensure that temperatures are printed in °C for every 1% from 0 to 100 %. Obtain the yield of each fraction in mass-percent of the crude oil charged to the distillation.
A10.6 Calculation A10.6.1 Select a temperature at the end of Fraction 1 which when converted to yield in mass-percent of the charge will approximate the yield in mass percent of the charge of the front end of the next cut at the same temperature.
482
% by D 2887 Fraction I
BP'C (C4-93"C)
85 86 87 88 89 90
91 92 93 93 95 96
Fraction 2
(93-149"C)
10 11 12 13 14 15
91 92 93 94 94 95
85 86 87 88 89 90
148 149 150 151 152 152
6.5 Weight % on Crude Cut point 93"C 100 - 87.5 = 12.5 % o n c u t 12.5 × 0.065 = 0.813 % on crude
6.8 Weight % on Crude Cut point 93 12.0 × 0.068 = 0.816 on crude + 0.813 C = 1.629 %
Cut point 151.5"C 1 0 0 - 88.5 = 11.5 % o n 11.5 × 0.068 = 0.781%
cut on crude
D 2892 Efficiency Standard 15/5 for Crudes from 25-40 °
TABLE A10.1
API (tentative) Cut Point °C
Standard Efficiency Theoretical Plates
50 100 150 200 250 300 350
5.4 5.5 5.6 6.2 6.8 7.7 9.0
Fraction 3
(149-204"C)
5 6 7 8 9 I0
147 149
+ + + + + + +
1.0 0.9 0.8 0.9 0.9 1.1 1.5
-
0.6 0.8 0.7 0.8 0.6 0.9 1.2
9.4 Weight % on Crude z
150 151 ~i 152 J 153
Cut point 151.5"C 8.5 x 0.094 = 0.799 % on crude + 0.781 C = 1.580 %
~P
AI0.6.1.2 In the above example, the heavy end contamination (tail) of Fraction 1 is 0.813 mass-% at 93°C. Similarly, the light end contamination (leader) of Fraction 2 is 0.816 mass-% and the cut point is 93°C. AI0.6.1.3 Performing the same calculation on cuts 2 and 3, the sum of the contamination is 1.580 mass-% and the cut point 151.5°C. A 10.6.2 Calculate the efficiency at each cut point.
CROSS CONTAHINATION OH CRUDE, mass-g FIG. A10.2
T + 273 n =
48 S
Efficiency Nomograph
(AI0.I)
purposes. A 10.6.3 The following table defines the acceptable limits for efficiency in the performance of a standard distillation. A10.6.4 These limits will be reviewed from time to time and may be adjusted. Fig. AI0.3 is a graph of the limits shown.
where: n = efficiency in theoretical plates, T = cut point, °C, and S = sum of contamination. A10.6.2.1 A graphical solution to equation AI0.1 is shown in Fig. A I0.2 and is sufficiently accurate for practical
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reepproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration st a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohockan, PA 19428.
483
(~l~ Designation: D 3054 - 95 Standard Test Methods for Analysis of Cyclohexane by Gas Chromatography 1 This standard is issued under the fixed designation D 3054; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
procedure is used when the impurities are at 0.00010 to 0.1000 wt% levels. A known amount of internal standard is added to the sample. A portion of the sample is injected into the chromatograph and the levels of impurities are calculated relative to the amount of internal standard added. The amount of all impurities, including benzene, is subtracted from 100.00 to establish the purity of the cyclohexane samples. 3.2 Test Method B: Straight Normalization Procedure--A portion of the sample is injected into the chromatograph using a microlitre syringe at the specified conditions of the test method. The area of all the peaks and main component are electronically integrated. These areas are normalized to 100.00 %.
1. Scope 1.1 These test methods cover the determination of the hydrocarbon impurities typically found in cyclohexane and the purity of cyclohexane by difference by gas chromatography. The absolute purity of cyclohexane cannot be determined, since trace quantities of unknowns may be present. Typical impurities in high purity cyclohexane are listed in Table 1. 1.2 These test methods are applicable to impurity concentrations in the range of 0.0001 to 0.1000 wt% and for cyclohexane purities of 98 % or higher when using the internal standard procedure. 1.3 The following applies to all specified limits in this test method: for purposes of determining conformance with this test method, an observed value or a calculated value shall be rounded off to the nearest unit in the last right-hand digit used in expressing the specification limit, in accordance with the rounding-off method of Practice E 29. 1.4 This standard does not purport to address all of the ~'afi,ty concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Note 2 and Section 7.
4. Significance and Use 4.1 These test methods are suitable for establishing contract specifications on cyclohexane and for use in internal quality control where cyclohexane is either produced or used in a manufacturing process. They may also be used in development or research work. TABLE 1
Impurities Known or Suggested to be Present in Commercial Cyclohexane
2. Referenced Documents 2.1 A S T M Standards: D 3437 Practice for Sampling and Handling Liquid Cyclic Products 2 E 29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications3 E 260 Practice for Packed Column Gas Chromatography 3 E 691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method 3 E 1510 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs 3 2.2 Other Document: OSHA Regulations, 29 CFR, Paragraphs 1910.1000 and 1910.12004 3. Summary of Test Methods 3.1 Test Method A: Internal Standard Procedure--This i These test methods are under the jurisdiction of ASTM Committee !)-16 on Aromatic Hydrocarbons and Related Chemicals and are the direct responsibility of Subcommittee DI6.0A on Benzene, Toluene, Xylenes, Cyclohexane, and Their Derivatives. Current edition approved Sept. 15, 1995. Published November 1995. Originally published as D 3054 - 93. Last previous edition D 3054 - 93 ~. 2 Annual Book of ASTM Standards, Vol 06.04. 3 Annual Book of ASTM Standards, Vol 14.02. 4 Available from Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20004.
C4 (1) n-butane (2) isobutane C6 (3) n-pontane (4) isopontane (5) cyclopentane Ce (6) n-hexaneA (7) 2-methylpentane (8) 3-methylpentane (9) methylcyclopentane 'l (10) benzeneA (11) 2,2-dimethylbutane (12) 2,3-dimethylbutane C7 (13) 3,3-dimethylpentane (14) 2,3-dlmethylpentane (15) 1,1-dimethylcydopentane (16) 1,t3.dimethylcyclopentane (17) 1,t2-dimethylcyclopentane (18) 1 ,c2-dimetbylcyclopontane (19) 2,2-dlmethyipentane (20) 2,4-dimethyipentene (21) 1,c3-dimethylcyclopentane (22) ethylcyclopentane (23) methylcyclohexaneA (24) 3-ethylpentane (25) 3-methylhexane (26) 2-methylhexane (27) n-heptane A These components were used to prepare the standards used in the round robin progrsm.
484
~1~ D 3054 TABLE 2
umn is a methyl silicone-fused silica capillary column. Any other column used must be capable of resolving all significant impurities from cyclohexane. The internal standard peak must be individually resolved without interference from cyclohexane or any other impurities. A typical chromategram with the identified impurities is found in Fig. 1. 5.2.1 Cross.Linked Methyl Silicone Fused Silica Capillary Column, 60 m by 0.50 Ixm film thickness by 0.32 mm diameter• 5.3 Integrator or Data Handling System--Electronic or equivalent equipment for obtaining peak areas. This device must integrate areas at a rate of 15 readings per second so that very narrow peaks resulting from fused silica capillary columns can be accurately measured. 5.4 Microsyringes, capacities 1.0 or I0 I~L, and 50 pL. 5.5 Volumetric Flasks, 100-mL capacity.
Typical Instrument Conditions for Cyclohexane Analysis (See Chromatogram Fig. 1)
Instrument: Range Attenuation inlet, *C Detector, *C Sample size, I~L Column: Carrier gas Linear velocity, cm/sec Split ratio Tubing Stationary phase Solid support Film thickness, p.m Length, m Inside diameter, mm Temperature Program: Initial, *C Time, rain Rate No. 1, *C/min Intermediate, *C Time, mln Rate No. 2, *C/rain Final, *C Time, mln Internal Standard: 2,2.Dlmethylbutane
3 1 200 275 1.2 helium 20.0 45:1 fused silica methyl silicone cross-linked 0.50 60 0.32 32 6 5 52 5 20 230 9
6. Reagents and Materials 6.1 2,2-Dimethylbutane, 99.0 % minimum purity (internal standard). 6.2 Helium. 6.3 Hydrogen and Air, for FID detector. 7. Hazards 7.1 Consult current OSHA regulations, suppliers' Material Safety Data Sheets (MSDS), and local regulations for all materials used in this test method.
NOTE l--In case of dispute, the internal standard procedure will be the correct procedure to use.
5. Apparatus 5.1 Gas Chromatograph (GC) (for a Fused Silica Column)--A multi-ramp temperature, programmable GC built for capillary column chromatography. It must have a flame ionization detector and a split injection system that will not discriminate over the boiling range of the samples analyzed. 5.1.1 Gas Chromatograph--Any chromatograph having a flame ionization detector that can be operated at the conditions given in Table 2. The system should have sufficient sensitivity to obtain a minimum peak height response for a 0.0001 wt% impurity twice the height of the signal background noise. 5.2 Chromatographic Column--The recommended col-
8. Sampling 8.1 Take samples in accordance with Practice D 3437. 9. Procedures 9.1 Test Method A: 9.1.1 Internal Standard Procedure--Install the chromatographic column and establish stable instrument operation at the proper operating conditions shown in Table 2. The selected column and conditions must satisfy the resolution requirements as stated in 5.2. Make reference to instructions provided by the manufacturer of the chromatograph, and to Practices E 260 and E 1510.
1 ;
| ~°nn
i
I! m 0.00 RT tn L t n u t u
I1.•
I
!
7.N
W.W
•
ULN
!
~S.(IO
ASTN IP8054 ROUNDROB~ SkqaLE: SX 110-4437 ~¢JECTED AT f3:Oe:OSONNOV SO, t880 Neth: I)3054 Flare. R~.i04 Pro¢ P~.i04 FIG. 1
Sample 110-4437
485
!
~.m
n.W
~) O 3054 TABLE 3
9.1.2 Place 50 to 60 mL of the cyclohexane sample to be analyzed into a 100-mL volumetric flask. Accurately add, using a micropipet or microsyringe, 25 ~tL of the internal standard to the flask and then fill to the calibration mark with additional sample. Based on using 2,2-dimethylbutane as the internal standard with a density of 0.649 g/mL and cyclohexane with a density of 0.780 g/mL, the concentration of the internal standard will be 0.021 wt%. Similar calculations must be made for any alternative internal standard that may be used. Mix the above, blend thoroughly, and analyze using the chromatographic conditions stated in Table 2. 9.2 Test Method B: 9.2.1 Straight Normalization ProcedureDProceed as in 9.1.1. Then, inject a proper specimen size directly into the gas chromatograph. Integrate all peaks, impurities, and cyclohexane. NOTE 2: Caution--A smaller specimen size might be required so as
Intermediate Precision (Formerly Called Repeatability) and Reproducibility A Intemel Standard Method
Component
AverageExpected Reported Intermediate ReproducConcentration Concentration Precision ibility wt% wt%
Purity
not to exceed the dynamic range of the instrument used.
99.9755 99.7866
99.8753 99.7820
0.0005 0.0034
0.0012 0.0160
n-Hexane
0,0050 0.0207
0.0050 0.0190
0.0001 0.0004
0,0003 0.0012
n-Heptane
0.0049 0.0208
0.0050 0.0212
0.0002 0.0004
0.0004 0.0013
Methyl cyclopentane
0.0047 0.0208
0,0049 0.0221
0.0001 0.0004
0,0004 0.0017
Benzene
0.0010 0.0507
0.0009 0.0532
0.0001 0.0014
0.0003 0.0086
Methylcyclohexene
0.0089 0.1004
0.0089 0,1025
0.0004 0.0031
0.0010 0.0134
,* Outliars removed from data.
10. Calculation
10.1 Calculation for Internal Standard Procedure: 10.1.1 Determine the response factor for each impurity relative to the internal standard by measuring the area under each peak and calculate as follows:
(A,XC,)
R~ = ~ (c,.) (A,)
A~ -- integrated area for impurity peak "i", and A2 = total integrated areas of all peaks. 12. Report 12. l Report the following information: 12.l.1 The cyclohexane purity of the sample to the nearest 0.01 wt%. 12.1.2 The amount of each impurity in the sample to the nearest 0.0001 wt% for the Internal Standard Procedure and to the nearest 0.0010 wt% for the Straight Normalization Procedure.
(1)
where: R; = response factor for impurity, i, relative to the internal standard, Ai = peak area of impurity, i, A~.= peak area of internal standard, Cs = concentration of the internal standard, and C; = concentration of impurity, i, as calculated in 9.1.2. 10.1.1.1 Calculate the impurities as follows: C~ =
(A,)(R,)(C,) (A,)
13. Precision and Bias s
13.1 PrecisionmThe following criteria should be used to judge the acceptability (95 % probability level) of results obtained by this test procedure. The criteria were derived from an interlaboratory study among seven participating laboratories. The data were determined on two days using different operators and using two samples. The samples were gravimetrically prepared from recrystallized cyclohexane and the individual hydrocarbon impurities to the concentrations listed in Tables 3 and 4. The results of the interlaboratory study were calculated and analyzed using Practice E 69 I. 13.l.l Results in the same laboratory should not be considered suspect unless they differ by more than the amount shown in Table 3 and Table 4. On the basis of test error alone, the difference between two test results obtained in the same laboratory on the same material will be expected to exceed this value only 5 % of the time. 13.1.2 Results obtained by each of two laboratories should not be considered suspect unless they differ by more than the amount shown in Table 3 and Table 4. On the basis of test error alone, the difference between two test results obtained in different laboratories on the same material will be expected to exceed this value only 5 % of the time. 13.2 Bias--Although the interlaboratory test utilized a sample prepared gravimetrically from chemicals obtained at
(2)
and: 10.1.2 Calculate the total concentration of impurities as follows:
C,=ZC,., where: C, = total concentration of all impurities, weight %. 10.1.3 Cyclohexane Purity by Difference (Weight PercenO: Cyclohexane, % = 100.00 - Ct (3) NOTE 4--First, convert total impurities to weight percent and then subtract from 100. 10.2 Calculation for Straight Normalization Procedure: NOTE 5--Detector response factorshave been establishedto be equal to unity; therefore, area percent is equivalent to weight percent. 10.2.1 Area Percent Cyclohexane: Cyclohexane, % = (A dA2) x 100 (4) where: A I = integrated area of cyclohexane, and A2 = total integrated areas of all peaks. 10.2.2 Area Percent Impurities:
impurity-i,
% -- (AI/A2) X 100
s Supporting data are available from ASTM Headquarters. Request RR: DI6-1016.
(5)
where: 486
(!~ D 3054 TABLE 4
the highest purity available, these samples have not been approved as an acceptable reference material and consequently bias has not been determined. 13.2.1 As an aid for the users in determining the possibility of bias, the calculated concentration of each impurity in the two round robin samples is listed in Tables 3 and 4 as the "expected concentration." The average value for each impurity as reported from the six participating laboratories is listed as "average concentration reported."
Intermediate Precision (Formerly Called Repeatability) and Reproducibility A Straight Normalization Method Expected AverageConcentration Reported Intermediate ReproducConcentration Precision ibility wt % wt~
Component
Purity
99.9755 99.7877
99.9766 99.7877
0.0016 0.0118
0.0063 0.0264
n-Hexane
0.0050 0.0207
0.0048 0.0190
0.0003 0.0023
0.0011 0,0039
n-Heptane
0.0049 0,0208
0.0048 0.0206
0.0002 0.0016
0.0007 0.0020
Methylcyclopentane
0.0047 0.0208
0.0045 0.0209
0.0003 0.0022
0.0013 0.0033
Benzene
0.0010 0.0507
0.0006 0.0508
0.0005 0.0023
0.0018 0.0089
Methylcyclohexane
0,0089 0.1004
0.0087 0.1010
0.0003 0.0033
0.0013 0.0084
14. Keywords
14.1 cyclohexane; gas chromatography; impurities
A Outliers removed from data.
The American Society for Testing and Materials takes no position respecting the vafidity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reepproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at e meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
487
(~~I~1~ Designation:D 3120 - 96
An American National Standard
Standard Test Method for Trace Quantities of Sulfur in Light Liquid Petroleum Hydrocarbons by Oxidative Microcoulometry 1 This standard is issued under the fixed designation D 3120; the number immediately following the designation indicates the year of original adoption or, in the ease of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 This test method covers the determination of sulfur in the range from 3.0 to 100 ppm (~tg/g) in light liquid hydrocarbons boiling in the range from 26 to 274°C (80 to 525"F). 1.2 This test method may be extended to liquid materials with higher sulfur concentrations by appropriate dilution. 1.3 The preferred units are micrograms per grams. Values stated in SI units are to be regarded as the standard. Values in inch-pound units are for information only. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see 6.3, 6.4, 6.8, and 6.10.
the process. Higher concentrations of sulfur in products analyzed by this test method after appropriate dilution are often detrimental to the use of the product. 4. Interferences 4.1 This test method is applicable in the presence of total halide concentrations of up to 10 times the sulfur level and total nitrogen concentrations of up to 1000 times the sulfur level. 4.2 This test method is not applicable in the presence of total heavy metal concentrations (for example, Ni, V, Pb, etc.) in excess of 500 ~g/g (ppm). NOTE I - - T o attain the quantitative detectability that the method is capable of, stringent techniques must be employed and all possible s o u r c e s o f sulfur contamination must be eliminated.
5. Apparatus 2 5.1 Pyrolysis Furnace--The sample should be pyrolyzed in an electric furnace having at least two separate and independently controlled temperature zones, the first being an inlet section that can maintain a temperature sufficient to volatilize all the organic sample. The second zone shall be a pyrolysis section that can maintain a temperature sufficient to pyrolyze the organic matrix and oxidize all the organically bound sulfur. A third outlet temperature zone is optional. 5.1.1 Pyrolysis furnace temperature zones for light liquid petroleum hydrocarbons should be variable as follows:
2. Summary of Test Method 2.1 A liquid sample is injected into a combustion tube maintained at about 800°C having a flowing stream of gas containing about 80 % oxygen and 20 % inert gas (for example, nitrogen, argon, etc.). Oxidative pyrolysis converts the sulfur to sulfur dioxide which then flows into a titration cell where it reacts with triiodide ion present in the electrolyte. The triiodide thus consumed, is coulometrically replaced and the total current required to replace it is a measure of the sulfur present in the sample injected. 2.2 The reaction occurring in the titration cell as sulfur dioxide enters is:
Inlet zone Center pyrolysis zone Outlet zone (optional)
13- + S O 2 + H 2 0 ---} SO 3 + 31- + 2H +
up to at least 700"C 800 to 1000"C up to at least 800"C
5.2 Pyrolysis Tube, fabricated from quartz and constructed in such a way that a sample, which is vaporized completely in the inlet section, is swept into the pyrolysis zone by an inert gas where it mixes with oxygen and is burned. The inlet end of the tube shall hold a septum for syringe entry of the sample and side arms for the introduction of oxygen and inert gases. The center or pyrolysis section should be of sufficient volume to ensure complete pyrolysis of the sample. 5.3 Titration Cell, containing a sensor-reference pair of electrodes to detect changes in triiodide ion concentration and a generator anode-cathode pair of electrodes to maintain constant triiodide ion concentration and an inlet for a
The triiodide ion consumed in the above reaction is generated coulometrically thus: 3I- --, 13- + 2e2.3 These microequivalents of triiodide (iodine) are equal to the number of microequivalents of titratable sample ion entering the titration cell. 3. Significance and Use 3.1 This test method is used to determine trace quantities of sulfur in reformer charge stocks and similar petroleum fractions where such trace concentrations of sulfur are deleterious to the performance and life of the catalyst used in
2The apparatus described in Sections 5.1 to 5.5 inclusive, is similar in specifications to equipment available from Dohrmann Div. of Rosemount, 3240 Scott Blvd., Santa Clara, CA 95050. For further detailed discussions, in equipment, see: Preprints--Division of Petroleum Chemistry, American Chemical Society, Vol I, No. 3, Sept. 7-12, 1969, p. B232 "Determination of Sulfur, Nitrogen, and Chlorine in Petroleum by Microcoulometry," by Harry V. Drusbel.
This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.03 on Elemental Analysis. Current edition approved Apr. 10, 1996. Published June 1996. Originally published as D 3120 - 72 T. Last previous edition D 3120 - 92.
488
o a12o NOTE 6: Warning--Compressed gas under high pressure. Gas reduces oxygen available for breathing.
gaseous sample from the pyrolysis tube. The sensor electrode shall be platinum foil and reference electrode platinum wire in saturated triiodide half-cell. The generator anode and cathode half-cell shall also be platinum. The titration cell shall require mixing, which can be accomplished through the use of a magnetic stirring bar, stream of inert gas, or other suitable means.
6.5 Cell Electrolyte Solution--Dissolve 0.5 g of potassium iodide (KI) and 0.6 g of sodium azide (NAN3) in approximately 500 mL of high-purity water, add 5 mL of acetic acid (CH3COOH) and dilute to 1000 mL. NOTE 7--Bulk quantities of the electrolyte should be stored in a dark bottle or in a dark place and be prepared fresh at least every 3 months.
NOTE 2: Caution--Excessive speed will decouple the stirring bar, causing it to rise in the cell and damage the electrodes. The creation of a slight vortex is adequate.
5.4 Microcoulometer, having variable attenuation, gain control, and capable of measuring the potential of the sensing-reference electrode pair, and comparing this potential with a bias potential, amplifying the potential difference, and applying the amplified difference to the working-auxiliary electrode pair so as to generate a titrant. Also the microcoulometer output voltage signal shall be proportional to the generating current. 5.5 Recorder, having a sensitivity of at least 0.1 mV/in. with chart speeds of 1/2 to 1 in./min. Use of a suitable electronic or mechanical integrator is recommended but optional. 5.6 Sampling SyringemA microlitre syringe of 10-~tL capacity capable of accurately delivering 1 to I0 ktL of sample into the pyrolysis tube. 3-in. by 24-gage needles are recommended to reach the inlet zone of the pyrolysis furnace. NOTE 3--Since care must be taken not to overload the pyrolyzing capacity of the tube by too fast a sample injection rate, means should be
6.9 n-Butyl Sulfide (CH3CH2CH2CH2)2S. 6. l0 Oxygen, high purity grade (HP), 4 used as the reactant gas. NOTE 10: Warning--Oxygen vigorously accelerates combustion.
6. l 1 Potassium Iodide (KI), fine granular. 6.12 Sodium Azide (NaN3), fine granular. NOTE l l: Warning--Toxic, causes eye and skin irritation; explosive.
6.13 Sulfur, Standard Solution (approximately 30 ~tg/g (ppm))--Pipet l0 mL of sulfur stock solution (reagent 6.14) into a 100-mL volumetric flask and dilute to volume with isooctane.
provided for controlling the sample addition rate (0.1 to 0.2 laL/s).
6. Reagents and Materials 6. l Purity of Reagents--Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available) Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 6.2 Purity of Water--The water used in preparing the cell electrolyte should be demineralized or distilled or both. Water of high purity is essential.
NOTE 12--The analyst may choose other sulfur compounds for standards appropriate to sample boiling range and sulfur type which cover the concentration range of sulfur expected.
6.14 Sulfur, Standard Stock Solution (approximately 300 Ixg/g (ppm))mWeigh accurately 0.5000 g of n-butyl sulfide into a tared 500-mL volumetric flask. Dilute to the mark with isooctane and reweigh. S, ppm (p.g/g) = g of n-butyl sulfide x 0.2187 x l06 g of (n-butyl sulfide + solvent)
7. Preparation of Apparatus 7.1 Carefully insert the quartz pyrolysis tube in the pyrolysis furnace and connect the reactant and carrier gas lines. 7.2 Add the electrolyte solution to the titration cell and flush several times. Maintain an electrolyte level of I/8 to I/4 in. (3.2 to 6.4 mm) above the platinum electrodes. 7.3 Place the heating tape on the inlet of the titration cell. 7.4 Position the platinum foil electrodes (mounted on the moveable cell head) so that the gas inlet flow is parallel to the electrodes with the generator anode adjacent to the generator cathode. Assemble and connect the coulometer and recorder (integrator optional) as designed or in accordance with the manufacturer's instructions. Figure X I.2 illustrates the typ-
NOXE4--Distilled water obtained from an all borosilicate glass still, fed from a demineralizer, has proven very satisfactory. 6.3 Acetic Acid (rel dens (CH3COOH).
6.6 Gas Regulators--Two-stage gas regulators must be used on the reactant and carrier gas. 6.7 Iodine (I), 20 mesh or less, for saturated reference electrode. 6.8 Isooctane 5 (2,2,4-trimethylpentane). NOTE 8: Warning--Extremely flammable. Harmful if inhaled. Vapors may cause flash fire. NOTE 9--The most reliable solvent is a sulfur-freeform of the sample type to be analyzed. Alternatively,use a high-purity form ofcyclohexane [boiling point 80"C (176"F)], isooctane (2,2,4-trimethyl pentane) [boiling point, 99.3"C (211*F)], or hexadecane [boiling point, 287.5"C (549.5"F)].
1.05)--Glacial acetic acid
NOTE 5: Warning--Poison. Corrosive. Combustible. May be fatal if swallowed. Causes severe burns. Harmful if inhaled. 6.4 Argon, Helium, or Nitrogen, high purity grade (HP), 4 used as carrier gas. 3 Reagent Chemicals, American Chemical Soctety Specificattons, American Chemical Society, Washington, DC. For suggestionson the testing of reagents not listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the Umted States Pharmacopeia and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD. 4 High-purity grade gas has a minimum purity of 99.995 %.
s Pesticide test grade such as Mallinckrodt "Nano-grade'" isooctane has been found satisfactory.
489
~
D 3120
100 - -
95--
90 n
\
\ \
85--
E~
\ t~
\
80--
\
\
\
75--
\
70 m
65
..-42 ~E}.___
__.El_-
j
l
I
l
i
I
I
I
700
750
800
850
900
950
1000
Center FurnaceTemperature(°C)
Oxidative sulfur system: Thiophene in cyclohexane(10 ppm S) using 0.06~ aside electrolyte Flow rate (cc/min) Legend
®
Q
El----El ,~, FIG. 1
&
Oxygen
Argon
O2/Ar ratio
40
16o
1:4
lOO
lOO
,:,
160
,0
4:1
Percent Recovery versus Temperature (°C)
ical assembly and gas flow through a coulometric apparatus. 7.4.1 Turn the heating tape on. 7.5 Adjust the flow of the gases, the pyrolysis furnace temperature, titration cell, and the coulometer to the desired operating conditions. Typical operational conditions are given in Table I.
NOTE 13--See Fig. 1 for the variance of percent recoveries with gas ratios and temperature.
8.3 The sample size can be determined either volumetrically or by mass. The sample size should be 80 % or less of the syringe capacity. 8.3. l Volumetric measurement can be obtained by filling the syringe with about 8 ~tL or less of sample, being careful to eliminate bubbles, retracting the plunger so that the lower liquid meniscus falls on the l-~L mark, and recording the volume of liquid in the syringe. After the sample has been injected, again retract the plunger so that the lower liquid meniscus falls on the 1-1zL mark, and record the volume of liquid in the syringe. The difference between the two volume
8. Calibration and Standardization
8.1 Prepare a series of calibration standards covering the range of sulfur concentration expected. Follow instructions in 6.13, 6.14, or dilute to appropriate level with isooctane. 8.2 Adjust the operational parameters (7.5). 490
~ TABLE 1
D 3120 TABLE 2
Typical Operational Conditions
Reactant gas flow (oxygen), cma/min Carder gas flow (At, He, N) cma/min Furnace temperature; oC: Inlet zone Pyrolysis zone Outlet zone Titration cell Coulometer: Bias voltage, mV Gain
160 40
Sample Type Naphthas
700 800 800 set to produce adequate mixing
R M V D F
readings is the volume of sample injected. 8.3.2 Alternatively, the sample injection device may be weighed before and after the injection to determine the amount of sample injected. This technique provides greater precision than the volume delivery method, provided a balance with a precision of +0.00001 g is used. 8.4 Insert the syringe needle through the inlet septum up to the syringe barrel and inject the sample or standard at an even rate not to exceed 0. l to 0.2 ~tL/s. I f a microlitre syringe is used with an automatic injection adapter, the injection rate (volume/pulse) should be calibrated to deliver 0. l to 0.2 ttL/s. 8.5 Repeat the measurement of each calibration standard at least three times.
= = = ffi
Boiling=C Point ('F)Range
Sulfur Compound
26 to 204
cyOohexane sulfide
(80to 400)
Jet fuels and stove oil
160 low (approximately 200)
Satisfactory Standard Materials
177 to 274 (350 to 525)
banzyl-thlophene
coulometer range switch setting, fl, mass of sample, g (volume x density), volume of sample, ttL, density of sample, g/mL, and recovery factor, fraction of sulfur in standard that is titrated, ratio of ppm sulfur determined in standard divided by the known ppm sulfur in standard. F ffi (,4 x 1.99)/(R x M x C=d)
where: concentration of standard, ppm. 10.2 Derivation of the calculation equation will be found in XI.3. Cst d
NOTE 15--The calculation equation is valid only when the chart speed is 0.5 in./min and a 1-mV (span) recorder with a sensitivity of 0.1 mV/in, is used. NOTE 16--If a disk integrator is used, see XI.3 for calculations, derivations, and equations. NOTE 17--A more general form of the equation in 10.1 which is not dependent on the use of a particular recorder scale nor a disk integrator is as follows:
NOTE 14--Nog all of the sulfur in the sample comes through the furnace as titratable SO2. In the strongly oxidative conditions of the pyrolysistube some of the sulfur is also converted to SO3 which does not react with the titrant. Accordingly, sulfur standards of n-butyl sulfide in isooctane or sulfur standards appropriate to sample boiling range and sulfur type and sulfur concentration should be prepared to guarantee adequate standardization. Recoveries less than 75 % are to be considered suspect. Low recoveries are an indication to the operator that he should cheek his parameters, his operating techniques, and his ¢oulometric system. If the instrument is being operated properly, recoveries between 75 and 90 % are to be expected. Satisfactory standard materials6 are given in Table 2.
(A) (X) (0.166)
sulfur, ppm (ttg/g) = (R) (Y) (M) (F) where: A = area in appropriate units, X = recorder sensitivity for full-scale response (mv), 0.166 ffi (16 gS/eq) (10-3 V/mV) (106 txg/g) (96 500 coulombs/eq)
8.6 If the fraction of sulfur converted to SO2 drops below 75 % of the standard solutions, fresh standards should be prepared. If a low conversion factor persists, procedural details should be reviewed.
R = resistance, fl, Y = area equivalence for a full-scale response on the recorder per s e c o n d . . , area units per second, M = mass of sample, g, and F = recovery factor.
9. Procedure 9.1 Flush the 10-ttL syringe several times with the unknown sample. Determine the sulfur concentration in accordance with 8.2 to 8.6. 9.2 Sulfur concentration may require adjustment of sensifixity settings or sample volume or both.
11. Precision and Bias 11.1 The precision of this test method as obtained by statistical examination of interlaboratory test results is as follows: 11.1.1 Repeatability--The difference between successive test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method exceed 28 % of the average value only in one case in twenty. 11.1.2 Reproducibility--The difference between two single and independent results obtained by different operators working in different laboratories on identical test material would, in the long run, in the normal and correct operation of the test method exceed 38 % of the average only in one case in twenty. 11.2 Bias--Since there is no accepted reference material suitable for determining the bias for the procedure in this test
10. Calculation 10.1 Calculate the sulfur content of the sample in parts per million, p p m ~tg/g, by mass as follows: Sulfur, ppm ttg/g ffi (.4 x 1.99)/(R x M x F) (1) Sulfur, ppm = (A X 1.99 x 10a)/(R x V x D x F) (2) where: A = area under curve, in. 2, 1.99 = derivation will be found in X1.3, 6 Wallace, L. D., "Comparison of Oxidative and Reductive Methods for the Microcoulometric Determinations of Sulfur in Hydrocarbons," Analytical Chemistry, Vol 42, March 1970, p. 393.
491
~
D 3120
method, no statement on bias is made. 7
12. Keywords 12.1 light hydrocarbons; microcoulometry; sulfur
7SupportingdataareavailablefromASTM.RequestRR:D02-I036. APPENDIX
(Nonmandatory Information) XI. DERIVATION OF COULOMETRIC CALCULATIONS USED IN SECTION 10.1 X 1.1 The configuration of the pyrolysis tube and furnace may be constructed as is desirable as long as the operating parameters are met. Figure X I. 1 is typical of apparatus currently in use. X I.2 A typical assembly and oxidative gas flow through a coulometdc apparatus for the determination of trace sulfur is shown in Fig. XI.2. X 1.3 Derivation of Equations:
X I.3.1 The derivation of the equations used in the calculation section is based on the coulometric replacement of the tdiodide (iodine) ions consumed in the microcoulometric titration cell reaction (I3- + 2e- -* 3I-. The quantity of the reactant formed (triiodide ions) between the beginning and the interruption of current at the end of the titration is directly proportional to the net charge transferred,
Q. X 1.3.2 In most applications a constant current is used so that the product of current, i, in amperes (coulombs per second), multiplied by the time, T (seconds), required to reach the end point provides a measure of the charge, Q (coulombs), necessary to generate the iodine equivalent to the reactant; that is, Q ffi it. Therefore, the number of equivalents of reactant is equal to Q/F, where F is the Faraday constant, 96 500 C per equivalent. XI.3.3 Therefore, the expression to be solved to find the mass of reactant is:
Furnace Outlet
Center
Inlet
', ,_-=: Carrlt. r (,as A rgon
FIG. X1.1
Pyrolipla Tube
Inlet
Outlet
Sample Injection Z~ne pyz:l::i s Zone
7
I
Titration Cell Potentiometric Recorder
FIG. X1.2
Flow Diagram for Coulometdc Apparatus for Trace Sulfur Determination
492
(~ D 3120 Q(C)
16 g X FC eq eq mass o f sample, g
~
C o n c e n t r a t i o n o f sulfur =
lagS=Ain.
2X
mass o f sulfur, g mass o f sample, g
0.1 m____~Vx 2 min x 60: s x -10 -3 - V x in. in. mm mV R ( a ) x 96 500___ C x ~ eq
= peak area m e a s u r e d in square inches, = millivolt span o f upscale deflection for the recorder, 2 min/in. = chart speed in minutes per inch, 60 s/rain = conversion o f t i m e in m i n u t e s to seconds, 10 -3 V / m V = conversion o f volts to millivolts, 16 g/eq = g r a m - e q u i v a l e n t o f sulfur, 10 6 lag/g = m i c r o g r a m s p e r g r a m conversion factor, R(fl) = m i c r o c o u l o m e t e r range switch setting in ohms, substituting V]R = 1 (amps) A in.Zx Q(A.s) =
10 6
lag
lag S = (A x 1.99)/(R x f )
(Xl.5)
(Xl.6)
Since p p m = lag/g: ppm S =
A x 1.99
R xfx
volume, laL
(XI.7)
x 103 ~-~ x density, m ~L
0.1 mV 2 m i n 60s 10- 3 V x x x - in. in. min mV R(a)
A x 12 x 10-3 × 16 x R x 96 500 x f
Therefore,
A x 1.99 x 103 ppm S = R x f x volume x density (X 1.3)
(XI.8)
Since mass - v o l u m e x density ppm S -- (A x 1.99)/(R x f x
96 500 C/eq F a r a d a y ' s c o n s t a n t s (electrical equivalence o f one g r a m - e q u i v a l e n t mass o f any substance) = conversion o f c o u l o m b s to ampere-seconds, and = recovery factor (ratio o f p p m S d e t e r m i n e d in s t a n d a r d versus k n o w n p p m S in standard)
f
(Xl.2)
x f)
lag S =
=
A" s/C
16 g x -106- lag eq g
Therefore,
where: A in. 2 0.1 m V / i n .
F
(xl.1)
mass, g)
(XI.9)
X I . 3 . 4 Derivation with Disk lntegrator--A in Eq X I.6 is expressed as i n ? However, it m a y also be expressed as counts. Therefore, A in. 2 -- counts x 10 -3 since 1 in. 2 = 1000 counts. Therefore, substituting counts x 10 -3 for A in Eq X 1.6 gives lag S = (counts x 1.99 x 10-3)/(R x f )
Therefore,
Then: ppm S =
A x 12 x 10-3 A . s × 16 g x ~106 lag eq g lag S =
(XI.10)
counts x 1.99
R × volume, laL x density, ~
(X 1.4)
inL
R x 96 500.._.. C x A. s eq ~ ×f
xf
p p m S = (counts x 1.99 x 10-3)/(R x mass, g x f ) NOTE X l . l - - C o u n t s
s The value of the Faraday has been redetermined in 1960 by the National Bureau of Standards: the new value is 96 489 + 2 coulombs (chemical scale).
-- 100 x number o f integrator per full-scale
excursions.
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments wi// receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you fee/that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohocken, PA 19428.
493
(1~]~ Designation:D 3205-86 (Reapproved 1991) Standard Test Method for Viscosity of Asphalt with Cone and Plate Viscometer 1 This standard is issued under the fixed designation D 3205; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an e&tonal change since the last revision or reapproval.
1. Scope 1.1 This test method covers the determination of the viscosity of asphalt cements by means of a cone-plate viscometer. It is applicable to materials having viscosities in the range from 10 3 t o 1010 P (102 to 109 Pa.s) and is therefore suitable for use at temperatures where viscosity is in the range indicated. The shear rate may vary between approximately 10-3 to 102 s-1 and the method is suitable for determination on materials having either Newtonian or non-Newtonian flow properties. 1.2 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
assembly which is then brought to the test temperature. Weights acting through a pulley apply torque to the cone and the angular velocity of the cone is measured. Viscosity in poises and shear rate in reciprocal seconds are calculated from the angular velocity, torque, and calibration constants. 4.2 Some asphalt cements may fracture at shear stresses within the range of this instrument. This fracture stress may be reported.
5. Significance and~Use 5.1 The rheological properties of asphalt cements are used for specification purposes for road pavement construction. The instrument provides measurements over a wide range of temperatures for use in research and development of asphalt cements and other bituminous materials.
2. Referenced Documents 2.1 A S T M Standards: C 670 Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials 2 D 92 Test Method for Flash and Fire Points by Cleveland Open Cup 3
D93 Test Method for Flash Point by Pensky-Martens Closed Cup Tester 3 E 1 Specification for ASTM Thermometers 4
3. Definitions 3.1 viscosity--the resistance to deformation or internal friction of a liquid, expressed as the ratio of shear stress to shear rate, whether this ratio is constant or not. The unit of viscosity obtained by dividing the shearing stress in dynes/ square centimetre by the rate of shear in reciprocal seconds is called the poise. The SI unit of viscosity has the dimensions of pascal-seconds (Pa-s), and is equivalent to 10 P. 3.2 Newtonian liquid a liquid in which the rate of shear is proportional to the shearing stress. 3.3 non-Newtonian liquid a liquid in which the rate of shear is not proportional to the shearing stress. 4. Summary of Method 4.1 The sample is placed between the cone-and-plate t This test method is under the .~unsdiction of ASTM Committee D-4 on Road and Paving Materials and is the direct responsibility of Subcommittee D04.44 on Rheological Tests. Current edition approved Nov. 28, 1986. Published January 1987. Ongmally pubhshed as D 3205 - 73 T. Last previous edttlon D 3205 - 79 (1985). 2 Annual Book of ASTM Standards, Vol 04.02. 3 Annual Book of ASTM Standards, Vol 05.01. 4 Annual Book of ASTM Standards, Vol 14.03.
494
6. Apparatus 6.1 Cone-Plate Viscometer, s'6 as shown in Fig. 1 with metric weights from 10 to 20 000 g. It is used for measuring the viscosities in the range from 103 to 10 I° P (102 to 109 Pa.s) at shear rates from 10 -3 to 10-2 s-l. Important dimensions of each cone and approximate constants are given in Table 1. The approximate data of Table 2 may be helpful in the selection of the proper cone and load. 6.2 Thermometers--Calibrated mercury-in-glass thermometers of suitable range and graduated to 0. I*F (0.05"C). They shall conform to the requirements of Specification E 1. Calibrated ASTM kinematic viscosity thermometers are satisfactory. Other thermometric devices are permissible provided their accuracy, precision, and sensitivity are equal or better than ASTM kinematic viscosity thermometers. 6.3 Bath--A water, alcohol, or ethylene glycol bath suitable for the immersion of the plate and cone and of such height that the cone is immersed to a depth of at least 60 mm. The efficiency of the stirring and balance between heat losses and heat input must be such that the temperature of the water does not vary by more than _.+0.I*F (0.05"C). 6.4 Timer--A stop watch or other timer graduated in divisions of 0.1 s or less and accurate to within 0.01% when tested over intervals of not less than 15 min. Electrical timing devices may be used only on electrical circuits in which frequency is controlled to an accuracy of 0.05 % or better. 6.4.1 Alternating-current frequencies that are intermittently and not continuously controlled, as provided by some 5 Slsko, A. W., "Determination and Treatment of Asphalt Viscosity Data" Highway Research Board, Highway Research Record No. 67, 1965. 6 Manufactured by the Cannon Instrument Co., P.O. Box 16, State College, PA 16801.
(~) D 3205 TABLE 2
MICARTA-~
rrn o1=7 VI=31 I I1 II, / Ik,';'=,,h, ": ..... ,"" ,'""::11 / I "r I
1, 10 -1, and 10 -2 s -1 Cone No. 8
-BRASS
......
2
Angular veloclty,°/s
- ~ hl C O NP'" E I ~SPANNER i
15 24 cm.
=i
NOTE ALL PARTS STAINLESS EXCEPT AS $NOICATED
FIG. 1
Assembly View of Viscometer
public power systems, can cause large errors, particularly over short timing intervals, when used to actuate electrical timing devices. 6.5 O h m m e t e r , or any electrical device capable of indicating that contact between cone and plate is maintained prior to, and during the test.
7. Calibration 7.1 Determine the shear stress constant, K s , the shear rate constant, KD, and the friction correction F, as follows: 7.1.1 To calculate the shear stress constant, K s , proceed as follows: 7.1.1.1 Using an accurate micrometer, measure the cone radius, r (diameter/2) to an accuracy of +_0.05 m m (+0.002 in.). The effective drum radius is the drum radius plus half the string thickness: measure the effective drum radius, R, to an accuracy of +-0.05 m m (+-0.002 in.). Calculate Ks in dynes per (centimetre squared) gram as follows: Ks 3g R/27rr 3 (1) =
where: r = radius of cone, cm, R = effective radius of drum, cm, and g = gravitational constant, 980 dynes/g. 7.1.2 Determine the shear rate constant, K D, for each cone by direct calibration with viscosity standards (see Table TABLE 1
Approximate Instrument Cone Sizes and Constants
Cone No. A
Approximate Cone Radius, cm B
Approximate Cone Angle,
8 4 2
3.75 1.88 0.94
0.5 0.5 05
deg c
Approximate Cone Constant Ks , Ko, deg -1 dynes/cm2.g 2.0 2.0 2.0
100 1000 10000 100 1000 10000 100 1000 10000
4
crn
i
HOLE
Load, g
Approx=mate Viscosities, MP, at Shear Rates of 1 s -1
22
CARDOLOYPLATE -
Approximate Loads and Viscosities at Shear Rates of
495
0.03 0.3 3 0.25 2.5 25 2 2O 200 0.05
0.03 3 30 2.5 25 250 20 200 2000 0.005
(2)
K D = Ks/~m
where: Ks has the value determined in Eq 1, -- viscosity of standard oil, P, and m = slope of regression line resulting from plotting O/t versus L. 7.1.3 Determine the friction correction, F, in grams by one of the following methods: 7.1.3.1 Use the equation: F = L - (1/m)(O/t) (3) where: F = friction correction, g, L = applied load, g, m = slope of the regression line, 0 = measured angle of rotation, deg, and t = measured time of rotation, s. Calculate the value of F for each load point and determine the average. 7.1.3.2 Determine the friction correction F from the plot of 7.1.2 as the intercept with the abscissa.
8. Preparation of Sample 8.1 Heat the sample in an oven at a temperature which is at least 50OF (28°C) below the flash point (Note 1) and in any case not over 3250F (163°C) until it has become sufficiently
Viscosity Standard
A Other cone sizes may be used. a Exact cone and drum redi= must be measured to determine K s by calculation. c Exact cone angle may be calculated from the determination of KD by viscosity standards and measured cone and drum radii. Ko is the reciprocal of the angle between the cone and plate
10 -2 s -1
3 for available calibration standards). This is obtained by the following procedure: 7.1.2.1 Measure the angle of rotation, O, in degrees, and the time, t, in seconds, at applied loads, L, from 5 to 500 g (the range of applied loads will depend on the size of the cone being calibrated). 7.1.2.2 Plot the angular velocity, O/t, in degrees per second, as the ordinate versus the applied load, L, in grams, as the abscissa as shown in the example of Fig. 2. Determine the slope, m, of the line and calculate KD in reciprocal degrees as follows:
TABLE 3
31 250 2000
0.003 0.03 0.3 0.025 0.25 2.5 0.2 2 20 05
1 0 - 1 S- 1
N 30000 A N 190000 A
Viscosity Standards Approximate Viscosity, P At 68°F
At86*F
1500 8000
... ...
A Available in 1-pt containers, price $40.00. F.O.B. State College, PA. Purchase orders should be addressed to Cannon Instrument Co., P.O. Box 16, State College, PA 16804
o a2os i
i
J
]
[
20
40
60
80
I00
10.4 Remove the weight from the top of the shaft. 10.5 Alternative No. / - - M e a s u r e the angular velocity for increasing loads using at least five different weights starting with the smallest and applying them successively at no more than 10-min intervals between each load application. 10.6 Alternative No. 2--Measure angular velocity for decreasing loads using at least five different weights starting with the largest and apply them successively at no more than 10-min intervals between each application. 10.7 Allow the cone to rotate approximately 1° before recording data for each weight. 10.8 The angle of rotation of the cone shall be sufficient to ensure a m i n i m u m time of 20 s, measured to the nearest 0.1 s. While the test is in progress, verify contact between the cone and plate continually or intermittently at frequent intervals, since cone and plate separation may occur as the angle of rotation increases. If contact is lost make the test with a smaller angle of rotation. Select a larger cone and repeat the test starting with 9.3. 10.9 Upon completion of the test, remove the viscometer from the constant-temperature bath. Clean the plate and cone with several rinsings of an appropriate solvent completely miscible with the sample, followed by a completely volatile solvent.
24 c.) L.d
20 (.9 Ld
>:
16
I--
o
12
.J i,i > n.,,
8
< J
4 Z
o
0
WEIGHT, GRAMS FIG.
2
Calibration
of Instrument
fluid to pour, occasionally stirring the sample to aid heat transfer and to assure uniformity. Transfer a m i n i m u m of 200 m L into a suitable container and heat to a temperature of 250 to 300*F (120 to 150"C) (Note 2). After melting thoroughly, stir the sample until it is homogeneous and free of air bubbles. NOTE l - - F l a s h point is defined and determined by either Test Method D 92 or Test Method D 93.
NOTE 2--Sample may be passed through a No. 50 (300-~m) sieve during this transfer.
9. Preparation of Apparatus 9.1 Maintain the bath at test temperature within +0.02*F (0.01*C). Apply the necessary corrections, if any, to all thermometer readings. 9.2 Select the proper size cone to allow measurement of viscosity over a 100-fold shear rate range, preferably at loads of 100, 300, 1000, 3000, and 10 000 g or up to fracture of the sample. (See Table 1 for approximate recommended viscosity ranges for each cone.) 9.3 Place the cone in position in the viscometer, and the plate in place. Tighten the plate firmly, but do not force. 10. Procedure 10.1 Raise the cone and place sufficient hot, prepared sample onto the center of the plate beneath the raised cone. Lower the cone to rest on the sample and place a load of approximately 1000 g on top of the shaft to ensure contact between the cone and plate. 10.2 Place the cone-plate viscometer on a hot plate and allow it to remain there until an ohmmeter, or other electrical device, indicates contact between the cone and plate. Remove the viscometer from the hot plate, allow it to cool until the cone and plate are cool enough to touch. Remove with a non-scratching blade any asphalt on the edge of the cone and on the plate around the cone. 10.3 Place the viscometer in position in the constanttemperature bath. Allow at least 30 min for it to attain the bath temperature. Level the viscometer.
11. Calculation 11.1 Select the calibration factors corresponding to the cone and cord used. For each load and angular velocity, calculate the shear stress, S, in dynes per square centimetre, the shear rate, D, the reciprocal seconds, and the viscosity, n, in poises as follows: S = Ks(L - F) O = KD(O/t) J, = S / D
(4) (5) (6)
12. Report 12.1 Report whether alternative procedure No. 1 or No. 2 was used. 12.2 Report test temperature, viscosity, shear rate and, if fracture occurs, the shear stress resulting in fracture. 13. Precision and Bias 7 13.1 The following precision statement is based on AC 5, AC 10, AC 20, and AC 40 test samples at 25°C at shear rates of 5 x l0 -s, 5 × l0 -2, and 5 × l0 -~ reciprocal seconds. 13.2 The single-operator coefficient of variation has been found to be 3.8 %.8 Therefore, results of two properly conducted tests by the same operator on the same sample using the same viscometer should not differ from each other by more than l 1%8 of their average. 13.3 The multilaboratory coefficient of variation has been found to be 8.4 %.8 Therefore, results of two different laboratories on identical samples of a material should not differ from each other by more than 24 %s of their average. 13.4 No bias can be assigned to this determination. 7 Supporting data are available from ASTM Headquarters. Request RR: D04- 100 I 8 These numbers represent, respectwely, the (IS %) and (D2S %) limits as described m Practice C 670
496
~) D 3205 The American Soctety for Testing and Materials takes no pos~hon respechng the vahdtty of any patent rights asserted Jn connecbon with any Item menboned in th~s standard Users of this standard are expressly advised that determlnatton of the vahdlty of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility This standard Js Sublect to rewslon at any time by the responsible technical committee and must be revtewed every hve years and ff not revised, either reapproved or withdrawn. Your comments are mvtted either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters Your comments wdl receive careful consideration at a meeting of the responstble technical commfftee, which you may attend If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr H~rbor Drive, West Conshohocken, PA 19428
497
(~
II1~ INNTII llI I 1~ i.t'rluH rum
DesignatiOn:D 3227 - 960
Art American National Standard
Designation: 342/93
Standard Test Method for Mercaptan Sulfur in Gasoline, Kerosine, Aviation Turbine, and Distillate Fuels (Potentiometric Method) 1 This standard is issued under the fixed designation D 3227; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year &last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense. Consult the DoD Index of Spec~cations and Standards for the spec~c year of issue which has been adopted by the Department of Defense. This test method has been approved by the sponsoring committee and accepted by the cooperation societies in accordance with established procedures. ~l NffrE--Figure 2 was corrected editorially in April 1997.
1. Scope 1.1 This test method covers the determination of mercaptan sulfur in gasolines, kerosines, aviation turbine fuels, and distillate fuels containing from 0.0003 to 0.01 mass % of mercaptan sulfur (Note 4). Organic sulfur compounds such as sulfides, disulfides, and thiophene do not interfere. Elemental sulfur in amounts less than 0.0005 mass % does not interfere. Hydrogen sulfide will interfere, if not removed as described in 9.2. 1.2 The values in acceptable SI units are to be regarded as the standard. The values in parentheses are for information only. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Notes 1, 2, 3, 5, and 6.
D 4177 Practice for Automatic Sampling of Petroleum and Petroleum Products 4
3. Summary of Test Method 3.1 The hydrogen sulfide-free sample is dissolved in an alcoholic sodium acetate titration solvent and titrated potentiometricaUy with silver nitrate solution, using as an indicator the potential between a glass reference electrode and a silver/silver-sulfide indicating electrode. Under these conditions, the mercaptan sulfur is precipitated as silver mercaptide and the end point of the titration is shown by a large change in cell potential. 4. Significance and Use 4.1 Mercaptan sulfur has an objectionable odor, an adverse effect on fuel system elastomers, and is corrosive to fuel system components. 5. Apparatus 5.1 As described in 5.2 through 5.5; alternatively, any automatic titration system may be used that, using the same electrode pair described in 5.3, is capable of performing the titration as described in Section 9 and selecting the endpoint specified in I0.1 with a predsion that meets or is better than that given in Section 12. 5.2 Meter--An electronic voltmeter, operating on an input of less than 9 x 10-12 A and having a sensitivity of+_2 mV over a range of at least :t:l V. The meter shall be electrostatically shielded, and the shield shall be connected to ground? 5.3 Cell System, consisting of a reference and indicating electrode. The reference electrode should be a sturdy, penciltype glass electrode, having a shielded lead connected to ground. The indicating electrode shall be made from a silver wire, 2 mm (0.08 in.) in diameter or larger, mounted in an insulated support. Silver billet electrodes can also be used.
2. Referenced Documents 2.1 A S T M Standards: D 1193 Specification for Reagent Water 2 D 1250 Guide for Petroleum Measurement Tables 3 D 1298 Test Method for Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method 3 D 4052 Test Method for Density and Relative Density of Liquids by Digital Density Meter 4 D4057 Practice for Manual Sampling of Petroleum and Petroleum Products 4 t This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee 1:)02.03 on Elemental Analysis. Current edition approved Dec. 10, 1996. Published February 1997. Originally published as D 3227 - 73. Last previous edition D 3227 - 92. 2 Annual Book of ASTM Standards, Vol I 1.01. 3 Annual Book of ASTM Standards. Vol 05.01. 4 Annual Book of ASTM Standards, Vo105.02.
s Any apparatus that will give equal or better precision will be acceptable.
498
(~ D 3227 6.7 Silver Nitrate, Standard Alcoholic Solution (0.010 mol/L)--Prepare daily by dilution of the 0.1 N standard. Pipet 100 mL of the 0.1 mol/L standard into a I-L volumetric flask and dilute to volume with 2-propanol. Calculate the exact molarity. 6.8 Sodium Sulfide Solution (10 g/L)--Dissolve 10 g of Na2S in water and dilute to 1 L with water. Prepare fresh as needed. 6.9 Titration Solvent--Low molecular weight mercaptans, as usually found in gasoline, are readily lost from the titration solution if an acidic titration solvent is used. For the determination of the higher molecular weight mercaptan as normally encountered in kerosines, aviation turbine fuels and distillate fuels, the acidic titration solvent is used to achieve more rapid equilibrium between successive additions of the titrant. 6.9.1 Alkaline Titration Solvent--Dissolve 2.7 g of sodium acetate trihydrate (NaC2H302.3H20) or 1.6 g of anhydrous sodium acetate (NaC2H302) in 25 mL of oxygenfree water and pour into 975 mL of 2-propanol (99 %) (Note 4). Remove dissolved oxygen by purging the solution with a rapid stream of nitrogen for 10 rain each day prior to use; keep protected from the atmosphere. 6.9.2 Acidic Titration Solvent--Dissolve 2.7 g of NaC2H302"3H20 or 1.6 g of NaC2HaO2 in 20 mL of oxygen-free water and pour into 975 mL of 2-propanol (99 %) (Note 4) and add 4.6 mL of glacial acetic acid. Remove dissolved oxygen by purging the solution with a rapid stream of nitrogen for 10 min each day prior to use; keep protected from the atmosphere. 6.10 Polishing Paper or Cloth, 18 ttm average particle size (800 grit) abrasive.
5.4 Buret, 10-mL capacity, graduated in 0.05-mL intervals, with a tip that extends approximately 120 mm (5 in.) below the stopcock. 5.5 Titration Stand, preferably built as an integral part of the meter housing and provided with supports for the electrodes and electrical stirrer, all connected to ground. No permanent change in meter reading should be noticeable upon connecting or disconnecting the stirring motor.
6. Reagents and Materials 6.1 Purity of Reagents--Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available. 6 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 6.2 Water--Reagent grade, Type I, Specification D 1193. 6.3 Cadmium Sulfate. Acid Solution (150 g/L)--Dissolve 150 g of cadmium sulfate (3CDSO4.8H20) in water. (Warning--See Note 1) Add 10 mL ofH2SO4 (Warning--See Note 2) (1+5) and dilute to 1 L with water. NOTE 1: Warning--Poison. May be fatal if swallowed or inhaled. A known carcinogen (animal positive). N o t e 2: Warning--Poison. Causes severe bums. Harmful or fatal if swallowed or inhaled.
6.4 Potassium Iodide, Standard Solution (approximately 0.1 mol/L)--Dissolve 17 g of KI (weigh to 0.01 g) in 100 mL of water in a 1-L volumetric flask and dilute to 1 L. Calculate the exact molarity. 6.5 2-Propanol--(Warning--See Note 3).
7. Sampling
NOTE 3: Warning--Flammable.
7.1 Take the sample in accordance with Practice D 4057 or Practice D 4177.
6.6 Silver Nitrate, Standard Alcoholic Solution (0.1 mol/ L)--Dissolve 17 g of AgNO 3 in 100 mL of water in a I-L volumetric flask and dilute to 1 L with 2-propanol (99 %) (Note 4). Store in a dark bottle and standardize at intervals frequent enough to detect a change of 0.0005 or greater in molarity. NOTE 4--It is important to pass the 2-propanol through a column of activated alumina to remove peroxides that may have formed on storage; failure to remove peroxides will lead to low results. It is not necessary to perform this step if the alcohol is tested and found free of peroxides.
8. Preparation of Apparatus 8.1 Glass Electrode--After each manual titration, or batch of titrations, in the case of automatic titration systems, wipe the electrode with a soft, clean tissue and rinse with water. Clean the electrode at frequent intervals (at least once a week) by stirring in cold chromic acid solution (Warning-See Note 6) for a few seconds (10 s max). When not in use, keep lower half of the electrode immersed in water. NOTE 6: Warnlng--Causes severe bums. A recognized carcinogen.
6.6.1 StandardizationmAdd 6 drops of concentrated HNO3 (Tel dens 1.42) (Warning--See Note 5) to 100 mL of water in a 300-mL tall-form beaker. Remove oxides of nitrogen by boiling for 5 min. Cool to ambient temperature. Pipet 5 mL of 0.I mol/L KI solution into the beaker and titrate with the AgNO3 solution choosing the end point at the inflection of the titration curve. NOTE 5: Warning--Poison. Causes severebums. Harmful or fatal if swallowedor inhaled.
Strong oxidizer--contact with other material may cause fire. Hygroscopic. An equivalent, chromium-free cleaning solution may be used. 8.2 Silver/Silver-Sulfide Electrode--Each day prior to use, prepare a fresh silver sulfide coating on the electrode by the following method: 8.2.1 Burnish electrode with polishing paper or cloth until a clean, polished silver surface shows. 8.2.2 Place electrode in operating position and immerse it in 100 mL of titration solvent containing 8 mL of Na2S solution. 8.2.3 Add slowly from a buret, with stirring, 10 mL of 0.1 mol/L AgNO3 solution over a period from 10 to 15 rain. 8.2.4 Remove electrode from solution, wash with water, and wipe with a soft, clean tissue. 8.2.5 Between manual titrations, or batches of titrations
6 Reagent Chemicals, American Chemical Society Spec~cations, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.IC, and the United States Pharmacopeia and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
499
o 3227 in the case of automatic titration systems, store the electrode a minimum of 5 min in 100 mL of titration solvent containing 0.5 mL of the 0.1 mol/L AgNO3 solution.
Elemental Sulfur + -60C --Excess Mercaptans '~
9. Procedure
9.1 Determination of Density--If the sample is to be measured volumetrically, determine the density by Test Methods D 1298 or D 4052 at the temperature at which the test portion will be taken, either directly or from the density determined at a reference temperature and converted to the transfer temperature by use of the Petroleum Measurement Tables (Guide D 1250). 9.2 Removal of Hydrogen Sulfide--Test the sample qualitatively for hydrogen sulfide (H2S) by shaking 5 mL of the sample with 5 mL of the acid CdSO4 solution. If no precipitate appears, proceed with the analysis of the sample as described in 9.3. If a yellow precipitate appears, remove the H2S in the following manner: Place a quantity of the sample, three to four times that required for the analysis, in a separatory funnel containing a volume of the acid CdSO4 solution equal to one half that of the sample and shake vigorously. Draw off and discard the aqueous phase containing the yellow precipitate. Repeat the extraction with another portion of the CdSO4 solution. Again draw off the aqueous phase, and wash the sample with three 25 to 30-mL portions of water, withdrawing the water al~er each washing. Filter the hydrocarbon through a rapid paper. Test a small portion of the washed sample in a test tube with a few millilitres of the CdSO4 solution. If no further precipitate is formed, proceed as directed in 9.3. If a precipitate appears, repeat the extraction with the CdSO4 solution until all of the H2S has been removed. 9.3 Measure with a pipet or weigh 20 to 50 mL of the original or treated sample into a 300-mL beaker containing 100 mL of the appropriate titration solvent. Place the beaker on the titration stand or on the auto-sampler of an automatic titration system. If an automatic titration system is used, set up the system to reproduce the experimental conditions specified in 9.3.1, 9.3.2, and 9.3.3. Adjust the position of the titration stand so that the electrodes are about half immersed. Fill the buret with 0.01 mol/L alcoholic AgNO 3 solution and position it in the titration assembly so that the tip extends approximately 25 mm (1 in.) below the surface of the liquid in the beaker. Adjust the speed of the stirrer to give vigorous stirring without spattering. 9.3.1 Record the initial buret and cell potential readings. The usual meter readings for mercaptan presence are in the -250 mV to -350 mV range. Add suitable small portions of 0.01 mol/L AgNO 3 solution and, after waiting until a constant potential has been established, record the buret and meter readings. Consider the potential constant if it changes less than 6 mV/min. NOTE 7--If potential readings obtained with freshly prepared electrodes are erratic, it is possible that the electrodes are not properly
conditioned. This difficultyusually disappears in succeedingtitrations. NOTE 8--With certain instruments, the algebraic sign of the potentials may appear reversed. 9.3.2 When the potential change is small for each increment of AgNO3 solution, add volumes as large as 0.5 mL. When the change of potential becomes greater than 6 mY/0.1 mL, use 0.05-mL increments of 0.01 mol/L AgNO3 500
Mercaptans + Excess Sulfur
-400 -t ' ~ Silver Sulfide Mercaptans A l o n e ~ - ~ --. l > -200
o
+200
Sl Iver ~ercaptide
Silver Sulfide
m
+400
Millilitres FIG. 1
of Silver Nitrate
Solution
Illustra~ve PotenUometdc Titration Curves
solution. Near the end point of the titration, 5 or 10 min may elapse before a constant potential is obtained. Although it is important to wait for equilibrium conditions, it is also important that the duration of the titration be as short as possible in order to avoid oxidation of the sulfur compounds by atmospheric oxygen. Once started, a titration must never be interrupted and resumed later. 9.3.3 Continue the titration until the meter reading change of the cell potential per 0.1 mL of 0.01 M A g N O 3 solution has become relatively constant. Consider the potential constant if it changes less than 6 mV/min. Remove the titrated solution, rinse the electrodes with alcohol and wipe with a dry tissue. If an automatic titration system is used, rinse the electrodes well with alcohol, allow the excess alcohol to drain off the electrode; then proceed with the next sample. Between successive determinations (or batches of determinations in the case of automatic titration systems) on the same day, store the electrodes in accordance with 8.1 and 8.2.5. 10. Interpretation of Results
10.1 Treatment of Data--Plot the cumulative volumes of 0.01 M AgNO 3 solution added against the corresponding cell potentials. Select the end point at the most positive value of the steepest portion of each "break" in the titration curve as shown in Fig. 1. The shape of the titration curve may change with different instruments. However, the above interpretation of the end point should be followed. 10.1.1 MercaptansOnly--If mercaptans alone are present in the sample, the titration produces a curve of the first type shown in Fig. 1, having an initial plateau at a potential equal to or more negative than -250 mY, and an end point when a potential change of less than 6 mV/min is reached and the change in mV/min of titrant is reduced with each incremental addition. 10.1.2 Mercaptans and Elemental Sulfur--When elemental sulfur and mercaptans are both present in the sample, a chemical interaction occurs which, in the titration
o a22z 0.0008
m a/i
0.0006
/
u e-
11 0.0004 0
/
/
/
< E
/
/
.,..,,.
E 0.0002 X t~
=E
0.0000 0.000
0.002
0.004
0.006
0.008
0.010
Mercaptan Sulfur, Mass % ---FIG. 2
Repeatability
Reproducibility
Precision Curve for Mercaptan Sulfur in Gasolines, Kerosines, Aviation Turbine, and Distillate Fuels
solvent used, precipitates silver sulfide (Ag2S) during the titration. I0.1.3 When mercaptans are present in excess, the end of the Ag2S precipitation occurs at about -550 to -350 mV, and is followed by the precipitation of the silver mercaptide to the +300-mV end point. This situation is shown in the middle curve of Fig. 1. Since all of the Ag2S originates from an equivalent amount of mercaptan, the total titration to the mercaptide end point must be used to calculate the amount of mercaptan sulfur. 10.1.4 When elemental sulfur is present in excess, the end of the Ag2S precipitation is taken in the same region (+300 mV) as in the case of silver mercaptide, and is calculated as mercaptan sulfur.
12. Precision and Bias 12.1 Precision: 12. I. 1 The precision of this test method as determined by statistical examination ofinterlaboratory results is as follows: 12.1.1.1 Repeatabifity--The difference between two successive test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test material, would in the long run, in the normal and correct operation of the test method, exceed the following values only in one case in twenty: Repeatability 0.00007+ 0.027x (Note 9) where: x = average mercaptan sulfur, mass %. NOTe 9--This amount is shown graphicallyin Fig. 2. 12.1.1.2 Reproducibility--The difference between two single and independent results obtained by different opera. tors working in different laboratories on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following values only in one case in twenty: Reproducibility 0.00031+ 0.042x (Note 9) where: x = average mercaptan sulfur, mass %. 12.2 B i a s - - T h e bias for the procedure in this test method has not been determined.
11. Calculation 11.1 Calculate the mercaptan sulfur content of the sample as follows: Mercaptan sulfur, mass % -- (AM x 3.206)/W or
Mercaptan sulfur, mass % ffi (AM × 3.206)/(d × It) where: A = miUilitres of AgNO 3 solution required to reach the end point in the vicinity of +300 mV (Fig. 1), d = density of sample at transfer temperature, g/mL, M = molarity of the AgNO 3 solution, W = grams of sample used, 3.206 = 100 x g meq weight S in mercaptan, and V = mL of sample used.
13. Keywords 13. l mercaptan; potentiometric; sulfur
501
o 3227 The American Society for Testing and Materials takes no position respecting the validity of any patent rights esaerted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and # not revised, either reepproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible teshn/cal committee, which you may attend, ff you feel that your comments have not received a fair beefing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohonkan, PA 19428.
502
(~
Designation:D 3230 - 89
An Amen.an National StandaKl
Standard Test Method for Salts in Crude Oil (Electrornetric Method) 1 This standard is issued under the fixed designation D 3230; the number immediately following the designation indicates the year of original adoption or, in the case &revision, the year of last revision. A number in parentheses indicates the year of last re.approval. A superscript epsilon (E) indicates an editorial change since the last revision or re.approval.
1. Scope 1.1 This test method covers the determination of salts in crude oil. 1.2 The accepted concentration units are pounds NaCI per 1000 bbl of crude oil.
1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary, statements, see 6.3, 6.4, and 6.11. 2. Referenced Documents
2.1 ASTM Standards." D91 Test Method for Precipitation Number of Lubricating Oils 2 D381 Test Method for Existent Gum in Fuels by Jet Evaporation 2 D 843 Specification for Nitration Grade Xylene 3 D 1193 Specification for Reagent Water 5 D4057 Practice for Manual Sampling of Petroleum and Petroleum Products 4 D 4177 Method for Automatic Sampling of Petroleum and Petroleum Products 4 3. Summary of Test Method 3.1 This test method is based on the conductivity of a solution of crude oil in a polar solvent when subjected to an alternating electrical stress (Note 1). The sample is dissolved in a mixed solvent and placed in a test cell consisting of a beaker and two parallel stainless steel plates. An alternating voltage is impressed on the plates and the resulting current flow is shown on a milliammeter. The salt content is obtained by reference to a calibration curve of current versus salt content of known mixtures.
4. Significance and Use 4.1 This test method is used to determine the salt content of crude oils, a knowledge of which is important in deciding whether or not the crude needs desalting. Excessive salt left in the crude frequently results in higher corrosion rates in refining units. 5. Apparatus 5.1 Assemble the appa~tus as described in Annex A 1. 6. Reagents and Materials
6.1 Purity of Reagents--Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available, e Other grades may be used, provided it is fwst ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 6.2 Purity of Water--Unless otherwise indicated, references to water shall be understood to mean reagent water as defined by Type II of Specification D 1193. 6.3 Alcohol Solvent Mixdd Solution, (Warning--See Note 2) Mix 63 volumes of l-butanol and 37 volumes of absolute methanol; to each litre of this mixture, add 3 m L of water. NoTE 2: Warning--Flammable. Liquid causes eye burns. Vapor harmful. May be fatal or cause blindness if swallowed or inhaled. Cannot be made non-poisonous. NoTE 3--The mixed alcohol solvent is suitable for use if its conductivity is less than 0.25 mA when indicated electrode voltage is 125 V a-c. Readings greater than 0.25 mA at 125 V a-c may be due to excessive water in the solvent and indicate that methanol is not anhydrous. 6.4 ASTM Precipitation Naphtha, (Warning--See Note 4), conforming to the requirements of Test Method D 91. NoTE 4: Warning--Extremely Flammable. Harmful if inhaled. Vapors may cause flash fire. 6.5 Calcium Chloride Solution (10 g/L)---Transfer 1.000 g of calcium chloride (CaCI2), or the equivalent weight of a hydrated salt, into a 100-mL volumetric flask and dissolve in 25 mL of water. Dilute to the mark with mixed alcohol solvent. 6.6 Magnesium Chloride Solution (10 g/L)--Transfer 1.000 g of magnesium chloride (MgC12, or the equivalent weight of a hydrated salt), into a 100-mL volumetric flask
Nor~ l--This test method will measure conductivity due to the salts in the crude oil. Calibration curves are based on standards prepared to approximate the type and concentration of salts in the crude oils being tested. l This test method is under the jurisdiction of ASTM Committee 13-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee 1302.03 on Elemental Analysis. Current edition approved Oct. 27, 1989. Published December 1989. Originally published as D 3230 - 73. Last previous edition D 3230 - 83. 2 Annual Book of ASTM Standards, Vol 05.01. 3 Annual Book of ASTM Standards, Vol 06.03. 4 Annual Book of ASTM Standards, Vol 05.03. s Annum Book of ASTM Standards, Vols 06.03 and 11.01.
6 "Reagent Chemicals. American Chemical Society Specification," Am. Chem. Soc., Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see ~Reagent Chemicals and Standards," by Joseph Rosin, D. Van Nostrand Co., New York, NY and the "United States Pharmacopeia. ~
503
~l~ D 3230 and dissolve in 25 mL of water. Dilute to the mark with mixed alcohol solvent. 6.7 Oil, Refined Neutral--Any refined salt-free oil of approximately 100 SUS viscosity at 38"C (100*F) and free of additive. 6.8 Salts, Mixed Solution (Concentrated Solution)--Com. bine 10.0 mL of the CaC12 solution, 20.0 mL of the MgCI 2 solution, and 70.0 mL of the NaCI solution and mix thoroughly. NOTE 5--The 10:20:70 proportions are representative of the salts present in a wide range of crude oils. When the relative proportions of calcium, magnesium and sodium chlorides are known for a given crude oil, such proportions should be used for most accurate results. 6.9 Salts, Mixed Solution (Dilute Solution)mTransfer 10.0 mL of the concentrated mixed salts solution into a 1000-mL volumetric flask and dilute to the mark with mixed alcohol solvent. 6.10 Sodium Chloride Solution (10 g/L)mTransfer 1.000 g of sodium chloride (NaCI) into a 100-mL volumetric flask and dissolve in 25 mL of water. Dilute to the mark with mixed alcohol solvent. 6.11 Xylene (Warning~See Note 6) nitration grade, conforming to the requirements of Specification D 843. NOTE 6: Warning--Flammable. Vapor harmful.
7. Sampling 7.1 Take the sample in accordance with Practice D 4057, or by Method D 4177.
voltages are applied for high standards. Do not disturb the standardization of the instrument when using other applied voltages. The conductivity of solutions is affected by the temperature at which measurements are made. The temperature of samples at the time of current measurement must be within 3"C (5°F) of the temperature at which the calibration curves were m a d e .
9.2 Run a blank by following the procedure in 9.3 and 9.4 omitting the mixed salts solution. If the indicated electrode current is greater than 0.25 mA at 125 V a-c, water or another conductive impurity is present and its source must be found and eliminated before calibration can be completed. Determine a blank each time fresh xylene or mixed solvent is used. 9.3 Into a dry 100-mL graduated, glass-stoppered mixing cylinder, add 15 m L of xylene. From a to contain pipet add 10 m L of neutral oil. Wash the pipet with xylene until free of oil. Make up to 50 mL with xylene. Stopper and shake the cylinder vigorously for at least 60 s to effect solution. Add a quantity of dilute mixed salts solution in accordance with Table 1 appropriate to the range of salt contents to be measured. Dilute to 100 mL with mixed alcohol solvent. Again shake the cylinder vigorously for 30 s to effect solution and allow the solution to stand 5 rain. Pour the solution into a dry electrode beaker. TABLE 1
8. Standardization of the Electrometric Salt Determinator Instrument
8.1 Connect the electrometric salt determinator instrument (AI.I) to a II0-V, 50 or 60-Hz source. Set toggle switch $2 so that the 25 000 fl (+0.5 %) noninductive precision resistor is in the circuit. Set toggle switch SI to the high scale (H) and turn switch $3 to the ON position. Adjust the voltage to 125 V a-c. Press switch $4 and adjust the 25-fl potentiometer so that the milliammeter is deflected to 0.1 mA. Release switch $4. Change toggle switch S I to the low scale (L). Press switch $4 and adjust the 50-fl potentiometer so that the pointer is deflected to full scale (1.0 mA). Release switch $4. Turn switch $3 to the OFF position. Turn switch $2 to the electrode position. NOTE 7--The low scale (L) is intended for use with samples of low salt content and is thus more sensitivethan the high scale (H). The full scale reading of the milliammeter when toggle switch SI is in the L position is 1.0 mA; full scale meter indication when switch SI is in the H position is 10 mA. 9. Calibration
9.1 The apparatus and procedure are calibrated against solutions of neutral oil and mixed salts solution in xylene because of the extreme difficulties in keeping crude oil-brine mixtures homogeneous. The calibration may be confirmed, if desired, by careful replicate analysis of crude-oil samples by exhaustive extraction of salts with hot water followed by titration of the halides in the extract. In calibrating over a wide range of salt contents, it is necessary to apply voltages other than the standardizing voltage (125 V a-c) to obtain current readings within the limit of the instrument (0 to 10 mA). Higher voltages are applied for low standards and lower
Standard Samples
Salt as NaCI Pounds per 1000 bb~of Crude Oil
Mixed Salts Solution (dilute), mL
1.0 3.0 5.0 10.0 15.0 20.0 25.0 30.0 40.0 50.0 65.0 75.0 85.0 I00.0 150.0
0.3 0.9 1.5 3.0 4.5 6,0 7.5 9.0 12.0 15.0 19.5 22.5 25.5 30.0 45.0
9.4 Immediately place the electrodes in the beaker making sure that the upper edge of the electrode is at least 1/16in. ( 1.6 ram) below the surface of the liquid. Set toggle switch S I to high (H) position. Connect the electrodes to the instrument. Turn switch $3 to ON position. Adjust the indicated electrode voltage to a series of values, for example 25, 50, 125, 200 and 250 V a-c. At each voltage, press $4 and note the miUiammeter reading and record to the nearest 0.01 mA. If the reading becomes less than 0.1 mA, change toggle switch S I to low (L) position. Record the voltage and the corresponding milliammeter reading and continue reading again, recording to the nearest 0.01 mA. Release switch $4. Turn switch $3 to OFF position. Remove electrodes from solution, rinse with xylene followed by naphtha and allow them to dry. NOTE 8: Precaution--ln addition to other precautions, always keep the switch $3 in the OFF position except when the electrodesare in the
504
I1~ D 3230 electrode beaker or when switch $2 is in the calibrate position. The voltage applied to the electrodes may be as great as 250 V a-c, thus hazardous. Accidental short-circuiting of the electrodes may destroy some components of the apparatus.
9.5 Repeat as in 9.3 and 9.4 using other volumes of mixed salts solution (dilute) as needed to cover the range of salt contents of interest. 9.6 Subtract the current reading of the blank from the indicated current readings of the standard samples and plot the salt content (ordinate) against net milliampere reading (abscissa) for each voltage on 3 by 3 cycle log-log paper.
10. Procedure 10.1 To a dry 100-mL graduated, glass-stoppered cylinder add 15 mL of xylene and, by means of a to contain pipet, 10 rnL of crude oil sample. Wash the pipet with xylene until free of oil. Make up to 50 mL with xylene. Stopper and shake the cylinder vigorously for at least 1 rain (Note 9). Dilute to 100 mL with mixed alcohol solvent and again shake vigorously for 30 s. After allowing the solution to stand for 5 rain, pour it into the dry electrode beaker. Follow the procedure in 9.4 to obtain a current reading at the appropriate voltage. Record the indicated electrode current to the nearest 0.01 mA at the voltage. If necessary, record the temperature of the solution (9.1). NOTE 9--Salt brine may be adsorbed on the walls of glass pipets used to measure the sample. If examination of the pipet indicates this
condition, insert the pipet tip beneath the surface of the xylene in the
graduate and allow to drain. Wash the pipet free of the salt brine with mixed alcohol solvent. Raise the pipet from the xyleneand rinse the tip with mixed alcohol solvent. 10.2 Determine the current reading of the blank at the same voltage. 10.3 Subtract the current reading cf the blank at the indicated voltage from the current reading of the sample to obtain the net current reading. From the calibration graph (9.6) read the indicated salt content corresponding to the net milliampere reading of the sample.
11. Precision and Bias 11.1 This test method has been extensively tested in a number of laboratories and found to give results comparable to those from other procedures for determining salt in crude oils. Exact precision data have not been derived because of inability to obtain stable, homogeneous, and representative samples for cooperative testing. 11.2 The responsible ASTM D2.03 study group is currently re-evaluating this test method to determine precision values and to extend the scope of the test method to allow use of modern commercial conductance apparatus. l !.3 The bias for determining the salt content of crude oils by this test method cannot be determined since a suitable standard reference material is not available.
ANNEX
(Mandatory Information) AI. APPARATUS AI.I.6 Potentiometer, 25 t, ten turns. ~ A1.1.7 Potentiometer. 50 t , ten turns. 12
AI.1 Electrometric Salt Determinator (ESD) Components (Fig. AI.I, Note AI.I)
Nor~ A I . I - - A n equivalent part may be substituted in each case provided the electrical characteristics of the entire circuit remain unchanged and that inductive effects and stray currents are avoided.
AI.I.I Milliammeter, 0-1 rnA d-c with 0-1 mA a-c scale, 88 fl internal resistance. 7 AI.I.2 Bridge Rectifier, full-wave, 0.75 A capacity at 60 Hz, ambient temperature; minimum of 400 PRV (Peak Reverse Voltage)) AI.I.3 AC Voltmeter, rectifier type, 2000 t/v, 0 to 300-range. 9 AI.I.4 Variable Voltage Autotransformer, input 105-117 V 50/60 Hz, output 0-132 V, 1.75 A capacity. AI.1.5 Transformer, plate supply 240 V, center tap 50/60 Hz, 250 mA d-c capacity (filament voltage 5 V, 3.0 A not
A1.2 Test Cell Components (Fig. AI.2) AI.2.1 Berzelius Beaker, 100-mL tall form without lip, as described for use in Test Method D 381. A1.2.2 Electrode Assembly, as shown in Figs. AI.2 and AI.3. The electrodes mounted in parallel position, exactly opposed and 0.25 in. (6.4 ram) apart, and electrically separated by a nylon or TFE-fluorocarbon spacer. Care must be exercised in handling the elec~ode assembly to prevent bending or misalignment of the electrodes.
used). '° Weston Model 301, available from Weston Instruments, Inc., 614 Frelinghuysen Ave., Newark, N. J. 07114, has been found satisfactory for this purpose. s Mallory Type FW-400 available from Mallory Industries, Inc., 75 Custer St., West Hartford, Conn. 06090, has been found satisfactory for this p u ~ . 9Weston Model 304, available from Weston Instruments, Inc., 614 Frelinghuysen Ave., Newark, N. J. 07114. t°Stancor P6146, available from Stancor/Electronie, Marketing Division of Essex Wire Corporation, 3501 West Addison St., Chicago, IlL 60618.
i i 25-ohm, 10-turn potentiomcter, linear, 5 watt such as Amphenol Model No. 2200 available from Amphenol, Controls Div., 120 S. Main St., Janesviile, Wis.
53545. 1250-ohm, 10-turn potentiometer, linear, 5 watt such as Amphenol Model No. 2200 available from Amphenol, Controls Div., 120 S. Main St., Janesville, Wis. 53545.
505
@ D 3230 I PIT Switch (PRESS TO MAKE) J
Autoformer S2 ~
~T"~25KJ%
2P2TX~r Pilot L i g h t , - ~ 5A Fuse
S~,
2PI' 3wih 50 "L"
115 VAC 60 Hertz
SI
I IP2T ~>Switch
r
~. ;~ 25 J~. i" "H"
To Electrodes
I0 Turn. 5 Wott Potentlometers FIG. A1.1 250 or 540 Volt Transformer
J ps,,
L,,,.. o,A.o,,.. T.,O. o'.o,,
MAT[RIAL - NYLON OR BETTER
*/z" OIA, • 3/is" O[[P.
--BANANA TIPJACK---~
~
-
~
SPACSR:%" "O.e.T/,e"0.0. .ATeR~L; CA.VASBASS
J //
j,y--'ELEGTRODE SPACER & SCREWS
/ /
~~.250
~-~
BAKeLITe
: ,/s,,~--41114"
MATERIAL ; NON CONDUCTOR SUCH AS NYLON OR SIMI'AR
2
'~ ~_ i/4.
~ SOLOER
II
MATERIAL- 16CA. STAINLEeSSTEEL FIG. A1.3 Electrode Assembly
+ .001
FIG. A1.2 Test Cell 506
APPROX.
~) D 3230 The American Society for Testing and Material8 takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement Of such rights, are entirely their own respot~lbllity. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either respproved or withdrawn. Your comments are invited either for revlalon of thl$ standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful ¢ o r * ~ l o n at a meeting of the respormlble technical committee, whlGh you may attend, ff you feel that your comments have not received 8 fair hearing you shoul¢l make your view= known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
507
Designation: D 3235 - 93
An American National Standard
Standard Test Method for Solvent E x t r a c t a b l e s in Petroleum W a x e s 1 This standard is issued under the fixed designation D 3235; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last re.approval. A superscript epsilon (0 indicates an editorial change since the last revision or reapproval.
volume % methyl ethyl ketone and 50 volume % toluene. The solution is cooled to -32°C (-25°F) to precipitate the wax, then filtered. The solvent extractables content is determined by evaporating the solvent from the filtrate and weighing the residue.
1. Scope 1.1 This test method covers the determination of solvent extractables in petroleum waxes. 1.2 The values stated in acceptable metric units are to be regarded as the standard. The values in parentheses are for information only. 1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appro. priate safety and health practices and determine the applicability of regulatory limitations prior to use.
5. Apparatus 5.1 Filter Stick and Assembly, consisting of a 10-mm diameter sintered glass filter stick of 10 to 15 ~m maximum pore diameter as determined by the method in the Appendix, provided with an air pressure inlet tube and delivery nozzle. It is provided with a ground-glass joint to fit a 25 by 170-ram test tube. The dimensions for a suitable filtration assembly are shown in Fig. 1.
2. Referenced Documents
2.1 A S T M Standards." D 740 Specification for Methyl Ethyl Ketone 2 D 841 Specification for Nitration Grade Toluene 2 D 1078 Test Method for Distillation Range of Volatile Organic Liquids 2 D 1218 Test Method for Refractive Index and Refractive Dispersion of Hydrocarbon Liquids 3 D 1364 Test Method for Water in Volatile Solvents (Fischer Reagent Titration Method) 2 D 1613 Test Method for Acidity in Volatile Solvents and Chemical Intermediates Used in Paint, Varnish, Lacquer and Related Products 2 E I Specification for ASTM Thermometers 4 E 128 Test Method for Maximum Pore Diameter and Permeability of Rigid Porous Filters for Laboratory Use 5 2.2 IP Standard." Colour, Lovibond, IP 17, Method B
NOTE I - - A metallic filter stick may be employed if desired. A fdter stick ) made o f stainless steel and having a 12.7-ram (0.50-in.) disk o f 10 to 15 n m m a x i m u m pore diameter, as determined by Test Method E 128, has been found to be satisfactory. The metallic apparatus is inserted into a 25 by 150-ram test tube and held in place by means o f a cork.
5.2 Cooling Bath, consisting of an insulated box with 25.4-mm (l.00-in.) holes in the center to accommodate any desired number of test tubes. The bath may be filled with a suitable medium such as kerosine, and may be cooled by circulating a refrigerant through coils, or by using solid carbon dioxide. A suitable cooling bath to accommodate three test tubes is shown in Fig. 2. 5.3 Dropper Pipet, provided with a rubber bulb, and calibrated to deliver 0.5 + 0.05 g of molten wax. 5.4 Transfer Pipet, calibrated to deliver 15 + 0.06 mL. 5.5 Air Pressure Regulator, designed to supply air to the filtration assembly (8.5) at sufficient pressure to give an even flow of filtrate. Either a conventional pressure-reducing valve or a mercury bubbler-type regulator has been found satisfactory. The latter type, illustrated in Fig. 3, consists of a 250-mL glass cylinder and a T-tube held in the cylinder by means of a rubber stopper grooved at the sides to permit the escape of excess air. The volume and pressure of the air supplied to the filtration assembly is regulated by the depth to which the T-tube is immersed in mercury at the bottom of the cylinder. Absorbent cotton placed in the space above the mercury prevents the loss of mercury by spattering. The air
3. Significance and Use 3. I The solvent extractables in a wax may have significant effects on several of its properties such as strength, hardness, flexibility, scuff resistance, coefficient of friction, coefficient of expansion, melting point, and staining characteristics. Whether these effects are desirable or undesirable depends on the intended use of the wax. 4. Summary of Test Method 4.1 The sample is dissolved in a mixture consisting of 50 i This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.10 on Properties of Petroleum Wax. Current edition approved Sept. 15, 1993. Published November 1993. Originally published as D 3235 - 73. Last previous edition D 3235 - 88. 2 Annual Book of ASTM Standards, Vol 06.03. 3 Annual Book of ASTM Standards, Vol 05.01. 4 Annual Book of ASTM Standards, Vol 05.03. 5 Annual Book of ASTM Standards, Vol 14.02.
6 Available from the Institute of Petroleum, 61 New Cavendish St., London, W.I, England. 7 A suitable metal filter stick with designated porosity G may be obtained from the Pall Trinity Micro Corp., Route 281, Cortland, NY 13045. A list of United Kingdom suppliers can be obtained from the Institute of Petroleum, 61 New Cavendish St., London, W. I, England.
508
o 323s 35-45
65-75
19-21/D
-
-
~:5~73"5--ID-
IN DIRECTIONOFARROW • 25 ODCOOLINGTUBE
.~
__t~J
SINTEREDGLASSDISK
-~-~ 9-11 DIA. All dimensions are in mlUimetres
FIG. 1 Filter Stick
pressure regulator is connected to the filter stick and assembly by means of rubber tubing. 5.6 Thermometers, two, having a range as shown below and conforming to the requirements as prescribed in Specification E 1 or in the specifications for IP Standard Thermometers. One thermometer is required for the cold bath and a second thermometer is required for the sample solution. Thermometer Number
Range
ASTM 7IF IP 72C IP 72F
-35 to +70"F -32 to +21"C -35 to +70"F
and capable of maintaining a temperature of 35 ± I°C (95 ± 2"F) around the evaporation flasks. Construct the jets with an inside diameter of 4 ± 0.2 mm for delivering a stream of clean, dry air vertically downward into the weighing bottle. Support each jet so that the tip is 15 + 5 mm above the surface of the liquid at the start of the evaporation. Supply air at the rate of 2 to 3 L/rain per jet, purified by passage through a tube of 1-cm bore packed loosely to a height of 20 cm with absorbent cotton. Periodically check the cleanliness of the air by evaporating 4 mL of the solvent mixture described in 6.3 by the procedure specified in 8.5. When the residue does not exceed 0.1 rag, the evaporation equipment is operating satisfactorily.
5.7 Weighing Bottles, conical in shape and glass-stop pered, having a capacity of 15 mL. 5.8 Evaporation Assembly, consisting of an evaporating cabinet and connections, essentially as illustrated in Fig. 4,
NOTE 2--Investigations by the European World Federation have indicated that improved precision may be achieved by individually calibrating each nozzle to deliver a flow rate of 2 to 3 L/rain. 5.9 Analytical Balance, capable of reproducing weights to 0.1 rag. The sensitivity should be adjusted so that 0.1 mg will deflect the pointer one half division on the pointer scale. 5. I O Wire StirreruA piece of stiff iron or Nichrome wire of about 0.9 mm in diameter (No. 20 B&S or 20 swg), 250 mm long. A 10-mm diameter loop is formed at each end, and the loop at the bottom end is bent so that the plane of the loop is perpendicular to the wire.
TABLE 1 Specifications for Methyl Ethyl Ketone Property
Specificgravity,20/20°C Color Distillationrange: Below78°C Above81°C Acidity Water content Residue on evaporation
Refractive index at 20°C
(8S'F)
Value 0.805 to 0.807 water white, 1.0 max nil nil 0.003 weight%, max (expressed as acetic acid) 0.3 weight Yo, max residue remaining after evaporation of 4 ml by procedure in 8.5 shall not exceed 0.1 mg 1.378 + 0.002
Method IP 17 (B) ASTM D 1078 ASTM D 1613
6. Solvent
ASTM D 1364
6.1 Methyl Ethyl Ketone, conforming to Specification D 740, or to Table 1. 6.2 Toluene, conforming to Specification D 841. 6.3 Solvent MixtureuPrepare a mixture of 50 volume % methyl ethyl ketone and 50 volume % toluene.
ASTM D 1218
509
~I~ D 3235
THERMOMETER
AIR PRESSURE
ASTIC
dNER Lcr)
CAPACITY FILLED WITH COOLING
MEDIUM
203
"~
(8'¢0
All dimensions e r e In milllmetres (inches) FIG. 2
Cooling Bath
6.4 Store the solvent mixture over anhydrous calcium sulfate (5 weight % of the solvent). Filter prior to use.
nearest 1 mg (Note 3). Swirl the test tube so as to coat the bottom evenly with wax. This permits more rapid solution later. Allow the test tube to cool, and weigh to the nearest 1 rag.
7. Sample 7.1 Obtain a representative portion by melting the entire sample and stirring thoroughly. This is necessary because the extractables may not be distributed uniformly throughout the solidified sample.
NOTE 3~The weight of a test tube which is cleaned by means of solvent will not vary to a significantextent. Therefore,a tare weightmay be obtained and used repeatedly. 8.2 Pipet 15 ml of the solvent mixture into the test tube and place the latter just up to the level of its contents in a hot water or steam bath. Heat the solvent-wax mixture, stirring up and down with the wire stirrer, until a homogeneous solution is obtain. Exercise care to avoid loss of solvent by prolonged boiling.
8. Procedure 8.1 Melt the representative sample in a beaker, using a water bath or oven maintained at 70 to 100"C (160 to 210°F). As soon as the wax is completely melted, thoroughly mix by stirring. Preheat the dropper pipet in order to prevent the solidification of wax in the tip, and withdraw a 0.5-g portion of the sample as soon as possible after the wax has melted. Hold the pipet in a vertical position, and carefully transfer its contents into a clean, dry test tube previously weighed to the
NOTE 4--Very high-meltingwax samples may not form clear solutions. Stir until the undissolvedmaterial is welldispersedas a fine cloud. 8.2.1 Plunge the test tube into an 800-mL beaker of ice water and continue to stir until the contents are cold. 510
@ D 3235 AIR PRESSURE ~ !
ABSORBENT
COTTON-
MERCUR~
.
FILTER )....,--I ~TO ASSEMBLY
i ~ R U B B E R STOPPER
1
WITHAIRVENT
--.---GLASSTUBINO 6-80.D;'
250mlGLASS CYI.INOER
All dimensionsare in mJllimetres FIG. 3 Air Pressure Regulator
Remove the stirrer. Remove the test tube from the ice bath, wipe dry on the outside with a cloth, and weigh to the nearest 0.1g. NOTE 5--During this operation the loss of solvent through vaporization should be less than 1%. The weight of the solvent is, therefore, practically a constant, and, after a few samples are weighed,this weight can be used as a constant factor. 8.3 Place the test tube containing the wax-solvent slurry in the cooling bath, which is maintained at -34.4 ± I*C (-30 ± 2*F). During this chilling operation stir the contents of the tube by means of a thermometer placed in the tube. It is important that stirring by means of the thermometer be almost continuous, in order to maintain a slurry of uniform consistency as the wax precipitates. Do not allow the wax to set up on the walls of the cooling vessel nor permit any lumps of wax crystals to form. Continue stirring until the temperature reaches -31.7 ± 0.3"C (-25 ± 0.5*F). 8.4 Remove the thermometer from the tube and allow it to drain momentarily into the tube, then immediately immerse in the mixture the clean, dry filter stick, which has previously been cooled by placing it in a test tube and holding at -34.4 ± l*C (-30 -+ 2*F) in the cooling bath for a minimum of 10 rain. Seat the ground-glass joint of the filter so as to make an airtight seal. Place an unstoppered weighing
bottle, previously weighed together with the glass stopper to the nearest 0.1 mg, under the delivery nozzle of the filtration assembly. NOTE 6--Take everyprecautionto ensure the accuracyof the weight of the stoppered weighingbottle. Prior to determiningthis weight, rinse the clean, dry weighing bottle and stopper with the solvent mixture described in 6.3, wipe dry on the outside with a cloth, and place in the evaporationassemblyto dry for about 5 rain. Then removethe weighing bottle and stopper, place near the balance,and allowto stand for 10 rain prior to weighing.Stopperthe bottle during this coolingperiod. Once the weighing bottle and stopper have been dried in the evaporation assembly, lift only with forceps. Take care to remove and replace the glass stopper with a light touch. 8.5 Apply air pressure to the filtration assembly and immediately collect about 4 mL of filtrate in the weighing bottle. Release the air pressure to permit the liquid to drain back slowly from the delivery nozzle. Remove the weighing bottle immediately, and stopper and weigh to the nearest 10 mg without waiting for it to come to room temperature. Unstopper the weighing bottle and place it under one of the jets in the evaporation assembly maintained at 35 ± I'C (95 ± 2*F), with the air jet centered inside the neck, and the tip 15 + 5 mm above the surface of the liquid. After the solvent has evaporated, which usually takes less than 30 min, remove the boRIc, stopper, and place near the balance. Allow to stand for 10 rain and weigh to the nearest 0.1 mg. Repeat the evaporation procedure, using 5 min evaporation periods, until the loss between successive weighings is not over 0.2 mg. 9. Calculation 9.1 Calculate the amount of extractables in the wax as follows: Solvent extractables, weight % = 100 AC/BD where: A = weight of extractables residue, g, B ffi weight of wax sample, g, C ffi weight of solvent, g, obtained by subtracting weight of test tube plus wax sample (8.1) from weight of test tube and contents (8.2), and D = weight of solvent evaporated, in g, obtained by subtracting weight of weighing bottle plus extractables residue from weight of weighing bottle plus filtrate (8.5). 10. Report 10.1 Report the result as solvent extractables, weight %, ASTM Test Method D 3235. If the result is negative, report as zero.
511
0
a2a5
o
~
HALF SECTION A-A
|
FF.RFORATEDMETAL PLATFORM 6.5 (Y4) DIA HOLES
EATI~R CONTROl.
i
ILT£R£D
HALF SECTION ' a - a ' All dimensions are in milllmetres
Orghee)
FIG. 4 Evaporation Assembly
single and independent results obtained by different operators working in different laboratories on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following values only in one case in twenty: Range Reproducibility 15to 55 % 5% 1 1.2 The procedure in this test method has no bias because the value of solvent extractables can be defined only in terms of a test method.
11. Precision and Bias 11.1 The precision of this test method as determined by statistical examination of interlaboratory results is as follows: 11.1.1 Repeatability--The difference between two test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following values only in one case in twenty: Range Rew..atability 15to55% 2% 11.1.2 Reproducibility--The difference between two
12. Keywords 12.1 petroleum waxes; solvent extractables; wax
512
~@) D 3235
APPENDIX
(Nonmandatory Information) Xl. T E S T M E T H O D OF TEST FOR M E A S U R E M E N T OF M A X I M U M PORE DIAMETER O F RIGID P O R O U S FILTERS X l . l Scope
surface tension of water and the applied pressure.
X l.l.1 This method covers the determination of the acceptability of porous filter sticks used for filtration in Method D 3235. This method establishes the maximum pore diameter and also provides a means of detecting and measuring changes which occur from continued use.
X1.4 Apparatus XI.4.1 Manometer, mercury filled and readable to 0.5 mm. XI.4.2 Air Supply, clean and filtered. X1.4.3 Air Pressure Regulator, needle-valve type. XI.4.4 Drying Oven.
Xl.2 Terminology X 1.2.1 Definition X1.2.2 maximum pore diameteruthe diameter nanometres of the largest opening in the filter.
X1.5 Procedure XI.5.1 Clean the filter sticks by soaking in concentrated hydrochloric acid, and then wash them with distilled water. Rinse with acetone, air dry, and place in drying oven at 220"F (105"C) for 30 rain. XI.5.2 Thoroughly wet the clean filter to be tested by soaking it in distilled water. XI.5.3 Assemble the apparatus as shown in Fig. XI.I. Apply pressure slowly from a source of clean air. XI.5.4 Immerse the falter just below the surface of the water. NoTE X 1.2--If a head of liquid exists above the surface of the filter, the back pressure produced must be deducted from the observed
in
NOTE X i.l--lt is recognized that the maximum pore diameter as defined herein does not necessarilyindicate the physical dimensions of the largest pore in the filter. It is further recognizedthat the pores are highly irregular in shape. Because of the irregularityin shape and other phenomena characteristicof filtration, a filter may be expected to retain all particles larger than the maximum pore diameter as defined and determined herein, and will generally retain particles which are much smaller than the determined diameter. Xl.3 Summary of Test Method X I.3.1 The filter is cleaned and wetted with water. It is then immersed in water and air pressure is applied against its upper surface until the first bubble of air passes through the filter. The maximum pore diameter is calculated from the Source of Air
pressure.
X1.5.5 Increase the air pressure to 10 m m below the acceptable pressure limit and then at a slow uniform rate of about 3 mm Hg/min until the first bubble passes through the filter. This can be conveniently observed by placing the beaker or test tube over a mirror. Read the manometer when the first bubble passes off the underside of the filter.
>e---Air Filter i:~--- Regulating Valve ::
X1.6 Calculation X 1.6.1 Calculate the pore diameter as follows:
Drying Bulb
D Filter Stick
=
2180/p
where: D -- pore diameter, nm, and p = manometer reading, m m Hg. NOTE Xl.3--From this equation, pressure corresponding to the upper and lower limits of the specifiedpore diameters can be calculated. These pressures may be used for acceptance t~tin$.
•' Manometer - ~
Beaker of Water
FIG. X1.1 Assembly of Apparatus for Checking Pore Diameter or Filter Sticks
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any ouch patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
513
(~~Ti~ Designation: D 3239 - 91
An Amencan Nahonal Standard
Standard Test Method for Aromatic Types Analysis of Gas-Oil Aromatic Fractions by High Ionizing Voltage Mass Spectrometry This standard is issued under the fixed designation D 3239; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number m parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 This test method 2 covers the determination by high ionizing voltage, low resolution mass spectrometry of 18 aromatic hydrocarbon types and 3 aromatic thiophenotypes in straight run aromatic petroleum fractions boiling within the range from 205 to 540"C (400 to 1000*F) (corrected to atmospheric pressure). Samples must be nonolefinic, must contain not more than I mass % of total sulfur, and must contain not more than 5 % nonaromatic hydrocarbons. Composition data are in volume percent.
Z78 -- 78 + 92 + 106 + 120 + . . t o end, polyisotopic + 91 + 105 + 119 + . . t o end, monoisotopic
NOTI~ I - - A l t h o u g h n a m e s are g i v e n to 15 o f the c o m p o u n d types
ZI28 = 128 + 142 + 156 + 170 + . . t o end, polyisotopic + 141 + 155 + 169 + . . t o end, monoisotopic
(I)
3. I. 1.3 Class IL" Z104 = 104 + 118 + 132 + 146 + . . t o end, polyisotopic + 117 + 131 + 145 + . . t o end, monoisotopic
(2)
3.1.1.4 Class III. ~;129 = 130 + 144 + 158 + 172 + . . t o end, polyisotoplc + 129 + 143 + 157 + 171 + . . t o end, monoisotopic
(3)
3. I. 1.5 Class IV."
determined, the presence of other compound types of the same empirical formulae is not excluded. All other compound types in the sample, unidentified by name or empirical formula, are lumped into six groups in accordance with their respective homologous series.
(4)
3.1.1.6 Class V: z i 5 4 = 154 + 168 + 182 + 196 + . . t o end, polyisotopic + 167 + 181 + 195 + . . t o end, monoisotopic
1.2 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safely and health practices and determine the applicability of regulatory limitations prior to use.
(5)
3. I. 1.7 Class VI: Z 166 = 166 + 180 + 194 + 208 + . . to end, polyisotopic + 179 + 193 + 207 + . . t o end, monoisotopic
(6)
3.1.1.8 Class VII:
1~3 The values stated in acceptable SI units are to be regarded as the standard. The values given in parentheses are provided for information purposes only.
~;178 = 178 + 192 + 206 + 220 + . . t o end, polyisotopic + 191 + 205 + 219 + . . t o end, monoisotopic
2. Referenced Documents
3.1.2 Classes, Compound Types, Empirical Formulae-See Table I.
(7)
2.1 A S T M Standards: D 2 5 4 9 Test Method for Separation of Representative Aromatics and Nonaromatics Fractions of High-Boiling Oils by Elution Chromatography 3 D 2786 Test Method for Hydrocarbon Types Analysis of Gas-Oil Saturate Fractions by High Ionizing Voltage Mass Spectrometry 3 E 137 Practice for Evaluation of Mass Spectrometers for Quantitative Analysis from a Batch Inlet 4
4. Summary of Test Method 4.1 The relative abundance of seven classes (I-VII) of aromatics in petroleum aromatic fractions is determined by mass spectrometry using a summation of peaks most characteristic of each class. Calculations are carried out by the use o f a 7 by 7 inverted matrix derived from published spectra of pure aromatic compounds. Each summation of peaks includes the polyisotopic homologous series that contains molecular ions and the monoisotopic homologous series one mass unit less than the molecular ion series. Using characteristic summations found in the monoisotopic molecular i o n - - I series of peaks, each class is further resolved to provide relative abundances of three c o m p o u n d types: nominal (Type 0), first overlap (Type l), and second overlap (Type 2). The aromatic fraction is obtained by liquid elution chromatography (see Method D 2549).
3. Terminology 3.1 Descriptions of Terms Specific to This Standard: 3.1.1 Characteristic Mass Summations--Classes I- VII: 3.1.1.2 Class I: This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Prtxtucts and Lubricants and is the direct rcsponslbdlty of Subcommittee D02.04 on Hydrocarbon Analysis. Current edition approved Oct. 15, 1991. Published December 1991. Originally published as D 3239 - 73 T. Last previous edition D 3239 - 86. : Robinson, C. J., and Cook, G. L., Analytical Chemi,stry (ANCHA), Vol 41, 1969, p. 1548. a,.lnmtal Book o/ASTM Standards, Vol 05.02. "~Annual Book of ASTM Standards', Vol 05.03.
NOTE 2--Monoisotopic peaks heights are obtained by correcting the polyisotopic heights for naturally occurring heavy isotopes, assuming that only ions of C,,H:,,+ 2 to C,,H2_~ are present. This is not strictly accurate for aromatics, but the errors introduced by such assumption are trivial. 514
~1~ O 3239 TABLE 1
Classes, Compound Types, and Empirical Formulae
Class
Type
I I I II II II Ill III III IV IV IV V
0 1 2 0 1 2 0 1 2 0 1 2 0
V V Vl VI VI VII VII VII
1 2 0 1 2 0 1 2
8. Calibration 8.1 Calibration equations in the computer program given in Table 2 may be used directly provided the following procedures are followed: 8.1.1 Instrumental Conditions--Repeller settings are adjusted to maximize the m/e 226 ion of n-hexadecane. A magnetic field is used that will permit a scan over the mass range from 78 to 700. An ionizing voltage of 70 eV and an ionizing current in the range from 10 to 70 p.A is used. NOTE 4--The instrument conditions and calibration equations described in this method are based on the use of a 180"magnetic-deflection type mass spectrometer (CEC Model 21-103). Satisfactory results have been obtained with some other magneticdeflectioninstruments. It is not known if the equations are suitable for use on all other mass spectrometer types. 8.1.2 Computer ProgramRThe FORTRAN program given in Table 2 contains all the equations for calculating the analysis, including those for calculating monoisotopic peak heights. The program is compiled and linked to create a computer load module that is available whenever needed. When the spectrum shown in Table 3 is processed, the results should agree with those shown in Table 4. 8.1.2.1 Data Input FormatRThe input format suggested in the main program may be changed to suit the needs of individual laboratories provided that true masses and peak heights are stored in the H(M) array. 8.1.2.2 FORTRAN IV Language~Changes in the program may be required for compatibility with the particular computing system to be used. These are permitted provided that the altered program gives the results shown in Table 4 with the input data of Table 3. NOTE 5--The program, as shown in Table 2, has run satisfactorilyon IBM System 360 computers.
Formula
alkylbenzenes, CnH2n.6 benzothiophenes, CnH2n.loS naphthenephenanthrenes, CnH2~.20 naphthenebenzenes, CnH2n-a pyrenes, CnH2n-22
unidentified dinaphthenebenzenes, CnH2n.10 chrysenes, CnH2n.24 unidentified naphthalenes, CnH2n.12 dibenzothiophenes, CnH~.16S unidentified acenaphthenes + dibenzofurans, C.H2n.14 and OnH2n.160
perylenes, CnH2n.28 unidentified fluorenes, CnH2n.16
dibenzanthracenes, CnH2n.3O unidentified phenanthrenes, CnH2..la naphthobenzothiophenes, CnH2,,.22S
unidentified
5. Significance and Use 5.1 A knowledge of the hydrocarbon composition of process streams and petroleum products boiling within the range 205 to 540"C (400 to 1000*F) is useful in following the effect of changes in process variables, diagnosing the source of plant upsets, and in evaluating the effect of changes in composition on product performance properties. This method, when used together with Method D 2786, provides a detailed analysis of the hydrocarbon composition of such materials. 6. Apparatus
9. Procedure 9.1 If the mass spectrometer has been in continuous operation, no additional preparation is necessary before analyzing samples. However, if the spectrometer has been turned on only recently, check its operation according to the manufacturer's instructions to ensure stability before proceeding. 9.2 Obtain the mass spectrum of the sample, scanning from mass 76 to the high-mass end of the spectrum.
6.1 Mass Spectrometer--The suitability of the mass spectrometer to be used with this method shall be proven by performance tests described both herein and in Recommended Practice E 137. 6.2 Sample Inlet System--Any inlet system may be used that permits the introduction of the sample without loss, contamination, or change in composition. The system must function in the range from 125 to 350"C to provide an appropriate sampling device. 6.3 Microburet or Constant- Volume Pipel. 6.4 Mass Spectrum Digitizer--It is recommended that a mass spectrum digitizer be used in obtaining the analysis, because it is necessary to use the heights of most of the peaks in the spectrum. Any digitizing system capable of supplying accurate mass numbers and peak heights is suitable. 6.5 Electronic Digital Computer--The computations for this analysis are not practical without the use of a computer. Any computer capable of providing approximately 60 K bytes in core and capable of compiling programs written in FORTRAN IV should be suitable.
10. Calculations 10.1 Recording Mass Spectrum--Read peak heights and the corresponding masses for all peaks in the spectrum of the sample. Use the data, along with sample identification, as input to the computer.
11. Precision and Bias 11.1 The precision of this test method as obtained by statistical examination of interlaboratory test results on a sample having the composition given in Table 5, is as follows: 11.1.1 Repeatability--The difference between successive test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material, would in the long run, in the normal and correct operation of the test method, exceed the values shown in Table 5 only in one case in twenty.
7. Reagent
7.1 n-Hexadecane NOTE 3: Warning--Combustible-Very harmful.
515
~ TABLE 2
D 3239
High Ionizing Voltage, Low Resolution Mass Spectrometric Analysis of Gas Oil Aromatic Fractions
"The "end statement" designated is specific for IBM computers. The user may modify the FORTRAN program to suit his individual needs. IN THIS PROGRAM THE VARIABLE "H(M)" REPRESENTS THE HEIGHT OF THE POLYISOTOPIC PEAK AT MASS M, THE VARIABLE "HDI(M)" IS THE HEIGHT OF THE DEISOTOPED PEAK AT MASS M, THIS IS A POSSIBLE MAIN PPOGRAM THAT REAOS INPUT DATA AND CALLS FIRST THE DEISOTOPING ROUTINE "SUBROUTINE OEISO" AND THEN THE CALCULATING AND REPORTING ROUTINE "SUBROUTINE AROMTC", COMMON TITLE(20), H(75R)~ HDI(7~B) DIMENSION MASS(B)t HITE(8) 1 READ(5~IO,~NO=gg)(TITLE(1),I=],~O) 10 FORMAT(2OA~) TITLE CARD FOR SAMPLE NAMEr ETC, PRECEDES SPECTRAL DATA CARDS, FOPMAT FOR TITLE IS 20A~ (?0 4-CHARACTER WORDS IN RO COLUMNS), FORMAT FOR SPECTRAL DATA IS MASS (16) FOLLOWED BY HEIGHT (F~,O) WITH B PEAKS PE~ RO-COLUMN CARD, DO 50 I=12,75~ H(I) = 0,0 50 HDI(1) = 0,0 30 REAO(5,40)(MASS(I),HITF(1)~I=I,~) 40 FORMAT(B(16,r4,0)) DO 50 I=I,R IF(MASS(1),Ea,aqqqqa)GO TO 60 ENTER " g g g q D q "
IN A MASS POSITION 0~; A CAPD TO DENOTE SPECTRUM END.
IF(MASS(1),EO,n)GO TO 50 M = MASS(1)
H(M) = HITF(1) 50 CONTINUE GO TO 30 ~0 CALL DEISO CALL ARONTC ~0 TO 1 ,,GO TO I " ALLOWS SUCCESSIVE SAMPLES TO BE COMPUTEr BEFORE RELEASING COMPUTE R,
99 STOP ENn SUBROUTINE DEISO THIS ~URROUTINE COMPUTES MONOISOTOPlC PEAKS ASSUMING ALL IONS HAVE Z NIIMREPS FROM +2 TO - ] ! IN THE FORMULA C(N)H(2N + Z), COMMON TITLE(20), H(758)~ HDI(75B) ~IMENSION NCAQR(75R)~ NHYD(75R) DO I0 I=12,758 NCARR(1) = 0 I0 NHYO(1) = 0 O0 20 K=12,75R NCARR(K) = (K + 11}/14 NHYD(K) = K - 12*NCARB(K) IF(NHYn(K).LT,O)NHYD(K) = 0 2O CONTINUE DO 30 K=I4,TSR HDI(K) = H(K)-HDI(K-I)~(.OIOBII*FLOAT(NCARB(K-I))+,OOOI5*FLOAT I(NHYD(K-I))) HOI(K) = HDI(K)+HDI(K-2)*(,OOOOSB~4OFLOAT(NCAQB(K-2)t(I-NCARB(K-2) I))+.IIPSE-7*FLOAT(NHYO(K-2)*(I-NHYD(K-~)))-,16PI65E-SoVLOAT(NCARR( 2K-~)*NHYD(K-~)}) IF(HDI(K),LT,O,O)HDI(K) = 0.0 30 CONTINUE RETURN END
516
~
D 3239
TABLE 2
Continued
SUBROUTINE AROMTC C C THIS QOUTINE GIVES THE ANALYSIS OF AROMATICS FRACTIONS FROM PETROLEUM C USING THE RRnCEDURE DESCRIBED IN ANAL CHEM 41t 1 5 4 8 - 5 4 ( 1 9 6 9 ) C COMMON T I T L E ( 2 0 ) ~
H(75R)t
HOI(758)
DIMENSION A/N(797), ~ A t 7 ) t BB(7)~ SR(75R) DATA AIN / + 1 . 8 0 q ~ , - . l q 5 2 ~ + . O l ~ 4 , - . O O Z I , - . O O l S , - . O n 1 1 , - . O 0 2 ~ , 2 -.1601.+2.047qt-.2806~-.O~Ol.+.OOB2,+.On]2,+.o00~.
C C
3
-.0943,-.2287~+2.~024,-.4q3~,-.0601~-.01559-.00~,
4 5 6
-.0292~*.0033,-.N580,+1.9404,-.1337,-.0]17,-.0043,
7
-.2346~-,106Q,-.O267,-.OOlq~-.O057,-,0904~+l.9904/
-.On~2t-,O003,-oO026,-.O195,+].9773,-.l~23,+.0123~
-.0420~÷,O0~6,-.OOlS,-.OlSl,-.O~84,÷?,0616t-.41q3, INITIALIZE SQUARE RO~T ARPAY
C DO 2132 I=]2,750 2132 SP(I) = 0.0 ASSEMBLE APPROPRIATT P~AKS IN ~ASS SPECTRUM OF AROMATIC FPACTIhN FOR PROCESSING IN A 7 X 7 MATRIX. QUANTITIES A6~aI~AS,ETC, REFER INITIALLY TO SUMS OF PEAKS AT Z NUMBERS 6~7~8,ETC. A6~AB,~TC. ARE LATER REDEFINED TO INCLUDE THE ODD Z-NUMBER SUM CORRESPONDING TO THE PARENT-] SERIES (A6 = A6 ÷ A7, AR = A8 ÷ AQ, ETC.)
2106
2107
A6 O0 A6 A7 00 AT A6
= 0.0 2106 : A6 : 0,0 2107 = A7 = A6
A~. =
H:78,750tZ4 + H(M) M=91~7~0~14 ÷ HDI(M} ÷ A7
0,0
DO 210R M=104~750,14 2lOB
A8
=
A8
÷
H(M)
A9 00 ;)109 A ¢) A8
2110
;)111
: 0,0 2109 M = 1 1 7 , 7 5 0 , 1 4 = A9 ÷ H O I ( M ) = AR * A9 A|O = 0 . 0 DO 2110 M = 1 3 0 , 7 5 0 , 1 4 AIO= AIO+ H(M) A l l = 0.0 00 2 1 1 1 M = 1 2 c J , 7 5 0 , 1 4 All = A11 + HOI(M) AIO
2112
2113
=
AIO
+
Al1
A12 = 0 , 0 DO 2 1 1 2 M = I 2 8 t 7 5 0 ~ I 4 A12 = A12 * H(M) A13 = 0o0 DO 2113 M = 1 4 1 , 7 5 0 ~ 1 4 AI3 = AI3 ÷ HDI(M) A12 = AI2 * AI3
A14 = 0.0 qO 2114 M=154t750,14 2114 AI4 = A14 + H(M) AI~ = 0 ° 0 00 2115 M=167,750,14 2115
2116
2117
AI5 = AI5 + HOI(M) AI~ = A]4 ÷ AI5 A16 = 0 . 0 DO 2116 M = 1 6 6 4 7 5 0 , 1 4 A16 = A I 6 * H(M) AI7 = 0.0 DO 2117 M=179.750~14 A17 = A17 + H O I ( M ) A I 6 = A16 + A17
A]~ = 0.0 DO 2118 M = | 7 R , 7 5 0 , 1 4 2118
A1R = A18 + H(M) Alq = 0.0 DO 2 ] l q M : 1 9 1 , 7 5 0 , 1 4
517
~)
D 3239
TABLE 2 2119 C C C C
Continued
Alg = Alg + HDI(M) Aln = Al8÷ Alg CORRECT TH~ PEAK SUMS FOR THE PRESENCE OF IRRELEVANT IONS AT MASSES 175,176,IR9,1o0,200,21~ CO1175 =HDI(I~I)-(HDI(I61)-HDI(?03})/3.O IF(HOI(I75).GE.CDII75) GO TO I 0 ~ 6 CDII?S = MOI(175)
C C C C
ABnVE STATFMENTS CORRECT HDI(175) NEXT STATEMENTS CORRECT H(176) 1046
C C C 1048
C C C
CHIT6 = H(I62)-(H(162)-H(204))/3.0 Ir(H(176).GE.CHI76)GO TO 1048 CH176 = H(176) NEXT STATEMENTS CORRECT HDI(189) CDII89 = COIl75 - (CDIITS-HOI(203))/2.0 IF(HDI(IB9).GE.COIIR9)GO TO 104q CDI1@9 = HnI(IR9)
NEXT STATEMENTS CORRECT H ( 1 9 0 ) 1049
CHIgO = C H | T 6 - ( C H 1 7 6 - H ( ? 0 4 ) ) / 2 . 0 IF(H(I90).GE.CHlOO) GO TO 2 1 0 I CH]90 = H ( ] g O )
C NEXT STATEMENTS CORRECT H ( 2 0 0 ) C C 2101 CH200 = ( H ( 1 8 6 ) * H ( ? I 4 ) ) / 2 . 0 I F ( H ( 2 O O ] . G E o C H 2 0 0 ) GO TO ?|OP CH200 = H(~O0) C NEXT STATEMENTS CORRECT H D I ( 2 1 3 ) C C 2102 CDI213 = ( H ~ I ( I O g ) * H D I ( ? 2 ? ) ) / 2 . O IF(HDI(213).GE.CDI213) GO TO 2103 COl213 = H D I ( 2 ] 3 ) C NEXT STATEMENTS CORRECT THE A 6 t A 8 o E T C . SUMS C C 2103 A6 =A6-(HOI(175)*HDI(IB9) +H(]?6)+H(IO0)) I *CDIITS
*CDIIR9÷
CHI?6*
CHI90
AlO= AIO-(H(?OO)*HDI(213))*CH2OO*CDI213 REDEFINE A~,A~,ETC. AS SUBSCRIPTED VARIARLE AND MULTIPLY BY THE AROMATICS INVERSE A I N ( I t J ) RA(1) = A6 RA(2) = A8 qa(3)
=AlO
BA(4) = AIP ~ A ( S ) = A14 BA(6) = A I R BA(7) = A I ~ O0 2125 J = 1 , 7 ~q(J)=O°O 00 2124 I = 1 , 7
2124 2125 CONTINUE ~0 E127 J = l , ? IF(BB(J))El?S,PI27,2127 2126 ~R(J)=O°O 2127 CONTINUE AA6 = 8 R [ 1 ) AAA
=
~R(2)
AAIO = B B ( 3 ) ~ A I 2 = 88(4) AA]4 = B8(~) AA]6 = BB(~) AAI8 = RB(7) SUMAA = 0*0 DO 212B J = l , 7
518
~
D 3239
TABLE 2 2128 C C C C C C
SUMAA =
Continued
SUMAA*PR(J)
VALUES OF AA6,AA8~ETC. ARE DIVISIONS CALCULATED FOR NOMINAL Z=-6~ -~,ETC. SUMAA IS SUM OF THE AA VALUES AND REPRESENTS THE TOTAL DIVISIONS OF AROMATICS CALCULATED. THE FOLLOWING STATEMENTS RESOLVE OVERLAPPING TYPES IN Z = -6~ A7 : AT-HDI(17S)-HDI(IRQ)+CDII7S÷CDII89 HOI(17S)=CnII?5 HOI(IBg)=CDII89 DO 2 1 3 0 M = 1 0 5 , 7 5 0 , 1 4 IF(HDI(M))~130~2131~2130 2 1 3 0 CONTINUE 2 1 3 1 MM : M - 1 4 SLOPE : ( ( ( O . 7 ~ * H D I ( I O S ) ) * * O . 5 ) - ( H D I ( M ~ ) ) * * 0 . 5 ) / I (90.7I-(IO00.O/rLOAT(MM))**2) B = (O.72*HOI(IOS))**O.5-QO.7]*SLOPE DO 2133 M=I47.MM~I4 ~EALM = M +B 2 1 3 3 SR(M) : S L O P E * ( I O O O , O / R E A L M ) * * 2
C C C C
ABOVE IS FO~ Z = - 6 AND STORES SQUARE ROOTS OF ALKYL BENZENE OEAK HEIGHTS IN ARRAY 5R(I).R~LOW IS rOB Z = -B
DO 213~ M=PI5.7SO~14 IF(HDI(M))?134.2135~2134 2 1 3 4 CONTINUE 2 1 3 5 MN = M-14 SLOPF = ( ( ( O . 6 6 * H D I ( 1 7 3 } ) * * O . S ) - ( H O I ( M N ) ) * * O . 5 ) / (34.12 -(IO00.O/CLOAT(MN))**2) B : (0.66*HDI(173))**O.5-34.I2*SLOPE DO 2 1 3 6 M = ? I S ~ M N ~ I 4 REALM : M 2136 SP(M) = SLOPE*(IOOO.O/REAL~)**? +@ C C C
BELOW IS FnR Z = - I 0
A l l = A l l - HDI(PI3)*COI213 H01(213) = C01213 DO 2137 M=?41tTSO.14 Ir(HDI(M))P]37,2138,2137 2 1 3 7 CONTINUE 2 1 3 8 MO = M - 1 4 SLOPE = ( ( H ~ I ( I R S ) ) * * O , S - ( H ~ I ( M O ) ) ~ O , ~ ) / 1 (2g,22-(lOOO,O/~LOAT(MO))**2) B= H D I ( 1 8 5 ) * * O , 5 - 2g,~?*SLOPE DO 2 1 3 9 M = ? 4 1 ~ M O ~ I 4 REALM = M 2 1 3 9 SR(M) : SLhPE*(IOOO.O/REAL~)**~÷B C BELOW I S FOR Z = - 1 2 C C 00 2140 M:]97.750~14 IF(HDI(M))?I40,2141,2140 2 1 4 0 CONTINUE 2 1 4 1 qP = M-14 SLOPE = ( ( ( O . 2 5 * H D I ( I B 3 ) ) * * O . 5 ) - ( H O I ( M P ) ) * * O . 5 ) / l (29.8&-(InOO.O/FLOAT(MP))**2) B = (0,25"WDI(183))**0.5 - 29,S&*SLOPE
DO 2 1 4 2 M=]97~MP~14 2142 C C C
REALM = M SR(M) = SLOOE*(IOOO.O/REALM)**2+B BELOW IS FnR Z = -14
00 2143 M=765,750,14 IF(HOI(M))?I43.2144,2143 2 1 4 3 CONTINUE 2 1 4 4 MQ = M-14 SLOPE = ( ( ( O . 6 4 * H D I ( 2 5 1 } ) * * O . 5 ) - ( H O I ( M Q ) ) * * O . 5 ) / 1 (IS.RT-(INOO.O/FLOAT(MQ))**2) B : ( 0 . 6 4 " H D I ( 2 5 1 ) ) * * 0 . 5 - 15.RT*SLOPE
519
~ TABLE
2145 C C C
D 3239 2
Continued
DO 2145 M=P65,MO~I4 REALM = M SR(M) = SLO~E*(IOOO.O/~EALM)**2÷B RELOW IS FOR Z = - 1 6
O0 2 1 4 6 M = 7 9 1 ~ 7 5 0 , 1 4 IF(HDI(M))PI46,2147,2146 2 1 A 6 CONTINUE 2 1 4 7 MO = M - 1 4 SLOPE = ( ( ( O . 7 * H D I ( 2 7 7 ) ) * * O . 5 ) - ( H O I ( M R ) ) * * O . 5 ) / 1 (I3.03-(IO00.O/rLOAT(MR))**2) B = (O.7~HOI(277))**O.5-I3.03*SLOPE DO 2 1 4 ~ M = ~ 9 1 ) M R ) 1 4 REaL M = H 2148 S ~ { M ) = S L O P E ~ i l O O O . O / R E A L M ) t * 2 ÷ ~
C C C
qELOW IS FOR Z = -18
O0 2 1 4 9 M = ~ 7 . 7 5 0 ~ 1 4 IF(HDI(M) )214a,~150,2I~9 2 1 4 0 CONTINUE 2150 ~S = M-14 SLOPE = ( ( ( 0 . S A * H D I ( 2 3 3 ) ) * * 0 , 5 ) - ( H O I ( W S ) ) * * 0 , 5 ) / 1 (18.42-(IO00.O/FLOAT(MS))**2) R = (O.58*MOI(P33))**O.5-18.42*SLOPE 00 2 1 5 1 M = P ~ T ~ M S ~ 1 4 REALM = M 2151 5~(M) = SLOPE*(IOOO.O/~EALM)**?+~ C THE SQUARE ROOT ARRAY HAS qEEN CALCUL~TEO. FOR CERTAIN SPECTRa IT C MAY BE PO~SIRLE TO GET SLOPE AN~ INTERCEPT VALUES I N REGIONS OF C ZERO PEAK H E I G H T . I F T H I S OCCURSt ERRORS HIGHT BE ENTERED I N THE C SR &RRAY. THE FOLLOWING SETS ~R TO ZErO AT MASSES WHERE H D I = O . O C C 00 2153 I=12,750 Ir(HOI(I)) 2152,2152~2153 2152 SR(I) = 0.0 2 1 5 3 CONTINUE C THE SR ARRAY IS SQUARED TO GIVE UNCOPQECTED PEAK HEIGHTS OF THE C NOMINAL Z TYPES C C DO 2 1 5 4 I = I 2 , 7 ~ 0 =(S~(I)**2) 2154 SP(I) C CORRECT CERTAIN VALUES IN S R ( I ) FOR NONLINEARITY OF Sq RT RELATION C C SR{147) = SR(I~T)Ol.a~ SP(197) = SR(lq7)°3,10 SP(211) = SR(211)'2,52 S~(225) = 5P(~25)'2,07 S~(23q) = ~R(23q)Ql,83 SR(253) = SR(253)*].59 SR(267} = SR(267)*l.39 SR(2R[) = ~R(281)*1.28 SR(295) = ~R(2QG)*1oP6 55(309) = RR(309)*1.14 Sq(323) = $R(323)'1°06 S0(265) = SR(2~5)~].42 SP(279) = ~P(~Tg)*I.~4 ~Q(293) = ~R(203)*1.]2 SR(307) = 59(307)*1.06 SR(291} = SP(291)*1°24 SR(305) = SR(305)*1.15 SR(319) = SR(319)'1,07 SP(333} = ~R(333)'1.06 SR(347) = ~R(347)*1.05 5R(361) = SR(361)*I,03 SP(247} = ¢R(~47}*1.61 S~(2&I) = SR(P~I)*I.50 5P(275) = ~R(275)*1.44 SR(289) = ~R(289)*1o37 SR(303) = ~R(303)*1.28
520
~
D 3239 Continued
TABLE 2
SR(317) SR(331) SP(3~S) SQ(359) SR(373) SP(387)
2155 2156 C C C
= = = = = =
SP(317)*1o28 qR(331)~1.21 SR(345)~1,10 ~Q(359)~I.09 ~R(373)#I°07 SR(387)~I.05
IT IS NECESSARY THAT NO VALUE SR(~) EXCEEDS THE CORRESPONDING VALUE HDI(M) O0 2 1 5 6 M = 1 2 t 7 5 0 IF(SR(M)-HnI(~))~]56,2156,~lSS SR(M) = HDI(M) CONTINUE CALCULATE PORTIONS OF A7 DUE TO A6AtA]OS.A20A AND OTHER TYPES
2157 2158
A6A = 0 . 0 DO 2 1 5 7 M = q l . 1 3 3 , 1 4 A6A = A 6 A + H O I ( M ) DO 2 1 5 8 M = 1 4 7 ~ M M , l ~ A6A = A 6 A ~ R ( M ) AIOS = 0.0 DO 2 1 5 9 H=147o189,14
2]50
2160 2161 C C C
AIOS = AlO5 + HOT(M) AIOS = A105/.75 A20A = A 7 - A 6 A - A I O ~ IV(A20A)2160,2161t2]61 A20A = 0 . 0 AlflS = A7-A6A CONTINUE
SR(M)
CALCULATE DIVISIONS OF A6AeAIOS,AND A20A TRASH = ( A 6 - A A 6 ~ . 5 5 7 9 ) ~ ( A 7 / A 6 ) Ir(TRASH,LT,O,O)TRASH = 0,0 A7 = A7 - TRASH IF(AT.LE.O.O)A7 = 1.0 A6A = A6A - TRASH IF(A6A.LT.O.O)A6A = 0 o 0 Ir(A~A.EQ.O.O)A7=AIOS*A20A A6a = ( A 6 A / A T ) ~ A A 6 A1flS = (AIOS/AT)~AA6 A20A = (A2OA/AT)~AA6
CALCULATE PORTIONS OF A9 DUE TO ABA~A?~A,AND OTHEQ TYPES
2162 2163
2164
ARA = 0°0 DO 2 1 6 2 M = 1 1 7 , 2 0 1 , 1 4 ASA = A8A÷~DI(M) DO 2 1 6 3 M = ~ I S , M N ~ ] 4 ASA = ASA÷FR(M) A22A = 0 . 0 DO 2 1 6 4 M = ~ 1 5 t 2 5 7 , 1 4 A2?A = A22A • HDI(H) A~A = A22A/,75 A3~A = A 9 - A R A - A 2 ~ A
-
SR(~)
Ir(A36A)2165,2166,216~
C C C
2165
A36A
2166
A2~A : A g - A S A CONTINUE
=
0,0
CALCULATE nIVISIONS
OF ABA,A2~AtAND OTHER TYPES
TRASH : (AR-AAR~.Aqq7)e(Aq/AR) Ir(TRASH.LT.O.O)TRASH = 0 , 0 AQ = Aq - TRASH IF(A9.LE.O°O)AQ : I . 0 ARA : A~A - TRASH I~(ASAeLTe~eO)A8A = 0.0 IF(ASA.EQ,O,O)Ag=A2?A~A36A ARA = ( A S A / A g ) ~ A A ~ A22A = (A2~A/Ag)~AAR A36A = ( A 3 A A / A q ) ~ A A 8
521
~
D 3239
TABLE 2
CALCULATE PORTIONS OF A l l
Continued
DUE TO AIOA,A24AtAND OTHER TYPES
AIOA = 0.0 O0 2167 H=129.~27,14 2167 AIOA = AIOA*HDI(M) DO 2 1 6 8 M=~41,MO,I4 2168 AI~A = AIOA*SR(~) A~&A = 0 , 0 DO 2 1 6 9 M f P 4 1 , ~ 8 3 , 1 ~ SR(M) 2 1 6 9 A2~A = A24A * H O I ( M ) A24A = A 2 ~ A / , 7 5 A38A = A I I - A I O A - A 2 ~ A IF(A38A)2170,2171,2171 2170 A3RA = 0 , 0 A2~A = A l l - A I O A 2171 CONTINUE C CALCULATE DIVISIONS OF AIOA.A24A,AND OTHER TYPES C C TRASH = ( A 1 O - A A I O * . 4 4 3 S ) * ( A l l / A ] O ) Ir(TRASH.LT.O.~)TRASH = 0.0 A l l = A l l - TRASH I F ( ~ I I . L E . O . O ) A I I = 1.0 AIOA = AIOA - TRASH IF(AIOA.LT,O,O)AIOA = 0.0 I~(AIOA.EO.O.O)AII=A24A*A3~A AIOA = ( A I O A / A I ] ) * A A ] O A24A = ( A 2 4 A / A 1 ] ) * A A l O A3AA = ( A 3 ~ A / A I I ) * A A I O -
CALCULATE PORTIONS Or AI3 DUE TO AI2A,AI6StAND
2172 2173
2174
2175 2176 C C C
OTHER TYPES
AI2A = 0 . 0 00 2172 M = 1 4 1 . 1 8 3 , 1 ~ A I 2 A = AX2A÷HOI(M) DO 2 1 7 3 M f ] 9 7 , M P t I 4 AI~A = AI2A*SR(M) A I 6 S = 0.0 DO 2 1 7 ~ M = I Q T , p 2 5 , 1 4 A I ~ S = Al6~ ÷ H O I ( M ) - SR(w) AI6S = A16~/o6~5 A26A = AI3-A12A-AI6S IF(A26A)2175,2176,2]76 A 2 6 A = 0.0 A I 6 S = AI3-AI2A CONTINUE CALCULATE nIVISIONS
Or AI2A,A16StA26A
T~ASH = ( A I 2 - A A I ? * . S l g ? ) * ( A I 3 / A 1 2 ) IF(TRASH.LT.O.o)TRASH = 0 . 0 A13 = AI3 - TQASH I r ( A I 3 . L E . O . O ) A I 3 = 1.0 AI2A = AI2A - TRASH I r ( A I 2 A . L T . O . O ) A ] 2 A = 0.0 IF(AI2A.EQ.O.O)AI3=A16~*A26A AI2A : (AI~A/A13)*AA12 A16S = ( A I 6 S / A I 3 ) O A A ] 2 A~6A = ( A 2 6 A / A 1 3 ) e A A ] 2 CALCULATE PORTION OF AIS DUE TO AI4AtA~BAtAND OTHER TYPES
2177 2178
A I 4 A = 0.0 DO 2 1 7 7 M = 1 6 7 , ~ 5 1 . 1 4 AI4A = AI~A+HOT(M) DO 2 1 7 8 M = ? 6 5 , M O , 1 4 AI4A = AI4A*SR(M) A2~A
2179
=
0,0
DO 2 1 7 9 M = ~ 6 5 , 3 0 7 , 1 4 A?~A = A2~A * H D I ( M ) A28A = A 2 8 A / , 7 5 A4~A = A 1 5 - A 1 4 A - A 2 8 A
SR(M)
522
I{~) V 3239 TABLE 2
2180 21B1 C C
Continued
IF(A42A)21AO*2181,2181 A42A = 0,0 A2RA = A 1 s - A I ~ A CONTINUE
CALCULATE DIVISIONS OF AI4A,A2AA.ANO OTHER TYPES
C TRASH = ( A I 4 - A A I ~ * . 5 0 7 5 ) ~ ( A l S / A I ~ ) Ir(TRASH.LT.O.O)TRASH = 0.0 AIS = A15 - TRASH I F ( A I 5 . L E . O . O ) A I 5 = 1.0 AI4A = AI4A - TRASH I F ( A I 4 A . L T . O . O ) A 1 4 A = 0o0 IF(AI4A°EQ.O.O)AIS=A28A+A42A AI4A = (Al~A/AlS)~AA14
C C C
A2AA
=
(A2~A/A15)*AA|4
A42A
=
(A4~A/AIS)~AA14
CALCULATE PORTIONS OF AI7 DUE TO A16AtA30A,ANO OTHER TYPES
A16A = 0,0 DO 2 1 8 2 M = 1 7 9 , 2 7 7 t 1 4 2 1 8 2 AI6A = AIAA+HOI(M) DO 2 1 8 3 M = ~ g l , M R , 1 4 2183 AIAA = A16A÷SR(M) A30A = 0,0 00 2 1 8 4 ~ = 2 9 1 , 3 3 3 , 1 4 2 1 8 4 A30A = A30A + HDI(M) - SR(~) A3flA = A30A/.75 A44A = AIT-AlAA-A30A IF(A&&A)21RSt2186t2186 2 1 8 5 A 4 4 A = 0.0 A30A = A17-AlAA 2 1 8 6 CONTINUE C CALCULATE nIVISIONS OF AIAA,A30A~AND OTHER TYPES C C TRASH = ( A l A - A A 1 6 ~ . 4 9 1 0 ) * ( A l T / A I 6 ) IF(TRASH.LT.O.O)TRASH = 0.0 AI7 = A17 - T~ASH I r ( A 1 7 . L E . O - O ) A I 7 = 1.0 A I 6 A = A 1 6 A - TRASH IF(A16AoLT.O,O)A16A = 0.0 TF(AI6A.EQ.O°O)AI7=A30A+A4~A A16A = (AIAA/AI7)~AA16 A30A = (A3~A/A17)~AA16 A4&A = ( A 4 4 A / A I T ) ~ A A 1 6
CALCULATE PORTIONS Or A ] 9
2187 2188
2189
2190 2191 C C C
A 1 8 A = 0.0 O0 2 1 8 7 M = 1 9 1 , 2 3 3 , 1 4 A18A = A18A+HDI(M) O0 2 1 8 8 M = 2 4 7 , M S , 1 4 AIRA = A18A÷SR(M) A2~S = 0.0 DO 2 1 8 q M=p47.28q~14 A2~S = A22~ ÷ HDI(M) A~PS : A 2 ~ R / ° 7 5 A3~A = AIg-AIRA-A~?S IF(A32A)21aOt2|91121ql A3?A = 0.0 A~2S = AI9-AIAA CONTINUE
-
DUE TO A I 8 A t A 2 ~ S t A 3 2 A
SR(~)
CALCULATE DIVISIONS OF AISA.A22StAND OTHER TYPES TRASH = ( A I B - A A I R ~ . S O T 3 ) i ( A I g / A ] 8 ) Ir(TRASH.LT.O.O)TRASH = 0 , 0 Alq'= A 1 9 - TRASH IF(A|9.LE.O.O)AIq = ].0 AIRA = AISA - TRASH I F ( A | S A . L T . O . O ) A I R A = 0,0 TF(AISA.EQ.O.O)AIg=A22$÷A3~A AIRA = (Al~A/AIg)~AA18 A2~S = (A2~S/AI9)*AA18 A32A = (A3?AIAIg)~AA18
523
~
D 3239
TABLE 2
Continued
THIS COMPLETES CALCULATION OF AROMATICS BREAKDOWN VOLUME PERCENTS ARE NEXT CALCULATED V6A = ]O0.~*A6A/SUMAA VI~ = IO0.O*AIOS/SUMAA V 2 0 A = IO0.O*A~OA/SUMAA
V~A = IO0.O~ABA/SUMAA V22A : IO0.O*A2?A/SUMAA V 3 6 A : IO0.OiA36A/SUMAA V I O A = IO0.O*AIOA/SUMAA V2~A = IO0.O*A?AA/SUMAA V3RA = IO0.O*A38A/SUMAA VI2A = IO0.O*AI2A/SUMAA VI6S = IO0,O*AI6S/SUMAA V~6A = IO0°O*A?6A/SUMAA VI6A = IO0.O*AI4A/SUMAA V2BA = |O0.O*A28A/SUMAA V~A = IO0.O*AA2A/SUMAA VI6A = IO0,O*AI6A/SUMAA V30A = IO0.O*A3OA/SUMAA V~A = IO0°O*A~A/SUMAA VIBA = IO0.O*AIBA/SUMAA V2~S = |O0°O*A?2S/SUMAA V32A = IO0,O*A32A/SUMAA AMONO = A6A÷ARA~AlOA VMONO = V6A÷V~A*VlOA ADI = Al2A*Al4A÷AIGA VOI = VI2A*VI~A÷VI6A ATRI = AIRA*A20A VTRI = VISA-V20A ATET~A = A~2A~A2~A VTETRA = V ~ A ÷ V 2 ~ A APENTA = A ? ~ A * A 3 0 A VPENTA = V ~ R A + V 3 0 A ATMIO = AIOS~A]6S*A~S VTHIO = VIOS÷VI6S÷VP2S AUNID = A 3 6 A * A 3 8 A ÷ A 2 6 A ÷ A ~ A + A ~ A A + A 3 2 A VUNIO : V36A÷V38A+V~6A+V~2A+VA~A+V32A
WRITE WRITE WRITE WRITE WRITE W~ITE WRITE WRITE WPITE |
(6~2~00)
(6,2SOI)(TITLE(I)~I=It20) (6t2SO2)AMONO,VMONO,A6A~V6AtASA,VRA,AIOA,VIoA (6~2S03)ADI,VOI,AI2A,VI2A,AI4AtVI4AtAI6A,VI6A (6,2~04)ATPI,VTRI,AIBA,VIRAtA~OA,V?OA (6~2505)ATETRA,VTETRAtA2?A,V~2A,A24A~V2~A (6,2S06)~PENTA,VPENTAtA2~A~V28AtA30AtV30A (6t2~O7)ATHIOtVTMIO,AIOS,VIOS,AI6S,V16S,A22~,V2~S (6t2~OS)AUNIDtVUNID~A36A,V36AtA38A,V3~AtA26&~V26A~A~2A,V42At
A~AtV44A,A32AtV32A
2500 FORMAT (IHI 9X,44HMASS SPECTRAL ANALYSIS OF AROMATIc FRACTIONS) 2501
FORMAT
(IHO,2OA41/3RX,PTHCALCo I O N SUMS
VOLUME PCT)
(]HO,SX.13HMONOAROMATICSt24X,F7°O~6XtF7°I/IOXtI3HALKYL~ENZE INES~ISXtF7.0,6X,FT,I/IOX,ITHNAPHTHENEQENZENEStIIX,F7.0,6X,F7.I/
2502 FOQMAT
2IOX,IgHDINAPHTHENERENZENES,gX,FT.O,6XtF7.I) FORMAT (lHO,SX,IIHDIAROMATICS,26X,F7.O,~X,FT°I/IOX~12HNAPHTHALENES I,I~XtF7,O,~XtFT.I/IOX,pBHACENA~HTHENES, OIBENZOFURANS,F7,0,6X.FT.I 2/IOX,gHFLUDRENFStIgX,E7oO,6XtF7°I) 2506 FORMAT (IHOt8X,12HTRIAPOMATICS,~SX,F7.0,GX,FT°I/IOX,13HPHENANTHREN IES,ISX,FT.O,GX,F7.I/IOX~22HNARHTHENEPHENANTHRENES,6X,FT.O,6XtF7.I) 2505 FORMAT (IHO,SX,14HTETRAARO~ATICS,23XtF?,O~6XtF?.I/IOX,THPYRENES,21 IX,rT°O,6X,F7°I/IOX,9HCHRYSENES,I9X,FT.O,GX,F7.I) 2506 FORMAT (IHO,RX,14MPENTAAROMATICS~?3XtFT.O,6XtFT°I/IOX,gHPERYLENES, llgX,F7.0,6X,F7.1/IOX,17HOIBENZANTHRACENEStliX,FT.O,6XtFT,I) 2507 FORMAT (IHO,BX,IgHTHIOPMENO AROMATICSt]BX~FT.O,6X,FT.I/IOX,ISHRENZ IOTHIOPHENES,13XtFT°Ot6X,F7,I/IOX~I7HOIRENZOTHIOPHENES,IIXtF?.O~6X, 2FT.I/IOXt2?HNAPHTHOBENZOTHIOPHENES,6XtF7.0,6X,F7°I) 2508 FORMAT (IHfl,SX,22HUNIOENTIFIED AROMATICS,lSXtFT.O,6XtFT.I/IOXt37HC ILASS I INCL WITH NAPH PHENANTMRENES/IOX,BHCLASS IIt2OXtF?.Ot6X,F7 2.I/IOXtgHCLASS III,19XFT.O,6Xt~7.I/IOXtBMCLASS IV,2OX,FT,O,6X,F?,I 3/lnX,THCLASS V,21X,FT.Ot6X,FT.I/IOXtBHCLASS VI,?Ox,FT°OtGX,F7.1/IO 4X,gHCLASS V I I , I g X , F T . O , 6 X , r T , I ) RETURN END 2503
524
~) D 3239 TABLE 3 MASS HT
MASS HT 78 126 86 46 94 93 102 92 11o 68
79 87 95 103 111
118 126 134 142 1S0
270 13# 2~5 297 83
158 166 174 182 190
PC-69-378 Test Spectrum for Gas Oil Aromatics Analysis MASS HT
332 77 ~80 127 143
M A S ~ HT
M A q S HT
H A S ~ HT
M A ~ S HT
MASS HT
80 98 ~P 72 96 108 104 174 112 ~5
81 89 97 |05 113
610 l~O 30] 98~ 13~
82 128 90 35 98 62 106 387 114 117
83 91 99 ]07 115
532 694 53 ]87 402
84 76 92 210 I00 54 108 107 116 ] 9 4
85 93 lO1 109 117
181 216 158 264 40~
1191045 127 175 135 112 1#3 496 151 140
120 128 136 144 1~2
389 407 47 2R9 247
121 129 137 145 153
16# 482 98 739 229
172 70 ] 3 0 287 138 78 I#6 212 154 163
123 131 139 I#7 15~
152 659 ]46 289 486
1~4 48 132 272 140 72 148 102 156 p 6 4
125 133 141 149 157
I04 66~ 406 94 438
226 2O4 106 160 143
159 167 175 183 191
53~ 268 ]25 280 297
160 168 ]76 184 ]92
144 180 1P9 134 262
161 159 177 185 193
161 43# 10# ?26 380
162 70 170 209 178 334 1~6 98 194 200
163 171 179 187 195
119 318 #14 218 318
16# 76 172 140 180 204 la~ 96 19~ 132
165 173 181 189 197
477 316 312 306 191
198 98 206 25~ 214 03 222 133 230 206
I~9 207 215 223 231
179 316 374 169 244
200 208 216 224 23?
112 171 213 124 171
201 209 217 225 233
158 ?~0 225 ]5# ]97
~02 ~I0 218 226 234
300 117 156 184 162
203 211 ?19 227 235
253 168 269 181 172
204 212 220 228 236
144 90 216 2OO 112
205 213 221 229 237
307 198 238 320 150
238 246 2~4 262 270
113 ]67 124 121 1~
239 247 255 263 271
257 153 178 145 144
240 248 256 264 272
136 130 172 I~4 144
241 24q 257 265 273
189 ]3# ]90 162 11#
24? 250 258 ~66 274
174 132 173 ]56 1#2
243 25] 259 267 275
251 118 156 153 105
244 252 260 268 276
196 192 152 128 149
~4~ 253 261 269 277
214 ~00 131 156 115
278 286 294 302 310
130 127 134 127 120
279 136 287 97 295 115 303 93 311 92
280 288 296 304 312
143 124 127 Ill 116
2B1 ] 3 3 289 ] I # 297 108 305 85 313 91
282 ?90 298 306 314
132 123 129 122 ]20
283 127 291 94 299 95 307 93 315 78
284 292 300 308 316
133 125 130 123 116
285 11~ 293 112 301 82 309 95 317 77
318 326 334 342 350
106 118 109 II0 108
319 327 335 343 351
78 78 78 62 69
320 328 336 344 352
116 llS 108 107 104
321 329 337 345 353
8] 69 73 61 67
327 330 338 3#6 354
llS 112 108 98 100
323 331 339 347 359
80 68 75 61 57
324 332 340 348 356
118 101 108 102 104
325 333 341 349 357
82 69 67 75 56
358 102 366 104 374 84 382 88 390 aO
359 367 375 383 391
54 63, 47 49 47
360 368 376 384 392
o2 96 ~8 91 84
361 369 377 385 393
54 56 54 #6 #8
362 370 378 386 394
96 98 90 87 84
363 37] 379 387 395
'69 50 55 44 48
364 102 372 95 380 90 3q8 76 396 80
365 373 381 389 397
73 49 54 43 45
398 406 414 422 430
84 76 76 %~ ~4
300 407 415 423 431
42 42 38 38 30
400 408 416 424 432
Rl 75 60 ~4 56
401 409 417 425 431
#1 #2 34 36 3~
#0 ~ #10 #18 426 #36
67 72 53 69 59
403 411 419 #27 435
38 40 34 34 33
404 412 4~0 428 436
70 77 66 66 59
405 413 421 429 437
41 38 38 33 34
438 446 454 462 470
57 ~9 S# 46 44
439 447 455 463 471
32 28 27 26 23
440 448 456 464 472
61 53 SO 47 36
441 449 #57 465 473
30 30 26 26 21
#47 #50 458 #&6 474
58 54 41 45 38
4#3 451 #59 467 475
30 30 23 25 22
44# 452 460 468 476
47 52 64 48 40
445 453 461 469 477
27 28 25 24 22
478 486 494 502 510
41 31 34 28 30
479 487 495 503 511
23 17 lfl 15 1~
480 4AR 496 504 512
40 33 35 30 78
#81 #89 497 505 513
22 19 18 17 18
#82 #90 498 506 514
40 35 33 30 27
483 49] 490 507 515
21 19 17 18 13
484 492 500 508 516
38 35 26 29 24
485 493 SOl 509 517
20 F0 15 17 14
518 526 534 542 550
25 24 ~1 1S 16
519 527 535 543 551
14 13 12 9 9
520 528 536 544 552
26 18 20 16 16
521 529 537 ~45 553
1# II 1] 11 9
5~2 530 538 546 554
24 20 20 18 14
523 53] 539 547 55~
14 12 II I0 8
524 532 S#o 548 5~6
24 20 18 18 II
525 533 541 549 557
14 12 II 10 7
558
566 5 7# 582 590
11 12 I0 8 8
559 567 575 583 591
R O 6 S 6
~60 568 576 584 K92
13 11 lO 7 8
561 569 577 585 593
8 8 6 ~ #
562 570 578 586 ~94
14 9 9 7 7
563 571 570 587 59~
8 6 6 S 4
564 572 580 5~ 596
12 10 9 7 6
565 573 581 ~89 597
a 8
5 98 6 06 614 622
5 5 4 4
599 607 615 624
4 3 4 3
600 &08 616 626
6 5 4 3
601 609 617 628
# 3 3 3
602 610 618 630
8 4 4 3
603 61] 619 632
4 604 3 612 3 620 3099999
6 4 4
605 613 621
525
5 4 .
3 3
o a2a9 l 1.1.2 Reproducibility--The difference between two single and independent results, obtained by different operators working in different laboratories on identical test material, would in the long run, in the normal and correct operation of the test method, exceed the values shown in Table 5 only in one case in twenty.
conditions employed in this empirical method, and a statement of bias is therefore not appropriate. 12. Keywords
12. l aromatic; gas off; mass spectrometry; petroleum
NOTE 6--1f samples are analyzed that differ appreciably in composition from the sample used for the interlaboratory study, this precision statement may not apply.
TABLE 5
11.2 Bias--The quantities determined are defined by the TABLE 4 M a s s Spectral A n a l y s i s o f A r o m a t i c Fractions PC-69-378 Test Spectrum for Gas Oil Aromatics Analysis Calc. Ion Sums Volume %
90.
Monoaromatics: Alkylbenzenes Naphthenebenzenes Dinaphthenebenzenes Diaromatics: Naphthalenes Acenaphthenes. dibenzofurans Fluorenes Triaromatics: Phenanthrenes Naphthenephenanthrenes Tetraaromatics: Pyrenes Chrysenes Pentaaromatics: Perylenes Dibenzanthracenes ThiophenoAromatics: Benzothiophenes Dibenzothiophenes Naphthobenzothiophenes Unidentified Aromatics: Class I incl with Naphthenephenanthrenes Class II Class III Class IV Class V Class VI Class VII
28498. 9703. 9017. 9778. 19158.
26.2
4774. 6576.
6.5 9.0
7809.
10.7 9625.
6070.
8.3 5.4 2.9
1658. 1293. 366
2.3 1.8 05
1872. 565. 988. 339.
2.6 0.8 1.3 0.5
6322.
614. 838. 3431. 546. 281. 612.
¢rr
oR
r
R
13.7 13.3 13.7
0.3 0.1 0.2
1.0 1.1 0.4
1.2 0.5 0.9
3.0 3.3 1.1
Naphthalenes Acenaphthenes/dibenzofurans Fluorens
6.7 9.0 10.7
0.2 0.1 0.1
0.8 0.2 0.2
0.9 0.5 0.3
2.3 0.5 0.6
Phenanthrenes Naphthenephenanthrenes
8.6 4.5
0.1 0.2
0.3 0.4
0.2 0.7
1.0 1.2
Pyrenes Chrysenes
5.7 2.8
0.1 0.2
0.5 0.4
0.3 0.5
1.6 1.1
Perylenes Dibenzanthracenes
1.7 0.4
0.1 0.1
0.2 0.1
0.3 0.2
0.6 0.4
Benzothiophenes Dibenzothiophenes Naphthabenzothiophenas
1.0 1.5 0.5
0.2 0.1 0.1
0.4 0.3 0.3
0.8 0.3 0.3
1.1 0.8 1.0
Class II Unidentified Class III Unidentified Class IV Unidentified Class V Unidentified Class VI Unidentified Class VII Unidentified
0.4 0.6 4.1 0.5 0.2 0.4
0.1 0.1 0.2 0.1 0.1 0.2
0.4 0.4 0.5 0.3 0.1 0.2
0.3 0.4 0.6 0.5 0.3 0.5
1.1 1.2 1.6 0.8 0.4 0.7
13.1 8.4 4.7
3980. 2090.
Vol ~ Alkylbenzenes Naphthenebenzenes Dinaphthenebenzenes
38.9 13.3 12.3 13.4
6156. 3470.
Precision Summary Based on Cooperative Data
~, = repeatability standard deviation ~ = reproduobility standard deviation r = repeatability R = reproducibility
8.6
0.8 1.1 4.7 0.7 0.4 0.8
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards. 1916 Race St., Philadelphia, PA 19103.
526
(~t)
Designation: D 3241 - 97
..
Designation: 323/89
i,~.ur,
An Amedean National Standard
Ilk m i aiH [[IM
Standard Test Method for Thermal Oxidation Stability of Aviation Turbine Fuels (JFTOT Procedure) 1 This standard is issued under the fixed designation D 3241; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epeflon (0 indicates an editorial change since the last revision or reapproval.
This test method has been approved by the sponsoring committee and accepted by the cooperating organizations in accordance with established procedures. This standard has been approved for use by agencies of the Department of Defense. Consult the DoD Index of Specifications and Standards for the specific year of issue which has been adopted by the Department of Defense.
Color Standard for Tube Deposit Rating5
1. Scope 1.1 This test method covers the procedure for rating the tendencies of gas turbine fuels to deposit decomposition products within the fuel system. 1.2 The values stated in SI units are to be regarded as the standard. The inch-pound values given in parentheses are for information only. The differential pressure values in mm Hg are defined only in terms of this test method.
1.3 This standard does not purport to address all of the safety concerns, if any,, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Notes 1, 2, 3, 7 and Annex A2.
3. Terminology 3.1 Definitions of Terms Specific to This Standard: 3.1.1 deposits--oxidative products laid down on the test area of the heater tube or caught in the test filter, or both. 3.1.1.1 DiscussionDFuel deposits will tend to predominate at the hottest portion of the heater tube which is between the 30 mm and 50 mm position. 3.1.2 heater tubeDan aluminum coupon controlled at elevated temperature, over which the test fuel is pumped. 3.1.2.1 Discussion--The tube is resistively heated and controlled in temperature by a thermocouple positioned inside. The critical test area is the thinner portion, 60 mm in length, between the shoulders of the tube. Fuel inlet to the tube is at the 0 mm position, and fuel exit is at 60 mm. 3.2 Abbreviation: 3.2.1 AP--differential pressure.
2. Referenced Documents
4. Summary of Test Method 4.1 This test method for measuring the high temperature stability of gas turbine fuels uses the Jet Fuel Thermal Oxidation Tester OF'rOT) that subjects the test fuel to conditions that can be related to those occurring in gas turbine engine fuel systems. The fuel is pumped at a fixed volumetric flow rate through a heater after which it enters a precision stainless steel filter where fuel degradation products may become trapped. 4.1.1 The apparatus uses 450 mL of test fuel ideally during a 2.5 h test. The essential data derived are the amount of deposits on an aluminum heater tube, and the rate of plugging of a 17 Ix nominal porosity precision filter located just downstream of the heater tube.
2.1 A S T M Standards: D 1655 Specification for Aviation Turbine Fuels: D 4306 Practice for Aviation Fuel Sample Containers for Tests Affected by Trace Contaminationa E 128 Test Method for Maximum Pore Diameter and Permeability of Rigid Porous Filters for Laboratory Use4 E 177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods4 E 691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test MethOd4 2.2 Adjunct:
5. Significance and Use 5.1 The test results are indicative of fuel performance during gas turbine operation and can be used to assess the level of deposits that form when liquid fuel contacts a heated surface that is at a specified temperature.
' This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.J on Aviation Fuels. Current edition approved June 10, 1997. Published October 1997. Originally published as D 3241 - 73 T. Last previous edition D 3241 - 96a. 2 Annual Book of ASTM Standards, Vo105.01. 3 Annual Book of ASTM Standards, Vo105.02. 4 Annual Book of ASTM Standards, Vol 14.02.
s Available from ASTM Headquarters. Order Adjunct No. 12-416600-00.
527
(@) D 3241 TABLE 1 JFTOT Model
User Manual
Models of JFTOT
Pressurize Pump With Principle Differential PreSsUreBy
202
202/203A
nitrogen
gear
203
202/203 A
nitrogen
gear
215
215 s
nitrogen
gear
230 240
230/240 ¢ 230/240 c
hydraulic hydraulic
syringe syringe
Hg Manometer; No Record Manometer + Graphical Record Transducer + Printed Record Transducer + Printout Transducer + Printout
TABLE 2
Cdtical Operating Charactadstics of JFTOT Instruments Item
Definition tubeqn-shell heat exchanger as illustrated in Fig. 1.
Test apparatus Test coupons Heater tube•
speciallyfabricated aluminum tube that produces controlled heated test surface; new one for each test nominal 17 ttm stainless steel mesh filter element to trap deposits; new one for each test
Test filtere Instrument parameters Sample volume
'q AvalleUtefrom ASTM Headquarters. Request RR:O02-1395. • Available from ASTM Headquarters. Request RR:D02-1396. c Available from ASTM Headquarters. Request RR:D02-1397.
Aeration rate Flow dudng test Pump mechanism Cooling
6. Apparatus 6.1 Jet Fuel Thermal Oxidation Tester~ (JFTOT)--Five models of suitable equipment may be used as indicated in Table 1. 6.1.1 Portions of this test may be automated. Refer to the appropriate user manual for the model JFTOT to be used for a description of detailed procedure. A manual is provided with each test rig, and the latest version of each manual is on file at ASTM as a Research Report. 6 See Table 1.
Thermocoupie (TC) Operating pressure System At test filter
Operating temperature For test Uniformity of run
N O ~ 1: Caution~No attempt should be made to operate the JFTOT without firstbecoming acquainted with all components and the function of each.
Calibration
6.1.2 Certain operational parameters used with the JFTOT instrument are critically important to achieve consistent and correct results. These are listed in Table 2., 6.2 Heater Tube DepOsit Rating Apparatus: 6.2.1 Visual Tube Rater, the tuberator described in'Annex AI.
600 mL of sample is aerated, then this aerated fuel is used to flU the reservoir leaving space for the piston; 450 ± 45 mL may be pumped In a valid test 1.5 L/rain dry air through sparger 3.0 ± 10 % mL/min (2.7 rain to 3.3 max) positive displacement, gear or piston s~nge bus bars fluid cooled to maintain consistent tube temperature profile Type J, fibre braid or Iconel sheathed 3.45 MPa ± 10 % on sample by pressurized inert gas (nitrogen) or by hydraulicallytransmitted force against control valve outlet restriction differential pressure (Ap) measured across test filter (by mercury manometer or by electronic trensducer) in mm Hg as stated in specification for fuel maximum deviation of ±2oC from specified temperature pore tin at 232"C (and for Models 230 and 240 only, pure lead at 327"C for high point and ice + water for low point reference)
NoTe 4: Warning--Do not inhale dust or ingest. May cause stomach disorder.
8. Standard Operating Conditions 8.1 Standard conditions of the test method are as follows: 8.1.1 Fuel Quantity, 450-mL minimum for test + about 50 mL for system. 8.1.2 Fuel Pre-treatment--Filtration through a single layer of general purpose, retentive, qualitative filter paper followed by a 6-rain aeration at 1.5 L/min air flow rate for a maximum of 600 mL sample using sparge stone of porosity C (see Test Method E 128). 8.1.3 Fuel System Pressure, 3.45 MPa (500 psi) _10 % gage. 8.1.4 Thermocouple Position, at 39 ram. 8.1.5 Fuel System Prefilter Element, filter paper of 0.45 ttm pore size.
7. Reagents and Materials 7.1 Use distilled (preferred) or deionized water in the spent sample reservoir as required for Model 230 and 240 JFTOTs. 7.2 Use methyl pentane, 2,2,4 trimethylpentane or nheptane (technical grade, 95 reel % minimum purity) as general cleaning solvent. This solvent will effectively clean internal metal surfaces of apparatus before a test, especially those surfaces (before the test section) that contact fresh sample. NOTe 2: Warning--Extremely flammable. Harmful if inhaled (see Annex A3).
7.2.1 Use trisolvent (equal mix of acetone (1), toluene, (2) isopropanol (3)) as a specific solvent to clean internal (working) surface of test section only.
CooI~ Bus Ba~
NffrE 3: Warning---(/) Extremely flammable, vapors may cause flash fire;(2) and (3) Flammable.Vapors of all three harmful.Irritating to skin, eyes and mucous membranes.
7.3 Use dry calcium sulfate + cobalt chloride granules (97 + 3 mix) in the aeration dryer. This granular material changes gradually from blue to pink color indicating absorption of water. e Originally supplied with apparatus and available from ALCOR Petroleum Instruments, Inc., Box 792222, San Antonio, TX 78279-2222. Now availablefrom ASTM as a research report. See Table 1.
FIG. 1
528
Standard Heater Section, Essential to All JFTOT Instruments
~
V
3241
8.1.6 Heater Tube Control Temperature, preset as specified in applicable specification. 8.1.7 Fuel Flow Rate, 2.7 to 3.3 mL/min, or 20 drops of fuel in 9.0 -t- 1.0 s. 8.1.8 Minimum Fuel Pumped During Test, 405 mL. 8.1.9 Test Duration, 150 ± 2 rain. 8.1.10 Cooling Fluid Flow, approximately 39 L/h, or center of green range on cooling fluid meter. 8 . l . l l Power Setting, approximately 75 to 100 on noncomputer models; internally set for computer models.
10.1.2 Differential Pressure Cell--StandarcYtze once a year or when installing a new cell (see Annex A2.2.6). 10.1.3 Aeration Dryer--Check at least monthly and change if color indicates significant absorption of water (see 7.3). 10.1.4 Metering Pump---Perform two checks of flow rate for each test as described in the Procedure section. 10.1.5 Filter Bypass Valve--For Models 202, 203, and 215--check for leakage at least once a year (see Appendix X5).
9. Preparation of Apparatus
11. Procedure
9.1 Cleaning and Assembly of Heater Test Section: 9.1.1 Clean the inside surface of the heater test section using a nylon brush saturated with trisolvent material to remove all deposits. 9.1.2 Check the heater tube to be used in the test for surface defects and straightness by referring to the procedure in Annex AI.10. Be careful, also, to avoid scratching tube shoulder during the examination since the tube shoulder must be smooth to ensure a seal under the flow conditions of the test. 9.1.3 Assemble the heater section using new items: (1) visually checked heater tube, (2) test filter and (3) three O-rings. Inspect insulators to be sure they are undamaged. NOTE 5--Heater tubes must not be reused. Tests indicate that magnesium migrates to the heater tube surface under normal test conditions. Surface magnesium may reduce adhesion of deposits to reused heater tube. 9.1.4 During assembly of heater section, handle tube carefully so as not to touch center part of tube. IF CENTER OF HEATER TUBE IS TOUCHED, REJECT T H E TUBE SINCE THE CONTAMINATED SURFACE MAY AFFECT THE DEPOSIT FORMING CHARACTERISTICS OF T H E TUBE. 9.2 Cleaning and Assembly of Remainder of Test Compo-
nents:
11.1 Preparation of Fuel Test Sample: 11.1.1 Filter and aerate sample using standard operating conditions (see Annex A2.2.8). NOTE 7--Before operating see Caution under Note 1. NOTE 8--Test method results are known to be sensitive to trace contamination from sampling containers. For recommended containers, refer to Practice D 4306. NOTE 9: Wm~aing--All jet fuels must be considered flammable except JP5 and JP7. Vapors are harmful (see Annex A3.3, A3.6, and A3.7). 11.1.2 Maintain temperature of sample between 15"C and 32"C during aeration. Put reservoir containing sample into hot or cold water bath to change temperature, if necessary. 11.1.3 Allow no more than 1 h to elapse between the end of aeration and the start of the heating of the sample.
11.2 Final Assembly: 11.2.1 Assemble the reservoir section (see User Manual). 11.2.2 Install reservoir and connect lines appropriate to the model JFTOT being used (see User Manual). 11.2.3 Remove protective cap and connect fuel outlet line to heater section. Do this quickly to minimize loss of fuel. 11.2.4 Check all lines to ensure tightness. 11.2.5 Recheck thermocouple position at 39 ram. 11.2.6 Make sure drip receiver is empty (Models 230 and 240 only).
11.3 Power Up and Pressurization:
9.2.1 Perform the following steps in the order shown prior to running a subsequent test. NOTE 6ult is assumed apparatus has been disassembled from previous test (see Annex A2 or appropriate user manual for assembly/ disassembly details). 9.2.2 Inspect and clean components that contact test sample and replace any seals that are faulty or suspect especially the: (1) lip seal on piston, and (2) O-rings on the reservoir cover, lines, and prefilter cover. 9.2.3 Install prepared heater section (as described in 9.1.1 through 9.1.4). 9.2.4 Assemble pre-filter with new element and install. 9.2.5 Check thermocouple for correct reference position, then lower into standard operating position. 9.2.6 On Models 230 and 240 make sure the water beaker is empty.
11.3.1 Turn POWER to ON. 11.3.2 Energize the AP alarms on models with manual alarm switch (Models 202, 203, and 215). 11.3.3 Pressurize the system slowly to about 3.45 MPa as directed in the User Manuals for Models 202, 203, and 215 (see also Annex A2.2.5). 11.3.4 Inspect the system for leaks. Depressurize the system as necessary to tighten any leaking fittings. 11.3.5 Set controls to the standard operating conditions. 11.3.6 Use a heater tube control temperature as specified for the fuel being tested. Apply any thermocouple correction from the most recent calibration (see Annex A2.2.7). NOTE 10--The JFTOT can be run to a maximum tube temperature of about 350"C. The temperature at which the test should be run, and the criteria for judging results are normally embodied in fuel specifications.
11.4 Start Up:
10. Calibration and Standardization Procedure 10.1 Perform checks of key components at the frequency indicated in the following (see Annexes or user manual for details). 10.1.1 Thermocouple--Calibrate a thermocouple when first installed and then normally every 30 to 50 tests thereafter, but at least every 6 months (see Annex A2.2.8).
11.4.1 Use procedure for each model as described in the appropriate User Manual. 11.4.2 Some J F T O T models may do the following steps automatically, but verify that: 11.4.2.1 No more than 1 h maximum elapses from aeration to start of heating. 11.4.2.2 The manometer bypass valve is closed as soon as 529
~
D 3241 11.8.3.2 Discard fuel to waste disposal.
the heater tube temperature reaches the test level, so fuel flows through the test filter (see Annex A2.2.6). 11.4.2.3 Manometer is set to zero (see Annex A2.2.6). 11.4.3 Check fuel flow rate against Standard Operating Conditions by timing flow or counting the drip rate during first 15 rain of test.
12. Heater Tube Evaluation 12.1 Visually rate the deposits on heater tube in accordance with Annex A 1. 12.2 Return tube to original container, record data, and retain tube for visual record as appropriate.
NOTE I l--When counting drop rate,the firstdrop is counted as drop 0, and time is started.As drop 20 falls,total time is noted.
11.5 Test: 11.5.1 Record filter pressure drop every 30 rain minimum during the test period. 11.5.2 If the filter pressure drop begins to rise sharply and it is desired to run a full 150 rain test, a bypass valve common to all models must be opened in order to finish the test. See appropriate User Manual for details on operation of the bypass system (see Annex A2.2.2). 11.5.3 Make another flow check within final 15 rain before shutdown (see 11.4.3 and accompanying note). 11.6 Heater Tube Profile--lf a heater tube temperature profile is desired, obtain as described in Appendix X4. 11.7 Shutdown: 11.7.1 For Models 202, 203, and 215 only: 11.7.1.1 Switch HEATER, then PUMP to OFF. 11.7.1.2 Close NITROGEN PRESSURE VALVE and open MANUAL BYPASS VALVE. 11.7.1.3 Open NITROGEN BLEED VALVE slowly, if used, to allow system pressure to decrease at an approximate rate of 0.15 MPa/s. 11.7.2 Models 230 and 240 shut down automatically. 11.7.2.1 After shutdown, turn FLOW SELECTOR VALVE to VENT to relieve pressure. 11.7.2.2 Piston actuator will retreat automatically. 11.7.2.3 Measure effluent in drip receiver, then empty. 11.8 Disassembly: 11.8.1 Disconnect fuel inlet line to the heater section and cap to prevent fuel leakage from reservoir. 11.8.2 Disconnect heater section. 11.8.2.1 Remove heater tube from heater section carefully so as to avoid touching center part of tube, and discard test filter. 11.8.2.2 Flush tube with solvent material from top down while grasping tube at bottom and holding vertically. Allow to dry, return tube to original container, mark with identification and hold for evaluation. 11.8.3 Disconnect reservoir. 11.8.3.1 Measure the amount of spent fluid pumped during the test, and reject the test if the amount is less than 405 mL.
13. Report 13.1 Report the following: 13.1.1 The heater tube control temperature. This is the test temperature of the fuel. 13.1.2 Heater tube deposit rating(s). 13.1.3 Maximum pressure drop across the filter during the test or the time required to reach a pressure differential of 25 ram Hg. For the Model 202, 203 JFTOT, report the maximum recorded AP found during the test. 13.1.4 If the normal 150 rain test time was not completed, for example, if the test is terminated because of pressure drop failure, also report the test time that corresponds to this heater tube deposit rating. Nox~ 12--Eitherthe tube rating or the AP criteria, or both, are used to determinewhethera fuel samplepasses or failsthe test at a specified test temperature. 13.1.5 Spent fuel at the end of a normal test. This will be the amount on top of floating piston or total fluid in displaced water beaker, depending on model of JVrOT used.
14. Precision and Bias 14.1 An interlaboratory study of JFTOT testing was conducted in accordance with Practice E 691 by eleven laboratories, using thirteen instruments including two JFTOT models with five fuels at two temperatures for a total of ten materials. Each laboratory obtained two results from each material. See ASTM Research Report No. D02:1309. 14.1.1 The terms repeatability and reproducibility in this section are used as specified in Practice E 177. 14.2 Precision--The precision of this procedure for determining the thermal oxidative stability of aviation turbine fuels is being determined. 14.3 Bias--This test method has no bias because jet fuel thermal oxidative stability is defined only in terms of this test method. 15. Keywords 15.1 differential pressure; fuel decomposition; oxidative deposits; test filter deposits; thermal stability; turbine fuel
ANNEXES
(Mandatory Information) A1. TEST METHOD FOR VISUAL RATING OF JZI'OT HEATER TUBES
AI.I Scope A 1.1.1 This method covers a procedure for visually rating the heater tube produced by Test Method D 3241, JVrOT Procedure.
AI.1.2 The final result from this test method is a tube color rating based on an arbitrary scale established for this test method plus two additional yes/no criteria that indicate
530
(~ D 3241 the presence of an apparent large excess of deposit or an unusual deposit, or both.
AI.8.5 Evaluators--Use persons who can judge colors, that is, they should not be color blind.
A1.2 Referenced Documents AI.2.1 Adjunct: Color Standard for Tube Deposit Rating5
A1.9 Calibration and Standardization Procedure AI.9.1 No standardization is required for this test apparatus, but since the Color Standard is known to fade, store it in a dark place. NOTE AI.2--The lifetimeof the Color Standard is not establ/shed when continuouslyor intermittentlyexposedto fight.It is goodpractice to keep a separate Standard in dark (no fight) storage for periodic comparison with the Standard in regular use. When comparing, the optimum under the light conditionsare those of the tube rating box. A 1.9.2 Standardization of Rating Technique: AI.9.2.1 In rating a tube, the darkest deposits are most important. Estimate grades for the darkest uniform deposit, not for the overall average color of the deposit area. A 1.9.2.2 When grading, consider only the darkest continuous color that covers an area equal or larger than a circle of size one-half the diameter of the tube. AI.9.2.3 Ignore a deposit streak that is less in width than one-quarter the diameter of the tube regardless of the length of the streak. A 1.9.2.4 Ignore spots, streaks, or scratches on a tube that are considered tube defects. These will normally not be present since the tube is examined before use to eliminate defective tubes.
A1.3 Terminology AI.3.1 abnormalma tube deposit color that is neither peacock nor like those of the Color Standard. A 1.3.1.1 Discussion--This refers to deposit colors such as blues and grays that do not match the Color Standard. A 1.3.2 peacockmA multicolor, rainbow-like tubedeposit. AI.3.2.1 Discussion--This type of deposit is caused by interference phenomena where deposit thickness exceeds the quarter wave length of visible light. AI.3.3 Tube Rating--A ten step discrete scale from 0 to >4 with intermediate levels for each number starting with 1 described as less than the subsequent number. A1.3.3.1 Discussion--The scale is taken from the five colorsm0, 1, 2, 3, 4--on the ASTM Color Standard. The complete scale is: 0, 1.5 1.7-9 >9
0.03(X) + 0.01 0.03 0.03(X) + 0.02 0.62
15 16 15 16
TABLE 2 Reproducibility NOTE--X ffi the mean volume Y, of the component.
557
Component
Range, volume ~
Repeatability
See Note
Benzene Benzene Toluene Toluene
0.1-1.5 >1.5 1.7-9 >9
0.13(X) + 0.05 0.28(X) 0.12(X) + 0.07 1.15
15 16 15 16
o 3so6 15.2 BiasmSince there is no accepted reference method suitable for measuring bias for this method, no statement of bias can be made.
16. Keywords 16.1 aviation gasoline; benzene; gas chromatography; gas. oline; toluene
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any Item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard Is subject to revision at any time by the responsible technical committee and must be reviewed every five years and ff not revised, either reepproved or withdrawn. Your comments are Invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohocken, PA 19428.
558
(~)
Designation: D 3700 - 94
An American National Standard
Standard Practice for Containing Hydrocarbon Fluid Samples Using a Floating Piston Cylinder I This standard is issued under the fixed designation D 3700; the number immediately following the designation indicates the year of original adoption or, in the case &revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsiion (0 indicates an editorial change since the last revision or re,approval.
laboratory test, can be useless if the samples are not valid.
1. Scope 1.1 This practice describes equipment and a procedure for obtaining a representative sample of a homogeneous hydrocarbon fluid and the subsequent preparation of that sample for laboratory analysis. 1.2 It is not possible, nor is it the intent of this practice, to provide a procedure that will be applicable for all sampling situations. It is strongly recommended that the samples be obtained under the supervision of a person knowledgeable in the phase behavior of hydrocarbon systems and experienced in all sampling operations. 1.3 This practice does not include recommendations for the location of the sampling point in a line or vessel, although the importance of the proper sampling location cannot be over-emphasized. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.For specific hazard statements, see 4. I and Annex A2.
4. Hazards 4.1 Safety Precautions: 4.1.1 WarningDSampling hydrocarbon fluids can be hazardous. Persons responsible for obtaining samples should be familiar with and adhere to safe practices for handling flammable fluid under pressure. 4.1.2 Disassembly of the piston cylinder for maintenance presents a special hazard. Should either end cap be removed while pressure is on the cylinder, the end caps and the piston can be ejected with such force as to cause serious injury to personnel and damage to adjacent equipment. The following steps are recommended for disassembly: 4.1.2.1 PrecautionnClamp the piston cylinder firmly to a steady work surface. 4.1.2.2 Vent both ends of the cylinder to atmospheric pressure before attempting to remove either end cap. 4.1.2.3 Clear the area at either end of the cylinder before loosening the end plug. 4.1.2.4 Provide a mechanical plunger to dislodge the piston from the cylinders. Do not use fluid pressure. 4.2 Technical Precautions: 4.2.1 A certain amount of information about a sample is necessary before it can be intelligently handled in the laboratory. Absolutely essential are the sample source, sample date, cylinder identification, sample pressure and temperature, ambient temperature, type of analysis required, and the sampling method used. There can be additional related facts such as field-determined results and operating conditions which will assist in the evaluation of the analytical data. This information should accompany the filled sample cylinder. 4.2.2 If the hydrocarbon fluid samples are to be transported by common carrier within the United States, the sample containers must meet the specifications and be labeled according to the Hazardous Materials Regulations of the Department of Transportation. 4.2.3 Containers must be thoroughly cleaned prior to sampling with an appropriate volatile solvent, for example, petroleum naphtha followed by acetone, and evacuated to remove traces of the solvent. The use of detergent/water solutions or steam is not recommended.
2. Summary of Practice 2.1 A hydrocarbon fluid sample is transferred under pressure from a source to a moving piston cylinder. The piston-type cylinder is designed to collect fluid samples by displacing a pressurizing fluid (usually an inert gas) at sampling pressure. The piston serves as a barrier between the sample and the inert gas which maintains the integrity of the sample by preventing the selective absorption of sample components in the pressurizing fluid as is possible in conventional displacement techniques. The method provides for a 20 % inert gas volume for safe storage and transport of the sample. 3. Significance and Use 3.1 The objective of any sampling operation is to secure, in a suitable container, an adequate portion of hydrocarbon fluid under pressure having the same composition as the stream being sampled. 3.2 Particular emphasis should be given to the necessity of obtaining accurate, representative samples for analysis since those analyses, regardless of the care and accuracy of the
5. Apparatus 5.1 Container, shown in Fig. 1 as Cylinder X, constructed of metal tubing, honed, and polished on the inside surface. The cylinder is closed with threaded end caps to provide access to remove and service the moving piston. The end caps are drilled and tapped for valves. The cylinder is
' This practice is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.H on Liquefied Petroleum Gases. Current edition approved July 15, 1994. Published September 1994. Originally published as D 3700 - 78. Last previous edition D 3700 - 78 (1988)~t
559
(I ~ D 3 7 0 0 designed to exceed the maximum pressure anticipated during sampling and to be resistant to materials being sampled, the pressurizing fluid, the cleaning solvents, and the expected corrodents. The volume of the cylinder will depend on the amount of sample needed for the laboratory analysis. 5.1.1 The cylinder contains a moving piston. The piston is equipped with O-rings, TFE-fluorocarbon rings, or other devices to affect a leak-free seal between the sample and the
Sample • source .
A
pressurizingfluid,and to allow for the freemovement of the piston within the cylinder.The use of guide rings is recommended to ensure smooth piston travel. The piston and scaling device must be resistantto the sample, the pressurizing fluid,the cleaning solvents,and expected corrodents. 5.1.2 All valves and safety devices must meet the appropriate material and pressure specifications. 5.2 Displacement Container--This container, Fig. I, Cylinder Y, shallbe fabricatedfrom metal tubing, be designed to meet the same pressure requirements as the piston cylinder, and have a volume of no more than 80 % of the pressurizing volume of the piston cylinder (80 % of piston cylinder volume minus the volume of the piston). 5.3 Transfer Lines, Valves, and Gages--The transfer system shall be designed to exceed the maximum anticipated pressure and be resistant to all expected corrodents. The transfer lines should have a minimum diameter of 6.35 mm (V4 in.) and be as short as is practical, see Fig. 1. The use of filters and dryers is discouraged.
MI
6. J_aboratory Preparation 6.1 The following procedure is recommended for liquidphase samples: 6.I.l Check the sample pressure on inert gas end, Valve D. The sample pressure should equal the sample source pressure corrected for the laboratoryambient temperature. 6.1.2 Connect the external pressure source of inert gas to Valve D and adjust the sample pressure equal to the saturation pressure of the sample at the laboratoryambient temperature plus a minimum of 1380 kPa (200 psi). 6.1.3 Rock the sample cylinderto ensure that the sample is homogeneous. 6.1.4 Place the cylinder in a horizontal position. The sample is now ready to transfer for analysis. The pressure described in 6.1.2 must be maintained on the sample during the transferoperation. 6.1.5 For use with gaseous phase samples, referto Annex Al.
Sample Floating piston Inert gas
Cylinder ,,X,J
7. Sampling Procedure
7.1 Use the displacement cylinder technique for the liquid phase samples. 7.1.1 With the sample side of the piston cylinder evacuated (from cleaning operation) and Valve C closed, fill the displacement end with an inert gas to approximately (68.9 kPa) (10 psi) above the sampling pressure. Close Valve D. 7.1.2 Connect piston Cylinder X to sample Source A and displacement Cylinder Y to piston cylinder as shown in Fig. 1. Fill the displacement cylinder with air at atmosphere pressure. 7.1.3 With Valves B and C closed, open sample source Valve A to full open position. Observe the sample source pressure on Gage M. Crack Valve B and fitting to Valve C to purge line. Do not allow Pressure M to drop below sample pressure. Tighten fitting to Valve C and close Valve B. 7.1.4 With Valve E closed, open Valve D and observe pressure on Gage N. Adjust pressure N to equal pressure M by slowly venting inert gas through Valve E. Close Valve E. 7.1.5 With Valve E closed, slowly open Valve C to full open. There should be no pressure drop indicated on Gage N. 7.1.6 Close Valve D. Open Valve E and vent pressure at
Cylinder ,,y,,
Figure I
Sampling system for hydrocarbon fluids (Not)o scale)
FIG. 1 Sampling System for Hydrocarbon Fluids 560
q~) D 3700 Disconnect displacement cylinder. Disconnect piston cylinder from sample source. 7.1.9 Do not take outage or reduce pressure on piston cylinder. Check Valves C and D for leaks, plug valves to protect threads, prepare sample information tag, and box for transport.
atmosphere through Valve F. Close Valve F. 7.1.7 Slowly open Valve D allowing inert gas to flow into Cylinder Y. Observe Gage M so as not to allow pressure M to drop. Continue operation until pressure N equals pressure M. At this point, a volume equal to Cylinder Y has been displaced from Cylinder X by the hydrocarbon fluid sample. Sample Cylinder X now contains 80 volume % of sample leaving sufficient inert gas space to ensure safe storage and transport. 7.1.8 Close Valves D, C, and A. Open Valves B and F.
8. Keywords 8.1 floating piston cylinder; hydrocarbon fluid sampling; LP-gas; sampling
ANNEXES
(Mandatory Information) A1. GAS-PHASE SAMPLING AI.I The piston cylinder method is believed to be applicable for both liquid-phase and gaseous-phase samples. However, while the technique has been successfully used for liquid samples, there is no experience obtaining gas-phase samples. AI.2 The technique for obtaining gas-phase samples would be identical to the procedure described in Section 7. A1.3 The technique for the laboratory preparation of a gas phase sample is somewhat different from that described in Section 6. The following procedure is recommended for the laboratory preparation of gas-phase samples: AI.3.1 Check sample pressure on inert gas end, Valve D. The sample pressure should equal the sample source pressure corrected for laboratory ambient temperature. A1.3.2 Heat the sample cylinder for a minimum of I h at the hydrocarbon dew point (if known) or the sample source temperature, plus I l+*C (20*F). AI.3.3 If the gas sample is known to be "dry" (does not form condensation on cooling by expansion), the sample is now ready to transfer for analysis. If the sample is known to be "wet" (partially condenses upon cooling or by a variation in pressure), the sample pressure must be maintained on piston cylinder during transfer by adding inert gas, Valve D, from external pressure source. All gases of unknown composition or exceeding 345 kPa (500 psi) sample source pressure should be treated as "wet" gases. A.1.3.4 The transfer line from the sample cylinder to analytical instrument should be heat-traced. A I.4 Some piston-type cylinders are fabricated from nonmagnetic materials such as the 300 series of stainless
steels and the piston from magnetic carbon steel. With this type of cylinder construction, the progress of the piston movement during sample entry can be followed by placing a small magnet on the outside surface of the cylinder. This technique eliminates the need for the displacement container and simplifies the sampling procedure. The following procedure is recommended: A 1.4.1 With the sample side of piston cylinder evacuated from the cleaning operation and Valve C closed, fill the displacement end, Valve D, with inert gas to sampling pressure. Close Valve D. A 1.4.2 With Valves B and C closed, open sample source Valve A to full open position. Observe sample source pressure on Gage M. Crack fitting to Valve C and purge line. Do not allow Pressure M to drop below sample pressure. Tighten the fitting. AI.4.3 Check pressure of inert gas side, Valve D, and adjust to equal Pressure M. AI.4.4 Slowly open Valve C to full open. There should be no pressure drop at Gage N. AI.4.5 Crack Valve D allowing inert gas to purge to atmosphere. Do not allow Pressure M to drop below sampling pressure. Continue purge until the piston has moved 80 % of the length of the cylinder as indicated by the magnet locator. Close Valves D, C, and A. Open B and disconnect piston cylinder from sample source. AI.4.6 Do not take outage or reduce pressure on piston cylinder. Check Valves C and D for leaks, plug valves to protect threads, prepare sample information tag, and box for transport.
561
~
D 3700
A2. PRECAUTIONARY STATEMENTS A2.1.5 Avoid buildup of vapors and eliminate all sources of ignition, especially nonexplosive electrical devices and heaters. A2.1.6 Avoid prolonged breathing of vapor or spray mist. A2.1.7 Avoid prolonged or repeated skin contact.
A2.1 Flammable Liquefied Gases
A2.1.1 A2.1.2 A2.1.3 A2.1.4
Vapors may cause flash fires. Keep away from heat, sparks, and open flame. Keep container closed. Use with adequate ventilation.
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are Invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical cornm/ttea, which you may attend, ff you feel that your comments have not received • fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, Pit 19103.
562
@ @
Designation: D 3701 - 92
An American National Standard
Designation:337/85(90) Standard Test Method for Hydrogen Content of Aviation Turbine Fuels by Low Resolution Nuclear Magnetic Resonance Spectrometry 1 This standard is issued under the fixed designation D 3701; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 This test method covers the determination of the hydrogen content of aviation turbine fuels. 1.2 Use Test Method D 4808 for the determination of hydrogen in other petroleum liquids. 1.3 The preferred units are mass percent hydrogen. 1.4 This standard does not purport to address all of the
safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For a specific precautionary statement, see Note I.
2. Referenced Documents
2.1 A S T M Standards: D4057 Practice for Manual Sampling of Petroleum and Petroleum Products2 D4808 Test Method for Hydrogen Content of Light Distillates, Middle Distillates, Gas Oils, and Residua by Low-Resolution Nuclear Magnetic Resonance Spectroscopy2
3. Summary of Test Method 3.1 A sample of the material is compared in a continuous wave, low-resolution, nuclear magnetic resonance spectrometer with a reference standard sample of a pure hydrocarbon. The results from the integrator on the instrument are used as a means of comparing the theoretically hydrogen content of the standard with that of the sample, the result being expressed as the hydrogen content (percent weight basis) in the sample. 4. Significance and Use 4. I The combustion quality of aviation turbine fuel has traditionally been controlled in specifications by such tests as smoke point, smoke volatility index, aromatic content of luminometer number. Evidence is accumulating that a better control of the quality may be obtained by limiting the minimum hydrogen content of the fuel.
4.2 Existing methods allow the hydrogen content to be calculated from other parameters or determined by combustion techniques. The method specified provides a quick, simple, and more precise alternative to these methods.
5. Apparatus 5. I Nuclear Magnetic Resonance Spectrometer3mA lowresolution continuous-wave instrument capable of measuring a nuclear magnetic resonance of hydrogen atoms, and fitted with: 5.1.1 Excitation and Detection Coil, of suitable dimensions to contain the test cell. 5.1.2 Electronic Unit, to control and monitor the magnet and coil and containing: 5.1.2.1 Circuits, to control and adjust the radio frequency level and audio frequency gain. 5.1.2.2 Integrating Counter, with variable time period in seconds. 5.2 Conditioning Block--A block of aluminum alloy drilled with holes of sufficient size to accommodate the test cells with the mean height of the sample being at least 20 mm below the top of the conditioning block (see Fig. 1). 5.3 Test Cells--Nessler-type tubes of approximately 100mL capacity with an external diameter of 33.7 _+ 0.5 mm and an internal diameter of 31.0 _+ 0.5 mm marked at a distance of 51 mm above the bottom of the tube by a ring around the circumference. 5.4 Polytetrafluoroethylene (PTFE) Plugs for Closing Test Cells--Plugs as shown in Fig. 1 made from pure PTFE and a tight fit in the test cells. 5.5 Insertion Rod--A metal rod with a threaded end as shown in Fig. 1 for inserting and removing PTFE plugs from test cells. 5.6 Analytical Balance--Top pan type, capable of weighing the test cells in an upright position to an accuracy of _0.01 g. 3 This method has been written around the Newport Analyzer Mark IIIF (Oxford Analytical Instruments, Ltd., Oxford, England) and the details of the method should be read in conjunction with the manufacturer's handbook. This particular instrument was the only instrument available when the precision program was carried out. Any similar instrument would be accepted into the above method provided the new instrument was adequately correlated and proved to be statistically similar. The Newport Analyzer Mark IIIF is no longer in production and is being replaced by the manufacturer with the Newport 4000. The Newport 4000 model instrument has been demonstrated to provide equivalent results to those obtained with the Mark Ill models which were used to generate the precision data.
This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.03 on Elemental Analysis. Current edition approved March 15, 1992. Published May 1992. Originally published as D 3701 - 78. Last previous edition D 3701 - 87. 2 Annual Book of ASTM Standards, Vol 05.03.
563
~}
D 3701 - (~ 337 2 HOLES 105 DEEP
8 HOLES 105 DEEP
PLASTIC
/ /KNOB
I
LID
I~
METAL INSERTION ROD APPROX 6 ~
39 ¢ 35 ¢ 45~
\
i/
I
i
'
I '
II
:ti,
"ll ~
I
I
I
THREAD
/
1
i
i
I
I
J
L--- I
CONDITIONING BLOCK MATERIAL ALUMINIUM ALLOY
oa-
PLUG MATERIAL PTFE
NOTE--Dimensionsare in millimetms. FIG. 1 Hydrogen Content of Aviation Turbine Fuels
564
L
~
D 3701 - (~) 337 below the 51-mm mark on the test cell. Unscrew the insertion rod carefully without disturbing the plug. 9.4 Place the reference standard in the sample conditioning block. 9.5 Repeat the procedure outlined in 9.1 to 9.4 using the material to be tested.
6. Materials 6.1 Reference agent grade.
Standard--n-Dodecane
of analytical re-
NOTE 1: Warning--Flammable.
7. Sampling 7.1 Take a homogenous sample in accordance with Practice D 4057.
10. Procedure 10.1 Leave the sample and reference standard in the conditioning block for at least 0.5 h to ensure they reach uniform temperature, that is room temperature, before measurements are made. 10.2 Take the reference standard and place it carefully in the coil. When fully entered the top of the test cell should be just above the cover of the spectrometer unit. 10.3 Check that the peaks on the oscilloscope are coincident and if this is not so, adjust the tuning until they are. 10.4 When the reference standard has been in the magnet unit for at least 3 s, push the reset button.
8. Preparation of Apparatus 8.1 Read the following instructions in conjunction with the manufacturer's handbook. Preparation of the instrument is not critical but take care to prevent rapid temperature fluctuations of the instrument and the conditioning block, for example, avoid them in direct sunlight or draught. 8.2 The results obtained during the use of the equipment are susceptible to error arising from changes in the magnetic environment. Exercise care to ensure that there is a mini m u m of magnetic material in the immediate vicinity of the equipment and that this be kept constant throughout the course of a series of determinations. 8.3 Set the instrument controls to the following conditions: NOTE 2--On new NMR instruments with variable gates the gate should be set at 1.5 gauss to comply with nonvariable gate instruments. Radio frequencylevel 20 laA Audio frequencygain 500 on dial Integrationtime 128 s
NOTE 4mIt is important that a delay of this magnitude be allowed before commencing measurement in order that the hydrogen nuclei are fully polarized in the magnetic field. 10.5 After a count time of 128 s the digital display will stop at its final value. Record the integrator counts and push the reset button again and record the second reading. 10.6 Weigh the cell and contents and record the total weight. 10.7 Replace the reference standard in the conditioning block and make similar duplicate readings on the sample to be tested.
8.4 Switch on the main supply to the spectrometer and allow it to warm up for at least 1 h. 8.5 Place a test cell containing sample in the coil and adjust the tuning of the instrument until the two resonance curves on the oscilloscope are coincident. This setting may need to be readjusted during determinations. 8.6 Remove the test cell from the coil and observe that the signal readout is now zero + 3 digits. This should be checked periodically during the series of tests to ensure that no contamination of the coil has occurred.
NOTE 5mMeasurements will be altered by temperature variations in
the sample and reference standard so these must be returned to the conditioning block when measurements are not being made. NOTE 6--The determined hydrogen content will be affected by any instrument drift, slight variations in temperature between the sample and reference standard and loss of sample or reference standard, or both, due to evaporation. Therefore when a series of results are to be determined, sample and reference standard should be measured, weighed and calculated as pairs. When the weight change of the reference standard is greater than 0.01 g between consecutive weighings, the cause of this should be investigated and corrected. Losses are usually due to poor fitting of the PTFE plug while gains will probably be due to contamination of the coil.
9. Preparation of Samples and Standard 9.1 Take a clean, dry test cell and PTFE plug and weigh them together to the nearest 0.01 g and record the weight. Add 30 + 1 m L of the reference standard to the tube, taking extreme care to prevent splashing the liquid above the line inscribed on the tube. The use of a pipet is recommended for this operation. 9.2 Using the insertion rod, push the PTFE plug into the tube until it is just above the liquid-surface, keeping the tube upright. A gentle twisting of the plug as it is inserted will aid the escape of air from the test cell and normally ensure that the lip of the plug is turned up around the entire circumference. Take care to ensure that this is so, as a plug that is not properly inserted will allow rapid sample evaporation and give rise to change in the results obtained.
11, Calculation 11.1 For each sample and reference standard, subtract the weight of the test cell and PTFE plug from total weight of the test cell determined in 10.6 Hydrogen content, mass % = -~R x W_~ x 15.39
Wr
NOTE 3--The insertion of the PTFE plug can be facilitated by inserting a length of thin (less than 0.2 mm diameter) copper wire down the inside surface of the disc until it is approximately 38 mm from the graduation mark and then pushing the PTFE plug down past the wire which is then removed. 9.3 The bottom rim of the plug should be at or slightly 565
where: ST = SR = WR = Wr =
mean of integrator counts on sample under test, mean of integrator counts on reference standard, mass of reference sample, and mass of sample under test
12. Report 12.1 Report the mass percent hydrogen content to the nearest 0.01 mass %.
~)
D
3701 -
337 0.09 mass %
13. P r e c i s i o n and Bias 4
13.1.2 R e p r o d u c i b i f i t y - - T h e difference between two single and independent results obtained by different operatots working in different laboratories on identical test material would, in the long run, in the normal and correct operation of the test method exceed the following value only in one case in twenty:
13.1 The precision of the method as obtained by statistical examination of interlaboratory test results is as follows: 13. I . 1 R e p e a t a b i l i t y - - T h e difference between successive test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method exceed the following value only in one case in twenty:
4
(~)
0.11 mass %
Supportingdataare availableand on loan fromASTMHeadquarters.Request
RR: D02-1 t86.
13.2 B i a s - - A 1977 research report indicated that the hydrogen content determined by this test method is biased high with respect to the expected value for pure known materials.
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of,infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and ff not revised, either reepproved or withdrawn. Your comments are invited either for revision.of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
566
Designation:
D 3710
- 95
An AmericanNationalStandard
Standard Test Method for Boiling Range Distribution of Gasoline and Gasoline Fractions by Gas Chromatography 1 This standard is issued under the fixed designation D 3710; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number m parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
mixture relative to an arbitrarily chosen component. 3.1.4 response factorma constant of proportionality that converts area to liquid volume. 3.1.5 system noise--the difference between the maximum and minimum area readings per second for the first 20 area readings in the blank run. 3.1.6 volume count--the product of the area under a peak and a response factor.
1. Scope 1.1 This test method covers the determination of the boiling range distribution of gasoline and gasoline components. This test method is applicable to petroleum products and fractions with a final boiling point of 500*F (260°C) or lower as measured by this test method. 1.2 This test method is designed to measure the entire boiling range of gasoline and gasoline components with either high or low Reid vapor pressure and is commonly referred to as gas chromatography (GC) distillation (GCD). 1.3 This test method has not been validated for gasolines containing oxygenated compounds (for example, alcohols or ethers). 1.4 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Notes 9, 10, 11, and 15.
4. Summary of Test Method 4.1 The sample is introduced into a gas chromatographic column which separates hydrocarbons in boiling point order. Conditions are selected so as to measure isopentane and lighter saturates discretely. Normal pentane and heavier compounds are not completely resolved but are measured as pseudo components of narrow boiling range. The column temperature is raised at a reproducible rate and the area under the chromatogram is recorded throughout the run. Boiling temperatures are assigned to the time axis from a calibration curve, obtained under the same conditions by running a known mixture of hydrocarbons covering the boiling range expected in the sample. From these data the boiling range distribution of the sample is obtained.
2. Referenced Documents
5. Significance and Use 5.1 The determination of the boiling range distribution of gasoline by GC distillation provides an insight into the composition of the components from which the gasoline has been blended. This insight also provides essential data necessary to calculate the vapor pressure of gasoline, which has been traditionally determined by Test Method D 323. In addition, the Test Method D 86 distillation curve can be predicted using GCD data. See Annex A 1. 5.2 The GCD method facilitates on-line controls at the refinery, and its results offer improved means of describing several car performance parameters. These parameters inelude: (1) car-starting index, (2) vapor-lock index or vaporliquid ratio, and (3) warm-up index. The car-starting and vapor-lock indexes have been found to be mostly affected by the front end of the Test Method D 86 distillation curve (up to about 200*F (93"C)). The warm-up index is affected by the middle and to a lesser extent by the back end of the Test Method D 86 curve, that is, the temperatures corresponding to the 50 to 90 % off range. Since the boiling range distribution provides fundamental information on composition, an improved expression for the above performance parameters may be worked out, even when the boiling range distribution curve is not smooth. Currently, car performance cannot be assessed accurately under such conditions.
2.1 ASTM Standards." D 86 Test Method for Distillation of Petroleum Products2 D323 Test Method for Vapor Pressure of Petroleum Products (Reid Method)2 D 1265 Practice for Sampling Liquefied Petroleum (LP) Gases (Manual Method)z D4057 Practice for Manual Sampling of Petroleum and Petroleum Products3 3. Terminology 3.1 Definitions." 3.1.1 final boiling point (FBP)--the point at which a cumulative volume count equal to 99.5 % of the total volume count under the chromatogram is obtained. 3.1.2 initial boiling point (IBP)--the point at which a cumulative volume count equal to 0.5 % of the total volume count under the chromatogram is obtained. 3.1.3 relative molar response--the measured area of a compound divided by the moles present in the synthetic This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.04.0H on Chromatographic Methods. Current edition approved Sept. 10, 1995. Published November 1995. Originally published as D 3710 - 78. Last previous edition D 3710 - 93. 2 Annual Book o./ASTM Standards, Vol 05.01. 3 Annual Book oJ ASTM Standards, Vol 05.02.
6. Apparatus 6.1 ChromatographmAny gas chromatograph may be 567
iI~) D 3710 TABLE
1
Repeatability
as a Function
of Percent
Repeatability, Volume Percent Recovered, dT/dV:
Recovered
dT/dV
and
r, °F (*C)
0
2(1)
4(2)
6(3)
6(4)
10(6)
12(7)
14(8)
20(11 )
30(17)
IBP
2(1)
2(1)
2(1)
2(1)
2(1)
2(1)
2(1)
2(1)
2(1)
1
2(1)
2(1)
2(1)
2(1)
2(1)
2(1)
2(1)
2(1)
--
5 10
2(1)
2(1)
2(1)
2(1)
2(1)
2(1)
2(1)
2(1)
--
2(1) ---
2(1) 2(1 ) 2(1 )
2(1) 3(2) 3(2)
2(1) 4(2) 4(2)
2(1) 5(3) 5(3)
2(1) 7(4) 7(4)
2(1) 10(6) 10(6)
2(1) . 14(8)
--
--
--
95 99
__A .
__
3(2)
9(6)
.
5(3) .
7(4)
.
2(1 ) .
-6(3)
--6(3)
FBP
.
.
.
6(3)
6(3)
20 30
to 9 0
.
.
.
.
.
.
.
2(1) . 19(10) 13(7) 6(3)
.
40(22) 2(1)
.
6(3)
6(3)
CONCENTRATION DATA Repeatability, r, Component
C3
iC4
nC4
iC5
-0.02 0.02 ----D
0.02 0.02 0.03 0.03 0.04 0.05 0.05 0.06 0.07
--------D
~
0.07
--------_ --
Volume 0.10 0.15 0.20 0.4 0.6 0.8 1.0 1.2 1.4 1.6 2 4 6 8 10 12 14 16 18 20 22
--~ -~ ---~ ~ --
A (_) Outside the range observed in the cooperative
-0.11 0.22 0.32 0.43 0.54 0.65 0.76
0.86 ----
0.25 0.28 0.30 0.32 0.34 0.36 0.39 0.41 0.43 0.45
study
used that meets the performance requirements in Section 8. Place in service in accordance with manufacturer's instructions. Typical operating conditions are shown in Table 3. 6.1.1 Detector--Either a thermal conductivity or a flame ionization detector may be used. Detector stability must be such that the sensitivity and baseline drift requirements as defined in Section 8 are met. The detector also must be capable of operating continuously at a temperature equivalent to the m a x i m u m column temperature employed, and it must be connected to the column so as to avoid any cold spots.
15 s for propane and of allowing elution of the entire sample within a reasonable time period. Subambient capability may be required. The programming rate must be sufficiently reproducible to meet the requirements of 8.7. NOTE 3--If the column is operated at subambient temperature, excessively low initial column temperature must be avoided, to ensure that the stationary phase remains liquid. The initial temperature of the column should be only low enough to obtain a calibration curve meeting the specifications of this test method.
NOTE l--Care must be taken that the sample size chosen does not allow some peaks to exceed the linear range of the detector. This is especially critical with the flame ionization detector. With thermal conductivity detectors, sample sizes of the order of 1 to 5 laL generally are satisfactory. With flame ionization detectors, the sample size should not exceed I IsL. NOTE 2--It is not desirable to operate the detector at temperatures much higher than the maximum column temperature employed. Operation at higher temperatures only serves to shorten the useful life of the detector, and generally contributes to higher noise levels and greater drift.
6.1.2 Column TemperatureProgrammer--The chromatograph must be capable of program temperature operation over a range sufficient to establish a retention time of at least
568
6.1.3 Sample Inlet System--The sample inlet system must be capable of operating continuously at a temperature equivalent to the maximum column temperature employed, or provide on-column injection with some means of programming the entire column, including point of sample introduction up to the maximum temperature required. The sample inlet system must be connected to the chromatographic column so as to avoid any cold spots.
6.1.4 Flow Controllers--Chromatographs must be equipped with constant-flow controllers capable of holding carder gas flow constant to + 1 % over the full operating temperature range. 6.2 Sample Introduction--Sample introduction may be either by means of a constant-volume liquid sample valve or by injection with a microsyringe through a septum. If the sample is injected manually, cool the syringe to 0 to 4"C (32 to 40°F) before taking the sample from the sample vial.
tl~) D 3710 TABLE
2
Reproducibility
as n Function
of Percent
Recovered
dT/dv
end
Reproducibility, R, *F (*C) A Volume Percent Recovered, dt/dv: IBP 1 5 10 20 3 0 to 90 95 99 FBP
0 7(4) 5(3) 5(3) 6(3) 5(3) 6(3) _ e . .
2(1 ) 7(4) 5(3) 5(3) 6(3) 7(4) 9(5) __ .
4(2) 8(4) 5(3) 5(3) 6(3) 11 (6) 13(7) 11 (6) .
. .
.
.
6(3) 8(4) 6(3) 5(3) 6(3) 16(9) 20(11) 16(9) . .
8(4) 8(4) 6(3) 6(3) 6(3) 23(13) 27(15) 23(13) . . .
10(6) 8(4) 6(3) 5(3) 5(3) 30(17) 36(20) 30(17) .
12(7) 8(4) 6(3) 6(3) 3(7) . 46(26) 36(21 )
.
14(8) 8(4) 6(3) 6(3) . . 55(31) 46(26) 20(11 )
.
.
20(11 ) 30(17) 9(5) 1 0(6) ----. . . . ----24(13) 33(18) 19(11 ) 26(14)
40(22) 12(7) ---
--36(20) 36(20)
A For thermal conductivity detectors. For flame ionization detectors (FID), reproducibilities, R, a r e the s a m e e x c e p t in the 2 0 to 95 % recovered range where: RRO = 0 . 9 0 RTCO Reproducibility, R C3 Detector
iC4
Detector Bias (FID-TCD)
nC4
Both
TCD
FID
-0.13 0.13 --~ ----------~ -. . .
0.10 0.10 0.10 0.12 0.13 0.15 0.16 0.18 0.19 0.20 ~ ---~ -~ --
0.09 0.11 0.13 0.20 0.27 0.34 0.41 0.48 0.55 0.62 ~ ~ --~ ~ -~ . . .
TCD
iC5 FID
TCD
C3
iC4
nC4
-0.00 0.00 ~ ~ -~ -~ -~ ~ ~ ----~ ~ ~ ~
0.00 0.00 0.00 -0.01 -0.03 -0.04 -0.05 -0.06 -0.07 -0.09 ----~ ---~ u ~
-~ ----~ ~ ---0.33 -0.28 -0.24 -0.19 -0.14 -0.10 -0,05 -0.01 -~ --
iC5
FID
Volume 0.10 0.15 0.20 0.4 0.6 0.8 1.0 1.2 1.4 1.6 2 4 6 8 10 12 14 16 18 20 22
. . .
. . .
0.28 0.57 0.85 1.14 1.42 1.70 1.99 2.27
1.62 1.91 2.19 2.48 2.76 3.04 3.33 3.61
. . .
0.79 0.98 1.15 1.35 1.54 1.72 1.91 2.09 2.28 2.48
0.29 0.48 0.66 0.85 1.04 1.22 1.41 1.59 1.78 1,97
------0.27 -0.14 0.00 +0,14 +0.28 +0.42 +0.55 +0.69 +0.83 +0.97
e (_) O u t s i d e the range observed in the cooperative study.
NOTE 4--Automatic liquid-sampling devices or other sampling means, such as sealed septum-capped vials, may be used, provided no loss of light ends occurs. The system must be operated at a temperature sufficiently high to vaporize completely hydrocarbons with an atmospheric boiling point of 500*F (260"C), and the sampling system must be connected to the chromatographic column so as to avoid any cold spots.
temperature to reduce baseline shifts due to bleeding of column substrate. NOTE 5--The column can be conditioned very rapidly and effectivelyby the following procedure: (1) Disconnect column from detector. (2) Purge the column thoroughly at ambient temperature with carrier gas. (3) Turn off the carrier gas and allow the column to depressurize completely. (4) Raise the column temperature to the maximum operating temperature and hold at this temperature for at least 1 h with no flow through the column. (5) Cool the column to at least 100°C before turning on carrier gas again. (6) Program the column temperature up to the maximum several times with normal carrier gas flow. The column then should be ready for use. NOTE 6wAn alternative method of column conditioning, which has been found effective for columns with an initial loading of l0 % liquid phase, consists of purging the column with carrier gas at the normal flow rate while holding the column at maximum operating temperature for 12 to 16 h.
6.3 Recorder--A recording potentiometer or equivalent with a full-scale response time of 2 s or less may be used. 6.4 Column--Any column and conditions may be used, provided, under the conditions of the test method, separations are in order of boiling points and the column meets the performance requirements in Section 8. See Table 3 for columns and conditions that have been used successfully. Since a stable baseline is an essential requirement of this test method, provisions must be made to compensate for column bleed. Traditionally this is done by using matching dual columns and detectors. At best, this procedure is only marginally successful. An even more satisfactory procedure is to record the area profile of the column bleed during a blank run, and subtract this profile from subsequent sample runs, as outlined in 11.1. 6.4.1 Column Preparation--Any satisfactory method, used in the practice of the art, that will produce a column meeting the requirements of Section 8, may be used. The column must be conditioned at the maximum operating
6.5 Integrator--Means must be provided for determining the accumulated area under the chromatogram. This can be done by means of a computer, or automatic operation can be achieved with electronic integration. A timing device is used to record the accumulated area at set time intervals. The same basis for measuring time must be used to determine 569
~) D 3710 TABLE 3
Gas Chromatography Column and Conditions
Column: Liquid phase, material weight % Solid support, material mesh size Length, m (ft) Outside diameter, mm (in.)
UCW-982 10 Chromosorb P 80/100 0.5 (1 .S) 6.4 (1/4)
Supelco 2100 20 Chromosorb W 80/100 1.5 (5) 3.2 (1/5)
UCW-98 10 Chromosorb G 60/80 0.9 (3) 6.4 (1/4)
OV-101 10 Chromosorb P 60/80 1.2 (4) 3.2 (1/8)
UCW-98 10 Supelcoport 80/100 1.5 (5) 3.2 (1/8)
-30 250 250 250
40 250 250 300
-20 200 345 345
0 250 250 250
0 230 250 230
10.6 He 50 3 150 mA
16 He 30 2 160 mA
10 He 60 3 135 mA
15 He 29 2 ...
16 He 30 1 175 mA
TC automatic syringe integrating A/D 2
TC syringe integrating A/D 1/2
TC syringe integrating A/D 5
Temperatures: Initial column temperature, =C Final column temperature, =C Detector temperature, *C Injection zone temperature, *C Operating Variables: Program rate, *C/rain Carrier gas flow rate, cma/min Sample size, ~tL Detector voltage (or mA)
Instrument: Detector type Sampling system Area measurement method Time slices per second
retention times in the calibration, the blank, and the sample. If an electronic integrator is used, the maximum area measurement must be within the linear range of the inte= grator. 6.6 Sample ContainersmPressure cylinders or vials with septums should be provided for the calibration mixture and samples to avoid loss of light ends. 6.7 System~Any satisfactory combination of the above components that will meet the performance requirements of Section 8. 7.
TC
TC
valve
valve
time slice 5
time slice 1/2
for use with flame ionization detectors. (Warning--See Notes 10 and 11.) NOTE 10: W a r n i n g - - H e l i u m , nitrogen, a n d argon are compressed
gases under high pressure. NOTE 1 1: Warning--Hydrogen is an extremely flammablegas under high pressure. 7.3 Liquid Phase for Columns: NOTE 12--The following materials have been used suceessfuUy as liquid phases: Silicone gum rubber GE-SE-304 Silicone gum rubber OV-I s Silicone gum rubber OV-1015 Silicone gum rubber Snp¢lco 21006 Silicone gum rubber UC-W987
Reagents and Materials
7.1 Calibration MixturemA synthetic mixture of pure liquid hydrocarbons of known boiling point covering the boiling range of the sample. At least one compound in the mixture must have a boiling point equal to or lower than the initial boiling point of the sample, and one compound must have a retention time greater than any component in the sample. The concentration of all compounds heavier than n-butane must be known within 0.1%. The synthetic composition shown in Table 2 should be used for gasoline analysis. Compounds necessary for evaluation of system performance are noted in Table 4.
7.4 Solid Support--Usually crushed fire brick or inert diatomaceous earth such as Chromosorb P, G, or W, 8 acid-washed, dimethyl silanized. Sieve size and support loading should be such that it will give optimum resolution and analysis time. In general, support loadings of 3 to 10 % have been found most satisfactory but higher ones have been used as shown in Table 3. 8.
S y s t e m Performance
NOTE 7--If the sample contains significant quantities of compounds
8.1 Resolution--For samples containing isopentane and
that can be identified on the chromatogram, these peaks may be used as
lighter materials, the system must be able to identify the beginning and end of isopentane and lighter saturated compounds as they elute from the column. Individual peaks must be resolved from adjacent peaks so that the height at the valley above the baseline is not more than 5 % of,the height of the smaller peak adjacent to it. The resolution, R, between nCi2 and nCt3 must be between 2 and 4 when calculated in accordance with the following equation as shown in Fig. l:
internal boiling point calibrations. NOTE 8--Two calibration mixtures can be used for convenience. One that contains known concentrations of isopentane and heavier compounds can be used for determining response factors, sensitivity, and concentration repeatability. The other would contain a complete boiling range of compounds including propane, butane, and isobutane, whose concentrations are known only approximately. It would be used for measuring resolution, skewness, retention time repeatability, polarity, and retention time-boiling point relationship. NffrE 9--If the sample is known to contain more than 5 % benzene, 2,4 dimethylpentane should be replaced with benzene in the calibration mixture. (WarningMBenzeneis poisonous and carcinogenic,harmful or fatal if swallowed.)
7.2 Carrier GasmHelium or hydrogen for use with thermal conductivity detectors. Nitrogen, argon, or helium 570
4 Registered trademark s Registered trademark 6 Registered trademark 7 Registered trademark s Registered trademark
of General Electric Co. of Ohio Valley Specialty Chemical Co. of Supelco, Inc. of Union Carbide Co. of Johns-Manville Co.
~
D 3710
g n C12
n C1}
E rG u')
r~3 Z 0 J
¢&3
Y]. sec. Y2' sec. FIG. 1
Column Resolution
R = 2D/(Y, + }'2)
(1)
0.05
where: D = time, s, between nC~2 and nC~3 apexes, Y, = peak width of nCz2, s, and Y2 = peak width of nC~3, s. 8.2 Sensitivity and NoisemThese criteria test the sensitivity and noise of the total system. From the first 20 readings or time intervals of the blank run, calculate the noise as the difference between the maximum area reading per second minus the minimum reading per second. From the measurements on the calibration mixture, calculate the signal/noise ratio, as follows:
A/(N x S)
TIME FIG. 2
where: A = total area of the hexane peak, N = noise, and S = width of the hexane peak in seconds. This value must not be less than 10 for each 0.05 volume % of hexane in the calibration mixture, for example, 200 for 1%. If the noise is undetectable, assume the noise to be 1 count per second. 8.3 Drift--From the blank run, calculate by the following test procedure, a total area measured after the start of the run
Peak Number
Compound Identification
1e
nCa
2e
isoC4
3e 4a 5 6 7c 8D 9 10 o 11 12c 13 c 14 15 c 16 c 17 c 16 19
nC4 isoC s
nCs 2-MeC 5 nCe 2,4-DiMeCs nC7 Toluene nCe p-Xyiene n-Propylbenzene nClo n-Butylbenzene nC12 nCla nC14 nC15
Peak Skewness
until the end of the run. Adjust the apparatus so that all measurements can be read whether positive or negative. On some equipment such as integrators, readings will need to be positive and increasing in value. Obtain the absolute difference between the average area reading in the first five time intervals and the individual readings in each time interval from the start of the blank run until the end. Sum these differences to obtain the total area for the blank. The total area measurement from the blank run must not be greater than 2.0 % of the total area measurement of the calibration mixture. 8.4 Skewing of Peaks--Calculate the ratio A/B on peaks in the calibration mixture as shown on Fig. 2. A is the width in seconds of the part of the peak ahead of the time of the apex at 5 % of peak height, and B equals the width in seconds of the part of the peak after the time of the apex at
(2)
TABLE 4
H
Calibration Mixture
NBP, °F
Relative Density, a 60/60°F
Approximate Volume, %
Typical Thermal Conductivity Response Factors
-44 11 31 82 97 140 156 177 209 231 258 281 319 345 362 421 456 486 519
0.5077 0.5631 0.5844 0.6248 0.6312 0.6579 0.6640 0.6772 0.6882 0.8719 0.7068 0.8657 0.8666 0.7341 0.8646 0.7526 0.7601 0.7667 0.7721
1 3 10 9 7 5 5 5 9 10 5 12 4 3 3 3 2 2 2
1.15 1.14 1.07 1.08 1.03 1.03 1.01 1.07 1.00 0.89 0.98 0.90 0.94 0.99 0.93 1.00 1.02 1.04 1.05
A "Selected Values of Properties of Hydrocarbons and Related Compounds," American Petroleum Institute Project 44, Table 23-2, April 1956. a Necessary if sample contains isopentane and lighter compounds. c Necessary for system evaluation, o Replace 2-methylhexane (2-MeCe) or benzene if the sample contains more than 5 • benzene.
571
t i n D 3710
5 % of peak height. This ratio must not be less than 0.5 nor more than 2.0.
with the known percent. The difference between the calculated and known percentages must not be greater than 0,5.
NOTE 13--A ratio of more than 2.0 is probably due to overloading of the column. This can be corrected by smaller sample size, higher loading of the liquid phase on the packing, or larger diameter column. A ratio of less than 0.5 probably indicates tailing, overloading the detector, or loss of liquid substrate. The column must be changed when tailing becomes excessive. It is possible that the peak shape can be distorted due to a combination of these reasons.
9. Sampling
8.5 Retention Time--The system must be sufficiently repeatable when testing the calibration mixture to obtain peak maxima retention time repeatability ( m a x i m u m difference between duplicate results) of 3 s for isopentane and lighter compounds, if present. The m a x i m u m difference between duplicate results of retention times of the normal pentane and heavier compounds must not be greater than a time equivalent to 3"C (2*F). In addition, the retention time of the apex of the first peak in the calibration mixture should be at least 15 s. 8.6 Polarity--Calculate the boiling point retention time relationship specified in 10.2.2, using only the n-paraffins. Using the observed retention time of the aromatic compounds, calculate their apparent boiling points. Compare the apparent boiling points of the aromatics with their known boiling points. The apparent boiling point of the aromatic compounds must not deviate more than 10*F (6"C) from linearity or normal paraffins in the calibration mixture. 8.7 Area Measurement--The area measurement may be made by an electronic integrator or an analog-to-digital converter in conjunction with a computer. As the run progresses, the amount of material eluted from the column is measured from time zero in time slice areas or counts at specified time intervals. The counts are summed continuously, and the time intervals are equated to equivalent temperatures using the calibration curve generated in 10.2.2. Continue measurement for 2 rain after the apex of the last peak or until the chromatogram returns to a constant baseline at the end of the run. Duplicate results on consecutive runs on the area percent of the compounds in the calibration mixture must not differ by more than 0.1%. 8.7.1 Time intervals need not be uniform throughout the run. However, it is important that all measurement be on the same basis for the blank, calibration, and sample. No interval shall be greater than 0.5 % of the total length of the run. In addition, in order to facilitate the measurement of light ends, the size of the time intervals for the isopentane and lighter compounds should be small enough to allow measurement of their areas and times to peak maxima. NOTE 14--The end of the run can be defined by using the following algorithm: find the time where the rate of change of the chromatographic signal is less than or equal to a specified value (0.05 mV/min and 0.001% of the total area under the chromatogram have been used successfully). Then search for i min before and after that time. The point where the number of counts per slice is at a minimum in that 2-rain period is defined as the end of the run.
8.8 Difference from Calibration Mixture--Multiply the area of each peak in the calibration mixture by the liquid volume response factor calculated in 11.2, and normalize the volume percent of each compound so that the volumes of all compounds heavier than n-butane add up to 100.0. Compare the volume percent of each compound heavier than n-butane 572
9.1 Samplingfrom Bulk Storage: 9.1.1 Cylinder--Refer to Practice D 1265 for instructions on introducing samples into a cylinder from bulk storage. The cylinder should be pressurized with carrier gas to a pressure of at least 345 kPa (50 psi) above the vapor pressure of the sample (Warning--See Note 15). If the sample is to be transferred to another vessel such as a vial with septum, the cylinder must be cooled to a temperature between 32 and 40*F (0 and 4"C). NOTE 15: Warning--Gasoline is extremely flammable. Vapors are harmful if inhaled.
9.1.2 Open Containers--Refer to Practice D 4057 for instructions on introducing samples into open-type containers from bulk storage. Cool the container and its contents to 32 to 40*F (0 to 4"C) before removing any sample from it. 9.2 Sampling from Open-Type Containers--Follow the instructions in Test Method D 323 for transferring material from an open-type container. 10. Procedure
10.1 Blank--After conditions have been set to meet performance requirements, program the column temperature upward to the m a x i m u m temperature to be used. Following a rigorously standardized schedule, cool the column to the selected starting temperature. At the exact time set by the schedule, without injecting a sample, start the column temperature program. Measure and record the area in each time interval from the start ofthe run until the end of the run as specified in 8.7. Make a blank run at least daily. I0.1.1 In order for the blank run to be valid, it must meet the drift requirement specified in 8.3. In addition, no peaks must be found such that the difference in area readings per second in consecutive time intervals be greater than five times the noise. If the noise is not detectable, assume it to be 1 count per second. NOTE 16--The identification of a constant baseline at the end of the run is critical to this test method. Constant attention must be given to all factors that influence baseline stability, such as substrate bleed. NOTe 17--Some gas chromatographs have an algorithm built into their operating software, which causes a mathematical model of the column bleed profile to be stored in memory. This profile is subtracted automatically from the detector signal on subsequent runs to compensate for the column bleed. 10.2 Calibration: 10.2.1 Using the same conditions described in 10.1, inject the calibration mixture into the chromatograph. Record the data in such a manner that retention time of peak maxima and peak area of the individual components are obtained. As noted in 8.7, this can be done by means of a computer or integrator. NOTE 18--When determination of peak maxima and peak area is done by the time slice technique, the followingalgorithms can be used to verify the start of peak, end of peak, and peak maxima: A peak is defined as starting in that time slice in which the rate of change of the chromatographic signal is greater than a specified value (0.05 mV/min and 0.001%/s have been used successfully). This criterion must be confirmed for two consecutive time segments in order to be valid. Once a peak is detected, the end is determined by one oftwo criteria. The first
~
D 3710 versus the c o r r e s p o n d i n g n o r m a l boiling p o i n t in degrees Celsius (or Fahrenheit) as shown in Fig. 4. I f the sample is k n o w n to c o n t a i n less t h a n 5.0 % aromatics, d o not include a r o m a t i c c o m p o u n d s in the retention t i m e calibration curve. NOTE 19--For best precision, the calibration curve should be essentially a linear plot of boiling point versus retention time. In general, the lower the initial boiling point of the sample, the lower will be the starting temperature of the chromatographic column. If the starting temperature is too high, there will be considerable curvature at the lower end of the curve, and loss of precision in that boiling range. Since it is impractical to operate the column so as to eliminate curvature completely at the lower end of the curve where initial boiling points below ambient temperature are encountered, at least one point on the curve should have a boiling point lower than or equal to the initial boiling point of the sample. Extrapolation of the curve at the upper end is more accurate, but for best accuracy, calibration points should bracket the boiling range of the sample at both the low and high ends.
AREA COUNTS
i-i
I
i+l i+2 TIME
FIG. 3
Determination of Time to Peak Maxima
10.2.3 T h e boiling p o i n t retention t i m e calibration curve m u s t be checked at least daily by either the calibration m i x t u r e o r a s e c o n d a r y standard o f k n o w n boiling point characteristics.
applies when there is good resolution between peaks. The peak can be defined as ending when the rate of change of the chromatographic signal is less than the value specified above. The second criterion applies when resolution between peaks is not complete. The first peak ends when, after the apex has passed, the area per time segment reaches a minimum and starts to increase. The retention time of peak maxima can be determined by the following equation, as shown in Fig. 3:
NOTE 20--If peaks in the sample are used as boiling point calibration marks, the calibration mixture need not be run. However, it may prove helpful in establishing identity of peaks in the sample to run the calibration mixture once. Furthermore, precision may be improved in some cases by adding to the sample an n-paraffin, selected so as to be resolved completely from the sample, to serve as an additional boiling point calibration. Plot the retention times of the peaks versus the corresponding atmospheric boiling points to obtain the calibration
tma x = t, + (ti+ I - t,) A,+,/(Ai-~ + A,+O (3) where: tmax = retention t i m e o f peak m a x i m a , ti = time to st~irt o f segment i, 6+, = time to start o f segment i + 1, Ai+l = a r e a o f segment that starts at t;+,, a n d A i _ t = area o f segment that starts at ti_~. F o r systems in which the o u t p u t is in units other t h a n millivolts, a n equivalent measure o f the slope m a y be used.
curve.
10.3 S a m p l i n g : 10.3.1 Using the exact conditions a n d t i m e basis as were used in the b l a n k a n d calibration, inject t h e s a m p l e into the c h r o m a t o g r a p h . Disregarding peaks (if any) before propane,
10.2.2 Plot the retention time o f the m a x i m a o f each peak 60C
50
°~
40
i,o lo
-lo
0
i00
200
300
I 400
I soo
I 600
RETENTION TIME, SECONDS
FIG. 4
Typical Calibration Curve
573
~
~,.~,...=
,~[
D 3710
HORIZONTAL
~)~'SLICEWIDTH
FIG.5 GCDDriftCorrection Ao ffi A,
measure and record the area of each time segment at time intervals as specified in 8.7.
- aa/~ - ( 0 - Oa)
(4)
where: ACi •corrected area of segment i, sample or calibration,
11. Calculation correction is not necessary if the drift is less than 0.5 % as calculated in 8.3. 11.1.1 Correct the blank, calibration, and sample runs for initial offset from zero by subtracting from each time interval the average area of the first five time intervals in the corresponding run. Omit from the average any readings (extraneous peaks) that are more than three times the noise as defined in 8.2. 11.1.2 Correct the calibration and sample for drift by subtracting the corrected area of each time segment of the blank from the corresponding segment of the sample 11.1 D r i f t C o r r e c t i o n - - D r i f t
NOTE 2 l--The corrected area for each time segment is calculated as follows:
A; =uncorrected area of segment i, A~i •area of corresponding segment of blank, O •offset from run, sample or calibration, and OB =offset from blank. 11.1.3 An alternative procedure of correcting for drift and offset is by subtracting a triangular segment of area based on the sample itself as illustrated in Fig. 5. NOTE 22--For the scheme shown in Fig. 5, the corrected area for each time segment is calculated as follows: A o = A, -
o + CA~- A o) \if- to/j
where: =corrected area of segment/, sample or calibration,
Ao
2.0 EXPERIMENTAL MEASUREMENTS
1.8
. /
LEAST SQUARES REGRESSION 1.6 ttl U~
/
SYSTEM NOT OPERATING PROPERLY
1.4
= o
1.2
/" /"
1.0
/" 0.8'
0.4
OF LIGHT ENDS
/
0.2
0.040 ~C3 nCI,604
"~5 .c n~7 .c i ]6
80
I00
.C,o
IS l ....
Jl
,
120
140
160
.c12-c13 .c14 =c15 I
l i 180
It 200
MOLECULAR WEIGHT FIG. 6
Relative Molar Response versus Molecular Weight for n-Paraffins
574
I 220
~
D 3710
TABLE 5 ReportFormat Percent Off
OF
Percent Off
response factor relative to the factor for nC 7 for all compounds iC5 and heavier: Response factor, F, = (V i x Ac)/(V o x Ac,) (6) where: Fi = response factor of the compound, Ac, = corrected area for each pure compound, II,. = volume percent from the calibration mixture, A c o = corrected area of nC 7, and Iio = volume percent of nC 7 in the calibration mixture. 11.2.2 Determine the response factors for propane, isobutane, and n-butane in the following manner. Calculate the relative molar response, RMR, for each of the normal paraffins starting with nC5 as follows:
OF
0.5 (IBP) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
51 52 53 54 55 56 57 58 59 6O 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 99.5 (FBP)
Component
Volume Percent
R M R t = (Ac,
X
mo)/(Aco
×
rni)
(7)
where: RMRi = relative molar response for the compound, mi = mole percent of the compound in the calibration mixture, and mo = mole percent of nC 7 in the calibration mixture. The RMR is a linear function of molecular weight, s The measured RMR's are fit to the linear equation RMR = a M W + b employing the least squares technique. The RMR for propane and n-butane is calculated using the resulting equation. For isobutane, use the R M R measured for n-butane. Calculate response factors for these three components as follows: Response factor, F t = (MWi x RMR o x Deno)/(MW o x RMRi x Den/) (8) where: MWi = molecular weight of the compound, MWo = molecular weight of nC 7, R M R i = relative molar response of the compound, R M R o = relative molar response of nC7, Dent = relative density of the compound, and Deno = relative density of nC 7. Typical response factors along with relative densities are shown in Table 2. NOTE 23--If the concentrations of propane and butane in the calibration mixture are known, differencesnoted between the observed and calculated response factors indicate loss of front-end components. If a fresh calibration mixture is used, these differencescan be indicative of sampling problems. Deviation of the response factors of the heavier components from the straight-line relationship could indicate problems in volatilizing the sample. Possible reasons include injection port temperature being too low, insufficient carrier gas flow, or lack of homogeneity in sampling. Figure 6 illustrates these effects.
n-Ca iso-C 4 n-C 4 iso-C 5
11.2.3 Apply the response factor for each compound in the calibration mixture to the corrected areas of all time intervals in the sample that falls between a point (a) that is halfway between the observed apex of that compound and the observed apex of that compound and the observed apex of the preceding compound, and a point (b) that is halfway between the observed apex of that compound and the observed apex of the succeeding compound. The response factors used may differ according to sample type. For
Ai =uncorrected area of segment i, Ao =average area of last five segments before start of first
peak, Af = area of first segment after end of last peak, ti =time to segment i from beginning of run, to =time to last segment before start of first peak, and tf =time to first segment after end of last peak. 11.1.4 In cases where the calibration is peak-integrated instead of time-sliced, the drift corrections need not be applied. 11.2 R e s p o n s e Factors." 11.2.1 Using the corrected areas from the calibration run and composition of the calibration mixture, calculate the
s Messner, A. E., et al, "Correlation of Thermal Conductivity Cell Response with Molecular Weight and Structure," Analytical Chemtstry. ANCHA, Vol 3 I, No. 2, February 1959, pp. 230-233.
575
~
D 3710 12.2 Report volume percent of isopentane and lighter compounds individually. This provides a more absolute basis for describing commercial gasolines than the IBP. Note 24--Some olefins will be measured with butane and isopentane. See 11.3.4.
commercial gasolines, typical response factors are shown in Table 2. For gasoline blending components containing small amounts of aromatics, such as alkylates, the aromatic response factors should be omitted and only paraffin response factors used. The response factors measured are used until such time as the detectors or columns are changed or there is some reason to suspect that their values are no longer applicable.
13. Precision and Bias 13. I The precision of this test method depends upon the shape of the boiling range distribution curve. Both the repeatability and reproducibility vary with percent recovered and the rate of change of temperature with percent recovered: dT/dV (9) where: T -- temperature, and V = percent recovered. The slopes, dT/dV, are computed from points adjacent to the selected percent recovered points, for example, for 60 %, the temperatures at 58, 59, 61, and 62 %. 13.2 The following criteria should be used for judging acceptability of results. These data were generated from cooperative analyses of gasolines with a wide range of volatilities. 13.2.1 Repeatability--The difference between successive test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the values shown in Table 1 only in one case in twenty. 13.2.2 Reproducibility--The difference between two single and independent results, obtained by different operators working in different laboratories on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the values shown in Table 1 only in one ease in twenty. 13.3 Bias--Bias cannot be determined since there is no acceptable reference material suitable for determining the bias for the procedure in this test method.
11.3 Calculation of Sample: 11.3.1 For each time segment between the beginning of the first peak and the end of the last peak, multiply the area by the suitable response factor to get volume counts. Divide the cumulative volume counts at the end of each interval by the total volume counts and multiply by 100. This will give the cumulative percent of sample recovered at each interval. 11.3.2 Tabulate the cumulative volume percent recovered at each interval and the retention time at the end of the interval. Using linear interpolation where necessary, determine the retention time associated with 0.5 and 99.5 volume % recovered. These are respectively the initial and final boiling points. Determine the retention time for each volume percent off between 1 and 99. 11.3.3 For each volume percent and its associated retention time, determine the corresponding temperature from the calibration curve (10.2.2). Use linear interpolation between all calibration points. 11.3.4 Identify individually the propane through isopentane peaks by comparing the retention time of each peak to the corresponding retention time in the calibration run. Check to see that the retention time of the apex of the propane, iso-, and normal butane and isopentane peaks is within a time equivalent to 5°F (3"C) of the calibration run. Note any isopentane or lighter component that is apparently absent. Calculate the volume percent of the individual compounds by using the suitable response factors. Include any peaks between normal butane and isopentane with the normal butane peak. 12. Report 12.1 Report the temperature to the nearest I*F (0.5"C) at 1% intervals between 1 and 99 %, and at 0.5 % and 99.5 %. The report format is shown in Table 5. Other formats based on users' needs may also be employed.
14. Keywords 14.1 boiling range distribution; gas chromatography; gasoline; gasoline blending component
576
~
D 3710
ANNEXES
(Mandatory Information) A1.
CALCULATION AND P R E D I C r l O N empirically determined constants AI.3 Predict Test Method D 86 distillation curve from the GCD boiling range distribution curve by an empirical correlation of the general form:
AI. 1 Results obtained by this test method may be used to the vapor pressure of the gasoline sample, including its Reid vapor pressure (RVP) and to predict the Test Method D 86 distillation curve. AI.2 Calculate Reid vapor pressure by the following general equation: R V P = Z aV, ¢-bt. (AI.1)
a,b =
calculate
Percent off, D 86i = Z Aij x Vj where: A o = empirically determined constants, and Vj = percent off by GCD at outpoint j.
where: V i = volume fraction eluted in cut i, t, -- boiling point of cut i, as determined from the calibration curve, and
The American Society for Testing and Materials takes no position respecting the vafidity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard Is subject to revision at any time by the responsible technical committee and must be reviewed every five years and ff not revised, e#her reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
577
(A 1.2)
D e s i g n a t i o n : D 3 7 6 0 - 9 3 ~1
Standard Test Method for Analysis of Isopropylbenzene (Cumene) by Gas Chromatography I This standard is issued under the fixed designation D 3760; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year &last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or rcapproval. E~NOT~--Value in 10.1 corrected editorially in July 1995.
sample of isopropylbenzene. The prepared sample is mixed and analyzed by a gas chromatograph equipped with a flame ionization detector (FID). The peak area of each impurity and the internal standard is measured and the amount of each impurity is calculated from the ratio of the peak area of the internal standard versus the peak area of the impurity. Purity by GC (the isopropylbenzene content) is calculated by subtracting the sum of the impurities found from 100.00. Results are reported in weight percent.
1. Scope 1.1 This test method covers the determination of the purity of isopropylbenzene (cumene) by gas chromatography. 1.2 This test method has been found applicable to the measurement of impurities such as nonaromatic hydrocarbons, benzene, ethylbenzene, t-butylbenzene, n-propylbenzene, alpha-methylstyrene, sec-butylbenzene, and diisopropylbenzene, which are common to the manufacturing process of isopropylbenzene. Limit of detection for these impurities is 10 mg/kg (see 5.1). 1.3 The following applies to all specified limits in this standard: for purposes of determining conformance with this standard, an observed value or a calculated value shall be rounded off "to the nearest unit" in the last right-hand digit used in expressing the specification limit, in accordance with the rounding-off method of Practice E 29. 1.4 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 7.
4. Significance and Use 4.1 This test method is suitable for setting specifications on the materials referenced in 1.2 and for use as an internal quality control tool where isopropylbenzene is produced or is used in a manufacturing process. It may also be used in development or research work involving isopropylbenzene. 4.2 This test method is useful in determining the purity of isopropylbenzene with normal impurities present including diisopropylbenzenes. If extremely high boiling or unusual impurities are present in the isopropylbenzene, this test method would not necessarily detect them and the purity calculation would be erroneous. 4.3 Cumene hydroperoxide, if present, will yield decomposition products that will elute in the chromatogram thereby giving incorrect results. 4.4 The nonaromatic hydrocarbons commonly present from the isopropylbenzene manufacturing process will interfere with the determination of benzene when Column A in Table 1 is used. 4.5 The internal standard must be sufficiently resolved from any impurity and the isopropylbenzene peak.
2. Referenced Documents
2.1 ASTM Standards: D3437 Standard Practice for Sampling and Handling Liquid Cyclic Products 2 E 29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications3 E 260 Practice for Packed Gas Chromatography 3 E 355 Practice for Gas Chromatography Terms and Relationships 3 2.2 Other Document: OSHA Regulations, 29CFR, paragraphs 1910.1000 and 1910.12004
5. Apparatus 5.1 Gas Chromatograph--Any instrument having a flame ionization detector that can be operated at the conditions given in Table 1. The system should have sufficient sensitivity to obtain a minimum peak height response for 10 mg/kg n-butylbenzene of twice the height of the signal background noise. 5.2 Columns--The choice of column is based on resolution requirements. Any column may be used that is capable of resolving all significant impurities from isopropylbenzene and from the internal standard. The columns described in Table 1 have been used successfully. 5.3 Recorder--Electronic integration is recommended.
3. Summary of Test Method 3.1 A known amount of internal standard is added to a This test method is under the jurisdiction of ASTM Committee D-16 on Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of Subcommittee DI6.0H on Styrene, Ethylbenzene, and C9 and C~o Aromatic Hydrocarbons. Current edition approved July 15, 1993. Published September 1993. Originally published as D 3760 - 79. Last previous edition D 3760 - 79 (1984). 2 Annual Book of A S T M Standards, Vol 06.04. 3 Annual Book of A S T M Standards, Vol 14.02. 4 Available from Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402.
6. Reagents and Materials 6.1 Purity of Reagents--Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended 578
~ TABLE Detector Column: Tubing Stationary phase Solid support Film thickness Length, m Diameter, mm Temperatures: Injector, =C Detector, *C Oven: Initial, °C Time 1, rain Final, *C Rate, *C/min Time 2, min Carrier gas Flow rate, mL/min Split ratio Sample size, I~L
1
D 3760
Instrumental Parameters Column A
Column B
Flame Ionization
Flame Ionization
fused silica polyethylene glycol crosslinked 0.25 p. 50 0.32 mm ID
fused silica methyl silicone crosslinked 0.5 I~ 50 0.32 mm ID
275 300
275 300
60 10 175 10 10 hydrogen 1.0 100:1 1.0
35 10 275 5 0 helium 1.0 100:1 1.0
that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available: Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 6.1.1 Internal Standard--Normal Butylbenzene (nBB) is the recommended internal standard of choice. Other compounds may be found acceptable provided they meet the criteria as defined in 4.5 and 6.1. 6.2 Carrier Gas--Chromatographic grade helium or hydrogen is recommended. 6.3 Compressed Air--Chromatographic grade. 6.4 Hydrogen~High purity.
7. Hazards 7.1 Consult current OSHA regulations and suppliers' Material Safety Data Sheets on handling materials listed in this test method. 8. Sampling and Handling 8.1 Sample the material in accordance with Practice D 3437.
0.856 for nBB and 0.857 for cumene, the resulting nBB concentration will be 0.1000 weight %. 10.2 Inject into the gas chromatography an appropriate amount of sample as previously determined according to 6.1 and start the analysis. 10.3 Obtain a chromatograph and peak integration report. Figs. 1 and 2 illustrate a typical analysis of cumene for Columns A and B, respectively. 11. Calculations 11.1 Determine the area defined by each peak in the chromatogram. 11.2 Calculate the percent concentration of the total nonaromatics and each impurity as follows:
(A,XC9
C~ = ~
(i)
(A2)
where: Ci = concentration of component i, weight %, Ai = peak area of component i, A2 = peak area of nBB, C2 = concentration of nBB, weight %. 11.3 Calculate the total concentration of all impurities as follows: C, EC~ (2) where: Ct = total concentration of all impurities. 11.4 Calculate the purity of isopropylbenzene as follows: isopropylbenzene, weight % = 100.000 - C, (3) =
12. Report 12.1 Report the individual impurities to the nearest 0.0001%.
12.2 Report the purity of isopropylbenzene to the nearest 0.001 weight %.
13. Precision and Bias 13.1 Precision:
9. Preparation of Apparatus 9.1 Follow manufacturer's instructions for mounting and conditioning the column into the chromatograph and adjusting the instrument to the conditions described in Table 1 allowing sufficient time for the equipment to reach equilibrium. See Practices E 260 and E 355 for additional information on gas chromatography practices and terminology.
Concentration: Weight %
Repeatability
Benzene Ethylbenzene n-Propylbenzene t-Butylbenzene Alpha-methylstyrene
0.0063 0.0037 0.0175 0.0203 0.0045
0.00024 0.00016 0.00078 0.00085 0.00093
Nonaromatics
0.03 I0
0.003 I0
0.0012 99.9150
0.00041 0.00530
Ortho-Dilsopropylbenzene Cumene
13.1.1 Repeatability data is based on one laboratory's analysis of a single standard sample over a 40-day period. 13.1.2 Reproducibility will be determined. 13.2 Bias--Since there is no accepted reference material suitable for determining the bias for the procedure in this test method for measuring isopropylbenzene purity, bias has not been determined.
I0. Procedure I 0.1 Into a 100-mL volumetric flask, add I00 tiLt of nBB to 99.90 mL of cumene. Mix well. Assuming a density of s Reagent Chemicals, American Chemical Society Specoqcations, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Pc,ale, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD. t Editorially corrected.
14. Keywords 14.1 alpha methylstyrene; benzene; butylbenzene; cumene; ethylbenzene; isopropylbenzene; nonaromatic hydrocarbons; propylbenzene; analysis by gas chromatography 579
o 3z6o
CURENE ANALYSIS W DIPB Inst: 14 Ch: Trey J
:F - 0
0
~jCumene
,~ . n-P ropylbenzene
~., t-Butylbenzene
f ~ . , n-Butylbenzene I
4J m-Diisopropylbenzene Non aromatics
/\
v, Benzene
A
MX I s.Butylbenzene
'" 0,0
'
'
'
| 3,0
'
f
'
~
6.0
'
'
'
"
I 9.0
'
'
~" " ~ ' ' l ' ' ' ' ' ~ 1;~,0
'
v
|
,
t5.0
, ~,
',
"[ 18.0
,
,
r
f'~'l
E~.O
MINUTES
FIG. 1 Typical Chmmatogram using Conditions for Column A
580
'
24,0
'
'
{ 27.0
30.0
(~ D 3760 cumene analysts condition ¢2 ;[net: Ch; 0 Tray # 0
~F-O
t
Cumene
n-Propylbenzene
)
t.Butylbenzene m-Diisopropylbenzene
Benzene /& at 15.0 rain
'
30.0
32.0
'
'
I
34.0
'
'
'
'
I
'
36.0
i
,
~
I
i
3B.0
,
,
,
1
. . . .
40.0
I
42.0
'
' ' '
I ' ' 44.0
'
'
I
46.0
'
'
'
'
I ' 48.0
MINUTES FIG. 2
Typical C h r o m a t o g r a m using Conditions for Column B
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and ff not revised, either reepproved or withdrawn, Your commentsare invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful Gonsideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
581
L
' ~ ~ t 50.0
(~[~ Designation: D 3797 - 96 Standard Test Method for Analysis of o-Xylene by Gas Chromatography I This standard is issued under the fixed designation D 3797; the number immediately following the designation indicate~ the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (0 indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 This test method covers the analysis of normally occurring impurities in, and the purity of, o-xylene by gas chromatography. Impurities determined include nonaromatic hydrocarbons, benzene, toluene, p- and m-xylenes, cumene, styrene, and ethylbenzene. 1.2 This test method is applicable for impurities at concentrations from 0.001 to 2.000 % and for o-xylene purities of 98 % or higher. 1.3 The following applies to all specified limits in this standard: for purposes of determining conformance with this standard, an observed value or a calculated value shall be rounded off "to the nearest unit" in the last right-hand digit used in expressing the specification limit, in accordance with the rounding-off method of Practice E 29. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement, see Section 7. 2. Referenced Documents
2.1 A S T M Standards: D 3437 Practice for Sampling and Handling Liquid Cyclic Products 2
D 4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards 3 E 29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications4 E 260 Practice for Packed Column Gas Chromatograph# E 355 Practice for Gas Chromatography Terms and Relationships 4 E 15 l0 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs 4 2.2 Other Documents: OSHA Regulations, 29 CFR, paragraphs 1910.1000 and 1910.12005
3. Summary of Test Method 3.1 A known amount of internal standard is added to the sample. A gas chromatograph equipped with a flame ionization detector and a polar-fused silica capillary column is used for the analysis. The impurities are measured relative to the internal standard. To calculate o-Xylene purity subtract the impurities found from 100.00 %. 4. Significance and Use 4.1 This test method is suitable for setting specifications on o-xylene and for use as an internal quality control tool where o-xylene is used in a manufacturing process. It may be used in development or research work involving o-xylene. 4.2 Purity is commonly reported by subtracting the determined expected impurities from 100 %. Absolute purity cannot be determined if unknown impurities are present. 5. Apparatus 5.1 Gas ChromatographymAny gas chromatograph having a flame ionization detector and a splitter injector suitable for use with a fused-silica capillary column may be used, provided the system has sufficient sensitivity to obtain a minimum peak height response of 0.1 mV for 0.010 % internal standard when operated at the stated conditions. Background noise at these conditions is not to exceed 3 I~V. 5.2 Chromatographic Column, fused silica capillary, 60-m long, 0.32-ram inside diameter, internally coated to a 0.5-~tm thickness with a bonded (cross-finked) polyethylene glycol. Other columns may be used after it has been established that such column is capable of separating all major impurities and the internal standard from the o-xylene under operating conditions appropriate for the column. 5.3 Recorder, electronic integration with tangent capabilities (required). 5.4 Microsyringes, 10-ttL, and 50-ttL. 5.5 Volumetric Flask, 50-mL. 6. Reagents and Materials 6.1 Carrier Gas, hydrogen or helium, chromatographic grade. 6.2 Compressed Air, oil free. 6.3 Hydrogen, chromatographic grade. 6.4 Nitrogen, chromatographic grade. 6.5 Pure compounds for calibration shall include nnonane (Note l), toluene, styrene, ethylbenzene, p-xylene, m-xylene, o-xylene, isopropylbenzene, isooctane, (Note 2), n-octane (Note 2), n-undecane (Note 2), of a purity not less than 99 %. If the purity of the calibration compounds is less than 99 %, the concentration and identification of impurities must be known so that the composition of the final weighed
t This test method is under the jurisdiction of ASTM Committee D--16 on Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of Subcommittee DI6.0A on Benzene, Toluene, Xylenes, Cy¢lohexane, and Their Derivatives. Current edition approved Jan. 10, 1996. Published March 1996. Originally published as D 3797 - 79. Last previous edition D 3797 - 95. 2 Annual Book of ASTM Standards, Vol 06.04. 3 Annual Book of A S T M Standards, Vol 05.02. 4 Annual Book of ASTM Standards, Vol 14.02. 5 Available from Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402.
582
tl~) O 3797 TABLE 1
blends can be adjusted for presence of the impurities. NOTE l--n-nonane represents the nonaromaticin a sample. NOTE 2--Any of these compounds may be used as an internal standard provided it elutes free of contamination.
Instrument Parameters
Carder Carder gas flow rate at 1100C, mr./rain Detector Detector temperature, °C Injection port temperature, *C Hydrogen flow rate, mL/min
7. Hazards
Airflow rate, mL/mln Make-up gas Make-up gas flow rate, mL/min Split flow, ml../mln Column temperature program: Initial temperature, *C Initial time, rain Programming rate, *C/rain Final temperature, *C Chart speed, cm/min Sample size, IxL
7.1 Consult current OSHA regulations, local regulations, and supplier's Material Safety Data Sheets for all materials used in this test method. 8. Sampling
8.1 Guidelines for taking samples from bulk are given in Practice D 3437.
helium 1.2 flame ionization 240
230 30 275
nitrogen 23 150 70 24 20 210 1 0.6
9. Calibration
9.1 Prepare a synthetic mixture in accordance with Practice D 4307 from pure hydrocarbons with all of the aromatic compounds present in the sample to be analyzed containing approximately 98.0 weight % o-xylene and the expected significant impurities at their expected concentration. Suggested composition is given in weight percent, o-Xylene of a purity not less than 99 weight % must be used in preparing the calibration mixture. The pure material itself must be analyzed and corrections made in the composition of the calibration blend as required. Sample the material in accordance with Practice D 3437. o-xylene toluene p-xylene m-xylene ethylbenzene isopropyl benzene n-nonane
benzene styrene
manufacturer of the gas chromatograph and Practices E 355 and E 1510. 10.2 Fill a 50-mL volumetric flask to the mark with test specimen. With a microsyringe, add 30 ~tL of the standard. Mix well. Using a density of 0.692 for/so-octane and 0.880 for o-xylene, this solution will contain 0.0472 weight % internal standard. 10.3 Inject 0.6 IxL of solution into the gas chromatograph and obtain the chromatogram. A typical chromatogram is shown in Fig. 1.
98.25 % 0.2 % 0.2 % 0.4 % 6.2 % 0.3 % 0.2 % 0.2 % 0.05 %
11. Calculation 11.1 Measure the areas of all peaks, including the internal standard, except for the o-xylene peak. 11.2 Sum all the peaks eluting between the isooctane and toluene peaks. Identify this sum as nonaromatic hydrocarbons plus benzene. 11.3 Calculate the weight percent of the individual impurities, C i to the nearest 0.001% as follows:
9.2 Analyze the o-xylene used in preparing the calibration blend as described in 10.2 and 10.3. Calculate the purity of the stock o-xylene as shown in 11.3, using an assumed response factor of 1.00 for each impurity. This will verify that the o-xylene used in preparing this test method is 99 weight % or better. 9.3 Analyze the calibration blend as described in 10.3. 9.4 Calculate response factors as follows: R; =
c,
c,
--
IS (A~) A,(Rd
(2)
where: I S = internal standard, weight %, A i = area of impurity, R,~ = response factor for impurity, and A, = area of internal standard. 11.4 Use the response factor determined for n-nonane for all the nonaromatic hydrocarbon plus benzene peaks. 11.5 Calculate the purity of the o-xylene by subtracting the sum of the impurities from 100.00.
(1)
where: response factor for impurity relative to internal standard, A i =- area of impurity peak in calibration blend, A b = area of impurity in the stock o-xylene, c,= concentration of internal standard, weight %, area of internal standard peak in calibration blend, Asi Ash area of internal standard peak in stock o-xylene, and c,= concentration of impurity, weight, %. 9.5 Calculate response factors to the nearest 0.001. Ri =
12. Report 12.1 Report the following information: 12.1.1 The concentration of each impurity to the nearest 0.001 weight %, and 12.1.2 The purity of o-xylene to the nearest 0.01 weight %.
=
=
13. Intermediate Precision and Bias 6
13.1 P r e c i s i o n - - T h e following criteria should be used to
10. Procedure
10.1 Install the chromatograph column and establish stable instrument operation at the operating conditions shown in Table 1. Refer to instructions provided by the
e Supporting data are available at ASTM Headquarters. Request Research Report D 16 - 1019.
583
~
D 3797
4.765
5.298 6.289 7.128
2
8.152
3
11
9.
267 10.169
5,6,7
13.311 13.714
14.839 14.368 IS.esl
I0
PEAK IDENTIFICATIONS:
19.328
I 22.112
1. /so-octane 2. n-Nonane 3. Benzene 4. Toluene 5. Ethylbenzene 6. p-Xylene 7. m-Xylene 8. Cumene 9. o-Xylene 10. Styrene 11. Non-aromatics plus benzene
FIG. 1 TypicalChrematogram(SeeTable1)
584
8 9
({~ O 3797 TABLE 2
judge the acceptability (95 % probability level) of the results obtained by this test method. The criteria were derived from a round robin between nine laboratories. The data were run over two days using different operators. 13.1.1 Intermediate Precision formerly called Repeatability--Results in the same laboratory should not be considered suspect unless they differ by more than the amount shown in Table 2. 13.1.2 ReproducibilityDThe results submitted by two laboratories should not be considered suspect unless they differ by more than the amount shown in Table 2. 13.2 Bias--No statement is made about bias since no acceptable reference material and value are available.
Component Styrene Cumene m-Xylene p-Xylene Ethylbenzane Toluene Benzene Nonaromatlcs o-Xylene
Intermediate Precision
Concentration weight ~ 0.005 0.221 1.066 0.192 0.011 0.063 0.091 0.088 98.261
Intermediate PreoJston 0.001 0.014 0.058 0.039 0.001 0.004 0.005 0.026 0.10
14. Keywords 14.1 gas chromatography;
o-xylene;purity
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received a fair hearing you should make your view8 known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohockan, PA 19428.
585
Reproducibility 0.002 0.057 0.26 0.066 0.005 0.017 0.026 0.065 0.42
(1~
Designation: D 3798 - 96b
Standard Test Method for Analysis of p-Xylene by Gas Chromatography 1 This standard is issued under the fixed designation D 3798; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsiion (0 indicates an editorial change since the last revision or reapproval.
analyzed by a gas chromatograph equipped with a flame ionization detector (FID). The peak area of each impurity and the internal standard is measured. The amount of each impurity is calculated from the ratio of the peak area of the internal standard versus the peak area of the impurity. Purity by GC (the p-xylene content) is calculated by subtracting the sum of the impurities found from 100.00. Results are reported in weight percent.
1. Scope 1.1 This test method covers the determination of known hydrocarbon impurities in, and the purity ofp-xylene by gas chromatography (GC). It is generally meant for the analysis of p-xylene of 99 % or greater purity. Impurity concentrations that can be measured range from 0.001 to 1.000 weight 7o. 1.2 The following applies to all specified limits in this test method: for purposes of determining conformance with this test method, an observed value or a calculated value shall be rounded off 'to the nearest unit' in the right-hand digit used in expressing the specification limit, in accordance with the rounding-off method of Practice E 29. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement, see Section 8.
4. Significance and Use 4.1 This test method is suitable for setting specifications on p-xylene and for use as an internal quality control tool where p-xylene is produced or is used in a manufacturing process. It may also be used in development or research work involving p-xylene. It is generally appfied to determining those commonly occurring impurities such as nonaromatic hydrocarbons, benzene, toluene, ethylbenzene, m-xylene, o-xylene, and cumene (isopropylbenzene). 4.2 Purity is commonly reported by subtracting the determined expected impurities from 100.00. However, a gas chromatographic analysis cannot determine absolute purity if unknown components are contained within the material being examined. Refer to Specification D 5136 for deterraining other chemical and physical properties ofp-xylene.
2. Referenced Documents
2.1 ASTM Standards: D 3437 Practice for Sampling and Handling Liquid Cyclic Products2 D 5136 Specification for High Purity p-Xylene2 E 29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications3 E 260 Practice for Packed Column Gas Chromatography3 E 355 Practice for Gas Chromatography Terms and Relationships 3 E 691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method 3 E 1510 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs 3 2.2 Other Document: OSHA Regulations, 29 CFR, paragraphs 1910.1000 and 1910.12004
5. Interferences 5.1 The internal standard chosen must be sufficiently resolved from any impurity and the p-xylene peak. Refer to 7.4.1. 6. Apparatus 6.1 Gas Chromatograph--Any chromatograph having a flame ionization detector that can be operated at the conditions given in Table 1. The system should have sufficient sensitivity to obtain a minimum peak height response for a 0.001 weight % impurity twice the height of the signal background noise. 6.2 Columns--Different columns have been found satisfactory, depending on the purity of the p-xylene to be analyzed. 6.2.1 p-Xylene Range from 99.0 to 99.8 %--Both capillary and packed columns have been found satisfactory. The column must give satisfactory separation of the internal standard from p-xylene and the impurity peaks. Complete separation of ethylbenzene and m-xylene from p-xylene is difficult and can be considered adequate if the distance from the baseline to the valley between peaks is not greater than 50 % of the peak height of the impurity. Table 1 contains a description of two columns that have been found satisfactory. 6.2.2 p-Xylene Range 99.8 7o and Greater--Only capillary columns have been found satisfactory. Complete separation
3. Summary of Test Method 3.1 A known amount of an internal standard is added to a specimen of p-xylene. The prepared specimen is mixed and This test method is under the jurisdiction of ASTM Committee D-16 on Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of Subcommittee DI6.0A on Benzene, Toluene, Xylenes, Cyclohexane and Their Derivatives. Current edition approved Dec. 10, 1996. Published February 1997. Originally published as D 3798 - 79. Last previous edition D 3798 - 96a. 2 Annual Book of A S T M Standards, Vol 06.04. 3 Annual Book of A S T M Standards, Vol 14.02. Available from Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402.
586
(~ D 3798 TABLE 1
A
B
Column: Tubing Stationary phase
fused sfl=ce crosslinked
Concentration, weight % Solid support Mesh size Film thickness, [.t Length, m Inside diameter, mm Carrier gas: Flow rate, mL/min Split ratio
polyethylene glycol not applicable not applicable 0.25 50 0.32 helium 1.0 100:1
stainless steel diisodecylphthalate Bentone 34 A 3.5 %/3.5 % flux-calcined diatomite a 60 to 80 not applicable 6.1 3.2 helium 30 not applicable
200 200 60
200 200 60
n-undecane
n-octane
Temperature, °C: Inlet Dectector Column Intemal Standard
TABLE 2
Instrument Conditions for p-Xylene Analysis
,* The sole source of supply of the material known to the committee at this time is Bentone 34, available from National Lead Co. If you are aware of alternative suppliers, please provide this information to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, 1 which you may attend.
of ethylbenzene and m-xylene from p-xylene is difficult and can be considered adequate if the distance from the baseline to the valley between peaks is not greater than 50 % of the peak height of the impurity. It is important that tangential skimming is employed. Table I A contains a description of one column that has been found satisfactory. 6.3 RecordermElectronic integration is required. Tangent skimming capabilities are required because of the difficulty in fully separating impurities from p-xylene. 6.4 Microsyringe, 100-1xLcapacity. 6.5 VolumetricFlask, 100-mL capacity.
Component
p-Xylene (see 7.2.1) Toluene Ethylbenzene
m-Xylene o-Xylene Isopropylbenzene n-Nonane
Typical Calibration Blend
mL
Density A
Weight, g
Concentration, weight %
572.0 0.058 0.579 1.163 0.116 0.058 0.070
0.857 0.862 0.863 0.860 0.876 0.857 0.714
490.2 0.050 0.500 1.000 0.102 0.050 0.050
99.64 0.010 0.102 0.203 0.021 0.010 0.010
A Numbers are density in grams per millilitre at 25"C.
as indicated by gas chromatography. 7.3 Carrier GasnChromatographic-grade nitrogen, helium, or hydrogen have been found satisfactory for the p-xylene range from 99.0 to 99.8 %. However, only helium or hydrogen have been found satisfactory for the p-xylene range of 99.8 % and greater. 7.4 Pure Compounds for Calibration, shall include mxylene, o-xylene, toluene, ethylbenzene, isopropylbenzene (cumene), and n-nonane. The purity of all reagents should be 99 % or greater. If the purity is less than 99 %, the concentration and identification of impurities must be known so that the composition of the standard can be adjusted for the presence of the impurities. 7.4.1 Internal Standard--n-Undecane (NCI 1) is the recommended internal standard of choice for Conditions A and n-octane (NC8) for Conditions B in Table 1. However, other compounds may be found acceptable provided they meet the criteria as defined in Section 5 and 7.4.
8. Hazards 8.1 Consult current OSHA regulations, supplier's Material Safety Data Sheets, and local regulations for all materials used in this test method.
7. Reagents
7.1 Purity of Reagent--Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available. 5 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 7.2 High Purity p-Xylene (99.99 % or greater purity)-Most p-xylene is available commercially at a purity less than 99.9 weight %, but can be purified by recrystaUization. To prepare 2 qt of high-purity p-xylene, begin with approximately 1 gai of reagent-grade p-xylene and cool in an explosion-proof freezer at - 1 0 -4- 10*C until approximately I/2 to 3/4 of the p-xylene has frozen. This should require about 5 h. Remove the sample and decant the liquid portion. Allow the p-xylene to thaw and repeat the crystallization step on the remaining sample until the p-xylene is free of contamination
9. Sampling 9.1 Sample the material in accordance with Practice D 3437. 10. Preparation of Apparatus 10.1 The method used to prepare packed columns is not critical provided that the finished column produces the desired separation. 10.2 Follow the manufacturer's instructions for mounting and conditioning the column into the chromatograph and adjusting the instrument to the conditions described in Table 1. Allow sufficient time for the equipment to reach equilibrium. See Practices E 260, E 355, and E 1510 for additional information on gas chromatography practices and terminology. 11. Calibration 1 I. 1 Prepare synthetic mixtures ofp-xylene with representative impurities on a weight basis. Weigh each hydrocarbon impurity to the nearest 0.0001 g. Refer to Table 2 for an example of a typical calibration blend, n-Nonane will represent the nonaromatic fraction.
5 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Peele, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
587
~
D 3798
J|
N--X~
?
mmNCli
i2.44 ~
E-.SEICZ t5.49 ~ ~
O-
48
CIjUI~I
.
7.0
A
9.0
1t.0
13.0
15.0
17.0
lg.0
21.0
23.0
~.0
MINUTES
FIG. 1 p-XyleneAnalyMs IMng Conditlons ,4 In Table I
12. Procedure
11.2 Using the exact weight, or alternatively the exact volumes and densities (see Table 2), calculate the weight % coneentration for each impurity in each calibration blend of ! 1.1. 11.3 Into a 100-mL volumetric flask, add 100.0 pL of n-undecane to 99.90 mL of the calibration blend; mix well. Assuming a density of 0.861 g/mL for the p-xylene blend and 0.740 g/mL for NCI 1, the resulting NCI 1 concentration will be 0.086 weight %. 11.4 Inject the resulting solution from 11.3 into the chromatograph. A typical chromatogram is illustrated in Fig. I. 11.5 Determine the response factor for each impurity relative to NCI 1 by measuring the area under each peak and calculate as follows:
12.1 Fill 100-mL volumetric flask half full with sample. Pipet 100.0 pL of internal standard into a 100-mL volumetric flask and dilute to the mark with the sample to be analyzed. Mix well. 12.2 Depending upon the actual chromatograph's operating conditions, charge an appropriate amount of specimen into the instrument. 12.3 Measure the area of all peaks except p-xylene. Measurements on the specimen must be consistent with those made on the calibration blend. Sum and report the nonaromatic fraction as a total area. A poorly resolved peak, such as m-xylene will often require a tangent skim from the neighboring peak. Make consistent measurements on the specimen and calibration chromatograms for tangents or poorly resolved peaks. A typical chromatogram is shown in Fig. 1.
Re- (Cs)(A,) _
where: R i -- response factor for impurity i relative to the internal standard, Ai = peak area of impurity i, As -- peak area of the internal standard, Cs = concentration of the internal standard, weight %, and C~ = concentration of impurity i, as calculated in 11.3, weight %. 11.6 Calculate the response factors to the nearest 0.001.
13. Calculation
13.1 Calculate the amounts of each individual impurity. Total the concentration of all impurities. Calculate the p-xylene purity by the difference from 100.00. 13.2 Calculate the impurities as follows: 588
({~) D 3798 (A,)(R,) (C.) (A~) c,= ~c,
Intermediate Precision and Reproducibility for Internal Standard Where p-Xylene Range is from 99.0 to 99.8 %
TABLE 3
C,=
where: Ct = total concentration of all impurities, weight %. 13.3 Calculate the purity ofp-xylene, P, in weight percent as follows: P
=
1oo.oo
-
NOTE--This data was calculated after the removal of outUers using Practice E 891. Variation of the p-xylene purity was determined from the variation of the calculated total purity.
c,
14. Report 14.1 Report the following information: 14.1.1 Individual impurities to the nearest 0.001 weight %, 14.1.2 For concentrations of impurities less than 0.001 weight %, report as rr
,2 Z Z
_o _m o
W n"
9. Calculation 9.1 Record the final volume of water and sediment in each tube. If the difference between the two readings is greater than one subdivision on the centrifuge tube (see Table 1) or 0.025 m L for readings of 0.10 m L and below, the readings are inadmissible and the determination shall be repeated. 9.2 Express the sum of the two admissible readings as the percent by volume of water and sediment; report the results as shown in Table 2.
F-
~
E
A
T
A
B
I
L
I
T
Y
1
008
i
zo 007 0.06 ~0.O5 0.04 0 03 0 o2 001
I
0 0
0 01
1
I
I
I
I
I
0.02 0.03 0 04 0.05 0.06 0.07 AVERAGEWATER, PERCENT,BY DISTILLATION
I
0.08 0.085
FIG. X1.1 Basic Sediment and Water Precision for ASTM Test Method D 95 Distillation (Based on Seven laboratories)
February 9, 1979). Statistical tests showed that laboratory 5's data did not belong to the same population as the other data. (a) Laboratory 2's data were also suspect and did not appear to belong to the same population as the other data. However, it was learned that Laboratory 2's results were closest to actual levels of water added to the samples. There is, therefore, a dilemma on whether or not to reject Laboratory 2's data. As a compromise, precision was calculated with and without Laboratory 2's results. The following table lists the outliers rejected and the substituted values when Laboratory 2's results are retained: Laboratory
Sample
Rejected Value
Substituted Value
2 2 2 6 6
2 7 21 6 15
0.19 0.42 0.85 0.65 1.59, 1.44
0.06 0.20 0.61 0.85 0.922
S = A x ( I - e "M)
where: S = precision, = sample mean, and A and b are constants. was found to best fit the data. The values of the constants A and b were calculated by regression analysis of the linear logarithmic equation: log S = log A/log( 1 - e-t'R') XI.4.4.2 The standard deviation for repeatability for each sample was calculated from pair-wise (repeat pairs) variances pooled across the laboratories. The standard deviation for reproducibility was calculated from the variance of the mean values of each pair. This variance is equal to the sum of two variances, the variance aL2 due to differences between laboratories and the variance due to repeatability error az.2 divided by the number of replicates: a, 2 = a ) / n + az2(n = 2)
(b) With Laboratory 2's results omitted, only Laboratory 6's results listed above were rejected. XI.4.4 Calculation o f R e p e a t a b i l i t y a n d Reproducibility: X1.4.4.1 Repeatability and reproducibility were obtained by fitting curves of the appropriate precision of the results on each sample versus the mean value of each sample. An equation of the form: o 20
I
I
I
Using the data calculated above for each sample, the following values for the constants in Eq 1 were obtained:
I
l
~
n.-
~015
I
I
I
1
REPRODUCIBILITY
Z Z
o ~OlO
REPEATABILITY
LM n"
:~005 I,-
0 0
I 0 02
I I I I I I I I 0 04 0 . 0 6 0.08 0 10 0 12 O 14 0 . 1 6 0.18 AVERAGEWATER, PERCENT,BY CENTRIFUGE
FIG. X1.2 Basic Sediment and Water Precision for ASTM Test Method D 1796 Centrifuge (Based on Five laboratories)
614
tl~ D 4007 0,30
f
I
I
I
I
I
|
I
0 25
o 20 z
_o o 1 5 0 iii
" 010
O05~f
0 0
I
I
I
I
I
I
I
002
004
006
0.08
0.10
012
014
I 016
I 018
AVERAGE WATER, PERCENT, BY CENTRIFUGE
FIG. Xl.3
Basic Sediment and Water Precision for ASTM Test Method D 1796 Centrifuge (Based on Six Laboratories)
Distillation Method 7 Laboratories Repeatability Reproducibility
n o t p e r m i t a n y p a i r o f results to b e c o n s i d e r e d suspect. T h i s is b e c a u s e t h e p r e c i s i o n i n t e r v a l exceeds t w i c e t h e m e a n value. F o r e x a m p l e , in Fig. X 1.1, t h e r e p e a t a b i l i t y at 0.03 % water is 0 . 0 6 1 % . It is not possible to observe a difference of
Constant
b A
47.41 47.41 0.2883 0.0380 Centrifuge Method 6 Laboratories Repeatability Reproducibility
more than 0.06 and still average 0.03. Thus, a pair of observations of 0.00 and 0.06 are acceptable. X1.4.4.6 Analyses of variance were performed on the data without regard to any functionality between water level and precision. The following repeatabilities and reproducibilities were found:
Constant
b A
11.23 0.0441
11.23 0.1043
Method
5 Laboratories Repeatabihty Reproducibility
Distillation (seven laboratories)
Constant
b A
17.87 0.0437
Centrifuge (six laboratories)
17.87 0.0658
TABLE Xl.7
The values of precision calculated by Eq 1 were multiplied by 2.828 (2 x ~ ) to convert them to the ASTM-defined repeatability and reproducibility. X1.4.4.3 The curves of repeatability and reproducibility for the distillation method in the range 0 to 0.09 % water are shown in Fig. XI.I. These data are also tabulated in Table XI.7. The curves for the centrifuge method in the range 0 to 0.2 % water are shown in Fig. X1.2 (five-laboratory case) and Fig. XI.3 (six-laboratory case). XI.4.4.4 For higher levels of water the limiting repeatabilities and reproducibilities are: Method Distillation Centrifuge (five-laboratorycase) Centrifuge (six-laboratory case) Method Distillation Centrifuge (five-laboratorycase) Centrifuge (six-laboratory case)
Repeat-
% Water 0.000 0.005 0.010 0.015 0.020 0.025 0.030 0.035 0.040 0.045 0.050 0.055 0.080 0.065 0.070 0.075 0.080 0.085 0.090 0.095 0.100 0.105 0.110 0.115 0.120 0.125 0.130
Repeatability Range of Concentration, % Value, % _>.085 0.08 _>.155 0.12 ->.235 0.12 Reproducibility Range of Concentration, % Value, % ->0.085 0.105 ->0.325 0.19 ->0.315 0.29
X1.4.4.5 It should be pointed out that at the lowest water levels, the precision "statements" for some of the analyses do
615
ability 0.08
0.12
Reproducibility 0. I I
0.28
ASTM Precision Intervals: ASTM D 95 (7 Laboratodes)
Repeatability 0.000 0.017 0.030 0.041 0.049 0.056 0.061 0.065 0.068 0.071 0.073 0.074 0.075 0.076 0.077 0.078 0.078 0.079 0.079 0.079 0.079 0.079 0.080 0.080 0.080 0.080 0.080
Reproducibility 0.000 0.023 0.041 0.055 0.066 0.075 0.082 0.087 0.091 0.095 0.097 0.1 O0 0.101 0.103 0.1 04 0.1 04 0.105 0.106 0.106 0.106 0.107 0.107 0.107 0.107 0.107 0.107 0.107
% Water 0.000 0.005 0.010 0.015 0.020 0.025 0.030 0.035 0.040 0.045 0.050 0.055 0.060 0.065 0.070 0.075 0.080 0.065 0.090 0.095 0.100 0.105 0.110 0.115 0.120 0.125 0.130
I~) D 4007 These values are almost exactly the same as the limiting values obtained by curve fitting.
(c) Above 0.1% water, the repeatability is 0.08 and the reproducibility is 0.11.
X 1.5.1.2 Centrifuge Method: (a) Repeatability is related to water content up to about 0.2 % water and reproducibility up to about 0.3 %. (b) In the range 0.01 to 0.2, repeatability varies from 0.01 to 0.11 and reproducibility in the range 0.02 to 0.3 from 0.03 to 0.28. X1.5.2 It is recommended that: XI.5.2.1 Precision should be presented as a graph in the range where precision varies with water content. X1.5.2.2 Precision should be presented as a statement where the precision is constant. X1.5.3 In view of what appears to be lower bias and better precision, Test Method D 95 should be the specified method for use in critical situations.
X1.5 Conclusions and Recommendations XI.5.1 Data obtained in seven-laboratory round robin on measurement of basic sediment and water by the distillation test method (D 95) and the centrifuge test method (D 1796) in 21 crude oil samples were examined. The conclusions are: X1.5.1.1 Distillation Method: (a) Precision is related to water content up to about 0.08 % water. (b) In the range from 0.01 to 0.08, repeatability varies from 0.020 to 0.078 and reproducibility from 0.041 to 0.105.
The American Society for Testing and Materials takes no position respecting the vahdlty of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determmation of the vahdtty of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is sublect to revision at any time by the responsible technical committee and must be reviewed every hvo years and tf not revised, either reapproved or withdrawn Your comments are mvtted either for rewslon of this standard or for additional standards and should be addressed to ASTM Headquarters Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend If you feel that ,/our comments have not received a lair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Herbor Drive, West Conshohocken, PA 19428
616
q~l~ Designation:D 4045 - 96
An American National Standard
Standard Test Method for Sulfur in Petroleum Products by Hydrogenolysis and Rateometric Colorimetry 1 This standard is issued under the fixed designation D 4045; the number immediately following the designation indicates the year of original adoption or, in the ease of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 This test method covers the determination of sulfur in petroleum products in the range from 0.02 to 10.00 mg/kg. 1.2 The method may be extended to higher concentration by dilution. 1.3 The method is applicable to liquids whose boiling points are between 30 to 371"C (86 and 700*F). Materials that can be analyzed include naphtha, kerosine, alcohol, steam condensate, various distillates, jet fuel, benzene, and toluene. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards: D 1193 Specification for Reagent Water 2
3. Summary of Test Method
3.1 The sample is injected at a constant rate into a flowing hydrogen stream in a hydrogenolysis apparatus. The sample and hydrogen are pyrolyzed at a temperature of 1300"C or above, to convert sulfur compounds to hydrogen sulfide (H2S). Readout is by the rateometric detection of the colorimetric reaction of H2S with lead acetate. Condensable components are converted to gaseous products such as methane during hydrogenolysis.
4. Significance and Use
4. I In many petroleum refining processes, low levels of sulfur in feed stocks may poison expensive catalysts. This method can be used to monitor the amount of sulfur in such petroleum fractions. 4.2 This method may also be used as a quality-control tool for sulfur determination in finished products. This test method is under the jurisidiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee I)02.03 on Elemental Analysis. Current edition approved Nov. 10, 1996. Published January 1997. Originally published as D 4045 - 87. Last previous edition D 4045 - 92 El. 2 Annual Book of ASTM Standards. Vol I 1.01.
617
5. Apparatus a,4 5.1 Pyrolysis Furnace--A furnace that can provide an adjustable temperature of 900 to 1400"C in a 5-mm inside diameter or larger tube is required to pyrolyze the sample. The furnace entry temperature must allow insertion of the hypodermic tip to a depth at which the temperature is 550"C to provide sample vaporation at the injection syringe tip. This temperature must be above the boiling point of the sample and of the sulfur compounds in the sample (see Fig. 1). The pyrolyzer tube may be of quartz; however, the lifetime is limited above 1250"C. Ceramic may be used at any temperature. 5.2 Rateometric H:,S Readout--Hydrogenolysis products contain H2S in proportion to sulfur in the sample. The H2S is measured by measuring rate of change of reflectance caused by darkening when lead sulfide is formed. Rateometric electronics, adapted to provide a first derivative output, allows sufficient sensitivity to measure below 0.1 mg/L (see Fig. 2). 5.3 Hypodermic Syringe--A hypodermic having a needle long enough to reach the 5500C zone is required. A side port is convenient for vacuum filling and for flushing the syringe. A 100-1xL syringe is satisfactory for injection rates down to 3 I~L/min and a 25-~tL syringe for lower rates. NOTE h Warning--Exercise caution as hypodermicscan cause accidental injury.
5.4 Syringe Injection Drive--The drive must provide uniform, continuous sample injections. Variation in drive injection rate caused by mechanical irregularities of gears will cause noise. The adjustable drive must be capable of injection from 6 ~tL/min to 0.06 ~tL/min over a 6-min interval. 5.5 Recorder--A chart recorder with 10-V full scale and 10 000-[2 input or greater is required having a chart speed of 0.2 to 1 in./min (approximately 0.5 to 3 cm/min). An attenuator can be used for more sensitive recorders. 5.6 Thermocouple--A thermocouple suitable for use at 500 to 1400"C, 250 mm long with readout is required. Type K, 1/16-in. (l.6-mm) diameter, Type 316 stainless steel sheath is suitable. 3 The apparatus described in 5. I to 5.4 inclusive is similar in specification to the equipment available from Houston Atlas, Inc., 22001 North Park Dr., Kingswood, TX 77339-3804. For further information see Drushel, H. V., "Trace Sulfur Determination Petroleum Fractions," Analytical Chemistry, Vol 50, 1978, p. 76. 4 Houston Atlas, Inc. is the sole source of supply of the apparatus known to the committee at this time. If you are aware of alternative suppliers, please provide this information to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, I which you may attend.
~) DISPOSABLE CERAMIC OR QUARTZREACTION TUBE BALSTON
SAMPLE TO825RFOR TOTALSULFUR READOUT
D 4045
INJECTIONOFLIQUIO (n:m CONTROLLED RATE SYRINGE
PYROLYZER®
~ ' q
HU"IOIFIER / II~
GAS WASHBOTTLE ~ ~
~ L ~ L
~l 1N|
kNI INi
il/ CARRIERH2 NOTE~Thehumidifiergas wash bottle is optional.
FIG. 1 HydrogenolysisFlow Diagram
UNGSTENLA4-SAMPLEFROM PYROLYZER®
,0c,,sINGLcJ
:D
(::=
FINE ,ocus RALANCINg 1l:Ng
F TOR
WINDOW
FIG. 2 PhotorateometryH=S Readout 6. Reagents and Materials
6.1 Purity of Reagents--Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where such specifications are available, s Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without s Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Peele, Dorset, U.K., and the United Stales Pharmacopeia and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
618
lessening the accuracy of the determination. 6.2 Purity of Water--Unless otherwise indicated, references to water shall be understood to mean Type II reagent grade water conforming to Specification D 1193. 6.3 Sensing Tape--Lead acetate impregnated paper of chromatographic quality shall be used. NOTE 2: Warning--Lead is a cumulative poison. 6.4 Hydrogen--As no commercial grade of hydrogen has a sulfur specification sufficiently low, each new source of supply must be tested. A change in the zero base line of 5 % of full scale from no flow to full flow indicates impure hydrogen. NOTE 3: Wm~ing--Extremely flammable gas under pressure. NOTE 4: Warning, Precution--Hydrogen is a flammable gas. Test all flow systems for leaks and purge with inert gas before introducing hydrogen and after removing hydrogen. Keep all flow systems as small in volume as practical and provide protective screening for containers other than sample flow lines. Dispose of exhaust gases in a fume hood or by vacuuming to a safe area. If gas cylinders are used handle carefully as rupture of the valve or cylinder is dangerous. 6.5 Reference Standards: 6.5. l Isooctane--ASTM Knock Test Reference Fuel. 6 NOTE 5: Warning--Extremely flammable. NOTE 6--1scociane is to be used as a solvent for sulfur compounds. Test each new lot for sulfur by this procedure as specifications are not rigorous enough for this application, n-heptane or equivalent material may be used. 6.6 Acetic Acid Solution--Mix glacial acetic acid 1 part by volume to 19 parts distilled water. NOTE 7: Warning--Corrosive. 6.7 Di-n-Butyl Sulfide (CH3CH2CH2CH2)2S) is used to prepare standards. Equivalent sulfur compound may be used if care is exercised to prevent more volatile compounds from evaporating during preparation or use of standards. 6.8 Helium or Nitrogen Purge Gas NOTE 8: Warning--Compressedgas under high pressure. Availablefrom PhillipsPetroleumCo., P.O. DrawerO, Borger,TX 79071.
~[~) O 4045 7. Calibration Standard 7.1 Prepare a reference standard-solution or solutions of strength near that expected in the unknown. Measurements can be made by weight or by volume for carder liquid. 7.2 Units of sulfur in milligrams per litre of sample are preferred as this is independent of the density of the carder liquid. The following equation is used to calculate the volume of solvent required to dissolve a precise weight of sulfur compound, of known composition and purity to prepare a liquid standard: z ffi
x d × e x 10 6 I(a)
or alternatively:
a ffi ( b x d x e x 106)/(z)
sulfur compounds. Volumetrically dilute stock to prepare low-level standards. 8. Preparation of Apparatus 8.1 Turn on the furnace with temperature controls at minimum. Gradually increase furnace control over a 3-h period to approximately 13000C to minimize thermal shock. Reverse the procedure when preparing for long-term storage. For shutdown at night and weekends reduce temperature to about 900°C but do not turn off the furnace. Furnace and quartz tubing life are extended by not cooling to room temperature. 8.2 Connect all tubing and fill prehumidifier outside the cabinet with distilled water if this apparatus is being used, and final humidifier inside the cabinet with 5 % by volume acetic acid solution. Purge with inert gas then close valve. Check all connections with soap solution and repair any leaks. Set hydrogen flow at 200 mL/min and allow temperature to stabilize. (Warning--see Note 3). Make final temperature adjustment to 1315 + 15"C. Use a standard thermocouple to verify temperature by inserting through a septum with hydrogen flowing at the rate noted above. Determine depth of insertion required and always insert the hypodermic tip to the 550"C point (see 8.6). NOTE 9: Warning--The use of a humidifiergas wash bottle filled with approximately 250 mL of distilled water is a potential safety hazard, as hydrogenpressure may build up inside the container. The user of the test method should take appropriate safety measures to prevent an accidentalinjury,if the humidifiergas wash bottle is used in the analysis.
(1)
(2)
where: a = desired concentration of sulfur, mg/L, of the standard solution of z millilitre of volume, b = molecular weight of sulfur: 32.06, c = molecular weight of the sulfur compound to be used to prepare the standard. d = mass of the sulfur compound used to prepare the standard, g, e = purity of sulfur c o m p o u n d expressed as a decimal, and z -- millilitres of standard solution required to give the desired concentration a.
Example: Calculate the volume of sulfur free isooctane with volume of sulfur compound necessary to dissolve 0.5013 g of 98 % by weight di-n-butyl sulfide to obtain a standard containing 1000 mg/L of sulfur in a solution. a = 1000 mg/L b = 32.06 c = 146.29 di-n-butyl sulfide (CH3CH2CH2CH2)2S d = 0.5013 g e ffi 0.98 [32.06/146.29 x 0.5013 x 0.98 x 106 z -ffi 107.66 mL 1000
8.3 Prepare the sample injection drive. Check to be sure desired injection rate is obtained at various settings. Verify that erratic pulses of fast drive do not occur when the drive range is switched. Pulses of high sample flow above 15 ~tL/min will cause carboning and spurious readings. 8.4 Install sensing tape and turn H2S readout analyzer on. 8.5 Connect the recorder and adjust the zero to desired position with hydrogen flowing. 8.6 Fill syringe with blank reference standard solution, typically isooctane, insert the needle through the septum to the 550°C temperature zone and clamp to the syringe drive. At high temperature the hot needle may absorb sulfur and at lower temperature heavy compounds may not evaporate. Set the syringe drive rate desired, normally 6 ttL/min, maximum with 200 mL/min hydrogen flow. Drive rate may be increased for increased sensitivity up to the point at which carbon is formed. (Hydrogen flow at 500 mL/min allows injection of 15 ttL/min; however, dibenzothiophene conversion will be low.)
Isooctane is added to bring the solution to a total volume of 107.66 mL. When results are to be reported in mass of parts per million mg/kg, the conversion from milligrams per litre should be done as the last step in the calculations. 7.3 To prepare a sulfur standard with a sulfur concentration of I000 mg/L as previously described, obtain a clean 125-mL glass container, a 100-mL flask, and a 20-mL graduated glass pipet. Rinse each thoroughly with isooctane (2,2,4-trimethylpentane). (Warning--see Note 3). Pour approximately 90 mL of isooctane into the 100-mL flask. Weigh approximately 0.5 g of di-n-butyl sulfide directly into the flask and record the mass added, to +50 ttg. Add additional isooctane to the flask to 100 mL. Transfer the mixture to the 125-mL container and add isooctane equal to the difference of z minus 100 mL. Keep containers closed as much as possible. Do not open containers of pure sulfur compound in the vicinity of sulfur free stocks or low-level standards. Evaporation from containers of pure sulfur compounds can contaminate other nearby liquids. This is particularly troublesome when working below I mg/L near volatile
9. Calibration and Standardization
9.1 With hydrogen flow at 200 mL/min, advance new tape and note baseline. Adjust the offset up scale about 5 % to be clear of the recorder stops. Record the stable reading average value as the zero sulfur reference and record as Rb in 11. I. There will be essentially no difference in reading with or without hydrogen flow and with or without blank injection, if blank and hydrogen have no sulfur. 9.2 Advance the tape and inject a reference material with a sulfur concentration near that expected in the unknown. Aider about 4 rain injection time adjust the recorder span for 619
~
D 4045
approximately 90 % of scale. Record the average reading as Rstd in I0.I.
apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following values only in one case in twenty (see Table 1). Repeatability = 0.16 VfX where X -- average value of two results, mg/kg. 12.1.2 Reproducibility--The difference between two single and independent results obtained by different operators working in different laboratories on identical test material would, in the long run, exceed the following values only in one case in twenty (see Table 1). Reproducibility = 0.26 ,fX NOTE 10---One laboratory conducted a statistical evaluation by analyzing the same sample (with a nominal sulfur concentration of 0.2 ppm), using multiple technicians and the same instrumentation, with and without the humidifier gas wash bottle installed, and determined that results were statistically equivalent for both precision and accuracy at the 95 % confidence interval. Results of the statistical evaluation are available from ASTM Headquarters. Request RR:D02-1405.
10. Procedure 10.1 Advance the tape and inject the unknown sample. After a stable reading is obtained record this average value as Rsin 11.1. 10.2 Proceed with additional samples. Every 2 h or as needed, verify blank and span values. 10.3 To measure sulfur below I rag/L, inject the sample at the maximum rate, normally 6 ttL/min, that does not form carbon or gums to obtain the best signal to noise ratio. Samples above I mg/L require proportionally lower injection rates or span adjustment. A sharp fall in response at high sulfur levels indicates color saturation o f the tape, which can be prevented by slower injection rates. 11. Calculations and Report 1 1.1 Calculate the concentration of the sulfur in the sample as follows: S, mg/L = C ~ x (R, - R b ) / ( R ~ o - Rb)
(3)
where: Cstd = concentration of sulfur in the standard, rag/L, Rb = response for blank run using no sample or for solvent known to be sulfur-free, R, = response for unknown sample, and R,td = response for standard reference material. I 1.2 Report mass of parts per million of sulfur as follows: S, ppm = (mg/L)/(density) ffi mg/kg (4) since density of sample is in grams per cubic centimetres. 12. Precision and Bias
12.1 The precision of this test method as obtained by statistical analysis of interlaboratory test results is as follows: 12. I. 1 Repeatability----The difference between successive test results obtained by the same operator with the same
12.2 Bias--The bias of this test method cannot be determined since an appropriate standard reference material containing trace sulfur levels in petroleum products is not available. 13. Keywords 13.1 rateometric colorimetry; sulfur
TABLE 1 Repeatabilityand Reproducibility Average value mg/kg of two
Repeatability,
Reprodudblllty,
resats (x)
mo/kg
n~/kg
0.02 0.10 0.50 1.50 2.50 10.00
0.02 0.05 0.11 0.16 0.25 0.50
0.04 0.08 0.18 0.26 0.41 0.82
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned In this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of Infringement of such rights, are entirely their own responsibility. This standard Is subject to revision at any time by the responsible technical committee and must be reviewed every five years and # not revised, althar reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received s fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohockan, PA 19428.
620
Designation: D 4052 - 96
An Arnedcan National Standard
Designation: 365/84(86) ~ . i.i I ~ n H I M
Standard Test Method for Density and Relative Density of Liquids by Digital Density Meter I This standard is issued under the fixed designation D 4052; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epdlon (~) indicates an editorial change since the last revision or reapproval.
This method was adopted as a joint ASTM-IP standard in 1984.
1. Scope 1.1 This test method covers the determination of the density or relative density of petroleum distillates and viscous oils that can be handled in a normal fashion as liquids at test temperatures between 15 and 35°C. Its application is restricted to liquids with vapor pressures below 600 mm Hg (80 kPa) and viscosities below about 15 000 cSt (mm2/s) at the temperature of test. 1.2 This test method should not be applied to samples so dark in color that the absence of air bubbles in the sample cell cannot be established with certainty. For the determination of density in crude oil samples use Test Method D 5002. 1.3 The accepted units of measure for density are grams per miUilitre or kilograms per cubic metre. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Notes 1 and 2. 2. Referenced Document
3.1.1 density--mass per unit volume at a specified temperature. 3.1.2 relative density.--the ratio of the density of a material at a stated temperature to the density of water at a stated temperature. 4. Summary of Test Method 4.1 A small volume (approximately 0.7 mL) of liquid sample is introduced into an oscillating sample tube and the change in oscillating frequency caused by the change in the mass of the tube is used in conjunction with calibration data to determine the density of the sample. 5. Significance and Use 5.1 Density is a fundamental physical property that can be used in conjunction with other properties to characterize both the light and heavy fractions of petroleum and petroleum products. 5.2 Determination of the density or relative density of petroleum and its products is necessary for the conversion of measured volumes to volumes at the standard temperature of 150C.
2.1 A S T M Standard:
6. Apparatus 6.1 Digital Density AnalyzernA digital analyzer consisting of a U-shaped, oscillating sample tube and a system for electronic excitation, frequency counting, and display. The analyzer must accommodate the accurate measurement of the sample temperature during measurement or must control the sample temperature as described in 6.2. The instrument shall be capable of meeting the precision requirements described in this test method. 6.2 Circulating Constant-Temperature Bath, (optional) capable of maintaining the temperature of the circulating liquid constant to +0.05"C in the desired range. Temperature control can be maintained as part of the density analyzer instrument package. 6.3 Syringes, at least 2 mL in volume with a tip or an adapter tip that will fit the opening of the oscillating tube. 6.4 Flow-Through or Pressure Adapter, for use as an alternative means of introducing the sample into the density analyzer either by a pump or by vacuum. 6.5 Thermometer, calibrated and graduated to 0. I'C, and a thermometer holder that can be attached to the instrument for setting and observing the test temperature. In calibrating
D 1193 Specification for Reagent Water2 D 1250 Guide for Petroleum Measurement Tables3 D4057 Practice for Manual Sampling of Petroleum and Petroleum Products4 D 4177 Practice for Automatic Sampling of Petroleum and Petroleum Products4 D4377 Test Method for Water in Crude Oils by Potentiometric Karl Fischer Titration4 D 5002 Test Method for Density and Relative Density of Crude Oils by Digital Density Analyzer5 3. Terminology 3.1 Definitions: This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.04 on Hydrocarbon Analysis. Current edition approved Apr. 10, 1996. Published June 1996. Originally published as D 4052 - 81. Last previous edition D 4052 - 95. 2 Annual Book of A S T M Standards, Vol 1 !.01. 3 Annual Book of A S T M Standards, Vol 05.01. 4 Annual Book of A S T M Standards, Vol 05.02. Annual Book of A S T M Standards, Vol 05.03.
621
([~ D 4052 bath following the manufacturer's instructions. Adjust the bath or internal temperature control so that the desired test temperature is established and maintained in the sample compartment of the analyzer. Calibrate the instrument at the same temperature at which the density of the sample is to be measured. NOTE 3: Caution--Precise setting and control of the test temperature in the sample tube is extremely important. An error of 0. I'C can result in a change in density of one in the fourth decimal.
the thermometer, the ice point and bore connections should be estimated to the nearest 0.05"C. 7. Reagents and Materials 7.1 Purity of Reagents--Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available. 6 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 7.2 Purity of Water--Unless otherwise indicated, references to water shall be understood to mean reagent water as defined by Type II of Specification D 1193. 7.3 Water, redistilled, freshly boiled and cooled reagent water for use as a primary calibration standard. 7.4 Petroleum Naphtha, 7 for flushing viscous petroleum samples from the sample tube. NOTS l--Extremely flammable. 7.5 Acetone, for flushing and drying the sample tube. NOT~ 2: Warning--Extremely flammable. 7.6 Dry Air--for blowing the oscillator tube. 8. Sampling, Test Specimens, and Test Units 8.1 Sampling is defined as all the steps required to obtain an aliquot of the contents of any pipe, tank, or other system, and to place the sample into the laboratory test container. The laboratory test container and sample volume shall be of sufficient capacity to mix the sample and obtain a homogeneous sample for analysis. 8.2 Laboratory Sample--Use only representative samples obtained as specified in Practices D 4057 or D 4177 for this test method. 8.3 Test Specirnen--A portion or volume of sample obtained from the laboratory sample and delivered to the density analyzer sample tube. The test specimen is obtained as follows: 8.3.1 Mix the sample if required to homogenize. The mixing may be accomplished as described in PracticeD 4177 (Section I I) or Test Method D 4377 (A.I). Mixing at room temperature in an open container can result in the loss of volatilematerial,so mixing in closed, pressurized containers or at sub-ambient temperatures is recommended. 8.3.2 Draw the test specimen from a properly mixed laboratory sample using an appropriate syringe.Alternatively,if the proper density analyzer attachments and connecting tubes are used then the test specimen can be delivered directlyto the analyzer'ssample tube from the mixing container, 9. Preparation of Apparatus 9.1 Set up the density analyzer and constant temperature Reagent Chemicals. American Chemical Society Spec~cations, American Cl~mic~ Society, Washington, De. For suggesliom on the testing of reagen~ not listod by tim Ammiean Chemical So~e~J, ~ Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dor~t, O.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Roekville, MD. ":Suitable solvent naphthas are marketed under various dedgnafiom such as "Petroleum Ether," "Ligtoine," or "Precipitation Naphtha."
622
10. Calibration of Apparatus 10.1 Calibrate the instrument when first set up and whenever the test temperature is changed. Thereafter, conduct calibration checks at weekly intervals during routine operation. 10.2 Initial calibration, or calibration after a change in test temperature, necessitates calculation of the values of the constants A and B from the periods of oscillation (T) observed when the sample cell contains air and redistilled, freshly boiled and cooled reagent water. Other calibrating materials such as n-nonane, n-tridecane, cyclohexane, and n-hexadecane (for high temperature applications) can also be used as appropriate. 10.2.1 While monitoring the oscillator period, T, flush the sample tube with petroleum naphtha, followed with an acetone flush and dry with dry air. Contaminated or humid air can affect the calibration. When these conditions exist in the laboratory, pass the air used for calibration through a suitable purification and drying train. In addition, the inlet and outlet ports for the U-tube must be plugged during measurement of the calibration air to prevent ingress of moist air. 10.2.2 Allow the dry air in the U-tube to come to thermal equilibrium with the test temperature and record the T-value for air. 10.2.3 Introduce a small volume (about 0.7 mL) of redistilled, freshly boiled and cooled reagent water into the sample tube from the bottom opening using a suitable syringe. The test portion must be homogeneous and free of even the smallest air or gas bubbles. The sample tube does not have to be completely full as long as the liquid meniscus is beyond the suspension point. Allow the display to reach a steady reading and record the T-value for water. 10.2.4 Calculate the density of air at the temperature of test using the following equation: d,, g/mE = 0.001293[273.15/T][P/760] (1) where: T = temperature, K, and P ffi barometric pressure, torr. 10.2.5 Determine the density of water at the temperature of test by reference to Table 1. 10.2.6 Using the observed T-values and the reference values for water and air, calculate the values of the Constants A and B using the following equations: A = [T~ - Ta2l/tdw - dol (2) B == Ta 2 - (A × do) (3) where: Tw = observed period of oscillation for cell containing water, T. = observed period of oscillation for cell containing air, dw = density of water at test temperature, and
~)
D 4052
da = density of air at test temperature. Alternatively, use the T and d values for the other reference liquid if one is used. 10.2.7 If the instrument is equipped to calculate density from the constants A and B and the observed T-value from the sample, then enter the constants in the instrument memory in accordance with the manufacturer's instructions. 10.2.8 Check the calibration and adjust if needed by performing the routine calibration check described in 10.3. 10.2.9 To calibrate the instrument to display relative density, that is, the density of the sample at a given temperature referred to the density of water at the same temperature, follow sections 10.2.1 through 10.2.7, but substitute 1.000 for d~ in performing the calculations described in 10.2.6. 10.3 Weekly calibration adjustments to constants A and B can be made if required, without repeating the calculation procedure. NOTE 4---The need for a change in calibration is generally attributable to deposits in the sample tube that are not removed by the routine
flushingprocedure. Althoughthis conditioncan be compensatedfor by adjusting A and B, it is good practice to clean the tube with warm chromic acid solution (Warning---Causes severe burns. A l'CCogniT~J carcinogen.) whenever a major adjustment is required. Chromic acid solution is the most effective cleaning agent; however, surfactant cleaning fluidshave also been used successfully. 10.3.1 Flush and dry the sample tube as described in 9.2.1 and allow the display to reach a steady reading. If the display does not exhibit the correct density for air at the temperature of test, repeat the cleaning procedure or adjust the value of constant B commencing with the last decimal place until the correct density is displayed. 10.3.2 If adjustment to constant B was necessary in 10.3.1 then continue the recalibration by introducing redistilled, freshly boiled and cooled reagent water into the sample tube as described in 10.2.3 and allow the display to reach a steady reading. If the instrument has been calibrated to display the density, adjust the reading to the correct value for water at the test temperature (Table 1) by changing the value of constant A, commencing with the last decimal place. If the instrument has been calibrated to display the relative density, adjust the reading to the value 1.0000.
and water. The settingchosen wouldthen be dependentupon whetherit was approached from a higher or lower value. The setting selected by this method could have the effect of altering the fourth place of the reading obtainedfor a sample. 10.4 Some analyzer models are designed to display the measured period of oscillation only (T-values) and their calibration requires the determination of an instrument constant K, which must be used to calculate the density or relative density from the observed data. 10.4.1 Flush and dry the sample tube as described in 10.2.1 and allow the display to reach a steady reading. Record the T-value for air. 10.4.2 Introduce redistilled, freshly boiled and cooled reagent water into the sample tube as described in 10.2.3, allow the display to reach a steady reading and record the T-value for water. 10.4.3 Using the observed T-values and the reference values for water and air (10.2.4 and 10.2.5), calculate the instrument constant K using the following equations: For density: KI = [ # w - aa]/[ r 2 - Ta2]
For relative density: K2 = [1.0000 - aa]/[T 2 - Ta2]
11. Procedure 11.1 Introduce a small amount (about 0.7 mL) of sample into the dean, dry sample tube of the instrument using a suitable syringe. 11.2 The sample can also be introduced by siphoning. Plug the external TFE-fluorocarbon capillary tube into the lower entry port of the sample tube. Immerse the other end of the capillary in the sample and apply suction to the upper entry port using a syringe or vacuum line until the sample tube is properly filled. 11.3 Turn on the illumination fight and examine the sample tube carefully. Make sure that no bubbles are trapped in the tube, and that it is filled to just beyond the suspension point on the right-hand side. The sample must be homogeneous and free of even the smallest bubbles.
TABLE 1 Densityof WaterA
NOTE 6--If the sample is too dark in color to determine the absence
of bubbles with certainty,the density cannot be measured within the stated precision limitsof Section 14. 11.4 Turn the illumination light off immediately after sample introduction, because the heat generated can affect the measurement temperature. 11.5 After the instrument displays a steady reading to four significant figures for density and five for T-values, indicating that temperature equilibrium has been reached, record the density or T-value.
Temperature, Density, Temperature, Danslty, Temperature, Density, *C g/mL *C g/mL *C g/mL 0.999840 0.999964 0.999972 0.999964 0.999699 0.999099 0.999012 0.998943 0.998774 0.996595 0.996404 0.998203
21.0 22.0 23.0 24.0 25.0 26.0 27.0 28.0 29.0 30.0 35.0 37.78
0.997991 0.997769 0.997537 0.997295 0.997043 0.996782 0.996511 0.996231 0.995943 0.995645 0.994029 0.993042
(5)
where: Tw = observed period of oscillation for cell containing water, T a = observed period of oscillation for cell containing air, dw = density of water at test temperature, and d,, = density of air at test temperature.
NOTE 5--In applying this weekly calibration procedure, it can be found that more than one value each for A and B, differing in the fourth decimal place, will yield the correct density reading for the density of air
0.0 3.0 4.0 5.0 10.0 15.0 15.56 16.0 17.0 18.0 19.0 20.0
(4)
40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 80.0 85.0 90.0 100
0.992212 0.990208 0.988030 0.985688 0.983191 0.980546 0.977759 0.974837 0.971785 0.968606 0.965305 0.958345
12. Calculation 12.1 Calculating D e n s i t y A n a l y z e r s - - T h e recorded value is the final result, expressed either as density in g/mL, kg/m 3 or as relative density. Note that kg/m 3 -- 1000 × g/mL.
A D(msities conforming to the InternationalTemperature Scale 1990 (ITS 90) were extracted from Appendix G, Standard Methods for Analysis of Petroleum and Related Products 1991, Institute of Petroleum, London.
623
~) D 4052 examination of intedaboratory test results at test temperatures of 15 and 20°C is as follows: 14.1.1 Repeatability--The difference between successive test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material, would in the long run, in the normal and correct operation of the test method, exceed the following value only in one case in twenty:
12.2 Noncalculating Density A n a l y z e r s - - U s i n g the observed T-value for the sample and the T-value for water and appropriate instrument constants determined in 10.4.3, calculate the density or relative density using Eqs 6 and 7. Carry out all calculations to six significant figures and round the final results to four. For density: density, g/rnL (kg/dm3) at t = dw + KI(Ts 2 - Tw2) (6) For relative density: relative density, t/t = 1 + K2(Ts2 - T2) (7) where: Tw = observed period of oscillation for cell containing water, Ts = observed period of oscillation for cell containing sample, dw = density of water at test temperature, K m = instrument constant for density, /(2 = instrument constant for relative density, and t = temperature of test, "C. 12.3 If it is necessary to convert a result obtained using the density meter to a density or relative density at another temperature, Guide D 1250 can be used only if the glass expansion factor has been excluded.
Range 0.68--0.97 g/mL
Repeatability 0.0001
14.1.2 Reproducibility--The difference between two single and independent results, obtained by different operators working in different laboratories on identical test material, would in the long run, in the normal and correct operation of the test method, exceed the following values only in one case in twenty: Range 0.68-0.97 g/mL
Reproducibility 0.0005
14.2 B i a s - - A f t e r suggestions of its existence from literature9, a study has been performed which has confirmed the presence of a bias between known density values for reference materials and from values determined according to this test method on the same reference materials. The matrix for this bias study comprised 15 participants, each analyzing four reference oils with certified density values, established by the Netherlands Meet Instituut (NMI), by pyknometry, covering densities in the range of 747 to 927 kg/m 3 at 20"C, with viscosities between 1 and 5 000 mPa.s (also at 20*C). This study is documented in ASTM Research Report RRD02-1387. Method users should, therefore, be aware that results obtained by this test method can be biased by as much as 0.6 kg/m 3 (0.0006 g/mL).
13. Report 13.1 In reporting density, give the test temperature and the units (for example: density at 200C = 0.8765 g/mL or 876.5 kg/m3). 13.2 In reporting relative density, give both the test temperature and the reference temperature, but no units (for example: relative density, 20/20°C = 0.xxxx). 13.3 Report the final result to the fourth decimal place.
15. Keywords 14. Precision and Biasa 14. l The precision ofthe method as obtained by statistical
15.1 density; digital density analyzer; petroleum distillates; petroleum products; relative density
s Statistical data b available as a research report from ASTM Headquarters. Request RR:D02-1387.
Petroleum Review, November 1992, pp. 544--549.
9 Fitzgerald, H. and D., "An Assessment of Laboratory Density Meters, ~
The American Society for Testing and Materials talcesno position respecting the validity of any patent rights asserted in connection with any item mentioned In this standard. Users Of this standard are expressly advised that determination Of the validity Of any such patent right& and the risk of Infringement of such rights, are entirely their own respon,slbllity. This atanbe~l is subject to revision at any time by the responsive technical committee and must be reviewed every five years and if not revised, enhar respproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at s meeting of the responsive technical committee, which you may attend. If you feel that your comments have not received • fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohocken, PA 19428.
624
Designation: D 4053 - 95
An Amencan National Standard
Standard Test Method for B e n z e n e in Motor and Aviation Gasoline by Infrared Spectroscopy 1 This standard is issued under the fixed designation D 4053; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
T = P/Po
1. Scope 1.1 This test method covers the determination of the percent benzene in full-range gasoline. It is applicable to concentrations from 0.1% to 5 volume %. 1.2 The values in SI units are regarded as the standard. 1.3 This test method has not been validated for gasolines containing oxygenates. 1.4 This standard does not purport to address all of the
where: P = the radiant power passing through the sample, and P,, = the radiant power incident upon the sample.
4. Summary of Test Method 4.1 A sample of gasoline is examined by infrared spectroscopy and, following a correction for interference, compared with calibration blends of known benzene concentration. From this comparison the amount of benzene in the gasoline is determined.
safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 8 and 9.1.
5. Significance and Use 5.1 Benzene is classed as a toxic material. A knowledge of the concentration of this compound may be an aid in evaluating the possible health hazard to persons handling and using the gasoline. This test method is not intended to evaluate such hazards.
2. Referenced Documents
2.1 ASTM Standards: D4057 Practice for Manual Sampling of Petroleum and Petroleum Products 2 E 131 Terminology Relating to Molecular Spectroscopy3 E 275 Practice for Describing and Measuring Performance of Ultraviolet, Visible, and Near Infrared Spectrophotometers 3
6. Interferences 6.1 Toluene and heavier aromatic compounds have some interference in this test method. In order to minimize the effect of such interference, this method includes a procedure that corrects for the error caused by the presence of toluene. Error due to other sources of interference may be partially compensated for by calibrating with gasoline stocks containing little or no benzene but which otherwise are similar in aromatic content to the samples to be analyzed.
3. Terminology
3.1 Definitions: 3.1.1 Definitions of terms and symbols relating to absorption spectroscopy in this test method shall conform to Terminology E 13 I. Terms of particular significance are the following: 3.1. I. l absorbance, A, n - - t h e molecular property of a substance that determines its ability to take up radiant power, expressed by: A = ioglo(l/T) = -log10 T
(2)
7. Apparatus 7.1 Absorption Cell, sealed. Windows of potassium bromide or other material having sufficient transmittance out to 440 cm -~ (22.73 Ixm), in a cell having TIE-fluorocarbon plugs and nominal path length of 0.025 mm known to three significant numbers. 7.2 Clear Reference Block--A block made from the same material as cell windows for use in the reference beam path of a double-beam spectrometer. 7.3 Infrared Spectrometer, double-beam or single-beam, suitable for recording accurate measurements between 690 cm -I (14.49 ~tm) and 440 cm -I (22.73 p.m). Refer to Practice E 275.
(l)
where T = the transmittance as defined in 3. I. 1.4. 3.1.1.2 radiant energy, n--energy transmitted as electromagnetic waves. 3. I. 1.3 radiant power, P, n - - t h e rate at which energy is transported in a beam of radiant energy. 3. I. 1.4 transmittance, T, n - - t h e molecular property of a substance that determines its transportability of radiant power, expressed by:
NOTE l - - A b s o r b a n c e s for the bands specified in this method are
This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee I)02.04 on Hydrocarbon Analysis. Current edition approved Sept. 10, 1995. Published November 1995. Originally published as D 4053 - 81. Last previous edition D 4053 - 91. 2 Annual Book of ASTM Standards, Vol 05.02. Annual Book of ASTM Standards, Vol 03.06.
expected to fall within the linear operating range of modern spectrometers for the concentration range as defined.
8. Reagents 8.1 Benzene, spectroscopic or research grade. (Warning-625
~
D 4053
Poison, carcinogen, harmful, or fatal if swallowed. Extremely flammable.) 8.2 Toluene, spectroscopic or research grade. (Warning-Flammable, harmful if inhaled.) 8.3 Isooctane (2,2,4-trimethylpentane) or n-Heptane, spectroscopic or research grade. (Warning--Isooctane and nHeptane are extremely flammable, harmful if inhaled.) 9. Sampling 9.1 Follow the procedures and precautions contained in Practice D 4057. (Warning~Gasolines are extremely flammable, harmful if inhaled.) 9.2 Cool the sample container and contents to 0 to 4"C before opening the container and transferring material to other containers. 10. Calibration and Standardization 10.1 Reference StandardsmPrepare standard blends of benzene using fresh, full-range gasoline of low benzene content (less than 1 volume percent) as the solvent. Measure and dilute all components at ambient temperature. Accurately pipet the required volume of benzene into 100-mL volumetric flasks partially filled with the gasoline. Dilute to volume with additional gasoline. Prepare the blends in I volume % increments. 10.2 Toluene StandardmPrepare a blend of toluene in either isooctane or n-heptane as the solvent. Measure and dilute all components at ambient temperature. Accurately pipet 2 mL of toluene into a 10-mL volumetric flask partially filled with either isooctane or n-heptane. Dilute to volume with the chosen solvent. 10.3 Calibration: 10.3.1 Following the steps of Section 11, Procedure, for each of the standard blends and the gasoline base stock, determine three absorbance values: (1) at the point of maximum absorbance near 673 cm-i (14.86 ~m), designated the benzene band; (2) at the point of maximum absorbance near 460 cm-t (21.74 ttm), designated the toluene band; and (3) at 500 cm -l (20.00 ~tm), designated the baseline position. 10.3.2 Following the steps of Section 11, Procedure, for the toluene standard, determine the absorbances at the locations described in 10.3.1 for the benzene band, the toluene band, and the baseline position. Subtract the baseline position value at about 500 cm -j from those found for benzene at about 673 cm -~ and toluene at about 460 cm -~ in order to obtain the net absorbance for each. Take the ratio of the benzene band net absorbance to the toluene band net absorbance to obtain the toluene correction factor. 10.3.3 For the gasoline base stock and each blend examined in 10.3. I, obtain the net absorbances at the benzene and the toluene bands by subtracting the baseline position value from the absorbances found for the band maxima. Continuing, for each liquid, multiply the toluene band net absorbance by the toluene correction factor found in 10.3.2 and subtract this value from the benzene band net absorbance in order to obtain the corrected net absorbance for the benzene band. 10.3.4 Construct a curve by plotting the benzene band corrected net absorbance for each calibration liquid, as found
626
in 10.3.3, divided by the cell path length in millimetres, versus the volume percent of added benzene for each. 10.3.5 Extrapolate the curve to zero absorbance. The absolute value of the intercept is the concentration of benzene in the gasoline used as the solvent. 10.3.6 Construct a standard reference curve by replotting the baseline absorbances per millimetre thickness, corrected in 10.3.5, against total concentration of benzene in percent by volume so that the curve passes through the origin. NOT~ 2--A linear equation can be used instead of the plot. 11. Procedure l I. 1 Clean the cell with isooctane or similar solvent and dry by means of a source of vacuum. 11.2 Fill the absorption cell with the gasoline to be tested. Both cell and sample should be at ambient temperature during this operation. If moisture condensation is a problem, blanket the cell with a dry, inert atmosphere. Use care to avoid formation of air pockets in the cell and scan immediately to prevent bubbles from forming. Observe the cell during the scan period to check for bubble formation. l l.3 Scan the infrared spectrum from 690 cm -I (14.99 lam) to 440 cm -I (22.73 lam) versus a clear reference block in the reference beam (for double-beam operation); follow the directions of the manufacturer for quantitative analysis. I 1.4 Determine the corrected net absorbance of the benzene band as described in 10.3.3. l l.5 Divide the benzene band corrected net absorbance, as found in I 1.4, by the cell path length in miilimetres. 12. Calculation 12.1 Calculate the benzene content of the gasoline in liquid volume percent by entering the calibration curve of 10.3.6 or the equation in Note 2 with the value of the benzene band found in 11.5. 12.2 If the results are desired on a weight basis, convert to mass percent, as follows: B = V x 0.8844/R (3) where: B = mass percent of benzene, V = volume percent of benzene, and R = relative density of sample, 15/15"C. 13. Report 13.1 Report numerical results to the nearest 0.1 volume %. 14. Precision and Bias 14.1 The precision of the method as obtained by statistical examination of interlaboratory results is as follows: 14.1.1 Repeatability--The difference between successive test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test materials, would in the long run, in normal and correct operation of the test method, exceed 0.08 volume % only in one case in twenty. 14.1.2 ReproducibilitymThe difference between two single and independent results, obtained by different operatots working in different laboratories on identical test material, would in the long run, in the normal and correct
(1~ D 4053 15. Keywords
operation of the test method exceed O. 18 volume % only in one case in twenty. 14.2 Bias--There are no interlaboratory test data to establish a statistical statement on bias.
15.1 aviation gasoline; benzene; infrared spectroscopy; motor gasoline
The American Society for Testing and Materials takes no position respecting the vah'dity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and ff not revised, either reepproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St,, Philadelphia, PA 19103.
627
Designation: D 4057 - 95 (1
IPW II. I , , I I H . I ~. I*It m . l U M
An American Naeonal Standard
Designation: MPMS (Chapter 8.1)
Standard Practice for Manual Sampling of Petroleum and Petroleum Products I This standard is issued under the fixed designation D 4057; the number immediately following the de~im~a~ionindicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (d indicates an editorial change since the last revision or reapproval. This test method has been approved by the sponsoring committees and accepted by the Cooperating Societies in accordance with established procedures. This method was issued as a joint A~FM-AP1 standard in 1981. et NOTEmEditorial correctious were made tu 8.3 in November 1997.
1. Scope
1.1 This practice covers procedures for manually obtaining representative samples of petroleum products of a liquid, semi-liquid, or solid state whose vapor pressure at ambient conditions is below 101 kPa (14.7 psia). If sampling is for the precise determination of volatility, use Practice D 5842 in conjunction with this practice. For sample mixing and handling of samples, refer to Practice D 5854. The practice does not cover sampling of electrical insulating oils and hydraulic fluids. A summary of the manual sampling procedures and their applications is presented in Table 1. NoT~ l--The procedures described in this method may also be applicable in sampl/ng most noncorrosiveliquid industrial chemicals, provided that all safety precautions specific to these chemicals are strictlyfollowed. NOtE 2--The procedure for sampling liquified petroleum gases is described in Practice D 1265; the procedure for sampling fluid power hydraulicfluidsis covered in ANSI B93.19 and B93.44; the procedure for samplinginsulatingotis is describedin Test Method D 923; and the procedure for samplingnatural gas is describedin Test Method D 1145. NOtE 3--The procedure for special fuel samples for trace metal analysisis describedin an appendixto SpecificationD 2880. 2. Referenced Documents 2.1 ASTM Standards: D 86 Test Method for Distillation of Petroleum Products2 D 217 Test Methods for Cone Penetration of Lubricating Grease 2 D 244 Test Methods for Emulsified Asphalts3 D 268 Guide for Sampling and Testing Volatile Solvents and Chemical Intermediates for Use in Paint and Related Coatings and Materials4 D323 Test Method for Vapor Pressure of Petroleum Products (Reid Method)2 1 This practice is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee 1302.02 on Static Petroleum Measurement (Joint ASTM-API). Current edition approved Nov. 10, 1995. Published January 1996. Originally published as D 4057 - 81. Last previous edition D 4057 - 88. 2 Annual Book of A S T M Standards, Vol 05.01. 3 Annual Book of A S T M Standards, Vol 04.03. 4 Annual Book of A S T M Standards, Vol 06.04.
D 346 Practice for Collection and Preparation of Coke Samples for Laboratory Analysiss D 525 Test Method for Oxidation Stability of Gasoline (Induction Period Method)2 D 873 Test Method for Oxidation Stability of Aviation Fuels (Potential Residue MethOd)2 D923 Test Method for Sampling Electrical Insulating Liquids6 D 977 Specification for Emulsified Asphalt3 D 1145 Test Method for Sampling Natural Cras5 D 1265 Practice for Sampling Liquefied Petroleum (LP) Gases--Manual MethOd2 D 1856 Test Method for Recovery of Asphalt from Solution by Abson Method 3 D 2172 Test Methods for Quantitative Extraction of Bitumen from Bituminous Paving Mixtures 3 D 2880 Specificationfor Gas Turbine Fuel Oils7 D 4177 Practicefor Automatic Sampling of Petroleum and Petroleum Products v D 4306 Practice for Aviation Fuel Sample Containers for Tests Affected by Trace Contamination 7 D5842 Practice for Mixing and Handling of Liquid Samples of Petroleum and Petroleum Products D 5854 Practice for Sampling and Handling of Fuels for VolatilityMeasurements 2.2 American National Standards: s B93.19 Standard Method for Extraction Fluid Samples from the Lines of an Operating Hydraulic Fluid Power System (for Particulate Contamination Analysis) B93.44 Method for Extracting Fluid Samples from the Reservoir of an Operating Hydraulic Fluid Power System 2.3 API Manual of Petroleum Measurement Standards: 9 Chapter 8.2 Automatic Sampling of Petroleum and Petroleum Products s Annual Book of A S T M Standards, Vo105.05. 6 Annual Book of A S T M Standards, Vol 10.03. 7 Annual Book of A S T M Standards, Vo105.02. s Available from American National Standards Institute, 11 W. 42rid St., 13th Floor, New York, NY 10036. 9 Available from American Petroleum Institute, 1220 L St., NW, Washington, DC 20O05.
628
~ TABLE 1
D 4057
Typical Sampling Procedures and Applicability
ApplicaUon
Type of Container
Liquids of more than (13.8 kPa) and not more than 101 kPa (14.7 psia) RVP
storage tanks, ship and barge tanks, tank cars, tank trucks
Liquids of 101 kPa (14.7 psia) RVP or less Bottom sampling of liquids of 13.8 kPa (2 psia) RVP or less Liquids of 101 kPa (14.7 psle) RVP or less Liquids of 13.8 kPe (2 psla) RVP or less Liquids of 13.8 kPe (2 psle) RVP or less Liquids of 13.8 kPa (2 psia) RVP or less Bottom or thief sampling of liquids of 13.8 kPa (2 psle) RVP or less Liquids and semMiquids of 13.8 kPe (2 psla) RVP or less
storage tanks with taps storage tanks with taps pipes or lines storage tanks, ships, barges free or open-dischergestreams drums, barrels, cans tank cars, storage tanks free or open-dischargestreams; open tanks or kettles with open heads; tank cars, tank trucks, drums storage tanks, ship and barge, tanks, tank cars, tank trucks,
Crude petroleum
p~p~ines
P~ure
~t~e sainting thief sampling tap ssmpllng samp,ng ~p~e ~ n g botUessrn~ng dipper sampling tube sampllng
san~g dipper sampling automaUc sarnpllng thief ssmpllng
Industrial aromatic hydrocarbons Waxes, solids b~m~ns, other soft solids Petroleum coke; lumpy solids Greases, soft waxes, asphalts Asphaltic materials Emulsified asphalts
storage tanks, ship and barge tanks barrels, cases, bags, cakes freight cars, conveyors, bags, barrels, boxes kettles, drums, cans, tubes storage tanks, tank cars, lines, packages storage tanks, tank cars, lines, packages
Chapter 8.3 Standard Practice for Mixing and Handling of Liquid Samples of Petroleum and Petroleum Products Chapter 8.4 Standard Practice for the Sampling and Handling of Fuels for Volatility Measurements Chapter 9.3 Thermohydrometer Test Method for Density and API Gravity of Crude Petroleum and Liquid Petroleum Products Chapter 17.1 Guidelines for Marine Cargo Inspection Chapter 17.2 Measurement of Cargoes Aboard Marine Tank Vessels Chapter 18.1 Measurement Procedures for Crude Oil Gathered from Small Tanks By Truck Chapter 10, various sections, Sediment and Water Determination
borne ssmpl~g tap s~npling bottle sampling boring sampling grab sampling greasesampling
regulatory agencies require 15 cm (6 in.)) below the bottom of the tank outlet. (a) Discussion--This term is normally associated with small (159 m a or 1000 Bbls or less) tanks, commonly referred to as lease tanks. 3.1.1.6 composite sample--a blend of spot samples mixed in proportion to the volumes of material from which the spot samples were obtained. 3.1.1.7 core sample--a sample of uniform cross sectional area taken at a given height in a tank. 3.1.1.8 dipper sample--a sample obtained by placing a dipper or other collecting vessel in the path of a free-flowing stream to collect a definite volume from the full cross section of the stream at regular time intervals for a constant time rate of flow or at time intervals varied in proportion to the flow rate. 3.1.1.9 drain sample--a sample obtained from the water draw-off valve on a storage tank. (a) Discussion--Occasionally, a drain sample may be the same as a bottom sample (for example, in the case of a tank car). 3.1.1.10 floating roof samplema spot sample taken just below the surface to determine the density of the liquid on which the roof is floating. 3.1.1.11 flow proportional sample--a sample taken from a pipe such that the rate of sampling is proportional throughout the sampling period to the flow rate of the fluid in the pipe. 3.1.1.12 grab sample--a sample obtained by collecting equal quantities from parts or packages of a shipment of loose solids such that the sample is representative of the entire shipment. 3.1.1.13 grease samplema sample obtained by scooping or dipping a quantity of soft or semi-liquid material conrained from a package in a representative manner. 3.1.1.14 lower sample~a spot sample of liquid from the middle of the lower one-third of the tank's content (a distance of five-sixths of the depth liquid below the liquid's surface). See Fig. 1.
3. Terminology 3.1 Description of Terms Specific to This Standard: 3.1.1 Samples: 3.1.1.1 all-levels sample--a sample obtained by submerging a stoppered beaker or bottle to a point as near as possible to the draw-off level, then opening the sampler and raising it at a rate such that it is approximately three-fourths full as it emerges from the liquid. 3.1.1.2 boring sample--a sample of the material conrained in a barrel, case, bag, or cake that is obtained from the chips created by boring holes into the material with a ship auger. 3.1.1.3 bottom sample--a spot sample collected from the material at the bottom of the tank, container, or line at its lowest point. (a) Discussion--In practice, the term bottom sample has a variety of meanings. As a result, it is recommended that the exact sampling location (for example, 15 cm from the bottom) should be specified when using this term. 3.1.1.4 bottom water sample--a spot sample of free water taken from beneath the petroleum contained in a ship or barge compartment or a storage tank. 3.1.1.5 clearance samplema spot sample taken with the inlet opening of the sampling apparatus 10 cm (4 in.) (some 629
~
D 4057
Hatch
,[--15 cm (6") I
~ Tank contents
Outlet
Top sample Upper sample
Upper third
X
Middle sample
Middle third
×
Lower sample /~-- Outlet sample
Lower third
Bottom sample
NOTE 1--The location shown for the outlet sample applies only to tanks with side outleta, it doas not apply when the outlet comes from the floor of the tank or turns down into a sump. Bottom sample location must be specified. NOTE 2 ~ should be obtained from within solid stand pipes as the materials normally not representative of the material in the tank at that point. FIG. 1 Spot Sampling Locations
3.1.1.15 middle sample--a spot sample taken from the middle tank's contents (a distance of one-half of the depth of liquid below the liquid's surface). See Fig. 1. 3.1.1.16 multiple tank composite sample--a mixture of individual samples or composites of samples that have been obtained from several tanks or ship/barge compartments containing the same grade of material. (a) Discussion--The mixture is blended in proportion to the volume of material contained in the respective tanks or compartments. 3.1.1.17 outlet sample--a spot sample taken with the inlet opening of the sampling apparatus at the level of the bottom of the tank outlet (fixed or floating). See Fig. 1. 3.1.1.18 representative sample--a portion extracted from the total volume that contains the constituents in the same proportions that are present in that total volume. 3. I. 1.19 running sample--a sample obtained by lowering a breaker or bottle to the level of the bottom of the outer connection or swing line and returning it to the top of the oil at a uniform rate such that the beaker or bottle is about three-fourths full when withdrawn from the oil. 3. I. 1.20 sample--a portion extracted from a total volume that may or may not contain the constituents in the same proportions that are present in that total volume. 3.1.1.21 sampling--all the steps required to obtain a sample that is representative of the contents of any pipe, tank, or other vessel and to place that sample in a container from which a representative test specimen can be taken for analysis. 3.1.1.22 spot sample--a sample taken at a specific location in a tank or from a flowing stream in a pipe at a specific time. 3.1.1.23 su(face sample--a spot sample skimmed from the surface of a liquid in a tank. 3.1.1,24 tank composite sample--a blend created from the upper, middle, and lower samples from a single tank. (a) Discussion--For a tank of uniform cross section, such as an upright cylindrical tank, the blend consists of equal parts of the three samples. For a horizontal cylindrical tank, 630
the blend consists of three samples in the proportions shown in Table 2. 3.1.1.25 tap sample--a spot sample taken from a sample tap on the side of a tank. It may also be referred to as a tank-side sample. 3.1.1.26 top sample--a spot sample obtained 15 cm (6 in.) below the top surface of the liquid. See Fig. I. 3.1.1.27 tube or thief sample--a sample obtained with a sampling tube or special thief, either as a core sample or spot sample from a specific point in the tank or container. 3.1.1.28 upper sample--a spot sample taken from the middle of the upper one-third of the tank's contents (a distance of one-sixth of the liquid depth below the liquid's surface). See Fig. 1. 3.1.2 Other Terms: 3.1.2.1 automatic sampler--a device used to extract a representative sample from the liquid flowing in a pipe. (a) Discussion--The automatic sampler generally consists of a probe, a sample extractor, an associated controller, a flow measuring device, and a sample receiver. For additional information on an automatic sampler, see Practice D 4177. 3.1.2.2 dissolved water--water in solution in an oil. 3.1.2.3 emulsion--an oil/water mixture that does not readily separate. 3.1.2.4 entrained water--water suspended in the oil. (a) Discussion--Entrained water includes emulsions but does not include dissolved water. 3.1.2.5 free water--the water that exists as a separate phase. 3.1.2.6 intermediate container--the vessel into which all or part of the sample from a primary container/receiver is transferred for transport, storage, or ease of handling. 3.1.2.7 primary sample receiver/receptacle--a container in which a sample is initially collected. (a) Discussion--Examples of primary sampler containers include glass and plastic bottles, cans, core-type thief, and fixed and portable sample receivers. 3.1.2.8 stand pipes--verdcal sections of pipe or tubing extending from the gaging platform to near the bottom of tanks that are equipped with external or internal floating roofs. (a) Discussion--Stand pipes may also be found on ships and barges. 3.1.2.9 test specimen--the representative sample taken from the primary or intermediate sample container for analysis. TABLE 2
Uqu~ Depth (S of
Sampling Instructions for Horizontal Cylindrical Tanks
Samp~g L e ~ (% of DiameterAbove Bottom)
Compos~ Ssm~e (Proportionate Parts Of)
Diameter)
Upper
Middle
Lower
Upper
Middle
Lower
100 90 80 70 6O 50 40 30 20 10
80 75 70
50 50 50 50 5O 40
20 20 20 20 20 20 20 15 10 5
3 3 2
4 4 5
3 3 3
6
4
5 4
5 6 10 10 10 10
(~) D 4057 of the sample(s). Therefore, the sampling operation should be conducted before innage gaging, the associated temperature determination, and any other similar activity that could disturb the tank contents. 6.1.2.2 To avoid contamination of the oil column during the sampling operation, the order of precedence for sampling should start from the top and work downward, according to the following sampling sequence: surface, top, upper, middle, lower, outlet, clearance, all-levels, bottom, and running sample. 6.1.3 Equipment Cleanliness--The sampling equipment should be clean prior to commencing the sampling operation. Any residual material left in a sampling device or sample container from a previous sample or cleaning operation may destroy the representative character of the sample. It is good practice with light petroleum products to rinse the container with the product to be sampled prior to drawing samples.
4. Summary of Practice 4.1 This practice provides procedures for manually obtaining samples of petroleum and petroleum products of a liquid, semi-liquid or solid state from tanks, pipelines, drums, barrels, cans, tubes, bags, kettles and open-discharge streams. It addresses, in detail, the various factors which need to be considered in obtaining a representative sample. These considerations include the analytical tests to be conducted on the sample, the types of sample containers to be used and any special instructions required for special materials to be sampled. Test Method D 5854 can provide additional guidance. 5. Significance and Use 5.1 Representative samples of petroleum and petroleum products are required for the determination of chemical and physical properties, which are used to establish standard volumes, prices, and compliance with commercial and regulatory specifications. 5.2 The following concepts must be considered when selecting a specific sampling procedure.
6.1.4 Compositing of Individual Samples." 6.1.4.1 If the sampling procedure requires that several different samples be obtained, physical property tests may be performed on each sample or on a composite of the various samples. When the respective tests are performed on individual samples, which is the recommended procedure, the test results are averaged generally. 6.1.4.2 When a multiple tank composite sample is required, such as on board ships and barges, a composite tank sample may be prepared from the samples from different tanks when they contain the same material. In order for such a composite tank sample to be representative of the material contained in the various tanks, the quantity from the individual samples used to prepare the composite tank sample must be proportional to the volumes in the corresponding tanks. In most other compositing situations, equal volumes from the individual samples must be used. The method of compositing should be documented and care taken to preserve the integrity of the samples. It is recommended that a portion of each tank sample be retained separately (not composited) for retesting if necessary. 6.1.4.3 When compositing samples, exercise care to ensure sample integrity. Refer to Practice D 5854 for guidance on mixing and handling of samples. 6.1.4.4 Samples taken at specific levels, for example, upper-middle-lower capping will require a small portion of the sample to be poured out to create an ullage in the container before capping. All other samples shall be capped immediately and taken to the laboratory. 6.1.5 Sample TransfersmThe number of intermediate transfers from one container to another between the actual sampling operation and testing should be minimized. The loss of light hydrocarbons as the result of splashing, loss of water due to clingage, or contamination from external sources, or both, may distort test results, for example, density, sediment and water, product clarity. The more transfers between containers, the greater the likelihood one or both of these problems may occur. See Practice D 5854 for additional information concerning the handling and mixing of samples. 6.1.6 Sample StoragemExcept when being transferred, samples should be maintained in a closed container in order to prevent loss of light components. Samples should be
5.2.1 Objectiveof Manual Sampling: 5.2.1.1 The objective of manual sampling is to obtain a small portion (spot sample) of material from a selected area within a container that is representative of the material in the area or, in the case of running or all-level samples, a sample whose composition is representative of the total material in the container. A series of spot samples may be combined to create a representative sample.
5.2.2 Required Conditions for the Application of Manual Sampling: 5.2.2.1 Manual sampling may be applied under all conditions within the scope of this practice, provided that the proper sampling procedures are followed. 5.2.2.2 In many liquid manual sampling applications, the material to be sampled contains a heavy component (such as free water) which tends to separate from the main component. In these cases, manual sampling is appropriate under the following conditions. (a) Sufficient time must have elapsed for the heavy component to adequately separate and settle. (b) It must be possible to measure the level of the settled component in order to stay well above that level when drawing representative samples, unless all or part of the heavy component will be included in the portion of the tank contents to be identified. (c) When one or more of these conditions cannot be met, sampling is recommended and is accomplished by means of an automatic sampling system (see Practice D 4177). 6. Manual Sampling Considerations 6.1 The following factors must be considered in the development and application of manual sampling procedures: 6.1.1 Physical and Chemical Property Tests~The physical and chemical property tests to be performed on a sample will dictate the sampling procedures, the sample quantity required, and many of the sample handling requirements.
6.1.2 Sampling Sequence: 6.1.2.1 Any disturbance of the material in a tank that is to be sampled may adversely affect the representative character 631
~
D 4057 problem with solubility, contamination, or loss of light components. 7.4.1 In no circumstances shall nonlinear (conventional) polyethylene containers be used to store samples of liquid hydrocarbons. This is to avoid sample contamination or sample bottle failure. Used engine oil samples that may have been subjected to fuel dilution should not be stored in plastic containers. 7.4.2 Plastic bottles have an advantage in that they will not shatter like glass or corrode like metal containers. 7.5 Cans--When cans are to be used, they must have seams that have been soldered on the exterior surfaces with a flux of rosin in a suitable solvent. Such a flux is easily removed with gasoline, whereas many others are very difficult to remove. Minute traces of flux may contaminate the sample so that results obtained on tests such as dielectric strength, oxidation resistance, and sludge formation may be erroneous. Internal epoxy lined cans may have residual contamination and precautions should be taken to ensure its removal. Practice D 4306 should be used when taking samples for aviation fuels. 7.6 Container Closures--Cork stoppers, or screw caps of plastic or metal may be used for glass bottles. Corks must be of good quality, clean, and free from holes and loose bits of cork. Never use rubber stoppers. Prevent the sample from contacting the cork by wrapping fin or aluminum foil around the cork before forcing it into the bottle. Screw caps providing a vapor tight closure seal shall be used for cans. Screw caps must be protected by a disk faced with material that will not deteriorate and contaminate the sample. Containers used to take samples that will be tested for density or gravity shall have screw caps. 7.7 Cleaning Procedure--Sample containers must be clean and free from all substances which might contaminate the material being sampled (such as water, dirt, lint, washing compounds, naphtha and other solvents, soldering fluxes, acids, rust, and oil). Prior to further use, reusable containers such as cans and bottles should be rinsed with a suitable solvent. Use of sludge solvents to remove all traces of sediments and sludge may be necessary. Following the solvent wash, the container should be washed with a strong soap solution, rinsed thoroughly with tap water, and given a final rinse using distilled water. Dry the container either by passing a current of clean warm air through the container or by placing it in a hot dust-free cabinet at 40°C (104*F) or higher. When dry, stopper or cap the container immediately. Normally, it is not necessary to wash new containers. 7.7.1 Depending on service, receivers used in conjunction with automatic samplers may need to be washed with solvent between uses. In most applications, it is not desirable or practical to wash these receivers using soap and water as outlined above for cans and bottles. The cleanliness and integrity of all sample containers/receivers must be verified prior to use. 7.7.2 When sampling aviation fuel, Practice D4306 should be consulted for recommended cleaning procedures for containers that are to be used in tests for the determination of water separation, copper corrosion, electrical conductivity, thermal stability, lubricity, and trace metal content. 7.8 Sample Mixing Systems--The sample container should be compatible with the mixing system for remixing
protected during storage to prevent weathering or degradation from light, heat, or other potential detrimental conditions. 6.1.7 Sample Handling--If a sample is not uniform (homogeneous) and a portion of the sample must be transferred to another container or test vessel, the sample must be thoroughly mixed in accordance with the type of material and appropriate test method, in order to ensure the portion transferred is representative. Exercise care to ensure mixing does not alter the components within the sample, for example, loss of light ends. See Practice D 5854 for more detailed instructions.
7. Apparatus 7.1 Sample containers come in a variety of shapes, sizes, and materials. To be able to select the right container for a given application one must have knowledge of the material to be sampled to ensure that there will be no interaction between the sampled material and the container which would affect the integrity of the other. Additional considerations in the selection of sample containers is the type of mixing required to remix the contents before transferring the sample from the container and the type of laboratory analyses that are to be conducted on the sample. To facilitate the discussion on proper handling and mixing of samples, sample containers are referred to as either primary or intermediate containers. Regardless of the type of sample container used, the sample container should be large enough to contain the required sample volume without exceeding 80 % of the container capacity. The additional capacity is required for thermal expansion of the sample and enhances sample mixing. 7.2 GeneralContainer Design Considerations--Following are general design considerations for sample containers: 7.2.1 The bottom of the container should be sloped continuously downward to the outlet to ensure complete liquid withdrawal. 7.2.2 There should be no internal pockets or dead spots. 7.2.3 Internal surfaces should be designed to minimize corrosion, encrustation, and water/sediment clingage. 7.2.4 There should be an inspection cover/closure of sufficient size to facilitate filling, inspection, and cleaning. 7.2.5 The container should be designed to allow the preparation of a homogeneous mixture of the sample while preventing the loss of any constituents which affect the representativeness of the sample and the accuracy of the analytical tests. 7.2.6 The container should be designed to allow the transfer of samples from the container to the analytical apparatus while maintaining their representative nature. 7.3 Bottles (Glass)--Clear glass bottles may be examined visually for cleanliness and allows visual inspection of the sample for free water cloudiness, and solid impurities. Brown glass bottles afford some protection to the samples when light may affect the test results. 7.4 Bottles (Plastic)--Plastic bottles made of suitable material may be used for the handling and storage of gas oil, diesel oil, fuel oil, and lubricating oil. Bottles of this type should not be used for gasoline, aviation jet fuel, kerosine, crude oil, white spirit, medicinal white oil, and special boiling point products unless testing indicates there is no 632
~
D 4057 near the bottom. The running sample or the composite of the upper, middle, and lower sample may not represent the concentration of entrained water. 9.1.1.2 The interface between oil and free water is difficult to measure, especially in the presence of emulsion layers, or sludge. 9.1.1.3 The determination of the volume of free water is difficult because the free water level may vary across the tank bottom surface. The bottom is often covered by pools of free water or water emulsion impounded by layers of sludge or wax. 9.1.2 Automatic sampling in accordance with Practice D 4177 is recommended whenever samples of these materials are required for custody transfer measurements. However, tank samples may be used when agreed to by all parties to the transaction. 9.2 Gasoline and Distillate Products--Gasoline and distillate products are usually homogeneous, but they are ot~en shipped from tanks that have clearly separated water on the bottom. Tank sampling, in accordance with the procedures outlined in Section 13, is acceptable under the conditions covered in 5.2.2. 9.3 Industrial Aromatic Hydrocarbons--For samples of industrial aromatic hydrocarbons (benzene, toluene, xylene, and solvent naphthas), proceed in accordance with Sections 5.2.1, 7, and 10, and Sections 12.2 through 13, with particular emphasis on the procedures pertaining to the precautions for care and cleanliness. See Annex A1 for details. 9.4 Lacquer Solvents and Diluents: 9.4.1 When sampling bulk shipments of lacquer solvents and diluents which are to be tested using Test D 268, observe the precautions and instructions described in 9.4.2 and 9.4.3. 9.4.2 Tanks and Tank Cars--Obtain upper and lower samples (see Fig. 1) of not more than 1 L (qt) each by the thief or bottle spot sampling procedures outlined in 13.4. In the laboratory, prepare a composite sample of not less than 2 L/2 qts by mixing equal parts of the upper and lower samples. 9.4.3 Barrels, Drums, and Cans--Obtain samples from the number of containers per shipment as mutually agreed. In the case of expensive solvents, which are purchased in small quantities, it is recommended that each container be sampled. Withdraw a portion from the center of each container to be sampled using the tube sampling procedure (see 9.4.3) or bottle sampling procedure (see 13.4.2, although a smaller bottle may be used). Prepare a composite sample of at least 1 L (1 qt) by mixing equal portions of not less than 500 mL (1 pt) from each container sampled. 9.5 Asphaltic Materials--When sampling asphaltic materials that are to be tested using Test Method D 1856 or Test Method D 2172, obtain samples by the boring procedure in Section 17 or the grab procedure in Section 18. A sample of sufficient size to yield at least 100 g (I/4 lb) of recovered bitumen is required. About 1000 g (2 lb) of sheet asphalt mixtures usually will be sufficient. If the largest lumps in the sample are 2.5 cm (1 in.), 2000 g (4 lb) will usually be required, and still larger samples if the mixture contains larger aggregates. 9.6 Emulsified Asphalts--It is frequently necessary to test samples in accordance with the requirements of Specification
samples that have stratified to ensure that a representative sample is available for transfer to an intermediate container or the analytical apparatus. This is especially critical when remixing crude, some black products, and condensates for sediment and water analysis to ensure a representative sample. The requirements governing the amount of mixing and type of mixing apparatus differ depending upon the petroleum or petroleum product and the analytical test to be performed. Refer to Practice D 5854 for more detailed information. 7.8.1 When stratification is not a major concern, adequate mixing may be obtained by such methods as shaking (manual or mechanical), or use of a shear mixer. 7.8.2 Manual and mechanical shaking of the sample container are not recommended methods for mixing a sample for sediment and water (S&W) analysis. Tests have shown it is difficult to impart sufficient mixing energy to mix and maintain a homogeneous representative sample. Practice D 5854 contains more detailed information. 7.9 Other EquipmentmA graduated cylinder or other measuring device of suitable capacity is often required for determining sample quantity in many of the sampling procedures and for compositing samples. 7.10 Sampling DevicesmSampling devices are described in detail under each of the specific sampling procedures. Sampling devices shall be clean, dry, and free of all substances that might contaminate the material being sampled.
8. Special Precautions 8.1 This practice does not purport to cover all safety aspects associated with sampling. However, it is presumed that the personnel performing sampling operations are adequately trained with regard to the safe application of the procedures contained herein for the specific sampling situation. 8.2 A degree of caution is required during all sampling operations, but in particular when sampling certain products. Crude oil may contain varying amounts of hydrogen sulfide (sour crude), an extremely toxic gas. Annex A I provides precautionary statements that are applicable to the sampling and handling of many of these materials. 8.3 When taking samples from tanks suspected of containing flammable atmospheres, precautions should be taken to guard against ignitions from static electricity. Conductive objects, such as gage tapes, sample containers, and thermometers, should not be lowered into or suspended in a compartment or tank that is being filled, or immediately after cessation of pumping. Conductive material such as gage tape should always be in contact with gage tube until immersed in the fluid. A waiting period (normally 30 rain or more after filling cessation) will generally be required to permit dissipation of the electrostatic charge. In order to reduce the potential for static charge, nylon or polyester rope, cords, or clothing should not be used. 9. Special Instructions for Specific Materials 9.1 Crude Petroleum and Residual Fuel Oils: 9. I. 1 Crude petroleum and residual fuel oils usually are nonhomogeneous. Tank samples of crude oil and residual oils may not be representative for the following reasons: 9.1.1.1 The concentration of entrained water is higher 633
lib O 4057 them to temperatures above those necessitated by atmospheric conditions. 10.4.3 Sample ContainersmUse only brown glass or wrapped clear glass bottles as containers, since it is difficult to make certain that cans are free of contaminants, such as rust and soldering flux. Clean the bottles by the procedure described in 7.7. Rinse thoroughly with distilled water, dry, and protect the bottles from dust and dirt. 10.4.4 SamplingmA running sample obtained by the procedure in 13.5 is recommended because the sample is taken directly in the bottle. This reduces the possibility of air absorption, loss of vapors, and contamination. Just before sampling, rinse the bottle with the product to be sampled.
D977, and Test Methods D 244. Obtain samples from tanks, tank cars, and tank trucks by the bottle sampling procedure outlined in 13.4.2 using a bottle that has a 4-cm (1 l/2-in.) diameter or larger mouth. Refer to Fig. 1 and Table 2 for sampling locations. Use the dipper procedure in Section 15 to obtain samples for fill or discharge lines. Sample packages in accordance with Table 3. If the material is solid or semisolid, use the boring sampling procedure described in Section 17. Obtain at least 4 L (1 gal) or 4.5 Kg (10 lbs) from each lot or shipment. Store the samples in clean, airtight containers at a temperature of not less than 4"C (40*F) until the test. Use a glass or black iron container for emulsified asphalts of the RS- 1 type.
11. Special Instructions for Specific Applications 11.1 Marine Cargoes of Crude Oils: 11.1.1 Samples of ship or barge cargoes of crude petroleum may be taken by mutual agreement by the following methods: 11.1.1.1 From the shore tanks before loading and both before and after discharging as in Section 13. 11.1.1.2 From the pipeline during discharging or loading. Pipeline samples may be taken either manually or with an automatic sampler. If the pipeline requires displacement or flushing, exercisecare that the pipeline sample includes the entirecargo and none of the displacement. Separate samples may be required to cover the effectof the line displacement on the prior or following transfer. I I.I.1.3 From the ship'sor barge's tanks afterloading or before discharging. An all-levelssample, running sample, upper-middle-lower sample, or spot samples at agreed levels may be used for sampling each cargo compartment of a ship or barge. 11.1.2 Ship and barge samples may be taken either through open hatches or by use of equipment designed for closed systems. I I.I.3 Normally, when loading a marine vessel,the shore tank sample or the pipeline sample taken from the loading line is the custody transfer sample. However, ship's/barge's tank samples may also be tested for sediment and water (S&W) and for other quality aspects, when required. The resultsof these ship's/barge'stank sample tests,togetherwith the shore tank sample tests,may be shown on the cargo certificate. 11.1.4 When discharging a ship/barge, the pipeline sample taken from a properly designed and operated automatic line sampler, in the discharge line, should be the custody transfer sample. Where no proper line sample is available, the ship's/barge's tank sample can be the custody transfer sample except where specifically exempted. 11.1.5 Samples of ship/barge cargoes of finished products are taken from both shipping and receiving tanks and from the pipeline, if required. In addition, the product in each of the ship/barge tanks should be sampled after the vessel is loaded or just before unloading.
10. Special Instructions for Specific Tests 10.1 General--Special sampling precautions and instructions are required for some ASTM test methods and specifications. Such instructions supplement the general procedures of this practice and supersede them if there is a conflict. 10.2 Distillation of Petroleum Products~When obtaining samples of natural gasoline that are to be tested using Test Method D 86, the bottle sampling procedure described in 13.4.2 is the preferred technique, with the exception that pre-cooled bottles and laboratory compositing is required. Before obtaining the sample, pre-cool the bottle by immersing it in the product, allowing it to fill, and discard the first filling. If the bottle procedure cannot be used, obtain the sample by the tap procedure and with the use of the cooling bath, as described in 13.6. Do not agitate the bottle while drawing the sample. After obtaining the sample, close the bottle immediately with a tight-fitting stopper, and store it in an ice bath or refrigerator at a temperature of 0 to 4.5"C (32 to 400F). 10.3 Vapor Pressure~When sampling petroleum and petroleum products that are to be tested for vapor pressure, refer to Practice D 5842. 10.4 Oxidation Stability: 10.4.1 When sampling products that are to be tested for oxidation stability in accordance with Test Method D 525, Test Method D 873, or equivalent methods, observe the precautions and instructions that follow. 10.4.2 PrecautionsmVery small amounts (as low as 0.001%) of some materials, such as inhibitors, have a considerable effect upon oxidation stability tests. Avoid contamination and exposure to light while taking and handling samples. To prevent undue agitation with air, which promotes oxidation, do not pour, shake, or stir samples to any greater extent than necessary. Never expose TABLE 3
Minimum Number of Packages to b e Selected for Sampling
Packages in Lot
Packages to be Sampled
1 to 3 4 to 64 65 to 125 126 to 216 217 to 343 344 to 512 513 to 729 730 to 1000 1001 to 1331
all 4 5 6 7 8 9 10 11
Packages in Lot 1332 to 1728 1729 to 2197 2198 to 2744 2745 to 3375 3376 to 4096 4097 to 4913 4914 to 5832 5833 to 6859 6850 and greater
Packages to be Sampled 12 13 14 15 16 17 18 19 20
NOTE 4--Refer to M P M S Chapter 17 for additional requirements associated with sampfing materials in marine vessels.
11.2 Crude Oil Gathered By Truck--Refer to MPMS Chapter 18.1 for additional sampling requirements when gathering crude oil by tank truck. l l.3 Tank Cars--Sample the material after the car has 634
(~ D 4057 been loaded or just before unloading. 11.4 Package Lots (Cans, Drums, Barrels, or Boxes)-Take samples from a sufficient number of the individual packages to prepare a composite sample that will be representative of the entire lot or shipment. Select at random the individual packages to be sampled. The number of random packages will depend on several practical considerations, such as (1) the tightness of the product specifications; (2) the sources and type of the material and whether or not more than one production batch may be represented in the load and (3) previous experience with similar shipments, particularly with respect to the uniformity of quality from package to package. In most cases, the number specified in Table 4 will be satisfactory.
be sampled and drained before it is filled with the actual sample. 12.2.5 The transfer of crude oil samples from the sample apparatus/receiver to the laboratory glassware in which they will be analyzed requires special care to maintain their representative nature. The number of transfers should be minimized. Mechanical means of mixing and transferring the samples in the sample receiver are recommended. 12.3 Sample Handling: 12.3.1 Volatile SamplesmAll volatile samples of petroleum and petroleum products shall be protected from evaporation. Transfer the product from the sampling apparatus to the sample container immediately. Keep the container closed except when the material is being transferred. After delivery to the laboratory, volatile samples should be cooled before the containers are opened. 12.3.2 Light Sensitive SamplesmIt is important that samples sensitive to light, such as gasoline, be kept in the dark, if the testing is to include the determination of such properties as color, octane, tetraethyl lead and inhibitor contents, sludge forming characteristics, stability tests, or neutralization value. Brown glass bottles may be used. Wrap or cover clear glass bottles immediately. 12.3.3 Refined Materials~Protect highly refined products from moisture and dust by placing paper, plastic, or metal foil over the stopper and the top of the container. 12.3.4 Container Outage~Never fill a sample container completely. Allow adequate room for expansion, taking into consideration the temperature of the liquid at the time of filling, and the probable maximum temperature to which the filled container may be subjected. Adequate sample mixing is difficult if the container is more than 80 % full. 12.4 Sample Labeling--Label the container immediately after a sample is obtained. Use waterproof and oil proof ink or a pencil hard enough to dent the tag. Soft pencil and ordinary ink markers are subject to obliteration from moisture, oil smearing, and handling. Include the following information on the label: 12.4.1 Date and time (the period elapsed during continuous sampling and the hour and minute of collection for dipper samples), 12.4.2 Name of the sampler, 12.4.3 Name and number and owner of the vessel, car, or container, 12.4.4 Grade of material, and 12.4.5 Reference symbol or identification number. 12.5 Sample Shipment--To prevent loss of liquid and vapors during shipment and to protect against moisture and dust, cover the stoppers of glass bottles with plastic caps that have been swelled in water, wiped dry, placed over the tops of the stoppered bottles, and allowed to shrink tightly in place. Before filling metal containers, inspect the lips and caps for dents, out-of-roundness, or other imperfections. Correct or discard the cap or container, or both. After filling, screw the cap tightly and check for leaks. Appropriate governmental and carder regulations applying to the shipment of flammable liquids must be observed.
12. Sampling Procedures (General) 12.1 The standard sample procedures described in this practice are summarized in Table 1. Alternative sampling procedures may be used if a mutually satisfactory agreement has been reached by the parties involved. It is recommended that such agreements be put in writing and signed by authorized officials. 12.2 Precautions: 12.2.1 Extreme care and good judgment are necessary to ensure that samples are obtained that represent the general characteristics and average condition of the material. Clean hands are important. 12.2.2 Since many petroleum vapors are toxic and flammable, avoid breathing them, igniting them from an open flame, burning embers, or a spark produced by static electricity. All safety precautions specific to the material being sampled should be followed. 12.2.3 When sampling relatively volatile products more than 13.8 kPa (2 psia) RVP, the sampling apparatus shall be fiUed and allowed to drain before drawing the sample. If the sample is to be transferred to another container, this container shall also be rinsed with some of the volatile product and then drained. When the actual sample is emptied into this container, the sampling apparatus should be upended into the opening of the sample container and should remain in this position until the contents have been transferred so that no unsaturated air will be entrained in the transfer of the sample. 12.2.4 When sampling nonvolatile liquid products, 13.8 kPa (2 psia) RVP or less, sampling apparatus shall be filled and allowed to drain before drawing the actual sample. If the actual sample is to be transferred to another container, the sample container shall be rinsed with some of the product to TABLE 4
Spot Sampling Requirement~
NoTE--When samples are I'equlred at more thai3orte location in the tank, the samples shall be obtained beginning with the upper sample first and progressing sequentially to the lower sample. Tank Capacity/Liquid Level Tank capacity less than or equal to 159 ma (1 000 bbls) Tank capacity greater than 159 ma (1 000 bbls) Level < 3 m (10 ft) 3 m (10 ft) < Level s 4.5 m (15 ft) Level > 4.5 m (15 ft)
Required Samples Upper
Middle
Lower
X X
X
X
13. Tank Sampling 13.1 Samples should not be obtained from within solid stand pipes as the material is normally not representative of
X X X
X
X X
635
~
D 4057
the material in the tank at that point. Stand pipe samples should only be taken from pipes with at least two rows of overlapping slots.See Fig. 2. 13.2 When sampling crude oil tanks with diameters in excess of 45 m 050 it),additional samples should be taken from any other availablegaging hatches located around the perimeter of the tank roof, safety requirements permitting. All the samples should be individually analyzed using the same test method and the results should then be averaged arithmetically. 13.3 Composite Sample Preparation--A composite spot sample is a blend of spot samples mixed volumetrically proportional for testing. Some tests may also be made on the spot samples before blending and the results averaged. Spot samples from crude oil tanks are collected in the following ways: 13.3.1 Three-way--On tanks larger than 159 m 3 (1000 bbls) capacity, which contain in excess of 4.5 m (15 it) ofoil, equal volume samples should be taken at the upper, middle, and lower or outlet connection of the merchantable oil, in the order named. This method may also be used on tanks up to and including a capacity of 159 m 3 (1000 bbls). 13.3.2 Two-way---On tanks smaller than 159 m 3 (1000 bbls) capacity, which contain in excess of 3 m (10 it) and up to 4.5 m (15 it) of oil, equal volume samples should be taken at the upper and lower, or outlet connection of the merchantable oil, in the order named. This method may also be used on tanks up to and including a capacity of 159 m 3 (1000 bbls). 13.4 Spot Sampling Methods--The requirements for spot sampling are shown in Table 4. For sampling locations, see Fig. 1. 13.4.1 Core Thief Spot SamplingProcedure." 13.4.1.1 Application--Thecore thief spot sampling procedure may be used for sampling liquids of 101 kPa (14.7 psia) RVP or less in storage tanks, tank cars, tank trucks, ship, and barge tanks. 13.4.1.2 Apparatus--A typical core-type thief is shown in Fig. 3. The thief shall be designed so that a sample can be obtained within 2.0 to 2.5 cm (3/4 to 1 in.) of the bottom or at any other specificlocationwithin the tank or vessel.The size of the core thief should be selected depending upon the volume of the sample required. The thiefshould be capable of penetrating the oil in the tank to the required level, mechanically equipped to permit fallingat any desired level,
i +
0
RG. 3 Core-TypeSamplingThief
and capable of being withdrawn without undue contamination of the contents. The thief may include the following features: (a) Uniform cross section and bottom closure, (b) Extension rods for use in obtaining samples at levels corresponding with requirements for high connections or for samples to determine high settled sediment and water levels, (c) Sediment and water gage for determining the height of sediment and water in the thief, (d) A clear cylinder that facilitates observing the gravity and temperature of the oil during a gravity test; it also should be equipped with a windshield, (e) An opener to break the tension on the valve or slide at any desired level, (f) A thief cord marked so that the sample can be taken at any depth in the vertical cross section of the tank, (g) A hook to hang the thief in the hatch vertically, and (h) Sample cocks for obtaining samples for determination
i I
TABLE 5 WeightedSamplingBottle or Beaker Material
FIG. 2
I
I
I
I
Light lubdcaUng oils, kerosines, gasolines, transparent gas oils, diesel fuels, distillates Heavy lubricating oils, nontransparent gas oils Ught crude oils less than 43 cTs at 40°C Heavy crude and fuel oils
Stand Pipe (with ovedapping slots)
636
Diameter of Opening cm
in.
2
4/,
4 2 4
¾
1+/=
tt~ O 4057 13.4.2.1 ApplicationmThe bottle or beaker spot sampling procedure may be used for sampling liquids of 101 kPa (14.7 psia) RVP or less in storage tanks, tank cars, tank trucks, ship, and barge tanks. Solids or semi-liquids that can be liquified by heat may be sampled using this procedure, provided they are true liquids at the time of sampling. 13.4.2.2 Apparatus--The bottle and beaker are shown in Fig. 4. A graduated cylinder and possibly a sample container are required for use with this procedure. The sampling cage shall be made of a metal or plastic suitably constructed to hold the appropriate container. The combined apparatus shall be of such weight as to sink readily in the material to be sampled, and provision shall be made to fill the container at any desired level (see Fig. 4A). Bottles of special dimensions are required to fit a sampling cage. The use of sampling cage is generally preferred to that of a weighted sampling beaker for volatile products since loss of light ends is likely to occur when transferring the sample from a weighted sampling beaker to another container. 13.4.2.3 Procedure: (a) Inspect the sampling bottle or beaker, graduated cylinder, and sample container for cleanliness and use only clean, dry equipment. (b) Obtain an estimate of the liquid level in the tank. Use an automatic gage or obtain an outage measurement if required. (c) Attach the weighted line to the sample bottle/beaker or place the bottle in a sampling cage, as applicable. (d) Insert the cork in the sampling bottle or beaker. (e) Lower the sampling assembly to the required location. See Table 5. (f) At the required location, pull out the stopper with a sharp jerk of the sampling line. (g) Allow sufficient time for the bottle/beaker to completely fdl at the specific location. (h) Withdraw the sampling assembly. (i) Verify the bottle/beaker is completely full. If not full,
of sediment and water spaced at the 10-cm (4-in.) and 20-cm (8-in.) marker levels. (i) A graduated cylinder and sample container may also be required for use with this procedure. 13.4.1.3 Procedure: (a) Inspect the thief, graduated cylinder, and sample container for cleanliness and use only clean, dry equipment. (b) Obtain an estimate of the liquid level in the tank. Use an automatic gage or obtain an outage measurement, if required. (c) Check the thief for proper operation. (d) Open the bottom closure, and set the trip hook in the trip rod. (e) Lower the thief to the required location. See Table 5. (f) At the required location, close the bottom closure on the thief with a sharp jerk of the line. (g) Withdraw the thief. (h) If only a middle sample is required, pour all of the sample into the sample container. If samples are required at more than one location, measure out a specified amount of sample with the graduated cylinder, and deposit it in the sample container. NOTE 5--The amount of sample measured willdepend upon the size of the thiefand the tests to be performedbut should be consistentfor the samples taken at differentlevels. (i) Discard the remainder of the sample from the sampiing thief as required. (j) Repeat steps (d) through (i) to obtain a sample(s) at the other sample location(s) required by Table 5 or to obtain additional sample volume, if only a middle sample is required. (k) Install the lid on the sample container. (1) Label the sample container. (m) Return the sample container to the laboratory or other facility for mixing and testing. 13.4.2 Bottle/BeakerSpot Sampling:
/
Copper wire -handle
"•
Clove hitch
~
Eyelet
C&r Cork arrangements l-Litre (1 qt ) Sample Weighted Cage (can be fabricated to fit any size bottle)
Sheet - lead
Beaker
1-Litre (1 qt.) Weighted Beaker
A FIG. 4
Copper wire lugs
Assemblies for B o t t l e / B e a k e r S a m p l i n g
637
(~ D 4057 diameters for various applications are given in Table 5. 13.5.3 Procedure: 13.5.3.1 Inspect the sampling bottle and sample container for cleanliness and use only clean, dry equipment. 13.5.3.2 Attach the weighted line to the sample bottle, or place the bottle in a sampling cage. 13.5.3.3 If required to restrict the Idling rate, insert a notched cork in the sampling bottle. 13.5.3.4 At a uniform rate, lower the bottle assembly as near as possible to the level of the bottom of the outlet connection or swing line inlet and, without hesitation, raise it such that the bottle is approximately three-fourths full when withdrawn from the liquid. 13.5.3.5 Verify that a proper quantity of sample has been obtained. If the bottle is more than three-fourths full, discard the sample and repeat 13.5.3 and 13.5.4, adjusting the rate at which the bottle assembly is lowered and raised. Alternatively, repeat 13.5.3 and 13.5.4 using a different notched cork. 13.5.3.6 Empty the contents of the bottle into the sample container, if necessary. 13.5.3.7 If additional sample volume is required, repeat 13.5.3.3 through 13.5.3.6. 13.5.3.8 Install the lid on the sample container. 13.5.3.9 Label the sample container. 13.5.3.10 Disconnect the line from the bottle, or remove the sample bottle from the sampling cage, as applicable. 13.5.3.11 Return the sample container to the laboratory or other facility for mixing and testing. 13.6 Tap Sampling: 13.6.1 Application--The tap sampling procedure is applicable for sampling liquids of 101 kPa (14.7 psia) RVP or less in tanks that are equipped with suitable sampling taps. This procedure is recommended for volatile stocks in tanks of the breather and balloon-roof type, spheroids, and so forth. (Samples may be taken from the drain cocks of gage glasses, if the tank is not equipped with sampling taps.) 13.6.2 Apparatus: 13.6.2.1 Typical sample tap assembly is shown in Fig. 5. Each tap should be a minimum of 1.25 cm (1/2 in.) in
empty the bottle/beaker and repeat the procedure beginning with (d). (j) If only this spot sample is required for compositing will be accomplished elsewhere, pour all of the sample into the sample container or discard one-fourth of the sample, stopper the bottle/beaker, and proceed to (n). If composited samples are required at more than one location, measure out a specific amount of sample with a graduated cylinder and deposit it in the sample container. NOTE 6--The amount of sample measured will depend upon the size of the bottle/beaker and the tests to be performed but should be consistent for the samples taken at different levels. (k) Discard the remainder of the sample from the sampling bottle/beaker as required. (l) Repeat (c) through (k) to obtain a sample(s) at the other sample location(s) required by Table 5 or to obtain additional sample volume if only a middle sample is required. (m) Install the closure on the sample container. (n) Disconnect the line from the bottle, or remove the sample bottle from the sampling cage, as applicable. (o) Label the sample container. (p) Return the sample container to the laboratory or other facility for mixing and testing. 13.5 Running or All-Level Sampling: 13.5.1 Application--The running and all levels sample procedures are applicable for sampling liquids of 101 kPa (14.7 psia) RVP or less in tank cars, tank trucks, shore tanks, ship tanks, and barge tanks. Solids or semi-liquids that can be liquified by heat may be sampled by this procedure, provided they arc true liquids at the time of sampling. A running/all-levels sample is not necessarily a representative sample because the tank volume may not be proportional to the depth and because the operator may not be able to raise the sampler at the rate required for proportional filling. The rate of filling is proportional to the square root of the depth of immersion. 13.5.2 ApparatusmA suitable sampling bottle or beaker, as shown in Figs. 4A and B, equipped with notched cork or other restricted opening is required. Recommended opening
Optional-~
Optional /~/
t,
Lineor tankwall
Lineor tank wall
FIG. 5
Assemblies for Tap Sampling
638
"/Z
I~
(~@) D 4057 diameter. Taps 2.0 cm (¾-in.) may be required for heavy, viscous liquids (for example, crude oil of .9465 density (18" API) or less). On tanks that are not equipped with floating roofs, each sample tap should extend into the tank a minimum of 10 cm (4 in.). Normally, a sample tap should be equipped with a delivery tube which permits the tilling of the sample container from the bottom. 13.6.2.2 For tanks having a side outlet, a tap for obtaining a clearance sample may be located 2 cm (4 in.) below the bottom of the outlet connection. Other requirements for sample taps are outlined in Table 6. 13.6.2.3 Clean, dry glass bottles of convenient size and strength to receive the samples arc required. 13.6.3 Procedure: 13.6.3.1 Inspect the sample container(s) and graduated cylinder for cleanliness. If required, obtain clean equipment or clean the existing equipment with a suitable solvent, and rinse with the liquid to be sampled prior to proceeding to 13.6.3.2. 13.6.3.2 Obtain an estimate of the liquid level in the tank. 13.6.3.3 If the material to be sampled is 101 kPa (14.7 psia) RVP or less, connect the delivery tube directly to the sample tap as required. 13.6.3.4 Flush the sample tap and piping until they have been completely purged. 13.6.3.5 Collect the sample in a sample container or a graduated cylinder in accordance with the requirements set forth in Table 7. If samples arc to be obtained from different taps, use a graduated cylinder to measure the appropriate sample quantity. Otherwise, collect the sample directly in the sample container. If a delivery tube is used, ensure the end of the delivery tube is maintained below the liquid level in the graduated cylinder or sample container during the withdrawal of the sample. 13.6.3.6 If the sample was collected in a graduated cylinder, deposit the sample in the sample container. 13.6.3.7 Disconnect the delivery tube and cooler as applicable. 13.6.3.8 If required in accordance with Table 7, repeat 13.6.3 through 13.6.3.7 to obtain samples from additional taps. 13.6.3.9 Install the lid on the sample container. 13.6.3.10 Label the sample container. 13.6.3.11 Return the sample container to the laboratory or other facility for mixing and testing.
TABLE 7
Tank capacity less than or equal to 1590 ms (10 000 bins) Level below middle tap Level above middle tap~clos~t to middle tap Level above middle tap--closest to upper tap Level above upper tap Tank capacity greater than 1590 ma (10 000 bbls)
TABLE 6
Number of Sets Number of taps per set, min Vertical location Upper tap Lower tap Middle tap(s) Circumferential location From inlet From outlet/drain
Sampling Requirements
Total sample from the lower tap. Equalamounts from the middle and lower taps. =/s of total sample from the middle tap and 1/, of total sample from the lower tap. Equal amounts from the upper, middle, and lower taps. Equalamounts from all submerged taps. A minimum of three taps are required representlog different volumes.
is applicable for obtaining bottom samples or for obtaining samples of semi-liquids in tank cars and storage tanks. The core thiefis also widely used in sampling crude petroleum in storage tanks. In this application, it m a y be used for taking samples at different levels, as well as for bottom samples of nonmcrchantablc oil and water at the bottom of the tank. The thief can be used in some cases to obtain a quantitative estimate of the water at the bottom of a tank. 13.7.1.2 Apparatus--The thief shall be designed so that a sample can bc obtained within 2 to 2.5 c m (3/4to I in.)of the bottom of the car or tank. The core type thief is shown in Fig. 3. This type is lowered into the tank with the valve open to permit the hydrocarbon to flush through the container. W h e n the thief strikes the bottom of the tank, the valve shuts automatically to trap a bottom sample. 13.7.1.3 Procedure--Lower the clean, dry thief slowly through the dome of the tank car or tank hatch until itgently bumps the bottom. Allow the thief to filland settle,gently raise 5 to I0 c m (2 to 4 in.) and then lower the thief until it strikes the bottom and the valve closes. Remove the thief from the tank and transfer the contents to the sample container. Close and label the container immediately and deliver it to the laboratory. 13.7.2 Closed-Core Bottom Sampling." 13.7.2.1 Application--The closed-corcthiefsampling procedurc is applicable for obtaining bottom samples of tank cars and storage tanks. In sampling crude petroleum in storage tanks, the thief might be used for obtaining bottom samples of nonmcrchantable oil and water at the bottom of the tank. 13.7.2.2 Apparatus--The thief shall be designed so that a sample can be obtained within 1.25 c m (I/2in.) of the bottom of the tank car or tank. A closed-core type thief is shown in Fig. 6. This type of thief has a projecting stem on the valve rod which opens the valves automatically as the stem strikes the bottom of the tank. The sample enters the container through the bottom valve, and air is released simultaneously through the top valve. The valves snap shut when the thief is withdrawn. Use only clean, dry cans, or glass bottles as sample containers. 13.7.2.3 Procedure--Lower the clean, dry thief through the dome of the tank car or tank hatch until it strikes the bottom. W h e n full, remove the thief and transfer the contents to the sample container. Close and label the container immediately and deliver it to the laboratory. 13.7.3 Extended- Tube Sampling:
13.7 Bottom Sampling: 13.7.1 Core Thief Bottom Sampling: 13.7.1.1 Application--The core thief sampling procedure
Tank Capadty
Tap Sampling Requirements
Tank Capactty/Uquld Level
Sample Tap Specifications 1590 ma (10 000 10his) Greater Than 1590 ma Or Less (10 000 bbls) 1 2A 3 5 45 cm (18 in.) from top of shell even with bottom of outlet equally spaced between upper and lower tap 2.4 m (8 ft), min 1.5 m (6 ft), min
A The respective sets of taps should be located on opposite sides of the tank.
639
~
'.
D 4057 manually operated pump. For support purposes and to establish a known sampling point, the tubing is attached to the weighted end of a conductive wire or tape such that the open end of the tube is located approximately 1.25 cm (V2 in.) above the rip of the weight. The tubing and wire (or tape) shall be long enough to extend to the bottom (reference height) of the vessel or storage tank from which the sample is to be obtained. A grounding cable shall be provided for the assembly. In addition to the sampler, a clean, dry bottle or other appropriate container is required to collect each sample. 13.7.3.3 Procedure." (a) Assemble the extended-tube sampler. (b) Following assembly, prime the tubing and pump with water and close-off (ensure it is not vented to atmosphere) the top end of the assembly to prevent loss of priming water as the sampling tube is lowered. Connect the grounding cable to the ship or barge tank or storage tank, and lower the weighted end of the sampler to the bottom. (c) Begin the sampling operation by slowly and steadily operating the manual pump. To reduce the possibility of capturing a contaminated sample, initially purge and discard a volume greater than twice the sampling assembly's capacity. Collect the sample(s) directly in a clean, dry bottle(s) or other appropriate container(s). (d) If a sample at a different level within the bottom water layer is required, raise the weighted bob and tubing to the new level above the bottom. Purge the residual water in the tubing assembly (twice the sampler assembly volume), and collect the new sample(s). (e) After each sample has been collected, immediately close and label the bottle (or container) in preparation for delivery to the laboratory. (f) When the sampling operation is complete, clean and disassemble the sampler components.
Line for lowering
I I I I I I I I I I I I I I I I I I I I I
I
I I
I I
t
I
I
I
" ",
4 lugs
I FIG. 6
Closed-Core Type Sampling Thief
13.7.3.1 ApplicationmThe extended-tube sampling procedure may be used only for obtaining bottom water samples primarily on ships and barges. The procedure may be used for sampling bottom water in shore tanks, but no specific guidelines for such use are available. 13.7.3.2 Apparatus~A typical extended-tube sampling assembly is shown in Fig. 7. The extended-tube sampler consists of a flexible tube connected to the suction of a
14. Manual Pipeline Sampling 14.1 Application--This manual pipeline sampling procedure is applicable to liquids of 101 kPa (14.7 psia) RVP or less and semi-liquids in pipelines, filling lines, and transfer lines. The continual sampling of pipeline streams by automarie devices is covered in Practice D 4177. When custody transfer is involved, continuous automatic sampling is the preferred method as opposed to manual pipeline samples. In the event of automatic sampler failure, manual sampling may be needed. Such manual samples should be taken as representatively as possible. 14.2 ApparatusmA sampling probe is used to direct sample from the flowing stream. All probes should extend into the center one-third of the pipe's cross-section area. All probes inlets should be facing upstream. Probe designs that are commonly used are shown in Fig. 8 and can be: 14.2.1 A tube beveled at a 45* angle as shown in Fig. 8A. 14.2.2 A short radius elbow or pipe bend. The end of the probe should be chamfered on the inside diameter to give a sharp entrance edge (see Fig. 8B). 14.2.3 A closed-end tube with a round orifice spaced near the closed end as shown in Fig. 8C. 14.3 ProbeLocation: 14.3.1 Since the fluid to be sampled may not always be homogeneous, the location, position, and size of the sam-
Manual sampling pump
Sampling tube
Support wire or tape - -
Weight Ill
J
FIG. 7
Typical Extended-Tube Sampler
640
i~
D 4057
End of probe closed orifice facing upstream 6.4 mm - 5 cm (1/4"-2") pipe o r tubing \ 1 Manufacturers "~1[ ~ I [ standard
6.4 mm - 5 cm (1/4"-2") pipe or tubing 45" Bevel
To a,ve A
~
To valve
/6.4
~
mm-5cm (1/4" -2") pipe or tubing
,H-~ . To valve
B
NOTE--Probesmay be fitted withvalvesor plug cocks. The probeshouldbe orientedhorizontally. FIG. 8 Probesfor Spot Manual SampleB
piing probe should be such as to minimize any separation of water and heavier particles that would make their concentration different in the gathered sample than in the main stream. 14.3.2 The probe should always be in a horizontal plane to prevent drain back of any part of the sample to the main stream. 14.3.3 The sampling probe should preferably be located in a vertical run of pipe where such a vertical run can be provided. The probe may also be located in a horizontal run of pipe. The flowing velocity must be high enough to provide adequate turbulent mixing (see Practice D 4177). 14.3.4 Where adequate flowing velocity is not available, a suitable device for mixing the fluid flow should be installed upstream of the sampling tap to reduce stratification to an acceptable level. If flow has been vertical for a sufficient distance, as in a platform riser, such a device may not be necessary even at low flow rates. Some effective methods for obtaining adequate mixing are: a reduction in pipe size, a series of baffles, and orifice or perforated plate, or combination of any of these methods. The design or sizing of the device is optional with the user, as long as the flowing stream is sufficiently well mixed to provide a representative sample from the probe. 14.3.5 Sampling lines, used in conjunction with probes, should be as short as is practical and should be cleared before any samples are taken. 14.3.6 When sampling semi-liquids, it may be necessary to heat the sample line, valves, and receiver to a temperature just sufficient to keep the material liquid and to ensure accurate sampling and mixing. 14.3.7 To control the rate at which the sample is withdrawn, the probe should be fitted with valves or plug cocks. 14.4 Procedure: 14.4.1 Adjust the valve or plug cock from the sampling probe so that a steady stream is drawn from the probe. Whenever possible, the rate of sample withdrawal should be such that the velocity of liquid flowing through the probe is approximately equal to the average linear velocity of the stream flowing through the pipeline. Measure and record the rate of sample withdrawal as gallons per hour. Divert the sample stream to the sampling container continuously or intermittently to provide a quantity of sample that will be of sufficient size for analysis.
14.4.2 In sampling crude petroleum and other petroleum products, samples of 250 mL (1/2pt) or more should be taken every hour or at increments less than an hour, as necessary. By mutual agreement, the sample period or sample size, or both, may be varied to accommodate the parcel size. It is important that the size of the samples and the intervals between the sampling operations be uniform for a uniform flow rate. When the main stream flow rate is variable, the sampling rate and volume must be varied accordingly so that the flow is proportional. In practice, this is difficult to accomplish manually. 14.4.3 Each sample of crude petroleum should be placed in a closed container, and at the end of the agreed upon time period, the combined samples should be mixed and a composite sample taken for test purposes. Refer to 12.3 for mixing and handling. The sample container should be stored in a cool, dry place; exposure to direct sunlight should be avoided. 14.4.4 Alternatively, line samples may be taken at regular intervals and individually tested. The individual test results may be arithmetically averaged, adjusting for variations in flow rate during the agreed upon time period. 14.4.5 Either composite or arithmetically averaged results are acceptable by mutual agreement. 14.4.6 With either procedure, always label each sample and deliver to the laboratory in the container in which it was collected.
15. Dipper Sampling 15.1 Application--The dipper sampling procedure is applicable for sampling liquids of 13.8 kPa (2 psia) RVP or less and semi-liquids where a free or open discharge stream exists, as in small filling and transfer pipelines, 5 cm (2 in.) in diameter or less, and filling apparatus for barrels, packages, and cans. 15.2 Apparatus--Use a dipper with a flared bowl and a handle of conventional length made of a material such as tinned steel that will not affect the product being tested. The dipper should have a capacity suitable for the amount to be collected and must be protected from dust and dirt when not being used. Use a clean, dry sample container of the desired size. 15.3 Procedure--Insert the dipper in the free-flowing stream so that a portion is collected from the full cross 641
~) D 4057 section of the stream. Take portions at time intervals chosen so that a complete sample proportional to the pumped quantity is collected. The gross amount of sample collected should be approximately 0.1 percent, but not more than 150 L (40 gal) of the total quantity being sampled. Transfer the portions into the sample container as soon as they are collected. Keep the container closed, except when pouring a dipper portion into it. As soon as all portions of the sample have been collected, close and label the sample container and deliver it to the laboratory.
16. Tube Sampfing 16.1 Application--The tube sampling procedure is applicable for sampling liquids of 13.8 kPa (2 psia) RVP or less and semi-liquids in drums, barrels, and cans. 16.2 Apparatus--Either a glass or metal tube may be used, designed so that it will reach to within about 3 mm (I/8 in.) of the bottom of the container. Capacity of the tube can vary from 500 mL to 1 L (1 pt to 1 qt). A metal tube suitable for sampling 189 L (50-gal) drums is shown in Fig. 9. Two rings soldered to opposite sides of the tube at the upper end are convenient for holding it by slipping two fingers through the rings, thus leaving the thumb free to close the opening. Use clean, dry cans, or glass bottles for sample containers. 16.3 Procedure: 16.3.1 Place the drum or barrel on its side with the bung up. If the drum does not have a side bung, stand it upright and sample from the top. If detection of water, rust, or other insoluble contaminants is desired, let the barrel or drum remain in this position long enough to permit the contami-
FIG. 9
Typical Drum or Barrel Sampler
nants to settle. Remove the bung and place it beside the bung hole with the oily side up. Close the upper end of the clean, dry sampling tube with the thumb, and lower the tube into the oil to a depth of about 30 cm (1 ft). Remove the thumb, allowing oil to flow into the tube. Again, close the upper end with the thumb and withdraw the tube. Rinse the tube with the oil by holding it nearly horizontal and turning it so that the oil comes in contact with that part of the inside surface that will be immersed when the sample is taken. Avoid handling any part of the tube that will be immersed in the oil during the sampling operation. Discard the rinse oil and allow the tube to drain. Insert the tube into the oil again, holding the thumb against the upper end. (If an all-levels sample is desired, insert the tube with the upper end open.) When the tube reaches the bottom, remove the thumb and allow the tube to fill. Replace the thumb, withdraw the tube quickly, and transfer the contents to the sample container. Do not allow the hands to come in contact with any part of the sample. Close the sample container; replace and tighten the bung in the drum or barrel. Label the sample container and deliver it to the laboratory. 16.3.2 Obtain samples from cans of 18.9 L (5 gal) capacity or larger in the same manner as for drums and barrels, using a tube of proportionately smaller dimensions. For cans of less than a 18.9-L (5-gal) capacity, use the entire contents as the sample, selecting cans at random as indicated in Table 4 or in accordance with the agreement between the purchaser and the seller. 17. Boring Sampling 17.1 Application--The boring sampling procedure is applicable for sampling waxes and soft solids in barrels, cases, bags, and cakes when they cannot be melted and sampled as liquids. 17.2 Apparatus: 17.2.1 Use a ship auger 2 cm (3/4 in.) in diameter (preferred), similar to that shown in Fig. 10, and of sufficient length to pass through the material to be sampled. 17.2.2 Use clean, wide-mouth metal containers or glass jars with covers for cover sample containers. 17.3 Procedure--Remove the heads or covers of barrels or cases. Open bags and wrappings of cakes. Remove any dirt, sticks, string, or other foreign substances from the surface of the material. Bore three test holes through the body of the material, one at the center, the other two halfway between the center and the edge of the package on the right and left sides, respectively. If any foreign matter is removed from the interior of the material during the boring operation, include it as part of the borings. Put the three sets of borings in
FIG. 10 Ship Auger for Boring Procedure
642
ql~) O 4 0 5 7 .q-
individual sample containers, label, and deliver them to the laboratory. 17.4 Laboratory Inspection--If there are any visible differences in the samples, examine and test each set of borings at the laboratory. Otherwise, combine the three sets of borings into one sample. If subdivision of borings is desired, chill, pulverize (if necessary), mix, and quarter the borings until reduced to the desired amount.
18. Grab Sampling 18.1 ApplicationmThe grab sampling procedure is applicable for sampling all lumpy solids in bins, bunkers, freight cars, barrels, bags, boxes, and conveyors. It is particularly applicable for the collection of green petroleum coke samples from railroad cars and for the preparation of such samples for laboratory analysis. Refer to Practice D 346 when other methods of shipping or handling are used. Petroleum coke may be sampled while being loaded into railroad cars from piles or after being loaded into railroad cars from coking drums. 18.2 Apparatus--A polyethylene pail of approximately 9.5 L (10 qt) capacity shall be used as the sample container. Use a stainless steel or aluminum No. 2 size scoop to fill the container. 18.3 Procedure--Lumpy solids are usually heterogeneous and difficult to sample accurately. It is preferable to take samples during the unloading of cars or during transit; obtain a number of portions at frequent and regular intervals and combine them. 18.3.1 Sampling From Railroad Cars--Use one of the following procedures: 18.3.1.1 Cars Being Loaded from a Pile--Take a full scoop of sample at each of the five sampling points shown in Fig. 11, and deposit in a polyethylene pail. Cover the sample, and deliver it to the laboratory. Each sampling point shall be located equidistant from the sides of the railroad car. 18.3.1.2 After Direct Loading from Coking DrumsuAt any five of the sampling points shown in Fig. 12, take a full scoop of coke from about 30 em (1 ft) below the surface, and deposit it in a polyethylene pail. Cover the sample and deliver it to the laboratory. 18.3.2 Sampling From Conveyors--Take one scoop for each 7 to 9 metric tons (8 to 10 short tons) of coke transported. These samples may be handled separately or composited after all samples representing the lot have been taken. 18.3.3 Sampling From Bags, Barrels, or Boxes:
o--
O0 FIG. 11
•
/.=lengthofcar /
L_
L_
L
L~
L
L ~
L
LL
L
"5
FIG. 12 Location of Sampling Points from Exposed Surface for Rail Cars
18.3.3.1 Obtain portions from a number of packages selected at random as shown in Table 3, or in accordance with the agreement between the purchaser and seller. 18.3.3.2 Carefully mix the grab sample and reduce it in size to a convenient laboratory sample by the quartering procedure described in Practice D 346. Perform the quartering operation on a hard, clean surface, free from cracks, and protected from rain, snow, wind, and sun. Avoid contamination with cinders, sand, chips from the floor, or any other material. Protect the sample from loss or gain of moisture or dust. Mix and spread the sample in a circular layer, and divide it into quadrants. Combine two opposite quadrants to form a representative reduced sample. If this sample is still too large for laboratory purposes, repeat the quartering operation. In this manner, the sample will finally be reduced to a representative, suitable size for laboratory purposes. Label and deliver the sample to the laboratory in a suitable container.
19. Grease Sampling 19.1 Application--This method covers practices for obtaining samples representative of production lots or shipmerits of lubricating greases or of soft waxes or soft bitumens similar to grease in consistency. This procedure is quite general because a wide variety of conditions are often encountered, and the procedure may have to be modified to meet individual specifications. Proceed in accordance with Sections 6 and 7, particularly those paragraphs pertaining to precautions, care and cleanliness, except where they conflict with instructions given in this section. 19.2 Inspection: 19.2.1 If the material is a lubricating grease and inspection is made at the manufacturing plant, take samples from finished shipping containers of each production batch or lot. Never take grease samples directly from grease kettles, cooling pans, tanks, or processing equipment. Do not sample the grease until it has cooled to a temperature not more than 9.4"C (15 *F) above that of the air surrounding the containers and until it has been in the finished containers for at least 12 h. When the containers for a production batch of grease are of different sizes, treat the grease in each size of container as a separate lot. When inspection is made at the place of delivery, obtain a sample from each shipment. If a shipment consists of containers from more than one production batch (lot numbers), sample each batch separately. 19.2.2 If the material being inspected is of grease-like consistency, but is not actually a lubricating grease but some mixture of heavy hydrocarbons, such as microcrystalline
~__~_~__t :~
O0 Location of Sampling Points at Different Levels for Rail Cars
643
fl~) D 4 0 5 7
sufficient quantity to provide a composite sample of the desired quantity (see Table 8). Withdraw portions with a clean scoop, large spoon, or spatula, and place them in a clean container. Very soft, semi-fluid greases may be sampled by dipping with a 0.45 kg (1 lb) can or suitable dipper. If any marked difference in the grease from the various locations of an opened container is found, take two separate samples of about 0.45 kg (1 lb) each, one from the top surface adjacent to the wall and the other from the center of the container, at least 15 cm (6 in.) below the top surface. If any marked variations are noted between different containers of a lot or shipment, take separate samples of about 0.45 (1 lb) from each container. When more than one sample of a batch or shipment is taken because of lack of uniformity, send them to the laboratory as separate samples. 19.4.3 If more than one portion is required to represent a lot or shipment of grease softer than 175 penetration (see Test Method D 217), prepare a composite sample by mixing equal portions thoroughly. Use a large spoon or spatula and a clean container. Avoid vigorous mixing or working of air into the grease. As grease samples become partially "worked" in being removed from containers, the procedure is not suitable for obtaining samples of greases softer than 175 penetration on which unworked penetration is to be determined. For greases having a penetration ofless than 175, cut samples from each container with a knife in the form of blocks about 15 by 15 by 5 em (6 by 6 by 2 in.). If required, make unworked penetration tests on blocks as procured and other inspection tests on grease cut from the blocks.
waxes or soft bitumens, it is permissible to take samples from pans, tanks, or other processing equipment, as well as from containers of the finished product. The grease sampling method shall be applicable to such stocks only if for some reason it is not possible to apply heat and convert the material into a true liquid. 19.3 Sample Size--Select containers at random from each lot or shipment to give the required quantity speeitied in Table 8. 19.4 Procedure." 19.4.1 Examine the opened containers to determine whether the grease is homogeneous, comparing the grease nearest the outer surfaces of the container with that in the center, at least 15 cm (6 in.) below the top surface, for texture and consistency. When more than one container of a lot or shipment is opened, compare the grease in all open containers. 19.4.2 If no marked difference in the grease is found, take one portion from the approximate center and at least 7.5 cm (3 in.) below the surface of each opened container in TABLE 8 Size of Grease Samples Lot or Shipment
Container Tubes or packages, less than 0.45 Kg (1 Ib) 0.45 Kg (1 Ib) cans 2.3 or 4.6 Kg (5 or 10 Ib) cans Larger than 4.6 Kg (10 Ib)
All All All less than 4536 Kg (10 000 Ib)
Larger than 4.6 Kg (10 Ib)
4536 to 22 680 Kg (10 000 to 50 000 Ib)
Larger than 4.6 Kg (10 Ib)
more than 22 680 Kg (50 000 Ib)
Minimum Sample enough units for a 4.4 Kg (2 Ib) sample three cans one can 1 to 1.4 Kg (2 to 3 Ib) from one or more containers 1 to 2.3 Kg (2 to 5 Ib) fl'om two or more contednors 1 to 2.3 Kg (2 to 5 Ib) from three or more contoJners
20. Keywords 20.1 boring sampling; bottle/beaker sampling; core thief spot sampling; dipper sampfing; extended tube sampling; grab sampling; grease sampling; marine custody transfer; sample containers; sample handling; sample labeling; sample mixing; sample shipment; sampling; sampling cage; static sampling; stand pipes;tap sampling; tube sampling
ANNEX
(Mandatory Information) A1. PRECAUTIONARY STATEMENTS A I.I The following substances may be used throughout the course of this standard test method. The precautionary statements should be read prior to use of such substances. A I.I.I Benzene:
A I.I.I.I Keep away from heat, sparks, and open flame. AI.I.I.2 Keep container closed. A I.I.1.3 Use with adequate ventilation. AI.I.I.4 Use fume hood whenever possible. AI.I.I.5 Avoid build-up of vapors and criminate all sources of ignition,especiallynon-explosion proof electrical apparatus and heaters. AI.I.I.6 Avoid prolonged breathing of vapors or spray mist. AI.I.I.7 Avoid contact with skin and eyes. D o not take internally. A 1.1.2 Diluent (Naphtha): 644
Al.I.2.1 Keep away from heat, sparks, and open flame. A 1.1.2.2 Keep container dosed. Al. 1.2.3 Use with adequate ventilation. Avoid build-up of vapors and eliminate all sources of ignition, especially non-explosion proof electrical apparatus and heaters. A1.1.2.4 Avoid prolonged breathing of vapors or spray mist. A1.1.2.5 Avoid prolonged or repeated skin contact. Al.I.3 Flammable Liquid (general): A 1.1.3.1 Keep away from heat, sparks, and open flame. AI. 1.3.2 Keep container dosed. A 1.1.3.3 Use only with adequate ventilation. A1.1.3.4 Avoid prolonged breathing of vapor or spray mist. Al. 1.3.5 Avoid prolonged or repeated contact with skin. A1.1.4 Gasoline (White):
(1~ D 4057 AI. 1.4.6 Avoid prolonged or repeated skin contact. A 1.1.5 Toluene and Xylene: AI. 1.5.1 Warning--Flammable. Vapor harmful. A1.1.5.2 Keep away from heat, sparks, and open flame. AI.1.5.3 Keep container dosed. A1.1.5.4 Use with adequate ventilation. Avoid breathing of vapor or spray mist. A1.1.5.5 Avoid prolonged or repeated contact with skin.
A 1.1.4.1 Harmful if absorbed through skin. A1.1.4.2 Keep away from heat, sparks, and open flame. A1.1.4.3 Keep container closed. Use with adequate ventilation. A1.1.4.4 Avoid build-up of vapors and eliminate all sources of ignition especially non-explosion proof electrical apparatus and heaters. A1.1.4.5 Avoid prolonged breathing of vapor or spray mist.
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted In connection with any item mentioned in this standard. Users of this standard are expre~ly advised that determination of the valMity of any such patent rights, and the risk of Infringement of such rights, are entirely their own responsibility. This standard Is subject to revision at any time by the responsible technical committee and mum be reviewed every five years and ff not revised, either reepproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive Cereful consideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received s fair hearing you should make your views known to the ASTM Committee on Standards, 100 Borr Harbor Drive, West Conshohocken, PA 19428.
645
Designation: D 4177 - 95
An American National Standard
Designation: MPMS Chapter 8.2
Standard Practice for Automatic Sampling of Petroleum and Petroleum Products I This standard is issued under the fixed designation D 4177; the number immediately following the designation indicates the year of ori~nal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsllon (0 indicates an editorial change since the last revision or rcapproval.
This standard has been approved for use by agencies of the Department of Defense. Consult the DoD Index of Specifications and Standards for the specific year of issue which has been adopted by the Department of Defense. This practice has been approved by the sponsoring committees and accepted by the cooperating organizations in accordance with established procedures.
1. Scope 1.1 This practice covers information for the design, installation, testing, and operation of automated equipment for the extraction of representative samples of petroleum and petroleum products from a flowing stream and storing them in a sample receiver. If sampling is for the precise determination of volatility, use Practice D 5842 in conjunction with this practice. For sample mixing, refer to Practice D 5854. Petroleum products covered in this practice are considered to be a single phase and exhibit Newtonian characteristics at the point of sampling. 1.2 Applicable Fluids--This practice is applicable to petroleum and petroleum products with vapor pressures at sampling and storage temperatures less than or equal to 101 kPa (14.7 psi). Refer to D 5842 when sampling for Reid vapor pressure (RVP) determination. 1.3 Non-applicable Fluids--Petroleum products whose vapor pressure at sampling and sample storage conditions are above 101 kPa (14.7 psi) and liquified gases (that is, LNG, LPG etc.) are not covered by this practice. 1.3.1 While the procedures covered by this practice will produce a representative sample of the flowing liquid into the sample receiver, specialized sample handling may be necessary to maintain sample integrity of more volatile materials at high temperatures or extended residence time in the receiver. Such handling requirements are not within the scope of this practice. Procedures for sampling these fluids are described in Practice D 1265, Test Method D 1145, and GPA 2166. 1.4 Annex A2 contains theoretical calculations for selecting the sampler location. Annex A3 lists acceptance methodologies for sampling systems and components. Annex A4 gives performance criteria for permanent installations, while Annex A5 has the criteria for portable sampling units. Appendix X1 is a design data sheet for automatic sampling systems; Appendix X2 compares the percent sediment and water to unloading time period. i This practice is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee 1302.02 on Static Petroleum Measurement. Current edition approved Nov. 10, 1995. Published January 1996. Originally published as D 4177 - 82. Last previous edition D 4177 - 82 (1990)*l.
1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 2. Referenced Documents 2.1 A S T M Standards: D923 Test Method for Sampling Electrical Insulating Liquids 2 D 1145 Test Method for Sampling Natural Gas 3 D 1265 Practice for Sampling Liquified Petroleum (LP) Gases--Manual Method 4 D4057 Manual Sampling of Petroleum and Petroleum Products 5 D4928 Test Method for Water in Crude Oils by Coulometric Karl Fischer Titration 6 D 5842 Practice for Sampling and Handling of Fuels for Volatility Measurements 6 D5854 Practice for Mixing and Handling of Liquid Samples of Petroleum and Petroleum Products 6 2.2 API Standards:7 API Manual of Petroleum Measurement Standards, Chapter 3 API Manual of Petroleum Measurement Standards, Chapter 4 API Manual of Petroleum Measurement Standards, Chapter 5 API Manual of Petroleum Measurement Standards, Chapter 6 API Manual of Petroleum Measurement Standards, Chapter 10 2.3 Gas Processors Association Standard..s GPA 2166 Obtaining Natural Gas Samples for Analysis by Gas Chromatography 2 Annual Book of ASTM Standards, Vol 10.03. 3 Annual Book of ASTM Standards, Vol 05.05. 4 Annual Book of ASTM Standards, Vol 05.01. 5 Annual Book of ASTM Standards, Vol 05.02. 6 Annual Book of ASTM Standards, Vol 05.03. Available from American Petroleum Institute, 1220 L St., NW, Washington, DC 20005. s Available from Gas Processors Assoc., 6526 E. 60th St., Tulsa, OK 14145.
646
~
D 4177
2.4 Institute of Petroleum Standard."9 IP Petroleum Measurement Manual, Part IV, Sampling Section 2, Guide to Automatic Sampling of Liquids from Pipelines, Appendix B, 34th Ed 2.5 Government Standard: ~° CFR 29, Section 11910.1000
3. Terminology 3.1 Description of Terms Specific to This Standard." 3.1.1 automatic sampler, n ~ a device used to extract a representative sample from the liquid flowing in a pipe. 3.1.1.1 Discussion--The automatic sampler usually consists of a probe, a sample extractor, an associated controller, a flow measuring device, and a sample receiver. 3.1.2 automatic sampling system, n ~ a system consisting of stream conditioning, an automatic sampler, and sample mixing and handling. 3.1.3 dissolved water, nDwater in solution in petroleum and petroleum products. 3.1.4 emulsion, n ~ a water in oil mixture, which does not readily separate. 3.1.5 entrained water, n--water suspended in the oil. 3.1.5.1 Discussion--Entrained water includes emulsions but does not include dissolved water. 3.1.6 flow proportional sample, n--flow taken such that the rate is proportional throughout the sampling period to the flow rate of liquid in the pipe. 3.1.7 free water, n--water that exists as a separate phase. 3.1.8 grab, n--the volume of sample extracted from a pipeline by a single actuation of the sample extractor. 3.1.9 homogeneous, adj~when liquid composition is the same at all points in the container, tank, or pipeline cross section. 3.1.10 isokinetic sampling, nDsampling in such a manner that the linear velocity through the opening of the sample probe is equal to the linear velocity in the pipeline at the sampling location and is in the same direction as the bulk of the liquid approaching the sampling probe. 3.1.11 Newtonian fluid, n ~ a liquid whose viscosity is unaffected by the order of magnitude or agitation to which it may be subjected as long as the temperature is constant. 3.1.12 power mixer, n--a device which uses an external source of power to achieve stream conditioning. 3.1.13 primary sample receiver/container, n--a vessel into which all samples are initially collected. 3.1.14 probe, n--the portion of the automatic sampler that extends into the pipe and directs a portion of the fluid to the sample extractor. 3.1.15 profile testing, n--a procedure for simultaneously sampling at several points across the diameter of a pipe to identify the extent of stratification. 3.1.16 representative sample, n--a portion extracted from a total volume that contains the constituents in the same proportions as are present in the total volume. 3.1.17 sample, n--a portion extracted from a total volume that may or may not contain the constituents in the 9 Available from The Institute of Petroleum, 61 New Cavendish St., London WIM BAR, England. ~oAvailable from Supt. of Documents, U,S. Government Printing Office, Washington, DC 20402.
same proportions as are present in that total volume. 3.1.18 sample controller, nma device which governs the operation of the sample extractor. 3.1.19 sample extractor, n n a device which removes a sample (grab) from a pipeline, sample loop, or tank. 3.1.20 sample handling and mixing, n n t h e conditioning, transferring and transporting of a sample. 3.1.21 sample loop (fast loop or slip stream), n m a low volume bypass diverted from the main pipeline. 3.1.22 sampling, nDall the steps required to obtain a sample that is representative of the contents of any pipe, tank, or other vessel and to place that sample into a container from which a representative test specimen can be taken for analysis. 3.1.23 sampling system proving, n--a procedure used to validate an automatic sampling system. 3.1.24 sediment and water (S&W), n--material which coexists with, but is foreign to, a petroleum liquid. 3.1.24.1 DiscussionDS&W may include dissolved water, free water and sediment, and emulsified and entrained water and sediment. 3.1.25 static mixer, n--a device which utilizes the kinetic energy of the flowing fluid to achieve stream conditioning. 3.1.26 stream condition, n--the distribution and dispersion of the pipeline contents, upstream of the sampling location. 3.1.27 stream conditioning, n--the mixing of a flowing stream so that a representative sample can be extracted. 3.1.28 time proportional sample, n ~ a sample composed of equal volume grabs taken from a pipeline at uniform time intervals during the entire transfer. 3.1.29 worst case conditions, n ~ t h e operating conditions for the sampler that represent the most uneven and unstable concentration prot'de at the sampling location.
4. Significance and Use 4.1 Representative samples of petroleum and petroleum products are required for the determination of chemical and physical properties, which are used to establish standard volumes, prices, and compliance with commercial and regulatory specifications.
5. Representative Sampling Criteria 5.1 The following criteria must be satisfied to obtain a representative sample from a flowing stream. 5.1.1 For non-homogeneous mixtures of oil and water, free and entrained water must be uniformly dispersed at the sample point. 5.1.2 Grabs must be extracted and collected in a flow proportional manner that provides a representative sample of the entire parcel volume. 5.1.3 Grabs must be a consistent volume. 5.1.4 The sample must be maintained in the sample receiver without altering the sample composition. Venting of hydrocarbon vapors during receiver filling and storage must be minimized. Samples must be mixed and handled to ensure a representative test specimen is delivered into the analytical apparatus.
6. Automatic Sampling Systems 6.1 An automatic sampling system consists of stream 647
(@) D 4177 Sample grab discharge (in downward sloping line) Flow I
Probe ,r----
~ [ ~
~
Sample receiver (insulate and heat ontrol~er_,~ if necessary) ........
=
Flow
Flow signal
Sample grab discharge (in downward / sloping line) ]l /~---~ Sample receiver ~1 ( ~ "(insulate and heat ~L ~ Controller if necessary)
!
--IN-Sample extractor
Sample extractor and probe indicator Automatic SampIIng-ln-Line
Automatic Sampling With a Fast Loop
NOTEgArrow does not indicatepipingorientation. FIG. 1
Typical Automatic Sampling Systems
conditioning upstream of the sampling location, a device to physically extract a grab from the flowing stream, a flow measurement device for flow proportioning, a means to control the total volume of sample extracted, a sample receiver to collect and store the grabs and, depending on the system, a sample receiver/mixing system. Unique properties of the petroleum or petroleum product(s) being sampled may require the individual components or the entire system be insulated or heated, or both. Appendix X 1 references many of the design consideration that should be taken into account. 6.2 Grabs must be taken in proportion to flow. However, if the flow rate, during the total parcel delivery (week, month, etc.) varies less than +10 % from the average flow rate, a representative sample may be obtained by the time proportional control of the grabs. 6.3 There are two types of automatic sampling systems (see Fig. 1). Both systems can produce representative samples if properly designed and operated. One system locates the extracting device directly in the main line, whereas the other system locates the extracting device in a sample loop. 6.4 In a sample loop type system, a probe is located in the main pipeline and directs a portion of the fluid flow into the sample loop. This probe may be a 90 ° elbow or a 45 ° level facing upstream (see 10.2). The average flow velocity through the sample loop shall be near the maximum average velocity expected in the main pipeline, but not less than 2.5 m/s (8 ft/s). 6.5 The controller which operates the sample extractor in the sample loop receives its flow proportional signal from the flow meter(s) in the main line. For sample loop installations, a flow indicator must also be installed in the sample loop. 6.6 If circulation in the sample loop stops and sampling continues, a non-representative sample will result. A lowflow alarm should be installed to alert the operator of a loss of flow. In no case shall a filter be installed in a sample loop, upstream of the sample extractor, as it may alter the representativeness of the sample.
7. Sampling Frequency 7.1 Guidelines for sampling frequency can be given in 648
terms of "grab per lineal distance of pipeline volume." For marine and pipeline service this minimum guideline can be related to barrels per grab using the following equation: BBL/grab = .0001233 × i)2 or .079548 x d2 (1) where: D -- nominal pipe diameter, mm and d = nominal pipe diameter, in. 7.2 This formula equates to one grab for every 25 lineal metres (approximately 80 ft) of pipeline volume. 7.3 Sampling frequency should be based on maximizing grabs for the available receiver size. Typically, Lease Automatic Custody Transfer (LACT) or Automatic Custody Transfer (ACT) units are paced at one grab per one to ten barrels. 7.4 The optimum sampling frequency is the maximum number of grabs which may be obtained from any parcel operating within the grab frequency and grab volume limitations of the equipment. The completed sample should be of sufficient volume to mix and properly analyze while not over filling the sample receiver.
8. Stream Conditioning 8.1 The sampler probe must be located at a point in the pipe where the flowing stream is properly conditioned. This conditioning may be accomplished with adequate flow velocity through the piping system or mixing elements may be added to supplement mixing provided by the basic piping. Petroleum that contains free or entrained sediment and water (S&W) requires adequate mixing energy to create a homogeneous mixture at the sample point. 8.2 Petroleum products are generally homogeneous and usually require no special stream conditioning. Exceptions to this may occur if free water is present or if a product is exiting a blending system. 8.3 Velocities and Mixing Elements: 8.3.1 Figure 2, based on tests, provides a guideline for minimum velocities versus mixing elements for pipes 50 mm (2 in.) in diameter and larger. Stream conditioning can be accomplished with pressure reducing valves, metering manifolds, lengths of reduced diameter piping, or piping elements
~ Mixing Element Power mixing
D 4177 Minimum Pipeline Velocity. meters per second .91 1.22 1.52 1.83
Piping Horizontal or vertical
0
Static mixing
Vertical
Stratified
Static mixing
Horizontal
Stratified
Not predictable
Piping elements
Vertical
Stratified
Not pred ctab e
Piping elements
Horizontal
Stratified
None
Horizontal or vertical
.305
.61
2.44
Adequate at an}' velocity Not Pred ctable Adequately dispersed Adequately dispersed Adequately dispersed Not predictable
Stratified or not predictable 0 1 2
3 Minimum
FIG. 2
9. Special Considerations for Marine Applications 9.1 When pumping from a shore tank or from a vessel, a significant amount of free water may be transferred during a short period of time (see Appendix X2). This may occur when the pumping rate is low and the oil/water mixture is stratified. The stream conditioning may not be adequate to provide a representative sample. To help minimize this condition, a tank that does not contain free water should be utilized first. Tanks containing free water can be discharged when the pumping rate is normal. 9.2 If the sampler is located some distance from the point of load/discharge, operating procedures should account for the line fill between those two points. 10. Probes 10.1 Probe Location and Installation: 10.1.1 The recommended sampling area is approximately the center one-third of the pipeline cross-section area as shown in Fig. 3. 10.1.2 The probe opening must face upstream and the external body of the probe should be marked with the Typical Receiver Sizes
Lease automaticcustody transfer Pipelines (crude petroleum) Pipelines (products) Portable sampler Tanker loading/unloading
Adequately dispersed
4 5 6 Pipeline Velocity, feet per second
7
S
General Guidelines for Minimum Velocities Versus Mixing Elements
(valves, elbows, tees,piping, or expansion loops). 8.3.2 Where the flow velocity at the automatic sampler probe location fallsbelow the m i n i m u m levels detailed in Table I, additional means will be required to provide adequate stream conditioning such as power mixers or static mixers. The effect of viscosity, density, water content, as well as the relative position of the mixing element(s) and sample probe should also be considered. 8.3.3 Specific calculation procedures for estimating the acceptability of a proposed or existing sampling location are detailed in Annex A2. 8.3.4 Again it should be remembered that petroleum products are assumed to be homogeneous at the point of sampling and require no additional stream conditioning unless specifically sampling for water content, or where the sampler is downstream of a blending manifold.
TABLE 1
2.13
10-60 L (3-15 gal) 20-60 L (5-15 gal) 4-20 L (1-5 gill) 1-20 L (1 qt-5 gal) 20-75 L (5-20 gal)
649
Recommended region for sampling point
FIG. 3
Recommended Sampling Area
direction of flow to verify that the probe is installed correctly. 10.1.3 The probe must be located in a zone where sufficient mixing results in adequate stream conditioning. This zone is generally from 3 to 10 diameters downstream of piping elements, .5 to 4 diameters from static mixers, and 3 to 10 diameters from power mixers. When static or power mixers are used, the manufacturer of the device should be consulted for the probe's optimum location. 10.1.4 The line from the outlet of the extractor to the sample receiver must continuously slope downward from the extractor to the receiver and contain no dead space. 10.1.5 The preferred installation of a combined probeextractor is in the horizontal plane. 10.1.6 If a vertical piping loop is used for stream conditioning, locate the probe in the downflow section of the loop to obtain the benefit of the additional stream conditioning provided by the three 90* elbows. Locate the probe a minimum of three pipe diameters downstream of the top 90* elbow and not closer than one-half pipe diameter upstream of the final exiting elbow (see Fig. 4). 10.1.7 According to tests sponsored by the American Petroleum Institute (API), locating a sample probe downstream of a single 90* bend is not recommended because of inadequate stream conditioning. 10.2 Probe Design." 10.2.1 The mechanical design of the probe should be compatible with the operating conditions of the pipeline and the fluid being sampled. There are three basic designs shown in Fig. 5. Probe openings should be in the center third of the
t!~ D 4177
[ V
MINIMUM
L [/PROBELOCA~ON r-V FIG. 4
General Vertical Piping Loop Configuration
cross sectional area of the pipe. 10.2.2 Probe designs commonly used are described as follows; 10.2.2.1 A closed end probe equipped with an open orifice (see Fig. 5A). 10.2.2.2 A short-radius elbow or pipe bend facing upstream. The end of the probe should be chamfered on the inside diameter to give a sharp entrance (see Fig. 5B). 10.2.2.3 A tube cut at a 45" angle with the angle facing upstream (see Fig. 5C).
11. Automatic Sampling Components l l.l Extractor--An automatic sample extractor is a device that extracts a sample (grab) from the flowing medium. The extractor may or may not be an integral part of the probe. The sample extractor should extract a consistent volume that is repeatable within _+5 % over the range of operating conditions and sampling rates. i 1.2 Controller--A sample controller is a device which governs the operation of the sample extractor. The sample controller should permit the selection of the sampling frequency.
12. Sampler Pacing 12.1 Custody Transfer MetersmCustody transfer meters should be used to pace the sampler where available. When flow is measured by multiple meters, the sampler should be paced by the combined total flow signal. Alternatively, a separate sampler may be installed in each meter run. The sample from each meter run must be considered a part of the total sample and in the same proportion as that meter's volume is to the total volume. 12.2 Special Flow Meters--When custody transfer is by tank measurements, a flow signal must be provided to the sample controller. This signal may be provided by an add-on flow metering device. These devices should have an accuracy of _ 10 % or better, over the total volume of the parcel. 12.3 Time Proportional Sampling--An automatic sampler should preferably operate in proportion to flow. However, sampling in a time proportional mode is acceptable if the flow rate variation is less than _ 10 % of the average rate over the entire parcel.
13. Primary Sample Receivers 13.1 A sample receiver/container is required to hold and maintain the composition of the sample in liquid form. This includes both stationary and portable receivers, either of which may be of variable or fixed volume design. If the loss of vapors will significantly affect the analysis of the sample, a variable volume type receiver should be considered. Mate-
rials of construction should be compatible with the petroleum or petroleum product sampled. 13.2 Stationary Receivers: 13.2.1 General Design FeaturesnThese features may not be applicable to some types of receivers, that is, variable volume receivers. 13.2. l.l Receiver design must allow for preparation of a homogeneous mixture of the sample. 13.2.1.2 The bottom of the receiver must be continuously sloped downward toward the drain to facilitate complete liquid withdrawal. There should be no internal pockets or dead spots. 13.2.1.3 Internal surfaces of the receiver should be designed to minimize corrosion, encrustation, and clingage. 13.2.1.4 A means should be provided to monitor filling of the receiver. If a sight glass is used, it must be easy to clean and not be a water trap. 13.2.1.5 A relief valve should be provided and set at a pressure that does not exceed the design pressure of the receiver. 13.2.1.6 A means to break vacuum should be provided to permit sample withdrawal from the receiver. 13.2.1.7 A pressure gage should be provided. 13.2.1.8 Receivers should be sheltered from adverse ambient conditions when in use. 13.2.1.9 Receivers may need to be heat traced or insulated, or both, when high pour point or high viscosity petroleum or petroleum products are sampled. Alternatively, they may be housed in heated and insulated housing. Exercise caution to ensure added heating does not affect the sample. 13.2.1.10 Use of multiple sample receivers should be considered to allow flexibility in sampling sequential parcels and line displacements. Exercise care in the piping design to prevent contamination between samples of different parcels. See Fig. 6. 13.2.1.11 Receivers should have an inspection cover or closure of sufficient size to facilitate easy inspection and cleaning. 13.2.1.12 Facilities for security sealing should be provided. 13.2.1.13 The system must be capable of completely draining the receiver, mixing pump, and associated piping. 13.2.1.14 The circulating system shall not contain any dead legs. 13.3 Portable Receivers--In addition to considerations outlined in 13.2, portable receivers may include the following additional features: 13.3.1 Light weight, 13.3.2 Quick release connections for easy connection/ disconnect to the probe/extractor and the laboratory mixer (see Fig. 7), and 13.3.3 Carrying handles. 13.4 Receiver SizemThe receiver should be sized to match its intended use and operating conditions. The size of the receiver is determined by the total volume of sample required, the number of grabs required, the volume of each grab and, transportability of the receiver if portable. Typical sample receiver sizes are shown in Table 1.
14. Sample Mixing and Handling 14.1 Sample in the receiver must be properly mixed to
650
~
D 4177
End of probe closed orifice facing upstream ~ T , ~ , o sMtannc~f:r~ltrers u diameter
or tubing 1/4"-2" ~ pipe
~oT~o
45" Bevel receiver r extractor
receiver r extractor
FIG. 5
~/
~
1/4"-2" ¢ pipe or tubing
~=~Toreceiver r extractor
Probe Designs
Probe or extractor
\
•
-
3-way ball valve-hand or motor Note 1 operated from control room ~
Minimize
manifold size and length
Quick ~ ' ~ ~ d i ~ n e c t
Solenoid E1 valves
(~
Probe or extractor
~"
Note
Installation Showing Portable Receivers
Sin.gle receiver
Multiple receivers
NOTEn6,4 or 9.5 mm (1/4 or a/a In.) tubing, as short as possible and sloping continuously toward the sample receiver, should be used. 9.5 mm (~e in.) tubing should be used where long sampling lines cannot be avoided or in crude oil service. Heat trace and insulate these lines when necessary. FIG. 6 Receiver(s) Installation
ensure a homogenous sample. Transfer of samples from the receiver to another container or the analytical glassware in which they will be analyzed requires special care to maintain their representative nature. See Practice D 5854 for detailed procedures.
NOTE 1--6.4 or 9.5 mm (=/s in.) tubing, as short as possible and sloping continuously toward the sample receiver should be used. Thr~¢~ghths inch tubing should be considered where long sampling lines cannot be avoided or the crude oil is viscous. Heat trace and Insulate these lines when necessary. NOTE 2--Sample should flow into a cennectidn at the top of the container. In warm climates, a sun shield should be provided to avoid excessive temperature changes in sample receivers. NOTE 3~ln warm climates, a sun shield should be provided to avoid excessive temperature changes In sample revivers. NOTE 4--In cold climates, consider placing sample receivers in a heated housing or heat trace and Insulate the receivers and sample lines. FIG, 7 Portable Receiver(s) Installation
controller must be able to record total number of grabs and total volume. 15.2.3 Piping arrangement at the ship's manifold will often distort the flow profile. The flow sensor, when operated under the piping and flow conditions at the ship's manifold, must meet the accuracy criteria in 12.2. 15.2.4 Stream conditioning is accomplished by velocity of the fluid and the piping elements ahead of the probe. The number of hoses, arms, and lines in service at any one time may need to be limited to maintain sufficiently high velocity. 15.2.5 The controller may be placed on the ship's deck, which is usually classified as a hazardous zoned area. If the controller is electronic, it should meet the requirements of the hazardous area. 15.2.6 Air supply must meet the requirements of the equipment. 15.2.7 For high pour or viscous fluids, particularly in cold climates, the line from the extractor to the receiver may require a thermally insulated high pressure hose or tubing. The receiver should be placed as close to the extractor as
15. Portable Samplers 15.1 A typical application of a portable sampling system is on board a marine vessel. There are also occasional applications on shore. The same criteria for representative sampling applies to both portable and stationary sampling systems. Exercise caution when using portable samplers on marine vessels due to the difficulty in verifying stream conditioning during actual operations. An example of a marine application is shown in Fig. 8. 15.2 Design Features--Special features and installation requirements for a portable sampler are: 15.2.1 A spool assembly fitted with a sample probe/ extractor and flow sensor is inserted between the ship's manifold and each loading/unloading arm or hose. If the grab size of each sampler is equal, a common receiver can be used. 15.2.2 A controller is required for each extractor. The 651
(~ D 4177
- -
Smnpl* Pmb*
Contrgl Unit
FIG. 8
Typical Portable Marine Installation
possible to minimize the hose length. The hose or tubing should have an internal diameter of 9.5 mm (% in.) or more and slope continuously downward from the extractor to the receiver. The line from the extractor to the receiver may have to be heat traced. 15.2.8 Filling of receivers should be monitored to ensure that each sampler is operating properly. Frequent visual inspection, level indicators, and weighing have proven to be acceptable monitoring methods. 15.2.9 The portable sampler is used intermittently; therefore the sample probe, extractor, and flow sensor should be cleaned after every use to prevent plugging. 15.2. I0 All components and installation must meet applicable regulations, that is, U.S. Coast Guard regulations. 15.3 Operating Considerations--The portable sampler operator must maintain operating conditions which provide adequate mixing and produce a representative sample. Performance criteria is given in Annex A5. To meet the criteria requires cooperation of the vessel crew and shore personnel. Special operating requirements are: 15.3.1 The portable sampler operator should keep the flow rate at each flow sensing device within its design range by limiting the number of loading lines or hoses in service during periods of low flow rates, for example, start-up, topping off, stripping, etc. 15.3.2 For discharge operations, the vessel compartment discharge sequence must be controlled so that the amount of free water being discharged during the start-up operation is less than 10 % of the total amount of water in the cargo. 15.3.3 For loadings, a shore tank with no free water is preferred for the initial pumping. Water drawing the tank or pumping a small portion of the tank to another shore tank prior to the opening tank gage, or both, are suggested.
16. Acceptance Tests 16.1 Testing is recommended to confirm that a sampling system is performing accurately. Annex A3 outlines methods for testing samplers that are used for the collection of S&W 652
or free water samples. The test methods fall in two general categories; Total System Testing and Component Testing. 16.2 Total System Testing--This test method is a volume balance test where tests are conducted for known amounts of water. It is designed to test the total system including the laboratory handling and mixing of sample. Two procedures are outlined. One involves only the sampler under test, the other utilizes an additional sampler to measure the baseline water. 16.3 Component Testing--This test method involves testing individually the components that comprise a sampling system. Where applicable, some of the component tests may be conducted prior to installation of the total system. Components to be tested include: 16.3. l Probe/extractor, 16.3.2 Profile (for stream conditioning), 16.3.3 Special flow meter, and 16.3.4 Primary sample receiver and mixer. 16.3.5 If a system design has been proven by testing, subsequent systems of the same design (for example, LACT Units), including piping configuration and operated under the same or less criterial conditions (that is, higher flow rate, higher viscosity, lower water content, etc.) need not be tested. Once a system or system design has been proven, the following checks can be used to confirm system reliability: Component
Check
Stream conditioning
Flow rate or pressure drop if equipped with power or static mixer. Profde test for systems with only piping elements. Compare recorded batch volume to known. Compare actual sample volume to expected volume. Compare actual sample volume to expected volume. Compare actual grab size to expected grab size.
Pacing device Extractor
16.3.6 Portable sampling systems can be tested by the component testing method except for proper stream conditioning. To compensate for this, the performance test for each operation has been designed to evaluate the operation of the sampler. This is shown in Annex A5. 16.4 Requirements for Acceptability--Testing by either the component or total system method requires that two out of three consecutive sets of test data repeat within the limits shown in Annex A3.
17. Operational Performance Checks/Reports 17.1 Monitoring of sampler performance is a necessary part of every sampling operation. Monitoring is required to make sure that the sample extractor is extracting a uniform grab in a flow proportional manner. This is normally accomplished by assessing the sample volume collected to ensure that it meets expectations for the equipment and transfer volume involved. 17.2 Several procedures may be used to accomplish this requirement, that is, sight glasses, gages, or weigh cells. Selection of a procedure should be based on (1) volume of transfer, (2) type of installation, (3) time interval of transfer, (4) whether the sampling facility is manned, (5) receiver type, (6) purpose of the sample, and (7) equipment used. 17.3 For LACT and ACT units, monitoring may consist of comparison between sample volume collected and expected sample volume. For very large transfers including marine transferee, more information may be desired as outlined in Annexes A4 and A5.
(~
I
8/~ELINE
SAMPLE
D 4177
I [
WATERINJECTION I AND
[
,Es, SAM,~E
i
i
I
I
~.
I
I.
I
I
I
SPREADING
I
BASELINESAMPLE I
I
Time NOTEmTimes are calculated based on minimum oil flow rate and the distance between the injection and the sample point. FIG. 9
Sequence of Acceptance Teat Activities
18. Keywords
isokinetic sampling; mixing elements; portable samplers; primary sample receiver; probe; representative sampling; representative sampling criteria; sampling handling; sample loop; sample mixing; stream conditioning
18.1 acceptance tests; automatic petroleum sampling; controllers; extractor; intermediate sampling receiver;
ANNEX (Mandatory Information)
AI. PRECAUTIONARY INFORMATION
A 1.1 Physical Characteristics and Fire Considerations: A 1.1.1 Personnel involved in the handling of petroleumrelated substances (and other chemical materials) should be familiar with their physical and chemical characteristics, including potential for fire, explosion, and reactivity, and appropriate emergency procedures. These procedures should comply with the individual company's safe operating practices and local, state, and federal regulations, including those covering the use of proper protective clothing and equipment. Personnel should be alert to avoid potential sources of ignition and should keep the materials' containers closed when not in use. Al.I.2 API Publication 2217 and Publication 20265 and any applicable regulations should be consulted when sampiing requires entry to confined spaces. A1.1.3 INFORMATION REGARDING PARTICULAR MATERIALS AND CONDITIONS SHOULD BE OBTAINED FROM THE EMPLOYER, THE MANUFACTURER OR SUPPLIER OF THAT MATERIAL OR THE MATERIAL SAFETY DATA SHEET. A1.2 Safety and Health Consideration: A 1.2.1 General." AI.2. I. 1 Potential health effects can result from exposure to any chemical and are dependent on the toxicity of the chemical, concentration, and length of the exposure. Everyone should minimize his or her exposure to work place
653
chemicals. The following general precautions are suggested: (a) Minimize skin and eye contact and breathing of vapors. (b) Keep chemicals away from the mouth; they can be harmful or fatal if swallowed or aspirated. (c) Keep containers closed when not in use. (d) Keep work areas as clean as possible and well ventilated. (e) Clean spills promptly and in accordance with pertinent safety, health, and environmental regulations. (]) Observe established exposure limits and use proper protective clothing and equipment. NOTE Al.l--Information on exposure limits can be found by consulting the most recent editions of the Occupational Safety and Health Standards, 29 Code of Federal RegulationsSections 11910.1000 and followingand the ACGIH publication "Threshold Limit Values for Chemical Substancesand PhysicalAgents in the Work Environment."~' AI.2.1.2 INFORMATION CONCERNING SAFETY AND HEALTH RISKS AND PROPER PRECAUTIONS WITH RESPECT TO PARTICULAR MATERIALS AND CONDITIONS SHOULD BE OBTAINED FROM THE EMPLOYER, THE MANUFACTURER OR THE MATERIAL SAFETY DATA SHEET. , t AvailablefromAmericanConferenceof GovernmentIndustrialHygienists, (ACGIH),Bldg. D-7, 6500 OlenwayAve., Cincinnati, OH 45211-4438.
1]~) D 4177 A2. T H E O R E T I C A L CALCULATIONS FOR SELECTING T H E S A M P L E R PROBE LOCATION A2.1 Introduction: A2.1.1 This annex describes calculation procedures for estimating the dispersion of water-in-oil at a sampling location. These procedures have a very simple theoretical base with many of the equations not being strictly applicable; therefore, they should be used with extreme caution in any practical application. A conservative approach is strongly recommended when estimating the acceptable limits for adequate dispersion (steam conditioning).
defined in Eq 2. Table A2.2 presents the relationship of C1/C2 with G. c = ~
NOTE A2.l--From IP Petroleum Measurement Manual, Part IV Sampling: A2.1.2 The equations contained in this annex have been shown to be valid for a large number of field data. The range of the field data covered the following correlating parameters: Relative density Pipe diameter Viscosity Flowing velocity Water concentration
(3)
where: AP = the pressure drop across the piping element, V --the flow rate at the pipe section in which energy is dissipated, and
NOT~ A 2 . 2 - - U s e caution when extrapolating outside o f these ranges.
A2.1.3 When evaluating if dispersion is adequate or not in a given system, using the worst case conditions is recommended. A2.1.4 When calculating the dispersion rate E in A2.3, it should be noted that dispersion energies of different piping elements are not additive in regard to dispersion, that is, when a series of elements is present, the element that should be considered is the one that dissipates energy the most. A2.1.5 As an aid in determining the element most likely to provide adequate dispersion, Fig. A2.2 has been developed. When using Fig. A2.2, it is important to consider it as a guide only and that particular attention should be paid to the notes. Fig. A2.2 does not preclude the need for a more detailed analysis of these elements, within a given system, shown by the table to be the most effective. A2.2 Symbols--The symbols used in Annex A2 are presented in Table A2.1. A2.3 Dispersion Factors: A2.3.1 As a measure of dispersion, the ratio of water concentration at the top of a horizontal pipe C~ to that at the bottom C2 is used. A CJC2 ratio of 0.9 to 1.0 indicates very good dispersion while a ratio of 0.4 or smaller indicates poor dispersion with a high potential for water stratification. Calculations giving ratios less than 0.7 should not be considered reliable as coalescence of water droplets invalidates the prediction technique. A2.3.2 The degree of dispersion in horizontal pipes can be estimated by: exp ( - ~ )
A2.3.4 It is important to note that the uncertainty of the calculations is such that errors in G of more than 20 % may result at low values of G. For this reason, it is recommended that no reliance be placed upon calculated G values of less than 3 and that additional energy dissipation calculated G value. A2.4 Determination of Energy Dissipation." A2.4.1 Two different techniques are given for determining the rate of energy dissipation. A2.4.2 Method A uses the relationship in Eq 3.
APV E = ~pp
.8927-.8550 (27"-34" API) 40 era-130 em (16 in.-52 in.) 6-25 c.St at 40"C >0-3.7 m/s (>0-12 if/s) 100 Dilute sample to most Convenient level.
S V I K
= = = =
slope of standard curve, mg N/count, volume of sample, I~L, detector response, intergration counts, and dilution factor (when applicable).
12. Precision and Bias 4
12.1 The precision of this test method as determined by statistical examination of interlaboratory results is as follows: 12.1.1 Repeatability--The difference between two test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following values in only one case in twenty, where X = the average of the two test results. r 0.15(X) °'54
Sample Size, IsL up to 40 up to 8 up to 8
=
11. Calculation
12.1.2 Reproducibility--The difference between two single and independent results obtained by different operators working in different laboratories on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following values in only one case in twenty, where X = the average of the two test results. R = 0.85(X) °'~4
I 1.1 For analyzers equipped with a calibration adjust, calculate the nitrogen content of the sample parts per million (mg/kg) by mass as follows: Nitrogen, mg/kg = ( I - B) x K/(V x D) (l) Nitrogen, mg/kg = ( I - B) x K/M (2) where: D = density of sample, g/mL, K = dilution factor, V = volume of sample, ~tL, M = mass of sample, mg, I = visual display reading of sample, ng N, and B = average of visual display readings of blank, ng N. 11.2 For analyzers not equipped with calibration adjust, calculate the milligrams per kilograms by mass nitrogen as follows: Nitrogen, mg/kg = I x S x K/(V x D) (3)
12.2 The bias of this test method has not been determined. Subcommittee D.02.03.0C intends to determine bias for this test method when proper standards are available. 13. Keywords 13.1 catalyst poison; chemiluminescence; nitrogen content; oxidative combustion; petroleum hydrocarbons
where: D = density of sample, g/mL,
( Supporting data are available from ASTM Headquarters. Request RR:D021199.
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and ff not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohockan, PA 19428.
715
(~l~ Designation:D4735-96 Standard Test Method for Determination of Trace Thiophene in Refined Benzene by Gas Chromatography 1 Th~s standard is issued under the fixed designation D 4735; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (d indicates an editorial change since the last revision or reapproval.
OSHA Regulations, 29 CFR, paragraphs 1910.1000 and 1910.12005
1. Scope 1.1 This test method covers the determination of thiophene in refined benzene in the range from 0.5 mg/kg to 5.0 mg/kg. The range of the test method may be extended by modifying the sample injection volume, calibration range, or sample dilution with thiophene-free solvent. 1.2 This test method has been found applicable to benzene characteristic of the type described in Specifications D 2359 and D 4734 and may be applicable to other types or grades of benzene only after the user has demonstrated that the procedure can completely resolve thiophene from the other organic contaminants contained in the sample. 1.3 The following applies to all specified limits in this test method: for purposes of determining conformance with this test method, an observed value or a calculated value shall be rounded off "to the nearest unit" in the last right-hand digit used in expressing the specification limit in accordance with the rounding-off method of Practice E 29. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 7.
3. Summary of Test Method 3.1 The thiophene concentration in refined benzene is determined at the milligram thiophene per kilogram sample level using conventional gas-liquid chromatography with a flame photometric detector. A reproducible volume of sample is injected. Quantitative results are obtained by the external standard technique using the measured peak area of thiophene. 4. Significance and Use 4.1 This test method is suitable for setting specifications on benzene and for use as an internal quality control tool where benzene is either produced or used in a manufacturing process. 4.2 This test method was found applicable for determining thiophene in refined benzene conforming to the specifications described in Specification D 2359 and may be applicable toward other grades of benzene if the user has taken the necessary precautions as described in the text. 4.3 This test method was developed as an alternative technique to Test Method D 1685. 5. Apparatus 5.1 Gas Chromatograph--Any chromatograph having a flame photometric detector may be used which can operate at the typical conditions described in Table 1. The user is referred to Practice E 260 for additional information about gas chromatography principles and procedures. 5.2 ColumnmThe column must provide complete resolution of thiophene from benzene and any other hydrocarbon impurities because of potential quenching effects by hydrocarbons on the light emissions from the thiophene. The columns described in Table 1 have been judged satisfactory. 5.3 Detector--Any flame photometric detector (FPD) can be used, provided it has sufficient sensitivity to produce a minimum peak height twice that of the base noise for a 4-~tL injection volume of 0.5 mg/kg thiophene in benzene. The user is referred to Practice E 840 for assistance in optimizing the operation and performance of the FPD. 5.4 Integrator--Electronic integration is recommended. 5.5 Recorder, a-c, l-mV range strip chart recorder is recommended. 5.6 Microsyringe, 10-I.tLcapacity.
2. Referenced Documents 2.1 A S T M Standards: D 1193 Specification for Reagent Water2 D 1685 Test Method for Traces of Thiophene in Benzene by Spectrophotometry3 D 2359 Specification for Refined Benzene-5353 D 3437 Practice for Sampling and Handling Liquid Cyclic Products 3 D 4734 Specification for Refined Benzene 5453 E 29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications 4 E 260 Practice for Packed Column Gas Chromatography4 E 840 Practice for Using Flame Photometric Detectors in Gas Chromatography4 2.2 Other Document: t This test method is under the jurisdiction of ASTM Committee D-16 on Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of Subcommittee DI6.0E on Instrumental Analysis. Current edition approved Feb. 10, 1996. Published April 1996. Originally published as D 4735 - 87. Last previous edition D 4735 - 87 (1991) ~'. 2 Annual Book of ASTM Standards, Vol 11.01. 3 Annual Book of ASTM Standards, Vol 06.04. 4 Annual Book of ASTM Standards, Vol 14.02.
5 Available from Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402.
716
~ TABLE 1 Column Tubing Phase Concentration, weight % Support Mesh Detector H=, mL/min Air I, mL/min Air II, mL/min Gas chromatographic conditions Inlet, *C Detector, °C Carrier Gas Flow Rate, mL/min Column Temperature, *C
D 4735
Thiophene in Benzene Instrumental Conditions A
B
C
6 ft x 1/8 in. Ni Steel TCEPE a 7 Chromosorb P-AW a 100/120
15 ft by 1/8 in. stainless steel SP-1000 10 Supelcoport 60/80
10 ft by 1/8 in. stainless steel OV-351 10 Chromosorb P-AW 80/100
140 80 170
140 80 170
140 80 170
150 220 helium 30 70
170 220 helium 30 90
180 250 helium 30 70
A Tetracyanoethylated pentaerythritol or pentrile. a Chromosorb P Is a registered trademark of the Manville Corp.
5.7 Volumetric Flasks, 50, 100 and 500-mL capacity. 5.8 Separatory Funnel, 1-L capacity.
6. Reagents and Materials
(CdCI2). Finally, wash with another lO0-mL portion of water and filter the benzene through medium filter paper into a storage bottle, stopper the bottle tightly and save for future use.
6.9 Sulfuric AcidmConcentrated H2SOa. 6.10 Thiophenes.
6. t Purity of Reagents--Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available. 6 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 6.2 Purity of Water--Unless otherwise indicated, reference to water shall be understood to mean reagent water conforming to Type IV of Specification D 1193. 6.3 Carrier Gas, nitrogen or helium, chromatographic grade. 6.4 Hydrogen, zero grade. 6.5 Compressed Air, hydrocarbon-free. 6.6 Cadmium Chloride Solution (20 g/L)--Dissolve 20 g of anhydrous cadmium chloride CdCI2 into 200 mL of water and dilute to 1 L. 6.7 Isatin Solution7--Add 0.5 g of isatin to 200 mL of chloroform. Heat under a fume hood to a temperature just below the boiling point of chloroform (61"C) and maintain for 5 min with stirring. Filter the hot solution through hardened rapid-filter paper into a 250-mL volumetric flask and dilute to volume. 6.8 Benzene, Thiophene-Free~Wash 700 mL of benzene in a 1000-mL separatory funnel to which has been added 5 mL of isatin solution, with successive 100-mL portions of concentrated sulfuric acid until the H 2 S O 4 layer is light yellow or colorless. Wash the benzene with 100 mL of water, then twice with 100 mL of cadmium chloride solution
7. Hazards 7.1 Benzene is considered a hazardous material. Consult current OSHA regulations and supplier's Material Safety Data Sheets, and local regulations for all materials used in this method. 8. Sampling and Handling 8.1 Sampling of benzene should follow safe rules in order to adhere to all safety precautions as outlined in the latest OSHA regulations. Refer to Practice D 3437 for proper sampling and handling of benzene. 9. Preparation of the Apparatus 9.1 The chromatographic separation of trace level sulfur compounds can be complicated by absorption of the sulfur compounds by the gas chromatographic system, Therefore, care should be taken to properly free the system of active sites where absorption or reactions could take place. 9.2 Follow the manufacturer's instructions for mounting the column into the gas chromatograph and adjusting the instrument to conditions described in Table 1. Allow the instrument and detector sufficient time to reach equilibrium. 10. Calibration Curve 10.1 Prepare a 500-mL stock solution of thiophene in benzene at the 100 mg/kg level by adding 0.04 g (38.0 gL) of thiopbene to 435 g (500 mL) of thiophene-free benzene. 10.2 Calculate the thiophene content of the stock solution according to the following equation: Thiophene, mg/kg = (.4 × 103)/B where:
6 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and Natwnal Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD. 7 Isatin 2,3-indolinedione such as Aldrich Catalog No. 11,461-8, available from Aldrich Chemical Co., Inc., 940 W. Saint Paul Ave., Milwaukee, WI 53233, or equivalent has been found satisfactory for this purpose.
s Thiophene such as Aldrich Catalog No. T3,180-1, available from Aldrich Chemical Co., Inc., 940 W. Saint Paul Ave., Milwaukee, Wi 53233, or equivalent has been found satisfactory for this purpose.
717
~ ) D 4735 1.79
IHZOP~EIE $0.33
.... O0
I . . . . . . . . I.I )lo
I ' ' ' ' 1 ' ' ' ' 1 ' ' ' ' 1 ' ' ' ' 1 ' ' 1 ' 1 , ' ' ' 1 ' ' ' ' 4S LO 7,S 90 IO.g ILO $$S
t§.OI
N|NUT[S
FIG. 1
Chromatogram Illus~ating the Analysis of 1.10 mg/kg Thiophene in Benzene
A B
-- weight of thiopcnc, mg, and = weight of benzene, g. I0.3 Prepare five calibration blends ranging from 0.00 to 10.0 mg/kg of thiophene in benzene by diluting the appropriate volume of stock solution into a known volume of thiophcnc-frcc benzene. I0.4 For example, an 87.0 mg/kg stock solution was prepared by dissolving 0.0378 g thiophcnc into 435 g of benzene. Aliquots of 0.00, 0.75, 1.0,2.0, and 5.0 m L of stock solution wcrc dissolved in 100 m L ofthiophcnc-frcc benzene to produce 0.00, 0.65, 0.87, 1.75, and 4.35 mg/kg, respectively. 10.5 Inject 4.0 ~L of each solution into the chromatograph. Integrate the area under the thiophene peak. Each standard solution and the blank should be analyzed in triplicate. NOTE l--Injection volumesmust be consistentand reproducible. 10.6 Prepare a calibration curve by plotting the intcgratod peak area versus milligram per kilogram of thiophen¢ on a sheet of log/log graph paper. NOTE 2 - - I n the sulfur mode, the FPD will exhibit a response that is
a nonlinear power law function. Please refer to Practice E 840 for additional informationon the characteristicsand usageof the FPD. 11. Procedure 11.1 Charge 4.0 ~tL of sample into the chromatograph. 11.2 Measure the area of the thiophene peak. The measurement of the sample peak should be consistent with the method for measuring peak areas in the calibration blends. A typical chromatogram is shown in Fig. 1 representing 1.10 mg/kg thiophene in benzene.
the calibration curve prepared in 10.6. 13. Report 13.1 Report the thiophene concentration to the nearest 0.01 mg/kg. 14. Precision and Bias 14.1 Precision: 14. I. 1 The following criteria should bc used to judge the acceptability of the 95 % probability level of the results obtained by this test method. The criteria were derived from a round robin between five laboratories. The data were obtained over 2 days using different operators. 14.1.2 Intermediate Precision (formerly called Repeatability)mResults in the same laboratory should not be considered suspect unless they differ by more than the amount shown in Table 2. 14.1.3 ReproducibilitynThe results submitted by two TABLE 2 Thiophene Concentration,
Intermediate Precision and Reproducibility Repeatability,
Reproducibility,
mg/kg
mg/kg
rng/kg
0.8O
0.040 0.078
0.060
1.80
0.078
laboratories should not be considered suspect unless they differ by more than the amount shown in Table 2. 14.2 Bias--The bias in this test method is being determined.
15. Keywords 15.1 benzene; flame photometric detector; gas chromatography; thiophene
12. Calculation 12.1 Determine the amount of thiophene directly from
718
tJ~ D 4735 The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned/n this standard. Users of this standard are expressly advised that detarm/nation of the validity of any such patent rights, and the risk of infringement of such rights, are entire/}/their own responsibility. This standard Is subject to revision at any time by the responsible technical committee and must be reviewed every five years and ff not revised, either reepproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohockan, PA 19428.
719
Designation: D 4737 - 96a
IP@ :,',",.:':,::,','::~,
An American National Standard
Designation: 3 8 0 / 9 4
Standard Test Method for Calculated Cetane Index by Four Variable Equation 1 This standard is issued under the fixed designation D 4737; the number immediately following the designation indicates the year of original adoption or, in the ease of revision, the year of last revision. A number in parentheses indicates the year of last reapprnval. A superscript epsilon (0 indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 The calculated Cetane Index by Four Variable Equation provides a means for estimating the ASTM eetane number of distillate fuels from density and recovery temperature measurements. The value computed from the equation is termed the Calculated Cetane Index by Four Variable Equation. 2 1.2 The Calculated Cetane Index by Four Variable Equation is not an optional method for expressing ASTM octane number. It is a supplementary tool for estimating cetane number when used with due regard for its limitations. 1.3 The test method "Calculated Cetane Index by Four Variable Equation" is particularly applicable to Grade I-D and Grade 2-D diesel fuel oils containing straight-run and cracked stocks, and blends of the two. It can also be used for heavier fuels with 90 % recovery points less than 382"C and for fuels containing non-petroleum derivatives from tar sands and oil shale. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
the ASTM cetane number and the density and 10 %, 50 %, and 90 % recovery temperatures of the fuel. The relationship is given by the following equation: CCI = 45.2 + (0.0892)(Tlojv) + [0.131 + (0.901) (B)][TsoN] + [0.0523 - (0.420)(B)] [TgoN] + [0.00049][(Tie,v)2 -- (Tgo~v)2] + (107)(B) + (60)(B)2 where: CCI = Calculated Cetane Index by Four Variable Equation, D = Density at 15"C, determined by Test Method D 1298, DN = D - 0 . 8 5 , B
= [e (-3"s×DN)] -
I,
T~o -
2. Referenced Documents
2.1 ASTM Standards: D 86 Test Method for Distillation of Petroleum Products 3 D 613 Test Method for Cetane Number of Diesel Fuel OiP D 1298 Test Method for Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method 3 D 4052 Test Method for Density and Relative Density of Liquids by Digital Density Meter5 3. Summary of Test Method 3.1 A correlation in SI units has been established between This test method is under the jurisdiction of ASTM Committee 1)-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee DOZE on Burner, Diesel, and Gas Turbine Fuel Oils. Current edition approved Nov. 10, 1996. Published January 1997. Originally published as D 4737 - 87. Last previous edition D 4737 - 96. 2 This method of estimating eetane number was developed by Chevron Research Co. See Ingham, M. C., et al. "Improved Predictive Equations for Cetane Number," SAE Paper No 860250. 3 Annual Book of A S T M Standards, Vol 05.01. 4 Annual Book of A S T M Standards, Vol 05.04. s Annual Book of A S T M Standards, Vol 05.02.
10% recovery temperature, *C, determined by Test Method D 86 and corrected to standard barometric pressure, TioN -- Tio - 215, Tso -- 50 % recovery temperature, *C, determined by Test Method 86 and corrected to standard barometric pressure, Tso~, = Tso - 260, T9o = 90 % recovery temperature, *C, determined by Test Method D 86 and corrected to standard barometric pressure, Tgo N = Tgo - 310. 3.2 The empirical equation for the Calculated Cetane Index by Four Variable Equation was derived using a generalized least squares fitting technique which accounted for measurement errors in the independent variables (fuel properties) as well as in the dependent variable (cetane number by Test Method D 613). The data base consisted of 1229 fuels including; commercial diesel fuels, refinery blending components and non-petroleum fuels derived from tar sands, shale, and coal. The analysis also accounted for bias amongst the individual sets of data comprising the data base.
4. Significance and Use 4.1 The Calculated Cetane Index by Four Variable Equation is useful for estimating ASTM cetane number when a test engine is not available for determining this property directly. It may be conveniently employed for estimating cetane number when the quantity of sample available is too small for an engine rating. In cases where the ASTM cetane number 720
~
D 4737
recommended range of application.
Part 1 - E s t i m a t e B a s e d on D e n s i t y a n d D 86 5 0 % R e c o v e r y T e m p e r a t u r e
5. Procedure
:: ,++:::
85 -D=0.685kg/L
.
-
~
75 :Part ! EsUmate:34. O,
:: .........
85
....
0.805
: _~.
, , ~
5.1 Determine the density of the fuel at 15°C to the nearest 0.0001 kg/L, as described in Test Method D 1298 or Test Method D 4052. 5.2 Determine the l0 %, 50 %, and 90 % recovery temperatures of the fuel to the nearest l°C, as described in Test Method D 86.
.:.
....
-:,-
+'_.
+ i.+ 1
~a:'++l
:- i+,-:! ~f..,~j: :h-o;8:O~l...q ,.. , +:;.~. ] :~0.8251,!.; '.:::1 ;:1 ++.,_ ;-'-~:: +Z z ~ . > ~ . ~ o ."rt- 0~ I,_, ~: 0.835/~'~ i ~t +"
+ .
~/r~L/+,,
..~'
~'
'
' '
6. C a l c u l a t i o n or Interpretation o f R e s u l t s
I-'-
6.1 Compute the Calculated Cctane Index by Four Variable Equation using the equation given in 3. I. The calculation is more easily performed using a computer or programmablc hand calculator. Round the value obtained to the nearest one-tenth. 6. I. 1 Calculated Cetanc Index by Four Variable Equation can also be easily determined by means of the homographs appearing in Figs. 1 through 3. Figure l is used to estimate the cetanc number of a fuel based on its density at 15°C and its 50 % recovery temperature. Fig. 2 is used to determine a correction for the estimate from Fig. 1 to account for deviations in the density and the 90 % recovery temperature of the fuel from average values. Figure 3 is used to determine a second correction for the estimate from Fig. 1 to account for deviations in the l0 % and the 90 % recovery temperatures of the fuel from average values. The corrections determined from Figs. 2 and 3 arc summed algebraically with the cctanc number estimate from Fig. l to find the Calculated Cetanc Index by Four Variable Equation. The
:-"
e-
."~-.I
%
~
~
0.845 -
~,
'.4.
::i
:'
(J "O '
'
I'~
"
• i + ' [,
35
-:"~;.~0.860
'
'. ~
-If, 5~ _~.:
~
+
~
~ . + +-.:...;,-+-,"
~
'
~:
~
........
I
: ' ':+
~+lll-+tl;
. ¢,,
225
250
._o.985 -
. :,+-i ~- I : :~,~
+~+ : , 1',t
..
- :,
-~..
;-.-~
4,t: ~
:-'2-.~ ~ I 0.890 ::,~,-T~:~
:z:;
2~ 200
0.876
.-r'-: 0.880 . :.- :-r-~-;l
275
~ll
:'-,
i~-I-1-i
~i,t 14:~~,4!,!
300
325
ASTM D 86 50% Recovery Temperature, °C FIG. 1
Calculated
Index
Cetane
Part 2 - C o r r e c t i o n f o r D e v i a t i o n s in Dessity a n d D 86 9 0 % R e c o v e r y T e m p e r a t u r e f r o m A v e r a g e Values 5
o : 0.6as kg/C
4
\ 3. 2
. . .
T90 = 323°C --~
----
~..
Part
2 Corr.
\;
:
+0.6
,,
j
,
: j.' /i
:
I t J +/" "-.,
",,t
0.90
t
-"
[
I
,
l
8 Example:
-
+ oi
.. .
Part 3 - C o r r e c t i o n for D e v i a t i o n s in D 86 1 0 % a n d 90% Recovery Temperatures from Average Values
i
2~,.4-i
I
1
i
.-" -
• Tg0 = 323oc
u.o4-~.'
260
-
t.)
.
~=
~ 4 ~'--"'~-- .:Z:
"ZZ +.~'
E
0 -I "
-2 -3
Z..... !
~
-4 ;.
.
-S 250
275
..... .'
1__.:]o_8_=
I _L__.~+l ..... !_% .
.
J,
t' 300
325
I + . 1-
I
_i I
'+
375
-2
"1 t-/i~ ., /. . . . 7 ,"~ _I)
ASTM O 86 90% Recovery Temperature,'oc
FIG. 2
-
+
._~
+", ,. o8oI-+ .t
350
--r~_+ =20
Calculated Cetane Index
4/
of a fuel has been previously established,the Calculated Cetane Index by Four Variable Equation is useful as a cctane number check on subsequent samples of that fuel, provided the fuel's source and mode of manufacture remain unchanged. 4.2 Within the range from 32.5 to 56.5 cctane number, the expected error of prediction of the Calculated Cetanc Index by Four Variable Equation will bc less than __.2cetane numbers for 65 % of the distillatefuels evaluated. Errors may be greater for fuels whose properties fall outside the
721
-S
_
,l
.
.
-6__/~
/.~. .
~
.
j.
.
.
--I-+-
.....
~
5:+.)
.
+
.
.
~
--:--': .. .
.
.
.
,
I.
.
.
--
t
1
-
+
350
Calculated Cetane Index
+
,
375
ASTM D 86 90% Recovery Temperature, °C FIG. 3
i
i''+
" ! :! - 325
;:
.
. . . . . .
-
'Zi!:-:.-_.[;_::t-_+-:+_ i. t-:i 300
--
.
---Il ":-" -'--
. . . . .
275
.
++: + :;I ]t-+:
i-
. . . . . . . . . . .
I
i +I
"~..~
'------
q~
i:
:-
~ O4737 method of using these nomographs is indicated by the illustrative example shown below and on Figs. 1 through 3.
7.
Measured Fuel Properties Test Method D 613 Cetane Number Test Method D 1298 Density at 15"C, kg/L Test Method D 86 10 % Recovery Temperature, *C Test Method D 86 50 % Recovery Temperature, °C Test Method D 86 90 % Recovery Temperature, "C
37.0 0.885 234 274 323
Calculated Cetane Index Estimate from Fig. 1 Correction from Fig. 2 Correction from Fig. 3
34.0 +0.6 +2.5 CCI s 37.1
6.2 The Calculated Cetane Index by Four Variable Equation possesses certain inherent limitations which must be recognized in its application. These are as follows: 6.2.1 It is not applicable to fuels containing additives for raising the cetane number. 6.2.2 It is not applicable to pure hydrocarbons, nor to non-petroleum fuels derived from coal. 6.2.3 Substantial inaccuracies in correlation may occur if the equation is applied to residual fuels or crude oils.
Precision and Bias
7.1 The determination of Calculated Cetane Index by Four Variable Equation from measured density at 15"C and measured 10 %, 50 % and 90 % recovery temperatures is exact. 7.2 Precision--The precision of the Calculated Cetane Index by Four Variable Equation is dependent on the precision of the original density and recovery temperature determinations which enter into the calculation. Test Method D 1298 has a stated repeatability limit of 0.0006 kg/L and a stated reproducibility limit of 0.0015 kg/L at 15°C. Test Method D 86 has stated repeatability and reprodueibility limits which vary with the rate of change of recovery temperature. See Figs. 2 through 7 and Tables 7 through 10 of Test Method D 86 for details. 7.3 Bias--No general statement is made on bias of this test method since a comparison with accepted reference values is not available. 8. Keywords 8.1 cetane; cetane index; diesel fuel
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of Infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 100 Bert Harbor Drive, West Conshohocken, PA 19428.
722
~[~
Designation: D 4808 - 92
An Arnencan NatK3nat Standard
Standard Test Methods for Hydrogen Content of Light Distillates, Middle Distillates, Gas Oils, and Residua by Low-Resolution Nuclear Magnetic Resonance Spectroscopy 1 This standard is issued under the fixed designation D 4808; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 These test methods cover the determination of the hydrogen content of petroleum products ranging from atmospheric distillates to vacuum residua using a continuous wave, low-resolution nuclear magnetic resonance spectrometer. (Test Method D 3701 is the preferred method for determining the hydrogen content of aviation turbine fuels using nuclear magnetic resonance spectroscopy.) 1.2 Three test methods are included here that account for the special characteristics of different petroleum products and apply to the following distillation ranges: Test Method
Petroleum Products
Boiling Range, "C ('F) (approximate)
A B
Light Distillates Middle Distillates, Gas Oils Residua
15-260 (60-500) 200-370 (400-700) 370-510 (700-950) 510+ (950+)
C
1.3 The preferred units are mass percent. 1.4 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 6.1.
records in a non-destructive fashion the absolute concentration of hydrogen atoms in the reference standard and test sample. The absolute hydrogen concentrations reported by the integrator on the NMR instrument for the standard and test specimens are used as a means of comparing the theoretical hydrogen content of the standard with that of the sample, the result being expressed as the hydrogen content (on a mass percent basis) of the sample. 3.2 In order to assure an accurate measure of the absolute hydrogen content of the reference standard and sample, it is necessary to ensure that the measured hydrogen integrator counts are always directly proportional to the absolute hydrogen content of the standard and sample. 3.3 Undercounting of the reference standard with respect to the sample is avoided in Test Methods B and C by dilution of the standard with a relaxation reagent solution. Undercounting of highly viscous or solid test samples is avoided by dissolving the sample in a non-hydrogen containing solvent, which assures that all of the weighed sample is in a fluid and homogeneous solution at the time of measurement. An elevated sample temperature at the time of measurement also ensures a homogeneous liquid-phase sample.
4. Significance and Use
2. Referenced Documents
4.1 The hydrogen content represents a fundamental quality of a petroleum product that has been correlated with many of the performance characteristics of that product. 4.2 This test method provides a simple and more precise alternative to existing test methods, specifically combustion techniques, (Test Method D 5291), for determining the hydrogen content on a range of petroleum products.
2.1 ASTM Standards: D3701 Test Method for Hydrogen Content of Aviation Turbine Fuels by Low Resolution Nuclear Magnetic Resonance Spectrometry2 D4057 Practice for Manual Sampling of Petroleum and Petroleum Products2 D 5291 Test Method for Instrumental Determination of Carbon, Hydrogen, and Nitrogen in Petroleum Products and Lubricants3
5. Apparatus NOTEl--This test method has been written around the Newport Analyzer Mark IIIF or it's replacement version, the Newport 4000 (Oxford AnalyticalInstruments,Ltd., Oxford, England)and the details ofthe test methodare to be read in conjunctionwith the manufacturer's handbook. These instruments have demonstrated statisticallyindistinguishable performance in these standard methods and in Test Method D 3701. Any similarinstrumentis acceptable providedthat the new instrument is adequatelycorrelatedand proved to be statisticallysimilar.
3. Summary of Test Methods 3.1 A test specimen is compared in a continuous wave, low-resolution nuclear magnetic resonance (NMR) spectrometer with a reference standard sample. The spectrometer
5.1 Nuclear Magnetic Resonance Spectrometer: 5.1.1 A low.resolution, continuous wave instrument capable of measuring a nuclear magnetic resonance signal due to hydrogen atoms in the sample and includes an excitation and detection coil of suitable dimensions to contain the test cell; an electronic unit, to control and monitor the magnet
t This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee I:)02.03 on Elemental Analysis. Current edition approved Aug. 15, 1992. Published October 1992. Originally published as D 4808 - 88. Last previous edition D 4808 - 88. 2 Annual Book of ASTM Standards, Vol 05.02. 3 Annual Book of ASTM Standards, Vol 05.03.
723
(~ 8 HOLES lOS DEEP FOR NESSLER TUBES
D 4808 6. Reagents and Materials 4
:~ HOLES I05 DEEP
6.1 Purity of Reagents--Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available. 4 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 6.2 ReJbrence Standard--n-Dodecane.
203
~
PLASTIC 'KNOD
k.Jk.Jk.Jk.J
NOTE 2: Warning--Flammable. 4l
METAL INSERTION RO~,~ APPROX S 0
6.3 Relaxation Reagent Solution prepared from ferric acetylacetonate (Fe(acac)3 - MW = 353.16, reagent grade)-Prepare a fresh 0.02 M Fe(acac)3 solution by dissolving 1.77 g of Fe(acac)3 in 250 mL TCE. If any of the ferric acetylacetonate remains undissolved, filter the solution and use the filtrate in subsequent steps. 6.4 "l'etrachh,'oethylene (7'CE).
!
3S 0
I- _t.S~.
t ii ii i I iI ~
:
I t I __.j
N(n[~ 3: Warning--Cancer-suspect agent.
[ 1 ~ RREAD
1
CONDITIONING BLOCK MATERIAL ALUMINIUM ALLOY
"F
7. Sampling
7.1 Take a homogeneous sample in accordance with Practice D 4057. Mix the sample prior to taking a representative aliquot as the test specimen. Middle distillates, gas oils and residue can require heating to facilitate mixing to obtain a homogeneous test specimen as described in 9.2.2.2 and 9.3.2.
_.,J
Pt.UG MATERIAL PTFE
FIG. 1 ConditioningBlock and InsertionRod 8. Preparation of Apparatus
and coil, and containing: circuits, to control and adjust the radio-frequency level and audio-frequency gain; and integrating counter, with variable time period in seconds. 5.1.2 Test Methods B and C also require that the instrument has the ability to equilibrate samples within the probe at an elevated temperature (50°C). 5.2 Conditioning Block--A block of aluminum alloy drilled with holes of sufficient size to accommodate the test cells with the mean height of the sample being at least 20 mm below the top of the conditioning block, capable of holding the sample at the given test temperature (see Fig. 1). 5.3 Test Cells--Nessler-type tubes of approximately 100mL capacity with an external diameter of 33.7 4- 0.5 mm and an internal diameter of 31.0 4- 0.5 mm marked at a distance of 51 mm above the bottom of the tube by a ring around the circumference. 5.4 Pol.vtetrafluoroethylene (PTFE) Plugs for closing the test cells and made from pure PTFE. 5.5 Insertion Rod--A metal rod with a threaded end used for inserting and removing the PTFE plugs from the test cells (see Fig. 1). 5.6 Analytical Balance--A top pan-type balance, capable of weighing the test cells in an upright position to an accuracy of at least 0.001 g. 5.7 Beakers, 150 mL and 50 mL with pour spouts. 5.8 Glass Stirring Rod, approximately 250-mm length.
8.1 Read and follow the manufacturer's instructions for preparing the instrument to take measurements. Take special care to prevent the instrument and conditioning block from experiencing rapid temperature fluctuations; for example, avoid direct sunlight and drafts resulting from air conditioning or fans. 8.2 Adequate temperature equilibration of the instrument probe assembly after adjustment to an elevated temperature is essential. Due to the size of test specimen and probe assembly specified by these methods, adequate thermal equilibration may require several hours. 8.3 The results obtained during the use of the instrument are susceptible to error arising from changes in the local magnetic environment. Exercise care to ensure that there is a minimum of metallic material in the immediate vicinity of the instrument and keep this constant throughout the course of a series of determinations. 8.4 Set the instrument controls to the following conditions: 4"Reagent Chemicals, American Chemical Society Specifications," Am. Chemical Soc., Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see "Reagent Chemicals and Standards," by Joseph Rosin, D. Van Nostrand Co., Inc., New York, NY, and the "United States Pharmacopeia."
724
D 4808 Parameter Gate width (G) Audio-Frequency Gain (Arb. units) Radio-frequency Excitation (taA) Integration Time (seconds) Probe Temperature ('C)
Test Method A
Test Method B
Test Method C
1.5 500
1.5 400-600
1.5 400-600
20 128 Room Temp
20 128 50
20 128 50
NOTE 2--Burets can also be used to aid the addition of TCE and relaxation reagent solutions. 9.2.1.4 Transfer this solution from the beaker to the test cell using the glass rod to prevent splashing the liquid above the line inscribed on the test cell. Fill the test cell to the prescribed level, just below this mark. 9.2.1.5 Continue as in 9.1.2 through 9.1.3. 9.2.1.6 Weigh the test cell containing the reference solution and plug. Record the weight of the reference solution to the nearest 0.001 g as W~. 9.2.1.7 Weigh the beaker and glass rod containing the unused solution and record the weight of the remaining solution to the nearest 0.001 g as W2. 9.2.1.8 Place the test cell containing reference solution into the conditioning block to equilibrate. 9.2.2 Test Specimen Preparation: 9.2.2. l Take a clean and dry test cell with PTFE plug and a 150-mL beaker with glass stirring rod. Weigh the test cell with plug and the beaker with glass rod to the nearest mg and record as tare weights. 9.2.2.2 Add 20 g of the test specimen to the beaker. Record this weight to the nearest 0.001 g as S,... All samples must be homogeneous prior to sampling. If the sample is viscous or contains waxy materials, heat the sample in its container to approximately 60"C and mix with a high-speed shear mixer prior to sampling. 9.2.2.3 To the beaker containing sample, add 13.3 g of TCE (40 % dilution of the test sample with TCE). Mix the solution thoroughly using the glass rod. NOTE 4--For some samples, it is necessaryto heat and stir until the sample is completely homogeneous. Maintain the liquid level with additional TCE during heating if necessary. 9.2.2.4 Continue as in 9.2.1.4 through 9.2.1.8. 9.3 Test Method CmResidue 9.3.1 Take a clean and dry test cell with PTFE plug, a 150-mL beaker, and a glass rod. Weigh each of them to the nearest 0.001 g and record as tare weights. 9.3.2 Add 15 g of reference standard or test specimen to the beaker. Record this weight to the nearest 0.001 g as Sw. All samples must be homogeneous prior to sampling. If the sample is viscous or contains waxy materials, heat the sample in its container to approximately 60"C and mix with a high-speed shear mixer prior to sampling. 9.3.3 To the beaker, add 17.2 g of TCE and 5.3 g of relaxation reagent solution (60 % dilution with 1 mg of relaxation reagent per 1 mL). Mix thoroughly using the glass stirring rod. (See Note 4.) 9.3.4 Continue as described in 9.2.1.4 through 9.2.1.8.
8.5 Place a test cell containing typical test specimen in the coil and assure that the tuning of the instrument results in two coincident resonance curves on the oscilloscope. Recheck this condition after changing samples. 8.6 Remove the test cell from the coil and observe that the signal readout from the instrument integrator is now 0 _ 3 units. Check this condition periodically to ensure that no contamination of the coil with hydrogen-containing material has occurred. 9. Preparation of Test Specimen and Standard 9.1 Test Method A--Light Distillates 9.1.1 Take a clean and dry test cell and PTFE plug and weigh them together to the nearest 0.001 g and record the weight. Add 30 _+ 1 mL of the reference standard or test specimen to the tube, taking extreme care to prevent splashing the liquid above the line inscribed on the tube. Use a pipet for this operation. 9.1.2 Using the insertion rod, push the PTFE plug into the tube until it is about 3 cm above the liquid surface, being careful to keep the tube upright. A gentle twisting or rocking of the plug as it is inserted usually aids the escape of air from the test cell and ensure that the lip of the PTFE plug is turned up around the entire circumference. Take care to assure that this is so, since a plug that is not properly inserted allows sample evaporation and gives rise to erroneous results. NOTE l--If difficultiesare encountered in the insertion of the PTFE plug, this operation is facilitatedby insertinga length of thin (less than 0.2-ram diameter) and clean copper wire down the inside surface of the test cell until it is approximately4 cm from the graduation mark and then pushingthe PTFE plug down past the wire which is then removed. 9.1.3 Unscrew the insertion rod carefully and remove without disturbing the plug and without contacting the liquid with the under surface of the plug. 9.1.4 Weigh the test cell containing the test specimen or standard and plug. Record this weight as Ws or WR, respectively, to the nearest 0.001 g. 9.1.5 Place the test cell in the sample conditioning block to equilibrate. 9.1.6 Use procedures 9.1.1 to 9.1.5 to prepare both the reference and sample test cells. 9.2 Test Method B--Middle Distillates, Gas Oils 9.2.1 Reference Standard Preparation: 9.2.1.1 Take a clean and dry test cell with PTFE plug and a 150-mL beaker with glass rod. Weigh the test cell with plug and beaker with glass rod to the nearest 0.001 g and record as tare weights. 9.2.1.2 Add 20 g of the reference standard, n-dodecane, to the beaker. Record this weight to the nearest 0.001 g as Sw. 9.2.1.3 To the beaker add 8.6 g TCE and 4.7 g of relaxation reagent solution as described in section 6.3 consisting of TCE and Fe(acac) 3 (40 % dilution of reference standard with I mg relaxation reagent/mL). Mix thoroughly using the glass stirring rod.
10. Procedures 10.1 Test Methods A, B, and C: 10.1.1 Leave the reference standard and the test specimens in the conditioning block for at least 0.5 h, to ensure that they reach the specified test temperature. The temperature of the conditioning block must be maintained at the same temperature required for the NMR measurement as specified in 8.4. 10.1.2 Take the reference standard and place it carefully into the instrument sample probe (coil), being careful that the liquid does not splash onto the under side of the PTFE plug. When fully inserted, the top of the test cell is just above 725
~) D 4808 Repeatability (r) end Reproducibility (R) Precision Intervals for Test Methods A, B, and C in Units of Mass Percent Hydrogen
of material during the transfer to the test cell. 1 !. i. 1 Test Method A - - N o t applicable. 11. !.2 Test Methods B and C:
TABLE 1
mess ~
Test Method A
Test Method B
Test Method C
H
r
R
r
R
r
R
9.00 9.25 9.50 9.75 10.00 10,25 10.50 10.75 11.00 11.25 11.50 11.75 12.00 12.25 12.50 12.75 13.00 13.25 13.50 13.75 14.00 14.25 14.50 14.75 15.00 15.25 15.50 15.75 16,00
0.13 0.13 0.13 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11
0.42 0.41 0.41 0.41 0.40 0.40 0.40 0.40 0.40 0.39 0.39 0.39 0.39 0.38 0.38 0.38 0.38 0.38 0.38 0.37 0.37 0.37 0.37 0,37 0.37 0.36 0,36 0.36 0.36
0.12 0.13 0.14 0.14 0.15 0.16 0.17 0.17 0.18 0.19 0.20 0.21 0.22 0.23 0.23 0.24 0.25 0.26 0.27 0.28 0.29 0.30 0.32 0.33 0.34 0.35 0.36 0.37 0.38
0.25 0.27 0.28 0.29 0.31 0.33 0.34 0.36 0.38 0.39 0.41 0.43 0.45 0.47 0.48 0.50 0.52 0.54 0.56 0.59 0.61 0.63 0.65 0.67 0.70 0.72 0.74 0.77 0.79
0.41 0.39 0.37 0.35 0.33 0.32 0.30 0.29 0.28 0.26 0.25 0.24 0.23 0.22 0.21 0.20 0.20 0.19 0.18 0.18 0.17 0.16 0.16 0.15 0.15 0.14 0.14 0.13 0.13
0.87 0.82 0.78 0.74 0.70 0.67 0.64 0.61 0.58 0.56 0.53 0.51 0.49 0.47 0.45 0.43 0.42 0.40 0.39 0.37 0.36 0.35 0.33 0.32 0.31 0.30 0.29 0.28 0,27
WR or Ws = Sw × ( Wi)/( W, + W,) where: WR or W s = weight of reference material or test specimen in the test cell, Sw = weight of standard or test specimen in the preparation beaker, W~ = weight of solution in the NMR test cell, W2 = weight of solution remaining in the preparation beaker. 11.2 Hydrogen Content: 11.2.1 Calculate mass percent hydrogen content as follows: Hydrogen Content (mass %) (S/R) × (WR/Ws) × (15.39) where: S = mean of integrator counts on test specimen under test, R --- mean of integrator counts on reference standard, WR -- mass of reference standard in the test cell, Ws ffi mass of test specimen in the test cell and, 15.39 = mass % hydrogen in the reference sample, ndodecane.
12. Report 12.1 Report the mass percent hydrogen content on the test sample to the nearest 0.01 mass % hydrogen.
the cover of the instrument unit. 10.1.3 Check that the peaks on the oscilloscope are coincident and, if this is not so, adjust the tuning as described by the manufacturer's instructions until they are. 10.1.4 After the reference standard is in the magnet unit for at least 3 s, push the reset button to begin a measurement. 10.1.5 After a count time of 128 s, the digital display stops at its final value. Record the integrator counts and reset the instrument to take a second measurement. Record a total of seven readings, averaging the last five. 10.1.6 Remove the test cell containing reference standard from the instrument and reweigh after it has cooled to room temperature. If this weight differs significantly from the weight obtained in 9.1.4 or 9.2.1.6, the PTFE plug need not have sealed properly and the result is considered suspect. This additional weighing step is required due to the presence of the TCE diluent in some samples. 10.1.7 Replace the reference standard in the conditioning block and make similar readings on the test specimen to be tested.
13. Precision and Bias s 13.1 The precision of this test method as obtained by statistical examination of interlaboratory test results is as follows: 13.1.1 Repeatability--The difference between successive test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method exceed the following value only in one case in twenty (see Table 1): Test Method A--Light Distillates Test Method B--Middle Distillates and Gas Oils Test Method C--Residua
0.22(X o 2s) 0.0015(X 2) 33.3(X-2)
where X is the sample mean. 13.1.2 Reproducibility--The difference between two single and independent results obtained by different operators working in different laboratories on identical test material would, in the long run, in the normal and correct operation of the test method exceed the following value in one case in twenty (see Table 1):
NOTE 5 - - M e a s u r e m e n t s are affected by temperature variations in the sample and reference standard so these test cells are always returned to the conditioning block if additional measurements are anticipated on the same sample.
Test Method A--Light Distillates Test Method B--Middle Distillates and Gas Oils Test Method C--Residua
0,72(X o 25) O.0031(X2) 70.3(X -2)
where X is the sample mean.
11. Calculation 11.1 Determination of the weight of test specimen or reference material delivered to the NMR test cell. This calculation accounts for the dilution with TCE and the loss
s Supporting data are available from ASTM Headquarters. Request RR:D021186.
726
1~) D 4808 13.2 Bias: 13.2. l A 1985 research report indicated that the hydrogen content determined by Test Methods A, B, and C are not biased with respect to data obtained by combustion techniques. 13.2.2 A 1977 research report indicated that the hydrogen content determined by Test Method A (same as D 3701) is
biased high with respect to the expected value for pure known hydrocarbons. 14. Keywords 14.1 distillate; gas oil; hydrogen content; light distillate; middle distillate; nuclear magnetic; petroleum products; residua; resonance spectroscopy
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted m connection with any item mentioned in this standard, Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsJbihty. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every hve years and if not revised, either reepproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received s fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
727
~{~l~) Designation:D 4810-88 (Reapproved 1994)~1 Standard Test Method for Hydrogen Sulfide in Natural Gas Using Length-of-Stain Detector Tubes 1 This standard is issued under the fixed designation D 4810; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last re.approval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval. el Section 8 was added editorially in January 1994.
1. Scope 1.1 This test method covers a procedure for a rapid and simple field determination of hydrogen sulfide in natural gas pipelines. Available detector tubes provide a total measuring range of0.5 ppm by volume up to 40 % by volume, although the majority of applications will be on the lower end of this range (that is, under 120 ppm). 1.2 Typically, sulfur dioxide and mercaptans may cause positive interferences. In some cases, nitrogen dioxide can cause a negative interference. Most detector tubes will have a "preclcanse" layer designed to remove certain interferences up to some maximum interferent level. Consult manufacturers' instructions for specific interference information. 1.3 The values stated in SI units are to be regarded as the standard. 1.4 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
system is direct reading, easily portable, and completely suited to making rapid spot checks for hydrogen sulfide under field conditions. 4, Significance and Use
4.1 The measurement of hydrogen sulfide in natural gas is important, due to the gas quality specifications, the corrosive nature of H2S on pipeline materials, and the effects of H2S on utilization equipment. 4.2 This test method provides inexpensive field screening of hydrogen sulfide. The system design is such that it may be used by nontechnical personnel, with a minimum of proper training. 5. Apparatus 5.1 Length-of-Stain Detector Tube and Calibration Scale--A sealed glass tube with breakoff tips sized to fit the tube holder of the pump. The reagent layer inside the tube, typically a silica gel s u b s ~ t e coated with the active chemicals, must be specific for hydrogen sulfide, and must produce a distinct color change when exposed to a sample of gas containing hydrogen sulfide. Any substances known to interfere must be listed in the instructions accompanying the tubes. A calibration scale should be marked directly on the tube, or other markings which provide for easy interpretation of hydrogen sulfide content from a separate calibration scale supplied with the tubes. The calibration scale shall correlate hydrogen sulfide concentration to the length of the color stain. Shelf life of the detector tubes must be a minimum of two years from date of manufacture, when stored according to manufacturers' recommendations. 5.2 Detector Tube Pump---A hand-operated pump of a piston or bellows type. It must be capable of drawing 100 cm 3 per stroke of sample through the detector tube with a volume tolerance of:t:5 cm3. 3 It must be specifically designed for use with detector tubes.
2. Referenced Document 2.1 Gas Processors Association Standard: No. 2377-86 Test for Hydrogen Sulfide in Natural Gas Using Length of Stain Tubes 2 3. Summary of Test Method
3.1 The sample is drawn through a detector tube fdled with a specially prepared chemical. Any hydrogen sulfide present in the sampling reacts with the chemical to produce a color change, or stain. The length of the stain produced in the detector tube, when exposed to a measured volume of sample, is directly proportional to the amount of hydrogen sulfide present in the sample. A hand-operated piston or bellows-type pump is used to draw a measured volume of sample through the tube at a controlled rate of flow. The length of stain produced is converted to ppm (by volume) hydrogen sulfide (H2S), by comparison to a calibration scale supplied by the manufacturer for each box of detection tubes (higher range tubes have units of percent by volume). The
NOT~ I~A detector tube and pump together form a unit and must be used as such. Each manufacturer calibrates detector tubes to match the flowcharacteristicsof their specificpump. Crossingbrands of pumps and tubes is not permitted, as considerable loss of system accuracy is likelyto occur? (It should be noted that at leastone manufacturerallows extended samples up to 100 pumpstrokes to obtain lower detection levels. This may be automated for screening purposes by drawing the sample from an inert collapsable container by vacuum displacement.
i This test method is under the jurisdiction of ASTM Committee I).3 on Gaseous Fuels and is the direct responsibility of Subcommittee D03.05 on Determination of Special Constituents of Gaseous Fuels. Current edition approved April 29, 1988. Published June 1988. 2 Available from Gas Processors Association, 1812 First National Bank Bldg., Tulsa, OK 74103.
s Direct Reading Colorimetric Indicator Tubes Manual, 1st Ed., American Industrial Hygiene Association, 1976, Akron, OH 4431 !,
728
~)
D 4810
The sample flow rate should be maintained within ±5 % of the manufacturer's specified flow rate. Accuracy losses are apt to occur in such special applications, and such a system is recommended only for screening purposes. Consult manufacturers regarding limitations.)
CONTNOL VALVE\ SOURCEVALVE~
5.3 Gas Sampling Chamber--Any container that provides for access of the detector tube into a uniform flow of sample gas at atmospheric pressure, and isolates the sample from the surrounding atmosphere. A stainless steel needle valve (or pressure regulator) is placed between the source valve and the sampling chamber for the purpose of throttling the sample flow. Flow rate should approximate one to two volume changes per minute, or, at minimum, provide positive exit gas flow throughout the detector tube sampling period.
~
PLASTICONO T N E R ~ SUITABLEFLEXIBLE TUBING
NOTE 2--A suitable sampling chamber may be devised from a polyethylenewash bottle of nominal 500-mL(16-oz)or l-L (32-oz) size. The wash bottle's internal delivery tube provides for delivery of the sample gas to the bottom of the bottle. A 12.5-ram (I/2-in.) hole cut in the bottle's cap provides access for the detector tube and vent for the purge gas (Fig. l). (An alternate flow-throughsampler may be fashioned using a l-gal Ziploc-type food storage bag. The flexibleline enters one corner of the bag's open end and extends to the bottom of the bag. The opposite corner of the open end is used for tube access and sample vent. The remainder of the bag's top is sealed shut. The basic procedure for the sampler in Fig. l applies.) NOTE 3--An alternate sampling container is a collectionbag made of a material suitable for the collection of natural gas (for example, Mylar). The sampling bag should have a minimum capacity of 2 L. 6. Procedure 6.1 Select a sampling point that will provide access to a representative sample of the gas to be tested (for example, source valve on the main line). The sample point should be on top of the pipeline, and equipped with a stainless steel sample probe extending into the middle third of the pipeline. Open the source valve momentarily to clear the valve and connecting nipple of foreign materials. 6.2 Install needle valve (or pressure regulator) at the source valve outlet. Connect sampling chamber using the shortest length of flexible tubing possible (Fig. 1). Avoid using tubing that reacts with or absorbs H2S, such as copper or natural rubber. Use materials such as TFE-fluorocarbon, vinyl, polyethylene, or stainless steel. 6.3 Open source valve. Open needle valve enough to obtain positive flow of gas through chamber, in accordance with 5.3. Purge the container for at least 3 min. (Fig. l). NoTe 4--If a collection bag is used instead of a sampling chamber, follow 6.1 and 6.2, substituting the bag for the chamber. Follow 6.3, disconnecting the bag when filled. Deflate the bag to provide a purge, and fill a second time to provide a sample. The bag must be flattened completelyprior to each filling (Note 3). 6.4 Before each series of measurements, test the pump for leaks by operating it with an unbroken tube in place. Consult the manufacturer's instructions for leak check procedure details and for maintenance instruction, if leaks are detected. The leak check typically takes one minute. 6.5 Select a detector tube with the range that best encompasses the expected H2S concentration. Reading accuracy is improved when the stain length extends into the upper half of the calibration scale. Consult manufacturer's guidelines
729
~]~
~-- PUMP
~
TUBEACCEEE • GAE VENT Ii
GAS 8AMPLING
~!
CHAMBER
~.._._
~
[ ~
DETECTOR TUBE
FIG. 1 ApparatusSchematic for using multiple strokes to achieve a lower range on a given tube. 6.6 Break off the tube tips and insert the tube into the pump, observing the flow direction indication on the tube. Place the detector tube into the sampling chamber through the access hole, so that the tube inlet is near the chamber center (Fig. l). NOTe 5--Detector tubes have temperature limits of 0 to 40"C (32 to 104°F), and sample gases must remain in that range throughout the test. Cooling probes are available for sample temperatures exceeding40"C. 6.7 Operate the pump to draw the measured sample volume through the detector tube. Observe tube instructions when applying multiple strokes. Assure that a positive flow is maintained throughout the sample duration at the sampling chamber gas exit vent. Observe tube instructions for proper sampling time per pump stroke. The tube inlet must remain in position inside the sampling chamber until the sample is completed. Many detector tube pumps will have stroke finish indicators that eliminate the need to time the sample. NOTe 6--Ira collectionbag is used, the sample is drawn from the bag via a flexible tubing connection. Do not squeeze the bag during sampling. Allow the bag to collapse under pump vacuum, so that the pump's flow characteristics are not altered. 6.8 Remove the tube from the pump and immediately read the H2S concentration from the tube's calibration scale, or from the charts provided in the box of tubes. Read the tube at the maximum point of the stain. If "channeling" has occurred (non-uniform stain length), read the maximum and minimum stain lengths and average the two readings. NOTe 7--If the calibration scale is not printed directly on the detector tube, be sure that any separate calibration chart is the proper match for the tube in use.
O o 4a10
NOTE 8--Although the amount of chemicals contained in detector tubes is very small, the tubes should not be disposed of carelessly. A general disposal method includes soaking the opened tubes in water prior to tube disposal. The water should be pH neutralized prior to its disposal.
toring. 4 NIOSH tested tubes at 1/2, 1, 2, and 5 times the Threshold Limit Value (TLV), requiring ±25 % accuracy at the three higher levels, and ±35 % at the V2TLV level.5 (For example, H2S with a TLV of l0 ppm was tested at levels of 5, 10, 20, and 50 ppm.) The higher tolerance allowed at the low level was due to the loss of accuracy for shorter stain lengths.3 NIOSH discontinued this program in 1983, and it was picked up by the Safety Equipment Institute (SEI) in 1986. 7.1.1 The Gas Processors Association standard No. 2377 for natural gas testing via H2S detector tubes summarizes detector tube accuracy testing in natural gas in which all reported results are within ±23 %. 7.2 Repeatability--Duplicate results by the same operator under the same test conditions, should produce results within ±10 % between 3 and 120 ppm H2S and ±5 % between 0.05 and 5 % H2S (see GPA No. 2377), Repeatability is optimized when all tests using a single brand are conducted with detector tubes of the same lot number.
7. Precision and Bins
8. Keywords 8.1 gaseous fuels; natural gas
7.1 The accuracy of detector tube systems is generally considered to be ±25 %. This value is based on programs conducted by the National Institute of Occupational Safety and Health (NIOSH) in certifying detector tubes for low level contaminants in air, adapted to worker exposure moni-
4 Septon, J. C. and Wilczek, T., *'Evaluation of Hydrogen Sulfide Detector Tubes," App. Ind. Hys., Yol. I, No. 4, 11/86. S"NIOSH Certification Requirements for Gas Detector Tube Units," NIOSH/TC/A-012, 7/78.
6.9 If the number of strokes used differs from the number of strokes specified for the calibration scale, correct the reading, as below: specified strokes ppm (corrected) ffi ppm (reading) x actualstrokes 6.10 Record the reading immediately, along with the gas temperature and the barometric pressure. Observe any temperature corrections supplied in the tube instructions. Altitude corrections become significant at elevations above 2000 ft. Correct for barometric pressure, as below: 760 mm H~g ppm (corrected)ffi ppm (reading) × barometric pressure m mm Hg
The American Society for Testing end Materials takes no pesitlon respecting the validity of any patent rights auerted in connection with any item mentioned in this standard. Users of this Manderd are e ~ l y advised that determination of the vatlditF of any 8uoh patent rights, and the risk of Infringement of such rights, ere entirely their own respormlbitity. This standard is subject to revision st any time by the responsible technical committee and must be reviewed every five years and If not revised, either reapproved or withdrawn. Your conmlante are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1918 Race St., Philadelphia, PA 19103.
730
q~[~ Designation: D 4815 - 94a Standard Test Method for Determination of MTBE, ETBE, TAME, DIPE, tertiary-Amyl Alcohol and C 1 to C4 Alcohols in Gasoline by Gas Chromatography 1 This standard is issued under the fixed designation D 4815; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (4) indicates an editorial change since the last revision or reapproval. o NoTE--Paragraph 15.2 was corrected editorially and the designation date was changed effective July 25, 1994.
1. Scope 1.1 This test method is designed for the determination of ethers and alcohols in gasolines by gas chromatography. Specific compounds determined are: methyl tert-butylether (MTBE), ethyl tert-butylether (ETBE), tert-amylmethylether (TAME), diisopropylether (DIPE), methanol, ethanol, isopropanol, n-propanol, isobutanol, tert-butanol, secbutanol, n-butanol, and tert-pentanol (tert-amylalcohol). 1.2 Individual ethers are determined from 0.1 to 20.0 mass percent. Individual alcohols are determined from 0.1 to 12.0 mass pe'rcent. Equations used to convert to mass percent oxyger~ and to volume % of individual compounds are provided. 1.3 Alcohol-based fuels such as M-85 and E-85, MTBE product, ethanol product and denatured alcohol are specifically excluded from this method. The methanol content of M-85 fuel is considered beyond the operating range of the system. 1.4 Benzene, while detected, cannot be quantified using this test method and must be analyzed by alternate methodology (Test Method D 3606 or D 4420). 1.5 SI (metric) units are preferred and used throughout this standard. Alternate units, in common usage, are also provided to increase clarity and aid the users of this test method. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
D 3606 Test Method for Benzene and Toluene in Finished Motor and Aviation Gasoline by Gas Chromatography 3 D 4052 Test Method for Density and Relative Density of Liquids by Digital Density Meter 3 D4057 Practice for Manual Sampling of Petroleum and Petroleum Products 3 D 4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards 3 D 4420 Test Method for Aromatics in Finished Gasoline by Gas Chromatography 3 3. Terminology 3. I Descriptions of Terms Specific to This Standard: 3.1.1 low volume connector--a special union for connecting two lengths of tubing 1.6 mm inside diameter and smaller. Sometimes this is referred to as zero dead volume union. 3.1.2 MTBE--methyl tertiary-butylether. 3.1.3 ETBEmethyl tertiary-butylether. 3.1.4 TAME--tertiary-amyl methylether. 3.1.5 DIPEmdiisopropylether. 3.1.6 tertiary-amyl alcohol--tertiary-pentanol. 3.1.7 oxygenate--aqy oxygen-containing organic compound which can be used as a fuel or fuel supplement, for example, various alcohols and ethers. 3.1.8 split ratio---in capillary gas chromatography, the ratio of the total flow of carrier gas to the sample inlet versus the flow of the carrier gas to the capillary column, expressed by split ratio = (S + C)/C (I) where: S ffi flow rate at the splitter vent, and C = flow rate at the column outlet. 3.1.9 TCEP-- 1,2,3-tris-2-cyanoethoxypropane--a gas chromatographic liquid phase. 3.1.10 WCOT--a type of capillary gas chromatographic column prepared by coating the inside of the capillary with a thin film of stationary phase.
2. Referenced Documents 2.1 ASTM Standards: D 1298 Test Method for Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method 2 D 1744 Test Method for Water in Liquid Petroleum Products by Karl Fischer Reagent 2
4. Summary of Test Method 4.1 An appropriate internal standard such as 1,2dimethoxyethane (ethylene glycol dimethyl ether) is added to
This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee 1302.04 on Hydrocarbon Analysis. Current edition approved July 25, 1994. Published September 1994, Originally published as D 4815 - 89. Last previous edition D 4815 - 94. 2 Annual Book of ASTM Standards, Vol 05.01.
3 Annual Book of ASTM Standards, Vol 05.02.
731
(@) D 4815 the sample which is then introduced into a gas chromatograph equipped with two columns and a column switching valve. The sample first passes onto a polar TCEP column which elutes lighter hydrocarbons to vent and retains the oxygenated and heavier hydrocarbons. 4.2 After methylcyclopentane, but before DIPE and MTBE elute from the polar column, the valve is switched to backflush the oxygenates onto a WCOT non-polar column. The alcohols and ethers elute from the non-polar column in boiling point order, before elution of any major hydrocarbon constituents. 4.3 After benzene and TAME elute from the non-polar column, the column switching valve is switched back to its original position to backflush the heavy hydrocarbtms. 4.4 The eluted components are detected by a flame ionization or thermal conductivity detector. The detector response, proportional to the component concentration, is recorded; the peak areas are measured; and the concentration of each component is calculated with reference to the internal standard. 5. Significance and Use 5.1 Ethers, alcohols, and other oxygenates can be added to gasoline to increase octane number and to reduce emissions. Type and concentration of various oxygenates are specified and regulated to ensure acceptable commercial gasoline quality. Drivability, vapor pressure, phase separation, exhaust and evaporative emissions are some of the concerns associated with oxygenated fuels. 5.2 This test method is applicable to both quality control in the production of gasoline and for the determination of deliberate or extraneous oxygenate additions or contamination.
6. Apparatus 6.1 Chromatograph--While any gas chromatographic system, which is capable of adequately resolving the individual ethers and alcohols that are presented in Table l, can be used for these analyses, a gas chromatographic instrument TABLE 1 Pertinent Physical Constants and Retention CharactadsUcs for TCEP/WCOT Column Set Conditions as in Table 2
Component
Water Methano~ Ethanol Isolxopan~ tart-Butanol n-Propano~
MTBE sec-Butenol DIPE Isol~tenol ETBE tert-Pentanol 1,2-Dimethoxyethene
Relative Retention Retention Time Time, Min. (MTBE - (DME = 1.00) 1.00)
Relative Molecular Densatyat W e i g h t 15.56/ 15,56°C
2.90 3.15 3.48 3.63 4.15 4,56 5.04 5.36 5.76 6.00 8.20 6.43 6.80
0.58 0.63 0.69 0.76 0.82 0.90 1.00 1.06 1.14 1.19 1.23 1.28 1.35
0.43 0.46 0.51 0.56 0.61 0.67 0.74 0.79 0.85 0.88 0.91 0.95 1.00
18,0 32.0 46.1 60.1 74.1 60,1 88.2 74.1 102.2 74.1 102.2 88.1 90.1
1.000 0.7963 0.7939 0.7699 0.7922 0.8080 0.7460 0.8114 0.7300 0.8058 0.7452 0.6170 0,8720
7.04 7.41 8.17
1.40 1.47 1.62
1.04 1.09 1,20
74.1 78,1 102.2
0.8137 0.8830 0.7758
TABLE 2
Chromatographic Operation CondiUons
Temperatures Column Oven Injector, °C OetectorwTCD, °C wFID, °C Valve °C
(DME) rvButeno~ Benzene TAME
which can be operated at the conditions given in Table 2, and having a column switching and backflushing system equivalent to Fig. l has been found acceptable. Carrier gas flow controllers shall be capable of precise control where the required flow rates are low (Table 2). Pressure control devices and gages shall be capable of precise control for the typical pressures required. 6. 1.2 Detector--A thermal conductivity detector or flame ionization detector, can be used. The system shall have sufficient sensitivity and stability to obtain a recorder deflection of at least 2 mm at a signal-to-noise ratio of at least '5 to l for 0.005 volume % concentration of an oxygenate. 6.1.3 Switching and Backflushing ValvenA valve, to be located within the gas chromatographic column oven, capable of performing the functions described in Section 11 and illustrated in Fig. 1. The valve shall be of low volume design and not contribute significantly to chromatographic deterioration. 6.1.3.1 Valco Model No. A 4CIOWP, 1.6 mm (1/16 in.) fittings. This particular valve was used in the majority of the analyses used for the development of Section 15. 6.1.3.2 ValcoModelNo. CIOW, 0.8 mm ('/32 in.) fittings. This valve is recommended for use with columns of 0.32 mm inside diameter and smaller. 6.1.3.3 Some gas chromatographs are equipped with an auxiliary oven which can be used to contain the valve and polar column. In such a configuration, the nonpolar column is located in the main oven and the temperature can be adjusted for optimum oxygenates resolution. 6.1.4 An automatic valve switching device must be used to ensure repeatable switching times. Such a device should be synchronized with injection and data collection times. 6.1.5 Injection System--The chromatograph should be equipped with a splitting-type inlet device if capillary columns or flame ionization detection are used. Split injection is necessary to maintain the actual chromatographed sample size within the limits of column and detector optimum efficiency and linearity. 6.1.5.1 Some gas chromatographs are equipped with oncolumn injectors and autosamplers which can inject small samples sizes. Such injection systems can be used provided that sample size is within the limit of the column and detectors optimum efficiency and linearity. 6.1.5.2 Microlitre syringes, automatic syringe injectors, and liquid sampling valves have been used successfully for introducing representative samples into the gas chromatographic inlet. 6.2 Data Presentation or Calculation, or Both: 6.2.1 Recorder--A recording potentiometer or equivalent with a full-scale deflection of 5 mV or less can be used to
Flows, mL/min 60 200 200 250 60
to injector 75 Column 5 Auxiliary 3 Makeup 18
Carrier Gas: Helium Samplesize, lZLA Split ratio Backflush,rain Valve reset time Total Analysis time
1.0-3.0 15:1 0.2-0.3 8-10 rain 18-20 mln
A Sample size must be adjusted so that alcohols in the range of 0.1 to 12.0 mass "/~and ethers in the range of 0.I to 20.0 mass "/, are eluted from the column and measured ilnsedyat the detector. A semple size of 1.0 ~L has been introduced in most cases.
732
@ o 4a s
,yoo
ADJUSTABLE
•
~-
/.
I
"
POLAR (TCEP)
~
I /
IX,
ca. 100 mPa-s dynamic viscosity) has been reported in the literature. For additional information, consult the Journal of Physical Chemistry, Vol 84, 1980, pp. 158-162 and the Journal of the Chemical Society Faraday Translation, Vol 86 (I), 1990, pp. 145-149.
781
fl~ D 5002 The American Society for Testing end Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, end the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and ff not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
782
q~l~ Designation: D 5060 - 95
Standard Test Method for Determining Impurities in High-Purity Ethylbenzene by Gas Chromatography I This standard is issued under the fixed designation D 5060; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (0 indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 This test method describes the analysis of normally occurring impurities in, and the purity of, ethylbenzene by gas chromatography. Impurities determined include nonaromatic hydrocarbons, benzene, toluene, xylenes, cumene, and diethylbenzene isomers. 1.2 This test method is applicable for impurities at concentrations from 0.001 to 1.000 % and for ethylbenzene purities of 99 % or higher. At this level, p-xylene may not be detected. 1.3 The following applies to all specified limits in this standard: for purposes of determining conformance with this standard, an observed value or a calculated value shall be rounded off "to the nearest unit" in the last right-hand digit used in expressing the specification limit, in accordance with the rounding-off method of Practice E 29. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement, see Section 7.
3. Summary of Test Method 3.1 A known amount of internal standard is added to the sample. A gas chromatograph equipped with a flame ionization detector and a polar fused silica capillary column is used for the analysis. The impurities are measured relative to the internal standard. Ethylbenzene purity is calculated by subtracting the impurities found from I00.00 %. 4. Significance and Use 4.1 The test is suitable for setting specifications on ethylbenzene and for use as an internal quality control tool where ethylbenzene is used in manufacturing processes. It may be used in development or research work involving ethylbenzene. 4.2 Purity is commonly reported by subtracting the determined expected impurities from 100 %. Absolute purity cannot be determined if unknown impurities are present.
2.1 A S T M Standards: D 3437 Practice for Sampling and Handling Liquid Cyclic Products 2 D 4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards 3 E 29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications4 E 355 Practice for Gas Chromatography Terms and Relationships 4 E 1510 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs 4 2.2 Other Documents: OSHA Regulations, 29 CFR, paragraphs 1910.1000 and 1910.12005
5. Apparatus 5.1 Gas Chromatograph--Any gas chromatograph having a flame ionization detector and a splitter injector suitable for use with a fused-silica capillary column may be used, provided the system has sufficient sensitivity to obtain a minimum peak height response of 0.1 mV for 0.010 % internal standard when operated at the stated conditions. Background noise at these conditions is not to exceed 3 IxV. 5.2 Chromatographic Column, fused silica capillary, 60 m long, 0.32-mm inside diameter, internally coated to a 0.5-p-m thickness with a bonded (crosslinked) polyethylene glycol. Other columns may be used after it has been established that such column is capable of separating all major impurities and the internal standard from the ethylbenzene under operating conditions appropriate for the column. 5.3 Recorder, 1-mV, 1 s or less full scale response or electronic integration with tangent capabilities (recommended). 5.4 Microsyringe, 10-i.tL. 5.5 Microsyringe, 50-1xL. 5.6 Volumetric Flask, 50-mL.
1 This test method is under the jurisdiction of ASTM Committee D-16 on Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of Subcommittee DI6.OH on Styrene, Ethylbenzene, and C9 and Cto Aromatic Hydrocarbons. Current edition approved May 15, 1995. Published July 1995. Originally published as D 5090 - 90. Last previous edition D 5090 - 90. 2 Annual Book of ASTM Standards, Vol 06.04. 3 Annual Book of ASTM Standards, Vol 05.02. 4 Annual Book of ASTM Standards, Vol 14.02. s Avadable from Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402.
6. Reagents and Materials 6.1 Carrier Gas, hydrogen or helium, chromatographic grade. 6.2 Compressed Air, oil-free. 6.3 Hydrogen, chromatographic grade. 6.4 Nitrogen, chromatographic grade. 6.5 Pure Compounds for Calibration--n-Nonane, benzene, toluene, ethylbenzene, and o-xylene. The purity of the ethylbenzene should be 99.8 % or better. The ethylbenzene
2. Referenced Documents
783
(~ D 5060 TABLE 1
must be analyzed and corrections made in the composition of the calibration blend as required. The purity of all other compounds should be 99 % or greater. If the purity is less than 99 %, the concentration and identification of the impurities must be known so that the composition of the calibration standard can be adjusted for the presence of the impurities. 6.6 n-Undecane, for use as internal standard, 99 % or greater purity.
Typical Instrument Parameters
Carrier gas Carrier gas flow rate at 1100C, mL/m=n Detector Detector temperature, *C Injection port temperature, *C Hydrogen flow rate, mL/min Airflow rate, mL/min Make-up gas Make-up gas flow rate, mL/min Split flow, mL/min Column temperature, *C Chart speed, cm/min Sample size, pL
7. Hazards 7.1 Consult current OSHA regulations, supplier's Material Safety Data Sheets, and local regulations for all materials used in this test method.
helium 1.2 flame )onizat=on
240 230 30 275 nitrogen 23 150 110 1 0.6
and obtain the chromatogram. A typical chromatogram is shown in Fig. 1. 11. Calculation 11.1 Measure the areas of all peaks, including the internal standard, except for the ethylbenzene peak. 11.2 Sum all the peaks eluting before ethylbenzene except for benzene, toluene, and the internal standard. Identify this sum as nonaromatic hydrocarbons. 11.3 Calculate the weight percent of the individual impurities, Ci, to the nearest 0.001%, as follows:
8. Sampling 8.1 Guidelines for taking samples from bulk are given in Practice D 3437. 9. Calibration 9. I Prepare a calibration blend of each compound listed in 6.5 and n-undecane at the 0.2 weight % level in ethylbenzene as described in Practice D 4307. n-Nonane represents the nonaromatic hydrocarbons. A series of calibration blends that span the concentration range should be prepared, one at the expected level of impurities, another at one half the expected level, and a third series at twice the expected level. 9.2 Analyze the ethylbenzene used in preparing the calibration blend as described in 10.3. 9.3 Analyze the calibration blend as described in 10.3. 9.4 Calculate response factors as follows:
c,=
0.0512
A,R,
As where: Ai = area of impurity, R~ = response factor for impurity, and As = area of internal standard. 11.4 Use the response factor determined for o-xylene for all the peaks eluting after ethylbenzene, and the response factor determined for n-nonane for all the nonaromatic hydrocarbon peaks. 11.5 Calculate the purity of the ethylbenzene by subtracting the sum of the impurities from 100.00.
c, )
12. Report 12.1 Report the following information: 12.1.1 The concentration of each impurity to the nearest 0.001 weight %, and 12.1.2 The purity of ethylbenzene to the nearest 0.01 weight %.
where: R~ = response factor for impurity relative to internal standard, A~ = area of impurity peak in calibration blend, Ab --- area of impurity in ethylbenzene in calibration blend, Cs = concentration of internal standard, weight %, As,, -- area of internal standard peak in calibration blend, As, b = area of internal standard peak in stock ethylbenzene, and Ci = concentration of impurity, weight %. 9.5 Calculate response factor to the nearest 0.001.
13. Precision and Bias 13.1 The following criteria should be used to judge the acceptability of the 95 % probability level of the results obtained by this test method. The criteria were derived from a round robin between seven laboratories. The data were obtained over two days using different operators. 13.1.1 Intermediate PrecisioJt--Results in the same laboratory should not be considered suspect unless they differ by more than the amount shown in Table 2. 13.1.2 ReproducibilitymThe results submitted by two laboratories should not be considered suspect unless they differ by more than the amount shown in Table 2. 13.2 Bias--No statement is made about bias since no acceptable reference material and value are available.
10. Procedure 10.1 Install the chromatographic column and establish stable instrument operation at the operating conditions shown in Table 1. Refer to instructions provided by the manufacturer of the gas chromatograph and Practices E 355 and E 1510. 10.2 Fill a 50-mL volumetric flask to the mark with test specimen. With a microsyringe, add 30 IxL of the standard. Mix well. Using a density of 0.740 for n-undecane and 0.867 for ethylbenzene, this solution will contain 0.0512 weight % internal standard. 10.3 Inject 0.6 ~tL of solution into the gas chromatograph
14. Keywords 14.1 ethylbenzene; ethylbenzene purity; impurities in ethylbenzene 784
i{~'~ D 5 0 6 0 START
h.22
{-
~.s7
Non-aromatic Benzene
hydrocarbons .
.
.
.
.
S.12
.
Toluene
s.78
thyZbenzene
f
p-Xylene
.
.
.
.
,£
~ .7~ II :|~m_~y~ene 7.33
Cumene
9 -Xv~ene
E_
7.6z
7.ss
n-Propylbenzene Rrhv]to]uenes
ee30
sec-Butylbenzene 9.20
10.21 10.5~
Diethylbenzenes
P 11 .28
FIG. 1
TABLE 2 Component sec-Butylbenzene n-Propylbenzene m~o-Ethyltoluenes o-Xylene Cumene Benzene Toluene m,p-Xylene Diethylbenzenes Ethylbenzene
Typical Chromatogram (see Table 1) Intermediate Precision and Reproducibility Concentration, Intermediate Weight % Precision 0.002 0.010 0.014 0.013 0.012 0.024 0.592 0.090 0.008 99.05
0.001 0.002 0.003 0.004 0.003 0.004 0.083 0.024 0.001 0.200
Reproducibility 0.003 0.003 0.002 0.007 0.002 0.005 0.100 0.019 0.003 0.186
The American Society for Testing and Materials takes no position respecting the vafidity of any patent rights asserted m connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
785
(~l~
Designation: D 5134 - 92
Standard Test Method for Detailed Analysis of Petroleum Naphthas through n-Nonane by Capillary Gas Chromatography 1 This standard is issued under the fixed designation D 5134; the number immediately following the designation indicates the year of original adoption or, in the ease of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (¢) indicates an editorial change since the last revision or reapproval.
INTRODUCTION Despite the many advances in capillary gas chromatography instrumentation and the remarkable resolution achievable, it has proven difficult to standardize a test method for the analysis of a mixture as complex as petroleum naphtha. Because of the proliferation of numerous, similar columns and the endless choices of phase thickness, column internal diameter, length, etc., as well as instrument operating parameters, many laboratories use similar but nol identical methods for the capillary GC analysis of petroleum naphthas. Even minute differences in column polarity or column oven temperature, for example, can change resolution or elution order of components and make their identification an individual interpretive process rather than the desirable, objective application of standard retention data. To avoid this, stringent column specifications and temperature and flow conditions have been adopted in this test method to ensure consistent elution order and resolution and reproducible retention times. Strict adherence to the specified conditions is essential to the successful application of this test method. I. Scope I. 1 This test method covers the determination of hydrocarbon components of petroleum naphthas as enumerated in Table 1. Components eluting after n-nonane (bp 150.8"C) are determined as a single group. 1.2 This test method is applicable to olefin-free (0.015 C/g Minimum detectability ................ 5 × 10 - t 2 g carbon/second Linearity ....................................... >i07 6.2 Sample Introduction System--Manual or automatic liquid syringe sample injection to the splitting injector may be employed. Devices capable of 0.2 p.L to 1.0 ~tL injections are suitable. It should be noted that inadequate splitter design or poor injection technique, or both, can result in sample fractionation. Operating conditions which preclude fractionation should be determined in accordance with Section 11. 6.3 Electronic Data Acquisition System--Any data acquisition and integration device used for quantitation of these analyses must meet or exceed these minimum requirements: 6.3.1 Capacity for at least 250 peaks/analysis. 6.3.2 Normalized area percent calculation with response factors. 6.3.3 Identification of individual components by retention time. 6.3.4 Noise and spike rejection capability. 6.3.5 Sampling rates for fast (1000 at and above 1272 mg/kg. These data indicate that this test method makes correct predictions for samples containing 1272 mg/kg and probably correct predictions for samples between 870 and 1272 mg/kg Cl. 11.2 Precision and Bias Statement for Method B. 11.2.1 Precision--The following criteria should be used for judging the acceptability of results. 11.2.2 Repeatability--The difference between successive test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, and in the normal and correct operation of this test method, exceed the stated values only in one case in twenty. Repeatability = 46. l X °,25
color remains throughout the solution. 8.7.3 Examine the titrating syringe and determine where the tip of the plunger is in relation to the scale marked on the outside of the syringe barrel. Determine the amount of titrant (to the nearest 0.025 mL) that has been used.
9. Interpretation of Results 9.1 Calculations are not required when prepackaged kits are used. 9.2 For Method A, report results as either greater than or less than 1000 mg/kg (ppm). 9.3 For Method B, calculate the concentration (mg/kg) of total chlorine in the original oil sample by the following equation: Chlorine (mg/kg) = ( V - 0.05)(c)(35.45)(F) m
(1)
where: V = volume of mercuric nitrate titrant used, mL, 0.05 = volume of excess titrant required for color formation, mL, c = concentration of mercuric nitrate solution, meq/L, for example, 27.4, 35.45 = average atomic weight of chlorine, F = dilution factor due to adding 7 mL of buffer solution and extracting only 5 mL for analysis, for example, 1.4, and m = mass of oil sample used, for example, 0.34 g for a volume of 0.4 mL motor oil, g.
where: X = method result, mg/kg. I 1.2.3 Reproducibility--The difference between two single and independent results obtained by different operators working in different laboratories on identical test material would, in the long run, and in the normal and correct operation of this test method, exceed the stated x,alues only in one case in twenty.
10. Quality Control
Reproducibility = 84.44 X ° 25
10.1 Test each sample two times. For Method A, if the results do not agree, a third test must be performed. Report the results of the two that agree. For Method B, the two results should be within 20 % or 300 mg/kg (whichever is larger) of each other. If they are not, perform a third test and report the results of the two tests that agree.
where: X = method result, mg/kg. 11.2.4 In a collaborative study, 4 using prepackaged kits, ten laboratories analyzed seven used oil samples and one unused motor oil sample. 11.2.5 Bias--No bias statement is made for this test method because results obtained for total chlorine were determined only by the test method itself.
11. Precision and Bias
12. Keywords 12.1 chlorine; field test; halogen; on-site testing; test kit; used oil
11.1 For Method A, no formal statement is made about either the precision or bias of the test method because the result merely states whether there is conformance to the criteria for success specified in the procedure, that is, a blue or yellow color in the final solution. In a collaborative
4 Data supporting this study is available from ASTM Headquarters. Request RR:D02-1368,
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, end the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reeppreved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, if you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
879
q~l~ Designation: D 5386 - 93b Standard Test Method for Color of Liquids Using Tristimulus Colorimetry I This standard is issued under the fixed designation D 5386; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 This test method covers an instrumental method for the CIE (Commission International de l'Eclairage) tristimulus measurement of the color of near-clear liquid samples. The measurement is converted to color ratings in the platinum-cobalt system. 1.2 This test method has been found applicable to the color measurement of clear, liquid samples, free of haze, with nominal platinum cobalt color values in the 0 to 30 range. It is applicable to nonfiuorescent liquids with light absorption characteristics similar to those of the platinum cobalt color standard solutions. Test Methods D 1686, D2108, and E 450 deal with the visual and instrumental measurement of near-clear liquids. 1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. Referenced Documents
2.1 A S T M Standards: D 1193 Specification for Reagent Water2 D 1209 Test Method for Color of Clear Liquids (PlatinumCobalt Scale)3 D 1686 Test Method for Color of Solid Aromatic Hydrocarbons and Related Materials in the Molten State (Platinum-Cobalt Scale)3 D 1925 Test Method for Yellowness Index of Plastics 4 D2108 Test Method for Color of Halogenated Organic Solvents and Their Admixtures (Platinum-Cobalt Scale)5 D 3437 Practice for Sampling and Handling Liquid Cyclic Products5 E 179 Guide for Selection of Geometric Conditions for Measurement of Reflectance and Transmission Properties of Materials6 E 308 Test Method for Computing the Colors of Objects by Using the CIE System6 t This test method is under the jurisdiction of ASTM Committee DI6 on Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of Subcommittee DI6.0E on Instrumental Analysis. Current edition approved Sept. 15 and Oct. 15, 1993. Published December 1993. Originally published as D 5386 - 93. Last previous edition D 5386 - 93. 2 Annual Book of ASTM Standards, Vols 06.01 and 11.01. 3 Annual Book of ASTM Standards, Vol 06.04. 4 Annual Book of ASTM Standards, Vol 08.02. Annual Book of ASTM Standards, Vol 15.05. 6 Annual Book of ASTM Standards, Vol 06.01.
E 450 Method for Measurement of Color of Low-Colored Clear Liquids Using the Hunterlab Color Difference Meter7 E 691 Practice for Conducting an Interlaboratory Study to Determine the Precision of Test Methodss 2.2 Other Document: OSHA Regulations, 29 CFR, paragraphs 1910.1000 and 1910.12009 3. Summary of Test Method 3.1 Color is measured by tristimulus values of light transmitted by a sample as percent of light transmitted by distilled water. Convert the measured tristimulus values by appropriate equations to the platinum-cobalt scale. 4. Significance and Use 4.1 The major objective of the visual platinum-cobalt (Pt-Co) method of color measurement, as defined in Test Method D 1209, is to rate specific materials for yellowness. This yellowness is frequently the result of the undesirable tendency of liquid hydrocarbons to absorb blue light due to contamination in processing, storage or shipping. 4.2 Clear liquids can be rated for light absorbing yellowish or brownish contaminants, using scales that simulate the long-established visual-comparison method just cited. Where needed, dimensions of color can be reported to identify any pinkness or greenness (one dimension), or grayness. 5. Apparatus 5.1. Instrument, with the following provisions: 5.1.1 Instrument Sensor, shall provide a beam for illuminating the sample cell in transmission. The instrument shall be capable of converting fight measured in total transmission through the sample cell to CIE X Y Z tristimulus color values for the measurement conditions of CIE illuminant C and the CIE 1931 2 degree standard observer as described in Practices E 179 and Test Method E 308. 5.1.2 The CIE X Y Z tristimulus color values shall be convertable to the instrumental yellowness index (Y1) defined by Test Method D 1925 and Test Method E 308. A correlation between measured yellowness index (3(I) (Test Method D 1925) values and the Pt-Co standard solutions shall be used to yield an equivalent instrumental Pt-Co rating for liquid hydrocarbon samples. 7 Discontinued 1993; see 1992 Annual Book of ASTM Standards, Vol. 15.05. s Annual Book of ASTM Standards, Vols 06.04 and 14.02. 9 Available from the Superintendent of Documents, U.S. Government Printing Office, Washington, D e 20402.
880
~ D 5386 5.1.3 Sample Cells, shall have clear, colorless, parallel entrance and exit windows. Internal distance between faces shall be selectable. Pathlengths from 20 mm to 150 mm have been used for near-clear liquid hydrocarbons. If measuring samples using cells of the same pathlength, a pathlength tolerance of +3 % or less would be appropriate. Matched cells would be beneficial but not required.
6. Reagents
6.1 Purity of Reagents--Reagent grade chemicals shall be used in all tests. 6.2 Purity of Water--References to water shall be understood to mean colorless distilled Water, conforming to Type IV of Specification D 1193. 6.3 Cobalt Chloride, (CoC12.6H20). 6.4 Hydrochloric Acid (sp gr I. 19)--Concentrated hydrochloric acid (HCI). 6.5 Potassium Chloroplatinate, (K2ItC16). 6.6 Platinum-Cobalt Stock Solution--Dissolve 1.245 g of potassium chloroplatinate (K2PtCIt) and 1.00 g of cobalt chloride (CoCI2 H20) in water. Carefully add 100 mL of hydrochloric acid (HCI sp gr 1.19) and dilute to 1 L with distilled water. The absorbance of the 500 platinum-cobalt stock solution in a cell having a 10-ram light path with distilled water in a matched cell as the reference solution must fall within the limits given in Table 1. 7. Materials
7.1 Platinum-Cobalt Standards--From the stock solution prepare color standards in accordance with Table 2 by diluting the required volumes to 100 mL with water in volumetric flasks. When properly sealed and stored these standards are stable for at least one year. 8. Hazards 8.1 Consult current OSHA regulations and suppliers' Material Safety Data Sheets for all materials used in this test method. TABLE 1
Abaorbance Tolerance Limits for No. 500 PlatinumCobalt Stock Solution
Wavelength
Absorbance
430 455 480 510
0.110 to 0.120 0.130 to 0.145 0.105 to 0.120 0.056 tO 0.065
TABLE 2
Platinum-Cobalt Colar Stsndarda
Color Standard Number
Stock Solution, mL
1 2 3 4 5 6 7 8 9
0.20 0.40 0.60 0.60 1.00 1.20 1.40 1.60 1.80
Cokx Standard Stock Solution mL Number 10 11 12 13 14 16 20 25 30
2.00 2.20 2.40 2.60 2.80 3.00 4.00 5.00 6.00
9. Sampling and Handling 9.1 Refer to Practice D 3437 for proper sampling and handling of liquid hydrocarbons analyzed by this test method. 10. Calibration 10.1 Prepare instrument for operation by following the instrument manufacturer's instructions. 10.2 Use instrument standardizing adjustments or program to obtain a It-Co value of 0 for a sample of distilled water. 10.3 Measured on a regular basis an intermediate It-Co standard solution in the It-Co range of the samples being analyzed, would verify instrumental performance. It is desirable for the user to be able to adjust the instrument to match the It-Co standard solutions as defined in 7.1. 11. Procedure 11. l Check to be sure that the instrument is operating in accordance with the manufacturer's operations manual. 11.2 Take three (3) instrumental readings without sample replacement, with the average taken as being a representative It-Co measurement of the sample. Exercise care to avoid sample contamination. 12. Report 12. l Report the following information: 12.1. l Sample identification, and 12.1.2 Instrumental It-Co measurement to nearest whole unit. 13. Precision and Bias 1°
13.1 Precision--The data for determining the precision of this test method are based on the analyses of o-xylene, styrene, and toluene at approximate values of 4, 8 and 12 respectively. Solutions prepared at levels of approximately 5, 10, 15 and 25 It-Co units were also included in the round robin. 13.2 Under the guidelines of Practice E 691, the following criteria should be used to judge the acceptability (95 % probability) of results obtained by this test method. The criteria were derived from a round robin between ten laboratories. Each one of the seven samples was run on two different days in each laboratory. 13.2.1 Repeatability--Two single test results obtained from the same laboratory should not be considered suspect unless they differ by more than 0.9 It-Co units. 13.2.2 Reproducibih'ty--Two single test results obtained from different laboratories should not be considered suspect unless they differ by more than 2.0 It-Co units. 13.3 Bias--The bias of this test method cannot be determined because no referee method is available to determine the true value. 14. Keywords 14. I color; hydrocarbons; platinum-cobalt; tristimulus io Supporting data are available from ASTM Headquarters. Request RR:DIt. 1012.
881
q~) D 5386 The American Society for Testing and Materiels takes no position respecting the validity of any patent rights asserted In connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the vatldlty of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision st any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received s fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
882
q~
Designation:D 5442 - 93 Standard Test Method for Analysis of Petroleum Waxes by Gas Chromatography 1 This standard is issued under the fixed designation D 5442; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsiion (~) indicates an editorial change since the last revision or rcapproval.
3.1.1 carbon number--a number corresponding to the number of carbon atoms in a hydrocarbon. 3.1.2 cool on-column injection--a sample introduction technique in gas chromatography where the sample is injected inside the front portion of a partition column at a temperature at or below the boiling point of the most volatile component in the sample. 3.1.3 low volume connector--a metal or glass union designed to connect two lengths of capillary tubing. Usually designed so that the tubing ends are joined with a minimum of either dead volume or overlap between them. 3.1.4 non(normal para~n)hydrocarbon (NON)--aU other hydrocarbon types excluding those hydrocarbons with carbon atoms in a single length. Includes aromatics, naphthenes, and branched hydrocarbon types. 3.1.5 normal paraffin--a saturated hydrocarbon which has all carbon atoms bonded in a single length, without branching or hydrocarbon rings. 3.1.6 wall coated open tube (WCOT)wa term used to specify capillary columns in which the stationary phase is coated on the interior surface of the glass or fused silica tube. Stationary phase may be cross-linked or bonded after coating.
1. Scope 1.1 This test method covers the quantitative determination of the carbon number distribution of petroleum waxes in the range from n-Cl7 through n-C44 by gas chromatography using internal standardization. In addition, the content of normal and non.normal hydrocarbons for each carbon number is also determined. Material with a carbon number above n-C44 is determined by difference from 100 mass % and reported as C45+. 1.2 This test method is applicable to petroleum derived waxes, including blends of waxes. This test method is not applicable to oxygenated waxes, such as synthetic polyethylene glycols (for example, Carbowax2), or natural products such as beeswax or carnauba. 1.3 This test method is not directly applicable to waxes with oil content greater than 10 % as determined by Test Method D 721. 1.4 The values stated in SI units are to be regarded as the standard. 1.5 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Notes 1 and 2.
4. Summary of Test Method 4.1 Weighed quantities of the petroleum wax and an internal standard are completely dissolved in an appropriate solvent and introduced into a gas chromatographic column that separates the hydrocarbon components by increasing carbon number. The column temperature is linearly increased at a reproducible rate until the sample is completely eluted from the column. 4.2 The eluted components are detected by a flame ionization detector and recorded on a strip chart or computer system. The individual carbon numbers are identified by comparing the retention times obtained from a qualitative standard with the retention times of the wax sample. The percent of each hydrocarbon number through C~ is calculated via internal standard calculations after applying response factors. 4.3 For samples with final boiling points greater than 538°C complete elution of all components may not be achieved under the specified conditions. For this reason, the C45+ material is determined by summing the concentrations of each individual carbon number through C~ and subtracting this total from 100 mass %.
2. Referenced Documents
2.1 ASTM Standards: D 721 Test Method for Oil Content of Petroleum Waxes3 D 4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards 4 D4419 Test Method for Determination of Transition Temperatures of Petroleum Waxes by Differential Scanning Calorimetry4 D 4626 Practice for Calculation of Chromatographic Response Factors* E 260 Practice for Packed Column Gas Chromatography 5 E 355 Practice for Gas Chromatography Terms and Relationships 5 3. Terminology 3.1 Descriptions of Terms Specific to This Standard: This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.04.0L on Gas Chromatography. Current edition approved Dec. 15, 1993. Published February 1994. 2 Carbowax is a registered trademark of Union Carbide Corp. 3 Annual Book of ASTM Standards, Vol 05.01. 4 Annual Book of ASTM Standards, Vol 05.02. 5 Annual Book of ASTM Standards, Vol 14.01.
5. Significance and Use 5.1 The determination of the carbon number distribution of petroleum waxes and the normal and non-normal hydrocarbons in each can be used for control of production 883
~
D 5442
processes as well as a guide to performance in many end UseS.
5.2 Data resulting from this test method are particularly useful in evaluating petroleum waxes for use in rubber formulations. 6. Apparatus 6.1 Chromatograph--Any gas chromatographic instrument that can accommodate a WCOT column, equipped with a flame ionization detector (FID), and that can be operated at the conditions given in Table 1 may be employed. The chromatograph should be equipped with a cool on-column inlet (or equivalent) for introducing appropriate quantities of sample without fractionation. In addition, the gas chromatograph must be capable of generating a chromatogram where the retention times of an individual peak have retention time repeatability within 0.1 min. Refer to Practices E 260 and E 355 for general information on gas chromatography. 6.2 Sample Introduction System--Any system capable of introducing a representative sample onto the front portion of a WCOT column may be employed. Cool on-column injection is preferred, however other injection techniques can be used provided the system meets the specification for linearity of response in 9.6. For cool on-column injection, syringes with 0.15 to 0.25 mm outside diameter needles have been used successfully for columns 0.25 mm inside diameter or larger and standard 0.47 mm outside diameter syringe needles have been used for columns 0.53 mm inside diameter or greater. 6.2.1 Care must be taken that the sample size chosen does not allow some peaks to exceed the linear range of the detector or overload the capacity of the column. 6.3 Column(s)--Any column used must meet the chromatographic resolution specification in 9.5. WCOT columns with 25 to 30 m lengths and a stationary phase coating of methyl siloxane or 5 % phenyl methyl siloxane have been successfully used. Cross-linked or bonded stationary ~hases are preferred. 6.4 Recorder--A recording potentiometer or equivalent TABLE 1 Typical Operating Conditiona Column length (m): 25 Column inside 0.32 diameter (ram): Stationary phase: DB-1 methyl silicone Film thickness ~m): Carder gas: Carder flow (mL/min): Linear velocity
30 0.53
15 0.25
RTX-1 methyl silicone
0.25
0.25
DB-5 5 Y, phenyl methyl silicone 0.25
Helium 1.56
Helium 5.0
Helium 2.3
33
35
60
80
80
8
5
340
350
cool on-column 400
cool on-column 375
1.0
1.0
(era/s): Column Initial 80 temperature (eC): Program rate 10 (*C/mln): Final temperature 380
(*C): Injection technique: cool on-column Detector tern380 perature (*C): Sample size (/.tL): 1.0
884
with a full-scale deflection of 5 mV or less for measuring the detector signal versus time. Full scale response time should be 2 s or less. Sensitivity and stability should be sufficient to generate greater than 2 mm recorder deflection for a hydrocarbon injection of 0.05 mass % under the analysis conditions employed. 6.5 Integratoror Computer--Means must be provided for integrating the detector signal and summing the peak areas between specific time intervals. Peak areas can be measured by computer or electronic integration. The computer, integrator, or gas chromatograph must have the capability of subtracting the area corresponding to the baseline (blank) from the sample area, and have the ability to draw the baselines used for peak area integration. 7. Reagents and Materials
7.1 Carrier Gas--Carrier gas appropriate for the flame ionization detector. Hydrogen and helium have been used successfully. The minimum purity of the carrier gas used should be 99.95 mol%. NOTE h Wm'nlng--Hydrogen and helium are compressed gases under high pressure. Hydrogenis an extremelyflammablegas. 7.2 n-hexadecane--Hydrocarbon to be added to samples as an internal standard. Minimum purity of 98 % is required. 7.3 Standards for Calibration and Identification--Standard samples of normal paraffins covering the carbon number range (through C~) of the sample are needed for establishing the retention times of the individual paraffins and for calibration for quantitative measurements. Hydrocarbons used for standards must be greater than 95 % purity. 7.4 Solvent--A liquid (99 % pure) suitable for preparing a quantitative mixture of hydrocarbons and for dissolving petroleum wax. Cyclohexane has been used successfully. NOTE 2: Warning--Solvents are flammable and harmful ff inhaled. 7.5 Linearity Standard--Prepare a weighed mixture of n-paraffins covering the range between n-C=6 to n-C44 and dissolve the mixture in cyclohexane. Use approximately equal amounts of each of the paraffins and a balance capable of determining mass to within 1% of the mass of each compound added. It is not necessary to include every n-paraffin in this mixture so long as the sample contains n-Cl6, n-C44, and at least one of every fourth n-paraffin. It will be necessary to prepare the standard sample in cyclohexane, so that the normal paraffins are completely dissolved in the solvent. Solutions of 0.01 mass % n-paraffin have been used successfully. This sample must be capped tightly, to prevent solvent loss which will change the concentration of paraffins in the standard blend. NOTE 3--Refer to Practice D 4307 for details of how to prepare hydrocarbon mixtures. 7.6 Internal Standard Solution--Prepare a dilute solution of internal standard in cyclohexane in two steps as follows: 7.6.1 Prepare a stock solution containing 0.5 mass % n-C~6 in cyclohexane by accurately weighing approximately 0.4 g n-Ct6 into a 100 mL volumetric flask. Add 100 mL of cyclohexane and reweigh. Record the mass of n-Ci6 to within 0.001 g and the mass of solution (cyclohexane and n-Cmt) to within 0.1 g. 7.6.2 Prepare a dilute solution of n-C~6 internal standard
~
D 5442 9.3.1 Baseline Bleed--Observe the detector response from the blank run on the recorder. Some increase in detector response will be observed at the upper column temperatures due to stationary phase bleed. Column bleed is acceptable so long as the duplicate baseline blank analyses are repeatable. The baseline should be a smooth curve, free of any chromatographic peaks. 9.4 Solvent Blank--Make a 1 ~tL injection of the cyclohexane solvent and program the column oven. The solvent is of suitable purity if there are no detected peaks within the retention time range over which the wax samples elute. 9.5 Column Resolution--Check the efficiency of the G-C column by analyzing, under conditions specified in 10.2, a 1 IxL injection of 0.05 mass % solution of n-C2o and n-C24 in cyclohexane. The column resolution must not be less than 30 as calculated using Eq 2. 2d R = 1.699(W1 + W'2) (2)
by diluting one part of stock solution with 99 parts of cyclohexane. Calculate the concentration of internal standard in the dilute solution using Eq 1.
CisTD ffi where: Czsro l,Vtsro Ws 100 % 100
WzsrD 1O0 % x Ws 100
(1)
= mass % n-C~6 internal standard in dilute solution, = weight of n-Cl6 from 7.6.1, = weight of cyclohexane plus n-C16 from 7.6.1, ffi factor to convert weight fraction to mass %, and ffi dilution factor.
8. Sampling 8.1 To ensure homogeneity, completely mix the entire wax sample by heating it to 10*C above the temperature at which the wax is completely molten and then mix well by stirring. Using a clean eyedropper, transfer a few drops to the surface of a clean sheet of aluminum foil, allow to solidify and break into pieces. The wax can either be used directly as described in Section 11 or placed in a sealed sample vial until ready for use. 8.1.1 Aluminum foil usually contains a thin film of oil from processing. This oil must be removed by rinsing the foil with solvent such as hexane or mineral spirits, prior to use.
where: d = distance (mm) between the peak maxima of n-C2o and n-C24, W1 ffi peak width (mm) at half height of n-C2o, and W2 ffi peak width (ram) at half height of n-C24. 9.6 Linearity of Response--For quantitative accuracy, detector response must be proportional to the mass of hydrocarbon injected, and the response of the non-normal paraffins is assumed to be equivalent to the response of the n-paraffin with the same carbon number. In addition, sample injection technique and sample solution properties must be such that representative sample is introduced to the gas chromatograph without discrimination. Before use, the analysis system must be shown to conform to these requirements as specified in 9.6.1. 9.6.1 Analyze the linearity standard described in 7.5 and calculate the relative mass response factors according to Practice D 4626. Response factors calculated relative to hexadecane must be between 0.90 and 1.10. 9.6.2 If relative response factors are not within the limits stated above, take appropriate action and reanalyze the lincarity standard to ensure linearity and the absence of discrimination. 9.7 Retention Time Repeatability---Check the retention time repeatability by analyzing the linearity standard in duplicate. Retention times for duplicate analyses must not differ by more than 0.10 rain between duplicate runs.
9. Preparation of Apparatus 9.1 Column Conditioning--Capillary columns with bonded (or cross-linked) stationary phases do not normally need to be conditioned; however, it is good chromatographic practice to briefly condition a new column as described below. 9.1.1 Install the column in the chromatographic oven and connect one column end to the sample inlet system. Turn on the source of carrier gas and set the flow controller (or pressure regulator) to the flow rate to be used in the analysis. Increase the column temperature to the maximum value to be used in the analysis and maintain this temperature for 30 min. Cool the column temperature to room temperature and connect the remaining column end to the detector. Care must be taken that the column terminates as dose as possible to the tip of the l i D jet. The temperature of the column between the column oven and the detector jet must be maintained above the maximum column temperature. 9.2 Operating Conditions--Set the chromatographic operating conditions (see Table 1) and allow the system to achieve all temperature setpoints. The recorder, computer or integrating device should be connected so that a plot of the detector signal vs time can be obtained. Make certain that the FID is ignited before proceeding. 9.3 Baseline Blank--After conditions have been set to meet performance requirements, program the column temperature upward to the maximum temperature to be used. Once the column oven temperature has reached the maximum temperature, cooI the column to the selected starting temperature. Without injecting a sample, start the column temperature program, the recording device and the integrator. Make two baseline blank runs to determine if the baseline blank is repeatable. If the detector signal is not stable or if the baseline blanks are not repeatable, then the column should either be conditioned further or replaced.
10. Calibration and Standardization 10.1 n-Para~n Identification--Determine the retention time of each n.paraffin in the range from Cl~ to C~ by injecting small amounts of each paraffin either separately or in known mixtures. Completely dissolve samples in cyclohexane. 10.2 Standardization--Inject the linearity standard described in 7.5 and measure the peak area of each n-paraffin by electronic integrator or computer. 10.2.1 Calculate the response per unit mass of the detector for each component in the linearity standard, relative to n-C16, according to Practice D 4626. 885
~
D 5442
11. Procedure 11.1 Prepare a solution of the petroleum wax sample for analysis as follows: 11.1.1 Obtain a petroleum wax sample specimen as directed in 8.1. 11.1.2 Accurately weigh about 0.0100 g of the wax specimen into a glass vial of approximately 15 mL capacity. Add approximately 12 mL of the dilute internal standard solution (0.005 mass % n-C,6 in cyclohexane), cap the vial and determine the exact weight of dilute internal standard solution added. Record both weights. 11.1.3 Agitate the vial until the wax is dissolved, using genre heating if necessary. 11.1.4 For manual syringe injections, fill the syringe directly from this vial. For automatic syringe injections, transfer a suitable aliquot to the appropriate autosampler vial. 11.2 Before analyzing wax samples, program the column temperature to the maximum temperature used. Once the column temperature has reached the maximum, cool the column to the selected starting temperature, and allow it to equilibrate at this temperature for at least 3 rain. Without injecting any material, initiate a blank run by starting the temperature program, recorder, and integrator and allow to continue until at least 2 rain after the retention time of n-C~. Store a record of this blank run in the computer or integration device for subtraction from the sample area. Note 4--Some commercially available gas chromatographs have software routines as part of their standard systems to make the baseline correction directly to the detector signal. With such systems, no computer subtraction of the blank is necessary. 11.3 Following the same procedure as for the blank run (see 11.2), inject 0.5 to 1.0 ttL of the wax sample solution from 11.1 into the cool on-column injection port. Immediately start the temperature program, the recorder, and the integrator, and store the acquired detector signal. 11.4 Integrate the stored detector signal twice, using the baseline construction parameters as directed below. 11.4.1 Using a valley to valley baseline construction,
integrate the detector signal to obtain an area (see Fig. 1) for each peak in the chromatogram. Based on the retention times determined in 10.1, identify the normal paraffin peaks and tabulate only their areas. Also record the area of the n-C16 (hexadecane) internal standard peak that must be completely resolved (baseline separation) from the wax sample area. 11.4.2 Using a vertical drop to a horizontal baseline construction (see Fig. 2), integrate the detector signal a second time. Sum the area of all the peaks of each carbon number and tabulate these totals. By convention, the peaks assigned the carbon number n are those that elute between the valley immediately following the normal paraffin peak (C,q) and the corresponding valley following the next normal paraffin peak (C,). 11.4.3 To ensure proper and consistent integrations, plot the chromatogram with drawn in baseline after each integration and confirm that the baselines match Figs. 1 and 2. 11.4.4 Do not include, as part of the sample, any peaks resulting from the solvent or the internal standard. NOTE 5--The total area for each carbon number can be measuredby either pre-programming the integrator to sum the area of the peaks within the appropriate retention time windowsor by analyzing the peak area data al~r the peak integration processis complete. 12. Calculation 12.1 Each Carbon NumberwCalculate the mass % for each carbon number determined in 11.4.2 using Eq 3. AreaI C, . . ~
Arealsr~
MIX × RRF, ×
sample
C, areal
ffi mass % of hydrocarbons with carbon number i, = area sum of hydrocarbons with carbon number
i, arealsrD ffi area of n-C16 internal standard peak,
RRFi
= response factor, relative to n-Cnt,
MIX
= weight of dilute internal standard/solvent mix-
ture,
8.80
7.18
5.57
3.9~
! t J..0O.
I 14.62
!
! t 8 . P5
I 21 . 8 7
!
I 25.50
!
I 29 • t2
!
I 63q7t5 I 32.75 36.37
manures
FIG. 1
(3)
where:
t0.42
2.3
× C1sn,
Valley to Valley Integration for Area of Normal Paraffin
886
! 4 0 . O0
~) D 5442 3.5C
32~_ 3.0~
~.
2.rap
L ........... 2.6E
I
2.44 ~ 24.00. minutes
l a4.25
FIG. 2
,
I
•
_
24.50
I--_,
I
24.75
~
I---
25.00
,
25.25
I
,
25.50
I
25.74
a6.oo
C a r b o n N u m b e r S u m m a t i o n (Vertical D r o p to H o r i z o n t a l B a s e l i n e )
3.50 _
3.28 _
3.07 _
2.o~
,
24,.00. mlnutes
24.25
I
.-~-----
24.75
24.50
FIG. 3
I
X
CisTD
, __---L-
___~-.-..
;25.50
I
25.75
L~6.O0
MIX
ffi weight of dilute internal standard/solvent mixture, sample ffi weight of wax sample, and CzsrD = mass % of n-Ci6 in internal standard mixture. 12.3 Non-Normal Paraffin HydrocarbonnThe nonnormal paraffin hydrocarbons arc calculated as the difference between the mass percent of hydrocarbons with carbon number i (Cl) and the mass percent of the n-para~n with carbon number i (N;):
(4)
where:
N,
A
25.25
Typical Wax Chromatogram
sample = weight of wax sample, and CIsrD = mass % of n-C~6 in internal standard mixture. 12.2 Normal ParaffinwCalculate the mass % of each normal paraffin hydrocarbon from the individual areas determined in 11.4.1 using Eq 4. Areai MIX =- X RRFj X - Nt Areals-rD sample
,
25. O0
ffi mass % of normal paraffin with carbon number
NON,
i,
= C,- N I
(5)
where:
areai
= peak area of normal paraffin with carbon number i, arealsrD = area of n-C~s internal standard peak, RRF, -- response factor, relative to n-C~6,
mass percent of the non-normal paraffin hydrocarbons of each carbon number. 12.3.1 The response for all components in a carbon number is assumed to be the same as the response for the
NON(O
887
=
~h~ D 5442 TABLE 2
normal paraffin of the same carbon number as determined in 10.2. 12.3.2 Relative response factors for individual n-paraffins between those determined from the calibration mixture are obtained by interpolation. 12.4 Calculate the mass percent of C45+ according to Eq 6: mass % C45+ = 100 % - 7.Ct (6)
Repeatability and Reproducibility
Carbon Number Range,mass ~ C21 C=~ C=e C=o C~ C~ C= C41 C,~ Total n-paraffins
where: 2;C~ = the sum of the mass % of all detected hydrocarbons.
0.11-0.25 0.04-2.90 0.01-8.94 0.04-8.15 0.44-5.05 2.52-5.62 0.44-3.61 0.06-2.96 0.02-2.26 18.73-79.52
Repeatal~ty ~ 0.014 0.0463X°.~° 0.0785X°'se 0.0872X°~1 0.1038X°-s° 0.1737X 0.1131(X + 0.1069) 0.1600 X 0.4990X°'e° 2.64
ReproductbUity A 0.039 0.1663 X°'3° 0.4557 X°'~ 0.3984 X°'ca 0.6472 X°'s° 0.4540 X 0.6476(X + 0.1069) 0.6460 X 0.9220 X°'e° 26.03
A Where X is the mass percent of the component.
13. Report 13.1 Report the concentration in mass percent of the normal (Ni) and non-normal ( N O N i) hydrocarbons for each carbon number in the sample to the nearest 0.01 mass percent. Report also the amount of residual as % C45+.
test material, would, in the long run, in the normal and correct operation of the test method, exceed the values in Table 2 only in one case in twenty. 14.1.2 Reproducibility--The difference between two single and independent results, obtained by different operatots working in different laboratories on identical test materials would, in the long run, in the normal and correct operation of the test method, exceed the values in Table 2 only in one case in twenty. 14.2 Bias--Bias cannot be determined because there is no reference material suitable for determining the bias of the procedure in this test method.
14. Precision and Bias6 14.1 Precision--The precision of this test method as determined by statistical examination of intedaboratory test results is as follows: 14.1.1 Repeatability.--The difference between the two test results, obtained by the same operator with the same apparatus under constant operating conditions on identical
15. Keywords 15.1 gas chromatography; non-normal paraffin hydrocarbons; normal paraffin; paraffin wax; petroleum wax
6 Supporting data is available from ASTM headquarters. Request RR:D021316,
888
~
D 5442
The American Society for Testing and Materials takes no posit/on respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that daterrnlnaticn of the validity of any such patent rights, and the risk of infringement of such rights, a r e entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and ff not revised, either respproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received e fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
889
(~T~ Designation: D 5443 - 93
Standard Test Method for Paraffin, Naphthene, and Aromatic Hydrocarbon Type Analysis in Petroleum Distillates Through 200°C by Multi-Dimensional Gas Chromatography 1 This standard is issued under the fixed designation D 5443; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last re.approval. A superscript epsilon (E) indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 This test method provides for the determination of paraffins, naphthenes, and aromatics by carbon number in low olefinic hydrocarbon streams having final boiling points of 200"C or less. Hydrocarbons with boiling points greater than 200"C and less than 270"C are reported as a single group. Olefins, if present, are hydrogenated and the resultant saturates are included in the paraffin and naphthene distribution. Aromatics boiling at Ca and above are reported as a single aromatic group. 1.2 This test method is not intended to determine individual components except for benzene and toluene that are the only C6 and C7 aromatics, respectively, and cyclopentane, that is the only C s naphthene. The lower limit of detection for a single hydrocarbon component or group is 0.05 mass %. 1.3 This test method is applicable to hydrocarbon mixtures including virgin, catalytically converted, thermally converted, alkylated and blended naphthas. 1.4 The values stated in SI (metric) units are to be regarded as the standard. 1.5 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Notes 1 and 2 and Table 2.
hydrogenates olefins, if present, in this fraction, and then to a molecular sieve column which performs a carbon number separation based on molecular structure, that is, naphthenes and paraffins. The fraction remaining on the polar column is further divided into three separate fractions that are then separated on a non-polar column by boiling point. Eluting compounds are detected by a flame ionization detector. 3.2 The mass concentration of each group is determined by the multiplication of detected peak areas by flame ionization detector response factors and normalization to 100 %. 4. Significance and Use 4.1 A knowledge of the composition of hydrocarbon refinery streams is useful for process control and quality assurance. 4.2 Aromatics in gasoline are soon to be limited by federal mandate. This test method can be used to provide such information. 5. Interferences 5.1 Chemicals of a non-hydrocarbon composition may elute within the hydrocarbon groups, depending on their polarity, boiling point, and molecular size. Included in this group are ethers (for example, methyl-tertiary butyl ether) and alcohols (for example, ethanol). 6. Apparatus 6.1 Chromatograph--A gas chromatograph capable of isothermal operation at 130 -4-0. I*C. The gas chromatograph must contain the following: 6.1.1 A heated flash vaporization sample inlet system capable of operation in a splitless mode. 6.1.2 Associated gas controls with adequate precision to provide reproducible flows and pressures. 6.1.3 A flame ionization detection system optimized for use with packed columns and capable of the following:
2. Referenced Documents
2. l ASTM Standards: D4057 Practice for Manual Sampling of Petroleum and Petroleum Products 2 D 4307 Practice for Preparation of Liquid Blends for Use As Analytical Standards 2 3. Summary of Test Method 3.1 A representative sample is introduced into a gas chromatographic system containing a series of columns and switching valves. As the sample passes through a polar column, the polar aromatic compounds, bi-naphthenes, and high boiling (>200"C) paraffins and naphthenes are retained. The fraction not retained elutes to a platinum column, that
Isothermal temperature operation . . . . . . . . . . . . Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Minimum detectability . . . . . . . . . . . . . . . . . . . . . . Linearity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
150 to 170"C >0.015 coulombs/g 5 × 10-12 g carbon/second >107
Some instruments will produce a non-linear response for benzene, above approximately 5.5 mass %, and for toluene above approximately 15 mass %. The linearity of these components above these concentrations must be verified with appropriate blends. Where non-linearity has been shown to exist, samples, that contain no higher than C~3, can be analyzed if the sample is diluted with n-Cm5 and the
s This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.04.0L on Gas Chromatography. Current edition approved Aug. 15, 1993. Published October 1993. "Annual Book of ASTM Standards, Vol 05.02.
890
~) O 5443 TABLE 1 Specifw,ation
Typical Column
Specifications Column Type
Polar
Non-Polar
Tenaxa
4 1.8 to 2.0 OV-101 c 4-5 Chromasorb ° WAW __.
0.16 to 0.18 2.5
Packing material
3 2.0 to 2.1 OV-275 B 30 Chromasorb o PAW __.
:renaxa
M~ecular sieve 13X e'~=
Mesh size
60/80
80/100
80/100
.
Column length, m Column inside diameter, mm Liquid phase Percent liquid phase Support matarlal
. .
. .
.
.
Molsieve A
. .
.
Ratinum A
1.8 1.6 to 2.0 . .
.
. .
.
0.002 to 0.06 1.6
. .
.
.
. .
. .
.
.
. .
.
.
.
.
... ... .
A See Footnote 4 for commercial columns availability. a See Footnote 8 for information on 0V-275. c See Footnote 8 for Information on OV-101. o See Footnote 9 for information on Chromasorb. e Sodium form of molecular sieve 13X. F May also contain a mix of molecular sieves 13X and 5A to separate normal and iso-peraffins.
instrument is equipped with a prefractionating column. The sample may also be diluted with a component that is not present in the sample and this component will then not be included in the normalized report. 6.2 Sample Introduction System--Manual or automatic liquid sample system operated in a splitless mode. Although this test method is intended primarily for use with syringe sample injection, automatic sampling valves have also been found satisfactory. Devices capable of a reproducible injection volume of 0.1 to 0.5 pL are suitable. The sample introduction system must be capable of heating the sample to a temperature that ensures total sample vaporization. A temperature range of 120 to 180°C has been found suitable. 6.3 ElectronicData Acquisition System--The data acquisition and integration device used for detection and integration must meet or exceed the following specifications: 6.3.1 Capacity for at least 75 peaks for each analysis, 6.3.2 Normalized area percent calculation, 6.3.3 Noise and spike rejection capability, 6.3.4 Sampling rates for fast (200C Type Carbon Number
NIPINI ~ , 6
7
INIPINIP[ 8
9
10
,'~C,
11
FIG. 15
Number of Carbon Atoms
Paraffins
3 4 5 6
0.916 0.906 0.899 0.896
(3:874 0.874
0.811
7
0.692
0.674
0.620
6 9 10 11
0.890 0.888 0.887 0.886
0.874 0.874 0.874 0.874
0.827 0.835 ... ...
.
.
.
.
8,9.10
TABLE 9
Repeatability and Reproducibility for Selected Naphtha Components and Groups of Components
Component or Group
Aromatics .
Aromotlcl
7,8,9
Q u a l i t a t i v e N a p h t h a Sample
TABLE 8 Flame Ionization Detector Response Factors Based on Percentage by Mass of Carbon, Methane Used as Unity Naphthenes
Aromc,~
6,7
. ...
ment resulting from the application of this test method depends on several factors related to the individual or group of components including the volatility, concentration and the degree to which the component or group of components are resolved from closely eluting components or groups of components. As it is not practical to determine the precision of measurement for every component or group of components at different levels of concentration separated by this test method, Table 9 presents the repeatability and reproducibility values for selected, representative components and groups of components. 14.1.1 RepeatabilitymThe difference between successive test results obtained by the same operator and same apparatus under constant operating conditions on identical test materials would, in the long run, in the normal and correct operation of the test method, exceed the repeatability values shown in Table 9 only one case in twenty. 14.1.2 ReproducibilitymThe difference between two
898
Repeatability A
ReWoducibllityA
Benzene
0.0~x)o.m
Toluene
0.051(x)°.aT
0.22(x)o.a7
Ce Aromatl~ Co+ Arornatk= C,v Paraffins Ce Paraffins Co Paraffin8
0.041(x) 0.092(xp.eo 0.005(x)°-s° 0.098(x)o-so
0.17(x) 0.50(x)o.so 0.61 "/, 0.18(x)°.s° 0.17(x)O-SO
Co Naphthenes
0.046(x)°-s°
0.1 l(x)°.5°
C7 Naphthenes Ce Naphtherm Total paraffins Total naphther~ Total aromatics
0.14(x) 0.067(xp.~
0.33(x) 0.13(x) °,as
0.059(x) °-s° 0.077(x) o-so
0.11 (x)°-s° 0.28(x)O~O
0.16 "/,
0.064(x)o.8o
0.~)(x)o=o
0.17(x)O.6O
A (x) Refers to the mass percent of the componentor group of components found.
single and independent test results obtained by different operators working in different laboratories on identical test materials would, in the long run, in the correct operation of this test method, exceed the values shown in Table 9 only one case in twenty. 14.1.3 Bias--Bias is the measurement resulting from the application of this test method cannot be determined since there is no accepted reference material suitable for determining bias. 15. Keywords 15.1 aromatics; gas chromatography; hydrocarbon type; multi-dimensional; naphthenes; paraffins; petroleum distillates
~)
D 5443
ANNEX
(Mandatory Information) A1. CALCULATION AND REPORTING OF LIQUID VOLUME PERCENT A I.I Calculate and report the liquid volume percent of each hydrocarbon type group normalized to 100 %, using the normalized mass percent data as calculated in 12.1 and 12.2 and the average relative density of each hydrocarbon type group from Table A I. I. AI.2 Use an average relative density factor of 0.8000 for the first three fractions boiling above 200"C. Use an average relative density factor of 0.8800 for the last fraction boiling above 200"C. Use an average relative density factor of 0.8762 for (29 and above aromatics. A I.3 Divide each of the hydrocarbon group type mass percent data, as reported in 12.1, 12.2, and 12.3 by the appropriate average relative density factor to produce the corrected liquid volume percent for each of the identified groups:
D,,
(ALl)
where: Vi~ --corrected liquid volume percent of an identified group, M, = normalized mass percent of an identified group, and D a -- average relative density of an identified group. A I.4 Add all of the individual, corrected liquid volume percent data from A 1.2 to produce the total corrected liquid volume percent: T , = Z V~c (AI.2) where: 7", = total corrected liquid volume percent. AI.5 Divide each of the corrected liquid volume percent data for each identified group from AI.3 by the total of the
TABLE A1.1 AverageRelaUve 15/150C Density of Hydrocarbon Type GrouplA Number of Carbon
Atoms
Paraffins
Naphthenes
3 4
0.5070 0.5735
.
.
.
5 6 7 8 , 10
0.6177 o. 22 0.6.11 07143 0.7318 07,26
0.7603 07 8 0.78.8 0.7788 08058 o817.
11
0.7445
0.8200
.
Aromatics .
. ~
_
t
°
B
_
_
0 29 087 0.87 08782 ...
A See Footnote 6.
corrected liquid volume percent data from A1.4 to produce the normalized liquid volume percent for each identified group:
T,
(AI.3)
where: Vi = normalized liquid volume percent of an identified group. AI.6 Report the liquid volume percent and hydrocarbon group type of each group through Cjl to the nearest 0.01%. AI.7 Report the liquid volume percent of the fraction boiling above 200"C to the nearest 0.01%. A1.8 Report the liquid volume percent of the polynaphthenes boiling below 200"C (for example, transDecahydronaphthalene) to the nearest 0.01%. A I.9 Report the liquid volume percent of the C9 and above aromatics as C9+ aromatics to the nearest 0.01%.
The American Society for Testing and Matertals takes no positron respecting the vahdtty of any patent rights asserted m connection with any item mentioned in this standard Users of this standard are expressly advised that determination of the validffy of any such patent rights, and the risk of infringement of such rights, are entirely their own responsiDihty. Thts standard Is subject to revision at any time by the responsible technical committee and must be reviewed every hve years and if not revtsed, etther reapproved or withdrawn. Your comments are mvtted either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments wtll recewe careful consideration at a meeting of the responstble technical committee, which you may attend If you feel that your comments have not received a raft hearing you should make your views known to the ASTM Commtttee on Standards, 100 Barr Herbor Dnve, West Conshohocken, PA 19428
899
~[~
Designation: D 5453 - 93 Standard Test Method for Determination of Total Sulfur in Light Hydrocarbons, Motor Fuels and Oils by Ultraviolet Fluorescence 1 This standard is issued under the fixed designation D 5453; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (¢) indicates an editorial change since the last revision or reapproval.
4. Significance and Use
1. Scope 1.1 This test method covers the determination of total sulfur in liquid hydrocarbons, boiling in the range from approximately 25"C to 400°C, with viscosities between approximately 0.2 and 10 cSt (mm2/S) at room temperature. This test method is applicable to naphthas, distillates, motor fuels and oils containing 1.0 to 8000 mg/kg total sulfur. 1.2 This test method is applicable for total sulfur determination in liquid hydrocarbons containing less than 0.35 % (m/m) halogen(s). 1.3 SI (Metric) units are regarded as standard. 1.4 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. See 3.2, 6.3, 6.4, 8.1 and Section 7.
4.1 Some process catalysts used in petroleum and chemical refining can be poisoned when trace amounts of sulfur bearing materials are contained in the feedstocks. This test method can be used to determine sulfur in process feeds and can also be used to control sulfur in finished products.
2. Referenced Documents
2.1 ASTM Standards: D 4057 Practice for Manual Sampling of Petroleum and Petroleum Products 2 D 4177 Practice for Automatic Sampling of Petroleum and Petroleum Products 2 3. Summary of Test Method 3.1 A hydrocarbon sample is directly injected or placed in a sample boat. The sample or boat, or both, enter into a high temperature combustion tube where the sulfur is oxidized to sulfur dioxide (SO2) in an oxygen rich atmosphere. Water produced during the sample combustion is removed and the sample combustion gases are next exposed to ultraviolet (UV) light. The SO2 absorbs the energy from the UV light and is converted to excited sulfur dioxide (SO2"). The fluorescence emitted from the excited SO2' as it returns to a stable state SO2 is detected by a photomultiplier tube and the resulting signal is a measure of the sulfur contained in the
sample. NOTE 1: Warning--Exposure to excessive quantities of ultraviolet (UV) light is injurious to health. The operator must avoid exposingany part of their person, especiallytheir eyes,not only to direct UV light but also to secondaryor scattered radiation that is present. J This test method is under the jurisdiction of ASTM Committee D-02 on Petroleum Products and Lubricants and is the direct responsibility of Subeom. mittee I:)02.030(3 on Eleetrometric Methods. Current edition approved Sept. 15, 1993. Published November 1993. 2 Annual Book of ASTM Standards, Vol 05.02.
5. Apparatus 3 5.1 Furnace--An electric furnace held at a temperature (1100"C) sufficient to pyrolyze all of the sample and oxidize sulfur to SO2. 5.2 Combustion Tube--A quartz combustion tube constructed to allow the direct injection of the sample into the heated oxidation zone of the furnace or constructed so that the inlet end of the tube is large enough to accommodate a quartz sample boat. The combustion tube must have side arms for the introduction of oxygen and carrier gas. The oxidation section shall be large enough (see Figs. 1 and 2) to ensure complete combustion of the sample, Figs. 1 and 2 depict conventional combustion tubes. Other configurations are acceptable if precision is not degraded. 5.3 Flow ControlmThe apparatus must be equipped with flow controllers capable of maintaining a constant supply of oxygen and carrier gas. 5.4 Drier Tube--The apparatus must be equipped with a mechanism for the removal of water vapor. The oxidation reaction products include water vapor which must be eliminated prior to measurement by the detector. This can be accomplished with a membrane drying tube, permeation dryer, that utilizes a selective capillary action for water removal. 5.5 V Z Fluorescence Detector--A qualitative and quantitative detector capable of measuring light emitted from the fluorescence of sulfur dioxide by UV light. 5.6 Microlitre Syringe--A microlitre syringe capable of accurately delivering 5 to 20-microlitre quantities. The needle should be 50 mm (:1:5 ram) long. 5.7 Sample Inlet System--Either of two types of sample inlet systems can be used. 5.7.1 Direct Injection--A direct injection inlet system must be capable of allowing the quantitative delivery of the material to be analyzed into an inlet carrier stream which directs the sample into the oxidation zone at a controlled an~! repeatable rate. A syringe drive mechanism which discharges the sample from the microlitre syringe at a rate of approximately 1 ~tL/s is required. See example, Fig. 3. s Apparatus manufactured in several variations by Antek Instruments, Inc., Houston, TX has been found suitable for this purpose.
900
~
D 5453 450ram
~
'. ~ "
12ram
,-n
/-
P " - " 50ram 100ram
See DETAIL BELOW
~A;,~,;,~; T M ,°
~ •
~J
~1
I~
'~'~
ID MUST FIT 12ram $EPTUM
t2rnm ~q" 25ram
BURNER TIP AND SEPTUM DETAILS
Direct Inject
FIG. 1
r
6g ~.mm
I
T M
:1
from OO x 2ram ID
6ram 00 x 2ram IO
-1111 U
6|mmO /
FIG. 2 Boat Inlet
- INLET- CARRIER/OXYGEN / ~ j ' ~ DIRECT INJECT PYROTUBE
SYRINGE
DRIVE PYRO
FIG. 3 Syringe Drive, Direct Injection 901
(~) D 5453
i/
FURNACE
~
INIET-CARRIER~"~)XYGE mNa'/~
BOATDRIVE
FIG. 4 BoatInlet System 5.7.2 Boat Inlet System--An extended combustion tube provides a seal to the inlet of the oxidation area and is swept by a cartier gas. The system provides an area to position the sample carrying mechanism (boat) at a retracted position removed from the furnace. The boat drive mechanism will fully insert the boat into the hottest section of the furnace inlet. The sample boats and combustion tube are constructed of quartz. The combustion tube provides a coolant jacket for the area in which the retracted boat rests awaiting sample introduction from a microlitre syringe. A drive mechanism which advances and withdraws the sample boat into and out of the furnace at a controlled and repeatable rate is required. See example, Fig. 4. 5.8 Refrigerated CirculatorDAn adjustable apparatus capable of delivering a coolant material at a constant temperature as low as 4"C could be required when using the boat inlet injection method (optional). 5.9 Strip Chart Recorder, (optional). 5.10 Balance with a Precision of +O.01 mg, (optional).
lessening the accuracy of the determination. 6.2 Inert Gas--Argon or helium only, high purity grade (that is, chromatography or zero grade), 99.998 % rain purity, moisture 5 ppm w/w max. 6.3 Oxygen--High purity (that is, chromatography or zero grade), 99.75 % rain purity, moisture 5 ppm w/w max, dried over molecular sieves. NOTE 2: Warning--Vigorously accelerates combustion. 6.4 Toluene, Xylenes, Isooctane, Reagent grade. (Other solvents similar to those occurring in samples to be analyzed are also acceptable.) Correction for sulfur contribution from solvents (solvent blank) used in standard preparation and sample specimen dilution is required. Alternatively, use a solvent with nondetectable sulfur contamination relative to the sample unknown makes the blank correction unnecessary. NoTE 3: Warnhag--Flammable solvents. 6.5 Dibenzothiophene, FW184.26, 17.399 % (m/m) S (Note 4). 6.6 Butyl Suede, FW146.29, 21.92 70 (m/m) S (Note 4). 6.7 Thionaphthene (Benzothiophene), FW134.20, 23.90 70 (m/m) S (Note 4). NOTE 4--A correction for chemical impurity can be required. 6.8 Quartz Wool: 6.9 Sulfur Stock Solution, 1000 gg S/mL--Prepare a stock solution by accurately weighing 0.5748 g of dibenzothiophene or 0.4652 g of Butyl Sulfide or 0.4184 g of thionaphthene into a tared 100 mL volumetric flask. Dilute to volume with selected solvent. This stock can be further diluted to desired sulfur concentration (Note 5). NOTE 5mWorking standards should be remixed on a regular basis depending upon frequency of use and age. Typically, stock solutions have a usefullife of about 3 months.
6. Reagents
6.1 Purity of ReagentsDReagent grade chemicals shall be used in tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available. 4 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without 4 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Peele, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD.
902
~ O5453 7. Hazards 7.1 High temperature is employed in this test method. Extra care must be exercised when using flammable materials near the oxidative pyrolysis furnace. 8. Sampling 8.1 Obtain a test unit in accordance with Practice D 4057 or Practice D 4177. To preserve volatile components which are in some samples, do not uncover samples any longer than necessary. Samples should be analyzed as soon as possible after taking from bulk supplies to prevent loss of sulfur or contamination due to exposure or contact with sample container. NOTE 6: Warning--Samples that are collectedat temperatures below room temperature can undergo expansion and rupture the container. For such samples, do not fill the container to the top; leavesufficientair space abovethe sample to allow room for expansion. 8.2 If the test unit is not used immediately, then thoroughly mix in its container prior to taking a test specimen. 9. Preparation of Apparatus 9.1 Assemble and leak check apparatus according to manufacturer's instructions. 9.2 Adjust the apparatus, dependent upon the method of sample introduction, to meet conditions described in Table 1. 9.3 AdJust instrument sensitivity, baseline stability and perform instrument blanking procedures following manufacturer's guidelines. 10. Calibration and Standardization 10.1 Select one of the suggested curves outlined in Table 2. Prepare a series of calibration standards by making dilutions of the stock solution to cover the range of operation and consisting of sulfur type and matrix similar to samples to be analyzed. 10.2 Flush the microlitre syringe several times with the sample prior to analysis. If bubbles are present in the liquid column, flush the syringe and withdraw a new sample. 10.3 A sample size recommended for the curve selected from Table 2 must be quantitatively measured prior to injection into the combustion tube or delivery into the sample boat for analysis (Note 6). There are two alternative techniques available. TABLE 1
TABLE 2
10.5 Calibrate the instrument using one of the following two techniques. 10.5.1 Perform measurements for the calibration standards and blank using one of the procedures described in Sections 10.2 through 10.4. Measure the calibration standards and blank three times. Subtract the average blank response from each standard measurement before determining the average integrated response (see 6.4). Construct a curve plotting average integrated detector response (y=axis) versus pg sulfur injected (x-axis). This curve should be linear and system performance must be checked with the calibration standards at least once per day. 10,5,2 If the apparatus features an internal calibration routine, measure the calibration standards and blank three
Sulfur Standards
Curve II Sulfur ng/gL.
Curve Ul Sulfur ng/p.L
0.50 2.50 5.00
5.00 25.00 50.00 100.00 Injection Size 5-10 pL
100.00 500.00 1000.00
Injection Size 10-20 pL
NOTE 8--Slowing boat speed or briefly pausing the boat in the
1 p,L/s 140-160 mm/mln 1100" + 25°C 450-500 cc/min 10-30 cc/min 130-160 cc/min
Curve I Sulfur ng/~L
10.3.2 Fill the syringe as described in 10.3.1. Weigh the device before and after injection to determine the amount of sample injected. This procedure can provide greater precision than the volume delivery method, provided a balance with a precision of +0.01 mg is used. 10.4 Once the appropriate sample size has been measured into the microlitre syringe, promptly and quantitatively deliver the sample into the apparatus. Again, there are two alternative techniques available. 10.4.1 For direct injection, carefully insert the syringe into the inlet of the combustion tube and the syringe drive. Allow time for sample residues to be burned from the needle (Needle Blank). Once a stable baseline has reestablished, promptly start the analysis. Remove syringe once the apparatus has returned to a stable baseline. 10.4.2 For the boat inlet, quantitatively discharge the contents of the syringe into the boat containing quartz wool at a slow rate being careful to displace the last drop from the syringe needle. Remove the syringe and promptly start the analysis. The instrument baseline should remain stable until the boat approaches the furnace and vaporization of the sample begins. Instrument baseline is to be restablished before the boat has been completely withdrawn from the furnace (Note 8). Once the boat has reached its fully retracted position, allow one rain for cooling before the next sample injection (Note 9). furnace can be necessaryto assure complete sample combustion. NOTe 9--The level of boat cooling r~uired and the onset of sulfur detection followingsample injection are directly related to the volatility of the materials analyzed. The use of a refrigerated circulator to minimize the vaporization of the sample until the boat begins approaching the furnace could be required.
Typical Operating Conditions
Syringe Drive (Direct Inject) Drive Rate (700-750) Boat Drive (Boat Inlet) Drive Rate (700-750) Furnace Temperature Furnace Oxygen Flowmeter Setting (3.8-4.1) Inlet Oxygen Fiowmeter Setting (0.4-0.8) Inlet Carrier Flowmeter Setting (3.4-3.6)
NOTe 6--Injection of a constant or similar sample size for all materials analyzed in a selected operating range promotes consistent combustion conditions. 10.3.1 The volumetric measurement of the injected material can be obtained by filling the syringe to the selected level. Retract the plunger so that air is aspirated and the lower liquid meniscus falls on the I0 % scale mark and record the volume of liquid in the syringe. After injection, again retract the plunger so that the lower liquid meniscus falls on the 10 % scale mark and record the volume of liquid in the syringe. The difference between the two volume readings is the volume of sample injected (Note 7). NOTE 7--An automatic sampling and injection devicecan be used in place of the describedmanual injvction procedure.
Injection Size 5 p.L
903
~
D 5453
times using one of the procedures described in Sections 10.2 through 10.4. If blank correction is required and is not available (see 6.4), calibrate the analyzer as per manufacturer's instructions using the average response for each standard versus ng of sulfur. This curve should be linear and system performance must be checked with the calibration standards at least once per day. 10.6 If analyzer calibration is performed using a different calibration curve than listed in Table 2, select an injection size based on the curve closest in concentration to the measured solution(s) (Note 10). NOTE lO--Injection of 10 gL of the 100 ng/~tL standard would establish a calibration point equal to I000 ng or 1.0 gg. 11. Procedure 11.1 Obtain a test specimen using the procedure described in Section 8. The sulfur concentration in the test specimen must be less than the concentration of the highest standard and greater than the concentration of the lowest standard used in the calibration. If required, a dilution can be performed on either a weight or volume basis. 11.1.1 Gravimetric Dilution--Record the mass of the test specimen and the total mass of the test specimen and solvent. 11.1.2 Volumetric DilutionmRecord the mass of the test specimen and the total volume of the test specimen and solvent. 11.2 Measure the response for the test specimen solution using one of the procedures described in Sections 10.2 through 10.4. 11.3 Inspect the combustion tube and other flow path components to verify complete oxidation of the test specimen. 11.3.1 Direct Inject SystemsmReduce the sample size or the rate of injection, or both, of the specimen into the furnace if coke or sooting is observed. 11.3.2 Boat Inlet Systems--Increase the residence time for the boat in the furnace if coke or soot is observed on the boat. Decrease the boat drive introduction rate or specimen sample size, or both, if coke or soot is observed on the exit end of the combustion tube.
11.3.3 Cleaning and Recalibration--Clean any coked or sooted parts per manufacturer's instructions. After any cleaning or adjustment, assemble and leak check the apparatus. Repeat instrument calibration prior to reanalysis ofthe test specimen. 11.4 Measure each test specimen solution three times and calculate the average detector responses.
( I - Y)
SxMxK,
(3)
G Sulfur, ppm ~tg/g) - V x D × g/1000 mg
(4)
or,
where: D ffi density of test specimen solution, mg/p.L (neat injection), or concentration of solution, mg/p.L (volumetric dilute injection), Ks = gravimetric dilution factor, mass of test specimen/mass of test specimen and solvent, g/g, M = mass of test specimen solution injected, either measured directly or calculated from measured volume injected and density, V × D, mg, V ffi volume of test specimen solution injected, either measured directly or calculated from measured mass injected and density, M/D, ttL, G -- sulfur found in test specimen, ~tg.
13.1 Repeatability--The difference between two test resuits obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following values in only I ease in 20, where x ffi the average of the two test results. r - 0.1867(x) (°.6~)
(I)
or, (I- Y) Sulfur,ppm (~tg/g)= S x v x Kv
O Sulfur, ppm (ttg/g) - M × Ks × g/1000 mg
13. Precision
12. Calculation 12.1 For analyzers calibrated using a standard curve, calculate the sulfur content of the test specimen in parts per million (ppm) as follows: Sulfur, ppm (~tg/g)=
where: D ffi density of test specimen solution, g/mL, I = average of integrated detector response for test specimen solution, counts, Ks-- gravimetrie dilution factor, mass of test specimen/mass of test specimen and solvent, g/g, Kv= volumetric dilution factor, mass of test specimen/ volume of test specimen and solvent, g/mL, M = mass of test specimen solution injected, either measured directly or calculated from measured volume injected and density, V x D, g, S ffi slope of standard curve, counts/gg S, V -- volume of test specimen solution injected, either measured directly or calculated from measured mass injected and density, M/D, ttL, and Y = y-intercept of standard curve, counts. 12.2 For analyzers calibrated using internal calibration routine without blank correction, calculate the sulfur of the test specimen in parts per million (ppm) as follows:
(2)
(5)
13.2 ReproduciblTity--The difference between two single and independent results obtained by different operators working in different laboratories on identical test material would, in the long run, in the normal and correct operation ofthe test method, exceed the following values in only I case in 20, where x ffi the average of the two test results, R .. 0.2217(x)t°.92) (6) 13.3 Bias--The bias of this method was determined in a
904
~1~ D 5453 on the SRMs were within the repeatability of the test method. 13.4 Examples of the above precision estimates for selected absolute values of x are set out in Table 3.
1992 research report, 5 by analysis of standard reference materials (SRMs) containing known levels of sulfur in hydrocarbon. This report indicated that the results obtained
14. Keywords 14.1 fluorescence; sulfur; ultraviolet
5 Supporting data available from ASTM Headquarters. Request RR:D02-1307.
TABLE 3 Concentration (mg/kg S) 1 5 10 50 1 O0 500 1000 5000
Repeatability (r) and Reproducibility (R) ~,
r
R
0.187 0.515 0.796 2.195 3.397 9.364 14.492 39.948
0.222 0.975 1.844 8.106 15,338 07,425 127,575 560,813
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users el this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reepproved or withdrawn. Your comments are Invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at e meeting of the reSponsible technical committee, which you may attend. If you feel that your comments have not received e fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
905
(~l~ Designation: D 5454 - 93 Standard Test Method for Water Vapor Content of Gaseous Fuels Using Electronic Moisture Analyzers 1 This standard is issued under the fixed designation D 5454; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (4) indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 This test method covers the determination of the water vapor content of gaseous fuels by the use of electronic moisture analyzers. Such analyzers commonly use sensing cells based on phosphorus pentoxide, P205, aluminum oxide, A1203, or silicon sensors. 1.2 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate sofety and health practices and determine the applicability of regulatory limitations prior to use.
3.1.4 water dewpoint--the temperature (at a specified pressure) at which liquid water will start to condense from the water vapor present. Charts of dewpoints versus pressure and water content are found in Test Method D 1142.
4. Significance and Use 4.1 Water content in fuel gas is the major factor influencing internal corrosion. Hydrates, a semisolid combination of hydrocarbons and water, will form under the proper conditions causing serious operating problems. Fuel heating value is reduced by water concentration. Water concentration levels are therefore frequently measured in natural gas systems. A common pipeline specification is 4 to 7 lb/ MMSCF. This test method describes measurement of water vapor content with direct readout electronic instrumentation.
2. Referenced Documents
2.1 A S T M Standards: D 1142 Test Method for Water Vapor Content of Gaseous Fuels by Measurements of Dew-Point Temperature 2 D 1145 Method of Sampling Natural Gas 3 D 4178 Practice for Calibrating Moisture Analyzers4 D4888 Test Method for Water Vapor In Natural Gas Using Length-of-Stain Detector Tubes 2 3. Terminology 3.1 Description of Terms Specific to This Standard: 3.1.1 capacitance type cell--this cell uses aluminum coated with AI203 as part of a capacitor. The dielectric AI20 a film changes the capacity of the capacitor in relation to the water vapor present. Unlike P205 cells, this type is nonlinear in its response. If silicon is used instead of aluminum, the silicon cell gives improved stability and very rapid response. 3.1.2 electrolytic type cellmthis cell is composed of two noble metal electrode wires coated with P205. A bias voltage is applied to the electrodes, and water vapor chemically reacts, generating a current between the electrodes proportional to the water vapor present. 3.1.3 water content--water content is customarily expressed in terms of dewpoint, OF or °C, at atmospheric pressure, or the nonmetric term of pounds per million standard cubic feet, Ib/MMSCF. The latter term will be used in this test method because it is the usual readout unit for electronic analyzers. One Ib/MMSCF = 2 I. 1 ppm by volume or 16.1 mgm/m 3 of water vapor. Analyzers must cover the range 0.1 to 50 Ib/MMSCF.
5. Apparatus 5.1 The moisture analyzer and sampling system will have the following general specifications: 5.1.1 Sampling SystemmMost errors involved with moisture analysis can be eliminated with a proper sampling system. 5.1.1.1 A pipeline sample should be obtained with a probe per Method D 1145. The sample temperature must be maintained 2°C (3OF) above the dewpoint of the gas to prevent condensation in the sample line or analyzer. Use of insulation or heat tracing is recommended at cold ambient temperatures. 5.1.1.2 Analyzer sensors are very sensitive to contamination. Any contaminants injurious to the sensor must be removed from the sample stream prior to reaching the sensor. This must be done with minimum impact on accuracy or time of response. If the contaminant is an aerosol of oil, glycol, etc., a coalescing filter or semipermeable membrane separator must be used. 5.1.2 ConstructionmSampling may be done at high or low pressure. All components subject to high pressure must be rated accordingly. To minimize diffusion and absorption, all materials in contact with the sample before the sensor must be made of stainless steel. Tubing of I/8 in. stainless steel is recommended. NOTE h P r e c a u t i o n - - U s e appropriate safety precautions when sampling at high pressure.
i This test method is under the jurisdiction of ASTM Committee D-3 on Gaseous Fuels and is the direct responsibility of Subcommittee D03.05 on Determination of Special Constituents of Gaseous Fuels. Current edition approved Sept. 15, 1993. Published November 1993. 2 Annual Book of ASTM Standards, Vol 05.05. 3 Discontinued--See 1986 Annual Book of ASTM Standards, Vol 05.05. 4 Annual Book of ASTM Standards, Vol 05.02.
5.1.2.1 Pressure gages with bourdon tubes should be avoided due to water accumulation in the stagnant volume. 5.1.2.2 Sample purging is important to satisfactory response time. There must be a method to purge the sample line and sample cleanup system. 906
~
O 5454
BACK PRESSURE
C.~AS IN LE'r
SHUTOFF
~.
J
AN.aJ,.Y~,JER )
i
HIGH PRF..~$URE
ICEANATERMIXTURE32"F
N__
•
Flow Diagram FIG. 1 Moisture Calibrator
5.1.3 ElectronicsmOutput from the sensor will be linearized for analog or digital display in desired units (usually Ib/MMSCF). There must be an adjustment for calibration accuracy available that can be used in the field if a suitable standard is available. (This does not apply to instruments that assume complete chemical reaction of water. Their accuracy still must be verified as in Section 6.) 5.1.4 Power Supply--Analyzers for field use will have rechargeable or easily replaceable batteries.
established by tube weight loss. 6.4 Compressed gas water vapor standards may be used, provided they are checked by an independent method once a month. 6.5 Calibrate the analyzer using one of the standards in 6.3 and 6.4 and respective procedures. Calibration must be at two points, one higher and one lower than average expected readings. Some analyzers can have large nonlinear errors. Use the calibration adjustment if applicable.
NOTE 2: Caution~Analyzersfor use in hazardouslocationsbecause of combustible gas must be certified as meeting the appropriate
7. Procedure
7.1 Preparation--The analyzer operation and calibration should be checked according to the manufacturer's recommendations prior to use. See Section 6. Verification of a dry instrument using dry compressed nitrogen to get a reading below 1 Ib/MMSCF is recommended prior to field use. 7.2 Sample Procedure--Sample as in paragraph 5.1.1.1. Use as short a sample line as practical. Purge the sample for 2 min before valving to the sensor. 7.3 Reading--The time for a sensor to come to equilibrium is variable depending on its type and condition. The analyzer may require 20 rain to stabilize. Some analyzers have an external recorder output, and these can be used with a chart recorder to become familiar with the true equilibrium response time.
requirements. 6. Calibration 6.1 A calibration technique is described in Practice D 4178 that should be used to verify the accuracy of the analyzer. This method uses the known vapor pressure of water at 0°C and mixes wet gas and dry gas to make up the total pressure so that a standard gas of known water concentration is achieved. 6.1.1 Instruments very sensitive to sample flow must be compensated for barometric pressure. 6.2 A commercially made water vapor calibrator is shown in Fig. 1, which uses essentially the same technique. This method is useful only between 5 to 50 Ib/MMSCF. 6.3 Low range water vapor standards may be obtained by the use of water permeation tubes. Permeation rates must be
8. Precision and Bias 8.1 Precision data is being prepared for this test method
by an interlaboratorystudy.
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility.' This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reepproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responaibie technical committee, which you may attend, if you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
907
~)
Designation:D 5482 - 96 Standard Test Method for Vapor Pressure of Petroleum Products (Mini Method-Atmospheric) 1 This standard is issued under the fixed designation D 5482; the number immedialely following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (0 indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 This test method provides a procedure for the determination of total vapor pressure of petroleum products using automatic vapor pressure instruments. The test method is suitable for testing samples with boiling points above 0*C (32*F) that exert a vapor pressure between 7 and 110 kPa (1.0 and 16 psi) at 37.8*C (100*F) at a vapor-to-liquid ratio of 4:1. The test method is applicable to gasolines containing oxygenates. No account is made of dissolved water in the sample.
D 5190 Test Method for Vapor Pressure of Petroleum Products (Automatic Method)a D 5191 Test Method for Vapor Pressure of Petroleum Products (Mini Method) a 3. Terminology 3.1 Definitions of Terms Specific to This Standard: 3.1.1 dry vapor pressure equivalent (DVPE)--a value calculated by a correlation equation (see 13.2) from the total pressure, 3. I. I. l Discussion--The DVPE is expected to be equivalent to the value obtained on the sample by Test Method D 4953. 3.1.2 total pressure--the observed pressure measured in the experiment that is the resultant pressure increase from the initial ambient atmospheric pressure.
NOTE l - - B e c a u s e the external atmospheric pressure does not influence the resultant vapor pressure, this vapor pressure is an absolute pressure at 37.8°C (100"F) in kPa (psi). This vapor pressure differs from the true vapor pressure o f the sample due to some small vaporization o f the sample and dissolved air into the air o f the confined space.
1.2 This test method is a modification of Test Method D 5191 (Mini Method) where the test chamber is at atmospheric pressure prior to sample injection. 1.3 This test method covers the use of automated vapor pressure instruments that perform measurements on liquid sample sizes in the range from 1 to 10 mL. 1.4 This test method is suitable for the determination of the dry vapor pressure equivalent (DVPE) of gasoline and gasoline-oxygenate blends by means of a correlation equation (see 13.2). The calculated DVPE is considered equivalent to the result obtained on the same material when tested by Test Method D 4953. 1.5 The values stated in acceptable SI units are regarded as standard. The values given in parentheses are provided for information only. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. (For specific hazard statements, see Note 3.)
4. Summary of Test Method 4.1 A known volume of chilled, air-saturated sample is introduced into a thermostatically controlled test chamber, the internal volume of which is five times that of the total test specimen introduced into the chamber. The test chamber is at atmospheric pressure prior to introduction of the sample. After introduction of the sample into the test chamber the test specimen is allowed to reach thermal equilibrium at the test temperature, 37.8°C (100*F). The resulting rise in pressure in the chamber is measured using a pressure transducer sensor and indicator. 4.2 The measured total vapor pressure is converted to a dry vapor pressure equivalent (DVPE) by use of a correlation equation (see 13.2). 5. Significance and Use 5.1 Vapor pressure is an important physical property of volatile liquids. 5.2 Vapor pressure is critically important for both automotive and aviation gasolines, affecting starting, warm-up, and tendency to vapor lock with high operating temperatures or high altitudes. Maximum vapor pressure limits for gasoline are legally mandated in some areas as a measure of air pollution control.
2. Referenced Documents 2.1 A S T M Standards: D4057 Practice for Manual Sampling of Petroleum and Petroleum Products2 D4953 Test Method for Vapor Pressure of Gasoline and Gasoline-Oxygenate Blends (Dry Method)3
6. Apparatus 6.1 Vapor Pressure Apparatus--The type of apparatus4 suitable for use in this test method employs a small volume
t This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum products and Lubricants and is the direct responsibility of Subcommittee 1302.08.O1) on RVP and V/L Ratio. Current edition approved June 10, 1996. Published August 1996. Originally published as D 5482 - 93. Last previous edition D 5482 - 93. 2 Annual Book of ASTM Standards, Vo105.02. 3 Annual Book of ASTM Standards, Vol 05.03.
4 The following instruments have been found satisfactory for use in this test procedure as determined by interlaboratory testing: Herzog Mini Reid Vapor PrematureModel MP970--available from Walter Herzog OmbH, Lauda, Germany and UIC, Inc., Joliet, IL, and ABB Model 4100---avalisble from ABB Process Analyti~ Lewisburg, WV.
908
i ~ D 5482 test chamber incorporating a transducer for pressure measurements and associated equipment for thermostatically controlling the chamber temperature. 6.1.1 The test chamber shall be designed to contain between 2 and 50 mL of liquid and vapor and be capable of maintaining a vapor-liquid ratio between 3.95 to 1.00 and 4.05 to 1.00. 6.1.2 The pressure transducer shall have a minimum operational range from 0 to 172 kPa (0 to 25.0 psi) with a minimum resolution of 0.1 kPa (0.01 psi) and a minimum accuracy of :1:0.3 kPa (±0.05 psi). The pressure measurement system shall include associated electronics and readout devices to display the resulting pressure reading. 6.1.3 A thermostatically controlled heater shall be used to maintain the test chamber at 37.8 ± 0.1*C (100 + 0.2*F) for the duration of the test. 6.1.4 A platinum resistance thermometer shall be used for measuring the temperature of the test chamber. The minimum temperature range of the measuring device shall be from ambient to 75°C (167*F) with a resolution of 0.1*C (0.2*F) and accuracy of 0. I*C (0.2*F). 6.1.5 The vapor pressure apparatus shall have provisions for introduction of the test specimen into the test chamber and for the cleaning or purging of the chamber following the test. 6.2 Syringe, if required, gas fight, 1 to 20 mL capacity with a ± 1 % or better accuracy and a + 1 % or better precision. The capacity of the syringe shall not exceed two times the volume of the test specimen being dispensed, and shall be chosen so as to provide maximum accuracy and resolution for the volume to be injected. 6.3 Iced-Water Bath or Air Bath, for chilling the Samples and syringe to temperatures between 0 and I*C (32 to 34"F). 6.4 Mercury Manometer, for calibration of the pressure transducer, shall include the range from 0 to 130 kPa (0 to 19 psi). The manometer scale shall be graduated in increments of 0.2 kPa (0.03 psi), nominally. 6.5 Pressure Source, clean, dry compressed gas or other suitable compressed air capable of providing pressure for calibration of the transducer and cleaning of the cell.
7.4 7.5 7.6 7.7
2,2.Dimethylbutane (Warning--See Note 3.) "2,3-Dimethylbutane (Warning--See Note 3.) 2.Methylpentane (Warning--See Note 3.) Toluene (Warning--See Note 3.)
NOTE 3:
Warning--~clohexane,
toluene,
cyclopentane,
2,2-
dimethylbutane, 2,3-dimethylbutane and 3-methylpentane are flammable and a health hazard. 8. Sampling 8.1 GeneralRequirements: 8.1.1 The extreme sensitivity of vapor pressure measurements to losses through evaporation and the resulting changes in composition is such as to require the utmost precaution and the most meticulous care in the handling of samples.
8.1.2 Obtain a sample and test specimen in accordance with 10.3 of Practice D 4057, except do not use 10.3.1.8 of Practice D 4057, Sampling by Water Displacement, for fuels containing oxygenates. Use a I-L (l-qt) sized container Idled between 70 to 80 % with sample. 8.1.3 Perform the vapor pressure determination on the first test specimen withdrawn from a sample container. Do not use the remaining sample in the container for a second vapor pressure determination. If a second determination is necessary, obtain a new Sample. 8.1.4 Protect samples from excessive temperatures prior to testing. This can be accomplished by storage in an appropriate ice bath or refrigerator. 8.1.5 Do not test Samples stored in leaky containers. Discard and obtain a new sample if leaks are detected. 8.1.6 Do not store Samples in plastic (polyethylene, polypropylene, etc.) containers, since volatile materials may diffuse through the walls of the container. 8.2 Sampling Temperature--Cool the sample container and contents in an ice bath or refrigerator to the 0 to I°C (32 to 34*F) range prior to opening the sample container. Allow sufficient time to reach this temperature. Verify the sample temperature by direct measurement of the temperature of a similar liquid in a similar container placed in the cooling bath or refrigerator at the same time as the Sample. 8.3 Verification of Sample Container Filling--After the sample reaches thermal equilibrium at 0 to I oc, take the container from the cooling bath or refrigerator, wipe dry with an absorbent material and unseal. Using a suitable gage, confirm that the sample volume equals 70 to 80 volume % of the container capacity. 8.3.1 Do not perform a vapor pressure test on the sample if the container is filled to less than 70 volume % of the container capacity. 8.3.2 If the container is more than 80 volume % full, pour out enough Sample to bring the container contents within the 70 to 80 volume % range. Do not return any sample to the container once it has been withdrawn. 8.4 Air Saturation of Sample in Sample Container: 8.4.1 With the sample again at a temperature of 0 to l'C, take the container from the cooling bath or refrigerator, wipe it dry with an absorbent material, unseal it momentarily, taking care that no water enters, reseal and shake it vigorously. Return it to the bath or refrigerator for a minimum of 2 rain. 8.4.2 Repeat 8.4.1 twice more. Return the Sample to the
N o t e 2 - - A vacuum source is an alternate means for cleaning of the cell.
7. Reagents and Materials
7.1 Purity of Reagents--Use chemicals of at least 99 % purity for quality control checks (Section 11). Unless otherwise indicated, it is intended that all reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where such specifications are available? Lower purities can be used, provided it is fast ascertained that the reagent is of sufficient purity to permit its use without lessening the accuracy of the determination. 7.2 Cyclohexane (Warning--See Note 3.) 7.3 Cyclopentane(Warning--See Note 3.) 5 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DE. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), RockviUe, MD.
909
¢ ~ D 5482 bath or refrigerator until the beginning of the procedure. 8.5 Verification of Single Phase--After drawing a test specimen and injecting it into the instrument for analysis, check the remaining sample for phase separation. When the sample is contained in a @ass container, this observation can be made prior to sample transfer. When the sample is contained in a non-transparent container, mix the sample thoroughly and immediately pour a portion of the remaining sample into a glass container and observe for evidence of phase separation. When the sample is not clear and bright or when a second phase is observed, discard the test and the sample.
vapor pressures, as found in A S T M DS4B, 6 include: cyclopentane, 68.3 Ida (9.91 psi);2,2-dimethylbutane, 68.0 kPa (9.86 psi); 2,3-dimethylbutane, 51.1 kPa (7.41 psi); 2-methylpentane, 46.7 kPa (6.77 psi);cyclohexane, 22.5 kPa (3.26 psi);and toluene, 7.1 kPa (I.03 psi).v NOTE 4 ~ I t iS recommended that at least one type of control sample used in I0.I be representative of the samples regularly tested by the laboratory. The total vapor pressure measurement process (including operator technique) can be checked periodically by performing this test
method on previouslyprepared samples from one batch of product, in accordance with the procedure described in 8.1.2. Samples should be stored in an environment suitable for long term storage without sample degradation. Analysisof resultsfrom these quality controlsamplescan be carriedout using control chart techniquess or other statistically equivalent techniques.
9. Preparation of Apparatus 9.1 Prepare the instrument for operation in accordance with the manufacturer's instructions. 9.2 Prepare the sample introduction accessories, if required, according to the manufacturer's instructions. 9.3 Chill the sample syringe to between 0 and 4.5°C (32 and 40*F) in a refrigerator or ice bath. Avoid water contamination of the syringe reservoir by suitably sealing the outlet of the syringe during the cooling process. 9.4 Clean and dry the test chamber according to the manufacturer's instructions. With the test chamber sealed observe that the instrument display is stable and does not exceed 0.00 + 0.20 Ida (0.00 + 0.03 psi). 9.5 If in doubt of the cleanliness of the cell, refer to the cleaning procedure in the manufacturer's instructions, or if the display does not return to zero, refer to the calibration procedure in the manufacturer's instructions. 9.6 Verify that the temperature of the test chamber is within the required range from 37.8 + 0.1°C (100 + 0.2"F). 10. Calibration 10.1 Pressure Transducer: 10.1.1 Cheek the calibration of the transducer according to the manufacturer's instructions on a monthly basis or when needed as indicated from the quality control checks (Section 1 I). The calibration of the transducer shall be checked using two reference points, ambient barometric pressure, and a pressure above ambient pressure, determined by the operator, which is at least 80 % of the expected maximum pressure encountered during the test. I0.1.2 The above ambient pressure shall be measured by a mercury manometer with a scale resolution of at least 0.20 Ida (0.03 psi). 10.2 TemperatureMeasuring Device---Checkthe calibration of the temperature measuring device used to monitor the temperature of the test chamber at least every six months against a thermometer traceable to a national standard.
12. Procedure 12.1 Remove the sample from the cooling bath or refrigerator, dry the exterior of the container with absorbent material, uncap, and insert a chilled syringe. Draw a bubblefree aliquot of sample into the gas tight syringe and deliver this test specimen to the test chamber as rapidly as possible. The total time between opening the chilled sample container and securing the syringe into the test chamber shall not exceed 1 min. 12.2 Follow the manufacturer's instructions for injection of the test specimen into the test chamber, and for operation of the instrument to obtain a vapor pressure result for the test specimen. 12.3 If the instrument is capable of calculating the dry vapor pressure equivalent automatically, ensure that the equation in 13.2 is used. 13. Calculation 13.1 Record the vapor pressure reading from the instrument to the nearest 0.1 kPa (0.01 psi). For instruments that do not automatically record a stable pressure value, manually record the pressure indicator reading every minute to the nearest 0.1 kPa. When three successive readings agree to within 0.1 kPa, record the result to the nearest 0.1 Ida (0.01
psi).
13.2 Calculate the dry vapor pressure equivalent (DVPE) using Eq. 1. Ensure that the instrument reading used in this equation corresponds to the total pressure and has not been corrected by an automatically programmed correction factor. Use the variable pertaining to the type of equipment utilized.
DVPE, kPa (psi) = (0.965 X) + A
(1)
where: X ffi measured total vapor pressure in Ida (psi), A ffi 0.538 Ida (0.078 psi) for HERZOG Model SC 970, and A ffi 1.937 I d a (0.281 psi) for ABB Model 4100. NOTe 5--The correlation equationswerederived from data obtained in a 1991 interlaboratory cooperative test program? The equations
11. Quality Control Checks 11.1 Check the performance of the instrument each day it is in use by running a quality control sample consisting of a pure solvent of known vapor pressure similar to the vapor pressure of the samples to be tested. Treat the quality control check sample in the same manner as a sample. If the observed vapor pressure differs from the reference value by more than 1.0 I d a (0.15 psi), then check the instrument calibration (Section 9). 11.2 Some possible materials and their corresponding
e "Ph~ical Constants of H y d r o g e n and Non-Hydrocarbon Materials," availablefrom ASTM Headquarters. Order PCN 28-003092-12. 7 "Manual on Presentation of Data and Control Chart Analyd&"ASTM MNL 7, Sixth Edition, 1990, Section 3. e The vapor pressure values cited were obtained from Ph//lJps Pctroleum Company, Bartlesville, Oklahoma or the Table of Phys/cal Constan~ Gas Processors Association--Stsndard 2145.
910
~
D 5482
correct for the relative bias between the measured vapor pressure and the dry vapor pressure obtained in accordance with Test Method D 4953, Procedure A.
material would, in the long run, exceed the following value only in one case in twenty: 2.69 kPa (0.39 psi) for HERZOG Model SC 970 4.14 kPa (0.60 psi) for ABB Model 4100
13.3 The calculation described in Eq. l can be accomplished automatically by the instrument, if so equipped, and in such cases the user shall not apply any further correction.
15.2 Bias--Since there is no accepted reference material suitable for determining the bias for the procedures, bias cannot be determined. 15.3 Relative Bias--Statistically significant relative biases were observed in the 1991 intedaboratory cooperative test program s between the total pressure obtained using instruments described in this test method and the dry vapor pressure obtained using Test Method D 4953, Procedure A. These biases are corrected by applying Eq. 1. NOTE 7--The bias and precision information provided for the ABB apparatus are applicable only for the instruments manual mode of operation, for a nominal vapor pressure range of 13.8 to 82.68 Ida (2 to 12 psi). 15.4 Reproducibility Between Methods: NOTE 8uJust as the reproducibility supplies a 95 % confidence level on the difference between measurements by two different laboratories using the same method, there exists an equivalent reproducibility describing the 95 % confidence level on the difference between measurements by two laboratories using different methods. 15.4.1 A statistically based method for calculation of reproducibility between different methods was developed as listed below:
14. Report 14.1 Report the following information: 14.1.1 Report the dry vapor pressure equivalent to the nearest 0.1 kPa (0.01 psi) without reference to temperature.
15. Precision and Bias 15.1 The precision of this procedure as determined by the statistical examination of interlaboratory test results is as follows: NOTE 6--The following precision data were developed in a 1991
interlaboratory cooperative test program.9 Participants analyzed sample sets comprised of blind duplicates of 14 types of hydrocarbons and hydrocarbon-oxygenate blends. The oxygenates used were ethanol and MTBE. The oxygenate content ranged nominally from 0 to 15 % by volume and the vapor pressure ranged nominally from 14 to 100 Ida (2 to 15 psi). A total of 60 laboratories participated. Some participants performed more than one test method, using separate sample sets for each. Thirteen sample sets were tested by this test method using two different instruments, 26 sample sets were tested by Test Method D 4953, 13 by Test Method D 5190 and 27 by Test Method D 5191. In addition, six sets were tested by modified Test Method D 5190.
15.1.1 Repeatability--The difference between successive test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method exceed the following value only in one case in twenty: 1.31 kPa (0.19 psi) for HERZOG Model SC 970 1.79 kPa (0.26 psi) for ABB Model 4100
where: Rz, R2 = the reproducibility figures for each method under consideration, methods one and two, respectively, and n,, n2 = the number of labs whose data was used to calculate RI and R2, methods one and two, respectively. For this test method the number of labs is six.
15.1.2 Reproducibility.--The difference between two single and independent test results obtained by different operators working in different laboratories on identical test
16. Keywords
9The results of this test program are filed at ASTM H~quarters. Request
RR:D02-1286.
16.1 dry vapor pressure equivalent; gasoline; hydrocarbon-oxygenate blends; Mini Method-Atmospheric; petroleum products; vapor pressure
The American Society for Testing and Materials takes no position respecting the vaildlty of any patent rights ~ a r t e d In connection with any item mentioned In this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, end the risk of infringement of such rights, are entirely their own responsibility. This atandard is subject to revision at any time by the responsible technical ¢~rnmlttee and must be reviewed every five years and If not revised, either rsepproved or withdrawn. Yourcomments are Invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responalble technical committee, which you may attend, ff you feel that your comments have not reoaived e fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Dr/ve,WestConshohockan, PA 19428.
911
q~]~
Designation: D 5 5 0 3 - 9 4
Standard Practice for, Natural Gas Sample-Handling and Conditioning Systems for Pipeline Instrumentation 1 This standard is issuedunderthe fixeddesignationD 5503;the numberimmediatelyfollowingthe designationindicatesthe yearof originaladoptionor, in the caseof revision,the yearof last revision.A numberin parenthesesindicatesthe yearof last reapproval.A superscriptepsilon(~) indicatesan editorialchangesincethe last revisionor reapproval.
1. Scope l.l This practice covers sample-handling and conditioning systems for typical pipeline monitoring instrumentation (gas chromatographs, moisture analyzers, etc.). The selection of the sample-handling and conditioning system depends upon the operating conditions and stream composition. 1.2 This practice is intended for single phase mixtures that vary in composition. A representative sample cannot be obtained from a two phase stream. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility t f the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 1.4 The values stated in SI units are to be regarded as standard. The values stated in English units are for information only. . Referenced Documents
2.1 A S T M Standards: D 1142 Test Method for Water Vapor Content of Gaseous Fuels by Measurement of Dew-Point Temperature 2 D3764 Practice for Validation of Process Stream Analyzers 3 2.2 Other Documents: ANSI/API 2530 (AGA Report Number 3)4 AGA Report Number 85 NACE Standard MR-01-756 3. Terminology 3.1 Definitions: 3. I. 1 compressed natural gas--natural gas compressed to approximately 3600 psi. 3.1.2 density--mass per unit volume of the substance being considered. 3.1.3 dew point--the temperature and pressure at which the first droplet of liquid forms from a vapor. This practiceis underthe jurisdictionof ASTMCommitteeD-3 on Gaseous Fuelsand is the direct responsibilityof SubcommitteeD03.01 on Collectionand Measurementof GaseousSamples. CurrenteditionapprovedFeb. 15, 1994.PublishedApril 1994. 2AnnualBook ofASTM Standards, Vol 05.05. 3AnnualBookof ASTM Standards, Vol 05.02. 4AvailablefromAmericanNationalStandardsInstitute, 11 W. 42ndSt., 13th Floor,NewYork,NY 10036. ~Available from American Gas Association, 1515 Wilson Boulevard, Arlington,Virginia22209. 6Availablefrom National Associationof CorrosionEngineers, 1440-TSouth CreekDrive,Houston,Texas77084. 912
3.1.4 lag time--time required to transport the sample to the analyzer. 3.1.5 natural gas--mixture of low molecular weight hydrocarbons obtained from petroleum-bearing regions. 3.1.6 sample probe--device to extract a representative sample from the pipeline. 3. 1.7 system turnaround t i m e n t h e time required to transport the sample to the analyzer and to measure the desired components. 4. Significance and Use 4.1 A well-designed sample-handling and conditioning system is essential to the accuracy and reliability of pipeline instruments: Approximately 70 % of the problems encountered are associated with the sampling system. 5. Selection of Sample-Handling and Conditioning System 5.1 The sample-handling and conditioning system must extract a representative sample from a flowing pipeline, transport the sample to the analyzer, condition the sample to be compatible with the analyzer, switch sample streams and calibration gases, transport excess sample to recovery (or disposal), and resist corrosion by the sample. 5.2 The sample probe should be located in a flowing pipeline where the flow is fully developed (little turbulence) and where the composition is representative. In areas of high turbulence, the contaminates that normally flow along the bottom or the wall of the pipeline will form aerosols. 5.3 The purpose of the sample probe is to extract a representative sample by obtaining it near the center of the pipeline where changes in stream codaposition can be quickly detected. 5.3.1 The tip in the sample probe should be positioned in the center one third of the pipeline away from the pipeline wall where large particles accumulate. 5.3.2 The probe should be a minimum of five pipe diameters from any device that could produce aerosols or significant pressure drop. 5.3.3 The sample probe should not be located within a defined meter tube region (see ANSI/API 2530 AGA Report Number 3 and AGA Report Number 8 for more information). 5.3.4 The sample probe should be mounted vertically from the top on horizontal pipelines. The sample probe should not be located on vertical pipelines. 5.4 The sampling-handling system must transport the sample to the analyzer and dispose of excess sample. Since the sampling point and the analyzer may be separated by some distance, the time required to transport the sample to
~
D 5503
the analyzer can contribute significantly to the system turnaround time. 5.4.1 The analyzer should be located as close to the sampling point as is practical to minimize the sample lag time. 5.4.2 The sample-handling system should be equipped with a full open ball valve and a particular filter. 5.5 The sizing of the sample transport line will be influenced by a number of factors: 5.5. l The sample point pressure and the location of the pressure reduction regulator. 5.5.2 The acceptable lag time between the sample point and the analyzer. 5.5.3 The requirements of the analyzer such as flow rate, pressure, and temperature for the analysis. For multi-stream systems, the sample line and associated manifold tubing should be flushed with sufficient sample to assure a representative sample of the selected stream. 5.5.4 The presence of sample-conditioning elements will contribute to the lag time and must be considered in the calculation of the minimum sample flow rate. 5.5.4. l Each element could be considered as an equivalent length of sample line and added to the length of line from the sample point to the analyzer. 5.5.4.2 The purge time of each element is calculated as the time necessary for five volumes of sample to flow through the element. 5.5.5 A vapor sample must be kept at least 10*C above the hydrocarbon dew point temperature to prevent condensation of the sample. The sample line should be heat traced and insulated when appropriate. 5.5.5.1 For compressed natural gas (CNG) the pressure must be reduced in two stages to avoid condensation of liquids due to the Joule-Thompson effect. In a heated zone at approximately 50"C, the pressure should be dropped to approximately 10 MPa (1500 psig) and then to a suitable pressure for the analyzer. Any conditioning of the sample must be completed in the heated zone. 5.5.5.2 The sample line from the heated zone to the analyzer must be heat traced to avoid partial condensation of the sample.
METAL GASKET
OUT
IN
FILH
IN --'--~- ~ _
f,' ELEMENI
-
L-TAPERED BORE
~-- OUT
-
FILTER ELEMENT
FIG. 1 CrossSection of Common In-Line Filters
passes through a bypass filter while a majority of the sample passes across its surface, keeping it clean. The active filter element is either a disposable cartridge or a reusable sintered metal element. (See Fig. 2.) 6.1.2.3 Cyclone Filler--The cyclone filter is a centrifugal cleanup device. The sample enters at high velocity tangentially to the wall of a cylindrical-shaped vessel with a conical-shaped bottom. The centrifugal force developed by the spinning action of the gas as it follows the shape of the vessel forces particles and droplets to the wall where they are removed through the vent flow. (See Fig. 3.) 6.1.2.4 Coalescing Filter--Coalescers, also known as membrane separators, are used to force finely divided liquid droplets to combine into larger droplets so they can be separated by gravity. The design of the coalescer body forces the heavier phase out the bottom and the lighter phase out the top. The flow rates out the top and the bottom are critical for proper operation. (See Fig. 4.) (a) Since this process removes part of the sample, the impact on sample composition must be considered. (b) The coalescer should be located immediately upstream from the analyzer. 6.1.3 The combination condenser/separator is used to remove condensable liquids from a vapor sample. The sample enters the separator and cools as it passes through the
6. Apparatus 6.1 The following are common components of a samplehandling and conditioning system (see Refs (1) and ( 2 ) 7 for more information). 6.1.1 Ball valves, needle valves, and solenoid valves are typically used for stream switching, sample shutoff, calibration gas introduction, or sample vent and by-pass systems. 6.1.2 Most pipeline samples require some filtering. Since all filter elements eventually plug, they should be replaced on a regular maintenance schedule. There are several types of filter designs. 6.1.2. l In-line Filter--All of the sample passes through an in-line filter. The active filter elements are available in teflon polypropylene, co-polymer, or stainless steel. (See Fig. l.) 6. 1.2.2 Bypass Filter--Only a small portion of the sample
RLIERED Waif ~ IN~T
t
1
r~r n.ow CARI'RIOG([nLTgl S E~ A L S [U[MENT F~LTERED~
BOWL,ML'TAL.(;LASS ORPLASTIC
r~
~ INLEt
r~ow
FILTERED S~PL£ OUT
7 The boldface numbers in parentheses refer to the list of references at the end of this practice.
ELEM~NT'NHE IR FILER ED
SImEREDFILTER ELEMENT
FIG. 2 Cioss Section of Common By-Pass Filters
913
(1~ D 5503 VAPOR SAMPLE OUTLET
CLEAN SAMPLE ~,AMPLE INLET
~
SECONDARYSPIRAL OF CLEAN GAS MOVES UP AND OUT OF TOP
SAMPLE ENTERS TANGENTIALLY
COOLING INLET
ROTATIONDEVELOPS
C
~]
COOLINGOUTLET
HIGH CENTRIFUGAL FORCE THROWING LIQUIDS TO OUTER WALL
LIQUIDS DISCHARGED IN VENT FLOW
FIG. 3
Cyclone Filter/Centrifugal Filter
II LIQUID OUTLET
LIQUID & VAPOR IN
FIG. 5
Combination Condensor/Separator
sample. A typical rotameter consists of a ball or float mounted in a tapered tube. The reading is proportional to fluid density and viscosity which may vary with the composition of the fluid. 6.1.6.1 The rotameter should be located downstream of the analyzer and used as an indicator of flow and system cleanliness. A clean tube and a freely moving ball is an indicator of a clean system. 6.1.7 Typical natural gas sample system. (See Fig. 6.) 6.1.8 Compressed natural gas sample system. (See Fig. 7.)
VAPOR OUT COALESCING-~ MEMBRANE
LIQUIDS OUT ~LYZ
FIG. 4
q
Coalescing Filter
VAPOR BYPASS
J device. The condensed liquid phase is separated by gravity and removed from the bottom of the separator. (See Fig. 5.) 6.1.3.1 Since this process removes part of the sample, the impact on sample composition must be considered. 6.1.3.2 The condenser/separator should be located immediately upstream from the analyzer. 6.1.4 Pressure regulators are required to reduce and regulate pressure between the sampling point and the analyzer. The regulator must be constructed of the proper materials to allow for the corrosive nature of the sample. 6.1.4.1 A combination sample probe and regulator with thermal fins around the probe could be used to minimize the Joule-Thompson effect. 6.1.5 Pressure gages should be installed downstream of the pressure regulator. Since the sensing element of these devices (Bourdon tube) consists of unswept volume, the pressure gage should be installed either in a bypass line or after the analyzer. 6.1.6 Rotameters are used to indicate the flow rate of the
.L
l=
VENT
M ANALYZERFLOW ~)(
,C-ILTER
Y
P
~ A S
REO'D)= VENT STR,~I I IN ~ STREAM2 IN
~
~
COALESCfflG LIQUID DF,'AN I ER
~'~
UOUtOORAtN ~ STANDARDIN
FLOWCONTROL
IlL
DOUBLEBLOCK& BLEED STREAMSWITCHING
STREAMSWITCH VALV~VENT
HEATEDENCLOSURE USEDAS REQ'D
FIG. 6 Typical Natural Gas Sampling System
914
~) D 5503 ATM PRESSURE
LYZE; STREAM 1 IN
~
~
~>~I ~ - - I
- ~ - TO.MPLE CONDHIONING
STREAM 2 IN
DUAL-STAGEPRESSURE
-
-
REDUCTION
-
~20
SAMPLE PRESSURE PSIG
SYSTEM
400
....
,/.'ToBE
TOSAMPLE CONDIIIONING SYSTEM
~
]
DeC/M,.
100 N LAG TIME = L x V = 75 WIN fs
HEATED ENCLOSURE
FIG. 7
HIGH PREJ':,URE GAS SAMPLE TRANSPORT LINE
Pressure Reduction System for Compressed Natural Gas (CNG) SAMPLEPRESSURE 400PSIG
7. Materials 7.1 Many of the common sample system components are constructed of metals such as 316 stainless steel, Hastelloy, and Monel and compatible plastics such as Kel-F, Teflon, and Kynar. 7.1.1 The sample-handling and conditioning system should be constructed of material capable of resisting corrosion from the sample and the environment. 7.l.l.1 Sample system components should be chosen carefully to avoid corrosion or adsorption by the sample. 7.1.1.2 If sour gas (gas that contains hydrogen sulfide or carbon dioxide, or both) is suspected, NACE Standard MR-01-75 should be followed. 7.2 The sample-handling and conditioning system should contain the sample under the most severe conditions of pressure, temperature, and vibration that the pipeline will experience during normal and upset conditions.
VL(P + Prom) F,,P,,,
F-~ ,%T;E L ~
~
DOCC/MIN
--
LAG TIME = L F s V
= 7-I/2
MIN
O~
HIGH PRESSURE GAS SAMPLE TRANSPORT UNE WITH FAST LOOP
~MPLE PRESSURE
400PSIG
2000CC/MIN I~
00 CC/MIN
TUBE [
1/4" 100 E'r
LAG TIME = L Fs V = I MIN
HIGHPRESSURECA',SAMPLETRANSPORTLINEWITHFASTLOOP
AND PRE%%URE REDUCTION AT SAMPLE POINT (TEMPERATURE CORRECTIONS )lAVE BEEN )GNORED IN THE CALCUALTION OF LAG TIME)
FIG. 8
Example Calculations of Lag Time
L = La + Leq (2) where: L = equivalent length of sample line, m, Ld = length of sample line, m, and Leq = equivalent length of valves and fittings, m. 8.3 Calculation of sample line size is a trial and error process: 8.3.1 Select a sample line size that meets the flow rate needs of the analyzer. 8.3.2 Calculate the Reynold's number, the ratio of iner= tial=to=viscous forces by:
8. Calculation 8.1 Sample transport time, or lag time, hag, is a function of the sample line length and diameter, the absolute pressure in the line, and the sample flow rate. Lag time is calculated as follows: l/ae =
~ 2000CC/MIN
( 1)
where: hag = sample transport time, rain, V = volume of sample per unit length, cm3/m, L = equivalent length of sample length, m, P = sample pressure, N/m 2, P,,,, = atmospheric pressure, N/m 2, and Fa = actual average flow rate of the sample, cm3/min. 8.1.1 E x a m p l e - - C o n s i d e r a sample point located 100 ft away from an analyzer requiring 200 cm3/min of sample. Using standard conditions and 0.19 in. inside diameter tubing, a lag time of 75 min can be calculated. By increasing the sample flow to 2200 cm3/min and splitting the excess sample to a high-speed loop, the lag time decreases to 7.5 min. The sample pressure should be reduced at the analyzer. 8.1.2 Reducing the pressure at the sample point rather than the analyzer can also decrease the lag time. For a pressure reduction from 400 psig to 40 psig, the sample flow should be 2000 cm3/min to compensate for the increase in sample volume. (See Fig. 8.) 8.2 The equivalent length of sample line is calculated by the following expression (see Ref (3) for more information):
Re = a~,___a ))
(3)
where: R e = Reynold's number, p = fluid density, Kg/m 3, ~t = fluid velocity, m/s, d = diameter of the pipe, m, and )7 = viscosity of the fluid, Ns/m 2. 8.3.3 Calculate the pressure drop using Darcy's equation (see (3) for more information): dp = fpLu2
2dg where: dp -- pressure drop in the line, N/m 2, f = frictional factor from Moody's tables, a = fluid density, Kg/m 3, L = equivalent length of sample line, m, 915
(4)
4@) D 5503 be calculated without the aid of a computer by the following procedure: 8.4.1.1 Assume a dew point temperature. Using a DePriester chart, determine the K at the highest pressure present in the sample line and the assumed dew point for each component in the sample (see Ref (6) for more information). 8.4.1.2 Calculate the mole fraction, y, for each component in the vapor phase. 8.4.1.3 Calculate the mole fraction, x, for each component in the liquid phase. At the dew point, the summation of the xi's should be between 0.95 and 1.0. 8.4.2 The dew point calculation depends upon the accuracy of the stream composition. Small errors in the composition (especially in the heavier hydrocarbons) will cause large errors in the hydrocarbon dew point. 8.4.3 The dew point could be determined using a Bureau of Mines Type chilled mirror hygrometer (see Test Method D 1142 for more information).
u = velocity of the fluid, m/s, d = diameter of the line, m, and g = acceleration of gravity, 9.81 m/s 2. 8.3.4 The available pressure drop should be compared with the calculated pressure drop. If the calculated pressure drop is too great, then select a larger sample line and repeat lag time, equivalent length, and pressure drop calculations. 8.3.5 The majority of sample transport problems are solved by application of prior experience and by use of tables relating velocity to pressure drop for different sample line diameters (see Refs (4) and (5) for more information). 8.4 The dew point calculation relies on the use of distribution coefficients, Ki, which are defined as the ratio of the mole fraction of the component in the vapor phase, Y,, to the mole fraction in the liquid phase, xi. K, =
xj
(5)
8.4.1 Whenever possible, dew point should he calculated using a physical properties software package. Dew point can
9. Keywords
9.1 natural gas; pipeline instrumentation
REFERENCES (4) Moody, L. F., "Friction Factors for Pipe Flow," Trans. Am. Soc. Mech. Engnrs., 66:671-678 (I 944) (5) Clevett, K. J., Process Analyzer Technology, NY: John Wiley and Sons (1986) (6) DePriester, K., Chem. Eng. Progr. Syrup. Ser. 7, 49: ! (1953)
(1) Cornish, D. C., Jepson, G., and Smarthwaite, M. J., Sampling Systems for Process Analyzers, London: Butterworth (1981) (2) Annino, R. and Villalobos, R., Process Gas Chromatography, ISA Research Triangle Park, NC: (1992) (3) "Flow of Fluids through Valves, Fittings and Pipe," Technical Paper No. 410, Chicago, Ill: Crane Co., (1978)
The American Society for Testing and Materials takes no position respecting the vatld/ty of any patent rights asserted in connection with any Item mentioned in this standard. Users of this standard are expressly advised that datarminat/on of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision st any time by the responsible technical committee and must be reviewed every five years and if not revised, s/thar reapproved or withdrawn. Your comments are Invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful cons/daratlon at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
916
(~)
Designation: D 5504 - 94 Standard Test Method for Determination of Sulfur Compounds in Natural Gas and Gaseous Fuels by Gas Chromatography and Chemiluminescence I This standard is issued under the fixed designation D 5504; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last re.approval. A superscript epsilon (0 indicates an editorial change since the last revision or re.approval.
3.1.1 A common abbreviation of hydrocarbon compounds is to designate the number of carbon atoms in the compound. A prefix is used to indicate the carbon chain form, while a subscript suffix denotes the number of carbon atoms (for example, normal decane = n-C~o; Iso-tetradecane ffi I-CI4). 3.1.2 Sulfur compounds are commonly referred to by their initials (chemical or formula), for example, dimethyl sulfide = DMS; carbonyl sulfide = COS.
1. Scope 1.1 This test method provides for the determination of individual volatile sulfur-containing compounds in gaseous fuels including natural gas. The detection range for sulfur compounds, reported as picograms sulfur, is ten (10) to one million (1,000,000), This is equivalent to 0.01 to 1,000 mg/m 3, based upon the analysis of a 1 cc sample. 1.2 The test method does not purport to identify all individual sulfur species. The detector response to sulfur is equimolar for all sulfur compounds within the scope (1. I) of this test method; thus unknown individual compounds are determined with equal precision to that of known compounds. Total sulfur content of samples can be estimated from the total of the individual compounds determined. 1.3 The values stated in SI units are to be regarded as standard. The values stated in inch-pound units are for information only. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
4. Summary of Test Method 4.1 The analysis of gaseous sulfur compounds is difficult because of the reactive nature of these materials. They pose problems both in sampling and analysis. Analysis is ideally performed on-site to eliminate potential sample deterioration. Sampling must be done using containers proven to be nonreactive, such as Tedlar bags. Laboratory equipment must also be inert and well conditioned to ensure reliable results. Frequent calibration using stable standards is required in sulfur analysis. 4.2 A one cc sample of the fuel gas to be analyzed is injected into a gas chromatograph where it is passed through a 60 meter, megabore, thick film, methyl silicone liquid phase, open tubular partitioning column, and separated into its individual constituents. 4.3 Sulfur Chemiluminescence Detection--As sulfur compounds elute from the gas chromatographic column they are combusted in a flame ionization detector (liD). These combustion products are collected and transferred to a .sulfur chemiluminescence detector (SCD). This detection technique provides a highly sensitive, selective, and linear response to volatile sulfur compounds and may be used simultaneously while the usual fixed gas and hydrocarbon determinations are being made. 4.4 Other Detectors--This test method is written primarily for the sulfur chemiluminescent detector but other sulfur specific detectors can be used provided they have sufficient sensitivity, response to all sulfur compounds of interest, and do not suffer significant hydrocarbon interference. 4.4.1 Lead Acetate Rate of Stain Detector--This detector relies on all sulfur compounds from the column passing through a high temperature hydrogenator. All sulfur compounds are transformed to hydrogen sulfide and sent to a hydrogen sulfide detector. The detector uses optical measurement of the rate of darkening of a lead acetate tape to detect the eluting sulfur compound. 4.4.2 Electrochemical Detectors--Electrochemical detectors specific to sulfur may be used.
2. Referenced Documents
2.1 A S T M Standards: D 1072 Test Method for Total Sulfur in Fuel Gasese D 1145 Method of Sampling Natural Gas 2 D 1945 Test Method for Analysis of Natural Gas by Gas Chromatography 2 D 2725 Test Method for Hydrogen Sulfide in Natural Gas (Methylene Blue Method) 2 D 3031 Test Method for Total Sulfur in Natural Gas by Hydrogeneration 2 D 4468 Test Method for Total Sulfur in Gaseous Fuels by Hydrogenolysis and Rateometric Colorimetry2 D 4626 Practice for Calculation of Gas Chromatographic Response Factors 3 E 594 Practice for Testing Flame Ionization Detectors Used in Gas Chromatography 4 3. Terminology 3.1 Abbreviations: I This test method is under the jurisdiction of ASTM Committee D-3 on Gaseous Fuels and is the direct responsibility of Subcommittee D03.05 on Determination of Special Constituents of Gaseous Fuels. Current edition approved Feb. 15, 1994. Published April 1994. 2 Annual Book of ASTM Standards, Vol 05.05. 3 Annual Book of ASTM Standards, Vol 05.02. ";Annual Book of ASTM Standards, Voi 14.01.
917
@
o
sso4
NOTE l---Carbonylsulfide is not detected by some of these detectors because of its stability. 4.3 Flame Photometric Detectors~Flame photometric detectors can be used if sensitivity and hydrocarbon interference are not a problem.
6.1.4.1 F/D--The detector must meet or exceed the typical specifications given in Table 1 of Practice E 594 while operating in the normal mode as specified by the manufacturer. The detector must be capable of operating continuously at a temperature equivalent to the maximum column temperature employed. Connection of the column to the detector must be such that no temperature below the column temperature exists. The detector design must be such to allow the insertion of the SCD sampling probe into the flame without interrupting the detection of the hydrocarbon response. 6.1.4.2 SCD--The sulfur chemiluminescence detector shall meet or exceed the following specifications: (1) greater than l0 s linearity, (2) less than 5 pg S/s sensitivity, (3) greater than 106 selectivity for sulfur compounds over hydrocar. bons, (4) no quenching of sulfur compound response, and (5) no interference from co-eluting compounds at the usual GC sampling volumes. 6.1.4.3 As sulfur compounds elute from the gas chromatographic column they are combusted in a hydrogen-rich flame of a flame ionization detector (liD) producing numerous combustion products, one of which is sulfur monoxide (Reaction 1). These combustion products are collected and removed from the flame using a ceramic sampling tube (probe) interface and transferred under a vacuum through a flexible tube to the reaction chamber of the sulfur chemiluminescence detector (SCD). Sulfur monoxide is then sensitively detected by an ozone/sulfur monoxide chemiluminescent reaction to form electronically excited sulfur dioxide, which relaxes with emission of light in the blue and the ultraviolet regions of the spectrum (Reaction 2). Figure O presents a simple schematic of the detector configuration. Sulfur compound + hydrogen/air flame ~ SO + products (1) SO + O~ --, SO2 + O2 + Hv (2) where Hv ffi chemiluminescent light energy. 6.2 Column--A 60 m x 0.54 mm ID fused silica open tubular column containing a 5 I~m film thickness of bonded methyl silicone liquid phase is used. The column shall provide retention and resolution characteristics as listed in Table 2 and illustrated in Figure 1. The column will also demonstrate a sufficiently low liquid phase bleed at high temperature such that no loss of the SCD sulfur response is encountered while operating the column at 200"C. 6.3 Data Acquisition: 6.3.1 RecordermA 0 to 1 mV range recording potentiometer or equivalent, with a full-scale response time of 2 s or less can be used. 6.3.2 lntegratormThe use of an electronic integrating
5. Significance and Use 5.1 Many sources of natural gas and petroleum gases contain varying amounts and types of sulfur compounds which are odorous, corrosive to equipment, and can inhibit or destroy catalysts employed in gas processing. 5.2 Small amounts (for example, 1-2 ppm) of sulfur odorant compounds are added to natural gas and LP gases for safety purposes. Some odorant compounds are not absolutely stable and tend to react to form more stable compounds having lower odor thresholds. Sulfur odorant levels are therefore analyzed to help ensure proper safety with fuel gases. 5.3 Current Analytical Methods~Gas chromatography (GC) is commonly used to determine the fixed gas and organic component composition of natural gas (Test Method D 1945). Other standard methods for the analysis of sulfur in fuel gases include Test Methods D 1072, D3031, and D 4468 for total sulfur and Test Method D 2725 for hydrogen sulfide. 6. Apparatus 6.1 Chromatograph--Any gas chromatograph that has the following performance characteristics can be used: 6.1.1 Column Temperature Programmer--The chromatograph must be capable of linear programmed temperature operation over a range of 30 to 200"C, in programmed rate settings of 0.1 to 30"C/min. The programming rate must be sufficiently reproducible to obtain retention time repeatability of 0.05 min (3 s) throughout the scope of this analysis. 6.1.2 Sample Inlet SystemmThe sample inlet system must be capable of operating continuously at a temperature up to the maximum column temperature employed. A splitting injector is recommended, capable of splitless or accurate split control in the range of 10:1 to 50:1. An automated gas sampling valve is also recommended. The inlet system must be well conditioned and evaluated frequently for compatibility with trace quantities of reactive sulfur compounds. 6.1.3 Carrier and Detector Gas Control--Constant flow control of carrier and detector gases is critical to optimum and consistent analytical performance. Control is best provided by the use of pressure regulators and fixed flow restrictors. The gas flow rate is measured by any appropriate means and the required gas flow indicated by the use of a pressure gage. Mass flow controllers, capable of maintaining gas flow constant to ± 1% at the required flow rates can also be used. The supply pressure of the gas delivered to the gas chromatograph must be at least 69 kPa (10 psig) greater than the regulated gas at the instrument to compensate for the system back pressure. In general, a supply pressure of 552 kPa (80 psig) will be satisfactory. 6.1.4 Detector--Both a flame ionization detector (liD) and a sulfur chemiluminescence detector (SCD) are used. Other detectors as in 4.4 will not be covered in detail in this test method.
TABLE 1
Typical Gas Chromatographic OperaUng Parameters
Injector. gas sample loop: 150°C Injector. splitless: Flame ionization detector: 2500C
1.0 cc 150=C 100 ',r. sample to column H2: 200 cma/min Air: 400 cma/min Make-up gas (He): 20 crna/min SCD: output at 0--1 V cell pressure at 8.7 torr Column Oven: 1.5 min at 30°C 15.0=/min to 200*C hold at 200°C as required Carrier gas (helium): adjust to methane retention time of 1.10 min 14.5 kPa (20 psig) or approximately 11 cma/min
918
q~) D 5504 TABLE 2
6.3.2.5 External standard calculation and data presentation.
Retention T l m e - - 4 u SPB1
Conditions as in Table 1 Compound Methane Ethylene Ethane Hydrogen Sulfide Propylene Carbon}4 Sulfide Propane Sulfur Dioxide I-Butane Butene-1 n-Butane Methanethiol t-Butene-2 2,2-DMO3 ¢-IButene-2 3-Me-Butene-1 I-Pentane Pentene-1 Ethanethiol ~ e - 1 n-Pentane Isoprene t-Pentene-2 Dimethylsulfide o-Pentene-2 2-Me-Butene-2 Carbon Disulfide 2,2.DMO4 i-Propanethiol Cyclopentene 3-MePentadiene CP/2,3-DMO4 2-MO5 t-Butanethiol 3-MO5 Hexene-1 n4~oanethiol n-Hexane MethylEthylSulfide MeCyC5 Benzene s-Butanethiol
Ave. RT mln 1.458 1.733 1.730 2.053 2.550 2.586 2.679 2.815 4.422 5.263 5.578 5.804 5.938 6.009 6.409 7.463 8.035 8.500 8.583 8.717 8.860 8,963 9.096 9.117 9.321 9.463 9.617 9.898 10.222 10.392 10.525 10.733 10.883 11.278 11.269 11.392 11.625 11.720 11.779 12.457 13.154 13.154
Compound ?S n-Octane ?S S ?S ?-EtThiophene ?S ?S ?S ?S m&p-Xylene ?S ?S ?S o-Xylene ?S n-None ?S ?S DIEthylDiSulfide ?S ?S ?S ?S ?S 2,2,4-TriMeBz n.Decane ?S ?S ?S ?S n-Undecane ?S ?S ?S n-Dodecane Beflzothlophene n-Tridecane MeBzThiophene MoBzThiophene MeBzThiophene MeBzThiophene
Ave. R'l" mln 16.363 16.423 16.425 16.592 16.692 16.983 17.183 17.319 17.631 17.754 17.788 17.913 18.053 18.139 18.279 18.450 18.448 18.567 18.642 18.767 18.911 19.008 19.125 19.292 19.979 20.227 20.308 20.550 21.396 21.733 21.808 22.033 22.208 22.417 23.046 23.631 23.717 25.134 25.225 25.328 25.433 25,550
7. Reagents and Materials 7.1 Sulfur Compound Standards--Gaseous permeation tube standards shall be used for all sulfur compounds to be determined. 7.2 Permeation tubes will be weighed to the nearest 0.1 mg on a monthly basis and standard concentration calculated by weight loss and dilution gas flow rate. 7.3 Compressed Cylinder Gas Standards--As an alterna. five, blended gaseous sulfur standards may be used if a means to ensure accuracy and stability of the mixture is available. These mixtures can be a source of error because of instability. NOTE 4: Warning--Sulfur compounds may be flammable and harmful or fatal if ingested or inhaled.
7.4 Carrier Gas--Helium or nitrogen of high purity (Warning--See Note 5). Additional purification is recommended by the use of molecular sieves or other suitable agents to remove water, oxygen, and hydrocarbons. Available pressure must be sufficient to ensure a constant carrier gas flow rate (see 6.1.3). NOTE 5:,Warning--Helium and nitrogen can be compressed gases under high pressure.
7.5 Hydrogen--Hydrogen of high purity (for example, hydrocarbon free) is used as fuel for the flame ionization detector (FID) (Warning--See Note 6). NOTE 6: Warning--Hydrogen is an extremely flammable gas under high pressure.
7.6 Air--High purity (for example, hydrocarbon free) compressed air is used as the oxidant for the flame ionization detector (liD) (Warning--See Note 7). NOTE 7: Warning--Compressed air can be a gas under high pressure and supports combustion.
device or computer is recommended. A dual channel system is useful for simultaneous presentation of both the l i d and SCD signals. The device and software must have the following capabilities: 6.3.2.1 Graphic presentation of the chromatogram. 6.3.2.2 Digital display of chromatographic peak areas. 6.3.2.3 Identification of peaks by retention time or relative retention time, or both. 6.3.2.4 Calculation and use of response factors.
8. Preparation of Apparatus and Calibration 8.1 Chromatograph--Placein service in accordance with the manufacturer's instructions. Typical operating conditions are shown in Table 1. Hydrogen and air flows are critical for the FID reducing flame to give the SCD optimum sensitivity. 8.2 SCD--Place in service in accordance with the manufacturer's instructions. With the l i d flame ignited, put the probe assembly in place. The probe placement location is critical to maximum sensitivity. Ensure proper location before continuing. After sufficient equilibration time (for example, 5-10 rain), adjust the detector output signal or integrator input signal to approximately zero. Monitor the signal for several minutes to verify compliance with the specified signal noise and drift. 8.2.1 Sample Injection--Inject 1.0 cc from a sample loop of the calibration standard gas mix that covers the concentrations of interest. 8.2.2 Detector Response Calibration--Analyze the calibration gas and obtain the chromatograms. Calculate the relative response factor for each sulfur compound:
pJ
|.,., .
:
;~L
r,a~
~
Ix/
N. ~
II
la,
H .
.
.
,
.
.
.
.
2
.
4 T i m e
FIG. 1
.
.
, 6
.
.
.
,
,
1
_
8
( m l n . )
Standard Perm Tube Analysis Run
r,, = (c./A,,)
919
(3)
~1~ D 5504 TABLE
2000~ 19OO:
Compound
3 SulfurGas Standard
Mol. Wt. Density BP°C
"/oS
E
1,008". 1700~
B~"
~..
1500"
w ~ U
16
P¢ =
t4eei 1300;
j
, =,
=
,
FIG. 2
4
I
Time
'l .
-~
d
l-
i
.
Hydrogen Sulfide (H=S) Carbonyl Sulfide (COS) Methanethlol (MESH) Ethanethiol (EtSH) Dlmethylsulflde (DMS) Carbon Disulfide (CS=) 2.Propanethiol (IPrSH) t-Butanethiol (tBSH) 1-Propane~lol (nPrSH) IVlethylethylsulflde(MES) Thlophene (TP) s-Butanethi~ (s-BuSH) kButanethlol (I-BuSH) Olethylsulflde (DES) n-Butenethiol (n-BuSH) Dlmethyk:llsulflde(DMDS) DlethyMleulflde (DEDS)
i
(mln.)
Natural c o l A n a l y l i l - S u l f u r Compounds
P.OE43
S.0£4~
34.08
1.1857 1.24 48.110 0.8665 62.134 0.8391 62.134 0.9483 76.14 -76.160 0.8143 64.220 0.8002 76.160 0.3415 76.160 0.8422 54.14 1.07 90.186 0.8299 90.166 0.8343 90.190 0.8362 90,186 0.9416 94.200 1.6825 122.252 0.9931
60.35
--6.2 35.0 37.3
~ 52.6 65.0 67.0 67.0 84.16 65.0 68.7 92~) 98.5 109.7 154.0
94.06 53.37
68.65 51.61 51.61 54.23 42.10 49.93 42.10 42.10
35.03 35.66 35.56 35.55 35.56 68.35 52.46
(Conversion) Mg/M3per PPMV 1.35 2.46 1.97 2.54 2.54 3.11 3.11 2.62 3.11 3.11 3.44 3.69 3.69 3.69 3,69 3.85 5.00
5.0(4~
TABLE 4
4.9(4~ 3.0[4~
g=
2.O(4~
u
J:
~ J:
-cs'S-_cT,s__ca,s_
100001, .o^ 8
FIG. 3
i
.A
I 4"
i -
. "
Time
|
I g
(min.)
"
i
"
"
" |~
Calibration Table
SIEVERS 6 PTUBES NEW DETuMEGABORE/2OPSIG He 516/91 SPLITLJESS Calibration file: DATA:SVPT.Q Last Update: 24 Jul 91 5:37 pm Reference Peak Window: 5.00 "/, of Retention Time Non-Reference Peak Window: 5.00 ~ of Retention Time Sample Amount: 0.000 Uncallbrated Peak RF: 60.00e-6 Multiplier: 1.000 " |i
Natural Gas Analysis-Hydrocarbon Compounds
where: F, ffi response factor of compound. C, ffi concentration of the sulfur compound in the mixture. A, = peak area of the sulfur compound in the mixture. The response factor (F,) of each single sulfur compound should be within 10 % of F, for dimethyl sulfide. Figure 1 provides an example of a typical chromatogram and Table 4 shows the data and calibration report. Table 3 contains information useful for calibration calculations.
Rot Time
Ph#
Signal Descr
Amt PPMV
1.461 1.595 2.861 3.529 3.809 4.185 4.481 5.179 5.521 6.738 7.129 7.868 7.912 9.017
I 2 3 4 5 6 7 8 9 10 11 12 13 14
GC Signal I GC Signal 1 GC Signal 1 GC Signal 1 GC Signal 1 GC Signal 1 GC Signal 1 GC Signal 1 GC Signal 1 GC Signal 1 GC Signal 1 GC Signal 1 GC Signal 1 GC Signal I
0.9100 0.2610 0.3570 0.4150 0.4943 0.2269 0.3904 0.6140 2.600 0.9670 1.226 1.135 0.07660 1.558
cvl RespFact
Pk-Type Partial Name 1 59.60e-.6 I H2S 1 35.~o-6 1 COS 1 50.11e-6 1 MTM 1 50.28e-6 1 ETM 1 49.02e-6 1 DMS 1 0001001 1 CS2 1 50.04e-6 1 1PM 1.49.99e-6 1 TBM 1 50.00e-6 1 MES 1 49.29e-6 1 SBM 1 48.81e-6 1 DES 1 49.99e-6 1 NBM 1 0.0001000 1 DMDS 1 49.99e-6 1 THT
puter-based chromatographic data system. Examine the graphic display or digital data for any errors (for example, over-range component data).
9. Procedure
9. l Sampling and Preparation of Sample Aliquots: 9.l.l Gas Samples--Samples will be supplied to the laboratory in specially conditioned high-pressure sample containers or in Tedlar bags at atmospheric pressure. Such bags for H2S analysis must be run within 24 h of sampling. 9.2 Table 1 lists the gas chromatograph operating parameters. Table 2 provides a partial listing of the retention times of light sulfur compounds. Figures 1 and 2 illustrate typical analyses of a standard mixture and natural gas. 9.3 External Standard Calibration--At least once a day or as frequently as deemed expedient, analyze the calibration standard mix and determine standard response factors (see 10.1). 9.4 Sample Analysis--Purge the lines from the sample container through the sample loop in the gas chromatograph. Inject 1 cc with a gas sampling valve as in 8.2.1. If the sample size exceeds the linear range of the detector a split injection should be used. Run the analysis per the conditions specified in Table 1. Obtain the .chromatographic data via a potentiometric record (graphic), digital integrator, or corn-
10. Calculations 10.1 Determine the chromatographic peak area for components and use the response factors obtained from the calibration run to calculate amounts of sulfurs present. Example: Assume 1.0 ppmv of dimethyl sulfide, DMS, injected into a 1.0 cc sample loop with no split. 1 ppmv DMS = 2.54 mg/M 3 (Table 3) 2540 pg x 51.61% S ffi 1310 picog S/peak If area is found to be 15,850 counts-response factor picograms (S/peak) is 1310/15850 -- 8.27 x 10-2 (in terms of picograms sulfur per peak) or response factor (ppmv DMS sample) = 1.0/15850 = 63 x 10-6 (in terms of ppmv of sulfur compound in sample) NOTE 8--Since detector response is proportional to weight sulfm', all mono sulfur compounds (COS, H2S, DMS, etc.) will have approximately the same response factor for picograms S or ppmv (see 8.2.2).
920
I~) D 5504 11. Report 1 I. 1 Report the identification and concentration of each individual sulfur compound. The sum of all sulfur components detected to the nearest picogram, calculated as sulfur (pg S) can be used to calculate the total sulfur.
12. Precision and Bias 12.1 Precision--The precision of this test method as determined by the statistical examination of the interlaboratory test results is as follows: 12.1.1 Repeatability---The difference between successive test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and
correct operation of the test method, exceed the following values by only one case in twenty. (Experimental results to be determined) 12.1.2 Reproducibility--The difference between two single and independent results obtained by different operators working in different laboratories on identical test matefial would, in the long run, exceed the following values only one case in twenty. (Experimental results to be determined) 12.2 B/as--The procedure in Test Method D 5504 for the analysis of sulfur compounds in petroleum and petroleum products by gas chromatography has no bias. 13. Keywords 13.1 chemiluminescence detection; gas chromatography; sulfur compounds
The American Society for Testmg and Materials takes no posltion respecting the vahdity of any patent rtghts asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the vahdlty of any such patent rtghts, and the risk of infringement of such rights, are entirely their own responsibility. This standard is sublect to revision at any time by the responsible technical committee and must be reviewed every hve years and if not revised, etther reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical commfftee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Drtve, West Conshohocken, PA 19428.
921
(t~T~ Designation: D 5580 - 95 Standard Test Method for Determination of Benzene, Toluene, Ethylbenzene, p/m-Xylene, o-Xylene, C9 and Heavier Aromatics, and Total Aromatics in Finished Gasoline by Gas Chromatography This standard is issued under the fixed designation D 5580; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsdon (c) indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 This test method covers the determination of benzene, toluene, ethylbenzene, the xylenes, C9 and heavier aromatics, and total aromatics in finished motor gasoline by gas chromatography. 1.2 The aromatic hydrocarbons are separated without interferences from other hydrocarbons in finished gasoline. Nonaromatic hydrocarbons having a boiling point greater than n-dodecane may cause interferences with the determination of the C9 and heavier aromatics. For the C8 aromatics, p-xylene and m-xylene co-elute while ethylbenzene and o-xylene are separated. The C9 and heavier aromatics are determined as a single group. 1.3 This test method covers the following concentration ranges, in liquid volume %, tbr the preceding aromatics: benzene, 0.1 to 5 %; toluene, 1 to 15 %; individual C8 aromatics, 0.5 to 10 %; total C,) and heavier aromatics, 5 to 30 %, and total aromatics, l0 to 80 %. 1.4 Results are reported to the nearest 0.01% by either mass or by liquid volume. 1.5 Many of the common alcohols and ethers that are added to gasoline to reduce carbon monoxide emissions and increase octane, do not interfere with the analysis. Ethers such as methyl tert-butylether (MTBE), ethyl tert-butylether (ETBE), tert-amylmethylether (TAME), and diisopropylether (DIPE) have been found to elute from the precolumn with the nonaromatic hydrocarbons to vent. Other oxygenates, including methanol and ethanol elute before benzene and the aromatic hydrocarbons, l-Methylcyclopentene has also been found to elute from the precolumn to vent and does not interfere with benzene. 1.6 The values stated in SI units are to be regarded as standard. The values given in parentheses are provided for information only; they may not be exact equivalents. 1.7 This standard does not purport to address all of the
D 1298 Practice for Density, Relative Density, (Specific Gravity) or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method 2 D 4052 Test Method for Density and Relative Density of Liquids by Digital Density Meter 3 D4057 Practice for Manual Sampling of Petroleum and Petroleum Products 3 D 4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards 3 E 355 Practice for Gas Chromatography Terms and Relationships 4 3. Terminology
3.1 Descriptions of Terms Specific to Th& Standard." 3.1.1 aromatic--any organic compound containing a benzene ring. 3.1.2 low-volume connector--a special union for connecting two lengths of narrow bore tubing 1.6-mm (0.06-in.) outside diameter and smaller; sometimes this is referred to as zero dead volume union. 3.1.3 narrow bore tubingmtubing used to transfer components prior to or after separation; usually 0.5-ram (0.02-in.) inside diameter and smaller. 3.1.4 sprit ratio--in capillary gas chromatography, the ratio of the total flow of carrier gas to the sample inlet versus the flow of the carrier gas to the capillary column, expressed by: split ratio = ( S + ( ' ) / C (l) where: S = flow rate at the splitter vent and C = flow rate at the column outlet. 3.1.5 1,2,3-tris-2-cyanoethoxypropane (TCEP)--a polar gas chromatographic liquid phase. 3.1.6 wall-coated open tubular (WCOT)ma type of capillary column prepared by coating the inside wall of the capillary with a thin film of stationary phase.
sa.[~,ty concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
4. Summary of Test Method 4.1 A two-column chromatographic system equipped with a column switching valve and a flame ionization detector is used. A reproducible volume of sample containing an appropriate internal standard such as 2-hexanone is injected onto a precolumn containing a polar liquid phase
2. Referenced Documents 2.1 ASTM Standards: t This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcom. mittee D02.04.0L on Gas Chromatography. Current edition approved Sept. 10, 1995. Pubhshed November 1995. Originally published as D 5580 - 94. Last previous edition D 5580 - 94.
2 Annual Book of ASTM Standards, Vol 05.01 3 Annual Book of ASTM Standards, Vol 05.02. a Annual Book of ASTM Standards, Vol 14.02.
922
of precise control when column head pressures and flow rates are low. 6.1.2 Sample Introduction System, capable of introducing a representative sample into the gas chromatographic inlet. Microlitre syringes and automatic syringe injectors have been used successfully. 6.1.3 Inlet System, (splitting type)--Split injection is necessary to maintain the actual chromatographed sample size within the limits required for optimum column efficiency and detector linearity. 6.1.3.1 Some gas chromatographs are equipped with oncolumn injectors and autosamplers which can inject submicrolitre sample sizes. Such systems can be used provided that column efficiency and detector linearity are comparable to systems with split injection, 6.1.4 Detector--A flame ionization detector (Detector A) is employed for quantitation of components eluting from the WCOT column. The flame ionization detector used for Detector A shall have sufficient sensitivity and stability to detect 0.01 volume % of an aromatic compound. 6.1.4.1 It is strongly recommended that a thermal conductivity detector be placed on the vent of the TCEP precolumn (Detector B). This facilitates the determination of valve BACKFLUSH and RESET times (l 1.5) and is useful for monitoring the separation of the polar TCEP precolumn. 6.1.5 Switching and Backflushing Valve, to be located within a temperature-controlled heated zone and capable of performing the functions in accordance with Section I l, and illustrated in Fig. 1. The valve shall be of low internalvolume design and not contribute significantly to deterioration of chromatographic resolution. 6.1.5.1 A 10-port valve with 1.6-mm (0.06) outside diameter fittings is recommended for this test method. Alternately, and if using columns of 0.32-mm inside diameter or smaller, a valve with 0.8-mm (0.03-in.) outside diameter fittings should be used. 6.1.5.2 Some gas chromatographs are equipped with an auxiliary oven which can be used to contain the valve. In such a configuration, the valve can be kept at a higher temperature than the polar and nonpolar columns to prevent sample condensation and peak broadening. The columns are then located in the main oven and the temperature can be adjusted for optimum aromatic resolution. 6.1.5.3 An automatic valve switching device is strongly recommended to ensure repeatable switching times. 6.2 Data Acquisition System: 6.2.1 Integrator or Computer, capable of providing realtime graphic and digital presentation of the chromatographic data are recommended for use. Peak areas and retention times can be measured by computer or electronic integration. 6.2.1.1 It is recommended that this device be capable of performing multilevel internal-standard-type calibrations and be able to calculate the correlation coefficient (r 2) and linear least square fit equation for each calibration data set in accordance with 12.4. 6.3 Chromatographic Columns (two columns are used): 6.3. l Polar Precolumn, to perform a pre-separation of the aromatics from nonaromatic hydrocarbons in the same boiling point range. Any column with equivalent or better
(TCEP). The C 9 and lighter nonaromatics are vented to the atmosphere as they elute from the precolumn. A thermal conductivity detector may be used to monitor this separation. The TCEP precolumn is backflushed immediately before the elution of benzene, and the remaining portion of the sample is directed onto a second column containing a nonpolar liquid phase (WCOT). Benzene, toluene, and the internal standard elute in the order of their boiling points and are detected by a flame ionization detector. Immediately after the elution of the internal standard, the flow through the nonpolar WCOT column is reversed to backflush the remainder of the sample (C 8 and heavier aromatics plus C w and heavier nonaromatics) from the column to the flame ionization detector. 4.2 The analysis is repeated a second time allowing the C~2 and lighter nonaromatics, benzene and toluene to elute from the polar TCEP precolumn to vent. A thermal conductivity detector may be used to monitor this separation. The TCEP precolumn is backflushed immediately prior to the elution of ethylbenzene and the remaining aromatic portion is directed into the WCOT column. The internal standard and C8 aromatic components elute in the order of their boiling points and are detected by a flame ionization detector. Immediately after o-xylene has eluted, the flow through the nonpolar WCOT column is reversed to backflush the C,~ and heavier aromatics to the flame ionization detector. 4.3 From the first analysis, the peak areas of benzene, toluene, and the internal standard (2-hexanone) are measured and recorded. Peak areas for ethylbenzene, p/mxylene, o-xylene, the C9 and heavier aromatics, and internal standard are measured and recorded from the second analysis. The backflush peak eluting from the WCOT column in the second analysis contains only C9 and heavier aromatics. 4.4 The flame ionization detector response, proportional to the concentration of each component, is used to calculate the amount of aromatics that are present with reference to the internal standard.
5. Significance and Use 5.1 Regulations limiting the concentration of benzene and the total aromatic content of finished gasoline have been established for 1995 and beyond in order to reduce the ozone reactivity and toxicity of automotive evaporative and exhaust emissions. Test methods to determine benzene and the aromatic content of gasoline are necessary to assess product quality and to meet new fuel regulations. 5.2 This test method can be used for gasolines that contain oxygenates (alcohols and ethers) as additives. It has been determined that the common oxygenates found in finished gasoline do not interfere with the analysis of benzene and other aromatics by this test method. 6. Apparatus
6.1 Chromatographic System--See Practice E 355 for specific designations and definitions. Refer to Fig. 1 for a diagram of the system. 6. I. 1 Gas Chromatograph (GC), capable of operating at the conditions given in Table 1, and having a column switching and backfiushing system equivalent to Fig. I. Carrier gas pressure and flow control devices shall be capable 923
(@) D 5580 Valve on (Backflush)
Valve off (Reset) Capdlary Inlet
Capillary Inlet
TCEP Precolumn
TCEP Precolumn
Capill~w~u mr
) | 54
Secondary~ Flow
-
I
A (FID)
A (FID) Flow
FIG. 1
Vent or Detector B (TCD)
Valve Diagram, Aromatics in Gasoline
the carrier gas used must be 99.95 mol %. Additional purification may be necessary to remove trace amounts of oxygen.
chromatographic efficiency and selectivity in accordance with 6.3.1.1 can be used. 6.3. I. 1 TCEP Micro-Packed Column, 560-mm (22-in.) by 1.6-mm (%6-in.) outside diameter by 0.38-mm (0.015-in.) inside diameter stainless steel tube packed with 0.14 to 0.15 g of 20 % (mass/mass) TCEP on 80/100 mesh Chromosorb P(AW). This column was used in the cooperative study to provide the precision and bias data referred to in Section 15. 6.3.2 Nonpolar (Analytical) Column--Any column with equivalent or better chromatographic efficiency and selectivity in accordance with 6.3.2.1 can be used. 6.3.2.1 WCOT Methfl Silicone Cohonn, 30 m long by 0.53-mm inside diameter fused silica WCOT column with a 5.0-~tm film thickness of cross-linked methyl siloxane.
NOTE I: WarningmHelium is usually supplied as a compressed gas under high pressure. 7.2 Methylene Chloride--Used for column preparation. Reagent grade, free of nonvolatile residue. NOTE 2: Warning--Harmful when ingested or inhaled at high cencentrations. 7.3 2,2, 4- Trimethylpentane (isooctane)--Used as a solvent in the preparation of the calibration mixture. Reagent grade. NOTE 3: Warning--lsooctane is flammable and can be harmful or fatal when ingested or inhaled.
7. Reagents and Materials
7.1 Carrier Gas, appropriate to the type of detector used. Helium has been used successfully. The minimum purity of
1
7.4 Standards for Calibration and Identification, required for all components to be analyzed and the internal standard. Standards are used for establishing identification by retention time as well as calibration for quantitative measurements. These materials shall be of known purity and free of the other components to be analyzed.
Typical Chromatographic Operating Parameters Temperatures
Injection port (spht injector) FID (Detector A) TCD (Detector B) Nonpolar WCOT capillary InJtial Program rate Final
2000C 2500C 2000C
Polar TCEP precolumn (temperature to rema=n constant before t=me to BACKFLUSH, T1 or T2. Do not exceed maximum operating temperature.) Valve
NOTE 4: Warning--These materials are flammable and may be harmful or fatal when ingested or inhaled.
60"C (6 ram) 2*C/mfn 1150C (hold until all components elute) 600C or same as nonpolar WCOT capillary if TCEP/WCOT columns contained in ident=cal heated zone.
8. Preparation of Columns 8. I TCEP Column Packing." 8.1.1 Use any satisfactory method, that will produce a column capable of retaining aromatics from nonaromatic components of the same boiling point range in a gasoline sample. The following procedure has been used successfully. 8.1.2 Completely dissolve 10 g of TCEP in 100 mL of methylene chloride. Next add 40 g of 80/100 mesh Chromosorb P(AW) to the TCEP solution. Quickly transfer this mixture to a drying dish, in a fume hood, without scraping any of the residual packing from the sides of the container. Constantly, but gently, stir the packing until all of the solvent has evaporated. This column packing can be used immediately to prepare the TCEP column. 8.2 Micro-packed TCEP Column:
>115°C or same as nonpolar WCOT capdlary if valve and WCOT column contained in identical heated zone.
Flows and Conditions
Carrier gas Flow to TCEP precolumn (spilt rejector) Flow to WCOT capillary (auxiliary flow) Flow from split vent Detector gases Split ratio Sample size
~
¢ Vent or Detector B (TCD)
TABLE
C
Seconde
helium 10 mL/min 10 mL/min 100 mL/min as necessary 11 : 1 1 pL
924
( ~ D 5580 8.2.1 Wash a straight 560-mm (22-in.) lcngth of 1.6-mm (tA6-in.) outside diameter, 0.38-mm (0.015-in.) inside diameter stainless steel tubing with methanol and dry with compressed nitrogen. 8.2.2 Insert 6 to 12 strands of silvered wire, a small mesh screen or stainless steel frit inside one end of the tube. Slowly add 0.14 to 0.15 g of packing material to the column and gently vibrate to settle the packing inside the column. Insert silvered wire, mesh screen, or frit to the other end of the tube to prevent the packing material from falling. When strands of wire are used to retain the packing material inside the column, leave 6.0 mm (0.25 in.) of space at the top of the column. 8.3 WCOT Methyl Silicone Column--It is suggested that this column be purchased directly from a suitable capillary column manufacturer (see 6.3.2. I).
(first analysis) and ethylbenzene from the xylenes (second analysis). 11.3 Flow Rate (Carrier Gas) Adjustments: 11.3.1 Attach a flow measuring device to the precolumn vent (or Detector B) with the valve in the RESET or forward flow position and adjust the pressure of the capillary injection port (Fig. 1) to give 10.0-mL/min flow (17 to 20 psi). Soap bubble flow meters are suitable. This represents the flow through the polar precolumn. 11.3.2 Attach a flow measuring device to the split injector vent and adjust the flow from the split vent using the flow controller to provide a flow of 100 mL/min. Recheck the column vent flow set in 11.3.1 and adjust, if necessary. The split ratio should be approximately 11: I. 11.3.3 Switch the valve to BACKFLUSH position and adjust the variable restrictor to give the same precolumn vent flow set in 11.3.1. This is necessary to minimize flow changes when the valve is switched. 11.3.4 Switch the valve to the RESET position and adjust the auxiliary flow controller to give a flow of 10 mL/min at the Detector A (FID) exit. 11.4 Detector Setup---Depending on the particular type of instrumentation used, adjust the hydrogen, air, and makeup flows to the flame ionization detector and ignite the flame. If a thermal conductivity detector (Detector B) is being used to monitor the vent effluent in the valve RESET position, set the reference flow and turn on the detector circuit. 11.5 Valve Backflush and Reset Times: 11.5.1 The time to BACKFLUSH and RESET the valve will vary slightly for each column system and must be determined as described in 11.5.1.1, 11.5.1.2, and 11.5.1.3. The start time of the integrator or computer system and valve timer must be synchronized with the injection to accurately reproduce the backflush time. This procedure assumes that a thermal conductivity detector is installed on the precolumn vent line as Detector B (see 6.1.4.1). If a detector is not available, the appropriate valve BACKFLUSH times, T I and T2, must be determined experimentally. If the BACKFLUSH times, T I and T2, are not set correctly (switched too late), it is possible that part of the benzene and ethylbenzene peaks will be vented. 11.5.1.1 Adjust the valve to RESET (forward flow) and inject 1.0 pL of a blend containing approximately 5 % each of benzene, ethylbenzene, o-xylene, and 2-hexanone in isooctane. This mixture is used to set the valve timing, therefore, the exact concentration need not be known. Alternatively, the calibration mixture can be used for this test. Determine retention time in seconds at which benzene and ethylbenzene start to elute as measured by Detector B. Subtract 6 s from each of these and call these times to BACKFLUSH, TI and T2, respectively. The correct time for TI and T2 is just prior to the elution of benzene and ethylbenzene from the TCEP precolumn.
9. Column Conditioning 9.1 Both the TCEP and WCOT columns are to be briefly conditioned before use. Connect the columns to the valve (see Fig. 1 and 11.1) in the chromatographic oven. Adjust the carrier gas flows in accordance with 11.3 and place the valve in the RESET position. After several minutes, increase the column oven temperature to 120°C and maintain these conditions for 20 min. Cool the columns below 60"C before shutting off the carrier gas. 10. Sampling 10.1 Every effort should be made to ensure that the sample is representative of the fuel source from which it is taken. Follow the recommendations of Practice D 4057, or its equivalent, when obtaining samples from bulk storage or pipelines. 10.2 Appropriate steps should be taken to minimize the loss of light hydrocarbons from the gasoline sample to be analyzed. Upon receipt in the laboratory, chill the sample in its original container from 0 to 5"C (32 to 40*F) before and after sub-sampling is performed. 10.3 If necessary, transfer the chilled sample to a vaportight container and store at 0 to 5"C (32 to 40°F) until needed for analysis. 11. Preparation of Apparatus and Establishment of Conditions 11.1 AssemblynConnect the TCEP and WCOT column to the valve system (Fig. 1) using low-volume connectors and narrow bore tubing. It is important to minimize the volume of the chromatographic system that comes in contact with the sample, otherwise peak broadening will occur. 11.2 Initial Operating Conditions--Adjust the operating conditions to those listed in Table 1, but do not turn on the detector circuits. Check the system for leaks before proceeding further. 11.2.1 If different polar and nonpotar columns are used, or WCOT capillary columns of smaller inner diameter or different film thickness, or both, are used, it may be necessary to use different optimum flows and temperatures. 11.2.2 Conditions listed in Table 1 are applicable to the columns described in 6.3. If a WCOT column of a different film thickness is used, the conditions chosen for the analysis must sufficiently separate toluene from the internal standard
NOTE 5--Figure 2 is an example chromatogram illustrating the elution of a calibration mixture from the polar precolumn using the procedure described in 11.5.1.1. Times to BACKFLUSH, TI and T2, are indicated on the chromatogram. The times to BACKFLUSH, TI and T2, should be optimized for each chromatographic system. 11.5.1.2 Reinject the calibration blend and turn the valve to BACKFLUSH at time TI. When the internal standard peak (2-hexanone) returns to baseline switch valve back to 925
(i~ D 5580
2000.
iso-octane
Detector B (TCD)
1~00.
toluene
1000.
C8 aromatics
2-hexenone
~$00.
O.
•
-
-
,
1
0
FIG. 2
.
.
.
.
i
.
.
2
.
.
=
.
.
.
.
3
,
i
4
[5
Determination of Precolumn Backflush Times, T1 and T2
RESET (forward flow) position. Call this time T3. 11.5.1.3 Reinject the calibration blend and BACKFLUSH at time T2. When the o-xylene peak returns to baseline, switch the valve back to RESET (forward flow). Call this time T4. 11.6 Polar Precolumn Selectivity Check: 11.6.1 The selectivity of the polar precolumn is critical to allow for accurate determination of the C9 and heavier aromatics without non-aromatic interferences. The selectivity must be verified so that for the second analysis, when the time to BACKFLUSH T2 is properly adjusted, all of the Ciz and lighter non-aromatic hydrocarbons are vented from the polar precolumn while the heavier aromatics are retained. The following test can be used to verify the precolumn performance. 11.6.1.1 Prepare a blend containing approximately 1.5 % n-dodecane in 2,2,4-trimethylpentane (isooctane). nDodecane is used to represent the high boiling non-aromatic hydrocarbons in gasoline. Inject 1.0 IxL of the mixture under the conditions specified in 11.2 to 11.5 and actuate the valve at time T2 (BACKFLUSH) and time T4 (RESET). Record the signals from both the flame ionization (Detector A) and thermal conductivity (Detector B) detectors. Verify that n-dodecane fully elutes from the polar precolumn before BACKFLUSH time T2. When monitoring the thermal conductivity detector (Detector B), the n-dodecane peak should return to baseline before BACKFLUSH time T2. If not, part of the n-dodecane peak will be backflushed to the non-polar WCOT column and be detected by the flame ionization detector after the valve RESET time T4. If a thermal conductivity detector is not available on the precolumn vent line, the chromatogram obtained by the flame ionization detector can be used to verify that all the n-dodecane is being vented. This chromatogram should not show any significant response from n-dodecane after the RESET time T4. 11.6.1.2 If all of the n-dodecane peak is not completely vented from the polar precolumn, as measured by the
thermal conductivity or flame ionization detector, recheck instrument parameters and valve backflush times (11.5) or replace the polar precolumn. If the valve is contained in a separate isothermal heated zone, it may be necessary to use a higher temperature to prevent absorption of small amounts of n-dodecane on the rotor or transfer tubing surfaces. ! 2. Calibration
12.1 Preparation of Calibration Samples--Prepare multicomponent calibration standards of benzene, toluene, ethylbenzene, o-xylene, and 1,2,4-trimethylbenzene at concentrations of interest by mass in accordance with Practice D 4307. O-xylene is ~ to represent the xylenes while 1,2,4-trimethylbenzene is used for the C9 and heavier aromatics. For each aromatic component, use at least five calibration points and ensure that the concentration of each aromatic component is within its calibration range. For benzene, calibration concentrations of 0.1, 0.5, 1.0, 2.0, and 5 volume percent can be used. For toluene: 1.0, 2.5, 5.0, 10.0, and 15.0 volume %. For ethylbenzene, o-xylene, and 1,2,4-trimethylbenzene: 0.5, 1.0, 2.5, 5.0, and 10 volume % can be used. The relative densities listed in Table 2 shall be used as a guide in determining the proper mass of aromatic components that need to be added in order to arrive at a TABLE 2 Component Benzene Toluene Ethylbenzene p/ m-Xylene o-Xylene 1,2,4-Trimethylbanzene C9 plus aromatics 2-hexanone
Physical Constants Relative Density (15.56/15.56°C)A 0.8845 0.8719 0.8717 0.8679 0.8848 0,8806 0,8764 0.8162
A "Physical Constants of Hydrocarbons C1-Clo," STP 109A, ASTM, 1916 Race St., Philadelphia, PA 19103. The mixed xylene (p/m-xylene) density based upon a 1:3 ratio of p-xylene to m-xylene. Cg plus aromatics based upon the average relative density values of the 30 C9-Clo aromatics.
926
~) D 5580 TABLE 3
Benzene
~ 1.0 2.0 3.0 4.0 5.0
/ /
0.80
+ /
0
0.70 a$
0.60 h
0.50
0.30
/
0.20
~÷ O.lO
/
+
/
~
x2
y2
2.0 0.5 0.0 0.5 2.0
4.0 1.0 0.0 1.0 4.0
1,0 0.25 0.0 0.25 1.0
1.5 25.0 I0.0
~y2
= 2.5
r2
(~, x. y)2 (~ x2).(~ ~)
r2
25.0 (10.0)(2.5)
1.0
+
in accordance with the procedure in 12.4. Measure the peak areas of benzene, toluene, and internal standard peaks from the first analysis. From the second analysis measure the peak areas of internal standard, ethylbenzene, o-xylene, and 1,2,4-trimethylbenzene. Determine the response ratio (rsp,) and amount ratio (amt,) for each component in each standard using Eqs 2 and 3. rsp i = (Ai/As) (2)
rsp r a t i o = 1.41(amt ratio) + 0.00181 r ^ 2 = 1.000
+
0.00 0.000
1.0 -0.5 0.0 0.5 1,0
=3
• x2
0.40 /
y=~-~
-2.0 -1.0 0.0 1.0 2.0
0.5 1.0 1.5 2.0 2,5 = = =
(~ xy) 2
ExampleofDataSetforr2Calculation A x=~-£
0500
o.~oo
o.loo
amt ratio FIG. 3
where:
Typical Benzene Calibration Curve
A i = area of aromatic component, and A s = area of internal standard.
target volume percent concentration. 12.2 Before preparing the standards, determine the purity of the aromatics by capillary GC and make corrections for the impurities found. Whenever possible, use stocks of at least 99.9 % purity. 12.3 Prepare standards by transferring a fixed volume of aromatic component using pipettes, eye droppers, or syringes to 100-mL volumetric flasks or 100-mL septum-capped vials as follows. Cap and record the tare weight of the volumetric flask or vial to 0.1 rag. Remove the cap and carefully add the aromatic components to the flask or vial starting with the least volatile (1,2,4-trimethylbenzene). Cap the flask and record the net mass (Wi) of the aromatic component added to 0.1 mg. Repeat the addition and weighing procedure for each aromatic component. Do not exceed 50 volume % for all aromatics added. Similarly, add 10 m L of the internal standard, 2-hexanone, and record its net mass (Ws) to 0.1 mg. Dilute each standard to the mark with aromatics free 2,2,4-trimethylpentane (isooctane). Store the capped calibration standards in a refrigerator at 0 to 5"C (32 to 40*F) when not in use. 12.4 Calibration P r o c e d u r e m W i t h the valve initially in the RESET mode, chromatograph each of the calibration mixtures (12.1) twice using valve timing procedures in accordance with 11.5. For the first analysis use times T I (BACKFLUSH) and T3 (RESET) to actuate the valve. For the second analysis use times T2 (BACKFLUSH) and T4 (RESET) to actuate the valve.
amt, = ( W i / H ~ )
where: W i = mass of aromatic component, and W s = mass of internal standard. 12.4.1.1 Prepare a calibration curve for each aromatic component by plotting the response ratios (rsp~), as the y-axis, versus the amount ratios (amt,), as the x-axis. Figure 3 is an example of such a plot. 12.4.1.2 Calculate the correlation coefficient r 2 value for each aromatic component in the calibration using Eq 4. The r 2 value should be at least 0.990 or greater. If the above criteria for r 2 is not met, rerun the calibration or check instrument parameters and hardware. r2 =
(~ xy) 2
(4)
(Z x2)(~ j,2) where: x = xi - x y = Yi - .~
(5) (6)
and: X, = a m t ratio data point,
= average values for all amti data points, ]I,. = corresponding rspi ratio data point, and = average values for all rsp~ data points. 12.4.1.3 Table 3 gives an example on the calculation o f r 2 for an ideal data set. 12.4.2 L i n e a r L e a s t S q u a r e F i t - - F o r each aromatic i calibration data set, obtain the linear least square fit equation in the form:
NOTE 6--The first analysis is used to calibrate the gas chromatograph for benzene and toluene. The second analysis is used to calibrate for ethylbenzene, the xylenes (o-xylene), and the C9 and heavier aromatics ( 1,2,4-trimethylbenzene).
12.4.1 L i n e a r i t y T e s t ~ A n a l y z e
(3)
(rspi) = (mi)(amt ,) + b I
the calibration standards
where: 927
(7)
I ~ D 5580 TABLE 4
rsPi ---- response ratio for aromatic i (y-axis),
m;
= slope of linear equation for aromatic i, amti -- a m o u n t ratio for aromatic i (x-axis), and bi = y-axis intercept. 12.4.2.1 The values m i and b i are calculated as follows:
Component
m, = ~ xy/rZ x ~
(8)
b, = ~ - m?7
(9)
Benzene Toluene Ethylbenzene P/M-xylene O-xylene C9 plus aromatics Total aromatics
and: 12.4.2.2 For the example in Table 3
TABLE 5
m, = 5/10 = 0.5
Repeatability Estimates for Aromatics in Gasoline
1.5 - (0.5)(3)
=
0
Benzene Toluene Ethylbenzene P/M-xylene O-xylene C9 plus aromatics Total aromatics
(l 1)
12.4.2.3 Therefore, the least square equation (7) for the example in Table 3 is: (12)
(rsp,) = 0.5(amt,) + 0
NOTE 7--Normally the b, value is not zero and can be positive or negative. Figure 3 gives an example of linear least square fit for benzene and the resulting equation in the Eq 7. 12.4.3 Y-Intercept T e s t - - F o r an o p t i m u m calibration, the absolute value of the y-intercept (b,) must be at a m i n i m u m . In this case, Ai approaches zero when w, is less than 0.1 mass %. In practice, this means the mass % (w,) calculated for an aromatic with zero peak area must be close to zero. The equation to determine the mass % aromatic i, or w,, reduces to Eq 13. The y-intercept can be tested using 13 below: w,
=
(b,/m,)( Ws/Wg)100 %
(13)
where: wi = mass % aromatic i, Ws = mass of internal standard added, g, and Wg = mass of gasoline samples, g.
0.0265 (Xo-ss) 0.0301 (X°.s) 0.029 0,071 0.0296 (Xo 5) 0.0145 (X+5,157) 0.46
R a n g~,) e, (mass
Reproducibility (X = mass %)
0.14-1.79 2.11-10.08 0.57-2.65 2.06-9.59 0.77-3.92 8.32-25.05 16.34-49.07
0.1229 (X° es) 0.0926 (X° s) 0.163 0.452 0.1168 (X°.s) 0.070 (X+5.157) 1.59
values exceed the mass % limit, rerun the calibration procedure for aromatic i, or check instrument parameters and hardware. The following gives an example o f the calculation for the y-intercept (b,) test using the data from Fig. 3 for aromatic i (benzene) for which b, = 0.0018 and m, = 1.41. From 13.1, a typical sample preparation may contain approximately Ws = 0.8 g(1.0 mL) of internal standard and Wg = 6.75 g (9.0 mL) of a gasoline sample. Substituting these values into Eq 13 yields: w, = (0.0018/1.41)(0.8/6.75)100 % w, = 0.01 mass %
For benzene, w, must be less than 0.02 mass %. For the other aromatics, w, must be less than 0.2 mass %. If any of the w,
13. Procedure 13.1 Preparation o f S a m p l e - - T r a n s f e r 1 m L o f internal 2
3
4
I.
1. benzene 2. toluene 3.2-hexsnone (ISTD) 4. backflush peek (C8 plus aromatics and C9 plus non-aromatic hydrocarbons)
iiii 1
1.0~e
o
i
o
• c5
FIG. 4
A .
, 10
(14)
Since w, is less than 0.02 mass %, the y-intercept (b,) has an acceptable value for benzene. Similarly, determine w, for all other aromatics.
NOTE 8mSince in practice Ws and Wg vary slightly from sample to sample, use an average value as indicated below.
6"Oe
0.14-1.79 2.11-10.08 0.57-2.65 2.06-9.59 0.77-3.92 8.32-25,05 16.34-49.07
Reproducibility Estimates for Aromatics in Gasoline
Component =
Repeatability (X = mass %)
(10)
and b,
R a n g~,) e, (mass
. . . .
, 18
. . . .
i, ~O
Aromatics in Gasoline, Analysis No. 1
928
-
-
~
1. 2. 3. 4. 5.
D 5580
2-hexanone (ISTD)
ethylbanzene p/m.xylene o-xylene C 9 plus aromatics
-,A..0 e a
3.0e~
2.0
ew'~
1 .oe(~
T2 o o
1
T4
_1 ~.'0
~o
~o
~o
FIG. 5 Aromaticsin Gasoline,AnalysisNo. 2 standard (Ws) by a volumetric pipette into a tared and capped 10-mL volumetric flask or capped vial. Record the net mass of the internal standard added to the nearest 0.1 mg. Retare the capped flask or vial. Fill the volumetric flask or vial with 9 mL of chilled sample, cap, and record the net mass (Wg) of the sample added. Mix thoroughly. If using an automatic sampler then transfer an aliquot of the solution into a glass GC vial. Seal the GC vial with a TFEfluorocarbon-lined cap. If the sample is not immediately analyzed, store at 0 to 5°C (32 to 40°F). 13.2 Chromatographic Analysis--Introduce an aliquot of the sample, containing internal standard, into the gas chromatograph using the same technique and sample size as used for the calibration analysis. An injection volume of 1 gL with a 11:1 split ratio has been used successfully. Chromatograph the sample twice using valve timing procedures in accordance with 11.5. Use times T1 and T3 for the first analysis to BACKFLUSH and RESET the valve. Use times T2 and T4 for the second analysis. t3.3 Interpretation of Chromatogram--Compare the retention times of sample components to those of the calibration analysis to determine the identities of the aromatics. Identify benzene, toluene, and the internal standard from the first analysis. Identify the internal standard, ethylbenzene, p/m-xylene, o-xylene, C9 and heavier aromatic composite from the second analysis. Refer to Figs. 4 and 5 for sample chromatograms.
where: Wi = mass of aromatic component i, Ai -- area of aromatic component i, As = area of internal standard, and Ws = mass of internal standard added. 14.1.1 To obtain mass percent (w;) results for each component:
wi(100) wg
w, = ~
(I 6)
where: Wg = mass of gasoline sample. 14.1.2 Report the mass percent (w,) results of the following aromatics to the nearest 0.10 %; benzene, toluene, ethylbenzene, p/m-xylene, o-xylene, C9 and heavier aromatics. 14.1.3 To obtain the total mass percent aromatics, sum the mass percent (w,) results of all the individual aromatic components i. 14.2 Volumetric Concentration of Aromatic Components--If the volumetric concentration of each aromatic component i is desired, calculate the volumetric concentration in accordance with Eq 15:
,,7,
14. Calculation and Report 14.1 Mass Concentration of Aromatics--After identifying the peaks, measure the areas of benzene, toluene, and the internal standard from the first analysis and the internal standard, ethylbenzene, p/m-xylene, o-xylene, C9 and heavier aromatics from the second analysis. Using the slope and y-intercept of the least square fit calibrations in 12.4.2, calculate the mass of each aromatic component (Wi) in the gasoline samples using the response ratio (rsPi) of the areas of the aromatic component to the internal standard as follows:
where: v, = volume percent of each aromatic component to be determined, Dj -- relative density of the fuel under study as determined in accordance with Practice D 1298 or Test Method D 4052, and D, = relative density at 15.56°C (60°F) of the individual aromatics (Table 2).
929
t~ D 5580 apparatus under constant operating conditions on identical test materials would, in the long run, in the normal and correct operation of the test method exceed the following values in only one case in twenty. See Table 4. 15.1.2 Reproducibility--The difference between two single and independent results obtained by different operators working in different laboratories on identical material, would in the long run, exceed the following values in one case in twenty. See Table 5. 15.1.3 Bias--Since there is no accepted reference material suitable for determining bias for the procedure in this test method, no statement of bias is being made.
14.2.1 Report the volume percent results (Vl) of the following aromatic components to the nearest 0.01%; benzene, toluene, ethylbenzene, p/m-xylene, o-xylene, and C9 and heavier aromatics. 14.2.2 To obtain total volume percent aromatics, sum the volume percent (v,) results of all the individual aromatic components i. 15. Precision and Bias s 15.1 Precision--The precision of this test method as determined by the statistical examination of the interlaboratory test reports is as follows: 5 15.1.1 Repeatability--The difference between successive test results obtained by the same operator with the same 5 Supporting data are available from ASTM headquarters. D02-1329.
16. Keywords 16.1 aromatics; benzene; ethylbenzene; gas chromatography; gasoline; toluene; xylenes
Request RR:
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted m connection with any item mentioned in this standard Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility This standard is sublect to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Herbor Drive, West Conshohocken, PA 19428,
930
4~1~ Designation: D 5599 - 95
Standard Test Method for Determination of Oxygenates in Gasoline by Gas Chromatography and Oxygen Selective Flame Ionization Detection This standard is issued under the fixed designation D 5599; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
E 594 Practice for Testing Flame Ionization Detectors Used in Gas Chromatography 4 E 1064 Test Method for Water in Organic Liquids by Coulometric Karl Fischer Titration 5 E 15 l0 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs 4
1. Scope 1.1 This test method covers a gas chromatographic procedure for the quantitative determination of organic oxygenated compounds in gasoline having a final boiling point not greater than 220"C and oxygenates having a boiling point limit of 130"C. It is applicable when oxygenates are present in the 0. l to 20 % by mass range. 1.2 This test method is intended to determine the mass concentration of each oxygenate compound present in a gasoline. This requires knowledge of the identity of each oxygenate being determined (for calibration purposes). However, the oxygen-selective detector used in this test method exhibits a response that is proportional to the mass of o.~:vgen. It is, therefore, possible to determine the mass concentration of oxygen contributed by any oxygenate compound in the sample, whether or not it is identified. Total oxygen content in a gasoline may be determined from the summation of the accurately determined individual oxygenated compounds. The summed area of other, uncalibrated or unknown oxygenated compounds present, may be converted to a mass concentration of oxygen and summed with the oxygen concentration of the known oxygenated compounds. 1.3 The values stated in SI units are to be regarded as the standard. 1.4 This standard does not purport to address all of the
3. Terminology
3.1 Definitions: 3.1.1 independent reference standardsqcalibration samples of the oxygenates which are purchased or prepared from materials independent of the quality control check standards and used for intralaboratory accuracy. 3.1.2 oxygenate, n - - a n oxygen-containing compound, such as an alcohol or ether, which may be used as a fuel or fuel supplement. D 4175 3.1.3 quality control check standards--calibration samples of the oxygenates for intralaboratory repeatability. 4. Summary of Test Method 4.1 An internal standard of a noninterfering oxygenate, for example, 1,2-dimethoxyethane (ethylene glycol dimethyl ether) is added in quantitative proportion to the gasoline sample. A representative aliquot of the sample and internal standard is injected into a gas chromatograph equipped with a capillary column operated to ensure separation of the oxygenates. Hydrocarbons and oxygenates are eluted from the column, but only oxygenates are detected with the oxygen-selective flame ionization detector (OFID). A discussion of this detector is presented in Section 6. 4.2 Calibration mixtures are used for determining the retention times and relative mass response factors of the oxygenates of interest. Suggested calibrant materials are listed in 8.2. 4.3 The peak area of each oxygenate in the gasoline is measured relative to the peak area of the internal standard, A quadratic least-squares fit of the calibrated data of each oxygenate is applied and the concentration of each oxygenate calculated.
saJL,ty concerns, if any. associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. Referenced Documents
2.1 ASTM Standards: D 1744 Test Method for Water in Liquid Petroleum Products by Karl Fischer Reagent 2 D4175 Terminology Relating to Petroleum, Petroleum Products, and Lubricants 3 D 4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards 3 D 4626 Practice for Calculation of Gas Chromatographic Response Factors 3
NOTE l - - W h i l e
1,2-dimethoxyethane has been found to be an
appropriate internal standard, other oxygenatesmay be used provided they are not present in the sample and do not interfere with any compound of interest.
5. Significance and Use 5.1 In gasoline blending, the determination of organic
This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02,04.0L on Gas Chromatography. Current edition approved Sept. 10, 1995. Published November 1995. Originally published as D 5599 - 94. Last previous edition D 5599 - 94. 2 ,,Innual BtuJk ofASTM Standard~', Vol 05.01. 3 Annual Book of ASTM Standards, Vol 05.02.
4 Annual Book ~fASTM Standards, Vol 14.02. 5 Annual Book of ASTM Standards° Vol 15.05.
931
t~
O 5599
analyzed before the catalyst needs replacement.
oxygenated compounds is important. Alcohols, ethers, and other oxygenates are added to gasoline to increase the octane number and to reduce tailpipe emissions of carbon monoxide. They must be added in the proper concentration and ratios to meet regulatory limitations and to avoid phase separation and problems with engine performance or efficiency. 5.2 This test method provides sufficient oxygen-to-hydrocarbon selectivity and sensitivity to allow determination of oxygenates in gasoline samples without interference from the bulk hydrocarbon matrix.
7. Apparatus
6. Theory of OFID Operation 6.1 The detection system selective for organic oxygen consists of a cracking reactor, hydrogenating reactor (methanizer), and a flame ionization detector (FID). The cracking reactor, connected immediately after the gas chromatographic capillary column, consists of a Pt/Rh capillary tube. Carbon monoxide (CO) is formed from compounds containing oxygen according to the following reaction: CxHyOz --* zCO + (y/2)H 2 + (x - z)C (1) 6.2 An excess layer of carbon is created in the Pt/Rh tube of the cracking reactor from the introduction of hydrocarbons from the sample or, if so designed, from a hydrocarbon (for example, pentane or hexane) doping system, or both. This layer of carbon facilitates the cracking reaction and suppresses hydrocarbon response. 6.3 The carbon monoxide formed in the cracking reactor is converted to methane in the hydrogenating reactor according to the following reaction: CO + 3H 2 --, CH4 + H20
(2)
The CH 4 is subsequently detected with an FID. 6.4 The methanizer consists either of a short porous layer open tubular (PLOT) glass capillary tube internally coated with aluminum oxide with adsorbed nickel catalyst or stainless steel tubing containing a nickel-based catalyst. It is installed within or before the FID and is operated in the range from 350 to 450*C, depending on the instrument's manufacturer. NOTE 2--Gasolines with high sulfur content may cause a loss in detector sensitivitythereby hmiting the number of samples that can be
~
Carrier gas
7.1 Gas Chromatograph--Any gas chromatograph can be used having the following performance characteristics: 7. I . l Cohtmn Temperature Programmer--The chromatograph must be capable of reproducible linear temperature programming over a range sufficient for separation of the components of interest. 7.1.2 Sample Introduction System--Any system capable of introducing a representative 0.1 to 1.0-1aL liquid sample into the split inlet device of the gas chromatograph. Microlitre syringes, autosamplers, and liquid sampling valves have been used successfully. The split injector should be capable of accurate split control in the range from 10:l to 500:1. 7.1.3 Carrier and Detector Gas Control--Constant flow control of carrier and detector gases is critical to optimum and consistent analytical performance. Control is best provided by the use of pressure regulators and fixed flow restrictors. The gas flow rates are measured by any appropriate means. The supply pressure of the gas delivered to the gas chromatograph must be at least 70 kPa (l 0 psig) greater than the regulated gas at the instrument to compensate for the system back pressure. In general, a supply pressure of 550 kPa (80 psig) will be satisfactory. 7.2 OFID Detector System, consisting of a cracking reactor, methanizer, and FID. A schematic of a typical OFID system is shown in Fig. I. 7.2.1 The detector must meet or exceed the typical specifications given in Table l of Practice E 594 while operating in the normal FID mode as specified by the manufacturer. 7.2.2 In the OFID mode, the detector shall meet or exceed the following specifications: (a) equal to or greater than l03 linearity, (b) less than 100-ppm mass oxygen (l-ng O/s) sensitivity, (c) greater than l06 selectivity for oxygen compounds over hydrocarbons, (d) no interference from coeluting compounds when 0. I to 1.0-1xL sample is injected, (e) equimolar response for oxygen. 7.3 Column--A 60-m by 0.25-mm inside diameter fused silica open tubular column containing a 1.0-1xm film thickness of bonded methyl silicone liquid phase is used. Equiva-
SampleCn HmOx Crackirrg reactor
Methanizer
FID
1300"(
Pt/n_.__hh
~
meter
-0 L (H2) Air
Capillarycolumn •
4
If designed FIG. 1 Schematicof an OFID
932
H2
~ TABLE 1
D 5599 all other oxygenates present (for example, 1,2-dimethoxyethane). 8.4 Dopant--If the OFID is so designed, reagent-grade pentane is used as a hydrocarbon dopant for the cracking reactor.
Typical Operating Conditions
Temperatures, °C Injector Column Detector Methantzer Reactor
250 50°C (hold 10 rain), ramp 8°/rain to 250°C 350-450 850-1300
NOT~ 4: Warning--Pentane is extremely flammable and harmful when inhaled.
Flows, mL/mln Column carrier gas Detector gases Auxlhary (for dopant, if available)
1 Atr: 300 H2 30 H2:0 6
Sample Stze Spht Ratio
0.1-1.0 p.LA 100-1
8.5 Instrument GaseswThe gases supplied to the gas chromatograph and detector arc: 8.5.1 Air, zero grade. NOTE 5: Warning--Compressedair is a gas under high pressure and supports combustion. 8.5.2 Hydrogen, pure grade, 99.9 mol %.
A Sample size and split ratio must be adjusted so that the oxygenates in the range from 0.1 to 20.0 mass • are eluted from the column and measured linearly at the detector. Each laboratory must establish and monttor the conditions that are needed to maintain linearity with their individual instruments. Nonlinearity is most commonly observed when using an OFID with samples containing high levels of individual oxygenates and can be compensated for by either decreasing the sample size, increasing the split ratio, or diluting the sample with an oxygenatefree gasoline. A sample size of 0.5 p.L and a split ratio of 100:1 has been used successfully in most cases.
NOTE 6: Warning--Hydrogen is an extremely flammable gas under high pressure.
8.5.3 Helium or nitrogen as column carder gas, 99.995 mol % minimum purity, or a blend of 95 % helium/5 % hydrogen, depending on the instrument's manufacturer. NOT~ 7: Warning--Helium and nitrogen are compressed gases under high pressure.
lent columns which provide separation of all oxygenates of interest may be used. 7.4 Integrator~Use of an electronic integrating device or computer is required. The device and software should have the following capabilities: 7.4.1 Graphic presentation of the chromatogram, 7.4.2 Digital display of chromatographic peak areas, 7.4.3 Identification of peaks by retention time, 7.4.4 Calculation and use of response factors, and 7.4.5 Internal standard calculation and data presentation.
8.5.4 Additional purification of the carder, air, and hydrogen is recommended. Use molecular sieves, Drierite, charcoal, or other suitable agents to remove water, oxygen, and hydrocarbons from the gases. 8.6 Sample Container--Glass vials with crimp on or screwdown sealing caps with self-sealing polytetrafluoroethylene (PTFE)-faced rubber membranes are used to prepare calibration standards and samples for analyses.
9. Preparation of Apparatus 9.1 Chromatograph and OFID--Place instrument and detector into operation in accordance with the manufacturer's instructions. Install the capillary column according to Practice E 1510. Adjust the operating conditions to provide for separation of all oxygenates of interest. Typical conditions used with the column specified in 7.3 are listed in Table 1. 9.2 System Performance--At the beginning of each day of operation, inject an oxygenate-free gasoline sample into the chromatograph to ensure minimum hydrocarbon response. If hydrocarbon response is detected, the OFID is not operating effectively and must be optimized according to the manufacturer's instructions before the sample can be analyzed.
8. Reagents and Materials 8. l Purity of Reagents--Reagents grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available. 6 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 8.2 Calibrant MaterialswThe following compounds may be used for calibrating the detector: methanol, ethanol, n-propanol, iso-propanol, n-butanol, tert-butanol, secbutanol, iso-butanol, tert-pentanol, methyl lert-butylether (MTBE), tert-amylmethylether (TAME), ethyl tertbutylether (ETBE), di-iso-propylether (DIPE). NOTV 3: Warning--These materials are very flammable and may be harmful or fatal when ingested, inhaled, or allowed to be absorbed through the skin.
8.3 Internal Standard--Use one of the compounds listed in 8.2 that is not present in the sample. If all of the materials in 8.2 are likely to be present in the test sample, use another organic oxygenate of high-grade purity that is separated from 6 Reagolt ChemicaL~. Amerwan Chemical Society Spectllcattons, American Chemical Society, Washington, DC. For suggestionson the testing of reagents not hstcd by tile American Chemical Society, see Analar Stamlards/or Laboratory C'hemwal~, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia aml National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockvillc. MD.
933
10. Calibration and Standardization I O. 1 Retention Time Identification--Determine the retention time of each oxygenate component by injecting small amounts either separately or in known mixtures. Table 2 gives typical retention times for the oxygenates eluting from a 60-m methyl silicone column temperature programmed according to conditions given in Table 1. A chromatogram of a blend of oxygenates is given in Fig. 2. 10.2 Preparation of Calibration Samples--The calibration samples are prepared gravimetrically in accordance with Practice D4307 by blending known weights of organic oxygenate compounds (such as listed in 8.2) with a known weight internal standard and diluting to a known weight with an oxygenate-free gasoline. The calibration samples should contain the same oxygenates (in similar concentrations) as
~
D 5599 oxygenate to the nearest 0.1 mg. Repeat this process for any additional oxygenates of interest except the internal standard. Add oxygenate-free gasoline to dilute the oxygenates to the desired concentration. Record the mass of gasoline added to the nearest 0. l mg, and determine and label the standard according to the mass % quantities of each oxygenate added. These standards are not to exceed 20 mass % for any individual pure component due to potential hydrocarbon breakthrough or loss, or both, of calibration linearity. To minimize evaporation of light components, chill all chemicals and gasoline used to make standards. 10.2.2 Add a quantity of an internal standard (such as 1,2-dimethoxyethane) and reweigh the contents. Record the difference in masses as the mass of internal standard to the nearest 0.1 mg. The mass of the internal standard should be between 2 and 6 % of the mass of the calibration sample. 10.2.3 Ensure that the prepared standard is thoroughly mixed, and transfer approximately 2 mL of the solution to a vial compatible with the autosampler if such equipment is used. 10.2.4 At least five concentrations of each of the expected oxygenates should be prepared. The standards should be as equally spaced as possible within the range and may contain more than one oxygenate. A blank for zero concentration assessments must also be included before each standard. Additional standards should be prepared for other oxygenates of concern. 10.3 S t a n d a r d i z a t i o n - - R u n the calibration samples and establish the calibration curve for each oxygenate. The area under each peak in the resulting chromatogram is considered a quantitative measure of the corresponding compound. Using the peak area of each oxygenate and the internal standard, calculate the relative mass response factor for each oxygenate (relative to the internal standard) in accordance with Practice D 4626 and Eq 3:
E
,
¢
I 0.0
5.0
s ~
10.0 15.0 Time (minutes)
20.0
NOTE--Operating conditions ~n accordance with Table 1. FIG. 2
Chromatogram of an Oxygenates Blend
at:e expected in the sample under test. Before preparing the standards, determine the purity of the oxygenate stocks and make corrections for the impurities found. Whenever possible, use stocks of at least 99.9 % purity. Correct for the purity of the components for water content determined by Test Method D 1744 or Test Method E 1064. Quality control check standards may be prepared from the same oxygenate stocks and by the same analyst. Quality control check standards must be prepared from separate batches of the final diluted standards. 10.2.1 Tare a glass sample container and its PTFE-faced rubber septum sealing cap. Transfer a quantity of an oxygenate to the sample container and record the mass of the
RF~. = (WJA,)(A,/IV,)
where: RF~ = relative mass response factor of the test oxygen
compound, mass of the test oxygen compound in the calibration sample, g, w , = mass of the internal standard in the calibration sample, g, A s = peak area of the test oxygen compound in the calibration sample, and A i = peak area of the internal standard in the calibration sample. Since five concentrations of each expected oxygenate are used, calculate the response factors for all five concentration levels and take the averaged value as the relative mass response factor of the test oxygen compound. 10.3.1 Plot the response ratio (rsp,):
TABLE 2 Oxygenates Retention Times, Relative Response Factors, and Molecular Masses (Conditions as in Table 1) Compound D~ssolved Oxygen Water Methanol Ethanol Isopropanol tea-Butanol n-Propanol MTBE sec-Butanol DIPE Isobutanol ETBE tert-Pentanol 1,2-dJmethoxyethane n-Butanol TAME
Retent=on Time m=n
Molecular Mass
5.33 5.89 6.45 7.71 8.97 10.19 11.76 12.73 13.92 14,53 15.32 15.49 15.97 16.57 17.07 18.23
32.0 18.0 32.0 46.1 60.1 74 1 60.1 88.2 74,1 102.2 74.1 102.2 88.1 90.1 74.1 102.2
Ws
Relative Relative Response Response FactorsA.a Factorsa.C O D 0.70 0.99 1 28 1.63 1.30 1.90 1.59 2.26 1.64 2.25 2.03 1.00 1.69 2.26
(3)
D D 0.98 0.97 0.96 0.99 0.98 0.97 0.97 1.00 0,99 0.99 1,04 1.00 1.03 1.00
rsps = (As/A i)
(4)
as the y-axis versus amount ratio (amt~): amt~ = (Ws/Wi)
'~ Based on mass percent oxygenate compound basis. n Relattve to 1,2-dimethoxyethane. c Based on mass percent oxygen basis. o Not determined.
(5)
as the x-axis calibration curves for each oxygenate. Check the correlation ta value for each oxygenate calibration. The ra value should be at least 0.99 or better. 934
D 5599
~) TABLE 3
Precision Interval as Determined from Cooperative Study Data Repeatability
Component
Repeatability
Wt %
MeOH
0.20 0.50 1.00 2.00 3.00 4.00 500 6.00 10.00 12.00 14.00 16 00 20.00
0.03 0.05 0 07 0 10 0.12 0,13 0.15 0.17 0.22 0.24 . . . . . .
EtOH
iPA
tBA
0.01 0.02 0 02 0 03 0.03 0.04 0.06 0.06 0.06 0.07 0.11 0.08 0.13 0,09 0.16 0.10 0.25 0.14 0.29 0.15 . . . . . . . . . . . . . . . . . . . . . . . . . .
nPA
0.02 0.02 0.03 0 03 0.05 0.04 0.08 0.05 0.10 0.06 0,12 0,06 0.14 0.07 0.16 0.07 0.22 0.09 0.25 0.09 . . . . . . . . . . . .
MTBE
sBA
DIPE
IBA
ETBE
tAA
nBA
0.02 0.03 0.05 0,07 0.09 0.11 0.13 0.14 0.19 0.21 0.23 0.25 0.28
0.01 0 02 0.03 0.04 0.05 0.06 0.07 0.08 0,10 0.11 ... ... ...
0.02 0.03 0,05 0.08 0.10 0.12 0.14 0.16 0.22 0.25 0.28 0.30 0.35
0.01 0.02 0.03 0.05 0.07 0.09 0.11 0.12 0.18 0.21 ... .,. ...
0.01 0.01 0.04 0,07 0.10 0.13 0,16 0.19 0.29 0.34 0.39 0.43 0.53
0,03 0.03 0.04 0.04 0.05 0.06 0.07 0.08 0.08 0,10 0.09 0.11 0.10 0.13 0.10 0.14 0.13 0.17 0.14 0.19 . . . . . . . . . . . . . . . . . .
TAME 0.02 0.03 0.04 0.06 0,06 0.09 0.10 0.11 0.15 0.17 0.18 0.20 0.23
Total Oxygen ... 0.03 0.05 0.08 0.11 0.13 . .. ... . .. ... .. . .
Reproducibility Component Wt %
MeOH
EtOH
iPA
0.20 0.50 1.00 ZOO 3.00 4.00 5.00 6.00 10.00 1,2.00 14.00 16.00 20.00
0.06 0.14 0.25 0.45 0.64 0.82 1.00 1.17 1.81 2.12 . .
0.06 0.13 0.21 0.35 0.47 0.59 0.69 0.79 1.15 1.32 . . .
tBA
nPA
MTBE
sBA
DIPE
iBA
ETBE
tAA
0.05 0.11 0.20 0.28 0.48 0,61 0.72 0.84 1.26 1.46 . . .
0.04 0.09 0 17 0.31 0.45 0.58 0.70 0.82 1.29 1.51
0.02 0.05 0.10 0.19 0.28 0.37 0.46 0.55 0,89 1.06 1.23 1.39 1.72
0.05 0.10 0.17 0.28 0.38 0.47 0.55 0.63 0.91 1.04 ..• •,• • . .
0.05 0.10 0.16 0.26 0.35 0.43 0.50 0.57 0.82 0.93 1.04 1.15 1.34
0.05 0.11 0.19 0.34 0,47 0,60 0.72 0.84 1,28 1.49 ••• ••,
0.07 0.14 0.25 0.43 0.60 0.75 0.89 1.03 1.54 1.78 2.01 2.23 2.66
0.07 0.14 0.12 0.18 0.18 0.22 0.26 0.27 0.33 0.31 0.39 0.33 0.44 0.36 0.48 0.38 0.64 0.44 0.71 0.46 . . . . . . . . . . . .
.
0.07 0.16 0.27 0.47 0.65 0.82 0.98 1.13 1.70 1.97 . . .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
For each oxygenate, s, calibration data set, obtain the quadratic least-squares fit equation in the following form: r.w.,
=
(b,,)(amt~) + b,(amL) 2
o 1.5 rr O
t)~ r = = 0.99998
FIG. 3
"
I
1
0 An Example
I
I
2 Amount Ratio
of a Quadratic
3
.
.
.
.
.
.
0.08 0.15 0.24 0.39 0.51 0.62 0.73 0.83 1.17 1.33 1.48 1.63 1.90
Total Oxygen ••• 0.13 0.23 0.32 0.41 0.49 ... ... ..• ... .•• •
.
•
( 7 )
11. P r o c e d u r e 11.1 Keep samples refrigerated until ready for analysis. Bring samples to room temperature prior to analysis. 11.2 Tare the sample container and its rubber-faced PTFE-faced sealing cap. Transfer 1 to t0 g of the sample to the container and seal immediately. Weigh the sample container and contents to the nearest 0.1 mg and record the mass of test sample. 11.3 Inject through the rubber membrane a volume of the same internal standard used in generating the standards and reweigh the sample container and contents. Record the difference as the mass of internal standard to the nearest 0.1 mg. The mass of internal standard should be 2 to 6 % of the
t-
0
.
RF,, x = ( R F O ( M W i / M W ~ ) ( N f f N I )
(6)
.5
.
TAME
where: RF,,.,. = relative response factor based on mass of oxygen, RF, = relative mass response factor of the test oxygen compound, as calculated in 10.3 (Eq 3), M W , = molecular mass of the internal standard in the calibration sample, g/mol, MW.~. = molecular mass of the test oxygen compound in the calibration sample as given in Table 2, g/mol, Ns = number of oxygen atoms per molecule of test oxygen compound, and NI = number of oxygen atoms per molecule of internal standard. The relative response factor (mass of oxygen basis) should not deviate from unity by more than _+5 %. Table 2 gives typical relative response factors (on both mass of oxygenates and mass of oxygen basis) for the oxygenates in Fig. 2.
where: rsp~ = response ratio for oxygenate s (y-axis), b,, = linear regression coefficient for oxygenate s, amt, = amount ratio for oxygenate s (x-axis), and bI = quadratic regression coefficient. Figure 3 gives an example of a quadratic least-squares fit for MTBE and the resulting equation in the form of Eq 6: 10.3.2 As a quality assurance check, calculate the relative response factors on a mass % oxygen basis for each oxygen compound according to the following equation:
rr
.
nBA
4
Least-Squares Fit for MTBE
935
qUIl~ D 5599 test sample but not less than 50 mg. 11.4 Ensure that the sample (gasoline plus internal standard) is thoroughly mixed. Transfer an aliquot of the solution to a vial compatible with the autosampler if such equipment is used. Seal the vial with a TFE-fluorocarbonlined septum cap. 11.5 Inject a suitable quantity (0.1 to 1.0 ~tL) of the sample containing internal standard into the chromatograph using the same technique and sample size as used for the calibration standards. The test portion size should be such as not to exceed the capacity of the column or linearity of the detector. 11.6 Acquire peak area and retention time data by way of electronic integrator or computer and, if desired, also by chart recorder. 12. Calculation and Report
12. I Calculate the mass % of each calibrated oxygenate as follows: 12.1.1 After identifying the various oxygenates by retention times, obtain the areas of all calibrated oxygenate peaks and that of the internal standard. Calculate the area response ratio (rsp~) for each of the oxygenates using Eq 4 (10.3. l). 12.1.2 Calculate the amount ratio (amt,) for each calibrated oxygenate in the gasoline sample, by substituting that oxygenate's response ratio (rSPs) and the coefficient of its quadratic calibration curve into Eq 6 (10.3.1) and solving. 12.1.3 Apply Eq 8 to determine the mass % of each calibrated oxygenate. (amt,)( 14/'1)(100 %) w, =
w,
(8)
where:
calibrated oxygenate to mass % oxygen and sum according to the following equation:
O,,n = ]~ [(w~)(16.0)(N~)]
(9)
Ms or [wl][16.0l[Nl]
O,.~n =
[w2][ 16.01[N2]
+
+...
Mt
where: O,.~ = total mass percent oxygen from the calibrated oxygenates, ws = mass % of each oxygenate as determined using Eq 8, N~. = number of oxygen atoms in the oxygenate molecule, M, = molecular mass of the oxygenate as given in Table 2, and 16.0 = atomic mass of oxygen. 12.3.2 Convert the total MTBE-equivalent mass % of uncalibrated oxygenates to mass % oxygen accordings to the following equation: (ws,)(I 6.0)(Ns) 0 ..... i = (11)
Ms.
where: 0,,,,,.~/= total mass % oxygen from the uncalibrated oxygenates, W.,,, = MTBE-equivalent mass % of uncalibrated oxygenates, Ns = number or oxygen atoms in MTBE molecule, M~ = molecular mass of MTBE as given in Table 2, and 16.0 = atomic mass of oxygen. 12.3.3 Calculate the total mass % oxygen in the gasoline sample by summing the contributions from the calibrated components and the uncalibrated components. (12)
0 , , , = O , n + 0 ....... i
w., = mass % of oxygenate in gasoline sample, amt, = amount ratio of oxygenate as determined in 12.1.2, W, = mass of internal standard added to gasoline sample, g, and W~. = mass of gasoline sample, g. 12.1.4 If the mass % of any oxygenate exceeds its calibrated range, gravimetrically dilute a portion of the original sample with oxygenate-free gasoline to a concentration within the calibrated range and analyze the diluted sample in accordance with Section 11 and 12.1. Correct all mass % oxygenate values by multiplying by the dilution factor. 12.2 Calculate the total MTBE-equivalenl mass % of uncalibrated oxygenates as follows: 12.2.1 Sum the peak areas of the uncalibrated oxygenates that are present. Do not include the peak areas due to dissolved oxygen, water, and the internal standard. Calculate the response ratio (rsp.,) for the summed areas of the uncalibrated oxygenates using Eq 4 (10.3.1). 12.2.2 Calculate the amount ratio (amt,) for the uncalibrated oxygenates in the gasoline sample by substituting the response ratio (determined in 12.2.1) and the coefficients of'the MTBE calibration curve into Eq 6 (10.3.1) and solving. 12.2.3 Apply Eq 8 (12.1.3) to determine the total MTBEequivalent mass % of the uncalibrated oxygenates. 12.3 Calculate the total mass % oxygen in the gasoline sample as follows: 12.3.1 Convert the mass % oxygenate of each individual,
( 1O)
M2
12.4 Report the mass % oxygenate of each calibrated oxygenate to the nearest 0.01%. Also report the total mass % oxygen in the gasoline sample to the nearest 0.1%. 13. Quality Control Checks 13.1 Routinely monitor the intralaboratory repeatability and accuracy of the analysis as follows: 13. I. l Intralaboratory Repeatability: 13.1.1.1 Quality control check standards may be prepared from the same oxygenate stocks prepared in 10.2 and covering the range given in 13. I. 1.4. 13.1.1.2 Prepare and analyze duplicates of the quality control check standards at a rate of one per analysis batch or at least one per ten samples, whichever is more frequent. 13.1.1.3 Duplicates should be carried through all sample preparation steps independently. 13.1.1.4 The range (R) for duplicate samples should be less than the following limits: Oxygcnate Methanol Methanol Ethanol MTBE DIPE ETBE TAME
where: 936
Concentration, mass % 0.20 to 1.00 to 1.00 to 0.20 to 1.00 to 1.00 to 1.00 to
L00 12.00 12.00 20.00 20.00 20.00 20.00
Upper Limit lbr Range, mass % 0.010 + 0.043C 0.053C 0.053C 0.069 + 0.029C 0.048C 0.074C 0.060C
( ~ D 5599 14.1.1 Repeatability--The difference between successive results obtained by the same operator with the same apparatus under constant operating conditions on identical test materials would, in the long run and in the normal and correct operation of the test method, exceed the following values only one case in twenty (see Table 3).
C = (C,, + Ca)/2 (13) 1¢ = I C , , - c, iI (14) C,, = concentration of the original sample, and C,/= concentration of the duplicate sample. 13.1.5 If these limits are exceeded, the sources of error in the analysis should be determined, corrected, and all analyses subsequent to and including the last duplicate analysis confirmed to be within the compliance specifications should be repeated. 13.2 lntralaboratory Accuracy." 13.2.1 If the measured concentration of a quality control check standard is outside the range of 100.0 + 6.0 % of the theoretical concentration for a selected oxygenate of 1.0 mass % or above, the sources of error in the analysis should be determined, corrected, and all analyses subsequent to and including the last standard analysis confirmed to be within the compliance specifications should be repeated. 13.2.2 Independent reference standards may be purchased or prepared from materials that are independent of the quality control standards and should not be prepared by the satnc analyst. For the specification limits listed in 13.2.2.2, the concentration of the reference standards should be in the range given in 13.1.1.4. 13.2.2.1 Independent reference standards should be analyzed at a rate of one per analysis batch or at least one per 100 samples, whichever is more frequent. 13.2.2.2 If the measured concentration of an independent reference standard is outside the range of 100.0 +_ 10.0 % of the theoretical concentration for a selected oxygenate of 1.0 mass % or above, the sources of error in the analysis should be determined, corrected, and all analyses subsequent to and including the last independent reference standard analysis confirmed to be within the compliance specifications in that batch should be repeated. 13.3 Control charts may be utilized to monitor the variability of measurements from the quality control check standards and independent reference standards in order to optimally detect abnormal situations and ensure a stable measurement process.
Repeatability for Oxygenates in Gasoline Component Methanol (MeOH) Ethanol (EtOH) lso-propanol (iPA) lerI-Butanol (tBA) n-Propanol (nPA) MTBE st,c-Butanol (sBA) DIPE Iso-butanol (idA) ETBE tert-Pentanol (tAA) n-Butanol (nBA) TAME Total Oxygen
Repeatability 0.07 (X ° 49),4 0.03 (X ° 92) 0.04 (X TM) 0.05 (X ° 65) 0.04 (X °.35) 0.05 (X °.Ss) 0.03 (X TM) 0.05 (X TM) 0.03 (X ° 79) 0.04 (X ° s6) 0.05 (X ° 41) 0.06 (X ° 46) 0.04 (X ° 5~) 0.03 (X ° ~)
a X is the mean mass % of the component.
14.1.2 Reproducibility--The difference between two single and independent results obtained by different operators working in different laboratories on identical material would, in the long run, exceed the following values in only one case in twenty (see Table 3). Reproducibility in Oxygenates in Gasolines Component Methanol (MeOH) Ethanol (EtOH) lso-propanol (iPA) terI-Butanol (tBA) n-Propanol (nPA) MTBE see-Butanol (sBA) DIPE Iso-butanol (idA) ETBE lert-Pentanol (tAA) n-Butanol (nBA) TAME Total Oxygen
14. Precision and Bias 7 14.1 Data obtained from a 10-laboratory round robin on the measurement of 13 oxygenates and total oxygen in 12 gasoline samples were examined. The precision of this test method as determined by a statistical examination of the interlaboratory test results based on 1,2-dimethoxyethane as the internal standard is as follows:
Reproducibility 0.25 (X TM) 0.27 (X °.s°) 0.21 (X °.7 i) 0.20 (X °-s°) 0.17 (X °.ss) O. 10 (X TM) 0.17 (X u,73) 0.16 (X °m) 0.19 (X °.s3) 0.25 (X °.79) 0.18 (X TM) 0.22 (X ° 3o) 0.24 (X ° 69) O. 13 (X TM)
a X is the mean mass % of the component.
14.2 BiasmA statement of bias is currently being developed by the responsible study group. 15. Keywords 15.1 alcohols; DIPE (Di-iso-propylether); ETBE (ethyl tert-butylether); ethanol; gas chromatography; gasoline; methanol; MTBE (methyl tert-butylether); oxygenates; oxygen-selective detection; TAME (tert-amylmethylether)
7 Supporting data are available from ASTM Headquarters. Request RR:D021359.
937
~
D 5599
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned m this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reepproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohocken, PA 19428.
938
~ l ~ ) Designation: D 5622 - 95 Standard Test Methods for Determination of Total Oxygen in Gasoline and Methanol Fuels by Reductive Pyrolysis This standard is issued under the fixed desagnatlon D 5622: the number ~m~nediately following the destgnatlon indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 1.I These test methods cover the quantitative determination of total oxygen in gasoline and methanol fuels by reductive pyrolysis. 1.2 Precision data are provided for 1.0 to 5.0 mass % oxygen in gasoline and for 40 to 50 mass % oxygen in methanol fuels. 1.3 Several types of instruments can be satisfactory for these test methods. Instruments can differ in the way that the oxygen-containing species is detected and quantitated. However, these test methods are similar in that the fuel is pyrolyzed in a carbon-rich environment. 1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.5 This standard does not purport to address all of the
are pyrolyzed, and the oxygen is quantitatively converted into carbon monoxide. 3.2 A carrier gas, such as nitrogen, helium, or a helium/ hydrogen mixture, sweeps the pyrolysis gases into any of four downstream systems of reactors, scrubbers, separators, and detectors for the determination of the carbon monoxide content, hence of the oxygen in the original fuel sample. The result is reported as mass % oxygen in the fuel.
4. Significance and Use 4.1 These test methods cover the determination of total oxygen in gasoline and methanol fuels, and they complement Test Method D 4815, which covers the determination of several specific oxygen-containing compounds in gasoline. 4.2 The presence of oxygen-containing compounds in gasoline can promote more complete combustion, which reduces carbon monoxide emissions. The Clean Air Act (1992) requires that gasoline sold within certain, specified geographical areas contain a minimum percent of oxygen by mass (presently 2.7 mass %) during certain portions of the year. The requirement can be met by blending compounds such as methyl tertiary butyl ether, ethyl tertiary butyl ether, and ethanol into the gasoline. These test methods cover the quantitative determination of total oxygen which is the regulated parameter.
safety concerns, ~f any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability o.f regulatory limitations prior to use. 2. Referenced Documents 2.1 A S T M Standards." D 1298 Practice for Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method 2 D 4052 Test Method for Density and Relative Density of Liquids by Digital Density Meter 3 D4057 Practice for Manual Sampling of Petroleum and Petroleum Products 3 D 4815 Test Method for Determination of MTBE, ETBE, TAME, DIPE, tertiary-Amyl Alcohol and C~ to Ca Alcohols in Gasoline by Gas Chromatography 4 2.2 Other Standard." Clean Air Act (1992) -~
5. Apparatus
5.1 Oxygen Elemental Analyzer6,7.8.9--A variety of instrumentation can be satisfactory. However, the instrument must reductively pyrolize the specimen and convert oxygen to carbon monoxide. 5.1.1 Test Method A6--Helium carrier gas transports the pyrolysis products through a combination scrubber to remove acidic gases and water vapor. The products are then transported to a molecular sieve gas chromatographic column where the carbon monoxide is separated from the other pyrolysis products. A thermal conductivity detector generates a response that is proportional to the amount of carbon monoxide. 5.1.2 Test Method BT--Nitrogen carrier gas transports the pyrolysis products through a scrubber to remove water vapor. The pyrolysis products then flow through tandem
3. Summary of Test Methods 3.1 A fuel specimen of 1 to 10 !aL is injected by syringe into a 950 to 1300"C high-temperature tube furnace that contains metallized carbon. Oxygen-containing compounds
6Carlo Erba Models 1106 and 1108 have been found satisfactory for these analyses. They are available from CE Elantech, Inc., 170 Oberlin Ave. N., Ste 5, Lakewood, NJ 08701. 7 Leco Model RO-478 has been found satisfactory for this analysts. It is avadable from Leco Corp., 3000 Lakeview Ave., St. Joseph. MI 49085. K Perkin-Elmer Series 2400 has been found satisfactory Ibr this analysis It is avadable from Perkin-Elmcr Corp., 761 Mam Ave., Norwalk, CT 06859. '~ UIC. Inc./Coulomemcs Model 5012 CO,,. coulometer and Model 5220 autosampler-furnace have been found satisfactory for this analysts. "l'he~, are available from UIC Inc., Box 863, Joliet. IL 60434.
~These test methods are under the junsdlctton of Committee D-2 on Petroleum Products and Lubricants and are the direct responsibihty of Subcommince D02.03.0A on Chemical Methods, ('urrent edition approved Aug. 15, 1995. Published October 1995. Originally pubhshed as D 5622.- 94 t,as! previous edition D 5622 - 94. , Innttal Bool~ o fASTM Standard~', Vol 05.0 I. hmual Book of ASTM Slandard~'. Vol 05.02. 4 Innual Book o / A S T M Standards, Vol 05.03. Federal Register, Vol 57, No. 24, Feb. 5, 1992, p. 4408.
939
~
D 5622
infrared detectors that measure carbon monoxide and carbon dioxide, respectively. 5.1.3 Test Method C8~A mixture of helium and hydrogen (95:5 %), helium, or argon transports the pyrolysis products through two reactors in series. The first reactor contains heated copper which removes sulfur-containing products. The second reactor contains a scrubber which removes acidic gases and a reactant which oxidizes carbon monoxide to carbon dioxide (optional). The product gases are then homogenized in a mixing chamber, which maintains the reaction products at absolute conditions of temperature, pressure, and volume. The mixing chamber is subsequently depressurized through a column that separates carbon monoxide (or carbon dioxide, if operating, in the oxidation mode) from interfering compounds. A thermal conductivity detector measures a response proportional to the amount of carbon monoxide or carbon dioxide. 5.1.4 Test Method D9~Nitrogen carder gas transports the pyrolysis products through scrubbers to remove acidic gases and water vapor. A reactor containing cupric oxide at 325"C oxidizes the carbon monoxide to carbon dioxide, which in turn is transported into a coulometric carbon dioxide detector. Coulometrically generated base titrates the acid formed by reacting carbon dioxide with monoethanolamine. 5.2 A technique must be established to make a quantitative introduction of the test specimen into the analyzer. Specimen vials and transfer labware must be clean and dry. 5.3 For instruments that measure carbon monoxide only, pyrolysis conditions must be established to quantitatively convert oxygen to carbon monoxide. 5.4 A system of scrubbers and separators must be established to effectively remove pyrolysis products that interfere with the detection of carbon monoxide or carbon dioxide, or both. 5.5 The detector responses must be linear with respect to concentration, or nonlinear responses must be detectable and accurately related to concentration. 5.6 Selected items are available from the instrument manufacturer. 5.6.1 Pyrolysis Tubes, 5.6.2 Scrubber Tubes, and 5.6.3 Absorber Tubes.
6. Reagents 6.1 Purity of Reagents~°~Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 6.2 Calibration Standards:
6.2.1 NIST SRM 18371 t, which contains certified concentrations of methanol and t-butanol in reference fuel, can be used to calibrate the instrument for the analysis of oxygenates in gasoline. 6.2.2 Anhydrous methanol, 99.8 % minimum assay, can be used to calibrate the instrument for the analysis of methanol fuels. 6.2.3 Isooctane, or other hydrocarbons, can be used as the blank provided the purity is satisfactory. 6.3 Quality Control Standard--NIST SRM 1838 ~t can be used to check the accuracy of the calibration. 6.4 The instrument manufacturers require additional reagents. 6.4.1 Test Method A: 6 6.4.1.1 Anhydrone (anhydrous magnesium perchlorate), 6.4.1.2 Ascarite II (sodium hydroxide on silica), 6.4.1.3 Helium carder gas, 99.995 % pure, 6.4.1.4 Molecular sieve, 5 A, 60 to 80 mesh, 6.4.1.5 Nickel wool, 6.4.1.6 Nickelized carbon, 20 % loading, 6.4.1.7 Quartz chips, and 6.4.1.8 Quartz wool. 6.4.2 Test Method B:7 6.4.2.1 Anhydrone (anhydrous magnesium perchlorate), 6.4.2.2 Carbon pyrolysis pellets, and 6.4.2.3 Nitrogen carder gas, 99.99 % pure. 6.4.3 Test Method C.'8 6.4.3.1 Anhydrone (anhydrous magnesium perchlorate), 6.4.3.2 Ascarite II (sodium hydroxide on silica), 6.4.3.3 Carder gas, either helium (95 %)/hydrogen (5 %), mixture, 99.99 % pure; helium, 99.995 % pure; or argon, 99.98 % pure, 6.4.3.4 Copper plus, wire form, and 6.4.3.5 Platinized carbon. 6.4.4 Test Method 9:9 6.4.4.1 Anhydrone (anhydrous magnesium perchlorate), 6.4.4.2 Ascarite II (sodium hydroxide on silica), 6.4.4.3 Copper (II) oxide, 6.4.4.4 Coulometric cell solutions, including a cathode solution of monoethanolamine in dimethyl sulfoxide and an anode solution of water and potassium iodide in dimethyl sulfoxide, 6.4.4.5 Nickelized carbon, 20 % loading, and 6.4.4.6 Nitrogen carder gas, 99.99 % pure.
7. Sampling 7.1 Take samples in accordance with the instructions in Practice D 4057. 7.2 Visually inspect the samples, and when there is evidence of nonuniformity, take fresh samples. 7.3 Store the samples in a cold room or a laboratory refrigerator designed for storage of chemicals. 8. Preparation of Apparatus 8.1 Prepare the instrument in accordance with the manufacturer's recommendations. These test methods require that correct operating procedures are followed for the model
"~ Reagent Chemicals, Amerwan Chemwal Societ.v Spectficatton.~, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standard~" ./or Laboratory C'lwmicals, BDH Ltd., Poolc, Dorset, U.K., and the United States Pharmacopeta and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD.
~J Available from the National Institute of Standards and Technology, Gaithersburg, MD 20899.
940
~
D 5622 10. Calculation and Report
used. Instrument design differences make it impractical to specify all of the required operating conditions. 8.2 The carrier gas can be scrubbed to remove traces of oxygen and oxygen-containing compounds.
10.1 Calculate the mass % oxygen for the QC standard and samples as follows:
RxK
Mass % Oxygen = M x r
where: R = blank corrected instrument response, K = K-factor, refer to Eq l, assume unity for Test Method D, M = mass of sample, mg, = volume (IxL) x density (g/mL), and r = recovery, refer to 9.4.3, assume unity for Test Methods A, B, and C. 10.2 For instruments with computer data systems, the calculation of the K-factor (Eq l) and the calculation of mass % oxygen (Eq 2) can be automatic with a digital readout provided. 10.3 Report mass % oxygen to the nearest 0.01%.
9. Calibration and Standardization
9.1 Calibration for Test Methods A, B, and C, Oxygenates in Gasoline: 9.1.1 Use a syringe to introduce 1 to 10 IxL, or 1 to 10 mg, of the blank. The amount of specimen must be precisely known. Measure the response. Repeat the introduction and measurement until stable readings are observed. 9.1.2 In similar fashion, introduce 1 to 10 lxL, or 1 to 10 mg, of SRM 1837 and measure the response. Repeat two times with the same quantity of the SRM. If the blank corrected responses do not agree within 2 % relative, take corrective action and repeat the calibration. 9.1.3 Calculate the K-factor as follows: K--
Cstd X Mst d
(2)
11. Precision and Bias 12
(1)
I I. l Precision--The precision of these test methods was determined by statistical analysis of interlaboratory test results. Twelve laboratories analyzed in duplicate eight different samples, providing a total of thirteen data sets. One laboratory used two different test methods. The breakdown on data sets by test method is: Test Method A, three; Test Method B, two; Test Method C, three; Test Method D, five. The statistical analysis was performed on the set of 13 data sets because the reductive pyrolysis technique is common to all four test methods. Separate statistics were not determined for individual test methods. The sample set included anhydrous methanol and gasoline stocks that were spiked with one or more of the following: isobutanol, n-butanol, secbutanol, tert-butanol, di-isopropyl ether, ethanol, ethyl leftbutyl ether, methanol, methyl tert-butyl ether, n-propanol, isopropanol, tert-amyl methyl ether. 1 l . l . l Repeatability--The difference between two test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test materials would, in the long run, in the normal and correct operation of the test method, exceed the following values in only one case in twenty.
Ravg
where: mass % oxygen in the SRM, mass of the SRM, mg, volume of the SRM (~tL) × density of the SRM (g/mL), and Ravg --- average of the blank corrected responses. NOTE l--Density can be determinedby Test Method D 1298 or Test Method D 4052. Cstd Mst d =
9.2 Cafibration for Test Methods A, B, and C, Methanol Fuels--Repeat procedure 9.1; however, substitute anhydrous methanol for the SRM. For methanol fuels, a unique K-factor can be necessary. 9.3 Calibration for Test Method D--This test method does not require calibration; however, a quality control standard must be analyzed to ensure proper operation of the instrument. A blank must also be analyzed periodically to ensure consistent responses. 9.4 Quality Control (QC): 9.4.1 Introduce the QC standard SRM 1838 in the same manner as the calibration standards. Calculate the percent oxygen (m/m) as described in Section 10. 9.4.2 When results obtained on the QC standard do not agree with the certified values within 2 % relative, take corrective action and repeat the calibration and quality control. 9.4.3 For Test Method D, when the recovery of oxygen from the QC SRM is less than 0.85 (that is, 85 %), take corrective action and repeat the quality control. Recoveries that are greater than 0.85 but less than unity can be used to correct the calculated result (refer to the r parameter in Section 10). 9.5 Procedure: 9.5.1 Introduce the samples, and record the instrument response. Calculate the results as described in Section 10. Use the appropriate K-factor for oxygenates in gasoline and methanol fuels. 9.5.2 Recalibrate the instrument with the appropriate calibration standard after each set of ten samples.
Mass % Oxygen Range
Repeatability, Mass % Oxygen
1.0 to 5.0 % 40 to 50 %
0.06 % 0.81%
1 I. 1.2 Reproducibility--The difference between two single and independent results, obtained by different operators working in different laboratories on identical test materials, would in the long run, in the normal and correct operation of the test method, exceed the following values in only one case in twenty. Mass % Oxygen Range
Reproducibility, Mass % Oxygen
1.0 to 5.0 % 40 to 50 %
0.26 % 0.81%
11.2 Bias--Bias was determined from interlaboratory results obtained on NIST SRM 1838, which contains ,2 Interlaboratory study data are available from ASTM by requesting RR:D021338.
941
~
D 5622 12. Keywords
ethanol. The null hypothesis that was tested was that the true difference between the grand average result and the NIST certified value is zero. The result of the hypothesis testing was that if the true difference was zero, the determined difference would occur by chance approximately 50 % of the time. Hence, the null hypothesis of no difference or no bias is accepted.
12.1 carbon dioxide; carbon monoxide; di-isopropyl ether; ethanol; ethyl tert-butyl ether; isobutanol; isopropanol; methanol; methyl tert-butyl ether; n-butanol; n-propanol; oxygen; reductive pyrolysis; see-butanol; tert-butanol; tertamyl methyl ether
APPENDIX
(Nonmandatory Information) XI. EFFECT OF WATER IN GASOLINE CONTAINING OXYGENATES anol, di-isopropyl ether, n-propanol. A few millilitres of each water-spiked gasoline were treated with 200 mg of potassium carbonate prior to analysis. The results obtained on the treated, spiked samples did not differ from the results obtained on the neat gasolines by more than 0.02 mass % oxygen, which is within the repeatability of these test methods. X I.3 The literature ~4 describes an alternative technique for removing water from gasoline, namely, treatment of the gasoline with Molecular Sieve 3A. In an experiment similar to that described in X 1.2, water-spiked, oxygenated gasolines were pretreated with Sieve 3A prior to analysis by Test Method B. The results obtained on the sieve treated, spiked samples did not differ from the results obtained on the neat gasolines by more than the repeatability of these test methods.
X I.1 The Clean Air Act (1992) requirement for oxygenates in gasoline implicitly excludes water-borne oxygen from the specification for total oxygen. Experimental evidence indicates that for typical oxygenated gasolines, the maximum amount of soluble water is approximately 0.1 mass %. This corresponds to 0.09 mass % oxygen which is very close to the repeatability of these test methods. When oxygen from dissolved water must be excluded from the analysis, the gasoline can be pretreated with potassium carbonate or Molecular Sieve 3A prior to analysis by these test methods. X 1.2 According to the patent literature 13, gasoline can be treated with potassium carbonate to remove dissolved water. Test Method B was used to analyze five different gasolines that were spiked with 0.1 mass % water. These gasolines contained one or more of the following oxygenates at concentrations typical of gasolines: tert-amyl methyl ether, ethanol, ethyl tert-butyl ether, see-butanol, n-butanol, meth-
14 Burfield, D. R., and Smithers, R, H., "Desiccant Efficiency in Solvent and Reagent Drying," Journal of Organic Chemistry, Vol 48, No. 14, 1983, pp. 2420-2422.
~3 U.S. Patent No. 4 539 013, Sep. 3, 1985.
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to rewsion at any time by the responsible technical committee and must be reviewed every five years and ff not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, whtch you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St, Philadelphia, PA 19103.
942
(~l~
Designation: D 5623 - 94
Standard Test Method for Sulfur Compounds in Light Petroleum Liquids by Gas Chromatography and Sulfur Selective Detection 1 This standard is issued under the fixed designation D 5623; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last rcapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 This test method covers the determination of volatile sulfur-containing compounds in light petroleum liquids. This test method is applicable to distillates, gasoline motor fuels (including those containing oxygenates) and other petroleum liquids with a final boiling point of approximately 230"C (450"F) or lower at atmospheric pressure. The applicable concentration range will vary to some extent depending on the nature of the sample and the instrumentation used; however, in most cases, the test method is applicable to the determination of individual sulfur species at levels of 0.1 to 100 mg/kg. 1.2 The test method does not purport to identify all individual sulfur components. Detector response to sulfur is linear and essentially equimolar for all sulfur compounds within the scope (1.1) of this test method; thus both unidentified and known individual compounds are determined. However, many sulfur compounds, for example, hydrogen sulfide and mercaptans, are reactive and their concentration in samples may change during sampling and analysis. Coincidently, the total sulfur content of samples is estimated from the sum of the individual compounds determined; however, this test method is not the preferred method for determination of total sulfur. 1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
2. Referenced Documents 2.1 ASTM Standards: D2622 Test Method for Sulfur in Petroleum Products (X-Ray Spectrographic Method) 2 D 3120 Test Method for Trace Quantities of Sulfur in Light Liquid Petroleum Hydrocarbons by Oxidative Microcoulometry2 D4057 Practice for Manual Sampling of Petroleum and Petroleum Products2 J This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.04.0L on Gas Chromatography. Current edition approved Dec. 15, 1994. Published February 1995. 2 Annual Book of ASTM Standards, Vol 05.02.
D 4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards 2 D 4626 Practice for Calculation of Gas Chromatographic Response Factors 2
3. Summary of Test Method 3.1 The sample is analyzed by gas chromatography with an appropriate sulfur selective detector. Calibration is achieved by the use of an appropriate internal or external standard. All sulfur compounds are assumed to produce equivalent response as sulfur. 3.2 Sulfur Detection--As sulfur compounds elute from the gas chromatographic column they are quantified by a sulfur selective detector that produces a linear and equimolar response to sulfur compounds; for example sulfur chemiluminescence detector or atomic emission detector (AED 3) used in the sulfur channel. 4. Significance and Use 4.1 Gas chromatography with sulfur selective detection provides a rapid means to identify and quantify sulfur compounds in various petroleum feeds and products. Often these materials contain varying amounts and types of sulfur compounds. Many sulfur compounds are odorous, corrosive to equipment, and inhibit or destroy catalysts employed in downstream processing. The ability to speciate sulfur compounds in various petroleum liquids is useful in controlling sulfur compounds in finished products and is frequently more important than knowledge of the total sulfur content alone. 5. Apparatus 5.1 Chromatograph--Use a gas chromatograph (GC) that has the following performance characteristics: 5.1.1 Column Temperature Programmer--The chromatograph must be capable of linear programmed temperature operation over a range sufficient for separation of the components of interest. The programming rate must be sufficiently reproducible to obtain retention time repeatability of 0.05 rain (3 s) throughout the scope of this analysis. 5.1.2 Sample Inlet System--The sample inlet system must have variable temperature control capable of operating continuously at a temperature up to the maximum column temperature employed. The sample inlet system must allow a constant volume of liquid sample to be injected by means of a syringe or liquid sampling valve. 3 The AED is manufactured by Hewlett-Packard Co., 2850 Centerville Rd., Wilmington, DE 19808-1610.
943
o ssaa 5.1.3 Carrier and Detector Gas Control--Constant flow control of carder and detector gases is critical to optimum and consistent analytical performance. Control is best provided by the use of pressure regulators and fixed flow restrictors or mass flow controllers capable of maintaining gas flow constant to _ 1% at the required flow rates. The gas flow rate is measured by any appropriate means. The supply pressure of the gas delivered to the gas chromatograph must be at least 70 kPa (10 psig) greater than the regulated gas at the instrument to compensate for the system back pressure of the flow controllers. In general, a supply pressure of 550 kPa (80 psig) is satisfactory. 5.1.4 Cryogenic Column Cooling--An initial column starting temperature below ambient temperature may be required to provide complete separation of all of the sulfur gases when present in the sample. This is typically provided by adding a source of either liquid carbon dioxide or liquid nitrogen, controlled through the oven temperature circuitry. 5.1.5 Detector--A sulfur selective detector is used and shall meet or exceed the following specifications: (a) linearity of 104, (b) 5 pg sulfur/s minimum detectability, (c) approximate equimolar response on a sulfur basis, (d) no interference or quenching from co-eluting hydrocarbons at the GC sampling volumes used. 5.2 Column--Any column providing adequate resolution of the components of interest may be used. Using the column and typical operating conditions as specified in 5.2.1, the retention times of some sulfur compounds will be those shown in Table 1. The column must demonstrate a sufficiently low liquid phase bleed at high temperature, such that loss of the detector response is not encountered while operating at the highest temperature required for the analysis. 5.2.1 Typical Operating Conditions: 5.2.1.1 Column--30 m by 0.32 mm inside diameter fused TABLE 1
Sulfur Compounds
Retention Time (rain) 0.95 1.21 1.34 3.43 7.20 7.76 8.24 8.92 10.04 10.42 10.53 12.01 12.04 12.18 12.82 13.33 13.90 14.71 14.84 17.89 24.55 24.66 24.77 24.88 28.64
6. Reagents and Materials 6.1 Purity of Reagents--Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where such specifications are available. 4 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 6.1.1 Alkane SolventmSueh as, iso-octane (2,2,4-trimethylpcntane), Reagent grade, for use as solvent (diluent) in preparation of system test mixtures and for preparation of internal standard stock solution (Warning--See Note 1). NOTE h Warning--Iso-octane is flammable and can be harmful when ingested or inhaled.
Typical Retention Times for Common Sulfur Compounds ~
Hydrogen Sulfide Carbonyl Sulfide Sulfur Dioxide Methanethiol Ethanethiol Dimethyl Sulfide Carbon Disulfide 2-Propanethlol 2-methyl-2-propanethlol 1-Propanethlol Ethylmethyl sulfide 2-Butanethiol Thiophene 2-methyl-l-propanethiol Diethyl Sulfide 1-Butanethiol Dimethyl Disulfide 2-Methylthiophene 3-Methylthiophene Diethyl Disulfide Methylbenzothiophene Methylbenzothiophene Methylbenzothiophene Methylbenzothiophene Diphenyl sulfide
silica wall coated open tube (WCOT) column, 4-~tm thick film of methylsilicone. 5.2.1.2 Sample size--O. 1 to 2.0-1xL. 5.2.1.3 Injector--Temperature 275"C; Split ratio: 10:I (10 % to column). 5.2.1.4 Column Oven--lO*C for 3 min, 10*C/min to 250"C, hold as required. 5.2.1.5 Carrier Gas--Helium, Head pressure: 70 to 86 kPa (10 to 13 psig). 5.2.1.6 Detector--Sulfur chemiluminescence detector. 5.3 Data Acquisition: 5.3.1 RecordermThe use of a 0 to 1 mV recording potentiometer, or equivalent, with a full-scale response time of 2 s, or less, is suitable to monitor detector signal. 5.3.2 Integrator--The use of an electronic integrating device or computer is recommended for determining the detector response. The device and software must have the following capabilities: (a) graphic presentation of the chromatogram, (b) digital display of chromatographic peak areas, (c) identification of peaks by retention time or relative retention time, or both, (d) calculation and use of response factors, (e) internal standardization, external standardization, and data presentation.
6.1.2 Aromatic Solvent--Such as, toluene, Reagent grade, for use as solvent (diluent) in preparation of system test mixtures (Warning--See Note 2). NOTE 2: Warning--Reagent grade toluene is flammable and is toxic by inhalation, ingestion, and absorption through skin.
6.1.3 Carrier Gas--Helium or nitrogen of high purity (Warning--See Note 3). Additional purification is recommended by the use of molecular sieves or other suitable agents to remove water, oxygen, and hydrocarbons. Available pressure must be sufficient to ensure a constant carrier gas flow rate (see 5.1.3). NOTE 3: WarningnHelium and nitrogen are compressed gases under high pressure.
6.1.4 Detector Gases--Hydrogen, nitrogen, air, and ox4 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Peele, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmaceutical Convention, inc. (USPC), Rockville, MD.
A Conditions specified in 5.2.1.
944
~
D 5623 detector operating conditions are shown in 5.2.1. 7.2 Detector--Place in service in accordance with the manufacturer's instructions. After sufficient equilibration time (for example, 5 to 10 min), adjust the detector output signal or integrator input signal to approximately zero. Monitor the signal for several minutes to verify compliance with the specified signal noise and drift. 7.3 System Performance Specification--The inlet system should be evaluated for compatibility with trace quantities of reactive sulfur compounds. Inject and analyze a suitable amount (for example, 0.1 to 2.0-~tL) of the system test mixture (6.1.8). All sulfur compounds should give essentially equimolar response and should exhibit symmetrical peak shapes. Relative response factors should be calculated for each sulfur compound in the test mixture (relative to a referenced component) in accordance with Practice D 4626 or Eq. 1:
ygen may be required as detector gases. These gases must be free of interferring contaminants, especially sulfur compounds. (Warning--See Note 4). Note 4: Warning--Hydrogenis an extremelyflammablegas under high pressure. Warning--Compressedair and oxygenare gases under high pressure and they support combustion. 6.1.5 External Standards--The sulfur compounds and matrices of external standards should be representative of the sulfur compounds and sample matrices being analyzed. Test Methods D2622 and D3120 can be used to analyze materials for calibration of this test method. The internal standardization procedure can also be used for generating external standards. Alternatively, primary standards prepared as described in 6.1.4 can be used for method calibration when it is demonstrated that the matrix does not affect calibration. Only one external standard is necessary for calibration, provided that the system performance specification (7.3) is met. An external standard must contain at least one sulfur compound at a concentration level similar, for example, within an order of magnitude to those in samples to be analyzed. 6.1.6 Internal Standards--Diphenyl sulfide, 3-chlorothiophene, and 2-bromothiophene are examples of sulfur compounds that have been used successfully as internal standards for samples within the scope of this test method (Warning--See Note 5). Any sulfur compound is suitable for use as an internal standard provided that it is not originally present in the sample, and is resolved from other sulfur compounds in the sample. Use the highest purity available (99 + % when possible). When purity is unknown or questionable, analyze the material by any appropriate means and use the result to provide accurate internal standard quantities. 6.1.6.1 An internal standard stock solution should be made up in the range of 0.1 to 1 g of the internal standard on a sulfur basis to 1 kg of solvent. 6.1.7 Sulfur Compound Standards--99 + % purity (if available). Obtain pure standard material of all sulfur compounds of interest (Warning--See Note 5). If purity is unknown or questionable, analyze the individual standard material by any appropriate means and use the result to provide accurate standard quantities.
Rr.
C. x A. Cr x A.
(l)
= ~
where: Rr. = relative response factor for a given sulfur compound, C. --- concentration of the sulfur compound as sulfur, A~ = peak area of the sulfur compound, Cr = concentration of referenced sulfur standard as sulfur, and Ar = peak area of the referenced sulfur standard. The relative response factor (R~.) for each sulfur compound should not deviate from unity by more than +10 %. Deviation of response by more than __.10% or severe peak asymmetry indicates a chromatography or detector problem that must be corrected to ensure proper selectivity, sensitivity, linearity, and integrity of the system. If necessary, optimize the system according to instructions from the manufacturers.
NOTE 5: Warning~Sulfur compounds can be flammable and harmfulor fatal wheningestedor inhaled. 6.1.8 System Test Mixture--Gravimetrically prepare a stock solution of sulfur compounds in accordance with Practice D 4307. This solution should cover the volatility range encountered in samples of interest; for example, dimethyl sulfide (~0.1 g/kg), 2-propanethiol (~0.1 g/kg), dimethyl disulfide (~10 g/kg), 3-methylthiophene (~100 g/kg), and (~10 g/kg) benzothiophene. Prepare a working test mix solution by making a 1000:1 dilution of the stock solution in a mixture of 10 % toluene in iso-octane. Although 2-propanethiol is not stable in the long term, peak asymmetry of a thiol (mercaptan) is an indicator of GC system activity.
8. Sampling 8.1 Appropriate sampling procedures are to be followed. This test method is not suitable for liquified petroleum gases. Volatile liquids to be analyzed by this test method shall be sampled using the procedures outlined in Practicc D 4057. A sufficient quantity of sample should be taken for multiple analyses to be performed (at least 10 to 20 g for quantitation by internal standardization). Store all samples and standard blends at a temperature of 7 to 15°C (45 to 60"F). Do not open the sample or standard container at temperatures above 15"C (60"F). 9. Procedure 9.1 A list of typical apparatus and conditions is provided in 5.2.1. Table 2 provides a listing of the retention times for common sulfur compounds that are typical for the column and conditions specified in 5.2.1. Whenever possible, the retention times of sulfur compounds of interest should be TABLE 2
Sulfur Chemiluminescence Detection and Internal
Standardization Concentration, mg/kg S
7. Preparation of Apparatus 7.1 Chromatograph--Place in service in accordance with the manufacturer's instructions. Typical chromatograph and
Single stable component Total sulfur
945
1 to 100 10 to 200
Repeatability, mg/kg S 0.11 x Concentration 0.12 x Concentration
o s623 determined experimentally. Figure 1 shows a chromatogram from a typical analysis. 9.2 Sample Preparation for Analysis by lnternal Standardization--Add a quantity of suitable internal standard dissolved in iso-octane or another suitable solvent (internal standard stock solution, 6.1.6.1), to an accurately measured quantity of sample on a gravimetric (mass) basis. The final concentration of the internal standard in the sample aliquot, on a sulfur basis, should be approximately one half of the concentration range of sulfur compounds in the original sample. A concentration of approximately 1 to 50 mg/kg of internal standard on a sulfur basis has been used successfully for most samples. 9.3 Sample Analysis by External Standardization--At least once a day, or as frequently as deemed expedient, use the external standard(s) (6.1.5) to calibrate the instrument. The volume of external standard injected for calibration must be exactly the same as the sample volume injected for analysis. 9.4 Chromatographic Analysis--Introduce a representative aliquot of sample into the gas chromatograph. For internal standardization, the sample aliquot must contain a measured quantity of internal standard (6.1.6). Exercise care that the amount of sample and standard injected does not cause detector saturation (indicated by flat-topped peaks). Typical sample size ranges from 0.1 to 2.0-gL. Obtain the chromatographic data by way of a potentiometric recorder (graphic), digital integrator, or computer based chromatographic data system. Examine the graphic display or digital data for any errors. 10. Calculations
10.1 Mass Concentration of Sulfur Compounds as Sulfur-After identifying the sulfur compounds of interest by retention time, measure the area of each sulfur peak. 10.1.1 Sulfur Concentration by Internal Standardization-Compare the area response of each sulfur compound of interest to that of the internal standard. Calculate the concentration of each sulfur peak according to Eq. 2:
C. =
C, x W, x A . (2)
Wsx X A i
where: C, -- concentration (mg/kg) of sulfur compound as sulfur, C~ = concentration (mg/kg) of internal standard in stock solution calculated as sulfur, IV,. = mass of internal standard stock solution added to the sample, A, = peak area of the sulfur compound, W,x = mass of sample aliquot, and A~ = peak area of the internal standard. 10.1.2 Sulfur Concentration by External Standardizat i o n - A n appropriate external standard (6.1.5) is chosen for calibration. The sulfur compound(s) and matrix of the external standard chosen should be representative of the sample(s) being analyzed. Compare the area response of each
sulfur compound of interest to that of the external standard. Calibrate the concentration of each sulfur peak according to Eq. 3: c. =
Ce × De × A n Dsx × A e
(3)
where: 6", -- concentration (mg/kg) of sulfur compound as sulfur, Ce = concentration (mg/kg) of external standard calculated as sulfur, De -- density of external standard matrix, A, -- peak area of the sulfur compound, D= -- density of sample matrix, and A e = peak area of the external standard. This equation assumes that equivalent volumes of sample and standard are injected. 10.2 Report the concentration of each sulfur compound as sulfur in units of mg/kg (ppm wt) to the appropriate number of significant figures. 10.3 Mass Concentration of Total Sulfur in Sample--Sum the sulfur content of all sulfur components (knowns and unknowns) in the sample to arrive at its total sulfur value according to Eq. 4: Cs, o, = Z c . (4) where: Cs~ol = concentration of total sulfur in the sample. 10.4 Report the concentration of total sulfur in units of mg/kg to the appropriate number of significant figures. 10.5 Mass Concentration of Sulfur Compounds as Compound-In 9.1 the concentration of sulfur compounds is reported on a sulfur basis. In some instances the concentration of sulfur compounds as compound is of interest. This conversion is made according to Eq. 5:
CnxM S x 32.07
cw = -
(5)
where: Cw --concentration of the sulfur compound as compound, 6", -- concentration of sulfur compound as sulfur, M = Molar mass of the compound in g/mol, S -- number ofsulfur atoms in the molecular formula of the compound, and, 32.07 = the mass of one tool of sulfur, g. 11. Precision and Bias s
11.1 Data is insufficient for determining precision and bias of AED use in this test method. Data is sufficient, however, for determining precision of sulfur chemiluminescence detector used in this test method. The precision of this test method as determined by the statistical examination of the interlaboratory test results is as follows: s Supporting data are available from ASTM Headquarters. Request RR:D021335.
946
~
D 5623 17
12. C2-thiophenes 1. Ethanethiol 13. Diethyl disulfide 2. Dimethyl sulfide 14. Benzothiophene 3. Carbon disulfide 15. Cl-benzothiophenes 4. 2-Propanethiol 16, C2-benzothiophenes 5. 2-Methyl-2-propanethiol 17, Diphenyl sulfide (Int Std) 6. 1-Propanethlol 7. Ethylmethyl sulfide 8. Thlophene/2-Methyl-l-propanethiol 9. DImethyl Disulfide 10. 2-Methylthiophene 11.3-Methylthlophene ,,
14
15
ul
8 i
12 ~
1
0
I 16
4 5 67 I
0.0
I
I
I
I
I
4.0
I
8.0
I
I
16.0 20.0 12.0 Time (minutes)
24.0
28.0
NOTE--Conditionsas shown in 5.2.1, column: 30 m, 0.32 mm inside diameter, 4 I~m methyl silicone wall coated open tube fused silica; temperature program: -10"C for 3 rain to the final required temperature at a rate of 10°C/rain. FIG. 1 Chromatogram from the analysis of • typical gasoline sample containing approximately 85 ppm wt total sulfur. TABLE 3
Sulfur Chemiluminescence Detection and External Standardization
Single stable component Total sulfur TABLE 4
Concentration, mg/kg S
Repeatability, mg/kg S
1 to 100 10 to 200
0.31 x Concentration 0.24 x Concentration
Sulfur Chemiluminescence Detection and Internal
Standardization
Single stable component Total sulfur
Concentration, mg/kg S
Reproducibility, mg/kg S
1 to 100 10 to 200
0.42 x Concentration 0.33 x Concentration
TABLE 5 Sulfur ChemiluminescenceDetection and External Standardization Concentration, mg/kg S Reproducibility, mg/kgS Singlestablecomponent Total sulfur
1 to 100 10 to 200
11.1.1 RepeatabilitymThe difference between successive test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following values only in one case in twenty (see Tables 2 and 3). 11.1.2 ReproducibilitymThe difference between two single and independent results obtained by different operators working in different laboratories on identical test material would, in the long run, exceed the following values only in one case in twenty (see Tables 4 and 5). 11.2 Bias--Since there is no accepted reference material suitable for measuring bias for this test method, no statement of bias can be made. 12. Keywords 12.1 atomic emission detection; gas chromatography; sulfur chemiluminescence detection; sulfur compounds
0.53 x Concentration 0.52 x Concentration
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reepproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
947
(~l~ Designation: D 5708 - 95a Standard Test Methods for Determination of Nickel, Vanadium, and Iron in Crude Oils and Residual Fuels by Inductively Coupled Plasma (ICP) Atomic Emission Spectrometry I This standard is issued under the fixed designation D 5708; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
D 5185 Test Method for the Determination of Additive Elements, Wear Metals, and Contaminants in Used Lubricating Oils by Inductively Coupled Plasma Atomic Emission Spectrometry5
1. Scope 1.1 These test methods cover the determination of nickel, vanadium, and iron in crude oils and residual fuels by inductively coupled plasma (ICP) atomic emission spectrometry. Two different test methods are presented. 1.2 Test Method A (Sections 7 to 11 and 18 to 21)--ICP is used to analyze a sample dissolved in an organic solvent. This test method uses oil-soluble metals for calibration and does not purport to quantitatively determine or detect insoluble particulates. 1.3 Test Method B (Sections 12 to 21)--ICP is used to analyze a sample that is decomposed with acid. 1.4 The concentration ranges covered by these test methods are determined by the sensitivity of the instruments, the amount of sample taken for analysis, and the dilution volume. A specific statement is given in Note 4. Typically, the low concentration limits are a few tenths of a mg/kg. Precision data are provided for the concentration ranges specified in Section 20. 1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.6 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not exact equivalents; therefore, each system shall be used independently of the other. 1.7 This standard does not purport to address all of the
3. Summary of Test Methods 3.1 Test Method A--Approximately 10 g of the sample are dissolved in an organic solvent (Warning--see Note 1) to give a specimen solution containing 10 % (m/m) of sample. The solution is nebulized into the plasma, and the intensities of the emitted light at wavelengths characteristic of the analytes are measured sequentially or simultaneously. The intensities are related to concentrations by the appropriate use of calibration data. NOTE 1: W a r n i n g - - C o m b u s t i b l e . Vapor is harmful.
3.2 Test Method B--One to 20 g of sample are weighed into a beaker and decomposed with concentrated sulfuric acid (Warningmsee Note 2) by heating to dryness. Great care must be used in this decomposition because the acid fumes are corrosive and the mixture is potentially flammable. The residual carbon is burned offby heating at 525"C in a muffle furnace. The inorganic residue is digested with nitric acid (Warning--see Note 2), evaporated to incipient dryness, dissolved in dilute nitric acid, and made up to volume. The solution is nebulized into the plasma of an atomic emission spectrometer. The intensities of light emitted at characteristic wavelengths of the metals are measured sequentially or simultaneously. These intensities are related to concentrations by the appropriate use of calibration data.
safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
NOTE 2: W a r n i n g - - P o i s o n . Causes severe burns. Harmful or fatal if swallowed or inhaled.
. Referenced Documents
4. Significance and Use 4.1 These test methods cover, in single procedures, the determination of Ni, V, and Fe in crude oils and residual oils. These test methods complement Test Method D 1548, which covers only the determination of vanadium. 4.2 When fuels are combusted, vanadium present in the fuel can form corrosive compounds. The value of crude oils can be determined, in part, by the concentrations of nickel, vanadium, and iron. Nickel and vanadium, present at trace levels in petroleum fractions, can deactivate catalysts during processing. These test methods provide a means of determining the concentrations of nickel, vanadium, and iron.
2.1 A S T M Standards: D 1193 Specification for Reagent Water2 D 1548 Test Method for Vanadium in Navy Special Fuel Oil 3 D4057 Practice for Manual Sampling of Petroleum and Petroleum Products4 This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.03.0B on Spectrometric Methods. Current edition approved Oct. 10, 1995. Published December 1995. Originally published as D 5708 - 95. Last previous edition D 5708 - 95. 2 Annual Book of ASTM Standards, Vol I 1.01. 3 Annual Book of ASTM Standards, Vol 05.01. 4 Annual Book of ASTM Standards, Vol 05.02.
s Annual Book of ASTM Standards, Vol 05.03.
948
v sz0a TABLE 1 Elements Determined and Suggested Wavelengths NOTE-- These wavelengths are suggestions and do not represent all possible choices. A
5. Purity of Reagents 5.1 Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where such specifications are available. 6 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 5.2 When determining metals at concentrations less than 1 mg/kg, use ultra-pure reagents. 5.3 Purity of Water--Unless otherwise indicated, reference to water shall be understood to mean reagent water conforming to Type II of Specification D 1193.
Element
Wavelength, nm
Iron
259.94, 238.20 231.60, 216.56 292.40, 310.22
Nickel Vanadium
A Winge, R. K., Fassel, V. A., Peterson, V. J., and Floyd, M. A., Inductively Coupled Plasma Atomic Emission Spectroscopy: An Atlas of Spectral Information, Elsevier, NY, 1985.
contains low concentrations (typically, a few mg/kg) of the analytes. 8.2 Mineral Oil--A high-purity oil such as U.S.P. white oil. 8.30rganometallic Standards--Pre-prepared multi-element concentrates containing 100 mg/kg concentrations of each element are satisfactory)
6. Sampling and Sample Handling 6.1 The objective of sampling is to obtain a sample for testing purposes that is representative of the entire quantity. Thus, take samples in accordance with the instructions in Practice D 4057. Do not fill the sample container more than two-thirds full. 6.2 Prior to weighing, stir the sample and manually shake the sample container. If the sample does not readily flow at room temperature, heat the sample in a drying oven at 80"C or at another safe temperature. TEST METHOD A-ICP WITH AN ORGANIC SOLVENT SPECIMEN SOLUTION
7. Apparatus
7.1 Inductively Coupled Plasma Atomic Emission Spectrometer-Either a sequential or simultaneous spectrometer, equipped with a quartz torch and radio-frequency generator to form and sustain the plasma, is suitable. 7.2 NebufizerBThe use of a high-solids nebulizer is optional but strongly recommended. This type of nebulizer minimizes the probability of clogging. A concentric glass nebulizer can also be used. 7.3 Peristaltic Pump--This pump is required for nonaspirating nebulizers and optional for aspirating nebulizers. The pump must achieve a flow rate in the range of 0.5 to 3 mL/min. The pump tubing must be able to withstand at least a 6 h exposure to the solvent. Fluoroelastomer copolymer tubing is recommended. 7 7.4 Specimen Solution Containers, glass or plastic vials or bottles with screw caps and a capacity of between 50 to 100 mL. One hundred millilitre glass bottles are satisfactory.
9. Preparation of Standards and Specimens 9.1 Blank--Prepare a blank by diluting mineral oil with dilution solvent. The concentration of mineral oil must be 10 % (m/m). Mix well. 9.2 Check StandardBUsing organometallic standards, mineral oil, and dilution solvent, prepare a check standard to contain analyte concentrations approximately the same as expected in the specimens. The concentration of oil in the check standard must be 10 % (m/m). 9.3 Test Specimen~Weigh a portion of well-mixed sample into a container and add sufficient solvent to achieve a sample concentration of 10 % (m/m). Mix well. 9.4 Working Standard--Prepare an instrument calibration standard that contains 10 mg/kg each of vanadium, nickel, and iron. Combine the organometallic standard, dilution solvent and, if necessary, mineral oil so that the oil content of the calibration standard is 10 % (m/m). 10. Preparation of Apparatus 10.1 Consult the manufacturer's instructions for the operation of the ICP instrument. This test method assumes that good operating procedures are followed. Design differences between instruments make it impractial to specify required parameters. 10.2 Assign the appropriate operating parameters to the instrument taskfile so that the desired analytes can be determined. Parameters include: (1) element, (2) analytical wavelength, (3) background correction wavelengths (optional), (4) interelement correction factors (refer to 10.3), (5) integration time of 1 to 10 s, (6) two to five consecutive repeat integrations. Suggested wavelengths are listed in Table 1. 10.3 Spectral InterferencesBCheck all spectral interferences expected for the analytes. If interference corrections are necessary, follow the manufacturer's operating guide to develop and apply correction factors. 10.3.1 Spectral interferences can usually be avoided by judicious choice of analytical wavelengths. If spectral inter-
8. Reagents 8.1 Dilution Solvent~Mixed xylenes, o-xylene, tetralin and mixed paraffin-aromatic solvents are satisfactory. Solvent purity can affect analytical accuracy when the sample 6 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards fi~r Laboratory Clwmicals, BDH Ltd., Poole, Dorset, U.K., and the Uniled States Pharmacopeia and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD. Viton (a trademark owned by E. I. duPont de Nemours) tubing has been Ibund satisPaclory and is available from Gilson Medical Electronics, Inc., Mtddleton, Wl 53562. An equivalent can be used.
a Standards from the following source have been found satisfactory for this purposc--Conoco, Inc., Conostan Division, P. O. Box 1269, Ponca City, OK 74603.
949
~
D 5708
ferences cannot be avoided, the necessary corrections should be made using the computer software supplied by the instrument manufacturer or by using the empirical method described in Test Method D 5185. 10.4 Consult the instrument manufacturer's instructions for operating the instrument with organic solvents. 10.5 During instrument warm-up, nebulize the blank solution. Inspect the torch for carbon build-up. When carbon build-up occurs, replace the torch and adjust the operating conditions to correct the problem. 10.5.1 Carbon build-up within the torch can be caused by improperly adjusted argon flow rates, improper solution flow rates, and positioning the torch injector tube too close to the load coil. Carbon deposits can invalidate a calibration and extinguish the plasma.
Infrared Lamp
Vycor Vessel .ah
~
.....,
11. Calibration and Analysis 11.1 Using the blank and working standard, perform a two-point calibration at the beginning of the analysis of each batch of specimens. Additional working standards can be used, if desired. 11.2 Use the check standard to determine if the calibration for each analyte is accurate. When the result obtained on the check standard is not within =1=5% of the expected concentration for each analyte, take corrective action and repeat the calibration. 11.3 Analyze the specimens in the same manner as the calibration standards (that is, same integration time, plasma conditions, and so forth). Calculate concentrations by multiplying the concentration determined for the test specimen solution by the dilution factor. Calculation of concentrations can be performed manually or by computer when such a feature is available. 11.4 When the measured intensities for the test specimen solution exceed the corresponding intensities for the working standard, either ensure that the calibration curve is linear to the concentration of the element in the test specimen solution or dilute the test specimen solution with the blank solution and reanalyze. 11.5 Analyze the check standard after every fifth specimen. If any result is not within 5 % of the expected concentration, take corrective action, repeat the calibration, and reanalyze the specimen solutions back to the previous acceptable check standard analysis. 11.6 The use of spectral background correction is highly recommended, particularly when the test specimen solutions contain low concentrations of the analytes (typically less than 1 mg/kg). When concentrations are low, background changes, which can result from variability in the compositions of test specimen solutions, can affect the accuracy of the analysis. Background correction minimizes errors due to variable background intensities. TEST METHOD Bm ICP AFTER ACID DECOMPOSITION OF SAMPLE
12. Apparatus 12.1 Refer to 7.1 to 7.4. 12.2 Sample Decomposition Apparatus (optional)--This apparatus is shown in Fig. I. It consists of a high-silica or borosilicate 400-mL beaker for the specimen, an air bath (Fig. 2) that rests on a hot plate, and a 250-watt infrared 950
m
Air Bath
Sample
.
J
~Hot FIG. 1
Plate
DecompositionApparatus
lamp supported 1 in. above the air bath. A variable transformer controls the voltage applied to the lamp. 12.3 Glassware, high-silica or borosilicate 400-mL beakers, volumetric flasks of various capacities, and pipettes of various capacities. When determining concentrations below l mg/kg, all glassware must be thoroughly cleaned and rinsed with water. 12.4 Electric Muffle Furnace, capable of maintaining 525 + 25"C and sufficiently large to accommodate 400-mL beakers. The capability of an oxygen bleed is advantageous and optional. 12.5 Steam Bath (optional). 12.6 Temperature Controlled Hot Plate (optional).
13. Reagents 13.1 Aqueous Standard Solutions, individual aqueous standards with 1000 mg/L concentrations of vanadium, nickel, and iron. 13.2 Nitric Acid, concentrated nitric acid, HNO3. 13.3 Nitric Acid (I +/)--Carefully add, with stirring, one volume of concentrated nitric acid to one volume of water. 13.4 Dilute Nitric Acid (19 + /)--Carefully add, with stirring, one volume of concentrated nitric acid to 19 volumes of water. 13.5 Sulfuric Acid, concentrated sulfuric acid, H2SO4. 14. Preparation of Standards 14.1 Blank Standard--Dilute (19 + 1) nitric acid. 14.2 Multi-element StandardmUsing the aqueous standard solutions, prepare a multi-element standard containing 100 mg/L each of vanadium, nickel, and iron. 14.3 Working Standard--Dilute the multi-element standard ten-fold with dilute nitric acid. 14.4 Check Standards--Prepare calibration check standards in the same way as the working standard and at analyte concentrations that are typical of the samples being analyzed.
o sro8 tion. Perform all steps specified in this section. NOTE 4: Caution--Reagent blanks are critical when determining concentrations below I mg/kg. To simplify the analysis, use the same volume of acid and the same dilutions as used for the samples. For example, if 20 g of sample is being decomposed, use 10 mL of sulfuric acid for the reagent blank. 15.3 The use of the air bath apparatus (Fig. 2) is optional. Place the beaker in the air bath, which is located in a hood. The hot plate is off at this time. Heat gently from the top with the infrared lamp (Fig. 1) while stirring the specimen with a glass rod. As decomposition proceeds (indicated by a frothing and foaming), control the heat of the infrared lamp to maintain steady evolution of fumes. Give constant attention to each sample mixture until all risk of spattering and foaming is past. Then, gradually increase the temperatures of both the hot plate and lamp until the sample is reduced to a carbonaceous ash. 15.4 If the air bath apparatus is not used, heat the sample and acid on a temperature controlled hot plate. As described in 15.3, monitor the decomposition reaction and adjust the temperature of the hot plate accordingly. NOTE 5: Precaution--Hot, fuming, concentrated sulfuric acid is a very strong oxidizing acid. The analyst should work in a well-ventilated hood and wear rubber glovesand a suitable face shield to protect against spattering acid. 15.5 Place the sample in a muffle furnace maintained at 525 + 25"C. Optionally, introduce a gentle stream of oxygen into the furnace to expedite oxidation. Continue to heat until the carbon is completely removed. 15.6 Dissolve the inorganic residue by washing down the wall of the beaker with about 10 m L of 1+1 HNO 3. Digest on a steam bath for 15 to 30 min. Transfer to a hot plate and gently evaporate to incipient dryness. 15.7 Wash down the wall of the beaker with about 10 m L of dilute nitric acid. Digest on the steam bath until all salts are dissolved. Allow to cool. Transfer quantitatively to a volumetric flask of suitable volume and make up to volume with dilute nitric acid. This is the specimen solution.
1 t!
6T
==..~1 v
1 "--~ 3 lq
7 tw
3-g 5"
l
j-
~ _ 1 ! ~ 2"
_tq
\_. 1" 4 Fig_
NOTE--All parts are 16-gage (0.060 in., 1.5 mm) aluminum. All dimensions are in inches. Metric Equivalents in.
mm
in.
mm
1 11/2 2 3i/le
25.4 38.1 50.8 77.8
3% 5 61/2
98.4 127 165.1
FIG. 2
16. Preparation of Apparatus 16.1 Refer to 10.1 to 10.3. 17. Calibration and Analysis 17.1 Refer to Section 11. 17.2 Analyze the reagent blank (refer to 15.2) and correct the results obtained on the test specimen solutions by subtracting the reagent blank results.
Air Bath
15. Preparation of Test Specimens 15.1 Into a beaker, weigh an amount of sample estimated to contain between 0.0025 and 0.12 mg of each metal to be determined. A typical mass is 10 g. Add 0.5 mL of H2SO4 for each gram of sample. NOTE 3mlf it is desirable to extend the lower concentration limits of the method, it is recommendedthat the decompositions be done in 10-g increments up to a maximum of 100 g. It is not necessaryto destroy all the organic matter each time before adding additional amounts of sample and acid. When it is desirable to determine higher concentrations, reduce the sample size accordingly. 15.2 At the same time, prepare reagent blanks using the same amount of sulfuric acid as used for sample decomposi-
18. Calculations 18.1 For Test Method A, calculate the concentration of each analyte in the sample using the following equation: analyte concentration, mg/kg = C × F (I) where: C = concentration of the analyte in the specimen solution, mg/kg, and F = dilution factor. 18.2 For Test Method B, calculate the concentration of each analyte in the sample using the following equation: analyte concentration, mg/kg ffi (C x V x F)/W (2) where:
951
q~) D 5708 TABLE 4 Reproducibility NOTE~X -- mean ¢ortcerttratJon,mg/kg.
TABLE 2 Repeatability NOTE~X = mean concentration, mg/kg. Element
Concentration Range, rnglkg
Vanadium
50-500
Test Method A A
0.07X °.u 0.02X 1.1 0.01X 1.s
B
0.02X 1.a
A B
0.22X°.a° 0.23X °.aT
B
Nickel
10-100
Iron
1-10
TABLE 3
Element Vanadium Nickel Iron
Element
Repeatability, rng/kg
Vanadium
10
50
A
2.2
B
1.5
A B A B
0.22 0.23
0.20 0.32 0.44 1.08
1.6 2.2
500
4.0 3.2 4.0 5.0
17 19
A
10-100
Iron
TABLE 5
100
50-500
Nickel
Concentration 1
Test Method
1-10
A B
0.05X ~.a
A B
0.68X°.~ 0.91Xo,sl
Calculated Reproducibility ( m g l k g ) at Selected Conoentmtions (mglkg) Concentration
Element
Test Method
50
100
500
Vanadium
A
8.9
19
B
7.4
16
112 93
15 20
Nickel Iron
1
10
A
2.5
8.7
B
1.0
B.1
A B
C ffi concentration of the analyte in the specimen solution (corrected for the concentration determined in the reagent blank), mg/L V = volume of the specimen solution, mL, F = dilution factor, and W= sample mass, g.
Reproducibility, mg/kg 0.12X 1.1 0.10X 1.1 0.41X°.7"
B
Calculated Repeatability ( m g / k g ) at Selected Concentrations ( m g l k g ) Test Method
Concentration Range, mg/kg
0.68 0.91
1.5 2.9
background correction. Seven samples (four residual oils and three crude oils) comprised the test set. One residual oil was NIST SRM 1618 m, and one crude oil was NIST RM 8505. I° 20.1.1 Repeatability--The difference between two test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test materials would, in the long run, in the normal and correct operation of the test method, exceed the values in Tables 2 and 3 only in one case in twenty. 20.1.2 Reproducibility--The difference between two single and independent results, obtained by different operators working in different laboratories on identical test materials would, in the long run, in the normal and correct operation of the test method, exceed the values in Tables 4 and 5 only in one case in twenty. 20.2 Bias--Bias was evaluated from results obtained on two NIST samples. For Test Methods A and B, the means of the reported values for V and Ni do not differ from the corresponding expected values by more than the repeatability of the test method. Standard reference materials for Fe are not available, so bias was not determined.
19. Report 19.1 Report concentrations in mg/kg to three significant figures.
20. Precision and Bias 9 20.1 PrecisionmThe precision of these test methods was determined by statistical analysis of interlaboratory test results. For Test Method A, eleven cooperators participated in the interlaboratory study. Mixed xylenes, o-xylene, and tetralin were successfully used as dilution solvents. One cooperator noted that when kerosine was used, a precipitate developed in several minutes. All cooperators used a peristaltic pump. Approximately half of the cooperators used a high-solids nebulizer. Approximately half of the cooperators used background correction. For Test Method B, eight cooperators participated in the interlaboratory study. All labs but one used a peristaltic pump. Most labs did not use a high-solids nebulizer. Approximately half of the labs used
21. Keywords 21.1 emission spectrometry; ICP; inductively coupled plasma atomic emission spectrometry; iron; nickel; vanadium
9 Interlaboratory study data are available from ASTM Headquarters. Request RR:D02-135 I.
'OAva/lablc from the National Institute of Standards and Technology, Gaithersburg, MD 20899.
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expresNy advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, ere entirely their own reepousitNIIty. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years a M it not revised, either reapproved or withdrawn. "Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received • fair hearing you should make your views known to the ASTM Committee on Standards, 100 Berr Harbor Drive, West Conshohocken, PA 19428.
952
(~~ll~ Designation: D 5713 - 96 Standard Test Method for Analysis of High Purity Benzene for Cyclohexane Feedstock by Capillary Gas Chromatography 1 This standard is issued under the fixed designation D 5713; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or rcapproval.
of the internal standard, and using a response factor of 1.00 for nonaromatic impurities and the amount of internal standard added, the concentrations of the impurities are calculated. The benzene content is obtained by subtracting the total amount of all impurities from 100.00.
1. Scope 1.1 This test method covers the determination of specific impurities in, and the purity of benzene for cyclohexane feedstock by gas chromatography. It is applicable to benzene in the range from 99 to 100 % purity and to impurities at concentrations of 2 to l0 000 mg/kg. 1.2 The following applies to all specified limits in this test method: for purposes of determining conformance with this test method, an observed value or a calculated value shall be rounded off "to the nearest unit" in the last right-hand digit used in expressing the specification limit, in accordance with the rounding-off method of Practice E 29. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement, see Section 7 and Note 1.
4. Significance and Use 4.1 This test method is designed to obtain benzene purity on the basis of impurities normally present in benzene and may be used for final product inspections and process control. 4.2 This test method will detect the following impurities: toluene, methylcyclopentane, n-hexane, 2-methylhexane, cyclohexane, cyclopentane, 2-methylpentane, 2,3-dimethylpentane, 3-methylhexane, n-heptane, methylcyclohexane, ethylcyclopentane, 2,4-dimethylhexane, trimethylpentane, and others where specifc impurity standards are available. Absolute purity cannot be accurately determined if unknown impurities are present.
2. Referenced Documents
5. Apparatus 5. l Gas Chromatograph--Any gas chromatograph having a temperature programmable oven, flame ionization detector and a splitter injector suitable for use with a fused silica capillary column may be used, provided the system has sufficient sensitivity that will give a minimum peak height of 3 times the background noise for 2 mg/kg of an impurity when operated at recommended conditions. 5.2 Column--Fused silica capillary columns have been found to be satisfactory. An example is 50 m of 0.20-ram inside diameter fused silica capillary internally coated to a film thickness of 0.50 ~tm with cross-linked methyl silicone (see Table l for parameters). Other columns may be used after it has been established that such a column is capable of separating all major impurities (for example, compounds listed in 4.2) and the internal standard from the benzene under operating conditions appropriate for the column. The column must give satisfactory resolution (distance from the valley between the peaks is not greater than 50 % of the peak heights of the impurity) of cyclohexane from benzene as well as other impurity peaks. A poorly resolved peak, such as cyclohexane, will often require a tangent skim from the neighboring peak. 5.3 Electronic Integration, with tangent skim capabilities is recommended. 5.4 Vial. 5.5 Microsyringes, assorted volumes.
2.1 A S T M Standards: D3437 Practice for Sampling and Handling Cyclic Products2 E 29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications 3 E 260 Practice for Packed Column Gas Chromatography3 E 355 Practices for Gas Chromatography Terms and Relationships3 E 1510 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs3 2.2 Other Document: OSHA Regulations, 29 CFR, paragraphs 1910.1000 and 1910.12004 3. Summary of Test Method 3.1 In this test method, the chromatogram peak area for each impurity is compared to the peak area of the internal standard (n-octane or other suitable known) added to the sample. From the response factor of toluene relative to that This test method is under the jurisdiction of ASTM Committee D-16 on Aromatic Hydrocarbon and Related Chemicals and is the direct responsibility of Subcommittee DI6.0A on Benzene, Toluene, Xylenes, Cyclohexane, and Their Derivatives. Current edition approved Feb. 10, 1996. Published March 1996. Originally published as D 5713 - 95. Last previous edition D 5713 - 95 ° . 2 Annual Book of ASTM Standards, Vol 06.04. 3 Annual Book of ASTM Standards, Vol 14.02. 4 Available from the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402.
6. Reagents and Materials 6. l Carrier Gas--a carrier gas (minimum purity of 99.95 953
~ TABLE 1
D 5713
Instrument Typical Parameters
Carder gas Unear velocity at 40°C, cm/s Detector Detector temperature, °C Injection port temperature, °C Split ratio Split flow, mL/min Column Initial column temperature, *C Initial time, mln Programming rate Final temperature, *C Final time, rain Sample size, ~L
9. Procedure 9.1 Follow the manufacturer's instructions for mounting the column into the chromatograph and adjusting the instrument to the conditions described in Table 1. Allow sufficient time for the equipment to reach equilibrium. See Practices E 260, E 355 and E 1510 for additional information on gas chromatography precedures, terminology, and column installation. 9.2 Transfer approximately 10 g of the sample to be analyzed to a tared vial and weigh to the nearest 0.1 mg. (Make sure that the sample is deposited in the center of the vial with a Pasteur pipet so that the liquid does not contact the neck.) 9.3 Add approximately 0.1 g of n-octane internal standard using a Pasteur pipet and quickly reweigh to the nearest 0.1 mg. (The internal standard is added to the vial while on the balance pan and deposited into the center of the liquid--not on the side of the vial.) 9.4 Cap the mixture and mix by inverting several times. 9.5 Inject 1.2 p.l of the sample containing internal standard and immediately start the recorder, temperature programming sequence, and integrator. 9.6 Determine the areas of all the impurity peaks and n-octane. Identify the specific impurities by comparing the chromatogram obtained to the typical chromatogram shown on Fig. 1 (unidentified impurities are summed and reported as a composite).
hydrogen 40 flame ionization 250°C 250°C 40:1 60 50 m by 0.20 mm ID by 0.5 ixm bonded methyl silicone fused silica capillary 40 17 10°C/min 250°C 10 1.2
% mol) appropriate to the type of detector used should be employed. NOTE l--Precaution: If hydrogen is used as the carrier gas, take special safety precautions to ensure that the system is free of leaks and that the effluent is properly vented or burned.
6.2 Hydrogen and Air for the flame ionization detector (FID). 6.3 n-octane, 99.0 % minimum purity, or other internal standard, such as/so-octane, previously analyzed to be free of compounds coeluting with impurities in the sample.
7. Hazards 7.1 Consult current OSHA regulations, suppliers' Material Safety Data Sheets, and local regulations for all materials used in this test method.
10. Calculation 10.1 Measure the areas of all peaks, including the internal standard, except the benzene peak. 10.2 Calculate the weight to milligram per kilogram-mg/kg of the individual impurities, C, as follows:
8. Sampling 8.1 Sample in accordance with Practice D 3437.
G = lO6
BDF GH
b
, I
!i ,,ii !
=-:
I 0 4 Retention "lime, Minutes PIG. 1
I 12
ill
I
I
I
I
16
20
24
28
High Purity Benzene--Typical (See Table 1)
954
Chromatogram
30
~
D 5713 TABLE 2 Intermediate Precision and Reproducibility
where: B = peak area of a specific impurity or group of impurities, D = response factor, (see 10.3), F = mass of n-octane added to the sample, g, G = peak area of the n-octane, H = weight of sample before addition of n-octane, g, and 106 = factor to convert to weight-mg/kg 10.3 A response factor of 1.000 should be used for all hydrocarbon impurities except toluene which will be 0.935. 10.4 Calculate the benzene content by subtracting the sum of the impurities from 100.000. Benzene weight % = 100.000 - (sum of impurities in weight %). Total impurities are converted from mg/kg to weight percent by multiplying by 0.0001%.
Component
Average Concentrationppm Weight %
intermediate Precision
Reproducil~lity
Benzene
99.96 99.97 99,96
0.006 0.007 0.008
0.022 0.020 0.025
Methylcyclopentane
104 43 54
8.3 12.2 2.5
27.9 19.4 15.1
Toluene
64 63 28
5.1 3.0 1.8
22.0 16.6 9.1
Methylcyctohexane
132 43 79
7.4 1.4 3.2
34.8 5.4 17.0
Methylcyclohexane + Toluene
196 106 106
7.9 12.9 4.4
54.9 33.6 20.4
11. Report
n-Hexane
11.1 Report the concentration of impurities to the nearest mg/kg and the benzene content to the nearest 0.01%. For conversion purposes, 1 mg/kg equals 0.0001%.
4 3 2
2.2 1.5 1.8
3.7 2.2 2.5
n-Heptane
6 16 15
2.7 1.5 4.0
11.1 5.6 23.4
Ethylcyclopentane
7
1.8
3,7
6
1.9
11.0
11
1.5
6.1
99 107 185
22.5 44.6 55.5
163,0 190.6 233.0
12. Precision and Bias s 12.1 Precision--The following criteria should be used to judge the acceptability (95 % probability level) of results obtained by this test method. The criteria in Table 2 were derived from an interlaboratory study between six laboratories. Three samples were analyzed in duplicate on two days.
Total Other impurities
differ by more than the amount shown in Table 2. On the basis of test error alone, the difference between two test results obtained in different laboratories on the same material will be expected to exceed this value only 5 % of the time. 12.2 Bias--Since there is no accepted reference material suitable for determining the bias for the procedure in this test method for measuring specific impurities, bias has not been determined.
12. I. 1 Intermediate Precision (formerly Repeatability)Results in the same laboratory should not be considered suspect unless they differ by more than the amounts shown in Table 2. On the basis of test error alone, the difference between two results obtained in the same laboratory on the same material will be expected to exceed this value only 5 % of the time. 12.1.1 Repeatability--Results submitted by each of two laboratories should not be considered suspect unless they
13. Keywords 5 Supporting data are available from ASTM Headquarters. Request RR: Dlr-1018.
13.1 benzene; cyclohexane feedstock; impurities
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohockan, PA 19428.
955
(~T~ Designation: D 5762 - 95 Standard Test Method for Nitrogen in Petroleum and Petroleum Products by Boat-Inlet Chemiluminescence Th~s standard ~s issued under the fixed designation D 5762; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
1. Scope I. 1 This test method covers the determination of nitrogen in liquid hydrocarbons including petroleum process streams and lubricating oils in the concentration range from 40 to 10 000 Ixg/g nitrogen. For light hydrocarbons containing less than 100 ixg/g nitrogen, Test Method D 4629 can be more appropriate. 1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. Referenced Documents
2.1 A S T M Standards: D 4052 Test Method for Density and Relative Density of Liquids by Digital Density Meter a D4057 Practice for Manual Sampling of Petroleum and Petroleum Products 2 D 4177 Practice for Automatic Sampling of Petroleum and Petroleum Products z D 4629 Test Method for Trace Nitrogen in Liquid Petroleum Hydrocarbons by Syringe/Inlet Oxidative Combustion and Chemiluminescence Detection 2 3. Summary of Test Method 3.1 A hydrocarbon sample is placed on a sample boat at room temperature. The sample and boat are advanced into a high-temperature combustion tube where the nitrogen is oxidized to nitric oxide (NO) in an oxygen atmosphere. The NO contacts ozone and is converted to excited nitrogen dioxide (NO2). The light emitted as the excited NO2 decays is detected by a photomultiplier tube and the resulting signal is a measure of the nitrogen contained in the sample. 4. Significance and Use 4.1 Many nitrogen compounds can contaminate refinery catalysts. They tend to be the most difficult class of compounds to hydrogenate so the nitrogen content remaining in the product of a hydrotreator is a measure of the effectiveThis lest method is under the jurisdlclmn of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee I)02.03 on Elemental Analysis ('urrcnt cdtlkm appuoved Aug. 15, 1995. Puhlished October 1995. 2 Annual Book o~ ASTM Standards, Vol 05,02.
956
ness of the hydrotreating process. In lubricating oils the concentration of nitrogen is a measure of the presence of nitrogen containing additives. This test method is intended for use in plant control and in research. 5. Apparatus 5. l Boat Inlet System, capable of being sealed to the inlet of the combustion tube and swept with inert gas. The boats are fabricated from platinum or quartz. To aid quantitative liquid injection, add a small piece of quartz wool to the boat. The boat drive mechanism should be able to fully insert the boat into the furnace tube inlet section. A drive mechanism which advances and withdraws the sample boat into and out of the furnace at a controlled and repeatable rate is required. 5.2 Chemiluminescence Detector, capable of measuring light emitted from the reaction between nitric oxide and ozone, and containing a variable attenuation amplifier, integrator, and readout. 5.3 Combustion Tube, fabricated from quartz. The inlet end of the tube shall be large enough to accept the sample boat and have side arms for introduction of oxygen and inert gas. The construction is such that the carder gases sweep the inlet zone transporting all of the volatilized sample into a high-temperature oxidation zone. The oxidation section should be large enough to ensure complete oxidation of the sample. Combustion tubes recommended for the two furnaces in 5.5.1 and 5.5.2 are described in 5.3.1 and 5.3.2. Other configurations are acceptable if precision and bias are not degraded. 5.3. l Quartz combustion tube for use with the single-zone furnace is illustrated in Fig. 1. A water-jacket around the inlet section can be used to cool the boat prior to sample injection. 5.3.2 Quartz combustion tube for use with the two-zone furnace is illustrated in Fig. 2. The outlet end of the pyrolysis tube is constructed to hold a removable quartz insert tube. The removable quartz insert tube is packed with copper oxide and silver wool, which can aid in completing oxidation. 5.4 Drier Tube, for the removal of water vapor. The reaction products include water vapor that shall be eliminated prior to measurement by the detector. This can be accomplished with a magnesium perchlorate, Mg(CIO4).~, scrubber, a membrane drying tube permeation drier, or a chilled dehumidifier assembly. 5.5 Furnace, Electric, held at a temperature sufficient to pyrolyze all of the sample and oxidize the nitrogen to NO. Either of the following furnace designs can be used. 5.5.1 Single-zone tube furnace with temperature controller capable of maintaining a furnace temperature of
(@) D 5762 892mm 257rnrn
6turn O 0
× 2turn ID
12 r a m
35mm
,,f
50ram
~l 60ram
25ram FIG. 1
6r-rim OD x 2 r a m
ID
Quartz Combustion Tube (Single-Zone Furnace)
f E
/ Jl120~n
130ran
40mm
90mm 160mm 200mm FIG. 2
Quartz Combustion Tube (Two-Zone Furnace)
reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 6.2 Acridine, CI3H9N, molecular weight 179.21, 7.82 mass % nitrogen.
1100°C. Included in the furnace assembly are needle valves for gas flow control. 5.5.2 Two-zone tube furnace with temperature controllers capable of maintaining the temperature of each furnace zone independently to 1050°C. Included in the furnace assembly are flow restrictors for gas flow control. 5.6 Microlitre Syringe, of 5 or 10-gL capacity, capable of accurately delivering microlitre quantities. 5.7 Ozone Generator, to supply ozone to the detector reaction cell. 5.8 Recorder (Optional), for display of chemiluminescence detector signal.
NOTE 1: W a r n i n g - - I r r i t a n t .
6.3 Cupric Oxide Wire, CuO, as recommended by the instrument manufacturer. 6.4 Inert Gas--Argon or Helium only, high-purity grade (that is, chromatographic or zero grade), 99.998 % minimum purity, 5 ppm maximum moisture. 6.5 Anhydrous Magnesium Perch/orate, Mg(CIO4)> for drying products of combustion (if permeation drier or chilled drier is not used).
6. Reagents and Materials
NOTE 2: Warning--Strong oxidizer, irritant.
6.1 Purity q[Reagents--Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where such specifications are available? Other grades may be used, provided it is first ascertained that the
6.6 Nitrogen Stock Solution, 500 ng nitrogen/laL--Accurately weigh (to the nearest 0.1 rag) approximately 0.64 g of acridine into a tared 100-mL volumetric flask. Add xylene to dissolve, then dilute to volume with xylene. Calculate the nitrogen content of the stock solution to the nearest milligram of nitrogen per litre. This stock can be further diluted to desired nitrogen concentrations.
"~Reagent Chemicals. Amertcan Cbemwa/ Sactety Speci[icattons, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards .[br Laboratory ('hemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pbarmacopeia and Nattomd I.'ormalarv, U.S. Pharmaceutical Conventmn, Inc. (USPC), Rockvlllc, MD
NOTE 3: Caution--Remake standard solutions on a regular basis depending upon frequency of use and age. Typically,standards have a useful life of approximatelythree months. 6.7 Oxygen, high-purity grade (that is, chromatographic 957
o 5782 9. Calibration and Standardization 9.1 Prepare calibration standards containing 1, 5, 10, 50, and 100 ng nitrogen/laL in xylene by volumetric dilution of the 500-rig nitrogen/IxL nitrogen stock solution. 9.2 Five microlitres of the material to be analyzed (see Note 10) shall be quantitatively placed in the sample boat for measurement of chemiluminescence response. There are two alternative injection procedures available, the volumetric and the gravimetric procedures.
or zero grade), 99.75 % minimum purity, 5 ppm maximum moisture, dried over molecular sieves. NOTI'."4: WarningmVigorously acceleratescombustion. 6.8 Quartz Wool. 6.9 Silver Wool, as recommended by the instrument manufacturer. 6.10 Xylene. NOTE 5: Warning--Flammable, health hazard.
NOTE 10--The formation of NO and NO2 from oxidative combustion of nitrogen containing hydrocarbons is dependent on combustion conditions such as temperature and oxygen concentration. Injection of a constant solution volume, and dilution of all test specimens and standards with a common solvent, maintain consistent combustion conditions for test specimens and standards.
7. Sampling 7.1 Obtain a test sample in accordance with Practice D 4057 or D 4177. NOTE 6: Warning--Samples that are collected at temperatures below room temperature can undergo expansion at laboratory temperatures and rupture the container. For such samples, do not fill the container to the top. Leave sufficient air space above the sample to allow room for expansion. Norr.. 7: Caution--To minimize loss of volatile components which can be present in some test samples, do not uncover any longer than necessary. Test samples should be analyzed as soon as possible after taking from bulk supplies to prevent loss of nitrogen or contamination due to exposure or contact with sample container.
9.2.1 For volumetric measurement of the material by microlitre syringe, flush the microlitre syringe several times with the material, discarding the flushed liquid each time. Fill the 10-p.L syringe to the 5-1aL level. Retract the plunger so that the lower liquid meniscus falls on the 10 % scale mark. When bubbles are present within the liquid column, flush the syringe and withdraw a new aliquot of the liquid. Record the volume of liquid in the syringe. Immediately inject the liquid into the boat, being careful to displace the last drop by touching the edge of the boat, or the quartz wool if present, with the syringe needle. After the injection, again retract the plunger so that the lower liquid meniscus falls on the 10 % scale mark and record the volume of liquid in the syringe. The difference between the two volume readings is the volume of liquid injected.
7.2 If the test sample is not used immediately, then thoroughly mix it in its container prior to taking a test specimen. Some test samples require heating in order to thoroughly homogenize. 8. Preparation of Apparatus 8.1 Assemble apparatus in accordance with the manufacturer's instructions. 8.2 Adjust the oxygen flow for the ozone generator in accordance with the manufacturer's instructions. Adjust the combustion tube gas flows and the pyrolysis temperature to the desired operating conditions using the following guidelines for each furnace type.
NOTE I l--An automatic sampling and injection device can be used in place of the described manual injection procedure.
NOTE 8: Warning--Ozone is extremely toxic. Make sure that appropriate steps are taken to prevent discharge of ozone within the laboratory work area. 8.2.1 For the single-zone furnace, adjust the combustion tube gas flows to the following values: pyrolysis oxygen, 360 mL/min; inlet oxygen, 60 mL/min; and inert carrier inlet, 155 mL/min. Set the furnace temperature to 1100 _+ 25"C. Adjust the boat drive mechanism to obtain a drive rate of 150 __. 10 mm/min. Refer to the manufacturer's instructions for descriptions of these settings. 8.2.2 For the two-zone furnace, adjust the combustion tube gas flows to the following values: combustion oxygen, 165 mL/min; inlet inert carrier, 85 mL/min; and boat inert carrier, 50 mL/min. Set the inlet furnace temperature to 1050 + 25"C, and the outlet furnace temperature to 925 _.+ 25"C. Adjust the boat drive mechanism to obtain a drive rate of 150 :t: 10 mm/min (boat speed number 4). Refer to the manufacturer's instructions for the description of these settings. NOTE 9: Warning--High temperature is employed in this test method. Use flammable materials with care near the pyrolysis furnace. 8.3 Insert boat into furnace for a minimum of 2 min to remove any residual nitrogen species. 958
9.2.2 For gravimetric measurement of the solution, fill the syringe as indicated in 9.2.1. Weigh the microlitre syringe and its contents and record the mass to the nearest 0.01 mg. Immediately inject the liquid into the boat, being careful to displace the last drop by .touching the edge of the boat, or quartz wool if present, with the syringe needle. After the injection, remove the syringe and again weigh the syringe and its contents. Record the mass to the nearest 0.01 mg. The difference between the two weighings is the mass of liquid injected. The gravimetric procedure is more precise than the volumetric procedure, provided a balance with a precision of -0.01 mg is used. 9.3 Activate the boat drive mechanism to insert the boat into the furnace. The instrument baseline should remain stable until the boat approaches the furnace and volatilization of injected material begins. After the measurement is complete, retract the boat. The instrument baseline should reestablish before the boat has completely emerged from the furnace. Record the integrated chemiluminescence response. Allow the boat to cool for at least 1 min before the next injection. 9.4 Calibrate the instrument using one of the following two techniques. 9.4.1 Perform measurements for the calibration standards and blank using the procedure described in 9.2 and 9.3. Measure the calibration standards and blank three times each and determine the average integrated chemiluminescence response for each. Construct a curve plotting
t~) D 5762 average integrated detector response (y-axis) versus nanograms of nitrogen injected (x-axis). 9.4.2 If the system features an internal calibration routine, measure the calibration standards and blank three times each using the procedure described in 9.2 and 9.3. Calibrate the analyzer in accordance with the manufacturer's instructions using the average of the three measurements for each standard and blank. 9.5 If analyzer calibration is performed using only a subset of the calibration standards listed in 9.1, the calibration standards closest in concentration to the measured solution(s) must be included in the subset (that is, if the concentration of the test specimen solution is 20 ng nitrogenAtL, include the 10 and 50-ng nitrogen/laL standards in the calibration). System performance must be checked with the calibration standards at least once per day.
the residence time for the boat in the furnace if coke or soot is observed on the boat. Decrease the boat drive introduction rate if coke or soot is observed on the exit end of the combustion tube. Clean any coked or sooted parts. After any cleaning or adjustment, repeat instrument calibration prior to reanalysis of the test specimen. 11.5 Measure each test specimen solution three times and calculate the average chemiluminescence response. 12. Calculation 12.1 For analyzers calibrated using a standard curve, calculate the nitrogen content of the test specimen in micrograms per gram (lag/g) as follows: ( i - Y) Nitrogen, (p.g/g) = (I) SxMXKg or,
10. Quality Assurance 10.1 A sample of known nitrogen content will be run after each calibration. The sample can also be analyzed periodically throughout a series of analyses to check the functioning of the instrument and the validity of the calibration curve. This sample can be an National Institute for Standards and Tcchnology Standard Reference Material (SRM) material, an acridine in xylene standard prepared to have a nitrogen value not used to calibrate the instrument, or any other material that has been analyzed repeatedly such that sufficient data are available to determine a statistical mean. The rcsults of the analysis of the known sample will be within 10 % of the certified or accepted value for the operation and calibration of the instrument to be considered acceptable. If thc results are not within 10 % of the accepted value, perform appropriate corrective maintenance on the instrument and repeat the calibration procedure described in 9.4.
Nitrogen, (lag/g) =
( I - Y) Sx VxK v
(2)
where: D = density of test specimen solution, g/mL, 1 = average of integrated detector response for test specimen solution, counts (or found ng nitrogen), Kg = gravimetric dilution factor, mass of test specimen/ mass of test specimen and solvent, g/g, K,. = volumetric dilution factor, mass of test specimen/ volume of test specimen and solvent, g/mL, M = mass of test specimen solution injected, either measured directly or calculated from measured volume injected and density, V × D, mg, S = slope of standard curve, counts/ng nitrogen (or found ng nitrogen/ng nitrogen), V = volume of test specimen solution injected, either measured directly or calculated from measured mass injected and density, M/D, laL, and Y = y-intercept of standard curve, counts (or found ng nitrogen). 12.2 For analyzers calibrated using an internal calibration routine, calculate the nitrogen content of the test specimen in micrograms/gram (Ixg/g) as follows: I Nitrogen, (lag/g) = ~ (3) MxKs, or,
I 1. Procedure 11.1 Obtain a test specimen using the procedure described in Section 7. Prepare a test specimen solution by dilution of the test specimen in xylene. Use a dilution factor of at least 1:5 (see Note 10). The nitrogen concentration in the test specimen solution shall be less than the concentration of the highest standard used in calibration and greater than 3 ng nitrogen/laL. The dilution can be performed either on a weight or volume basis, 11.1.1 For gravimetric dilution, record the mass of the test specimen and the total mass of the test specimen and solvent. 11.1.2 For volumetric dilution, record the mass of the test specimen and the total volume of the test specimen and solvent. 11.2 Measure the chemiluminescence response for the test specimen solution using the procedure described in 9.2 and 9.3. 11.3 If the chemiluminescence response from the test specimen solution is greater than the response from the highest calibration standard used, repeat the test specimen dilution described in 11.1 using a higher dilution factor. Repeat the analysis procedure described in 9.2 through 9.3 on this new test specimen solution. 11.4 Inspect the boat and combustion tube to verily complete combustion of the test specimen solution. Increase
I Nitrogen, (p.g/g) = ~ VxKv
(4)
where: D = density of test specimen solution, g/mL, I = average of visual display readings of test specimen solution, ng nitrogen, Kg = gravimetric dilution factor, mass of test specimen/ mass of test specimen and solvent, g/g, K,. = volumetric dilution factor, mass of test specimen/ volume of test specimen and solvent, g/mL, M = mass of test specimen solution injected, either measured directly or calculated from measured volume injected and density, V x D, mg, and V = volume of test specimen solution injected, either measured directly or calculated from measured mass injected and density, M/D, laL.
959
I~) D 5762 and independent results obtained by different operators working in different laboratories on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following values in only 1 case in 20, where X = the average of the two test results.
13. Precision and Bias 4 13.1 Repeatability--The difference between two test results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following values in only 1 case in 20, where X = the average of the two test results. r = 0.099x X/.tg/g 13.2
R = 0.291x X ~tg/g 13.3 Bias--An NIST SRM was analyzed by the cooperators participating in the repeatability and reproducibility determination. This test method showed no significant bias for this sample within the repeatability of this test method.
Reproducibility--The difference between two single
14. Keywords 14.1 chemiluminescence; nitrogen
4 Supporting cooperative data are available from ASTM Headquarters. Request RR:D02-1370.
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, if you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohocken, PA 19428.
960
~fll~ Designation: D 5769 - 95 Standard Test Method for Determination of Benzene, Toluene, and Total Aromatics in Finished Gasolines by Gas Chromatography/Mass Spectrometry 1 This standard is issued under the fixed designation D 5769; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
E 355 Practice for Gas Chromatography Terms and Relationships4
1. Scope 1.1 This test method covers the determination of benzene, toluene, and total aromatics in finished motor gasoline, including reformulated gasoline (RFG) containing oxygenated blending components, by gas chromatography/mass spectrometry (GC/MS). 1.2 This test method is applicable to the following concentration ranges, in liquid volume %, for the following aromatics: benzene, 0.1 to 3 %; toluene, l to 15 %; and total (C6-C12) aromatics, l0 to 40 %. The test method has not been tested by ASTM for gasoline samples containing a concentration of uncalibrated C10-C12 aromatic compounds greater than approximately 3 volume %. Also, the test method has not been tested by ASTM for individual hydrocarbon process streams in a refinery, such as reformates, fluid catalytic cracked naphthas, etc., used in blending of gasolines. 1.3 Results are reported to the nearest 0.01% for benzene and 0.1% for the other aromatics by either mass or liquid volume. 1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
3. Terminology 3.1 Descriptions of Terms Specific to This Standard." 3. I. 1 aromatic--in this test method, refers to any organic compound containing a benzene or naphthalene ring. 3.1.2 calibrated aromatic componentmin this test method, refers to the individual aromatic components which have a specific calibration. 3.1.3 cool on-column injectormin gas chromatography, a direct sample introduction system which is set at a temperature at or below the boiling point of solutes or solvent on injection and then heated at a rate equal to or greater than the column. Normally used to eliminate boiling point discrimination on injection or to reduce adsorption on glass liners within injectors, or both. The sample is injected directly into the head of the capillary column tubing. 3.1.4 open split interfaceDGC/MS interface used to maintain atmospheric pressure at capillary column outlet and eliminates mass spectrometer vacuum effects on the capillary column. Can be used to dilute the sample entering the mass spectrometer to maintain response linearity. 3.1.5 reconstructed ion chromatogram (RICJma limited mass chromatogram representing the intensities of ion mass spectrometric currents for only those ions having particular mass to charge ratios. Used in this test method to selectively extract or identify aromatic components in the presence of a complex hydrocarbon matrix, such as gasoline. 3.1.6 split ratio--in capillary gas chromatography, the ratio of the total flow of carrier gas to the sample inlet versus the flow of the carrier gas to the capillary column, expressed by split ratio = (S + C)/C (l) where: S = the flow rate at the splitter vent, and C = the flow rate at the column outlet. 3.1.7 total ion chromatogram (TIC)Dmass spectrometer computer output representing either the summed intensities of all scanned ion currents or a sample of the current in the ion beam for each spectrum scan plotted against the corresponding spectrum number. Generally, it can be correlated with a flame ionization detector chromatogram. 3.1.8 uncalibrated aromatic component~in this test method, refers to individual aromatics for which a calibra-
2. Referenced Documents 2.1 A S T M Standards: D 1298 Practice for Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method2 D 4052 Test Method for Density and Relative Density of Liquids by Digital Density Meter 3 D4057 Practice for Manual Sampling of Petroleum and Petroleum Product 3 D 4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards 3 J This test method is under the jurisdiction of ASTM Committee I)-2 o n Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.04 on Hydrocarbon Analysis. Current edition approved Sept. 10, 1995. Published November 1995. 2 Annual Book of ASTM Standards, Vol 05.01. Annual Book of ASTM Standards, Vol 05.02.
4 Annual Book of ASTM Standards, Vol 14.02.
961
(~ D 5769 tion is not available. These components are estimated from the calibration of several calibrated aromatic components. 3.1.9 WCOTnwall coated open tubular, a type of capillary column prepared by coating or bonding the inside wall of the capillary with a thin film of stationary phase. 4. Summary of Test Method 4.1 A gas chromatograph equipped with a methylsilicone WCOT column is interfaced to a fast scanning mass spectrometer which is suitable for capillary column GC/MS analyses. The sample is injected either through a capillary splitter port or a cool on column injector capable of introducing a small sample size without overloading the column. The capillary column is interfaced directly to the mass spectrometer or by way of an open split interface or other appropriate device. 4.2 Calibration is performed on a mass basis, using mixtures of specified pure aromatic hydrocarbons. Volume percent data is calculated from the densities of the individual components and the density of the sample. A multipoint calibration consisting of at least five levels and bracketing the expected concentrations of the specified individual aromatics is required. Specified deuterated hydrocarbons are used as the internal standards, for example, d6-benzene for quantitating benzene. Unidentified aromatic hydrocarbons present which have not been specifically calibrated for are quantitated using the calibration of an adjacent calibrated compound and summed with the other aromatic components to obtain a total aromatic concentration of the sample. 4.3 Specified quality control mixture(s) must be analyzed to monitor the performance of the calibrated GC/MS system. 5. Significance and Use 5.1 Test methods to determine benzene and the aromatic content of gasoline are necessary to assess product quality and to meet new fuel regulations. 5.2 This test method can be used for gasolines that contain oxygenates (alcohols and ethers) as additives. It has been determined that the common oxygenates found in finished gasoline do not interfere with the analysis of benzene and other aromatics by this test method. 6. Apparatus and Materials
be less than one-fifth the peak width at half height, that is, there must be at least five full scans across the peak at half height. 6.2.2 The mass spectrometer must be capable of being interfaced to a gas chromatograph and WCOT columns. The interface must be at a high enough temperature to prevent condensation of components boiling up to 220"C, usually 20°C above the final column temperature is adequate. Direct column interface to the mass spectrometer can be used. An open split interface with computer controlled programmable flow controller(s) can also be used, particularly with cool on-column injections, to maintain all aromatic components within the linearity of the mass spectrometer and at the same time maintain detectability of lower concentration aromatic components. For example, a higher open-split-interface make-up gas flow can be used for the high concentration components such as toluene and xylenes, and a lower make-up gas flow rate may be used during the elution of the lower concentration benzene and C9+ components. Other interfaces may be used provided the criteria of Sections 9 and 10 are met. 6.2.3 A computer system must be interfaced to the mass spectrometer to allow acquisition of continuous mass scans or total ion chromatogram (TIC) for the duration of the chromatographic program. Software must be available to allow searching any GC/MS run for specific ions or reconstructed ions and plotting the intensity of the ions with respect to time or scan number. The ability to integrate the area under a specific ion plot peak is essential for quantitation. The quantitation software must allow linear least squares or quadratic nonlinear regression and quantitation with multiple internal standards. It is also recommended that software be available to automatically perform the identification of aromatic components as specified in 13.1.1. 7. Reagents and Materials 7.1 Carrier GasnThe recommended minimum purity of the carrier gas used is 99.85 mole %. Additional purification using commercially available scrubbing reagents may be necessary to remove trace oxygen which may deteriorate the performance of the GC WCOT. Helium and hydrogen have been used successfully. NOTE 1: WarningmHelium and hydrogen are supplied under high pressure. Hydrogen can be explosive and requires special handling. Hydrogen monitors that automatically shut off supply to the GC in case of serious leaks are available from GC supply manufacturers.
6.1 Gas Chromatography." 6.1.1 Gas Chromatographic System, equipped with temperature programmable gas chromatograph suitable for split injections with WCOT column or cool-on-column injector which allows the injection of small (for example, 0.1 ~L) samples at the head of the WCOT column or a retention gap. An autosampler is m~ndatory for the on-column injections. 6.1.2 WCOT Column, containing 100 % methylsilicone bonded stationary phase. For on-column injections a column containing a thicker film of stationary phase, such as 4 to 5 micron, is recommended to prevent column sample overload.
7.2 Standards for Calibration and Identification--Aromatic hydrocarbons used to prepare standards should be 99 % or greater purity (Table 1). If reagents of high purity are not available, an accurate assay of the reagent must be performed using a properly calibrated GC or other techniques. The concentration of the impurities that overlap the other calibration components must be known and used to correct the concentration of the calibration components. Because of the error that may be introduced from impurity corrections, the use of only high purity reagents is strongly recommended. Standards are used for calibration as well for establishing the identification by retention time in conjunction with mass spectral match (13.1.1 ). 7.3 Internal Standards--Deuterated analogs of benzene,
6.2 Mass Spectrometry." 6.2.1 Mass Spectrometer, capable of producing electron impact spectra at 70 or higher electron volts or equivalent and capable of scanning the range of the specified quantitation masses or m/e. The scan time in seconds must 962
~
D 5769 8. Sampling 8.1 Every effort should be made to ensure that the sample is representative of the fuel source from which it is taken. Follow the recommendations of Practice D 4057 or its equivalent when obtaining samples from bulk storage or pipelines. Sampling to meet certain regulatory specifications may require the use of specific sampling procedures. Consult appropriate regulations. 8.2 Appropriate steps should be taken to minimize the loss of light hydrocarbons from the gasoline sample while sampling and during analyses. Upon receipt in the laboratory, chill the sample in its original container to 0 to 5"C (32 to 40*F) before and after a sample aliquot is removed for analysis. 8.3 After the sample is prepared for analysis with internal standard(s), chill the sample and transfer to an appropriate autosampler vial with minimal headspace. The remainder of the sample should be re-chilled immediately and protected from evaporation for further analyses, if necessary. The autosampler vials should be chilled until ready for analyses.
TABLE 1 GC/MS Calibration Components (Calibrated Aromatic Components) Compound
CAS Number
Benzene Methylbenzene Ethylbenzene
71-43-2 108-88-3 100-41-4
1,3-Dimethylbenzene
108-38-3
1,4-D=methylbenzene 1,2-Dimethylbenzene (1-Methylethyl)-benzene Propyl-benzene 1-Methyl-3-ethylbenzene 1-Methyl-4-ethylbenzene t ,3,5-Trimethylbenzene 1-Methyl-2-ethylbenzene 1,2,4-Trimethylbenzene 1,2,3-Tdmethylbenzene Indan 1,4-Diethylbenzene Butylbenzene 1,2-Diethylbenzene 1,2,4,5-Tetramethylbenzene 1,2,3,5-Tetramethylbenzene Pentamethytbenzene Naphthalene 2-Methyl-Naphthalene 1-Methyl-Naphthalene
106-42-3 95-47-6 98-82-8 103-65-1 620-14-4 622-96-8 108-67-8 611-14-3 95-63-6 526-73-8 496-11-7 105-05-5 104-51-8 135-01-3 95-93-2 527-53-7 700-12-9 91-20-3 91-57-6 90-12-0
ethylbenzene and naphthalene as specified in Table 2 must be used as internal standards because of their similar chromatographic characteristics as the components analyzed. 7.4 Dilution Solvents--2,2,4-trimethylpentane (isooctane), n-heptane, n-nonane, cyclohexane or methylbenzene (toluene), or both, used as a solvent in the preparation of the calibration mixtures. Reagent grade. Free from detectable aromatics which may interfere with the analysis. NOTE 2: Warning--The gasoline samples and solvents used as reagents such as /so-octane, cyclohexane, n-heptane, n-octane and toluene are flammable and may be harmful or fatal if ingested or inhaled. Benzene is a known carcinogen. Use with proper ventilation. Safety glasses and gloves are required while preparing samples and standards. Samples should be kept in laboratory areas with single pass air handling and an automatic fire suppression system.
TABLE 2 Compound Benzene Methylbenzene Ethylbenzene 1,3-Dimethylbenzene 1,4-Dimethylbanzene 1,2-Dimethylbenzene (1-Methylethyl)-benzane Prowl-benzene 1-Methyl-3-ethylbenzene 1-Methyl-4-ethylbenzene 1,3,5-Trimethylbenzene
1-Methyl-2-ethylbenzene 1,2,4-Trimethylbenzene 1,2,3-Trimethylbenzene Indan 1,4-Diethylbenzene Butylbenzene 1,2-Diethylbenzene 1,2,4,5-Tetramethylbenzene 1,2,3,5-Tetramethylbenzane Pentamethylbenzene Naphthalene 2-Methyl-Naphthalene 1-Methyl-Naphthalene
9. Calibration 9.1 Preparation of Calibration Standards--Multi-component calibration standards using all the compounds listed in Table 1 are prepared by mass according to Practice D 4307. The standards may be prepared by combining the specified individual aromatics either into a single mixture or into multiple sets. Multiple sets may be prepared as follows: (1) Set I consists of benzene, methylbenzene (toluene), ethylbenzene, 1,2-dimethylbenzene, 1,3-dimethylbenzene and 1,4-dimethylbenzene using 2,2,4-trimethylpentane (isooctane) as a recommended dilution solvent; (2) Set II consists of the remaining C9+ components using a 50:50 mixture of 2,3,3-trimethylpentane and methylbenzene (toluene) as the recommended dilution solvent. Other solvents, such as n-nonane, or co-solvents may be used to improve solubility, chromatographic or mass spectrometric performance, provided these solvents contain no detectable
Mass Spec Quantitation Ions for Sample Components and Internal Standards Primary Ion (Dalton)
Intemal Standard (ISTD)
78 91 106 106 106 106 120 120 120 120 120 120 120 120 117 134 134 134 134 134 148 128 142 142
Benzene-d6 Ethylbenzene-dl 0 or Methylbenzene-d8 Ethylbenzene-dl 0 Ethylbenzene-dl 0 Ethylbenzene-dl 0 Ethylbenzene-dl 0 Ethylbenzene-dl 0 Ethylbenzene-dl0 Ethylbenzene-dl0 Ethylbenzene-dl0 Ethylbenzene-dl 0 Ethylbenzene-dl0 Ethylbenzene-dl0 Ethylbenzene-dl0 Ethylbenzene-dl 0 Naphthalene-el8 Naphthalene-d8 Naphthalene-d8 Naphthalene-d8 Naphthalene-d8 Naphthalene-d8 Naphthalene-d8 Naphthalene-d8 Naphthalene--d8
963
ISTD Ion (Dalton) 84 116 or 100 116 116 116 116 116 116 116 116 116 116 116 116 116 136 136 136 136 136 136 136 136 136
(@) D 5769 amounts of aromatics that will interfere with the analyses. NOTE 3 m l t may be more convenient to prepare gravimetrically pure (solvent free) batches of Set I and Set 11 components which then can be weighed into appropriate diluted standards.
9.1.1 The internal standards for Set I are benzene-d6 and ethylbenzene-dl0. Methylbenzene-d8 may be used for the quantitation of toluene. The internal standards for Set II are ethylbenzene-d 10 and naphthalene-d8. NOTE 4--Appropriate internal standards batches may be prepared and then added to calibration standards and samples in a single step.
9.1.2 A minimum of five calibration solutions must be prepared by mass for single mixtures containing all of the specified calibration compounds. If the calibration solutions are prepared in sets, then for each set five separate solutions must be prepared over the desired concentration range, for example: five calibration solutions for Set I, and five calibration solutions for Oci ~~, L. . I I . T.t.,~ -:I V. .~.I. . L '-~ I I~LULK; 3 ~ IllE; II:;q~UIII" mended volumes to be weighed into 100-mL volumetric flasks or 100-mL septum capped vials for the most concentrated calibration standard. Adjust these concentrations, as necessary, to ensure that the concentrations of the components in the actual samples are bracketed by the calibration concentrations. Solid components are weighed directly into the flask or vial. Other more dilute standards are prepared separately by weighing appropriate amounts of the pure aromatic components. 9.1.2.1 Prepare a calibration standard according to Practice D 4307 as follows: 9.1.3 Cap and record the tare weight of the 100-mL volumetric flask or vial to 0. l rag. 9.1.4 Remove the cap and carefully add an aromatic TABLE 3
Compound
Benzene Methylbenzene Ethylbenzene 1,3-Dimethylbenzene 1A-Dimethylbenzene 1,2-Dimethylbenzene (1-Methylethyl)-benzene Propyl-benzene 1-Methyl-3-ethylbenzene 1-Methyl-4-ethylbenzene 1,3,5-Trimethylbenzene 1-Methyl-2-ethylbenzene 1,2,4-Trimethylpenzene 1,2,3-Trimethylbenzene Indan 1,4-Diethylbenzene Butylbenzene 1,2-Diethylbenzene 1,2,4,5-Tetramethylbenzene 1,2,3,5-Tetramethylbenzene Pentamethylbenzene Naphthalene 2-Methyl-Naphthalene 1-Methyl-Naphthalene Uncahbrated indans Uncalibrated C10-benzenes Uncalibrated C11 benzenes Uncalibrated C12-benzenes
Relative Densities and Calibration Concentrations
Relative Density 60°F/60OF
0.8845 0 8719 0.8718 0.8688 0 8657 0.8846 0.8664 0.8665 0.8691 0.8657 0.8696 0.8851 0.8803 0.8987 0.9689 0.8664 0.8646 0 8843 0.8915 0.8946 0.9204 1.000 1.000 1.0245 1.000 0.878 1.000 1.000
component to the flask or vial starting with the least volatile component. Cap the flask and record the net mass (Wi) of the aromatic component added to 0.1 mg. 9.1.5 Repeat the addition and weighing procedure for each aromatic component. 9.1.6 If Sets I and II components were pre-mixed by weight, then to each calibration solution volumetric flask or vial, weigh appropriate volumes to yield the ten calibration solutions. Calculate the actual weight of each component by multiplying the total mass added of the combined mixture by the mass fraction of the individual components in the pre-mixed undiluted mixture. 9.1.7 Similarly add each internal standard and record its net mass (Ws) to 0.1 mg. If standards are prepared in multiple sets, then for Set I weigh 2 mL each of benzene-d6 and ethyibenzene-dl0. For Set II weigh 2 mL of ethylbenzene-dl0 and l g naphthalene-d8. 9. !.8 Dilute to !00-mL total vo!,ame the standard with the recommended solvents above, or equivalent. It is not necessary to weigh the amount of solvent added since the calculations are based on the absolute masses of the aromatic and internal standard components. 9.1.9 Similarly prepare four additional standards to cover the concentration range of interest. For example, for benzene, prepare 0.1, 0.5, 1.0, 1.5, 3.0 weight % standards; for toluene, prepare 1.0, 3.0, 5.0, 10.0, 15.0 mass % equivalent standards. 9.1.10 Store the capped calibration standards in a refrigerator at 0 to 5°C (32 to 40*F) when not in use. 9.1.11 Thoroughly mix the prepared standards using a vortex mixer or equivalent and transfer approximately 2 mL of the solution to a vial compatible with the autosampler, if
Concentrst=on S for Most Concentrated Calibration Solutions (Volume % or mL/100 mL) 3 15 5 6 6 6 3 3 3 3 3 3 5 3 3 3 3 3 3 2 2"* 2"* 2A 2 ... .
Calibration Components Prepared Into a Single Mixture Set 1 Set 1 Set 1 Set 1 Set 1 Set 1 Set 1 Set 1 Set 1 Set 1 Set 1 Set 1 Set 1 Set 1 Set 1 Sat 1 Set 1 Set 1 Set 1 Set 1 Set 1 Set 1 Set 1 Set 1
.
.
. .
.
.
"* These components are solids at ambient temperature. The values represent grams/100 mL.
964
. .
.
.
. .
.
Mixtures Set 1 Set 1 Sat 1 Set 1 Set 1 Set 1 Set 2 Set 2 Set 2 Set 2 Sat 2 Set 2 Set 2 Set 2 Set 2 Set 2 Set 2 Set 2 Sat 2 Set 2 Set 2 Set 2 Set 2 Set 2
. .
Calibration Components Prepared Into Two Sets of
.
.
@ D 5769 such equipment is used (see 5.1.1 ). Chill the vials until ready for loading on the autosampler.
TABLE 4
Conditions 1 Gas Chromatography (GC): Column
Nol L 5 - - F h g h l y precise robotic or s e m i - a u t o m a t e d sample preparanon systems are available commercially. These systems m a y be used to prepare calibration standards and samples for analyses provided that the results for the quality control reference material (Section 10) are met when prepared using the a u t o m a t e d systems.
2(l 2 - ll)
1.699(3,= + y.) where: I~ = retention time of 1,3,5-trimethylbenzene, t2 = retention time of l-methyl-2-ethylbenzene, Y2 = peak width at half height of 1,3,5-trimethylbenzene, and y= = peak width at half height l-methyl-2-ethyl benzene. 9.2.4 Prepare a solution of 0.01 mass % of 1,4-diethylbenzene and verify that it is detected with a signal:noise ratio of greater than 3. 9.2.5 Inject a solution of 3 mass % of 1,2,3-trimethylbenzene and confirm that the mass spectrometer provides a fragmentation pattern as specified in Table 5. 9.2.6 Sequentially analyze the calibration standards. 9.3 Calibration Calculations: 9.3.1 After the analyses of the calibration standards are complete, integrate the peak area of each calibration component and internal standards using the reconstructed ion chromatogram (RIC) of the characteristic calibration ion listed in Table 2. Obtain the area under the extracted ion at the retention time of the expected aromatic component (or internal standard). 9.3.2 Plot the response ratio rsp,: rsp, = (A,/A~)
60 m x 0.32 mm i.d., df = 5.0 lam methylsilicone cool on-column 0.1 track oven
temperature 50*C (0 min), 2=C/min to 190=C (0 min); 30*C/min to 300*C (1 min). Hydrogen 42 at 3000C
Oven temperature
50°C (1 min), 2*C/mm to 190 (0 mm)
Carrier gas Carrier gas linear velocity (cm/s) GC/MS Interface: GC/MS interface type
Helium 35 at 50"C
Interface temperature (C) Mass Spectrometry (MS): MS type MS data acquisition mode Scan rate (s/scan) Source temperature (C) Ionization voltage (eV) Mass scan range
280
open-split with variable flow 280
quadrupole full scan >1 approximately 250 70 45-300
quadrupole full s c a n >1 approximately 250 70 45-300
direct
A The above are approximate conditions. Fine tuning may be required to meet the criteria (detectability, resolution, etc.) specified in the test method. The items in italics are fixed operating conditions and must be used as indicated.
calibration. The value ta should be at least 0.99 or better and is calculated as follows: (~xy)= ta =
(4)
where: x = X, - ~
(5)
y = Y, - .P
(6)
and where: X i = amti ratio data point,
= average values for all (amt3 data points, Yi = corresponding rsp~ ratio data point, and = average values for all amt~ data points. Using the example ideal data set shown in Table 6, ra would be calculated as follows:
(2)
r2
where: A, = area of aromatic compound i, and A, = area of internal standard. as the y-axis versus the amount ratio amt,: amt, = IV,~ W~
Conditions 2
60mx0.25or 0.32 mm i.d., Of = 1.0 lam methylsi/icone Splitter 100:1 to 150:1 0.1-0.5 250"C
Inlector type Inlector split ratio Injection s=ze (laL) Inlector temperature (C)
9.2 G C / M S Calibration Procedure." 9.2.1 Prepare the GC/MS system according to manufacturer's instructions and set analysis operating conditions. Table 4 gives suggested operating conditions for split and on-column injection modes. 9.2.2 Before initiating the calibration procedure, tune the mass spectrometer according to manufacturer's instructions. Set the mass spectrometer data system to acquire data in the full scan (TIC-RIC) mode. 9.2.3 The WCOT must meet the resolution requirements described in 9.2.3.1 when installed in the GC/MS system. 9.2.3.1 Resolution R between 1,3,5-trimethylbenzene and 1-methyl-2-ethylbenzene at the 3 mass % level each must be equal to or greater than 4.0. R
G C / M S C o n d i t i o n s '~
.
(Zxy)~ . . (Zx2)(l~ya)
(5)(5) . (t0.0)(2.5)
1.0
(7)
9.3.4 Linear Least Squares F i t - - F o r each aromatic i calibration data set, obtain the linear least squares fit equation in the form: (rspi) = (m,)(amti) + b i,
(3)
(8)
= response ratio for aromatic I (y-axis), rni -- slope of linear equation for aromatic I, amt, = amount ratio for aromatic 1 (x-axis), and bi = y-axis intercept. The values m,. and b, are calculated as follows: rsp~
where: 147,= mass of aromatic compound i in the calibration standard, and W~ = mass of internal standard in the calibration standard. The x-axis to generate calibration curves for each aromatic component is specified in Table 1. See Fig. I for an example plot. 9.3.3 Check the correlation ta value for each aromatic
Zxy
m~ = Z---~ and 965
(9)
it~'~ D 5769 TABLE 5
TABLE 7
Mass Spectrometer Spectral Requirement For 3 mass % 1,2,3-trimethylbenzene Ion (m/e)
Relative Intensity
120 105
30-60 100
0
i
"
"
A '
' ' '
I
'
12.00
'
'
'
l
'
' ' '
I ' ' '
14,00 16,00
'
i
' ' '
'
I
' ' '
'
I
'
18,00 20,00 22,00
'
' '
I
'
' '
'
J
'
A '
' '
I
'
24,00 26,00 28,00
'
'
'
MINUTES FIG. 2a
Reconstructed Ion Chromatograms (RIC) for m/e 78 (Benzene), 91 (Methylbenzene) and 106 (C-8 Aromatics)
968
(@) D 5769 Abundance
ION 120 250000" 1-METHYL-3-ETHYLBENZENE 2 0 0 00 0 •
z
I-METHYL-4.ETHYLBENZE N E
L
,.
150000.
50000.
~ "~
-~ z uJ m ..J >'r ~-
uJ z w N Z ,,,
,
UJ
U.I
I~
--
.J
-
>-
w Z N
LIJ z
-J
W,
"
32.00
34.00
~
uJ z tu N z
~
- -
= ~
M v-"
J "
AIgl // 36.0~
L. 3--8:00
ll
.
4__0_.00
A 42.00
44.00
%bundan~e
70000
ION
[
134
l
1,4-DIETHYLBENZENE BUTYLBENZENE
uJ
60000
~ Zm
z
~/)
N
.J
>-
50000
r~
~>"
~~"
IxI "J >.
40000
~
~
~
~
-"
,'4
".
30000
~
~
I [ .0
~
m
G~
zoooo. 0 ~" ' / ~
'
r i m e - - ~ o . O0 ' ' 4 ' 2 .~0 0
' ' 4'4.00
~
' ' 4'6.00
"~
' ' 4'8.00
"~
' ' 5'0.00
.,,
' /X~ ' 5'2.00
't"
~,
' ' 5'4.00
MINUTES FIG. 2b
Reconstructed
Ion C h r o m a t o g r a m s
(RIC) for m / e (C-9 A r o m a t i c s ) a n d 134 ( C - 1 0 A r o m a t i c s )
calibration curve of pentamethylbenzene for quantitation of all detected components with mass 148. 13.1.3.8 Mass 1 6 2 - - U s e to quantitate C 12 benzenes. The concentrations of these components may be at or below detection limits. If detected, use calibration curve of pentamethyl benzene for quantitation. 13.1.3.9 Mass 1 2 8 - - U s e to quantitate naphthalene from its calibration curve. Ignore all other mass 128 peaks. 13.1.3.10 Mass 1 4 2 - - U s e to quantitate the two methylnaphthalene isomers from their corresponding calibration curves. Ignore all other mass 142 peaks.
13.1.4.1 If the calibration curves were obtained by forcing the intercept to be zero then b; = 0. 13.1.4.2 For components that yielded nonlinear calibrations as specified in 9.3.6 calculate IV, using appropriate software provided with the GC/MS system. 13.1.5 For the uncalibrated component, either sum all of their peak areas and treat the total area as a single component for quantitation or treat each uncalibrated component as a single component for quantitation and then sum their total concentrations.
NOTE 8--For the quantitation of the uncalibrated components, DO NOT include the peak areas of any calibrated components having a similar reconstructed (RIC) ion response with the summed areas of the uncalibrated components. The calibrated components are quantitated separately using their respective calibrations.
NOTE 9--It may be more appropriate to force the calibration curves used to quantitate the uncalibrated components through the zero intercept, that is, b, = 0, to prevent calculating negative results for the uncalibrated components that are present in the samples at very low concentrations.
13.1.4 From the linear least squares fit calibrations, Eq 15, calculate the absolute mass of each aromatic (IV,) in grams in the gasoline samples using the response ratio (rsp,) of the areas for the sample of the aromatic component to that of the internal standard as follows:
13.1.6 To obtain mass percent'(wi) results for each aromatic hydrocarbon, including uncalibrated aromatics: wI = ( W~/Wg)(IO0 %)
969
(16)
II~
D 5769
~bundanc~ 140000
ION 117
120000
INDAN
IOO000 80000 60000
UNCALIBRATED
INDANS
40000
20000 0 ' rime--~o.oo
'
'
'
I
'
'
'
45. O0
I
'
'
'
'
50. O0
'
)
'
'
55. O0
'
I
'
i
i
'%
"1"
J
i
~'
i
65.00
60. O0
~fiundance 60000
ION 148 uJ Z w
40000 UNCALIBRATED
.i m ..I
C11-BENZENES(ALL)
20000
o
.. . ... . ... . ... . ...
rime--::60.00
52.00
A 54.00
56.00
. -. ' r. . .'^'. .,' ..' . , 58.00
60.00
.~.,,..,.A..~:_r..,.,...,, 62.00
64.00
66.00
, . .'
68.00
MINUTES FIG. 2c
Reconstructed Ion Chromatograms (RIC) for role 117 (Indans) and 148 (C-11 Aromatics)
where: Wx= mass of gasoline sample. 13.1.7 To obtain the mass % of the total aromatic concentration w,, sum the mass % of each aromatic component, including the mass % of the uncalibrated components: w, = Zw,
(17)
13.1.8 Report results to nearest 0.01 mass %. 13.2 Volumetric Concentration of Aromatics: 13.2.1 If the volumetric concentration of each aromatic component is desired, calculate the volumetric concentration according to Eq 18:
v, = w,{O//D,)
(18)
13.2.3 Report results to nearest 0.01 volume %. 14. Precision and Bias s 14.1 Precision--The precision of this test method as determined by a statistical examination of interlaboratory results are as follows: 14.1.1 Repeatability--The difference between successive results obtained by the same operator with the same apparatus under constant operating conditions on identical test materials would, in the long run, in the normal and correct operation of the test method exceed the following values only in one case in twenty: Volume benzene toluene total aromatics
0.059(20 O.061(X + 1.3) 0.027(X + 4.4)
Mass 0.052(20 0.088(20 0.025(X + 7,3)
where: v, = volume % of each aromatic to be determined, D, = relative density at 60*F (15.56"C) of the individual aromatics as found in Table 2, and Dy = relative density of the fuel under study as determined by Test Methods D 1298 or D 4052. 13.2.2 To obtain the volume percent of the total aromatic concentration Vt, sum the volume % of each aromatic component, including the volume percent of the uncalibrated components:
where X is the mean mass or volume % of the component. 14.1.2 Reproducibility--The difference between two single and independent results obtained by different operators working in different laboratories on identical test materials would, in the long run, in the normal and correct operation of the test method exceed the following values only in one case in twenty:
(19)
For the volume % precision for total aromatics and benzene, constant density values tbr the round-robin samples were provided to the round-robin participants.
VI = ~ V !
970
~
D 5769
~,bundance
50000
ION 128
40 0 0 0
NAPHTHALENE
30000
20000
i0000 i
o
~ime-->50.O0 Abundance
~.~,'-., 52.00
-~.~-
54.00
56,00
,,,~--~' 58.00
60.00
.... ~,
62.00
~',
64.00
66.00
68.00
ION 142
50000
40000 2-METHYL-NAPHTHALENE 30000
20000 1-METHYL-NAPHTHALENE
A
lO000
,
Pime--~O.O0
52.00
54.00
56.00
i
58.00
J
60.00
.t
62.00
,
i
,~JL~',',,', ,', ',,~
64.00
66.00
68.00
MINUTES FIG. 2d
benzene toluene total aromatics
Reconstructed Ion Chromatograms (RIC) for m/e 128 (Naphthalene) and 142 (MethyI-Napthalenes) Volume
Mass
0.11(X) 0.14(X + 1,3) 0.10(X + 4.4)
0.11(X) 0.17(X) 0.091(X + 7.3)
suitable for determining the bias for the procedures in this test method bias cannot be determined.
15. Keywords
where X is the mean mass or volume % of the component. 14.2 Bias--Since there is no certified reference material
15.1 aromatics; benzene; GC/MS; gasolines; gas chromatography; mass spectrometry; toluene
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and ff not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohocken, PA 19428.
971
(~l~
Designation: D 577e - 95 Standard Test Method for Bromine Index of Aromatic Hydrocarbons by Electrometric Titration 1 This standard is issued under the fixed designation D 5776; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
3.1.1 bromine index--the number of milligrams of bromine consumed by 100 g of sample under given conditions.
1. Scope 1.1 This test method determines the amount of brominereactive material in aromatic hydrocarbons and is thus a measure of trace amounts of unsaturates in these materials. It is applicable to materials having bromine indexes below 500. 1.2 This test method is applicable to aromatic hydrocarbons containing no more than trace amounts of olefins and that are substantially free from material lighter than isobutane and have a distillation end point under 288"C (550"F). 1.3 The following applies to all specified limits in this standard: For purposes of determining conformance with this standard, an observed value shall be rounded off "to the nearest unit" in the last right hand digit used in expressing the specification limit, in accordance with the rounding off method of Practice E 29. 1.4 This standard does not purport to address all of the safi,ly concerns, if any, associated with its use. It is the re37)onsibility of the user of this standard to establish appropriate saJety and health practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement see Section 8.
4. Summary of Test Method 4.1 The specimen dissolved in a specified solvent is titrated with standard bromide-bromate solution. The end point is indicated by a fixed end-point electrometric titration apparatus, when the presence of free bromine causes a sudden change in the polarization voltage of the system. 5. Significance and Use 5.1 This test method is suitable for setting specification, for use as an internal quality control tool, and for use in development or research work on industrial aromatic hydrocarbons and related material. This test method gives a broad indication of olefinic content. It does not differentiate between the types of aliphatic unsaturation. 6. Apparatus 6.1 Fixed End Point Electrometric Titration Apparatus-Any fixed end-point apparatus may be used incorporating a high resistance polarizing current supply capable of maintaining approximately 10 to 50 ~tA across two platinum plate electrodes or a combination platinum electrode and with a sensitivity such that a voltage change of approximately 50 mV at these electrodes is sufficient to indicate the end point (see Note 1).
2. Referenced Documents
2.1 ASTM Standards." D 1193 Specification for Reagent Water 2 D 1159 Test Method for Bromine Number of Petroleum Distillates and Commercial Aliphatic Olefins by Electrometric Titration 3 D 3437 Practice for Sampling and Handling Liquid Cyclic Products 4 E 29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications5 2.2 Other Document: OSHA Regulations, 29 CFR paragraphs 1910.1000 and 1910.12006
NOTE l--The reagents and techniques may be checked by determining the bromine index of a 100 mg/kg cyclohexenein heptane. This is expected to give a bromine index of 180 to 200 mg/100 g sample. Refer to Table A2.1 of Test Method D 1159. 6.2 Titration Vessel--A tall form glass beaker of approximately 250-mL capacity or a water jacketed titration vessel of approximately 250-mL capacity connected to a refrigerated circulating water bath controlling the temperature at 0 to 5"C. A pair of platinum electrodes spaced not more than 5 mm apart, shall be mounted to extend well below the liquid level. Stirring shall be by a mechanical or electromagnetic stirrer and shall be rapid but not so vigorous as to draw air bubbles down to the electrodes. 6.3 Iodine Number Flasks, glass-stoppered, 500-mL capacity.
3. Terminology 3.1 Definition: This test method is under the jurisdiction of ASTM Committee D-16 on Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of Subcommittee D I6.0E on Instrumental Analysis. Current edition approved Sept. 15, 1995. Published November 1995. 2 Annual Book of ASTM Standards, Vol I 1.01. 3 Annual Book of ASTM Standards, Vol 05.01. 4 Annual Book of ASTM Standards, Vol 06.04. 5 Annual Book of ASTM Standards, Vol 14.02. 6 Available from Superintendent of Documents U.S. Government Printing Office, Washington, DC 20402.
7. Reagents and Materials 7.1 Purity of Reagents--Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the American Chemical Society where such specifications are 972
~@) D 5776 TABLE 1
available. 7 Other grades may be used, providing it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 7.2 Purity of Water--Unless otherwise indicated references to water shall be understood to mean reagent water conforming to Type III of Specification D 1193. 7.3 Bromide-Bromate Standard Solution (0.10 N)S--Dissolve 10.1 g of potassium bromide (KBr) and 2.8 g potassium bromate (KBrO3) in water and dilute to 1.0 L. Standardize to four significant figures as follows: Place 50 mL of glacial acetic acid and 1.0 mL of concentrated hydrochloric acid (HCI, sp gr 1.19) in a 500-mL iodine number flask. Chill the solution in an ice bath for approximately 10 min and with constant swirling of the flask, add from a 50-mL buret 40 to 45 mL of bromide bromate solution, estimated to the nearest 0.01 mL, at a rate such that the addition takes between 90 and 120 s. Stopper the flask immediately, shake the contents, place it again in the ice bath, and add 5.0 mL of potassium iodide (KI) solution in the lip of the flask. After 5 min remove the flask from the ice bath and allow the KI solution to flow into the flask by slowly removing the stopper. Shake vigorously, add 100 mL of water in such a manner as to rinse the stopper, lip, and walls of flask, and titrate promptly with the standard sodium thiosulphate (Na2S203) solution. Near the end of the titration add 1 mL of starch indicator solution and titrate slowly to the disappearance of the blue color. 7.4 Electronic Standardization of Bromide-Bromate Solulion--Standardize to four significant figures as follows: Place 50 mL of glacial acetic acid and 1.0 mL of concentrated hydrochloric acid (HCI, sp gr 1.19) in a 500-mL iodine number flask. Chill the solution in an ice bath for approximately 10 rain with constant swirling of the flask, add 4.00 mL of bromide bromate solution from the auto buret. Stopper the flask immediately and, shake the contents, then cool it in a ice bath for 5 min. Add 4.0 mL of potassium iodide (KI) to the lip of the flask, remove the flask from the ice bath and allow the KI solution to slowly flow into the flask by removing the stopper. Shake vigorously, transfer to a chilled beaker and rinse the flask including stopper with 100 mL of water. Immerse the electrodes into the solution, titrate with standard sodium thiosulphate (Na2S203) to an end point indicated by a significant change in potential that persists for 30 s (see Note 3).
Bromine Index 0 to 20 20 to 100 100 to 200 200 to 500
Sample Size Sample Size, g 50 30 to 40 20 to 30 8 to 10
7.6 Sodium Thiosulphate, Standard Solution (0.10 N)-Dissolve 25.0 g of sodium thiosulphate pentahydrate (Na2S203.5H20) in water and add 0.02 g of sodium carbonate (Na2CO3) to stabilize the solution. Dilute to 1.0 L and mix thoroughly by shaking. Standardize by any accepted procedure that determines the normality with an error not greater than +0.0002. Restandardize at intervals frequent enough to detect changes of 0.0005 in normality. 7.7 Starch Solution9--Mill 5 g of arrow-root starch with 3 to 5 mL of water. Add the suspension to 2 L of boiling water. As a preservative, 5 to 10 mg of mercuric iodide (HgI2) or 0.2 g of salicylic acid can also be added. Boil for 5 to 10 min, then allow to cool and decant the clear supernatant liquid into glass stoppered bottles. 7.8 Sulphuric Acid (1 + 5)mCarefully add 1 volume of concentrated sulphuric acid (H2SO4 sp gr 1.84) to 5 volumes of water and thoroughly mix. 7.9 Acetic Acid, glacial. 7.10 1-Methyl-2-Pyrrolidinone. 7.11 Titration Solvent--Prepare 1 L of titration solvent by mixing the following volumes of materials: 714 mL of glacial acetic acid, 134 mL of l-Methyl-2-Pyrrolidinone, 134 mL of methanol and 18 mL of H2SO 4 (1 + 5). 8. Hazards 8.1 Consult current OSHA regulations, suppliers' Material Safety Data Sheets, and local regulations for all materials used in this test method. 9. Sampling 9.1 Sample the material in accordance with Practice D 3437. 10. Procedure 10.1 Switch on the titrator and allow the electrical circuits to stabilize according to the manufacturer's instructions. 10.2 Introduce 150 mL of titration solvent into the titration vessel and pipet or weigh in a quantity of sample as indicated in Table l (Note 4). The sample must be completely dissolved in the titration solvent. Switch on the stirrer and adjust to a rapid stirring rate, but avoid any tendency for air bubbles to be drawn down into the solution.
NOTE 3--With commercial titrators, a sudden change in potential is indicated on the meter or dial of the instrument as the endpoint is approached. When this change persists for 30 s it marks the end of the titration. With each instrument, the manufacturer's instructions should be followedto achieve the sensitivityachieved in the platinum electrode circuit.
NOTE 4 - - F r e q u e n t l y the order o f m a g n i t u d e o f the b r o m i n e index of
a sample is unknown. In this case, a trial test is recommended using an 8 to 10-g sample in order to obtain the approximate magnitude of the bromine index. This exploratory test should be followed with another determination using the appropriate sample size as indicated in Table I. The sample mass may be determined by obtaining the density of the sample and calculating the mass of a measured volume.
7.5 Potassium Iodide Solution (150 g/L}--Dissolve 150 g of potassium iodide (KI) in water and dilute to 1.0 L. 7 Reagent Chemicals, American Chemtcal Socwty Specificattons, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD. a The 0.10 N bromide-bromate standard solution is available corhmercially from laboratory chemical suppliers.
10.3 Start the titration with the bromide-bromate solution according to the optimized instrument conditions. Continue 9 Arrow-root starch indicator solution may also be purchased prepared from chemical suppliers.
973
(@) D 5776 7990 = molecular weight of bromine x 100.
the titration until a significant change in potential persisting for 30 s marks the endpoint of the titration. 10.4 Blanks--Make duplicate blank titrations on each batch of titration solvent and reagents. Make sure that less than O. 10 mL of bromide-bromate solution is required.
12. Report 12.1 Report the following information: 12.l.1 Bromine index to the nearest 0.5 mg/100 g.
11. Calculations 11.1 Calculate the normality of the bromide-bromate solution as follow: N I = A2N2/A
I
13. Precision and Bias 13.1 Precision--Based on limited information (32 analysis by one operator) from one laboratory, the absolute standard deviation of 0.24 at the 2.8 mg/100 g bromine index level was obtained.
(1)
where: N~ = normality of the bromide-bromate solution, A, = bromide-bromate solution, mL, A2 = Na2S203 solution required for titration of the bromidebromate solution, mL, and N2 = normality of the Na2S203 solution. 11.2 Calculate the bromine index as follows: Bromine index = [(A - B)N x 7990]/W (2)
13.1.1 Intermediate Precision (formerly called Repeatability)--The 95 % repeatability limits at the 2.8 mg/100 g levels are approximately +0.7. 13.1.2 Reproducibility--The reproducibility of this test method is being determined. 13.2 Bias--Since there is no accepted reference material suitable for determining the bias of the procedure in this test method, bias has not been determined.
where: A = bromide-bromate solution required for titration of the sample, mL, B = bromide-bromate solution required for titration of the blank, mL, N = normality of bromide-bromate solution, W = sample, g, and
14. Keywords 14.1 aromatic hydrocarbons; bromine index; brominereactive; electrometric titration
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and ff not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
974
(~
Designation:D 5799 - 95 Standard Test Method for Determination of Peroxides in Butadiene I This standard is issued under the fixed designation D 5799; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (0 indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 This procedure covers the determination of peroxides in butadiene. 1.2 This test method covers the concentrations range of l to l0 ppm by mass (ppmw) as available oxygen. 1.3 This standard does not purport to address all of the
5.4 Heating Mantle, electric for 250-mL Erlenmeyer flasks. 5.5 Microburette, 10-mL capacity, graduated in 0.02-mL divisions. 5.6 Water Bath, a thermostatically controlled liquid bath capable of maintaining a water temperature of 60 + 1°C (140 + 2*FO.
safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicab:Tity of regulatory limitations prior to use.
6. Reagents 6.1 Purity of Reagents--Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available. 4 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 6.2 Purity of Water--Unless otherwise indicated, references to water shall be understood to mean deionized or distilled water. 6.3 Acetic Acid, 94 % by volume. Mix 60 mL of water with 940 mL of glacial acetic acid (CH3COOH). NOTE h Warning--Danger--Poisonous and corrosive. Combustible. Maybe fatalif swallowed.Causessevereburns. Harmfulif inhaled. 6.4 Carbon Dioxide, solid (dry ice).
2. Referenced Documents
2.1 ASTM Standards: D 1265 Practice for Sampling Liquefied Petroleum (LP) Gases-Manual Method2 D 3700 Practice for Containing Hydrocarbons Fluid Samples Using a Floating Piston Cylinder3 3. Summary of Test Method 3.1 A known mass of the butadiene sample is placed in a flask and evaporated. The residue is then refluxed with acetic acid and sodium iodide reagents. The peroxides react to liberate iodine which is titrated with standard sodium thiosulfate solution using visual end-point detection. Interfeting traces of iron are complexed with sodium fluoride.
NOTE 2: W a r n l n ~ m U s e gloves to avoid frostbite when handling.
4. Significance and Use 4.1 Due to the inherent danger of peroxides in butadiene, specification limits are usually set for their presence. This test method will provide values that can be used to determine the peroxide content of a sample of commercial butadiene. 4.2 Butadiene polyperoxide is a very dangerous product of the reaction between butadiene and oxygen that can occur. The peroxide has been reported to be the cause of some violent explosions in vessels that are used to store butadiene.
6.5 Potassium Dichromate Solution, Standard (O.I N)-Dissolve 2.452 g of potassium dichromate (K2Cr207) in water and dilute to 500 mL in a volumetric flask. NOTE 3: Warning--Avoid contact with eyes and skin and avoid breathing of dust. 6.6 Sodium Fluoride. 6.7 Sodium Iodide. 6.8 Sodium Thiosulfate Solution, Standard (0.1 N)-Dissolve 12.5 g of sodium thiosulfate (Na2S203 x 5H20 ) plus 0.1 g of sodium carbonate (Na2CO3) in 500 mL ofwater (the Na2CO3 is added to stabili7e the Na2S203 solution). Let this solution stand a week or more before using. Standardize against 0.1 N K2Cr207 solution. Restandardize at frequencies to detect changes of 0.0005 in normality.
5. Apparatus 5.1 Condensers, Liebig, with 24/40 standard-tapered ground-glass joint connections. 5.2 Cylinders, graduated, 100-mL capacity. 5.3 Flask, Erlenmeyer, 250-mL capacity, with 24/40 standard-tapered ground-glass connections with marking at 100 mL.
7. Sampling 7.1 Butadiene should be sampled in a metal container of a
a This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.D on Hydrocarbons for Chemical and Special Uses. Current edition approved Oct. 10, 1995. Published December 1995. 2 Annual Book of ASTM Standards, Vol 05.01. 3 Annual Book of ASTM Standards, Vol 05.02.
4 Reagent Chemicals. American Chemical Society SpecOTcations, American Chemical Society, Washington, DC. For sugsestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD.
975
(@) D 5799 type which ensures maximum safety and which is resistant to butadiene corrosion. The size of the container is dependent upon the number of times the test is to be performed according to this test method. Refer to Practice D 1265 or Practice D 3700 for instructions on sampling.
9. Calculation 9.1 Calculate the peroxide content as follows: ( A - B ) x N x 16000 peroxide, as 02, ppmw -W
where: A = N a 2 S 2 0 3 solution required for titration of the sample, mL, B = Na2S203 solution required for titration of the blank, mL, N = normality of the Na2S203 solution, W = sample weight, g, and 16 000 = milliequivalents of oxygen.
8. Procedure 8.1 Remove the oxygen from a 250-mL Erlenmeyer flask by adding several pellets (approximately 1 cm in size) of dry ice and allowing the CO 2 to displace the air. This will take approximately 5 min. 8.2 Record the weight to one decimal place of the sample cylinder, and then transfer approximately 100 mLs of butadiene sample from the cylinder to the 250 mL Erlenmeyer flask containing several pellets of dry ice. Reweigh the sample cylinder and record the weight of the sample as the difference of the two weights.
10. Precision and Bias s 10.1 Precision--The precision of this test method as determined by statistical examination of interlaboratory results is as follows: 10.1.1 Repeatability--The difference between two test results obtained by the same operator with the same apparatus under constant operating conditions on identical test materials would, in the long run, in the normal and correct operation of the test method, exceed the following values only in one case of twenty:
NOTE 4: Warning--Butadiene is a flammable gas under pressure. 8.3 Place the flask in a water bath at 60°C in a well ventilated hood. Allow the butadiene to evaporate while keeping an inert atmosphere above the liquid butadiene by continuing to add pellets of dry ice at intervals until all the butadiene has evaporated.
R = 1.4 ppmw
NOTE 5: Warning--Peroxides are unstable and react violently when taken to dryness. Peroxides at the levels experienced during the test method evaluation have not caused a problem, but caution needs to be exhibited in handling by the use of personal protective equipment.
10.1.2 Reproducibility--The difference between two single and independent results, obtained by different operators working in different laboratories on identical test material, would, in the long run and in the normal and correct operation of the test method, exceed the following values only in one case in twenty. R = 3.4 ppmw
8.4 Remove the flask from the water bath and allow to cool to ambient temperature. Add 50 mL of 94 % acetic acid and 0.20 + 0.02 g of sodium fluoride. Add several more pellets of dry ice to the flask and allow to stand for 5 min. 8.5 Add 6.0 + 0.2 g of sodium iodide to the flask and immediately connect to the Liebig condenser. Turn on the heating mantle and reflux the solution for 25 + 5 min. Keep the equipment away from strong light during refluxing. 8.6 At the end of the reaction period, turn off the heating mantle and remove the flask with condenser from the mantle. Immediately add 100 mL of water through the top of the condenser followed by several pellets of dry ice. 8.7 Maintaining an inert atmosphere with CO2 pellets, remove the flask from the condenser and allow to cool to ambient temperature. Cold water may be used to assist in this step. Titrate the liberated iodine with 0.1 N sodium thiosulfate until a clear endpoint is reached. 8.8 Repeat 8.4 through 8.7 for the reagent blank.
10.2 Bias--As no reliable source of butadiene polyperoxide is available, the actual bias of the test method is unknown; but published data reports that this test method determines 90 % of the polyperoxide. 6 11. Keywords 11.1 butadiene; butadiene polyperoxide; peroxide 5 Supporting data is available from ASTM Headquarters. Request RR:D02:1372. 6 For a discussion of the background for this test method, see Mayo, Hendry, Jones, and Scheatzlc, Industrialand Engineering Chemical, Product Research, Vol
7, 1968, p. 145.
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reepproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohocken, PA 19428.
976
~[~
Designation: D 5808 - 95
Standard Test Method for Determining Organic Chloride in Aromatic Hydrocarbons and Related Chemicals by Microcoulometry 1 This standard is issued under the fixed designation D 5808; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 This test method covers the organic chlorides in aromatic hydrocarbons, their derivatives, and related chemicals. 1.2 This test method is applicable to samples with chloride concentrations from 1 to 25 mg/kg. 1.3 This test method is preferred over Test Method D 5194 for products, such as styrene, that are polymerized by the sodium biphenyl reagent. 1.4 The following applies to all specified limits in this standard: for purposes of determining conformance with this standard, an observed value or a calculated value shall be rounded off "to the nearest unit" in the last right-hand digit used in expressing the specification limit, in accordance with the rounding-off method of Practice E 29. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Note 2 and Section 9.
2. Referenced Documents 2.1 A S T M Standards: D 1193 Specification for Reagent Water2 D 3437 Practice for Sampling and Handling Liquid Cyclic Products3 D 5194 Test Method for Trace Chloride in Liquid Aromatic Hydrocarbons3 E 29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications 4 2.2 Other Document: OSHA Regulations--29CFR paragraphs 1910.1000 and 1910.12005
3. Terminology 3.1 Definitions: 3.1.1 dehydration tube--a chamber containing concentrated sulfuric acid that scrubs the effluent gases from combustion to remove water vapor.
3.1.2 oxidative pyrolysis--a process in which a sample is combusted in an oxygen-rich atmosphere at high temperature to break down the components of the sample into elemental oxides. 3.1.3 recovery factor--an indication of the efficiency of the measurement computed by dividing the measured value of a standard by its theoretical value. 3.1.4 reference sensor pair--detects changes in silver ion concentration. 3.1.5 test titration--a process that allows the coulometer to set the endpoint and gain values to be used for sample analysis. 3.1.6 titration parameters--various instrumental conditions that can be changed for different types of analysis. 3.1.7 working electrode (generator electrode)--an electrode consisting of an anode and a cathode separated by a salt bridge; maintains a constant silver ion concentration.
4. Summary of Test Method 4.1 A liquid specimen is injected into a combustion tube maintained at 900"C having a flowing stream of 50 % oxygen and 50 % argon carder gas. Oxidative pyrolysis converts the organic halides to hydrogen halides that then flow into a titration cell where it reacts with silver ions present in the electrolyte. The silver ion thus consumed is coulometrically replaced and the total electrical work to replace it is a measure of the organic halides in the specimen injected (see Annex A 1).
5. Significance and Use 5.1 Organic as well as inorganic chlorine compounds can prove harmful to equipment and reactions in processes involving hydrocarbons. 5.2 Maximum chloride levels are often specified for process streams and for hydrocarbon products. 5.3 Organic chloride species are potentially damaging to refinery processes. Hydrochloric acid can be produced in hydrotreating or reforming reactors and this acid accumulates in condensing regions of the refinery.
6. Interferences 6.1 Both nitrogen and sulfur interfere at concentrations greater than approximately 0.1%.
This test method is under the jurisdiction of ASTM Committee D-16 on Aromatic Hydrocarbons and Related Chemicals is the direct responsibility of Subcommittee DI6.0E on Instrumental Analysis. Current edition approved Oct. 10, 1995. Published December 1995. 2 Annual Book of ASTM Standards, Vol 11.01. 3 Annual Book of ASTM Standards, Vol 06.04. 4 Annual Book of ASTM Standards, Vol 14.02. 5 Available from Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402.
NOT~ l--To ensure reliable detectability, all sources of chloride contamination must be eliminated. 6.2 Bromides and iodides, if present, will be calculated as chlorides. However, fluorides are not detected by this test method. 977
~
D 5808
6.3 Organic chloride values of samples containing inorganic chlorides will be biased high due to partial recovery of inorganic species during combustion. Interference from inorganic species can be reduced by water washing the sample before analysis. This does not apply to water soluble samples.
used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available. 7 Other grades may be used, provided that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 8.2 Purity of WatermUnless otherwise indicated, references to water shall be understood to mean reagent water conforming to Specification D 1193, Type II or III. 8.3 Acetic Acid (sp gr 1.05)--Glacial acetic acid (CH3COOH). 8.4 Argon or Helium, 99.9 % minimum purity required as carder gas. 8.5 Sodium Acetate, anhydrous, (NaCHaCO2), fine granular. 8.6 Cell Electrolyte Solution--Dissolve 1.35 g sodium acetate (NaCH3CO2) in 850 mL of acetic acid (CH3COOH), and dilute to 1000 mL with water.
7. Apparatus 6
7.1 Pyrolysis Furnace, which can maintain a temperature sufficient to pyrolyze the organic matrix and convert all chlorine present in the sample to hydrogen chloride. 7.2 Pyrolysis Tube, made of quartz and constructed so that when a sample is volatilized in the front of the furnace, it is swept into the pyrolysis zone by an inert gas, where it combusts when in the presence of oxygen. The inlet end of the tube must have a sample inlet port with a septum through which the sample can be injected by syringe. The inlet end must also have side arms for the introduction of oxygen and inert carder gas. The pyrolysis tube must be of ample volume, so that complete pyrolysis of the sample is ensured. 7.3 Titration Cell, containing a reference electrode, a working electrode, and a silver sensor electrode, as well as a magnetic stirrer. An inlet from the pyrolysis tube is also required.
NOTE 3 - - B u l k quantifies o f the electrolyte should be stored in a dark bottle or in a dark place and be prepared fresh at least every two weeks.
8.7 Oxygen, 99.6 % minimum purity is required as the reactant gas. 8.8 Gas Regulators, two-stage gas regulators must be used for the reactant and carder gas. 8.9 Potassium Nitrate (KN03), fine granular. 8.10 Potassium Chloride (KCI), fine granular.
NOTE 2: Caution--Excessive stirring speed will decouple the stirring bar, and cause it to rise in the titration cell and possibly damage the electrodes. A slight vortex in the cell will be adequate.
8.11 Working Electrode Solution (I0 % KNO3)--Dissolve 50 g potassium nitrate (KNO3) in 500 mL of distilled water. 8.12 Inner Chamber Reference Electrode Solution (1 M KCl)~Dissolve 7.46 g potassium chloride (KCI) in 100 mL of distilled water. 8.13 Outer Chamber Reference Electrode Solution (1 M KNO~)mDissolve 10.1 g potassium nitrate (KNO3) in 100 mL of distilled water. 8.14 Sodium Chloride (NaCl), fine granular. 8.15 Sulfuric Acid, (sp gr 1.84), (H2SO4) concentrated. 8.16 2,4,6-Trichlorophenol (TCP) (CrH30CI~), fine granular. 8.17 Methanol (MeOH) (CH3OH), 99.9 % minimum purity. 8.18 Chloride Standard Stock SolutionmWeigh accurately 0.1 g of 2,4,6-Trichlorophenol to 0. I rag. Transfer to a 500-mL volumetric flask. Dilute to the mark with methanol.
7.4 Microcouiometer, capable of measuring the potential of the sensing-reference electrode pair, and comparing this potential with a bias potential, and amplifying the difference to the working electrode pair to generate a current. The microcoulometer output voltage signal should be proportional to the generating current. 7.5 Automatic Boat Drive, having variable stops, such that the sample boat may be driven into the furnace, and stopped at various points as it enters the furnace. 7.6 Controller, with connections for the reference, working, and sensor electrodes. The controller is used for setting of operating parameters and integration of data. 7.7 Dehydration Tube, positioned at the end of the pyrolysis tube so that effluent gases are bubbled through a sulfuric acid solution, and water vapor is subsequently trapped, while all other gases are allowed to flow into the titration cell. 7.8 Gas-Tight Sampling Syringe, having a 50 ~tl capacity, capable of accurately delivering 10 to 40 ~tl of sample. 7.9 Quartz Boats.
Ci/L, mg MeOH (ppm) -- g ofTCP x 0.5386 x 103 L of MeOH where: TCP --- 2,4,6, Trichlorophenol, and MeOH = Methanol.
8. Reagents and Materials
8.1 Purity of Reagents--Reagent grade chemicals shall be 7 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the Umted States Pharmacopeia and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD.
6 Microcoulometer such as the TOX-10Z and TOX-10, manufactured by Mitsubishi Chemical Corporation, and available through Cosa Instruments, 55 Oak Street, Norwood, NJ 07648, or equivalent instrument, has been found satisfactory for this purpose.
978
o s8oa 12.4.1 Volumetric measurement can be utilized by filling the syringe with standard, carefully eliminating all bubbles, and pushing the plunger to a calibrated mark on the syringe, and recording the volume of liquid in the syringe. After injecting the standard, read the volume remaining in the syringe. The difference between the two volume readings is the volume of standard injected. This test method requires the known or measured specific gravity or density, to the third decimal place. Several densities of various hydrocarbons are listed in Table 2. A sample size of 40 lxL is suggested to start, and then this volume can be adjusted to accommodate more quickly or more accurate determinations. 12.4.2 Alternatively, the syringe may be weighed before and after the injection to determine the weight of sample injected. This technique provides greater precision than the volume delivery method, provided a balance with a precision of ± 0.0001 g is used. 12.5 Insert the syringe needle through the septum and into the quartz boat inside the boat drive. Start the boat drive, and insert the standard into the pyrolysis furnace. 12.6 Repeat the measurement of each calibration standard at least three times. 12.7 If a low recovery factor (less than 95 %) occurs, prepare fresh standards. If the recovery factor remains low, prepare new electrolyte, or new electrode solutions, or both. If the recovery factor still does not fall in the proper range, review the procedural details. 12.8 Calculate the three-point calibration curve.
9. Hazards 9.1 Consult the current version OSHA regulations, supplier's Material Safety Data Sheets, and local regulations for all materials used in this test method. 10. Sampling 10.1 Consult guidelines for taking samples from bulk in accordance with Practice D 3437. 11. Preparation of Apparatus 11.1 Carefully insert the quartz pyrolysis tube in the furnace and connect the oxygen and cartier gas lines. 11.2 Connect the boat drive to the pyrolysis tube and furnace. 11.3 Add the electrolyte solution to the titration cell, flushing several times. Maintain the electrolyte level at the highest marked line on the titration cell. 11.4 Add the proper solutions to the chamber of the working electrode and to the inner and outer chambers of the reference electrode. 11.5 Place the titration cell on the magnetic stirring device and connect the reference, working, and sensor electrodes to the controller. 11.6 Initiate a test titration of the titration cell according to the manufacturer's instructions. 11.7 Turn on the heating element of the pyrolysis furnace, and connect the dehydration tube to the outlet end of the pyrolysis furnace and to the cell. 11.8 Adjust the flow of the gases, the pyrolysis furnace temperature, and titration parameters to the desired operating conditions. Typical operational conditions are given in Table 1. 11.9 Prebake the sample boats to be used for the determination.
13. Procedure 13.1 Clean the syringe to be used for the sample. Flush it several times with the sample. Determine the chloride concentration in accordance with 12.4 through 12.6. 13.2 Chloride determination for the sample may require a change in titration parameters or adjustment in sample size, or both.
12. Calibration and Standardization 12.1 Using the chloride standard stock solution (see 8.18), make a series of three calibration standards covering the range of expected chloride concentration. 12.2 Into three 100-mL volumetric flasks, respectively pipet 1, 15, and 30 mL of chloride stock solution and dilute to the mark with methanol. (The standards are approximately 1 mg CI/L MeOH, 15 mg CI/L MeOH and 30 mg CI/L MeOH). 12.3 Adjust the operational parameters for a three-point calibration. If instrument is not equipped for a three-point calibration, manually record the recovery factors and calculate. 12.4 The sample s i z e can be determined either volumetrically, by syringe, or by mass. Make sure that the sample size is 80 % or less of the syringe capacity.
14. Calculation 14.1 Measurement utilizing volume and known specific gravity in milligrams per kilograms as follows: Chloride, mg/kg = ( M - B) x I-Lv x SG
14.2 Measurement utilizing weight of sample, considering dilution's in milligrams per kilograms as follows: Chloride, mg/kg = TABLE 2
TABLE 1 Parameter End Point Gain 1 Gain 2 Gain 3 Sensitivity Furnace temperature Oxygen flow Carder gas flow
(1)
RF
Operating Parameters Value 290 to 315 mV 0.5 to 5.0 1.0 to 10.0 1.0 to 15.0 0.5 to 1.5 mV 900 to 1100°C 200 mL/min 250 mL/min
(M - B) w
1 x --
(2)
RF
Densities of Common Hydrocarbons A
Component
Density
Temperature °C
Benzene Cyclohexane Ethylbenzene Isopropylbenzene Toluene m-Xylene o-Xylene
0.879 0.779 0.867 0.862 0.867 0.864 0.880
20 20 20 20 20 20 20
A Handbook of Chemistry and Physics, 40th Edition, "Table, Physical Constants of Organic Compounds', Chemical Rubber Co.
979
~) D 5808 where: M = measured chloride value, I.tg, B = blank chloride value, I.tg, v = sample injection volume, mL, w = weight of sample, g, SG = relative density, and RF = recovery factor = ~tg chlorides titrated theoretical value 15. Report 15.1 Report the chloride results as (mg/kg) of the.sample.
16. Precision and Bias s 16.1 Precision--The results from six laboratories were used to generate statistical data. Three values were recorded for each sample. The standard used to calibrate a standard curve was provided with the samples and a volume of 40 IxL was specified for all injections. For statistical calculations, the average value obtained on the neat (or blank) sample was s Supporting data are available from ASTM Headquarters. Request RR: Dl6-1017.
subtracted from the average value for the 1 mg/kg, 5 mg/kg, and 25 mg/kg samples. 16.2 Intermediate Precision--Two successive test results generated by the same laboratory, on the same sample, by the same operator, with the same test equipment should not be considered suspect unless the difference is greater than 0.7 mg/kg, with 95 % confidence. 16.3 Reproducibility--Two tests generated in different laboratories, on the same sample, should not be considered suspect unless the difference is greater than 1.3 mg/kg, with 95 % confidence. 16.4 Bias--The results from the analysis by 6 different laboratories of gravimetrically prepared standard addition samples indicated that this procedure does not contain a measurable amount of bias nor systematic error that could contribute to a difference between a population mean and the accepted true value. NOTE 4--Although the data in this report was compiled using an automatic boat drive, direct needle injections with a constant rate injector have been found to give satisfactoryresults. 17. Keywords 17.1 density; electrolysis; electrolyte; microcoulometry; potential; pyrolysis; recovery factor; relative density; titration; total chloride; volatilization
ANNEX
(Mandatory Information) AI. C O M B U S T I O N AND TITRATION M E A S U R E M E N T PRINCIPLES
A 1.1 Oxidative Pyrolysis: A 1.1.1 The sample is injected by a 50-~tL syringe, into a quartz boat, which is driven into a pyrolysis tube. Here, the sample is first volatilized, and then swept by a carrier gas further into the furnace, where it is combusted in a flow of oxygen gas. Hydrogen atoms from the breakdown of the hydrocarbon sample react with the chlorine atoms liberated by combustion to form hydrogen chloride. Hydrocarbons break down and form the following combustion products: X (CI) S
C H N p
---, --* 02 ~ ) 900"C ~ ~ --*
HX (HCI greater than C12) SO2 greater than SO3
C02
tube to remove water, and then introduced into the titration cell. AI.2 Titration: A I.2.1 Before hydrogen chloride is introduced into the cell, the electrolysis potential is kept at the end point potential, and the following equilibrium equation is maintained: Ag ¢:~ Ag + + c A l . 2 . 2 When hydrogen chloride is introduced into the cell, the following reaction takes place: HCi + Ag+ ~ AgCI + H +
AI.2.3 When the potential changes, electrolysis current is applied to the working electrode to generate silver ions. Thus, the silver ions consumed are replaced coulometrically. The total current applied is a measure of the chlorine in the sample.
H20 NO, NO2 P205
A 1.1.2 These product gases are swept into a dehydration
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, if you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 1916 Race St., Philadelphia, PA 19103.
980
Designation: D 5842 - 95
Designation: MPMS Chapter 8.4
Standard Practice for Sampling and Handling of Fuels for Volatility Measurement 1 This standard is issued under the fixed designation D 5842; the number immediately following the designation indicates the year of original adoption or, in the ease of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (0 indicates an editorial change since the last revision or re,approval.
MPMS Chapter 8.2--Standard Practice for Automatic Sampling of Liquid Petroleum and Petroleum Products MPMS Chapter 8.3uStandard Practice for Mixing and Handling of Liquid Samples of Petroleum and Petroleum Products
1. Scope 1.1 This practice covers procedures and equipment for obtaining, mixing, and handling representative samples of volatile fuels for the purpose of testing for compliance with the standards set forth for volatility related measurements applicable to light fuels. The applicable dry vapor pressure equivalent range of this practice is 13 to 105 kPa (2 to 16 psia). 1.2 This practice is applicable to the sampling, mixing, and handling of reformulated fuels including those containing oxygenates. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safi,ty and health practices and determine the applicability of regulatory limitations prior to use. 1.4 The values stated in acceptable metric units are to be regarded as the standard except in some cases where drawings may show English measurements which are customary for that equipment.
3. Terminology 3.1 Descriptions of Terms Specific to This Standard: 3.1.1 bottom sampleua sample obtained from the material at the bottom of the tank, container, or line at its lowest point. 3.1.1.1 DiscussionmIn practice the term bottom sample has a variety of meanings. As a result, it is recommended that the exact sampling location (for example, 15 cm [6 in.] from the bottom) should be specified when using this term. 3.1.2 dead legs--sections of pipe that, by design, do not allow for the flow of material through them. 3.1.2.1 DiscussionmDead legs are not suitable for obtaining representative samples. 3.1.3 relieflinesnsections of pipe that lead to a pressure/ vacuum relief valve. 3.1.3.1 Discussion--Relief lines are not suitable for obtaining representative samples. 3.1.4 stand pipes--vertical sections of pipe or tubing extending from the gaging platform to near the bottom of tanks that are equipped with external or internal floating roofs. Stand pipes also may be found on ships and barges. 3.1.4. l Discussion--Stand pipes which are not slotted or perforated will not yield representative samples. Further information on proper stand pipe design is given in 6.4.3. 3.1.5 Other sample definitions are given in Practice D 4057.
2. Referenced Documents 2.1 A S T M Standards: D323 Test Method for Vapor Pressure of Petroleum Products (Reid Method) 2 D4057 Practice for Manual Sampling of Petroleum and Petroleum Products 3 D 4953 Test Method for Vapor Pressure of Gasoline and Gasoline-Oxygenate Blends (Dry Method) 4 D 5190 Test Method for Vapor Pressure of Petroleum Products (Automatic Method) 4 D 5191 Test Method for Vapor Pressure of Petroleum Products (Mini Method) 4 2.2 API Documents: MPMS Chapter 8--Definitions MPMS Chapter 8.1--Standard Practice for Manual Sampling of Petroleum and Petroleum Products
4. Summary of Practice 4.1 It is necessary that the samples be representative of the fuel in question. The basic principle of each sampling procedure involves obtaining a sample in such a manner and from such locations in the tank or other container that the sample will be representative of the fuel. A summary of the sampling procedures and their application is presented in Table 1. Each procedure is suitable for sampling a material under definite storage, transportation, or container conditions. The precautions required to ensure the representative character of the samples are numerous and depend upon the tank, carder, container, or line from which the sample is being obtained, the type and cleanliness of the sample container, and the sampling procedure that is to be used.
i This practice is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee I:)02.02 on Static Petroleum Measurement. Current edition approved Nov. 10, 1995. Published February 1996. 2 Annual Book of ASTM Standards, Vol 05.01. 3 Annual Book of A S T M Standards, Vol 05.02. 4 Annual Book of A S T M Standards, Vol 05.03. S Available from the American Petroleum Institute, 1220 L St., NW, Washington, DC 20005.
981
(@) D 5842 TABLE 1
Summary of Gasoline Sampling Procedures and
use the clean procedure described in 6.4. 6.3 Time and Place of Sampling." 6.3.1 Storage Tanks--When loading or discharging fuels, take samples from both shipping and receiving tanks, and from the pipelines if required. 6.3.2 Ship or Barge Tanks--Sample each product after the vessel is loaded or just before unloading. 6.3.3 Tank Cars--Sample the product after the car is loaded or just before unloading.
Applicability Type of Container
Storage tanks, ship and barge
Procedure
Paragraph
all-levelssampling
7.2.1.2
running sample upper, middle and lower
7.2.1.2 7.2.1.2
tanks, tank cars, tank trucks
samples top sample Storage tanks with taps Pipes and lines
Retail outlet and wholesale purchasar-consumar facility storage tanks
grab sampling tap sampling line sampling automatic sampling time proportional flow proportional grab sampling nozzle sampling
7.2.1.2 7.5 7.2.2 7.3 7.4 7.4.1 7.4.2 7.5 7.6
NOTE l--Time, place, and other details of sampling not covered in this practice are normally determined by contractual agreement or regulatory requirements.
5. Significance and Use 5.1 The dry vapor pressure equivalent (DVPE) of volatile motor fuels is regulated by federal and state air pollution control agencies. In order to meet the letter of these regulations, it is necessary to sample, handle, and test these products in a very precise manner. 6. General Comments
6.1 Sample Containers: 6.1.1 Sample containers are clear or brown glass bottles, fluorinated high-density polyethylene bottles, or metal cans. The clear glass bottle is advantageous because it is easily examined visually for cleanliness, and also makes visual inspection of the sample for free water or solid impurities possible. The brown glass bottle affords some protection from light. The only cans acceptable are those with the seams soldered on the exterior surface. 6.1.2 Cork stoppers, or screw caps of plastic or metal, are used for glass bottles; screw caps with inserted seals only are used for cans to provide a vapor-tight closure seal. Corks must be of good quality, clean, and free from holes and loose bits of cork. Never use rubber stoppers. Contact of the sample with the cork can be prevented by wrapping tin or aluminum foil around the cork before forcing it into the bottle. Screw caps must be protected by a cork disk faced with tin or aluminum foil, an inverted cone polyseal or other material that will not affect petroleum or petroleum products. The fluorinated bottles are supplied with polypropylene screw caps. 6.1.3 Sample size is dictated by the test method to be used. One litre (32 oz) bottles or cans are generally used for manual vapor pressure testing. The mini-vapor pressure methods need a much smaller sample and it can be taken in a 125 mL (4 oz) bottle. See Fig. 10. 6.1.4 All sample containers must be absolutely clean and free of foreign matter. Before reusing a container, wash it with strong soap solution, rinse it thoroughly with tap water, and finally with distilled water. Dry completely, stopper, or cap the container immediately. 6.2 Sampling Apparatus--Sampling apparatus is described in detail under each of the specific sampling procedures. Clean, dry, and free all sampling apparatus from any substance that might contaminate the material. If necessary, 982
6.4 ObtainingSamples: 6.4.1 Directions for sampling cannot be made explicit enough to cover all cases. Extreme care and good judgment are necessary to ensure samples that represent the general character and average condition of the material. Use lint-free wiping cloths to prevent contaminating samples. 6.4.2 Many petroleum vapors are toxic and flammable. Avoid breathing them or igniting them from an open flame or a spark. Follow all safety precautions specific to the material being sampled. 6.4.3 Do not sample dead legs or relief lines. Do not sample stand pipes that are not slotted or perforated! Figure 1 is an example of an adequately slotted stand pipe. At a minimum, the stand pipe should have two rows of slots slightly staggered in the vertical plane. 6.4.4 Rinse or flush sample containers with product and allow it to drain before drawing the sample. If the sample is to be transferred to another container (for testing other than DVPE), the sampling apparatus also is rinsed with some of the product and drained. When the sample is emptied into this container, upend the sampling apparatus into the opening of the sample container. 6.5 Handling Samples: 6.5.1 Protect all samples of light fuels from evaporation. The sampling apparatus is the sample container for vapor pressure. Keep the container tightly closed after the sample is collected. Leaking sample containers are not suitable for testing. Cool volatile samples to 0 to I*C (32 to 34"F) after delivery to the laboratory and before opening the container. Maintain at this temperature throughout transfer and handling, if at all possible. 6.5.2 Never completely fill a sample container. Fill the container to 70 to 85 % capacity to allow adequate room for
,,,,
@!i FiG. 1
Slotted Stand Pipe
~
D 5842
expansion. Subsequent testing for vapor pressure requires this level of container fill. 6.5.3 The first sample aliquot removed is for vapor pressure testing. The remaining sample in the container is not suitable for a vapor pressure determination but is suitable for other testing. 6.6 Shipping SamplesmTo prevent loss of liquid and vapors during shipment, place internal seals in the metal containers, screw the caps down tightly and check for leakage. Observe all shipping regulations applying to the transportation of flammable liquids. 6.7 Labeling Sample Containers--Label the container immediately after a sample is obtained. Use waterproof and oilproof ink or a pencil hard enough to dent the tag, since soft pencil and ordinary ink markings are subject to obliteration from moisture, product, smearing, and handling. Typical label information includes the following information: 6.7.1 Date and time (the period elapsed during continuous sampling), 6.7.2 Name of the sample (location), 6.7.3 Name or number and owner of the vessel, car, or container, 6.7.4 Brand and grade of material; and 6.7.5 Reference symbol or identification number. 6.7.6 Labeling should conform to all applicable federal, state, and local labeling regulations. 7. Specific Sampling Procedures
7.1 Sampling Procedures--The standard sampling procedures described in this practice are summarized in Table 1. Alternative sampling procedures can be used if a mutually satisfactory agreement has been reached by the party(ies) involved and such agreement has been put in writing and signed by authorized officials. 7.2 Tank Sampling." 7.2.1 Bottle Sampling--The bottle sampling procedure is applicable for sampling fuels of 105 kPa (16 psia) Reid equivalent vapor pressure or less in tank cars, tank trucks, shore tanks, ship tanks, and barge tanks. 7.2.1.1 ApparatusmA suitable sampling bottle as shown in Fig. 3 is required. Recommended diameter of the opening
/F-t" F 1 5 cm (6")
Outlet
Top sample Upper sample
Upper third
X
Middlesample
Middle third
X
Lowersample Outlet sample
Lower third
~
Clove hitch Eyelet
C:,~her Cork arrangements
1-Litre (1 qt ) Sample WeightedCage (can be fabricated to fit any size bottle)
A
B FIG. 3
Assembly for Bottle Sampling
in the boric or sample thief is 19 m m (3/4 in.). 7.2.1.2 Procedure." (a) All-levels SamplemLower the weighted, stoppered bottle (see Fig. 3) as near as possible to the draw-off level, pull out the stopper with a sharp jerk of the cord or chain and raise the bottle at a rate so that it is 70 to 85 % full as it emerges from the liquid. (b) Running Sample--Lower the stoppered container (with a hole or slot in the stopper) at a uniform rate as near as possible to the level of the bottom of the outlet connection or swing line and immediately raise the bottle to the top of the fuel at a rate of speed such that it is 70 to 85 % full when withdrawn from the liquid. NOTE 2--Running or all-level samples are not necessarily representative because the tank volume may not be proportional to the depth and because the operator may not be able to raise the sampler at the required rate. (c) Upper,Middle, and LowerSamples--Lowerthe weighted, stoppered bottle to the proper depths (Fig. 2) as follows:
Hatch
X~-~
"•-
Bottom sample NOTE--The outlet sample location shown applies only to tanks with side outlets, It does not applywhen the outletcomesfrom the floor of the tank or turns down into a sump. FIG. 2 Tank Sampling Depths
983
upper sample
middle of upper third of the tank contents
middle sample lowersample
middle of the tank contents middle of the lowerthird of the tank contents
At the selected level, pull out the stopper with a sharp jerk of the cord or chain and allow the bottle to fill completely, as evidenced by the cessation of air bubbles. When full, raise the bottle, pour offa small amount (15 to 30 %), and stopper immediately. (d) Top SamplewObtain this sample (Fig. 2) in the same manner as specified for an upper sample but at 150 mm (6 in.) below the top surface of the tank contents. (e) HandlingmCap and label bottle samples immediately after taking them, and deliver to the laboratory in the original sampling bottles. Multiple samples must be tested individually for vapor pressure. A composite sample is acceptable for other analytical tests. Inverting the sample container can aid in leak detection. Sample may be placed in ice immediately for cooling if practical (see Section 10). 7.2.2 Tap SamplingmThe tap sampling procedure is applicable for sampling liquids of 105 kPa (16 psia) DVPE,
(~
D 5842
Optional--~
Optional-~
¢111
;-..52 ¢11.~ r i l l
"//z ~./ I.t
Line o r tank wall
,i
-
Line or tank wall ------I~-~/~
ii
\
f/l,
¢'//,,
~"/z
NOTE--Probesare optional. FIG. 4
Assemblies for Tap Sampling
or less, in tanks that are equipped with suitable sampling taps or lines. This procedure is recommended for volatile stocks in tanks of the breather and balloon roof type, spheroids, floating roof tanks, and so forth. The assembly for tap sampling is shown in Fig. 4. 7.2.2.1 Apparatus: (a) Tank Taps--Equip the tank with at least three sampling taps placed equidistant throughout the tank height. A standard 1/4 in. pipe with a suitable valve is satisfactory. A sufficient number of sample taps are needed on the tank to make sampling possible at various levels. (b) Tube--Use a delivery tube that will not contaminate the product being sampled and is long enough to reach to the bottom of the sample container to allow submerged filling. (c) Tube Chiller Assembly (Optional)--If a sampling chiller is used, it is a coil of tubing immersed in an ice bath to chill a fuel sample as it is dispensed into the sample container. (d) Sample Containers--Use clean, dry glass bottles of convenient size and strength or metal containers to receive the samples. 7.2.2.2 Procedure--Before a sample is drawn, flush the sample tap and tube until approximately three times its volume has been purged. When sampling for Reid equivalent vapor pressure, the container must be chilled to a temperature as low as the material in the tank or to 0°C (32°F), whichever is greater (see sample chilling apparatus in Fig. 5). Filling the container and emptying it three times will meet this temperature requirement. Draw upper, middle, or lower samples directly from the respective taps after the flushing operation. Stopper or seal and cap, label the sample container immediately after filling and deliver it to the laboratory. 7.3 Line Sampling--The continuous sampling procedure is applicable for sampling liquids of 105 kPa (16 psia) Reid equivalent vapor pressure or less and semi-liquids in pipelines, filling lines, and transfer lines. The line sampling may be done manually or by using automatic devices. In order to take a representative sample from a line, the contents are
+~,',,,+,,,e,.."
Outlet / valve ,~ (-~ D i ':?~P°~O
i
'
To tank
va,v. •
Coppertubing~ 6 4 mmO D ) V ~
8m -
,, ,
,I
:
~
+? ~
Ou!lot~ ~
Totank Purgingvalve
Top view
I
FIG. 5
I
Cooling Bath for Reid Equivalent Vapor Pressure Sampling
mixed to ensure uniform distribution of all components and contaminants across the line. If it is necessary to condition the line, this is done four to six pipe diameters upstream of the sample point. 7.3.1 Apparatus: 7.3.1.1 Sampling Probe--The function of the sampling probe is to allow withdrawal of a representative portion of liquids. The apparatus assembly for dynamic line sampling is shown in Fig. 6. A probe is recommended for the sampling of static systems but it is not required. Probe designs that are commonly used are as follows: (a) A tube beveled at a 45" angle (Fig. 6a). (b A long-radius forged elbow or pipe bend with the end of the probe reamed to give a sharp entrance edge (Fig. 6b). (c) A closed-end tube with a round orifice spaced near the closed end (Fig. 6c). 7.3.1.2 Probe Location--The probe inlet is extended into the pipe to the center one-third of the pipeline cross-sectional area. The probe is inserted perpendicular to the direction of 984
~ End of probe closed orifice facing upstream
D 5842
2") pipe I D
~
Manufacturers standard
~T~o
1 ~ / 6 . 4 (V,¢mm-5 cm. -2") pipe ortubing
6.4 mm -5 cm (1/4"-2") pipe or tubing
diameter
valve
FIG. 6
45° bevel
11-4-(
U
m
To valve
Probes for Line Sampling
flow with the sample opening facing upstream. The sampling lines are kept as short as practicable and purged completely before any samples are taken. 7.3.1.3 Valves--To control the rate at which the sample is withdrawn, the probe or probes are fitted with ball, gate, needle, or large port valves. 7.4 Automatic Samplers--An automatic sampler includes not only the automatic sampling device that extracts the samples from the line, but also a suitable probe, connecting lines, auxiliary equipment, and a container in which the sample is collected. It must maintain sample integrity. Refer to API MPMS Chapter 8.2. Automatic samplers are classified as follows: 7.4. l Continuous Sampler, Time Cycle (Nonproportional) Type--A sampler designed so that it transfers equal increments of liquid from the pipeline to the sample container at uniform time increments. 7.4.2 Continuous Sampler, Flow-Responsive (Proportional) Type--A sampler designed to automatically adjust the sampling rate to be proportional to the flow rate of the stream. 7.4.3 Calibration--Prior to initial operation, the sample bite size must be verified to be within +5 % of the specification using an acceptable calibration procedure. Additionally, the required sample volume must be obtained during any sampling period so that the manufacturer's sampling interval is not exceeded. 7.4.4 Container--The container must be a clean, dry container of convenient size to receive the sample. All connections from the sample probe to the sample container must be free of leaks. The container is constructed in such a manner that it prevents evaporation loss. The construction must allow cleaning, interior inspection, and complete mixing of the sample prior to removal. A fixed volume type container is equipped with a pressure-relief device. 7.5 Grab or Spot Sampling--Purge approximately three volumes of product through the sample tap and tubine. Divert the sample stream to the sampling container to provide a quantity of sample that will be of sufficient size for analysis. 7.6 Nozzle Sampling--The nozzle sampling procedure is applicable for sampling light fuels from a retail type dispenser. 7.6.1 Apparatus--Sample containers conforming with Section 6 should be used. A spacer, if appropriate, and a 985
nozzle extension as shown in Figs. 7 and 8 are used when nozzle sampling. 7.6.2 Procedure--Immediately after fuel has been delivered from the pump and the pump has been reset, attach a spacer (Fig. 7), if needed, to the pump nozzle (vapor recovery type). Insert nozzle extension (Fig. 8) into the previously chilled sample container and insert the pump nozzle into the extension with slot over the air bleed hole. Fill the sample container slowly through the nozzle extension to 70 to 85 % full (Fig. 9). Remove the nozzle extension. Insert the seal and cap or stopper into the sample container at once. Check for leaks. If a leak occurs, discard the sample container and resample. If the sample container is leak tight, label the container and deliver it to the laboratory. 8. Special Precautions and Instructions 8.1 Precautions--Vapor pressures are extremely sensitive to evaporation losses and to slight changes in composition. When obtaining, storing, or handling samples, observe the necessary precautions to ensure the samples are representa-
Use this slot for leaded ~- gasolineor fuels
Use this slot for
unleadedgasoline~
////A,"
',:
/////!;--','..' +i
i [
P
: _
1
I
1'/,
+
NOTE1--Makefrom +/4in. flat non-fen'ousmetal. NOTE2--All dimensionsare in inches. NOTE3--Breakall edgesand comers. FIG. 7 Spacer for Nozzle Sampling
21
-I
1@) D 5842
Use this end ~ for leaded __J gasolineand ~
--|
--7 o,.oo0 . ~--fo~.,ea~
I
E[ I_ f
I~
/
J
IJ
1
;!~ ~ - -~~ - ' - I, '-~--)
-~l
_1
11/2'
-~
gaso,,ne
f~
=,
4
11/;~
5
NOTE 1--Use ~/4 in. Schedule 80 non-ferrous pipe. NOTE 2--All dimensions are in inches. NOTE 3--All tolerances ere + 1/1=o. A Recommend 30*. e Inside diameter schedule 80 non-ferrous pipe. FIG. 8
Extension for Nozzle Sampling
tive of the product and satisfactory for Reid equivalent vapor pressure tests. Never manually prepare composite samples for this test. Make certain that containers that are to be shipped by common carrier conform to applicable federal, state, and local regulations. When flushing or purging lines or containers, observe the pertinent regulations and precautions against fire, explosion, and other hazards. Collect all line flushes and bottle rinses for proper recovery or disposal. 8.2 Sample Containers--Use containers of sufficient strength to withstand the pressures to which they can be subjected, and of a type that will permit replacement of the cap or stopper with suitable connections for transferring the sample to the gasoline chamber of the vapor pressure apparatus.
\
sp
Nozz,e__ Nozz,._
9. Keywords NozzleWithout VaporRecovery
9.1 dry vapor pressure; fuels; gasoline; gasoline sampling; petroleum products; sampling; sample handling; sampling of volatile products; vapor pressure; volatility
FIG. 9
986
NozzleWith VaporRecovery
Assembly for Nozzle Sampling
(~lJ~ D 5842 Heightof 4 oz. bottle
•
~
I"
-
~
Tappedand threadedto fit 4 OZ. bottle n e ~
1/2" 0"~0~"
-
_J lots wi~ 3/18" radius at the top
NOTE I~AII dimensionsare in inches. NOTE 2--All decimal dimensionsrepresent minimumand maximum. NOTE 3inTolerance for all other dimensionsis + l/a=in. NOTE 4reMade of non-ferrous material, unaffected by gasoline. Scale--0.700 in. = 1 in. FIG. 10 Nozzle Extension for Nozzle Sampling with 4 oz Bottle
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the vafldity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and ff not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, ff you fee/that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohocken, PA 19428.
987
(1~,) Designation: D 5845 - 95
Standard Test Method for Determination of MTBE, ETBE, TAME, DIPE, Methanol, Ethanol and tert-Butanol in Gasoline by Infrared Spectroscopy I This standard is issued under the fixed designation D 5845; the number immediately foilowin8 the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (0 indicates an editorial change since the last revision or reapproval.
oxygen-selective flame ionization detection)
1. Scope 1.1 This test method covers the determination of methanol, ethanol, tert-butanol, methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), and diisopropyl ether (DIPE) in gasoline by infrared spectroscopy. The test method is suitable for determining methanol from 0.1 to 6 mass %, ethanol from 0.1 to 11 mass %, tert-butanol from 0.1 to 14 mass %, and DIPE, MTBE, ETBE and TAME from 0.1 to 20 mass %. 1.2 SI units of measurement are preferred and used throughout this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
3. Terminology 3.1 Definitions: 3.1.1 oxygenate--an oxygen-containing organic compound, which may be used as a fuel or fuel supplement, for example, various alcohols or ethers. 3.1.2 multivariate calibration--a process for creating a calibration model in which multivariate mathematics is applied to correlate the absorbances measured for a set of calibration samples to reference component concentrations or property values for the set of samples. The resultant multivariate calibration model is applied to the analysis of spectra of unknown samples to provide an estimate of the component concentration or property values for the unknown sample.
2. Referenced Documents 2.1 A S T M Standards: D 1298 Practice for Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method 2 D 4052 Test Method for Density and Relative Density of Liquids by Digital Density Meter 3 D4057 Practice for Manual Sampling of Petroleum and Petroleum Products 3 D 4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards 3 D 4815 Test Method for Determination of MTBE, ETBE, TAME, DIPE, tert-Amyl Alcohol, and C I to C4 Alcohols in Gasoline by Gas Chromatography 4 D 5599 Test Method for Determination of Oxygenates in Gasoline by Gas Chromatography and Oxygen Selective Flame Ionization Detector4 E 1655 Practice for Infrared, Multivariate, Quantitative Analysiss 2.2 Other Standard: GC/OFID EPA Test Method--Oxygen and Oxygenate Content Analysis6 (by way of gas chromatography with
4. Summary of Test Method 4.1 A sample of gasoline is introduced into a liquid sample cell. A beam of infrared light is imaged through the sample onto a detector, and the detector response is determined. Regions of the infrared spectrum are selected for use in the analysis by either placing highly selective bandpass filters before or after the sample or mathematically selecting the regions after the whole spectrum is obtained. A multivariate mathematical analysis is carried out which converts the detector response for the selected regions in the spectrum of an unknown to a concentration for each component. 5. Significance and Use 5.1 Alcohols and ethers are added to gasoline to produce a reformulated lower emissions gasoline. Alcohols and ethers may also be added to gasoline to increase the octane number. Type and concentration of various oxygenates are specified and regulated to ensure acceptable commercial gasoline quality. Driveability, vapor pressure, phase separation, and evaporative emissions are some of the concerns associated with oxygenated fuels. 5.2 This test method is faster, simpler, less expensive and more portable than current methods. 5.3 This test method may be applicable for quality control in the production of gasoline. 5.4 This test method is not suitable for testing for compliance with federal regulations. 6
i This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct t~sponsibility of Subcommittee D02.04.OF on Absorption Spectroscopic Methods. Current edition approved Oct. 10, 1995. Published December 1995. 2 Annual Book of A S T M Standards, Vol 05.01. 3 Annual Book of A~'TM Standards, Vol 05.02. ( Annual Book of ASTM Standards, Voi 05.03. s Annual Book of A S T M Standards, Vol 03.06. Code of Federal Regulations, Part 80 of Title 40, Section 80.46(g); also published in the Federal Register, Volume 59, No. 32, February 16, 1994, p 7828.
988
~
D 5845 to testing. This can be accomplished by storage in an appropriate ice bath or refrigerator at 0 to 5"C. 8.1.4 Do not test samples stored in leaky containers. Discard and obtain a new sample if leaks are detected. 8.1.5 Perform the oxygenate determination on fresh samples from containers that are at least 80 % full. If sample containers are less than 80 % full or have been opened and sampled multiple times, a new sample shall be obtained. 8.2 Sample Handling During Analysis: 8.2.1 Prior to the analysis of samples by infrared spectroscopy, the samples should be allowed to equilibrate to the temperature at which they should be analyzed (15 to 38"C). 8.2.2 After withdrawing the sample, reseal the container, and store the sample in an ice bath or a refrigerator at 0 to 5"C.
5.5 False positive readings for some of the samples tested in the round robin were sometimes observed. As only extreme base gasolines were tested in the round robin, no definitive statement can be made as to the expected frequency or magnitude of false positives expected in a wider range of base gasolines.
6. Apparatus
6.1 Mid-IR Spectrometric Analyzer, of one of the following types:
6.1.1 Filter-based Mid-IR Test Apparatus--The type of apparatus suitable for use in this test method minimally employs an IR source, an infrared transmission cell or a liquid attenuated total internal reflection cell, wavelength discriminating filters, a chopper wheel, a detector, an A-D converter, a microprocessor, and a sample introduction system. 6.1.2 Fourier Transform Mid-IR Test Apparatus--The type of apparatus suitable for use in this test method employs an IR source, an infrared transmission cell or a liquid attenuated total internal reflection cell, a scanning interferometer, a detector, an A-D converter, a microprocessor and a sample introduction system. 6.1.3 Dispersive Mid-IR Test Apparatus--The type of apparatus suitable for use in this test method minimally employs an IR source, an infrared transmission cell or a liquid attenuated total internal reflection cell, a wavelength dispersive element such as a grating or prism, a chopper wheel, a detector, an A-D converter, a microprocessor and a sample introduction system.
9. Preparation, Calibration, and Validation of Calibration of the Infrared Test Apparatus 9.1 Preparation--Prepare the instrument for operation in accordance with the manufacturer's instructions. 9.2 Calibration--Each instrument must be calibrated by the manufacturer or user in accordance with Practice E 1655. This practice serves as a guide for the multivariate calibration of infrared spectrometers used in determining the physical characteristics of petroleum and petrochemical products. The procedures describe treatment of the data, development of the calibration, and validation of the calibration. Note that bias and slope adjustments are specifically not recommended to improve calibration or prediction statistics for IR multivariate models. 9.3 Validation of Calibration--The calibration of the instrument must be validated in order to ensure that the instrument accurately and precisely measures each oxygenate in the presence of typical gasoline compounds or other oxygenates that, in typical concentrations, present spectral interferences. General classes of compounds that will cause interferences include aromatics, branched aliphatic hydrocarbons, and other oxygenates. 9.3.1 Preparation of Validation Standards--The minimum matrix of validation standards is presented in Table 1. Additional validation standards may be added. Prepare multicomponent validation standards of the oxygenates by mass according to Practice D 4307 or appropriately scaled for larger blends. To ensure that there is minimum interference from any oxygenate present in the base gasolines, a gas chromatographic analysis of the base gasolines must be performed to ensure the absence of oxygenates (use Test Methods D 4815, D 5599, or GC-OFID). To ensure the insensitivity of the calibration to the hydrocarbon matrix of the base gasolines, the base gasolines used for preparation of the validation standards should be different from the base gasoline(s) used for preparation of the calibration standards. To minimize the evaporation of light components, adjust the temperature of all chemicals and gasolines used to prepare standards to between 5 and 20°C. None of the samples or base gasolines used in the validation of calibration may be used for the calibration (or recalibration) of an instrument. 9.3.2 Analysis of Validation Standards--The validation standards should be analyzed by the procedure specified in Section 11. If necessary, results should be converted from
7. Reagents and Materials
7. l Standards for Calibration and Quality Control Check Solutions--Use of chemicals of at least 99 % purity is highly recommended when preparing calibration and quality control check samples. If reagents of high purity are not available, an accurate assay of the reagent must be performed using a properly calibrated GC or other techniques (for example, water determination). 7.1.1 Base gasolines containing no oxygenates, 7.1.2 Methanol, 7.1.3 Ethanol, 7.1.4 tert-Butanol, 7.1.5 Methyl tert-butyl ether, MTBE, 7.1.6 Ethyl tert-butyl ether, ETBE, 7.1.7 tert-Amyl methyl ether, TAME, and 7.1.8 Diisopropyl ether, DIPE. Note 1: Warning--These materials are flammable and may be harmful if ingestedor inhaled.
8. Sampling and Sample Handling
8.1 General Requirements: 8.1.1 Gasoline samples must be handled with meticulous care to prevent evaporative loss and composition changes. 8.1.2 Gasoline samples to be analyzed by the test method shall be obtained using method(s) specified by governmental regulatory agencies or by the procedures outlined in Practice D 4057 (or equivalent). Do not use the "Sampling by Water Displacement" method as some alcohols or ethers might be extracted into the water phase. 8.1.3 Protect samples from excessive temperatures prior 989
(1~ D 5845 TABLE 1 NOTs--All concentrations are mass %. Sample Base GasA MTBE 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
A A A A A A A A A A A A A A A A A A B B B B B B B B B B B B B B B B B B
Minimum Matrix for Validation of Calibration TAME
ETBE
Ethanol
Methanol
t-Butanol
1.5
2
DIPE
10 5 16.5 9 18.5 12
4
1.25
17 9.5
4 6.5 3.5
3
12 6
9 7 5
16.5 10
7 6 3
3 5 1.5
3 2 7 g 6
2
5
2
14 10
1.5
2
16.5 11
4
15.5 8
5 5 3.5
3
12 8
5 6 2
16.5 9
6 4 2
3 8 1.5
1.5 4
8
1.5
,~ Bsee gasoline A should be a gasoline with at least 60 % slkylate. A suggasted recllpefor _h=___*e_ gasoline A IS 60 '/, SlO/late, 30 % U ranga reformate, and 10 "/. light straight run. Base gasoline B should be a gaanllne with at least 60 ~; ful range reforrnete. A suggested reolpe for balm gasoine B Is 60 li full range refonnete, 30 ~ FCC gasoline, and 10 "/. light straight run.
volume to mass % by the calculations described in Section 12.
9.3.3 Criteriafor l/alidation of Calibration--The calibration is considered to be validated if the following specifications are all met: 9.3.3.1 Accuracyof Each Oxygenate--Analysis of each of the oxygenates in each of the validationstandards must be within the criteria established in Table 2. If it is known that an analyte is not present in a particular validation sample, the value determined for that analyte must be less than the criteria also established in Table 2. 9.3.3.2 Overall Accuracy--The standard error of prediction (SEP) for each analyte summed over all samples in the TABLE 2
Maximum Error Allowed for Validation of Calibration
Oxygenate
MTBE TAME ETBE Ethanol Methanol t-Butenol OIPE
Error Oxygenate Is Known To Be Present, mass %, msx
1.5 2.0 1.2 0.9 0.6 0.9 1.2
validation set must be within the criteria established in Table 3. 9.3.3.3 OverallRepeatability--Each sample of the validation set must be run twice. Repeat determinations of any sample can differ by no more than 0.3 mass %. 9.3.4 Frequency of Validation--Once the calibration of the instrument has been validated, it need only be revalidated when either the instrument has been recalibrated due to repair or when the quality control check samples are outside of the test tolerance. 10. Quality Control Standards 10.1 Confirm the proper operation of the instrument each day it is used by analyzing at least one quality control TABLE 3
Error When Oxygenate Is Not
Maximum Standard Error of Prediction Allowed for Validation of Calibration
Present,mass ~;, max
Oxygenate
SEP Summed Over Samples Containing The O x y ~ t e , max
SEP Summed Over All Samples In The VaUdatkxl Set, max
0.9 1.8 1.9 0.6 0.3 0.9 0.9
MTBE TAME ETBE Ethanol Methanol t.Butanol DIPE
0.9 1.2 0.75 0.4 0.25 0.55 0.6
0.5 0.9 0.6 0.25 0.15 0.45 0.35
990
~
D 5845 TABLE 5 Pertinent Physical Constants
standard of known oxygenate content for each oxygenate to be determined. These standards should be made up by mass according to Practice D 4307 and should be at the expected concentration level for that oxygenate. The recommended quality control standard concentrations are found in Table 4. 10.2 The individual oxygenate values obtained must agree within +5 % relative of the values in the prepared quality control standard (for example, MTBE 14.0 ¢ 0.7 mass %) or to within +0.3 mass % absolute, whichever is greater (for example, methanol 4.0 ¢ 0.3 mass %). If the individual values are outside the specified range, recallbrate the instrument according to the procedures in 9.2. The quality control standards should not be used for the calibration or recalibration of the instrument. Do not analyze samples without meeting the quality control specifications.
5.41 7.77 12.5 14.9 17.2 17.2 17.2
5.76 9.26 11.0 12.8 12.8 12.8
mass % mass % mass ',~ mass ~ mass % mass ~
mass mass mass mass mass mass mass
% %
67-56-1 64-17-5 75-65-0 1634-04-4 108-20-3 637-92-3 994-.05-8
32.04 46.07 74.12 88.15 102.18 102.18 102.18
0.7963 0.7939 0.7922 0.7460 0.7300 0.7452 0.7750
Wto t = ~ [(m I X 16.0 x
Ni)/MI]
(2)
total mass % oxygen in the fuel, mass % for each oxygenate, atomic mass of oxygen, number of oxygen atoms in the oxygenate molecule, and M~ = molecular mass of the oxygenate molecule as given in Table 5. 13. Report 13.1 Report results of each oxygenate and the total oxygen to the nearest 0.1 mass %.
14. Precision and Bias7 14.1 The precision of the method as obtained by statistical examination of interlaboratory results is as follows: 14.2 Repeatability---T~e difference between successive test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method exceed the following values only in one case in twenty: Oxygenate MTBE TAME ETBE Ethanol Methanol t-Butanol DIPE Total Oxygen Content
Concentration to Attaln
4.00 mass %
Methanol Ethanol
where: Wto, = m~ = 16.0 = N~ =
TABLE 4 Recommended Concentrations for Individual Quality Control Standards
Methanol Ethanol tort-Butanol MTBE TAME DIPE ETBE
Relative Density, 15.56"C
D~. = relative density at 15.56°C of the individual oxygenate as found in Table 5, Df = relative density of the fuel at 15.56°C under study as determined by Practice D 1298 or Test Method D 4052. If the density has not been measured, an assumed density of 0.742 should be used. 12.2 Total Mass % Oxygen--To determine the total oxygen content of the fuel, sum the mass % oxygen contents of all oxygenate components determined above according to Eq 2:
:
2.7 mass % O
Molecular Mass
MTBE DIPE ETBE TAME
12. Calculation 12.1 Conversion to Mass Concentration of Oxygenates--If the instrument readings are in volume % for each component, convert the results to mass % according to Eq 1: m: VI (Dl/Dy) (1) where: m~ = mass % for each oxygenate to be determined, V,. = volume % of each oxygenate,
2.0 mass % O
GAS Number
tort-Butanol
11. Procedure 11.1 Equilibrate the samples to between 15 and 38°C before analysis. 11.2 Follow the manufacturer's instructions for estabfishing a baseline for the instrument, introducing a sample into the sample cell and operating the instrument. If the instructions call for a non-oxygenated gasoline to be used in establishing the baseline, use a non-oxygenated gasoline that is different from the non-oxygenated gasolines used in the preparation of either calibration standards, validation of calibration standards, or quality control standards. 11.3 Thoroughly clean the sample cell by introducing enough sample to the cell to ensure the cell is washed a minimum of three times with the test solution. 11.4 Establish that the equipment is running properly by running the quality control standards prior to the analysis of unknown test samples (see Section 10). 11.5 Introduce the sample in the manner established by the manufacturer. Obtain the concentration reading produced by the instrument.
Oxygenate
Component
Repeatability (mass %) 0.13 0.13 0.15 O.13 0.07 O.! 0 0.14 0.05
14.3 Reproducibility--The difference between two single and independent results, obtained by different operators working in different laboratories on identical test materials would, in the long run, exceed the following values only in one case in twenty:
3.5 mass ~ O 10.1 mass %
Y. %
7 Supporting data available from ASTM Headquarters. Request D02-1374.
991
~ Oxygenate MTBE TAME ETBE Ethanol Methanol t-Butanol DIPE Total OxygenContent
D 5845
Reproducibility(mass %) 0.98 1.36 0.77 0.59 0.37 0.59 0.79 0.30
samples tested in the r o u n d r o b i n a n d since a wide range o f base gasolines was n o t tested, it is not possible to offer a definitive s t a t e m e n t o f bias except to note that biases were observed in the r o u n d robin.
Ke~vords 15.1 alcohols; diisopropyl ether; ethanol; ethers; ethyl t e r t - b u t y l ether; methanol; methyl t e r t - b u t y l ether; motor gasoline; oxygenate; t e r l - a m y l methyl ether; t e r t - b u t a n o ] 15.
14.4 Bias--No consistent bias was observed with the
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reepproved or withdrawn. Your comments are Invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohockan, PA 19428.
992
(~1~l~ Designation: D 5853 - 95 Standard Test Method for Pour Point of Crude Oils 1 This standard is issued under the fixed designation D 5853; the number immedmtely following the designation indicates the year of original adoption or, in the case of revision, the year of last revismn. A number in parentheses indicates the year of last reapproval. A superscript epsilon (0 indicates an editorial change since the last revision or reapproval.
prescribed treatment designed to enhance gelation of wax crystals and solidification of the test specimen. 3.1.3 minimum (lower) pour point, n--the pour point obtained after the test specimen has been subjected to a prescribed treatment designed to delay gelation of wax crystals and solidification of the test specimen.
1. Scope 1.1 This test method covers two procedures for the determination of the pour point temperatures of crude oils down to -36"C. One method provides a measure of the maximum (upper) pour point temperature (Procedure A) and is described in 9.1; the other method provides a measure of the minimum (lower) pour point temperature (Procedure B) and is described in 9.2. 1.2 The use of this test method is limited to use for crude oils. Pour point temperatures of other petroleum products can be determined by Test Method D 97. 1.3 This standard does not purport to address all of the
4. Summary of Test Method 4.1 After preliminary heating, the test specimen is cooled at a specified rate and examined at intervals of 3"C for flow characteristics. The lowest temperature at which movement of the test specimen is observed is recorded as the pour point.
safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific
5. Significance and Use 5.1 The pour point of a crude oil is an index of the lowest temperature of handleability for certain applications. 5.2 This is the only pour point method specifically designed for crude oils. 5.3 The maximum and minimum pour point temperatures provide a temperature window where a crude oil, depending on its thermal history, might appear in the liquid as well as the solid state. 5.4 The test method can be used to supplement other measurements of cold flow behavior. It is especially useful for the screening of the effect of wax interaction modifiers on the flow behavior of crude oils.
hazard statements, see Section 7.
2. Referenced Documents
2.1 ASTM Standards: D 97 Test Method for Pour Point of Petroleum Products 2 D 130 Test Method for Detection of Copper Corrosion from Petroleum Products by the Copper Strip Tarnish Test2 D323 Test Method for Vapor Pressure of Petroleum Products (Reid Method) 2 D4057 Practice for Manual Sampling of Petroleum and Petroleum Products 3 D 4177 Practice for Automatic Sampling of Petroleum and Petroleum Products 3 E l Specification for ASTM Thermometers4 E 77 Test Method for Inspection and Verification of Thermometers4
6. Apparatus 6.1 Pour Point Test Apparatus Assembly (see Fig. 1): 6.1.1 Test Jar, cylindrical, of clear glass, fiat bottomed, outside diameter 33.2 to 34.8 mm, and height 115 to 125 ram. The inside diameter of the jar can range from 30.0 to 32.4 mm, within the constraint that the wall thickness shall be no greater than 1.6 mm. The jar shall have a line to indicate a sample height 54 + 3 mm above the inside bottom. The inside of the test jar (up to the mark) shall be visibly clean and free of scratches. 6.1.2 Thermometers, having ranges shown in the following table and conforming to the requirements prescribed in Specification E 1 for thermometers:
3. Terminology 3.1 Descriptions of Terms Specific to This Standard: 3.1.1 pour point, n - - t h e lowest temperature at which movement of the test specimen is observed under the conditions of the test. 3.1.2 maximum (upper) pour point, n D t h e pour point obtained after the test specimen has been subjected to a
Thermometer
' This test method is under the jurisdiction of ASTM Committee D-2 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.07 on Flow Properties. Current edition approved Oct. 10, 1995. Published December 1995. 2 Annual Book of ASTM Standards, Vol 05.01. 3 Annual Book of ASTM Standards, Vol 05.02. 4 Annual Book of ASTM Standards, Vol 14.03. s This pressure vessel is identical to the pressure vessel described in Test Method D 130.
Thermometer
Temperature Range
High cloud and pour Low cloud and pour Melting point
- 3 8 to +50"C -80 to +20"C +32 to + 127°C
Number ASTM IP 5C 6C 6 IC
IC 2C 63C
6.1.2.1 Since separation of liquid column thermometers occasionally occurs and may escape detection, the ice point of the thermometers shall be checked prior to the test and used only if they are accurate within + I*C (see Test Method E 77). 993
~
D 5853
THERMOME 1 ER
44,2
-
45.8
IO.
30 - 32.4 IO 322 - 3 4 8 (313
COR~:
JACKET 25 MAX. • ~
COOLANTLEVEL
TEST JAR FILL LEVEL" GASKET
COOt_I~
BATH
l,_.,.I t
-
I I_.~__
t
OISK NOTE--All dimensions are stated in millimetres. FIG. 1
Apparatus for Pour Point Test
6.1.3 Cork, to fit the test jar, center bored for the test thermometer. 6.1.4 Jacket, watertight, cylindrical, metal, fiat bottomed, 115 + 3 m m depth, with inside diameter of 44.2 to 45.8 mm. It shall be supported in a vertical position in the cooling bath (6.1.7) so that no more than 25 mm projects out of the cooling medium. The jacket shall be capable of being cleaned. 6.1.5 Disk, cork or felt, 6 mm thick to fit loosely inside the jacket. 6.1.6 Gasket, to fit snugly around the outside of the test jar and loosely inside the jacket. The gasket shall be made of rubber, leather, or other material that is sufficiently elastic to cling to the test jar and hard enough to hold its shape. Its purpose is to prevent the test jar from touching the jacket. 6.1.7 Cooling Bath or Baths, of a type suitable for obtaining the required temperatures. The size and shape of the bath are options, but a support to hold the jacket firmly in a vertical position is essential. The bath temperature shall be monitored by means of the appropriate thermometer (6.1.2) or any other temperature measuring device capable of measuring and displaying the designated temperature with the required precision and accuracy. The required bath temperatures shall either be maintained by refrigeration or by suitable freezing mixtures (Note 1) and shall maintain the designated temperatures to within +_.1.5"C.
For Temperatures Down To 9"C -12"C -27"C -57"C
Ice and water Crushed ice and sodium chloride crystals Crushed ice and calcium chloride crystals Acetone or petroleum naphtha (see Section 7) chilled in a covered metal beaker with an ice-salt mixture to -12"C and then with enough solid carbon dioxide to give the desired temperature. 6.2 Water Bath--The size and shape of the bath are optional, but a support to hold the test jar immersed in the bath to above the sample height in the test jar and in a firm vertical position is required. The required bath temperature may be maintained by any suitable means, provided the temperature can be monitored and controlled to the designated temperature (+ I*C (9.1.4; 9.2.4)). 6.3 Pressure Vessel,~ constructed of stainless steel according to the dimensions given in Fig. 2, and capable of withstanding a test pressure of 700 kPa. Alternative designs for the pressure vessel cap and synthetic rubber gasket may be used provided that the internal dimensions of the pressure vessel are the same as those shown in Fig. 2. 6.4 Timing Device, capable of measuring up to 30 s with a resolution of at least 0.1 s and an accuracy of +0.2 s or better. 6 The results of the cooperative test program from which these values have been derived are filed at ASTM Headquarters. Request RR:D02-1371.
NOTE l--The cooling mixtures commonly used are as follows:
994
~
D 5853
Dimensions in miilimetres
ling eye C'q 2 wide groove for pressure relief ignu rleo cap - 12 threads per in NF thread or equivalent
,Synthetic rubber " 0 " ring free from free sulphur
Chamfer inside cap to protect " 0 " ring when clos/ng bomb
tube o q3
Material: sta,nless steel Welded construction Maximum test pressure, gauge 700 kPa [7 bar)
FIG. 2
Pressure Vessel
7. Reagents and Materials
NOTE 4: Warning--Flammable. Vapor harmful.
7.1 The following solvents of technical grade are appropriate for low-temperature bath media.
7.1.4 Petroleum Naphtha. NOTE 5: Warning--Combustible. Vapor harmful. NOTE 6--Typical petroleum naptha used for cleaning purposes are VM and P napthas.
7.1.1 Acetone. NOTE 2: Warning--Extremely flammable. 7.1.2 Alcohol, Ethanol
7.2 Toluene, technical grade.
NOTE 3: WarningwFlammable.
NOTE 7: Warning--Flammable. Vapor harmful.
7.1.3 Alcohol, Methanol.
7.3 Solid Carbon Dioxide. 995
~
D 5853
NOTE 8: WarningmExtremely cold (-78.5"C). 8. Sampling, Test Samples, and Test Specimens
NoTE 9--Sampling is defined as all steps required to obtain a portion of the contents of any pipe, tank, or other system and to place the sample into the laboratory test container.
8.1 Laboratory Sample--It is essential that the sample received by the laboratory is representative of the batch or lot of crude oil from which it was taken. Practices D 4057 and D 4177 provide guidance for obtaining such representative samples. 8.2 Preparation of Test SamplesmThe pour point of crude oils is very sensitive to trace amounts of high melting waxes. Exercise meticulous care to ensure such waxes, if present, are either completely melted or, if volatility constraints prevent heating to complete melting, homogeneously suspended in the sample (Appendix X l). Inspect the walls of the original container to ensure that no high melting point material is left sticking to the wall. NOTE 10--1t is not possible to define universal mandatory rules for the preparation of crude oil test samples. Guidelines for sample handling for the most common situations are given in Appendix X I. 9. Procedure
9.1 Procedure A for Maximum (Upper) Pour Point." 9.1.1 Pour the test sample into the test jar to the level mark. If necessary, reheat the test sample to a temperature at least 20"C above the expected pour point (8.2 and Appendix X 1) but not higher than a temperature of 60"C (see Note 11). NOTE 11: WarningmThe vapor pressure of crude oils at temperatures higher than 60"C will usually exceed 100 kPa. Under these circumstances the sample container may rupture. Opening of the container may induce foaming with resultant loss of sample and possible injury to personnel. 9.1.2 Immediately close the test jar with the cork carrying the high cloud and pour thermometer, or, if the expected pour point is above 36"C, the melting point thermometer. Adjust the position of the cork and thermometer so the cork fits tightly, the thermometer and the jar are coaxial, and the thermometer bulb is immersed to a depth that places the beginning of the capillary 3 m m below the surface of the test specimen. 9.1.3 Keep the test jar with the test specimen at room temperature (between 18 and 24"C) for at least 24 h. NOTE 12--The pour point of a crude oil is dependent on the state of crystallization of the wax in the test specimen. In crude oils, achieving equilibrium between crystallized wax and dissolved wax is a rather slow process. However, experience has shown that in a majority ofcases, such an equilibrium is reached within 24 h. 9.1.4 If the expected pour point is greater than 36"C, heat the sample to 9"C above the expected pour point. If the expected pour point is less than 36"C, heat the sample to a temperature of 45 _+ I*C. Maintain the water bath (6.2) to heat the sample at 48 + I*C or at a temperature 12"C higher than the expected pour point, whichever is higher. 9.1.4.1 As soon as the test specimen has reached the required temperature, remove the cork carrying the thermometer and stir the test specimen gently with a spatula or similar device. Put the cork carrying the thermometer back in place (see 9.1.2). 9.1.5 Ensure that the disk, gasket, and the inside of the
jacket are clean and dry. Place the disk in the bottom of the jacket. Place the disk and jacket in the cooling medium a m i n i m u m of 10 min before the test jar is inserted. The use of a jacket cover, while the empty jacket is cooling, is permitted. Remove the test jar from the water bath and dry with a tissue. Place the gasket around the test jar, 25 m m from the bottom. Insert the test jar into the jacket in the first bath maintained at 21"C and commence observations for pour point. Never place a test jar directly into the cooling medium. 9.1.6 Exercise care not to disturb the mass of test specimen nor permit the thermometer to shift in the test specimen; any disturbance of the spongy network of wax crystals will lead to a lower pour point and erroneous results (Note 12). NOTE 13--With dark colored materials, such as crude oils, it is impractical to observe, in the test jar, the onset of crystallization and network formation in the test specimen. Hence, it is presumed that network formation will begin at the very early stages of the cooling sequence. 9.1.7 Pour points are expressed in temperatures which are positive or negative multiples of 3"C. Begin to examine the appearance of the test specimen when the temperature of the test specimen is 9"C above the expected pour point (estimated as a multiple of 3"C). At each test thermometer reading which is a multiple of 3"C below the starting temperature, remove the test jar from the jacket. When necessary, remove moisture that limits visibility of the test specimen by wiping the surface of the test jar with a clean cloth moistened in alcohol at approximately the temperature of the test specimen in the jar. Then tilt the jar just enough to ascertain whether there is movement of the test specimen in the jar. When movement is observed, immediately return the test jar into the jacket. The complete operation of removal and replacement shall require not more than 3 s. 9.1.7.1 If the test specimen has not ceased to flow when its temperature has reached 30"C, transfer the test jar to the next lower temperature bath per the following schedule: (a) If the test specimen is at +30"C, move to 0*C bath; (b) If the test specimen is at +9"C, move to - 1 8 " C bath; (c) If the test specimen is at -9"C, move to -33"C bath; and (d) If the test specimen is at -24"C, move to - 5 1 " C bath. 9.1.7.2 As soon as the test specimen in the jar does not flow when tilted, hold the jar in a horizontal position for 5 s, as shown by an accurate timing device (6.4) and observe carefully. If the test specimen shows any movement, replace the test jar immediately in the jacket and repeat a test for flow at the next temperature, 3"C lower. 9.1.8 Continue in this manner until a point is reached at which the test specimen shows no movement when the test jar is held in a horizontal position for 5 s. Record the observed reading of the test temperature. 9.1.8.1 If the test specimen has reached -36"C and still shows movement, discontinue the test. NOTE 14--To determine compliance with existing specifications having pour point limits at temperatures not divisible by 3"C, it is acceptable practice to conduct the pour point measurement according to the following schedule. Begin to examine the appearance of the test specimen when the temperature of the test specimen is 9"C above the specification pour point. Continue observations at YC intervals as described in 9.1.6 and 9.1.7 until the specification temperature is 996
~) D 5853 report as Maximum Pour Point, ASTM D 5853, Procedure A, or Minimum Pour Point, ASTM D 5853, Procedure B, if the procedure in 9.2 has been followed. 10.2 If the test was discontinued (9.1.8.1), report the pour point as - 100 kPa). As a rule of thumb, the vapor pressure doubles for every 20"C increase in temperature. X 1.3 flomogenization of Samples." XI.3.1 The proper means and effectiveness of mixing in order to achieve homogeneity depend, in addition to the physical properties (for example, viscosity) of the crude oil, on the capacity and shape of the container in which the crude oil arrives at the laboratory. It is virtually impossible to cater to every possibility and achieve optimum results under all circumstances. Guidelines are provided which in actual practice have proven to achieve the best possible results for the most common situations. X1.3.2 Drums, 15 to 200 L: X 1.3.2.1 The most effective way of achieving homogenization is mixing the contents of the drum on a roller bank in a hot room kept at a temperature between 40 and 60"C for 48 h (XI.2.3). Alternatively, keep the drum at a temperature of 20"C above the expected pour point for 48 h (XI.2.3) and roll the drum for at least 15 min before taking a sample. If heating of the drum is not feasible, the only alternative is
XI.3.3 Tins, I to 15 L: X1.3.3.1 Store the container at a temperature 20"C above the expected pour point (Xl.2.1) preferably in a water bath kept at the appropriate temperature. Alternatively, store the container in an explosion-proof oven, bearing in mind that local surface temperatures might be much higher than the oven temperature reading indicates. The time required to dissolve the wax will depend on the type of wax and the size of the container. For a 1 L tin, 2 h has been found to be adequate. For larger tins, longer times will be required. Although it is strongly recommended that the containers be closed when heated, it is advised that after approximately 30 min, the excess pressure is slowly released before continuing the heating. (WARNING: Note X 1.2) Mixing can be accomplished by a mechanical shaker or by vigorous manual shaking. Although the use of (high speed) mixers or similar devices might be effective, it will require that the container be open for some time, during which the escape of light ends can be excessive, and hence, this procedure is not recommended. NOTE X I.3: Warning--During this operation significantamounts of highly flammable vapors might escape. Vent in a safe area. XI.3.4 Bottles: XI.3.4.1 Follow as described in XI.3.3. Exercise special care when heating bottles that are closed with a cork or rubber stopper. The pressure build-up due to the heating will inevitably blow out the stopper. Take proper measures to safeguard against such an event (Notes X1.1 and X1.2). X 1.3.5 Plastic Containers: XI.3.5.1 The use of plastic containers for crude oil samples is strongly discouraged for a number of reasons (XI.I.7). If such a container is offered to the laboratory, however, the only way to handle these containers is by heating to a temperature 20"C above the expected pour point (X 1.2.1 and X 1.2.3) in a water bath kept at the appropriate temperature. The water bath prevents localized high temperatures in the container, which can create weak sections increasing the possibility of rupture. In any case, rupture of these containers due to pressure build-up is a distinct possibility and adequate measures must be taken to ensure safety (Note XI.2). X 1.3.6 Sample Receivers (Practice D 4177): XI.3.6.1 Follow the prescribed sample mixing and handling procedure as described in Practice D4177. It is recommended that a 1 L (tin) subsample be taken concurrently with subsampling for density and water and sediment, provided that the sample receiver has not been below the crude oil cloud point for more than 6 h. If the container has 998
~) D 5853 been kept at a temperature below the cloud point for more then 6 h, reheat the container to a temperature 20"C above
the expected pour point (XI.2.1 and XI.2.3) before mixing and subsampling.
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and ff not revised, either reepproved or withdrawn. Your comments a r e invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend, ff you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohockan, PA 19428.
999
(~1~ Designation: D 5863 - 95 Standard Test Methods for Determination of Nickel, Vanadium, Iron, and Sodium in Crude Oils and Residual Fuels by Flame Atomic Absorption Spectrometry 1 This standard is issued under the fixed designation D 5863; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (0 indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 These test methods cover the determination of nickel, vanadium, iron, and sodium in crude oils and residual fuels by flame atomic absorption spectrometry (AAS). Two different test methods are presented. 1.2 Test MethodA, Sections 7-12--Flame AAS is used to analyze a sample that is decomposed with acid for the determination of total Ni, V, and Fe. 1.3 Test Method B, Sections 13-17--Flame AAS is used to analyze a sample diluted with an organic solvent for the determination of Ni, V, and Na. This test method uses oil-soluble metals for calibration to determine dissolved metals and does not purport to quantitatively determine nor detect insoluble particulates. 1.4 The concentration ranges covered by these test methods are determined by the sensitivity of the instruments, the amount of sample taken for analysis, and the dilution volume. A specific statement is given in Note 3. 1.5 For each element, each test method has its own unique precision. The user can select the appropriate test method based on the precision required for the specific analysis. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific warning statements are given in Notes 1, 2, 5 and 6. 1.7 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
E 288 Specification for Laboratory Glass Volumetric Flasks 5 E 969 Specification for Volumetric (Transfer) Pipets 5
3. Summary of Test Methods 3.1 Test Method A - - O n e to twenty grams of sample are weighed into a beaker and decomposed with concentrated sulfuric acid by heating to dryness. The residual carbon is burned off by heating at 525"C in a muffle furnace. The inorganic residue is digested in dilute nitric acid, evaporated to incipient dryness, dissolved in dilute nitric and made up to volume with dilute nitric acid. Interference suppressant is added to the dilute nitric acid solution. The solution is nebulized into the flame of an atomic absorption spectrometer. A nitrous oxide/acetylene flame is used for vanadium and an air/acetylene flame is used for nickel and iron. The instrument is calibrated with matrix-matched standard solutions. The measured absorption intensities are related to concentrations by the appropriate use of calibration data. 3.2 Test Method B--Sample is diluted with an organic solvent to give a test solution containing either 5 % (m/m) or 20 % (m/m) sample. The recommended sample concentration is dependent on the concentrations of the analytes in the sample. For the determination of vanadium, interference suppressant is added to the test solution. The test solution is nebulized into the flame of an atomic absorption spectrometer. A nitrous oxide/acetylene flame is used for vanadium and an air/acetylene flame is used for nickel and sodium. The measured absorption intensities are related to concentrations by the appropriate use of calibration data. 4. Significance and Use 4.1 When fuels are combusted, metals present in the fuels can form low melting compounds that are corrosive to metal parts. Metals present at trace levels in petroleum can deactivate catalysts during processing. These test methods provide a means of quantitatively determining the concentrations of vanadium, nickel, iron, and sodium. Thus, these test methods can be used to aid in determining the quality and value of the crude oil and residual oil.
2. Referenced Documents 2.1 A S T M Standards: D 1193 Specification for Reagent Water 2 D 1548 Test Method for Vanadium in Heavy Fuel Oil 3 D4057 Practice for Manual Sampling of Petroleum and Petroleum Products 4 D 4177 Practice for Automatic Sampling of Petroleum and Petroleum Products 4 J These test methods are under the jurisdiction of ASTM Committee I)-2 on Petroleum Products and Lubricants and are the direct responsibility of Subcommittee D02.03.0B on Elemental Analysis. Current edition approved Dec. 10, 1995. Published February 1996. 2 Annual Book of ASTM Standards, Vol 11.01. 3 Annual Book of ASTM Standards, Vol 05.01. 4 Annual Book of ASTM Standards, Vol 05.02.
5. Purity of Reagents 5.1 Reagent grade chemicals shall be used for all tests. Unless otherwise indicated, it is intended that all reagents conform to the specifications of the Committee on Analyt-
1000
5 Annual Book of ASTM Standards, Vol 14.02.
o sss3 ical Reagents of the American Chemical Society where such specifications are available. 6 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination. 5.2 When determining metals at concentrations less than 1 mg/kg, use ultra-pure grade reagents. 5.3 Purity of Water--Unless otherwise indicated, reference to water shall be understood to mean reagent water conforming to Type II of Specification D 1193.
- - - I n f r a r e d Lamp
Vycor Vessel
6. Sampling and Sample Handling 6.1 The objective of sampling is to obtain a sample for testing purposes that is representative of the entire quantity. Only representative samples obtained as specified in Practices D 4057 and D 4177 shall be used. Do not fill the sample container more than two-thirds full 6.2 Prior to weighing, stir the sample and then shake the sample in its container. If the sample does not readily flow at room temperature, heat the sample to a sufficiently high and safe temperature to ensure adequate fluidity.
i
.~, ~
Air Bath
..._.. ~
Sample
~
Hot Plate
i
FIG. 1
TEST METHOD A--FLAME ATOMIC ABSORPTION AFTER ACID DECOMPOSITION OF THE SAMPLE
Decomposition Apparatus
7. Apparatus 7.1 Atomic Absorption Spectrometer, complete instrument with hollow cathode lamps and burners with gas supplies to support air-acetylene and nitrous oxide-acetylene flames (Warningmsee Note 1). NOTE 1: Warning--Hazardous. Potentially toxic and explosive. Refer to the manufacturer's instrument manual for associated safety hazards.
7.2 Sample Decomposition Apparatus (optional)--This apparatus is described in Fig. 1. It consists of a Vycor or Pyrex 400-mL beaker for the test solution, an air bath (Fig. 2) that rests on a hot plate and a 250 W infrared lamp supported 2.5 cm above the air bath. A variable transformer controls the voltage applied to the lamp. 7.3 Glassware--Vycor or Pyrex 400-mL beakers, volumetric flasks of various capacities and pipettes of various capacities. When determining concentrations below 1 rag/ kg, all glassware must be thoroughly cleaned (or soaked overnight) with 5 % HNO3 and rinsed five times with water. 7.4 Electric Muffle Furnace, capable of maintaining 525 + 25"C and sufficiently large to accommodate 400-mL beakers. The capability of an oxygen bleed is advantageous and optional. 7.5 Steam Bath. 7.6 Temperature Controlled Hot Plate, (optional). 7.7 Drying Oven, (optional), explosion-proof, if used to heat crude oils to obtain fluidity.
8. Reagents 8.1 Aqueous Standard Solutionsmlndividual
1
II
6 " E"
;
a ±"--,,-t
7 "
3T
j_
.%
5"
~1
1__%1 2 --
NOTE--All parts 16 gage (1.5 ram, 0,060 in.) aluminum. All dimensions are in
inches.
aqueous
Metric Equivalents
6 Reagent Chemicals, American Chemwal Soctety Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockvtlle, MD.
1001
in.
mm
in.
mm
1 11/= 2 31/la
25.4 38.1 50.8 77.8
37/a 5 61/2
98.4 127 165.1
FIG. 2
Air Bath
(@) D 5 8 6 3 standards with 1000 mg/kg concentrations of vanadium, nickel, and iron, purchased or prepared in acid matrix to ensure stability. 8.2 Nitric Acid--Concentrated nitric acid, HNO 3 (Warning--see Note 2). NOTE 2: Warning--Poison, oxidizer. Causes severe burns. Harmful or fatal if swallowed or inhaled.
8.3 Nitric Acid 50 % (V/V)nCarefully add, with stirring, one volume of concentrated nitric acid to one volume of water. 8.4 Dilute Nitric Acid, 5 % (V/V)nCarefully add, with stirring, one volume of concentrated nitric acid to 19 volumes of water. 8.5 Sulfuric Acid--Concentrated sulfuric acid, H 2 S O 4 (Warning--see Note 2). 8.6 Aluminum Nitrate, AI(NO3) 3 9HOH. 8.7 Potassium Nitrate, KNO3.
9. Preparation of Standards 9.1 Multi-Element Standard--Using the aqueous standard solutions, prepare a multi-element standard containing 100 mg/kg each of vanadium, nickel, and iron. Standards should be prepared to ensure accuracy and stability and should be stored in clean containers to safeguard against physical degradation. 9.2 Working Standards--Prepare at least two working standards to cover the concentration ranges specified in Table 1. For vanadium, add the specified interference suppressant. Each working standard must contain 5 % (V/V) nitric acid. Standards should be prepared to ensure accuracy and stability and should be stored in clean containers to safeguard against physical degradation. 9.3 Standard Blank, the standard blank contains 5 % (V/V) nitric acid and any interference suppressant specified in Table 1. 9.4 Check Standard--Prepare a calibration check standard in the same way as the working standards and at analyte concentrations that are typical of the specimens being analyzed. 10. Preparation of Test Solutions 10.1 Into a beaker, weigh an amount of sample estimated to contain between 0.0025 and 0.12 mg of each metal to be determined. A typical mass is 10 g. Add 0.5 mL of H2SO 4 for each gram of sample. NOTE 3--1f it is desired to extend the lower concentration limits of
the test method, it is recommended that the decomposition be done in 10-gincrements up to a maximum of 100 g. It is not necessaryto destroy all the organic matter each time before adding additional amounts ofthe sample and acid. When it is desired to determine higher concentrations, reduce the sample size accordingly. TABLE 1 AAS Conditions for the Determination of Vanadium, Nickel, and Iron Following Acid Sample Decomposition Element Vanadium
Wavelength, Concentration Interference nm Range, ltg/mL Suppressant 318.4
0.5-20
250 gg/mL AI, AI(NO3)a in
Flame N20-C=H=
5 • (v/v)
Nickel Iron
232.0 248.3
0.5-20 3.0-10
HNO3 None None
10.2 At the same time prepare reagent blanks using the same amount of sulfuric acid as used for sample decomposition. Reagent blanks should be carried through the same procedure as the samples. NOTE 4: Caution--Reagent blanks are critical when determining concentrations below 1 mg/kg. To simplify the analysis, use the same volume of acid and the same dilutions as used for the samples. For example, if 20 g of sample is being decomposed, use l0 mL of sulfuric acid for the reagent blank.
10.3 The use of the air bath apparatus (Fig. 2) is optional. Place the beaker in the air bath, which is located in the hood. The hot plate is off at this time. Heat gently from the top with the infrared lamp (Fig. 1) while stirring the test solution with a glass rod. As decomposition proceeds (indicated by a frothing and foaming), control the heat of the infrared lamp to maintain steady evolution of fumes. Give constant attention to each sample mixture until all risk of spattering and foaming is past. Then, gradually increase the temperature of both the hot plate and lamp until the sample is reduced to a carbonaceous ash. 10.4 If the air bath apparatus is not used, heat the sample and acid on a temperature controlled hot plate. As described in 10.3, monitor the decomposition reaction and adjust the temperature of the hot plate accordingly. NOTE 5: Precaution--Hot fuming concentrated sulfuric acid is very corrosive and a strong oxidizing acid. The analyst should work in a well-ventilated hood and wear rubber gloves and a suitable face shield to protect against spattering acid.
10.5 Place the sample in the muffle furnace maintained at 525 + 25°C. Optionally, introduce a gentle stream of oxygen into the furnace to expedite oxidation. Continue to heat until the carbon is completely removed. 10.6 Dissolve the inorganic residue by washing down the wall of the beaker with about 10 mL of the 1+1 HNO 3. Digest on a steam bath for 15 to 30 rain. Transfer to a hot plate and gently evaporate to incipient dryness. 10.7 Wash down the wall of the beaker with about 10 mL of dilute nitric acid (5 % V/V). Digest on the steam bath until all salts are dissolved. Allow to cool. Transfer quantitatively to a volumetric flask of suitable volume and make up to volume with dilute nitric acid. This is the test solution. 10.8 Pipette aliquots of the test solution into two separate volumetric flasks. Retain one flask for the determination of nickel and iron. To the other flask add aluminum interference suppressant for vanadium determination (refer to Table 1) and dilute up to mark with dilute nitric acid (5 % V/V). Similarly, prepare a reagent blank solution for vanadium analysis.
11. Preparation of Apparatus 11.1 Consult the manufacturer's instructions for the operation of the atomic absorption spectrometer. This test method assumes that good operating procedures are followed. Design differences between spectrometers make it impractical to exactly specify required instrument settings. 11.2 Set up the instrument to determine each analyte sequentially. 12. Calibration and Analysis 12.1 For each analyte in turn, perform the following operation.
Air-C=H= Air-C=H=
1002
~
D 5863
A A S Conditions for the Determination of Vanadium, Nickel, and Sodium Following Solvent Dilution of the Sample
TABLE 2 Element
Wavelength, nm
Concentration Range, mg/kg
Interference Suppressant
Flame
Vanadium Nickel Sodium
318.4 232.0 589.0
0.5-15 0.5-20 0.1-5
15 mg/kg AIA None None
N20-C2H = Air-C2H 2 Air-C2H =
TABLE 3
'* Prepared from an organometallic standard, mineral ell, and dilution solvent.
12.2 Nebulize the appropriate blank standard and zero the instrument. 12.3 Nebulize the working standards, determine the absorbance and construct a calibration curve of absorbance versus analyte concentration utilizing the instrument's concentration mode if available, otherwise plot these values. 12.4 Use the check standard to determine if the calibration for each analyte is accurate. If the results obtained on the check standard are not within +5 % of the expected concentration for each analyte, take corrective action and repeat the calibration. 12.5 Nebulize the test solutions and measure and record the absorbance. If appropriate, blank correct this absorbance by subtracting the reagent blank absorbance. 12.6 After measuring absorbances for a test solution, check the blank standard. If this does not read zero, check the system and then repeat steps 12.2 through 12.5. 12.7 Test solutions that give absorbances greater than that obtained with the most concentrated working standard must be diluted. The dilution must contain interference suppressant at the specified concentrations. TEST M E T l i O D B - - F L A M E ATOMIC ABSORPTION WITH AN ORGANIC SOLVENT TEST SOLUTION
13. Apparatus 13.1 Refer to Section 7.1. 13.2 Test Solution ContainersmGlass or plastic vials or bottles, with screw caps and a capacity of between 50 to 100 mL. Glass bottles of 100-mL capacity are satisfactory. 14. Reagents 14.1 Dilution Solvent--Mixed xylenes, o-xylene, tetralin and mixed paraffin-aromatic solvents are satisfactory (Warning--see Note 6). Solvent purity can affect analytical accuracy when the sample contains low concentrations (typically, a few mg/kg) of the analytes. NOTE 6: Warning--Combustible. Vapor harmful.
14.2 Mineral Oil--A high-purity oil such as U.S.P. white oil. 14.3 Organometallic Standards--Pre-prepared multi-element concentrates containing 100 mg/kg concentrations of each element are satisfactory. 7
15. Preparation of Standards and Test Solutions 15.1 Test Solution--Weigh a portion of well-mixed sample into a container and add solvent to achieve a sample concentration of either 5 % (m/m) or 20 % (m/m). Mix well. If the concentration of V, Ni, or Na in the sample exceeds 20 v Standards from the following source have been found satisfactory for this purpose: Conoco, Inc., Conostan Division, P.O. Box 1269, Ponca City, OK 74602.
1003
Element
Concentration Range, mg/kg
Vanad=um
50-500
Nickel
10-100
Iron Sodium
3-10 1-20
Repeatability Test Method A B A B A B
Repeatability, mg/kgA 1. lX °.r'° 0.13X °.92 0.20X o ss 0.005X T M 0.98 0.67X o.sa
A X = mean concentration, mg/kg.
mg/kg, the analysis for that element is performed on a test solution containing 5 % (m/m) sample. For concentrations less than 20 mg/kg, the analysis for that element is performed on a test solution that contains 20 % (m/m) sample. 15.2 Standards--If the test solution contains 5 % (m/m) sample, then the corresponding working standards and check standard must contain 5 % (m/m) oil. Similarly, if the test solution contains 20 % (m/m) sample, the standards must contain 20 % (m/m) oil. A consistent dilution factor is necessary so that all aspirated samples and standards will have the same viscosity. This is essential to obtain consistent uptake rates. 15.2.1 Working Standards--Prepare a blank (from mineral oil) and three additional working standards (from the organometallic standards) that cover the ranges of concentration specified in Table 2. 15.2.2 Check StandardmUsing the organometaUic standards, mineral oil, and dilution solvent, prepare a check standard to contain analyte concentrations approximately the same as expected in the test solutions.
16. Preparation of Apparatus 16.1 Refer to Section 11. 17. Calibration and Analysis 17.1 Refer to Section 12. 18. Calculation 18.1 For Test Method A, calculate the concentration of each analyte in the sample using the following equation: analyte concentration, rng/kg = (C x V x F)/W ( 1) where: C = concentration of the analyte in the test solution (corrected for the concentration determined in the reagent blank), txg/mL, V = volume of the test solution, mL, F = dilution factor, volume/volume or mass/mass, and W = sample mass, g. 18.2 For Test Method B, calculate the concentration of each analyte in the sample using the following equation. analyte concentration, mg/kg = C x F (2) where: C = concentration of the analyte in the test solution, mg/kg, and F = dilution factor, volume/volume or mass/mass. 19. Report 19.1 Report the following information: 19.1.1 Report concentrations in mg/kg to two significant figures.
(~) D 5863 TABLE 4
Element Vanadium
Calculated Repeatability (mg/kg) at Selected Concentrations (mg/kg) Test Method
Concentration 1
10
A
B Nickel
A
B Iron Sodium
A B
TABLE 5
0.12
0.89 0.13 0.98 1.2
Element
Concentration Range, mg/kg
Reproducibility Test Method
50
100
500
Vanadium
50-500
7.8 4.8 2.5 1.2
11.0 9.0 4.0 3.2
25.0 40.0
Nickel
10-100
A B A
3-10 1-20
A B
0.33Xo.=° 1.2Xo.°° 1.3X°-~ 0.06X1.= 1.45Xo.¢s 0.67X1.o
B Iron Sodium
Reproducibility, mg/kg A
" X = mean concentration, mg/kg.
20. Precision and Bias a
TABLE 6
20.1 Precision--The precision of this test method was determined by statistical analysis on interlaboratory test results. For Test Methods A and B, six cooperators participated in the interlaboratory study. Seven samples (four residual oils and three crude oils) comprised the test set. One residual oil was NIST SRM 1618. 6 One crude oil was NIST SRM 8505. 9 20.1.1 Repeatability---The difference between two test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test materials would, in the long run, in the normal and correct operation of the test method, exceed the values in Tables 3 and 4 only in one case in twenty. 20.1.2 Reproducibility--The difference between two single and independent results, obtained by different operators working in different laboratories on identical test matedais, would in the long run, in the normal and correct operation of the test method, exceed the values in Tables 5 and 6 only in one case in twenty. 20.2 Bias--Bias was evaluated from results obtained on a Request RR:D02-1351 for intedaboratory study data. Available from ASTM Headquarters. 9Available from the National Institute of Standards and Technology, Gaithersburg, MD 20899.
Calculated Reproducibility (mg/kg) at Selected
Concentrations (mg/kg) Element Vanadium Nickel Iron Sodium
Test Method A B A B A B
Concentration 1
0.59
10
4.4 0.95 4.1 6.9
50
100
500
11.0 27.0 10.0 6.6
21.0 48.0 15.0 15.0
89.0 170.0
two NIST samples. For Test Method A, the means of the reported values for V and Ni do not differ from the corresponding expected values by more than the repeatability of the test method. For Test Method B, the mean of the reported values for V does not differ from the corresponding expected value by more than the repeatability of the test method, and the mean of the reported values for Ni is higher than the expected value by an amount approximately equal to twice the repeatability of the test method. Standard reference materials for Fe and Na are not available, so bias was not determined for these elements.
21. Keywords 21.1 atomic absorption spectrometry; AAS; iron; nickel; sodium; vanadium
The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted In connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, ere entirely their own responsibility. This standard is subject to revision at any time by the responsible technical comm~ee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. Your comments will receive careful consideration at e meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received • fair hearing you should make your views known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohocken, PA 19428.
1004
~l[ ~ Designation: D 5917 - 96 Standard Test Method for Trace Impurities in Monocyclic Aromatic Hydrocarbons by Gas Chromatography and External Calibration 1 This standard is issued under the fixed designation D 5917; the number immediately following the designation indicates the year of original adoption or, in the ease of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (~) indicates an editorial change since the last revision or reapproval.
1. Scope 1.1 This test method covers the determination of the total nonaromatic hydrocarbons and trace monocyclic aromatic hydrocarbons in toluene and mixed xylenes by gas chromatography. The purity of toluene or mixed xylenes can also be calculated. Calibration of the gas chromatographic system is done by the external standard calibration technique. A similar test method, using the internal standard calibration technique, is Test Method D 2360. 1.2 Total aliphatic hydrocarbons containing 1 through 10 carbon atoms (methane through decanes) can be detected by this test method at concentrations ranging from 0.001 to 2.500 weight %. 1.2.1 A small amount of benzene in mixed xylenes may not be distinguished from the nonaromatics and the concentrations are determined as a composite (see 6.1). 1.3 Monocyclic aromatic hydrocarbon impurities containing 6 through 9 carbon atoms (benzene through C9 aromatics) can be detected by this test method at individual concentrations ranging from 0.001 to 1.000 weight %. 1.4 The following applies to all specified limits in this test method: for purposes of determining conformance with this test method, an observed value or a calculated value shall be rounded off "to the nearest unit" in the last fight-hand digit used in expressing the specification limit, in accordance with the rounding-off method of Practice E 29. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statement, see Section 9.
2. Referenced Documents 2.1 A S T M Standards: D 841 Specification for Nitration Grade Toluene2 D 2306 Test Method for C8 Hydrocarbon Analysis by Gas Chromatography2 D 2360 Test Method for Trace Impurities in Monocyclic Aromatic Hydrocarbons by Gas Chromatography2 D 3437 Practice for Sampling and Handling Liquid Cyclic Products2
D 4052 Test Method for Density and Relative Density of Liquids by Digital Density Meter3 D 4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards3 D4534 Test Method for Benzene Content of Cyclic Products by Gas Chromatography2 D 4790 Terminology of Aromatic Hydrocarbons and Related Chemicals: D 5211 Specification for Xylenes for p-Xylene Feedstock2 E 29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications 4 E 260 Practice for Packed Column Gas Chromatography4 E 355 Practice for Gas Chromatography Terms and Relationships4 E 691 Practice for Conducting an Interlaboratory Test Program to Determine the Precision of Test Methods4 E 1510 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs4 2.2 Other Document: OSHA Regulations, 29 CFR, paragraphs 1910.1000 and 1910.12005
3. Terminology 3.1 See Terminology D 4790 for definitions of terms used in this test method. 4. Summary of Test Method 4.1 A repeatable volume of the specimen to be analyzed is precisely injected into a gas chromatograph equipped with a flame ionization detector (FID). The peak area of each impurity is measured. Concentration of each impurity is determined from the linear calibration curve of peak area versus concentration. Purity by gas chromatography (GC) is calculated by subtracting the sum of the impurities found from 100.00. Results are reported in weight percent. 5. Significance and Use 5.1 Determining the type and amount of hydrocarbon impurities remaining from the manufacture of toluene and mixed xylenes used as chemical intermediates and solvents is often required. This test method is suitable for setting specifications and for use as an internal quality control tool where these products are produced or are used. Typical impurities are: alkanes containing 1 to 10 carbons atoms,
This test method is under the jurisdiction of ASTM Committee D-16 on Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of Subcommittee DI6.0E on Instrumental Analysis. Current edition approved Feb. 10, 1996. Published April 1996. 2 Annual Book of ASTM Standards, Vol 06.04.
1005
3 Annual Book of ASTM Standards, Vol 05.02. 4 Annual Book of ASTM Standards, Vol 14.02. 5 Available from Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402.
(@) D 5 9 1 7 benzene, toluene, ethylbenzene (EB), xylenes, and aromatic hydrocarbons containing nine carbon atoms. 5.1.1 Refer to Test Method D 2306 for determining the Cs aromatic hydrocarbon distribution in mixed xylenes. 5.2 Purity is commonly reported by subtracting the determined expected impurities from 100.00. However, a gas chromatographic analysis cannot determine absolute purity if unknown or undetected components are contained within the material being examined. 5.3 This test method is similar to Test Method D 2360, however, interlaboratory testing has indicated a bias may exist between the two methods. Therefore the user is cautioned that the two methods may not give comparable results. 6. Interferences 6.1 In some cases for mixed xylenes, it may be difficult to resolve benzene from the nonaromatic hydrocarbons. Therefore the concentrations are determined as a composite. In the event that the benzene concentration must be determined, an alternate method such as Test Method D 4534 must be selected to ensure an accurate assessment of the benzene concentration.
7. Apparatus
7.1 Gas Chromatograph--Any instrument having a flame ionization detector that can be operated at the conditions given in Table 1. The system should have sufficient sensitivity to obtain a minimum peak height response for 0.001 weight % impurity twice the height of the background noise. 7.2 Columns--A capillary column containing a stationary phase of cross linked polyethylene glycol has been found satisfactory. 7.3 Recorder--Electronic integration is recommended. 7.4 Injector--The specimen must be precisely and repeatably injected into the gas chromatograph. An automatic sample injection device is highly recommended although manual injection can be employed if the criteria in 12.7 can be satisfied. 7.5 Volumetric Flask, 100-mL capacity. 7.6 Syringe, 100 ~L. TABLE 1 Method Parameters Inlet Temperature, °C Column: Tubing Length, m Intemel diameter, mm Stationary phase Film thickness, p.m Column temperature program Initial temperature, °C Initial time, mm Programming rate, °C/min Final, =C Time 2, rain Carder gas Linear velocity, cm/s at 145°C Split ratio Sample size, ttL Detector: Temperature, °C Analysis time, min
Split 270 fused silica 60 0.32 crosslinked polyethylene glycol 0.25
8. Reagents
8.1 Purity of Reagent--Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society,6 where such specifications are available. 8.2 Carrier Gas--Chromatographic grade helium or hydrogen is recommended. 8.3 High Purity p-Xylene, 99.999 weight % or greater purity. 8.3.1 Most p-xylene is available commercially at a purity less than 99.9 % and can be purified by recrystallization. To prepare 1.9 L of high purity p-xylene, begin with approximately 3.8 L of material and cool in a flammable storage freezer at -10 + 5°C until approximately I/2 to 3/4 of the p-xylene has frozen. This should require about 5 h. Remove the sample and decant the liquid portion. The solid portion is the purified p-xylene. Allow the p-xylene to thaw and repeat the crystallization procedure on the remaining sample until the p-xylene is free of contamination as indicated by gas chromatography. 8.4 Pure compounds for calibration, shall include nnonane, benzene, toluene, ethylbenzene, o-xylene, and cumene. The purity of all reagents should be >99 weight %. If the purity is less than 99 %, the concentration and identification of impurities must be known so that the composition of the standard can be adjusted for the presence of the impurities. 9. Hazards 9.1 Consult current OSHA regulations, supplier's Material Safety Data Sheets, and local regulations for all materials used in this test method. 10. Sampling 10.1 Sample the material in accordance with Practice D 3437. 11. Preparation of Apparatus 11.1 Follow manufacturer's instructions for mounting and conditioning the column into the chromatograph and adjusting the instrument to the conditions described in Table 2, allowing sufficient time for the equipment to reach equilibrium. See Practices E260, E 355, and E 1510 for additional information on gas chromatography practices and terminology. 12. Calibration 12.1 Prepare a synthetic mixture of high purity p-xylene containing impurities at concentrations representative of those expected in the samples to be analyzed. The volume of each hydrocarbon impurity must be measured to the nearest 1 ~L and all liquid reference compounds must be brought to the same temperature before mixing. Refer to Table 3 for an
60 10 5 150 10 helium 20 100:1 1.0 flame ionization 300 30
6 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD.
1006
o s91z TABLE 2
Preparation
Compound
Density'~
p-Xylene (see 8.3.1) Benzene Toluene Ethylbanzene o-Xylene Cumane n-Nonane
0.857 0.874 0.862 0.863 0.876 0.857 0.714
Cumene will represent the aromatic hydrocarbons containing nine carbon atoms or greater (C9 aromatics). 12.l.l Prior to preparing the calibration standard, all reference compounds and any samples to be analyzed must be brought to the same temperature, preferably 25"C. 12.2 Using the exact volumes and densities in Table 2, calculate the weight % concentration for each impurity in the calibration blend as follows: C I = 100 D i V i / t V ~ D p ) (1)
Blend
of Calibration
Recommended ResultingConcentration Vol, p.L Volume 7, Weight 99.72 20.0 20.0 100.0 100.0 20.0 20.0
99.72 0.020 0.020 0.100 0.100 0.020 0.020
99.72 0.020 0.020 0.101 0.099 0.020 0.017
A Density at 25"C. Values obtained from "Physical Constants of Hydrocarbons C1 to Clo'; ASTM Publication DS 4A, 1971.
TABLE 3
Intermediate
Toluene
Precision
and
Reproducibility
Intermediate Precision
Nonaromatics (0.017) Ethylbenzene(0.017) p-Xylene (0.009) m-Xylane (0.013) o-Xylane (0.001) Toluene (99.94)
Reproducibility
0.0040 0.0014 0.0025 0.0013 0.0003 0.016
Mixed Xylanes
0.0083 0.0030 0.0027 0.0025 0.0005 0.021
Intermediate Precision
Nonaromatics (2.288) Toluene (0.675) Cumane (0.010) Xylenes (98.93)
where: D t = density of impurity i from Table 2, V; = volume of impurity i, mL, Dp - density ofp-xylene from Table 2, Vt = total volume of standard blend, mL, and C; = concentration of impurity i, weight %. 12.2.1 Alternatively, calibration standards may be used that have been gravimetrically prepared in accordance with Practice D 4307. 12.3 Inject the resulting solution from 12.1 into the chromatograph, collect and process the data. A typical chromatogram is illustrated in Fig. 1. 12.4 Determine the response factor for each impurity in the calibration mixture as follows: RFi = Ci/Al (2)
Reproducibility
0.1039 0.0244 0.0006 0.128
0.3688 0.1580 0.0020 0.369
where: RF# = response factor for impurity i, Az. = peak area of impurity i, and
example of a calibration blend, n-Nonane will represent the nonaromatic fraction and o-xylene the xylene fraction.
o-Xylene
\
p-Xylene Benzene
\
Toluene Ethylbenzene NonArcmatlca
i
....... \I --
1
0.0
!
I
1
[
2.0
I
I
!
I
4.0
I
'
I
'
6.0
'
'
'
I
'
'
'
8.0
'
[ ' iO.O
'
'
I
i2.0
'
'
'
'
I
t4.0
~4INUTES FIG. 1
Typical Chromatogram
1007
of Calibration
Standard
'
'
'
'
I
i5.0
'
'
'
'
I
i9.0
'
'
'
'
I
~.0.0
~
D 5917
C; = concentration of impurity i, as calculated in 12.2, weight %. 12.5 Analyze the calibration solution(s) a minimum of three times and calculate an average RF. 12.6 Determine the sample standard deviation for R F of each impurity using a scientific calculator or spreadsheet program. Determine the coefficient of variation for each R F as follows: CV i = 100 SDi/Avg i
tent with those made on the calibration blend. The nonaromatic fraction includes all peaks up to toluene (except for the peak assigned as benzene). Sum together all the nonaromatic peaks and report as a total area. The C9 aromatics fraction includes cumene and all peaks emerging after o-xylene. Sum together all the C9 aromatic peaks and report as a total area. 13.4 Figure 2 illustrates the analysis of Specification D 841, Toluene. Figure 3 illustrates the analysis of Specification D 5211, Mixed Xylenes.
(3)
where: CV, = coefficient of variation for RFi, SDi = standard deviation for RFi, and Avg i = average RF of impurity i.
14. Calculations 14.1 Calculate the weight percent concentration of the total nonaromatics and each impurity as follows. Use the response factor determined for n-nonane for all nonaromatic components, the factor for o-xylene for all xylenes, and the factor for cumene for all aromatic hydrocarbons containing nine or more carbon atoms as follows: C, ffi A,RFiDe/Ds (4) where: C, = concentration of impurity i, weight %, A/ = peak area of impurity i, RF, --- response factor of impurity i, from 12.4, D c = density of calibration solution (p-xylene), from Table 2, and D s ----density of sample, from Table 2 or Test Method D 4052. 14.2 Calculate the weight percent purity of the sample as follows:
12.7 The coefficient of variation for the response factor of any impurity, as calculated from a minimum of three successive analyses of the standard, shall not exceed 10 %. 13. Procedure 13.1 Bring the sample and calibration mixtures to identical temperatures, preferably 25"C. Make sure that the temperature of the sample is consistent with that of the calibration standard prepared in Section 12. 13.2 Depending upon the actual chromatograph's operating conditions, inject an appropriate amount of sample into the instrument. The injection amount shall be identical to the amount used in 12.3 and must be consistent with those conditions used to meet the criteria in 12.7. 13.3 Measure the area of all peaks except the major component(s). Measurements on the sample must be consis-
Toluene
Ethylbenzene ~Xylene
l
NonAromatics
.... I
0.0
!
I-~
I
2.0
I
I
,
4.0
6.0
8.0
o-Xylene ,
~,,,
, ~--{--r~-~--T--T--I--T=~--l--
t0.0
12.0
I
,
' ' ~ I J ' T r-]--r--r-r-T
i4.0
MINUTES FIG. 2
TypicalChromat~ramofSpecificationD841, Toluene
1008
16.0
t8.0
] 20.0
(~ D 5917
p-~l~e m-~l~e
Ethylbenzene
o-X ' l e n e
/
Toluene
NonAromatics
C9 ~omatics --
I
0.0
I
I
I
I
2.0
'
'
'
I 4.0
'
'
r
l
'
6.0
"
i
,
,
,
t
,
8.0
I
,-1"-',
t0.0
I
'
'
12.0
F
,
I
, M
t4.0
'
I
16.0
'
'
'
'
l
18.0
'
'
' I 20.0
MINUTES FIG. 3
Typical C h r o m a t o g r a m of Specification D 5211, X y l e n e s
purity, weight % = 100.00 - Ct (5) where: C~ = total concentration of all impurities, weight %. 15. Report 15.1 Report individual impurities, total nonaromatics, and total C9 aromatics, to the nearest 0.001%. 15.2 For concentrations of impurities less than 0.001%, report as