Methods for the Determination of Metals in Environmental Samples

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METHODS FOR THE DETERMINATION OF METALS AND INORGANIC CHEMICALS IN ENVIRONMENTAL SAMPLES

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METHODS FOR THE

DETERMINATION OF METALS AND INORGANIC CHEMICALS IN ENVIRONMENTAL SAMPLES

Environmental Monitoring Systems Laboratory Environmental Protection Agency Cincinnati, Ohio

NOY ES PUBLICATIONS Westwood, New Jersey, U.S.A.

Copyright 0 1996 by Noyes Publications No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system without permission in writing from the Publisher. Library of Congress Catalog Card Number: 96-12588 ISBN. 0-8155-1398-4 Printed in the United States Published in the United States of America by Noyes Publications 369 Faimiew Avenue Westwood, New Jersey 07675 10 9 8 7 6 5 4 3 2 1

Library of Congress Cataloging-in-Publication Data Methods for the determination of metals and inorganics in environmental samples / by Environmental Monitoring Systems Laboratory. p. cm. ISBN 0-8155-1398-4 1. Metals--Analysis--Laboratory manuals. 2. Inorganic compounds-Analysis--Labratory manuals. 3. Water--Analysis--Labratory manuals. 4. Sewage--Analysis--Laboratory manuals. I. Environmental Monitoring Systems Laboratory (Cincinnati, Ohio) TD196.M4M4897 1996 96-12588 628.1'61--dc20

CIP

FOREWORD Environmental measurements are required Po determine the quality of ambient waters and the character of waste effluents. The Environmental Monitoring Systems Laboratory-Cincinnati (EMSL-Cincinnati) conducts research to: Develop and evaluate analytical methods to identify and measure the concentration of chemical pollutants in marine and estuarine waters, drinking waters, surface waters, groundwaters, wastewaters, sediments, sludges, and so1id wastes . Investigate methods for the identification and measurement of viruses, bacteria and other microbiological organisms in aqueous samples and to determine the responses of aquatic organisms to water quality. Develop and operate a quality assurance program to support the achievement of data quality objectives in measurements of pollutants in marine and estuarine waters, drinking water, surface water, groundwater, wastewater, sediment and solid waste. Develop methods and models to detect and quantify responses in aquatic and terrestrial organisms exposed to environmental stressors and to correlate the exposure with effects on chemical and biological indicators. This supplement to the EMSL-Cincinnati publication, "Methods for the Determination of Metals in Environmental Samples" was prepared to revise and place in the Environmental Monitoring Management Council (EMMC) format certain spectrochemical methods used for metals analyses in regulatory compliance monitoring programs. Also, included in this supplement is a new method, Method 200.15 Determination of Metals and Trace Elements in Water by Ultrasonic Nebulization Inductively Coupled Plasma-Atomic Emission Spectrometry. This method is intended for analysis of ambient waters with possible limited use in regulatory compliance monitoring. We are pleased to provide this updated supplement to the manual and believe that it will be of considerable value to many public and private laboratories that wish to determine metals in environmental media for regulatory or other reasons. This EMSL-Cincinnati publication, "Methods for the Deterniination of Inorganic Substances in Environmental Samples," was prepared as the continuation of an initiative to gather together a compendium of standardized laboratory analytical methods for the determination V

vi

Foreword

of inorganic substances in water and wastewater. We are pleased to provide this manual and believe that it will be of considerable value to many public and private laboratories involved in inorganic analyses for regulatory or other reasons. Thomas A. Clark, Director

INTRODUCTION METHODS FOR THE DETERMINATION OF METALS IN ENVIRONMENTAL SAMPLES Six of the seven methods appearing in this supplement were included in the first publication of the manual "Determination of Metals in Environmental Samples," EPA 600 4-91/010, June, 1991. The one new method appearing in this supplement is Method 200.15, Determination of Metals and Trace Elements in Water by Ultrasonic Nebulization Inductively Coupled PlasmaAtomic Emission Spectrometry. Method 200.15 was developed to extend the analytical range of the ICP-AES technique to lower concentrations. Its usefulness for the analysis of drinking water is evident by the performance data included in the method. Unlike the 1991 manual (EPA 600 4-91/010) which contains 13 methods for a variety of sample matrices, this supplement is focused more on the analysis of water and wastes. Its purpose is for use in compliance monitoring of National Pollution Discharge Elinlination System (NPDES) effluents as required under the Clean Water Act and compliance monitoring of drinking water as required under the Safe Drinking Water Act. These methods are also useful for the analysis of ambient waters with the exclusion of marine water. The methods included in this supplement have been prepared in the format adopted by the Eiivironmental Monitoring Management Council (EMMC). In this format method sections are ordered in a specific manner and purpose with the addition of two new sections on pollution prevention and waste management. All methods have the same approach to analytical quality control in that initial demonstration of performance is required prior to method use, and assessing ongoing laboratory performance is mandatory. However, the required frequency of demonstration has been lessened and the acceptance control limits have been widened. Also, the required limits used in assessing recovery data from fortified matrices have been widened. Where available multi-laboratory data and regression equations Rave been included in the methods.

The multi-analyte methods (200.7, 200.8, 200.9, and 200.15) all utilize the same total recoverable sample digestion procedure that is described in Method 200.2 as a stand-alone procedure. This procedure also is applicable to flame atomic absorption determinations. Using a common sample preparation for all spectrochemical techniques is convenient and can reduce cost of analyses. vii

...

Introduction

VIII

Changes to previous versions of specific methods are as follows: 0

Cerium has been added to Method 200.7 for correction of potential spectral interferences

0

Titanium has been added as an analyte to Method 200.7 Mercury has been added to Method 200.8 for the analysis of drinking water with turbidity of (1 NTU

o

Zinc has been deleted from Method 200.9 because its determination by the graphite furnace techniques is impractical

0

Digestion of Method 245.1 mercury calibration standards is no longer required.

METHODS FOR THE DETERMINATION OF INORGANIC SUBSTANCES IN ENVIRONMENTAL SAMPLES The original version of this manual was issued in November 1969 by the Federal Water Pollution Control Administration as "FWPCA Methods for Chemical Analysis of Water and Wastes." With the creation of the United States Environmental Protection Agency (USEPA) came "Methods for Chemical Analysis of Water and Wastes 1971" Publication No. 160207/71. The second edition was issued in 1974 as EPA 625/6-74-003, and the third edition in 1979 as EPA 600/4/79-020. The current version, an updated second printing of the third edition, was revised and issued in March 1983. The methods contained in the I983 manual form the basis for most of the methodology approved for compliance monitoring of inorganic parameters specified under the Clean Water Act (NPDES) and contaminants regulated under the Safe Drinking Water Act. In 1991, a number of new and revised metals methods were incorporated into a new publication entitled, "Methods for the Determination of Metals in Environmental Samples." Concurrently, the decision was made to revise and update selected non-metal methods to be issued under the name "Methods for the Determination of Inorganic Substances in Environmental Samples." For both the metals and non-metals manuals, several important features were adopted: o

Consistent use of terminology, a feature especially helpful in the quality control sections where standardized terminology is not yet available. The terms were carefully selected to be meaningful without extensive definition, and therefore should be easy to understand and use. New sections are included with expanded useful coverage of safety, quality control, pollution prevention and waste management. All methods are presented in the new EPA standard Environmental Monitoring Management Council (EMMC) format.

Although a number of other methods included the 1983 edition of USEPA "Methods for Chemical Analysis of Water and Wastes," Standard Methods for the Examination of Water

Introduction

ix

and Wastewater, and American Society for Testing and Materials Annual Book of Standards (ASTM) are acceptable for compliance monitoring, the revised methods contained in this publication are considered to be the most useful in terms of future regulatory requirements. They represent a selection of air segmented automated, semi-automated, or amenable to automation methodology that provides the following advantages over their manual counterparts. 0

Higher sample throughput for faster analysis and improved precision.

0

Faster analysis allows more time to perform the updated quality control required to insure valid results.

0

Lower per analysis reagent consumption to reduce waste production and minimize disposal costs. The inclusion of multi-laboratory data generated from USEPA performance evaluation studies.

The following methods are included with specific features and improvements: 0

A revised version of TPA turbidity Method 180.1 that minimizes the direct use of hydrazine sulfate.

o

An updated version of EPA Method 300.0 for anions by ion chromatography.

0

A new stand alone semi-automated revision of EPA cyanide Method 335.2 that specifies the use of the downsized midi-distillation procedure.

0

A new semi-automated version of the EPA phenolics Method 420.2. The optional use of a non-mercury catalyst in EPA TKN Method 351.2.

0

All methods allow the optional use of reduced reagent and distillationdigestion volumes.

Most of the methods include the option of limited performance-based modifications or improvements. James W. O'Dell, John D. Pfaff, William L. Budde Chemistry Research Division

NOTICE To the best of our knowledge the information in this publication is accurate; however, the Publisher does not assume any responsibility or liability for the accuracy or completeness of, or consequences arising from, such information. This book is intended for informational purposes only. Mention of trade names or commercial products does not constitute endorsement or recommendation for use by the Publisher. Final determination of the suitability of any information or product fox use contemplated by any user, and the manner of that use, is the sole responsibility of the user. We recommend that anyone intending to rely on any recommendation of materials or procedures mentioned in this publication should satisfy himself as to such suitability, and that he can meet all applicable safety and health standards. X

CONTENTS AND SUBJECT INDEX PART I METHODS FOR THE DETERMINATION OF METALS IN ENVIRONMENTAL SAMPLES Determination of Acid-Soluble Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Sample Preparation Procedure for Spectrochemical Determination of . . . I2 Total Recoverable Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200.3 Sample Preparation Procedure for Spectrochemical Determination of Total Recoverable Elements in Biological Tissues . . . . . . . . . . . . . . . . 24 200.7 Determination of Metals and Trace Elements in Water and Wastes by Inductively Coupled Plasma-Atomic Emission Spectrometry . . . . . . . . . 31 200.8 Determination of Trace Elements in Waters and Wastes by Inductively Coupled Plasma-Mass Spectrometry . . . . . . . . . . . . . . . . . 88 200.9 Deterniination of Trace Elements by Stabilized Temperature Graphite . . 146 Furnace Atomic Absorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200.10 Determination of Trace Elements in Marine Waters by On-Line Chelation Preconcentration and Inductively Coupled Plasma. . 187 Mass Spectrometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200.11 Determination of Metals in Fish Tissue by Inductively Coupled Plasma-Atomic Emission Spectrometry . . . . . . . . . . . . . . . . . . . . . . 210 200.15 Determination of Metals and Trace Elements in Water by Ultrasonic Nebulization Inductively Coupled Plasma-Atomic Emission . . 243 Spectrometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218.6 Determination of Dissolved Hexavalent Chromium in Drinking Water, Groundwater, and Industrial Wastewater Effluents by Ion . . 290 Chromatography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245.1 Determination of Mercury in Water by Cold Vapor Atomic Absorption . . 305 Spectrometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245.3 Determination of Inorganic Mercury (11) and Selected Organomercurials in Drinking and Groundwater by High Performance Liquid Chromolography (HPLC) with Electrochemical Detection (ECD) . . . . . . . . . . 323 245.5 Detemiination of Mercury in Sediments by Cold Vapor Atomic . . 349 Absorption Spectrometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245.6 Deterniination of Mercury in Tissues by Cold Vapor Atomic Absorption . . 363 Spectrometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

200.1 200.2

Xi

xii

Contents and Subject Index

PART I1 METHODS FOR THE DETERMINATION OF INORGANIC SUBSTANCES IN ENVIRONMENTAL SAMPLES 180.1 300.0 335.4 350.1 351.2 353.2

Determination of Turbidity by Nephelometry . . . . . . . . . . . . . . . . . . . . . . Determination of Inorganic Anions by Ion Chromatography . . . . . . . . . . . Determination of Total Cyanide by Semi-Automated Colorimetry . . . . . . . . Determination of Ammonia Nitrogen by Semi-Automated Colorimetry . . . . . , . . . . . . . . . . . . . . . . . . . . . * . . . . ~. . , . . . . . . Determination of Total Kjeldahl Nitrogen by Semi-Automated Colorimetry . . . . . . . . . . . . . . . . . . . . ~.. . . . . . . . . . . ~. . . . . . . . Determination of Nitrate-Nitrite Nitrogen by Automated Colorimetry . . . . . . ~. . ~. . . . . . . . ~. . . . . . . . . . . . . , * . . . . . . Determination of Phosphorous by Semi-Automated Colorimetry . . . . . . . . . Determination of Sulfate by Automated Colorimetry . . . . . . . . . . . . . . . . . The Determination of Chemical Oxygen Demand by Semi-Automated Colorimetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Deterniination of Total Recoverable Phenolics by Semi-Automated Colorimetry . . . . . . . . . . ~. . . . . . . . . . . . . . . . . . . . . . . . . . . . ~

~

365.1 375.2 410.4 420.4

D

.

.

I

378 388 418 434 449

464 479 496

509 522

PART I METHODS FOR THE DETERMINATION OF METALS IN ENVIRONMENTAL SAMPLES

1

2

Methods for the Determination

METHOD 200.1 DETERMINATION OF ACID-SOLUBLE METALS

Theodore D. Martin and James W . O'Dell Inorganic Chemistry Branch Chemistry Research Division and Gerald D . McKee Office o f the Director

Revision 2.0 April 1991

ENVIRONMENTAL MONITORING SYSTEMS LABORATORY OFFICE OF RESEARCH AND DEVELOPMENT U.S. ENVIRONMENTAL PROTECTION AGENCY CINCINNATI, OHIO 45268

Metals

3

METHOD 200.1 DETERMINATION OF ACID-SOLUBLE METALS 1.

SCOPE AND APPLICATION

1.1

This method can be used to determine acid-soluble metals’ in ambient waters and aqueous wastes. Results from this method may be used to calculate or estimate the potential impact on aquatic life and water quality. It is applicable to the analysis of arsenic ( A s ) , cadmium (Cd), chromium (Cr), copper (Cu) , and lead (Pb) .

1.2 This method provides instructions for sample handling, preservation, and preparation prior to analysis using spectrochemical methods given in this manual. Specific references are listed in Sect. 1 1 . 3 of this method. 1 . 3 This method is designed to be a supplement to approved EPA

spectrophotometric and spectrochemical methods, however, it does not provide for oxidation state or organometallic speciation. For a summary and description of the analytical techniques employed, their estimated instrumental detection limits, definition of terms specific to each technique, types of interferences encountered, instrumental requirements, reagents and standards required for analysis, calibration, general instrumental operating procedures, instrumental qua1 ity control, data calculation and reporting, see appropriate parts of the methods referenced in Sect. 1 1 . 3 of this method. 2.

SUMMARY OF METHOD

2.1 This method describes procedural instruction for treating an aqueous sample for determination of acid-soluble metals prior to either atomic absorption or atomic emission spectrochemical analysis. The aqueous sample is acidified to a pH of 1.,75 f 0 . 1 and held for a period of at least 16 h before being filtered through a 0.45-1m membrane filter and appropriately processed for analysis. 3.

DEFINITIONS

3.1

4.

Acid-Soluble Metal: That portion of the metal concentration that will pass through a 0.45-pm membrane filter after the solution to be filtered has been adjusted to within a DH 1.75 f 0.1 and held for a period of 16 h .

INTERFERENCES

4.1

Contamination is of primary concern in determining acid-solub e metals. All sample containers, labware, filtering and sample processing apparatus should be washed as described in Sect. 8

4

5.

Methods for the Determination SAFETY 5.1

6.

7.

Ammonium h y d r o x i d e and n i t r i c a c i d a r e m o d e r a t e l y t o x i c and i r r i t a t i n g t o s k i n and mucus membranes. Use c o n c e n t r a t e d r e a g e n t s i n a hood and i f eye o r s k i n c o n t a c t occurs, f l u s h w i t h l a r g e volumes o f w a t e r . Always wear s a f e t y g l a s s e s o r a s h i e l d f o r eye p r o t e c t i o n when w o r k i n g w i t h t h e s e r e a g e n t s .

APPARATUS 6.1

pH M e t e r - l a b o r a t o r y o r f i e l d model: A wide v a r i e t y o f i n s t r u m e n t s a r e c o m m e r c i a l l y a v a i l a b l e w i t h v a r i o u s s p e c i f i c a t i o n s and o p t i o n a l equipment. The i n s t r u m e n t must be capable o f measuring pH t o 0 . 1 u n i t s and s h o u l d be a m e t e r equipped w i t h a c o m b i n a t i o n e l e c t r o d e .

6.2

F i l t e r f u n n e l and s u p p o r t : O n l y g l a s s o r p l a s t i c f i l t e r i n g apparatus s h o u l d be used. The s u p p o r t s h o u l d be c a p a b l e o f a c c e p t i n g b o t h t h e p r e f i l t e r and f i n e f i l t e r w h i l e m a i n t a i n i n g a no-leak s e a l between t h e f u n n e l and s u p p o r t . The Gelman model 4201 o r equivalent i s acceptable.

6.3

S u c t i o n f l a s k , 500-mL c a p a c i t y .

6.4

Membrane f i l t e r d i s c s : Because t h e sample s o l u t i o n t o be f i l t e r e d w i l l be o f l o w pH (1.75 k O . l ) , t h e f i l t e r media may be e i t h e r a p o l y v i n y l c h l o r i d e a c r y l i c copolymer o r mixed e s t e r s o f c e l l u l o s e m a t e r i a l . The f o l l o w i n g 47-mm membrane f i l t e r s o r e q u i v a l e n t a r e acceptable. 6.4.1

Fine p r e f i l t e r :

DM-800, 0.8-pm (Gelman No.64502)

6.4.2

Fine f i l t e r : DM-450, 0.45-pm (Gelman No. 64515) o r HAWP-047, 0.45 pm ( M i l l i p o r e No. HAWP 047 00)

6.5

Sample c o l l e c t i o n c o n t a i n e r s : C u b i t a i n e r , p o l y e t h y l e n e , 1 q u a r t (0.95L) c a p a c i t y o r e q u i v a l e n t .

6.6

Sample s t o r a g e b o t t l e s : Wide-mouth h i g h - d e n s i t y p o l y e t h y l e n e w i t h p o l y p r o p y l e n e screw cap c l o s u r e , 500-mL c a p a c i t y .

6.7

Glassware:

6.8

For t h e apparatus and equipment needed f o r t h e a n a l y t i c a l t e c h n i q u e employed, see t h e s p e c i f i c r e f e r e n c e s .

C l a s s A v o l u m e t r i c f l a s k s and p i p e t s o f v a r i o u s volumes.

REAGENTS AND STANDARDS 7.1

Deionized, d i s t i l l e d w a t e r : Prepare by p a s s i n g d i s t i l l e d w a t e r t h r o u g h a mixed bed o f c a t i o n and a n i o n exchange r e s i n s . Use d e i o n i z e d , d i s t i l l e d w a t e r f o r t h e p r e p a r a t i o n o f a l l r e a g e n t s and as d i l u t i o n o r r i n s e w a t e r . The p u r i t y o f t h i s w a t e r must be e q u i v a l e n t t o ASTM Type 11 r e a g e n t w a t e r o f S p e c i f i c a t i o n D 11933.

Metals 7.2

Nitric acid, conc. (sp.gr. 1 . 4 1 ) , ultra-high purity grade or equivalent. Redistilled acid is acceptable. 7.2.1

7.3

Nitric acid, ( l t l ) : Add 500 mL conc. HNO (Sect. 7 . 2 ) to 400 mL deionized, distilled water (Sect. j . 1 ) and dilute to 1 L.

Hydrochloric acid, conc. (sp. gr. 1 . 1 9 ) . 7.3.1

8.

5

Hydrochloric acid, ( l t l ) : Add 500 mL conc. HC1 (Sect. 7 . 3 ) to 400 mL deionized, distilled water (Sect. 7 . 1 ) and dilute to 1 L .

7.4

Ammonium Hydroxide, ( 1 t 9 ) : Dilute 10 mL conc. ammonium hydroxide, NH,OH (analytical reagent grade), to 100 mL with deionized, distilled water (Sect. 7 . 1 ) .

7.5

Buffer solutions: Two buffer solutions are required, one in the range of pH 2 and the other at pH 7 . These may be prepared or purchased as commercially available certified solutions. The use of purchased buffer solutions certified at a pH of 2 and 7 is recommended.

SAMPLE COLLECTION, PRESERVATION AND STORAGE

8.1

For the determination of acid-soluble metals, contamination and loss are of prime concern. Dust in the laboratory environment, impurities in reagents and improperly cleaned laboratory apparatus which the sample contacts are all potential sources of contamination. Sample containers can introduce either positive or negative errors in the measurement of metals by (a) contributing contaminants through leaching or surface desorption and/or (b) by depleting concentration through adsorption. Laboratory glassware, including the sample collection cubitainer and the polyethylene samp7e storage bottle, as well as the filtering apparatus should be thoroughly washed with detergent and tap water; thoroughly rinsed with ( l f l ) nitric acid, tap water, ( l t l ) hydrochloric acid, tap water and finally deionized distilled water in that order (See Notes 1 and 2 ) . To remove difficult organic deposits from glassware, a commercial product, NOCHROMIX, available from Godax Laboratories, 480 Canal Street, New York, New York 10013 may be used. This product should not be used on plastic containers or filtering apparatus.

NOTE 1:

If it can be documented through an active analytical quality control program using spiked samples, laboratory control standards and reagent blanks that certain steps in the cleaning procedure are not required, those steps may be eliminated from the procedure.

NOTE 2 :

6


8.2 At the time o f sample collection, the sample cubitainer is rinsed

with the sample solution and the rinse portion discarded. The cubitainer is then filled with approximately 800 mL o f sample, acidified with 2 mL of (ltl) nitric acid and mixed. For most ambient waters the acid addition will lower the pH to near 2, but not lower than 1.75. The cubitainer is sealed, placed in an ice chest at 4 " C , and returned to the laboratory. Note the date and time of preservation on the sample tag. 8.3 The sample should not be held more than 3 days at 4°C from the day of collection before processing is started. The filtrate is estimated to be stable for 30 days. 9.

CALIBRATION AND STANDARDIZATION

9.1 Calibration of pH meter - Because of the wide variety of pH meters and accessories, detailed operating procedures cannot be incorporated into this method. Each analyst must be acquainted with the operation of the system being used and familiar with all instrument functions. Special attention to care of the combination electrode is recommendedi See Method 150.1 given in EPA 600/4-79-020, March 1983 . 9.2 Each instrument/electrode system must be calibrated at a minimum of two points, one at or near pH 2, the other at pH 7. Calibrate according to manufacturer's instructions and measure the pH of each sample. Using deionized distilled water (Sect. 7.1), rinse the electrode system after each pH measurement. 10.

QUALITY CONTROL

10.1 The following quality assurance procedures represent 5% of the analyzed sample load for 20 samples. 10.2 To measure recovery and cross contamination between samples that may occur, 300 mL o f a laboratory control standard containing all six metals, each at a concentration above 1OX its determined method detection limit (MDL), is transferred to a cleaned cubitainer, adjusted to a pH range of 1.75 ? 0.1 and allowed to stand for a minimum of 16 h. At a selected point midway through the group of samples to be analyzed, the control standard is filtered. The analyzed values should be within the warning limits of f2 standard deviations of an established mean value as determined from seven prior replicate analyses. If an analyzed value was greater than +3 standard deviations from the mean, the analysis was out of control. 10.3 To determine the MDL of each metal, prepare seven aliquots of the sample matrix of concern, spike the aliquots with each metal to a concentration o f 3 to 5 times its estimated detection limit and follow the procedure - "Definition and Procegure for the Determination o f the Method Detection Limit.

Metals

11.

7

PROCEDURE

11.1 SAMPLE pH ADJUSTMLNT For the determination of acid-soluble metals, the pH o f the sample must be 1.75 f 0.1. Upon receiving the sample in the laboratory, check the sample tag for proper preservation and to see that the holding time has not been exceeded. Allow the sample to come to room temperature, calibrate the pH meter and measure the pH of the sample in the cubitainer. Using deionized distilled water (Sect. 7.1), rinse the electrode system after each pH measurement. Do not wipe the electrode. ~

11.1.1

If the sample pH is between 1.65 and 1.85, mix the sample and allow to stand at room temperature for a minimum of 16 h f o r required dissolution. At the end of the extraction period, measure the pH again to verify that the proper pH was maintained, and if so, filter according to paragraph If pH was not maintained, a new sample should be 11.2. requested and more care and time taken in the initial pH adjustment.

11.1.2

If the sample pH is above 1.85, add (ltl) nitric acid in a dropwise manner, mix the sample in the cubitainer by inverting and shaking and redetermine the pH. Continue adding small increments of the (1t1) nitric acid and mix until the sample is within the desired pH range. If the pH should go below 1.65, add (1t9) ammonium hydroxide (Sect. 7.3) in a dropwise manner until the sample is within the pHrange of 1.65 to 1.85. Once the pH of the sample is properly adjusted and thoroughly mixed, set the sample aside for a minimum of 16 h for the required dissolution to occur. At the end of the extraction period, measure the pH again to verify the proper pH was maintained, and if so, filter according to paragraph 11.2. If pH was not maintained, a new sample should be requested and more care and time taken in the initial pH adjustment .

11.1.3

If upon receipt the sample has a pH below 1.65, the sample should be discarded and the collection of a new sample requested. The sample collection team should be informed of the reason why the previous sample was rejected.

11.2 SAMPLE FILTRATION - For determination of acid-soluble metals, the pH-adjusted sample is filtered through a 0.45-pm membrane filter. To prevent clogging of the filter, the sample is first passed through a fine prefilter. 11.2.1

Before filtering any sample make certain that the filtering apparatus (Sects. 6.2 and 6.3), polyethylene storage bottles (Sect. 6.7) and other necessary glassware have been cleaned by the procedure described in Sect. 8.1

8

Methods for the Determination 11.2.2

I n s e r t t h e l - i l t e r s u p p o r t o f t h e f i l t e r i n g apparatus t h r o u g h t h e p r o p e r s i z e r u b b e r s t o p p e r and w r a p t h e s t o p p e r w i t h 1 i n . PTFE l a b o r a t o r y t a p e t o p r e v e n t c o n t a m i n a t i o n . Secure t h e f l a s k i n an u p r i g h t p o s i t i o n and p l a c e t h e s u p p o r t i n t h e neck of t h e s u c t i o n f l a s k . Connect t h e s u c t i o n f l a s k t o t h e vacuum 1 i n e .

11.2.3

P l a c e t h e membrane f i l t e r s ( S e c t . 6 . 4 ) on t h e f i l t e r s u p p o r t i n t h e f o l l o w i n g o r d e r : f i r s t t h e 0.45-pm f i n e f i l t e r and t h e n t h e 0.8-pm p r e f i l t e r . Assemble t h e f i l t e r f u n n e l t o t h e s u p p o r t as recommended by t h e m a n u f a c t u r e r .

11.2.4

Do n o t m i x t h e sample, b u t c a r e f u l l y d e c a n t a p p r o x i m a t e l y 50 mL o f sample f r o m t h e c u b i t a i n e r i n t o t h e f i l t e r i n g f u n n e l and a p p l y t h e vacuum. A f t e r f i l t r a t i o n , b r e a k t h e vacuum, remove t h e f i l t e r i n g apparatus, r i n s e t h e s u c t i o n f l a s k w i t h t h e f i l t r a t e and d i s c a r d .

11.2.5

Reassemble t h e f i l t e r i n g a p p a r a t u s and s u c t i o n f l a s k , r e a p p l y t h e vacuum and c a r e f u l l y decant a p p r o x i m a t e l y 250 o f a d d i t i o n a l sample i n t o t h e f i l t e r i n g apparatus.

mL

11.2.6

When f i l t r a t i o n i s complete, b r e a k t h e vacuum, t r a n s f e r t h e f i l t r a t e t o a l a b e l e d , cleaned, p o l y e t h y l e n e s t o r a g e b o t t l e ( S e c t . 6.7) and s t o r e u n t i l a l l analyses have been completed, n o t t o exceed 30 days. The r e m a i n i n g u n f i l t e r e d p o r t i o n o f t h e sample may be d i s c a r d e d .

11.2.7

B e f o r e f i l t e r i n g a d d i t i o n a l samples, d i s c a r d t h e f i l t e r s , r i n s e t h e s u c t i o n f l a s k and f i l t e r i n g apparatus w i t h c o p i o u s amounts o f d e i o n i z e d d i s t i l l e d w a t e r ( S e c t . 7.1), d i s c a r d t h e r i n s e w a t e r and d r a i n away any excess w a t e r .

11.2.8

Repeat t h e above p r o c e d u r e u n t i l a l l samples and q u a l i t y c o n t r o l a1 i q u o t s have been f i l t e r e d .

11.3 SAMPLE ANALYSES - The l e v e l o f m e t a l c o n c e n t r a t i o n w i l l d e t e r m i n e t h e a n a l y t i c a l method s e l e c t e d t o complete t h e a n a l y s i s . 11.3.1

I n d u c t i v e l y c o u p l e d plasma-atomic e m i s s i o n (ICP) s p e c t r o m e t r i c analyses - The a c i d - s o l u b l e m e t a l s As, Cd, C r , Cu and Pb can be analyzed by d i r e c t a s p i r a t i o n ICP s p e c t r o m e t r y u s i n g t h e p r o c e d u r e d e s c r i b e d i n Method 200.7 o f t h i s manual. To p r e p a r e t h e sample f o r analyses, p i p e t 2 mL ( l t l ) h y d r o c h l o r i c a c i d i n t o a 50-mL v o l u m e t r i c f l a s k and d i l u t e t o t h e mark w i t h sample f i l t r a t e . T h i s d i l u t i o n r e q u i r e s an a p p r o p r i a t e f a c t o r be a p p l i e d t o t h e f i n a l c a l c u l a t i o n s . I n t h e absence o f an e s t a b l i s h e d MDL (Sect. l O . Z . l ) , the f o l l o w i n g estimated instrumental d e t e c t i o n l i m i t f o r each element s h o u l d be c o n s i d e r e d t h e l i m i t o f analysis.

Metals

Element

Estimated D e t e c t i o n L i m i t mq/L

0.03 0.02 0.007 0.003 0.03

As Cd Cr cu Pb 11.3.2

9

D i r e c t a s p i r a t i o n flame atomic a b s o r p t i o n (FLAA) analyses - The a c i d - s o l u b l e metals Cd, C r , Cu and Pb can be analyzed by procedures g i v e n i n approved FLAA methods w i t h o u t r e q u i r i n g a d d i t i o n a l processing o f t h e f i l t r a t e b e fo re a n a l y s i s . L i s t e d below are t h e method numbers and estimated i n s tru m e n ta l d e t e c t i o n l i m i t s , which i n t h e absence o f an e s t a b l i s h e d MDL (Sect. 10.2.1), should be considered t h e FLAA l i m i t o f a n a l y s i s f o r d i r e c t a s p i r a t i o n . I n a d d i t i o n t o t h e i n d i v i d u a l methods, f o r t h e proper a n a l y s i s procedure, see p a r t s 9 . 1 o f Section 200.0: Atomic Absorption Methods g i v e n i n EPA 600/4-79-020, March 19832

.

Element Cd Cr

cu Pb

11.3.3

Method Number

Estimated D e t e c t i o n L i m i t , mq/L

213.1 218.1 220.1 239.1

0.005 0.05 0.02 0.1

S t a b i l i z e d Temperature Graphite Furnace Atomic Absorption (STGFAA) ANALYSES - For STGFAA a n a l y s i s o f t h e a c i d - s o l u b l e metals As, Cd, C r , Cu and Pb, an a l i q u o t o f t h e f i l t r a t e must be t r e a t e d w i t h t h e a p p r o p r i a t e m a t r i x m o d i f i e r s b e fo re a n a l y s i s . For proper i n s t r u m e n t a l STGFAA c a l i b r a t i o n and suggested o p e ra ti n g c o n d i t i o n s see Method 200.9 o f t h i s manual. I n t h e absence o f an e s t a b l i s h e d MDL (Sect. lO.Z.l), t h e f o l l o w i n g estimated STGFAA i n s t r u m e n t a l d e t e c t i o n 1 i m i t f o r each element should be considered t h e l i m i t o f anaysis. Element As Cd Cr cu

Estimated D e t e c t i o n L i m i t UQ/L

0.9 0.05 0.2 1.0

10


12

CALCULATIONS 12.1 See the appropriate section o f the recornmended methods o f analysis. 12.2 Final results o f these calculations should be reported as mg/L acid-

soluble metal. 13

PRECISION AND RECOVERY 13.1 Precision and recovery data for Cd, Cr, Cu, and Pb by this method u s i n g inductively coupled plasma-atomic emission spectrometric analyses are given in Table 1. The data are for three levels of concentration using varying amounts o f the same sludge material

spiked into river water. Seven replicate samples were prepared for each level o f concentration. River water controls were subtracted from each level of spike. The percent recovery calculation i s based on "total-recoverable" analysis o f the same samples. Accuracy data on actual samples cannot be obtained.

13.2 Precision data on the determination of acid-soluble metals by this method using atomic absorption spectrophotometric analyses are estimated to be similar to the data in the methods referenced. 14.

REFERENCES 1.

Water Quality Criteria; Availability o f Documents, Federal Register, Vol. 50, NO. 145, July 29, 1985, pp. 30784-30796.

2.

Chemical Analysis o f Water and Wastes, EPA 600/4-79-020, (Revised, March 1983), U . S . Environmental Protection Agency, Office of Research and Development, Environmental Monitoring and Support Laboratory, Cincinnati, Ohio.

3.

Annual Book o f ASTM Standards, Part 31, American Society for Testing and Materials, 1916 Race St., Philadelphia, PA, 19103.

4.

Code of Federal Regulations 40, Ch. 1, Pt. 136 Appendix B.

TABLE 1.

2.5 g

PERCENT RECOVERY(') OF ACID SOLUBLE METALS") FROM SLUDGE MATERIAL SPIKED I N R I V E R WATER

Sludge/L

1 .O g S1 udge/L

Acid S o l u b l e Total Recoverable Mean mq/L Metal ms/L

1. 2.

Std.

Dev.

0.25 g Sludge/L

Acid S o l u b l e

Total Percent Recoverable Recovery mq/L

Mean

Acid S o l u b l e

mq/L

Std. Dev.

Percent Recovery

Total Recoverable ms/L

Mean

Std.

mq!L

Dev.

Percent Recovery

Cd

0.085

0.074

f0.002

87%

0.036

0.030

f0.002

83%

0.010

0.009 fO.OO1

90%

Cr

7.48

3.18

f0.085

43%

3.28

1.21

f0.070

37%

0.669

0.326 f0.032

49%

cu

1.17

1.11

f0.025

95%

0.502

0.442

f0.019

88%

0.130

0.115 f0.006

88%

Pb

0.601

0.311

fO.O1O

52%

0.268

0.137

f0.008

51%

0.067

0.042 i0.007

63%

P e r c e n t r e c o v e r y i s based on the " t o t a l r e c o v e r a b l e " v a l u e All d a t a o b t a i n e d from I C P a n a l y s e s .

12


METHOD 200.2 SAMPLE PREPARATION PROCEDURE FOR SPECTROCHEMICAL DETERMINATION OF TOTAL RECOVERABLE ELEMENTS

Revision 2.8 EMMC Version

T.D. Martin, E.R. Martin, and S . E . Long (Technology Applications, Inc.) Method 200.2, Revision 1.1 (1989)

T.D. Martin, S.E. Long (Technology Applications Inc.), and J.T. Creed Method 200.2, Revision 2.3 (1991) T.D. Martin, J.T. Creed, and C.A. Brockhoff (1994)

-

Method 200.2, Revision 2.8

ENVIRONMENTAL MONITORING SYSTEMS LABORATORY OFFICE OF RESEARCH AND DEVELOPMENT U. S. ENVIRONMENTAL PROTECTION AGENCY C I N C I N N A T I , OHIO 45268

-

Metals

13

METHOD 200.2 SAMPLE PREPARATION PROCEDURE FOR SPECTROCHEMICAL DETERMINATION OF TOTAL RECOVERABLE ELEMENTS

1.0 SCOPE AND APPLICATION 1.1 T h i s method p r o v i d e s sample p r e p a r a t i o n p r o c e d u r e s f o r t h e d e t e r m i n a t i o n o f t o t a l recoverable analytes i n groundwaters, surface w a t e r s , d r i n k i n g w a t e r s , w a s t e w a t e r s , and, w i t h t h e e x c e p t i o n o f s i l i c a , i n s o l i d t y p e samples such as s e d i m e n t s , s l u d g e s and s o i l s . Aqueous samples c o n t a i n i n g suspended o r p a r t i c u l a t e m a t e r i a l 2 1% ( W / V ) s h o u l d b e e x t r a c t e d as a s o l i d t y p e sample. T h i s method i s a p p l i c a b l e t o the following analytes: Chemical A b s t r a c t S e r v i c e s R e g i s t r y Numbers (CASRN)

Analyte

7429-90-5 7440-36-0 7440-38-2 7440-42-8 7440-39-3 7440-41-7 7440-43-9 7440-70-2 7440-47-3 7440-48-4 7440-50-8 7439-89-6 7439-92-1 7439-93-2 7439-95-4 7439-96-5 7439-97-6 7439-98-7 7440-02-0 7723-14-0 7440-09-7 7782-49-2 7631-86-9 7440-22-4 7440-23-5 7440-24-6

A1 umi num A n t i mony Arsenic Boron B a r i um B e r y l 1 ium Cadmi um Calcium Chromi um Cobalt Copper

Iron Lead Lithium Magnesi urn Manganese Mercury Molybdenum Nickel Phosphorus P o t ass ium S e l e n i urn S i l icaa S i 1v e r Sod iurn S t r o n t ium ( c o n t i n u e s on n e x t page) ~

a

T h i s method i s

~~~

not s u i t a b l e

~

f o r the determination o f s i l i c a i n solids.

R e v i s i o n 2.8 Hay 1994

14


C hem ic a 1 Ab s t r a c t Se r v ic e s

Anal y t e

R e g i s t r y Numbers (CASRN)

7440-28-0 7440-29-1 7440-3 1-5 7440-61-1 7440-62-2 7440-66-6

1.2

F o r r e f e r e n c e where t h i s method i s a p p r o v e d f o r use i n c o m p l i a n c e m o n i t o r i n g programs [ e . g . , C l e a n Water A c t (NPDES) o r S a f e D r i n k i n g Water A c t (SDWA)] c o n s u l t b o t h t h e a p p r o p r i a t e s e c t i o n s o f t h e Code o f f e d e r a l R e g u l a t i o n (40 CFR P a r t 136 T a b l e 1B f o r NPDES, and P a r t 141 § 141.23 f o r d r i n k i n g w a t e r ) , and t h e l a t e s t F e d e r a l R e g i s t e r announcements.

1.3

Samples p r e p a r e d b y t h i s method c a n be a n a l y z e d b y t h e f o l l o w i n g methods g i v e n i n t h i s s u p p l e m e n t : Method 200.7, D e t e r m i n a t i o n o f M e t a l s and T r a c e E l e m e n t s b y I n d u c t i v e l y Coup ed 'Plasma-Atomic E m i s s i o n S p e c t r o m e t r y ; Method 200.8, D e t e r m i n a t i o n o f T r a c e Elements By I n d u c t i v e l y Coupled Plasma-Mass S p e c t r o m e t r y ; ind Method 200.9, D e t e r n i i n a t i o n o f T r a c e Elements by S t a b i l i z e d T e m p e r a t u r e G r a p h i t e F u r n a c e A t o m i c A b s o r p t i o n S p e c t r o m e t r y . A l s o , t h i s method can be used p r i o r t o a n a l y s i s by d i r e c t a s p i r a t i o n f l a m e a t o m i c a b s o r p t i o n f o r t h e above l i s t o f a n a l y t e s w i t h t h e e x c e p t i o n o f t h e f o l l o w i n g : As, B, Hg, P, Se, SiO,, Th, and U.

1.4

The p r e p a r a t i o n p r o c e d u r e s d e s c r i b e d i n t h i s method a r e not recommended p r i o r t o a n a l y s i s by t h e c o n v e n t i o n a l g r a p h i t e f u r n a c e t e c h n i q u e , commonly r e f e r e d t o as " o f f - t h e - w a l l " , n o n - p l a t f o r m o r non-delayed a t o m i z a t i o n . I t i s b e l i e v e d t h a t t h e r e s u l t i n g c h l o r i d e c o n c e n t r a t i o n i n t h e p r e p a r e d s o l u t i o n s c a n cause e i t h e r a n a l y t e v o l a t i l i z a t i o n l o s s p r i o r t o a t o m i z a t i o n o r an u n r e m e d i a b l e c h e m i c a l v a p o r s t a t e i n t e r f e r e n c e f o r some a n a l y t e s when a n a l y z e d u s i n g t h e conventional graphite furnace technique.

1.5

T h i s method i s s u i t a b l e f o r p r e p a r a t i o n o f aqueous samples c o n t a i n i n g s i l v e r c o n c e n t r a t i o n s up t o 0 . 1 mg/L. f o r t h e a n a l y s i s o f w a s t e w a t e r samples c o n t a i n i n g h i g h e r c o n c e n t r a t i o n s o f s i l v e r , s u c c e e d i n g s m a l l e r volume, w e l l m i x e d a l i q u o t s must be p r e p a r e d u n t i l t h e a n a l y s i s s o l u t i o n c o n t a i n s < 0 . 1 mg/L s i l v e r . The e x t r a c t i o n o f s o l i d samples c o n t a i n i n g c o n c e n t r a t i o n s o f s i l v e r > 50 mg/kg s h o u l d be t r e a t e d i n a s i m i l a r manner. A l s o , t h e e x t r a c t i o n o f t i n f r o m s o l i d samples s h o u l d be p r e p a r e d a g a i n u s i n g a l i q u o t s < 1 g when d e t e r m i n e d sample c o n c e n t r a t i o n s exceed 1%.

1.6

When u s i n g t h i s method f o r d e t e r m i n a t i o n o f b o r o n and s i l i c a i n aqueous samples, o n l y p l a s t i c o r q u a r t z l a b w a r e s h o u l d be used f r o m R e v i s i o n 2 . 8 May1994

Metals

15

t h e t i m e o f sample c o l l e c t i o n t o t h e c o m p l e t i o n o f t h e a n a l y s i s . F o r a c c u r a t e d e t e r m i n a t i o n s o f b o r o n i n s o l i d samples o n l y q u a r t z o r PTFE b e a k e r s s h o u l d be used d u r i n g a c i d e x t r a c t i o n w i t h immediate t r a n s f e r o f an e x t r a c t a l i q u o t t o a p l a s t i c c e n t r i f u g e t u b e f o l l o w i n g d i l u t i o n o f t h e e x t r a c t t o volume. When p o s s i b l e , b o r o s i l i c a t e g l a s s s h o u l d be avoided t o prevent contamination o f these a n a l y t e s .

2.0

1.7

T h i s method w concentrations analysis o f concentrations possible a f t e r

i l l s o l u b i l i z e and h o l d i n s o l u t i o n o n l y o f barium i n t h e presence o f f r e e s u l f a t e . b a r i u m i n samples h a v i n g v a r y i n g and o f s u l f a t e , a n a l y s i s s h o u l d be c o m p l e t e d as sample p r e p a r a t i o n .

1.8

T h i s method i s n o t s u i t a b l e f o r t h e d e t e r m i n a t i o n o f v o l a t i l e l o w b o i l i n g p o i n t o r g a n o - m e r c u r y compounds.

minimal For the unknown soon as

SUMMARY OF METHOD 2.1

S o l i d and aqueous samples a r e p r e p a r e d i n a s i m i l a r manner f o r a n a l y s i s . N i t r i c and h y d o c h l o r i c a c i d s a r e d i s p e n s e d i n t o a b e a k e r c o n t a i n i n g an a c c u r a t e l y weighed o r measured, w e l l mixed, homogeneous aqueous o r s o l i d sample. Aqueous samples a r e f i r s t r e d u c e d i n volume b y g e n t l e h e a t i n g . Then, m e t a l s and t o x i c e l e m e n t s a r e e x t r a c t e d f r o m e i t h e r s o l i d samples o r t h e u n d i s s o l v e d p o r t i o n o f aqueous samples b y c o v e r i n g t h e b e a k e r w i t h a w a t c h g l a s s and r e f l u x i n g t h e sample i n t h e A f t e r extraction, the solubilzed d i l u t e a c i d m i x t u r e f o r 30 m i n . a n a l y t e s a r e d i l u t e d t o s p e c i f i e d volumes w i t h ASTM t y p e I w a t e r , m i x e d and e i t h e r c e n t r i f u g e d o r a l l o w e d t o s e t t l e o v e r n i g h t b e f o r e a n a l y s i s . D i l u t e d samples a r e t o be a n a l y z e d b y t h e a p p r o p r i a t e mass a n d / o r a t o m i c s p e c t r o m e t r y methods as soon as p o s s i b l e a f t e r preparation.

3.0 DEFINITIONS 3.1

F i e l d Reagent B l a n k (FRB) - An a l i q u o t o f r e a g e n t w a t e r o r o t h e r b l a n k m a t r i x t h a t i s p l a c e d i n a sample c o n t a i n e r i n t h e l a b o r a t o r y and t r e a t e d a s a sample i n a l l r e s p e c t s , i n c l u d i n g s h i p m e n t t o t h e sampling s i t e , exposure t o t h e sampling s i t e c o n d i t i o n s , storage, p r e s e r v a t i o n , and a l l a n a l y t i c a l p r o c e d u r e s . The p u r p o s e o f t h e FRB i s t o d e t e r m i n e i f method a n a l y t e s o r o t h e r i n t e r f e r e n c e s a r e p r e s e n t i n t h e f i e l d environment (Sect 8.3).

3.2

S o l i d Sample - F o r t h e p u r p o s e o f t h i s method, a sample t a k e n f r o m m a t e r i a l c l a s s i f i e d as e i t h e r s o i l , s e d i m e n t o r s l u d g e .

3.3

T o t a l R e c o v e r a b l e A n a l y t e - The c o n c e n t r a t i o n o f a n a l y t e d e t e r m i n e d t o be i n e i t h e r a s o l i d sample o r an u n f i l t e r e d aqueous sample f o l l o w i n g t r e a t m e n t by r e f l u x i n g w i t h h o t d i l u t e m i n e r a l a c i d .

3.4

W a t e r Sample - F o r t h e p u r p o s e o f t h i s method, a sample t a k e n f r o m one o f t h e f o l l o w i n g sources: d r i n k i n g , s u r f a c e , ground, storm r u n o f f , i n d u s t r i a l o r domestic wastewater.

R e v i s i o n 2.8 Hay 1994

16 4.0

Methods for the Determination INTERFERENCES

4.1

In sample preparation, contamination i s of pt I I I W (ori(ern. The hork area, including bench top and fume hood, should be periodically cleaned in order to eliminate environmental cont 2 , more acid must be added and the sample held for sixteen hours until verified to be pH < 2. If properly acid preserved, the sample can be held up to 6 months before anal ys i s . NOTE:

When the nature of the sample is either unknown or is known to be hazardous, acidification should be done in a fume hood. See Section 5.2. Revision2.8 May1994

Metals

19

8.2 Solid samples require no preservation prior to analysis other than storage at 4 ° C . There is no established holding time limitation for solid samples. 8.3 For aqueous samples, a field blank should be prepared and analyzed as required by the data user. Use the same container and acid as used in sample col lect ion. 9.0 OUALITY CONTROL

9.1 Each laboratory determining total recoverable elements is required to operate a formal quality control ( Q C ) program. The minimum requirements of a Q C program consist of an initial demonstration of laboratory capability, and the analysis of laboratory reagent blanks, fortified blanks and quality control samples as a continuing check on performance. The laboratory is required to maintain performance records that define the quality of data generated. 9.2 Specific instructions on accomplishing the described aspects of the QC program are discussed in the analytical methods (Sect. 1.3). 10.

CALIBRATION AND STANDARDIZATION 10.1 Not applicable. selected.

Follow instructions given in the analytical method

11.0 PROCEDURE

11.1 Aqueous Sample Preparation - Total Recoverable Analytes 11.1.1

For the determination of total recoverable analytes in aqueous samples, transfer a 100 mL (k 1 mL) aliquot from a well mixed, acid preserved sample to a 250-mL Griffin beaker (Sects. 1.2, 1.5, 1.6, 1.7, & 1.8). (When necessary, smaller sample aliquot volumes may be used.) NOTE:

If the sample contains undissolved solids > 1%, a well mixed, acid preserved aliquot containing no more than 1 g particulate material should be cautiously evaporated to near 10 mL and extracted using the acidmixture procedure described in Sections 11.2.3 thru 11.2.8.

11.1.2 Add 2 mL (ltl) nitric acid and 1.0 mL of (ltl) hydrochloric acid to the beaker containing the measured volume of sample. Place the beaker on the hot plate for solution evaporation. The hot plate should be located in a fume hood and previously adjusted to provide evaporation at a temperature of approximately but no higher than 8 5 ° C . (See the following note.) The beaker should be covered with an elevated watch glass or other necessary steps should be taken to prevent sample contamination from the fume hood environment.

Revision2.8 May1994

20

Methods for the Determination NOTE:

For p r o p e r h e a t i n g a d j u s t t h e temperature c o n t r o l o f t h e h o t p l a t e such t h a t an uncovered G r i f f i n beaker c o n t a i n i n g 50 mL o f w a t e r p l a c e d i n t h e c e n t e r o f t h e h o t p l a t e can be m a i n t a i n e d a t a temperature a p p r o x i m a t e l y b u t no h i g h e r t h a n 85°C. (Once t h e beaker i s covered w i t h a watch g l a s s t h e temperature o f t h e w a t e r w i l l r i s e t o a p p r o x i m a t e l y 95°C.)

11.1.3

Reduce t h e volume o f t h e sample a l i q u o t t o about 20 mL by g e n t l e h e a t i n g a t 85°C. DO NOT B O I L . T h i s s t e p t a k e s about 2 h f o r a 100 mL a l i q u o t w i t h t h e r a t e o f e v a p o r a t i o n r a p i d l y i n c r e a s i n g as t h e sample volume approaches 20 mL. (A spare beaker c o n t a i n i n g 20 mL o f w a t e r can be used as a gauge.)

11.1.4

Cover t h e l i p o f t h e beaker w i t h a watch g l a s s t o reduce a d d i t i o n a l e v a p o r a t i o n and g e n t l y r e f l u x t h e sample f o r 30 m i n u t e s . ( S l i g h t b o i l i n g may occur, b u t v i g o r o u s b o i l i n g must be avoided t o p r e v e n t l o s s o f t h e HC1-H,O azeotrope.)

11.1.5

A l l o w t h e beaker t o c o o l . Q u a n t i t a t i v e l y t r a n s f e r t h e sample s o l u t i o n t o a 50-mL v o l u m e t r i c f l a s k , make t o volume w i t h r e a g e n t w a t e r , s t o p p e r and m i x .

11.1.6

A l l o w any u n d i s s o l v e d m a t e r i a l t o s e t t l e o v e r n i g h t , o r c e n t r i f u g e a p o r t i o n o f t h e p r e p a r e d sample u n t i l c l e a r . ( I f a f t e r c e n t r i f u g i n g o r s t a n d i n g o v e r n i g h t t h e sample c o n t a i n s suspended s o l i d s t h a t would c l o g t h e n e b u l i z e r , a p o r t i o n o f t h e sample may be f i l t e r e d f o r t h e i r removal p r i o r t o analysis. However, c a r e should be e x e r c i s e d t o a v o i d p o t e n t i a l c o n t a m i n a t i o n f r o m f i l t r a t i o n . ) The sample i s now r e a d y f o r a n a l y s i s by e i t h e r i n d u c t i v e l y coupled plasma-atomic e m i s s i o n s p e c t r o m e t r y o r d i r e c t a s p i r a t i o n f l a m e and s t a b i l i z e d t e m p e r a t u r e g r a p h i t e f u r n a c e atomic a b s o r p t i o n spectroscopy ( S e c t s . 1.3 & 1 . 4 ) .

11.1.7

To r e a d y t h e sample f o r analyses by i n d u c t i v e l y coupled plasma-mass s p e c t r o m e t r y ( S e c t . 1 . 3 ) , a d j u s t t h e c h l o r i d e c o n c e n t r a t i o n by p i p e t t i n g 20 mL o f t h e p r e p a r e d s o l u t i o n i n t o a 50-mL v o l u m e t r i c f l a s k , d i l u t e t o volume w i t h r e a g e n t w a t e r and m i x . ( I f the dissolved s o l i d s i n t h i s s o l u t i o n are > 0.2%, a d d i t i o n a l d i l u t i o n may be r e q u i r e d t o p r e v e n t c l o g g i n g o f t h e e x t r a c t i o n and/or skimmer cones. I n t e r n a l standards a r e added a t t h e t i m e o f a n a l y s i s . )

11.1.8

Because t h e e f f e c t s o f v a r i o u s m a t r i c e s on t h e s t a b i l i t y o f d i l u t e d samples cannot be c h a r a c t e r i z e d , a l l analyses s h o u l d be performed as soon as p o s s i b l e a f t e r t h e completed preparation.

11.2 S o l i d Sample P r e p a r a t i o n - T o t a l Recoverable A n a l y t e s 11.2.1

For t h e d e t e r m i n a t i o n o f t o t a l r e c o v e r a b l e a n a l y t e s i n s o l i d samples, m i x t h e sample t h o r o u g h l y and t r a n s f e r a p o r t i o n R e v i s i o n 2.8 May 1994

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21

( > 20 g ) t o t a r e d w e i g h i n g d i s h , weigh t h e sample and r e c o r d ( f o r samples w i t h < 35% m o i s t u r e a 20 g the w e t weight. portion i s sufficient. For samples w i t h m o i s t u r e > 35% a l a r g e r a l i q u o t 5 0 - 1 0 0 g i s r e q u i r e d . ) Dry t h e sample t o a c o n s t a n t w e i g h t a t 60°C and r e c o r d t h e d r y w e i g h t f o r c a l c u l a t i o n o f percent s o l i d s (Sect. 1 2 . 1 ) . (The sample i s d r i e d a t 60°C t o p r e v e n t t h e l o s s o f mercury and o t h e r p o s s i b l e v o l a t i l e m e t a l l i c compounds, t o f a c i l i t a t e s i e v i n g , and t o ready t h e sample f o r g r i n d i n g . )

11.2.2

To achieve homogeneity, s i e v e t h e d r i e d sample u s i n g a 5-mesh p o l y p r o p y l e n e s i e v e and g r i n d i n a m o r t a r and p e s t l e . (The s i e v e , m o r t a r and p e s t l e s h o u l d be cleaned between samples.) From t h e d r i e d , ground m a t e r i a l weigh a c c u r a t e l y a r e p r e s e n t a t i v e 1.0 f 0.01 g a l i q u o t ( W ) o f t h e sample and t r a n s f e r t o a 250-mL P h i l l i p s beaker f o r a c i d e x t r a c t i o n (Sects. 1.5, 1.6, 1.7, & 1 . 8 ) .

11.2.3

To t h e beaker add 4 mL o f (ltl) HNO, and 10 mL o f ( 1 t 4 ) HC1. Cover t h e l i p o f t h e beaker w i t h a watch g l a s s . Place t h e beaker on a h o t p l a t e f o r r e f l u x e x t r a c t i o n o f t h e a n a l y t e s . The h o t p l a t e s h o u l d be l o c a t e d i n a fume hood and p r e v i o u s l y adjusted t o provide a r e f l u x temperature o f approximately 95OC. (See t h e f o l l o w i n g n o t e . )

NOTE:

For proper heating i d j u s t the temperature c o n t r o l o f t h e h o t p l a t e such t h a t an uncovered G r i f f i n beaker c o n t a i n i n g 50 mL o f w a t e r p l a c e d i n t h e c e n t e r o f t h e h o t p l a t e can be m a i n t a i n e d a t a t e m p e r a t u r e a p p r o x i m a t e l y b u t no h i g h e r t h a n 85OC. (Once t h e beaker i s covered w i t h a watch g l a s s t h e t e m p e r a t u r e o f t h e w a t e r w i l l r i s e t o a p p r o x i m a t e l y 95OC.) A l s o , a b l o c k d i g e s t e r c a p a b l e o f m a i n t a i n i n g a t e m p e r a t u r e o f 95OC and equipped w i t h 250-mL c o n s t r i c t e d v o l u m e t r i c d i g e s t i o n tubes may be s u b s t i t u t e d f o r t h e h o t p l a t e and c o n i c a l beakers i n t h e e x t r a c t i o n s t e p .

11.2.4

Heat t h e sample and g e n t l y r e f l u x f o r 30 min. Very s l i g h t b o i l i n g may o c c u r , however v i g o r o u s b o i l i n g must be avoided t o p r e v e n t l o s s o f t h e HC1-H,O azeotrope. Some s o l u t i o n e v a p o r a t i o n w i l l o c c u r ( 3 t o 4 mL).

11.2.5

A l l o w t h e sample t o c o o l and q u a n t i t a t i v e l y t r a n s f e r t h e e x t r a c t t o a 100-mL v o l u m e t r i c f l a s k . D i l u t e t o volume w i t h r e a g e n t w a t e r , s t o p p e r and m i x .

11.2.6

A l l o w t h e sample e x t r a c t s o l u t i o n t o s t a n d o v e r n i g h t t o separate i n s o l u b l e m a t e r i a l o r centrifuge a p o r t i o n o f t h e sample s o l u t i o n u n t i l c l e a r . ( I f after centrifuging or s t a n d i n g o v e r n i g h t t h e e x t r a c t s o l u t i o n c o n t a i n s suspended s o l i d s t h a t would c l o g t h e n e b u l i z e r , a p o r t i o n o f t h e e x t r a c t s o l u t i o n may be f i l t e r e d f o r t h e i r removal p r i o r t o a n a l y s i s . However, c a r e s h o u l d be e x e r c i s e d t o a v o i d p o t e n t i a l c o n t a m i n a t i o n from f i l t r a t i o n . ) The sample i s now ready f o r R e v i s i o n 2 . 8 May1994

22

Methods for the Determination a n a l y s i s by e i t h e r i n d u c t i v e l y coupled plasma-atomic e m i s s i o n s p e c t r o m e t r y o r d i r e c t a s p i r a t i o n flame and s t a b i l i z e d t e m p e r a t u r e g r a p h i t e f u r n a c e atomic a b s o r p t i o n spectroscopy (Sects. 1 . 3 & 1.4). 11.2.7

To ready t h e sample f o r analyses by i n d u c t i v e l y c o u p l e d plasma-mass s p e c t r o m e t r y ( S e c t . 1 . 3 ) , a d j u s t t h e c h l o r i d e c o n c e n t r a t i o n by p i p e t t i n g 10 mL o f t h e prepared s o l u t i o n i n t o a 50-mL v o l u m e t r i c f l a s k , d i l u t e t o volume w i t h r e a g e n t w a t e r and m i x . ( I f the dissolved s o l i d s i n t h i s s o l u t i o n are > 0.2%, a d d i t i o n a l d i l u t i o n may be r e q u i r e d t o p r e v e n t c l o g g i n g o f t h e e x t r a c t i o n and/or skimmer cones. I n t e r n a l standards a r e added a t t h e t i m e o f a n a l y s i s . )

11.2.8

Because t h e e f f e c t s o f v a r i o u s m a t r i c e s on t h e s t a b i l i t y o f d i l u t e d samples cannot be c h a r a c t e r i z e d , a l l analyses s h o u l d be performed as soon as p o s s i b l e a f t e r t h e completed preparation,

11.3 Sample A n a l y s i s - Use an a n a l y t i c a l method l i s t e d i n S e c t . 1.3.

12.0 DATA ANALYSIS AND CALCULATIONS 12.1 To r e p o r t p e r c e n t s o l i d s i n s o l i d samples ( S e c t . 11.2) c a l c u l a t e as f o l 1ows : % s o l i d s (S)

=

DW - x 100

ww

where:

DW WW

NOTE:

If t h e d a t a u s e r , program o r l a b o r a t o r y r e q u i r e s t h a t t h e r e p o r t e d p e r c e n t s o l i d s be determined by d r y i n g a t 105"C, r e p e a t t h e p r o c e d u r e g i v e n i n S e c t i o n 11.2.1 u s i n g a s e p a r a t e p o r t i o n ( > 20 g ) o f t h e sample and d r y t o c o n s t a n t w e i g h t a t 103-105°C.

= Sample w e i g h t ( 9 ) d r i e d a t 6OoC = Sample w e i g h t (9) b e f o r e d r y i n g

12.2 C a l c u l a t i o n and t r e a t m e n t o f d e t e r m i n e d a n a l y t e d a t a a r e d i s c u s s e d i n a n a l y t i c a l methods l i s t e d i n S e c t . 1.3.

13.0 METHOD PERFORMANCE 13.1 Not a p p l i c a b l e . i n S e c t . 1.3.

A v a i l a b l e d a t a i n c l u d e d i n a n a l y t i c a l methods l i s t e d

14.0 POLLUTION PREVENTION

14.1 P o l l u t i o n p r e v e n t i o n encompasses any t e c h n i q u e t h a t reduces o r e l i m i n a t e s t h e q u a n t i t y o r t o x i c i t y o f waste a t t h e p o i n t o f g e n e r a t i o n . Numerous o p p o r t u n i t i e s f o r p o l l u t i o n p r e v e n t i o n e x i s t i n l a b o r a t o r y o p e r a t i o n . The EPA has e s t a b l i s h e d a p r e f e r r e d h i e r a r c h y o f e n v i r o n m e n t a l management t e c h n i q u e s t h a t p l a c e s p o l l u t i o n R e v i s i o n 2.8 Hay 1994

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23

prevention as the management option of first choice. Whenever feasible, laboratory personnel should use pollution prevention techniques to address their waste generation. When wastes cannot be feasibly reduced at the source, the Agency recommends recycling as the next best option. 14.2 For information about pollution prevention that may be applicable to laboratories and research institutions, consult less i s Better: Laboratory Chemical Management for Waste Reduction, available from the American Chemical Society's Department of Government Relations and Science Policy, 1155 16th Street N . W . , Washington D.C. 20036, (202)872-4477. 15.0 YASTE MANAGEMENT 1 5 . 1 The Environmental Protection Agency requires that laboratory waste

management practices be conducted consistent with all applicable rules and regulations. The Agency urges laboratories to protect the air, water, and land by minimizing and controlling all releases from hoods and bench operations, complying with the letter and spirit of any sewer discharge permits and regulations, and by complying with all solid and hazardous waste regulations, particularly the hazardous waste identification rules and land disposal restrictions. For further information on waste management consult The Waste Management Manual for Laboratory Personnel, ayailable from the American Chemical Society at the address listed in the Section 14.2. 16.0 REFERENCES

1.

Martin, T.D. and E.R. Martin, "Evaluation o f Method 200.2 Sample Preparation Procedure for Spectrochemical Analyses o f Total Recoverable Elements," December 1989, U.S. Environmental Protection Agency, Office of Research and Development, Environmental Monitoring Systems Laboratory, Cincinnati, Ohio 45268.

2.

"OSHA Safety and Health Standards, General Industry," (29 CFR 1910), Occupational Safety and Health Administration, OSHA 2206, revised January 1976.

3.

"Safety in Academic Chemistry Laboratories," American Chemical Society Publication, Committee on Chemical Safety, 3rd Edition, 1979.

4.

"Proposed OSHA Safety and Health Standards, Laboratories," Occupational Safety and Health Administration, Federal Register, July 24, 1986.

5.

Annual Book of ASTM Standards, Volume 11.01

Revision 2.8 May 1994

24

Methods for the Determination METHOD 200.3 SAMPLE PREPARATION PROCEDURE FOR SPECTROCHEMICAL DETERMINATION OF TOTAL RECOVERABLE ELEMENTS I N BIOLOGICAL TISSUES

W i 11 iam McDaniel

U.

Environmental Services D i v i s i o n Region I V S . Environmental P r o t e c t i o n Agency

Revision 1.0 A p r i l 1991

Adapted by:

ENVIRONMENTAL MONITORING SYSTEMS LABORATORY OFFICE OF RESEARCH AND DEVELOPMENT U. S . ENVIRONMENTAL PROTECTION AGENCY CINCINNATI, OHIO 45268

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25

METHOD 200.3 SAMPLE PREPARATION PROCEDURE FOR SPECTROCHEMICAL DETERMINATION OF TOTAL RECOVERABLE ELEMENTS I N BIOLOGICAL TISSUES 1.

SCOPE AND APPLICATION 1.1 This method provides sample preparation procedures for the

determination o f total recoverable elements in biological tissue samples. 1.2

This method is applicable to the following elements: Analvte A1 umi num Antimony Arsenic Bar i um Beryl 1 i um Cadmi um Calcium Chromium Cobalt Copper Iron Lead Lithium Magnesium Manganese Mercury Molybdenum Nickel Phosphorus Potass i um Selenium S i 1 ver Sod i um Stront i um Thallium Thori um Uranium Vanadium Zinc

1.3

Chemical Abstract Services Reaistry Numbers (CASRNI 7429-90-5 7440-36-0 7440-38-2 7440-39-3 7440-41-7 7440-43-9 7440-70-2 2440-47-3 7440-48-4 7440-50-8 7439-89-6 7439-92-1 7439-93-2 7439-95-4 7439-96-5 7439-97-6 7439-98- 7 7440-02-0 7723-14-0 7440-09-7 7782-49-2 7440-22-4 7440-23-5 7440-24-6 7440-28-0 7440-29-1 7440-61- 1 7440-62-2 7440-66-6

Samples prepared by this method can be analyzed by inductively coupled plasma-atomic emission spectrometry (ICP-AES) Method 2 0 0 . 7 , "Determination of Metals and Trace Elements by Inductively Coupled Plasma-Atomic Emission Spectrometry," inductively coupled plasmamass spectrometry (ICP-MS) Method 200.8, "Determination of Metals

Methods for the Determination and Trace Elements by I n d u c t i v e l y Coupled Plasma-Mass S p e c t r o m e t r y , " and s t a b i l i z e d t e m p e r a t u r e p l a t f o r m g r a p h i t e f u r n a c e a t o m i c a b s o r p t i o n (STGFAA), Method 200.9, " D e t e r m i n a t i o n o f Trace Elements by S t a b i l i z e d Temperature G r a p h i t e Furnace Atomic A b s o r p t i o n S p e c t r o m e t r y " . See a n a l y t i c a l methods mentioned f o r s e l e c t i o n o f t h e a p p r o p r i a t e method f o r d e t e r m i n a t i o n o f a s p e c i f i c a n a l y t e . SUMMARY OF METHOD

2.1

Up t o 5 g o f a f r o z e n t i s s u e sample i s t r a n s f e r r e d t o a 125 mL f l a s k . The t i s s u e i s d i g e s t e d w i t h n i t r i c a c i d , hydrogen p e r o x i d e and h e a t . T h i s d i g e s t i o n r e s u l t s i n a c l e a r s o l u t i o n t h a t i s t h e n analyzed by mass o r a t o m i c s p e c t r o m e t r y methods. The d e t e r m i n e d metal c o n c e n t r a t i o n i s r e p o r t e d i n microgram/gram ( p g / g ) wet t i s s u e weight.

DEFINITIONS

3.1

TOTAL RECOVERABLE - The c o n c e n t r a t i o n o f a n a l y t e d e t e r m i n e d t o be i n e i t h e r a s o l i d sample o r an u n f i l t e r e d aqueous sample f o l l o w i n g t r e a t m e n t by r e f l u x i n g w i t h h o t d i l u t e m i n e r a l a c i d .

3.2

LABORATORY REAGENT BLANK (LRB) - A s o l u t i o n o f r e a g e n t s t h a t i s t r e a t e d e x a c t l y as a sample i n c l u d i n g exposure t o a l l g l a s s w a r e and equipment t h a t a r e used w i t h o t h e r samples. The LRB i s used t o d e t e r m i n e i f method a n a l y t e s o r o t h e r i n t e r f e r e n c e s a r e p r e s e n t i n t h e l a b o r a t o r y environment, r e a g e n t s , o r apparatus.

INTERFERENCES

4.1

Chromium c o n t a m i n a t i o n o f b i o l o g i c t l samples f r o m t h e use o f s t a i n l e s s s t e e l has been r e p o r t e d . Use o f s p e c i a l c u t t i n g implements and d i s s e c t i n g board made f r o m m a t e r i a l s t h a t a r e n o t o f i n t e r e s t i s recommended. K n i f e b l a d e s made o f t i t a n i u m w i t h T e f l o n handles have been s u c c e s s f u l l y used.

4.2

I n sample p r e p a r a t i o n , c o n t a m i n a t i o n i s o f p r i m e concern. The work area, i n c l u d i n g bench t o p and fume hood, s h o u l d be p e r i o d i c a l l y cleaned i n o r d e r t o e l i m i n a t e e n v i r o n m e n t a l c o n t a m i n a t i o n .

4.3

Chemical i n t e r f e r e n c e s a r e m a t r i x dependent and cannot be p r e d i c t e d .

5.1

A l l personnel h a n d l i n g e n v i r o n m e n t a l samples known t o c o n t a i n o r t o have been i n c o n t a c t w i t h human waste s h o u l d be immunized a g a i n s t known d i s e a s e c a u s a t i v e agents.

5.2

M a t e r i a l s a f e t y d a t a sheets f o r a l l chemical r e a g e n t s s h o u l d be a v a i l a b l e t o and understood by a l l personnel u s i n g t h i s method. Concentrated n i t r i c and h y d r o c h l o r i c a c i d s a r e m o d e r a t e l y t o x i c and e x t r e m e l y i r r i t a t i n g t o s k i n and mucus membranes. Hydrogen p e r o x i d e

Metals

27

is a strong oxidizing reagent. Use these reagents in a hood whenever possible and if eye or skin contact occurs, flush with large volumes of water. Always wear safety glasses or a shield for eye protection when working with these reagents. 6.

APPARATUS AND EQUIPMENT

6.1 LABWARE - For determination of trace levels o f elements, contamination and loss are o f prime consideration. Potential contamination sources include improperly cleaned laboratory apparatus and general contamination within the laboratory environment from dust, etc. A clean laboratory work area designated for trace element sample handling must be used. Sample containers can introduce positive and negative errors in the determination of trace elements by contributing contaminants through surface desorption/leaching, or depleting element concentrations through adsorption processes. All reusable labware (glass, quartz, polyethylene, Teflon, etc.), including the sample container, should be cleaned prior to use or shown to be contaminant free. Labware should be soaked overnight and thoroughly washed with laboratorygrade detergent and water, rinsed with water, and soaked for four hours in a mixture of dilute nitric and hydrochloric acid (1+2+9), followed by rinsing with water, ASTM type I water and oven drying. NOTE:

Chromic acid must not be used for cleaning glassware.

6.1.1 Glassware - Volumetric flasks, graduated cylinders and 125-mL Erlenmeyer fl asks,

6.1.2 Assorted calibrated pipettes. 6.1.3 Wash bottle - One piece stem, Teflon FEP bottle with Tefzel ETFE screw closure, 125-mL capacity.

6.2 SAMPLE PROCESSING EQUIPMEN1 6.2.1 Balance 0.1 mg.

-

Analytical, capable o f accurately weighing to

6.2.2 Hot Plate - (Corning PClOO or equivalent). hot plate will aid in sample digestion.

An oscillating

6.3 TISSUE DISSECTING EQUIPMENT 6.3.1. Dissecting Board: Polyethylene or other inert, nonmetallic material, any non-wetting, easy-to-clean or disposable surface is suitable. Adhesive backed Teflon or plastic film may be convenient to use.

6.3.2 forceps: Plastic, Teflon or Teflon coated.

28


6.3.3 S u r g i c a l Blades: D i s p o s a b l e s t a i n l e s s s t e e l w i t h s t a i n l e s s s t e e l o r p l a s t i c h a n d l e ( S e c t . 4.1). 6.3.4 S c i s s o r s :

Stainless steel

6.3.5 P l a s t i c bags w i t h w a t e r t i g h t s e a l , m e t a l f r e e . 6.3.6 Label tape:

Self-adhesive, v i n y l coated marking tape, s o l v e n t r e s i s t a n t , u s a b l e f o r temperatures f r o m t121OC t o -23OC.

6.3.7 P o l y v i n y l c h l o r i d e o r r u b b e r g l o v e s , t a l c - f r e e . 7.

REAGENTS AND CONSUMABLE HATERIALS

7.1

Reagents may c o n t a i n e l e m e n t a l i m p u r i t i e s w h i c h m i g h t a f f e c t a n a l y t i c a l d a t a . H i g h - p u r i t y r e a g e n t s s h o u l d be used whenever p o s s i b l e . A l l a c i d s used f o r t h i s method must be o f u l t r a h i g h p u r i t y grade.

7.1.1

N i t r i c acid, concentrated (sp.gr.

7.1.2

Hydrochloric acid, concentrated (sp.gr.

7.1.3

Hydrogen p e r o x i d e (30%)

1.41). 1.19).

7.2 WATER - F o r a l l sample p r e p a r a t i o n and d i l u t i o n s , ASTM t y p e I w a t e r (ASTM D1193) i s r e q u i r e d . S u i t a b l e w a t e r may be p r e p a r e d b y p a s s i n g d i s t i l l e d w a t e r t h r o u g h a mixed bed o f a n i o n and c a t i o n exchange resins. 8.

SAMPLE COLLECTION, PRESERVATION AND STORAGE

8.1

A p p r o p r i a t e i n d i v i d u a l t i s s u e samples s h o u l d bf t a k e n soon a f t e r If dissection o f c o l l e c t i o n and must be t a k e n p r i o r t o f r e e z i n g t h e t i s s u e cannot be performed i m m e d i a t e l y a f t e r c o l l e c t i o n , i t s h o u l d be p l a c e d i n a p l a s t i c bag (Sect. 6.3.5), s e a l e d and p l a c e d on i c e o r r e f r i g e r a t e d a t a p p r o x i m a t e l y 4 ° C .

8.2

P r i o r t o d i s s e c t i o n , t h e t i s s u e s h o u l d be r i n s e d w i t h m e t a l - f r e e w a t e r and b l o t t e d d r y . D i s s e c t i o n s h o u l d be p e r f o r m e d w i t h i n 24 hours o f c o l l e c t i o n . Each i n d i v i d u a l t i s s u e sample s h o u l d a l s o be r i n s e d w i t h m e t a l - f r e e w a t e r , b l o t t e d dry, and f r o z e n a t 50 mg/kg should be treated in a similar manner. Also, the extraction of tin from solid samples should be prepared again using aliquots < 1 g when determined sample concentrations exceed 1%. 1.8

The total recoverable sample digestion procedure given in this method will solubilize and hold in solution only minimal concentrations o f barium in the presence of free sulfate. For the analysis of barium in samples having varying and unknown concentrations of sulfate, analysis should be completed as soon as possible after sample preparation.

1.9

The total recoverable sample digestion procedure given in this method is not suitable for the determination of volatile organo-mercury compounds. However, if digestion is not required (turbidity < 1 NTU), the combined concentrations of inorganic and organo-mercury in solution can be determined by "direct analysis" pneumatic nebulization provided the sample solution is adjusted to contain the same mixed acid (HNO, t HC1) matrix as the total recoverable calibration standards and blank solutions.

1.10 Detection limits and linear ranges for the elements will vary with the wavelength selected, the spectrometer, and the matrices. Table 1 provides estimated instrument detection limits for the listed wavelengths.' However, actual method detection 1 imits and 1 inear working ranges will be dependent on the sample matrix, instrumentation, and selected operating conditions. 1.11 Users of the method data should state the data-quality ohjectives

prior to analysis. Users of the method must document and have on file the required initial demonstration performance data described in Section 9.2 prior to using the method for analysis. 2.0

SUMMARY OF METHOD 2.1

An aliquot of a well mixed, homogeneous aqueous or solid sample is accurately weighed or measured for sample processing. For total recoverable analysis of a solid or an aqueous sample containing undissolved material, analytes are first solubilized by gentle refluxing with nitric and hydrochloric acids. Aft,er cooling, the sample is made up to volume, is mixed and centrifuged or allowed to Revision 4.4 Hay 1994

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settle overnight prior to analysis. For the determination of dissolved analytes in a filtered aqueous sample aliquot, or for the "direct analysis" total recoverable determination of analytes in drinking water where sample turbidity is < 1 NTU, the sample is made ready for analysis by the appropriate addition of nitric acid, and then diluted to a predetermined volume and mixed before analysis. 2.2 The analysis described in this method involves multielemental determinations by ICP-AES using sequential or simultaneous instruments. The instruments measure characteristic atomic-line emission spectra by optical spectrometry. Samples are nebulized and the resulting aerosol is transported to the plasma torch. Element specific emission spectra are produced by a radio-frequency inductively coupled plasma. The spectra are dispersed by a grating spectrometer, and the intensities of the line spectra are monitored at specific wavelengths by a photosensitive device. Photocurrents from the photosensitive device are processed and controlled by a computer system. A background correction technique is required to compensate for variable background contribution to the determination o f the analytes. Background must be measured adjacent to the analyte wavelength during analysis. Various interferences must be considered and addressed appropriately as discussed in Sections 4, 7, 9, 10, and 11. 3.0

DEFINITIONS 3.1

Calibration Blank - A volume of reagent water acidified with the same acid matrix as in the calibration standards. The calibration blank is a zero standard and i s used to calibrate the ICP instrument (Sect. 7.10.1).

3.2 Calibration Standard (CAL) - A solution prepared from the dilution o f stock standard solutions. The CAL solutions are used to calibrate the instrument response with respect to analyte concentration (Sect. 7 . 9 ) . 3.3

Dissolved Analyte - The concentration of analyte in an aqueous sample that will pass through a 0.45-pm membrane filter assembly prior to sample acidification (Sect. 11.1).

3.4

Field Reagent Blank (FRB) - An aliquot of reagent water or other blank matrix that is placed in a sample container in the laboratory and treated as a sample in all respects, including shipment to the sampling site, exposure to the sampling site conditions, storage, preservation, and all analytical procedures. The purpose of the FRB is to determine if method analytes or other interferences are present in the field environment (Sect 8.5).

3.5 Instrument Detection Limit ( I D L ) - The concentration equivalent to the analyte signal which is equal to three times the standard deviation of a series of ten replicate measurements of the calibration blank signal at the same wavelength (Table 1.). 3.6

Instrument Performance Check (IPC) Solution - A solution of method analytes, used to evaluate the performance of the instrument system Revision 4.4 Hay 1994

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Methods for the Determination w i t h r e s p e c t t o a d e f i n e d set. o f method c r i t e r i a ( S e c t s . 9.3.4).

7.11 &

3.7

I n t e r n a l Standard - Pure a n a l y t e ( s ) added t o a sample, e x t r a c t , o r s t a n d a r d s o l u t i o n i n known amount(s) and used t o measure t h e r e l a t i v e responses o f o t h e r method a n a l y t e s t h a t a r e components o f t h e same sample o r s o l u t i o n . The i n t e r n a l s t a n d a r d must be an a n a l y t e t h a t i s n o t a sample component ( S e c t . 1 1 . 5 ) .

3.8

L a b o r a t o r y D u p l i c a t e s (LD1 and LD2) - Two a l i q u o t s o f t h e same sample t a k e n i n t h e l a b o r a t o r y and analyzed s e p a r a t e l y w i t h i d e n t i c a l procedures. Analyses o f LD1 and LO2 i n d i c a t e s p r e c i s i o n a s s o c i a t e d w i t h l a b o r a t o r y procedures, b u t n o t w i t h sample c o l l e c t i o n , p r e s e r v a t i o n , o r s t o r a g e procedures.

3.9

L a b o r a t o r y F o r t i f i e d B l a n k (LFB) - An a l i q u o t o f LRB t o which known q u a n t i t i e s of t h e method a n a l y t e s a r e added i n t h e l a b o r a t o r y . The LFB i s analyzed e x a c t l y l i k e a sample, and i t s purpose i s t o d e t e r m i n e whether t h e methodology i s i n c o n t r o l and whether t h e l a b o r a t o r y i s capable o f making a c c u r a t e and p r e c i s e measurements ( S e c t s . 7 . 1 0 . 3 & 9.3.2).

3 . 1 0 L a b o r a t o r y F o r t i f i e d Sample M a t r i x (LFM) - An a l i q u o t o f an environmental sample t o which known q u a n t i t i e s o f t h e method a n a l y t e s The LFM i s a n a l y z e d e x a c t l y l i k e a a r e added i n t h e l a b o r a t o r y . sample, and i t s purpose i s t o d e t e r m i n e whether t h e sample m a t r i x contributes bias t o the analytical results. The background c o n c e n t r a t i o n s o f t h e a n a l y t e s i n t h e sample m a t r i x must be determined i n a separate a l i q u o t and t h e measured v a l u e s i n t h e LFM c o r r e c t e d f o r background c o n c e n t r a t i o n s ( S e c t . 9 . 4 ) .

3.11 L a b o r a t o r y Reagent B l a n k (LRB) - An a l i q u o t o f r e a g e n t w a t e r o r o t h e r b l a n k m a t r i c e s t h a t a r e t r e a t e d e x a c t l y as a sample i n c l u d i n g exposure t o a17 glassware, equipment, s o l v e n t s , r e a g e n t s , and i n t e r n a l standards t h a t a r e used w i t h o t h e r samples. The LRB i s used t o d e t e r m i n e i f method a n a l y t e s o r o t h e r i n t e r f e r e n c e s a r e p r e s e n t i n t h e l a b o r a t o r y environment, r e a g e n t s , o r apparatus ( S e c t s . 7 . 1 0 . 2 & 9.3.1).

3.12 L i n e a r Dynamic Range (LDR) - The c o n c e n t r a t i o n range o v e r which t h e i n s t r u m e n t response t o an a n a l y t e i s l i n e a r ( S e c t . 9 . 2 . 2 ) .

3.13 Method D e t e c t i o n L i m i t (MDL) - The minimum c o n c e n t r a t i o n o f an a n a l y t e t h a t can be i d e n t i f i e d , measured, and r e p o r t e d w i t h 99% c o n f i d e n c e t h a t t h e a n a l y t e c o n c e n t r a t i o n i s g r e a t e r t h a n z e r o ( S e c t . 9.2.4 and Table 4.).

3 . 1 4 Plasma S o l u t i o n - A s o l u t i o n t h a t i s used t o d e t e r m i n e t h e oDtimum h e i g h t above t h e work c o i l f o r v i e w i n g t h e plasma ( S e c t s . 7.15 & 10.2.3). 3 . 1 5 Q u a l i t y C o n t r o l Sample (QCS) - A s o l u t i o n o f method a n a l y t e s o f known c o n c e n t r a t i o n s which i s used t o f o r t i f y an a l i q u o t o f L R B o r sample m a t r i x . The QCS i s o b t a i n e d f r o m a source e x t e r n a l t o t h e l a b o r a t o r y R e v i s i o n 4.4 May 1994

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and d i f f e r e n t f r o m t h e source o f c a l i b r a t i o n s t a n d a r d s . I t i s used t o check e i t h e r l a b o r a t o r y o r i n s t r u m e n t performance ( S e c t s . 7.12 & 9.2.3). 3.16 S o l i d Sample - F o r t h e purpose o f t h i s method, a sample t a k e n from m a t e r i a l c l a s s i f i e d as e i t h e r s o i l , sediment o r s l u d g e . 3.17 S p e c t r a l I n t e r f e r e n c e Check (SIC) S o l u t i o n - A s o l u t i o n o f s e l e c t e d method a n a l y t e s of h i g h e r c o n c e n t r a t i o n s which i s used t o e v a l u a t e t h e p r o c e d u r a l r o u t i n e f o r c o r r e c t i n g known i n t e r e l e m e n t s p e c t r a l i n t e r f e r e n c e s w i t h r e s p e c t t o a d e f i n e d s e t o f method c r i t e r i a ( S e c t s . 7.13, 7.14 & 9 . 3 . 5 ) . 3.18 Standard A d d i t i o n - The a d d i t i o n o f a known amount o f a n a l y t e t o t h e sample i n o r d e r t o d e t e r m i n e t h e r e l a t i v e response o f t h e d e t e c t o r t o an a n a l y t e w i t h i n t h e sample m a t r i x . The r e l a t i v e response i s t h e n used t o assess e i t h e r an o p e r a t i v e m a t r i x e f f e c t o r t h e sample a n a l y t e c o n c e n t r a t i o n ( S e c t s . 9.5.1 & 1 1 . 5 ) . 3.19 S t o c k Standard S o l u t i o n - A c o n c e n t r a t e d s o l u t i o n c o n t a i n i n g one o r more method a n a l y t e s p r e p a r e d i n t h e l a b o r a t o r y u s i n g assayed r e f e r e n c e m a t e r i a l s o r purchased f r o m a r e p u t a b l e commercial source (Sect. 7.8). 3.20 T o t a l Recoverable A n a l y t e - The c a n c e n t r a t i o n o f a n a l y t e determined e i t h e r by “ d i r e c t a n a l y s i s ” o f an u n f i l t e r e d a c i d p r e s e r v e d d r i n k i n g w a t e r sample w i t h t u r b i d i t y o f < 1 NTU ( S e c t . 11.2.1), o r by a n a l y s i s o f t h e s o l u t i o n e x t r a c t o f a s o l i d sample o r an u n f i l t e r e d aqueous sample f o l l o w i n g d i g e s t i o n by r e f l u x i n g w i t h h o t d i l u t e m i n e r a l a c i d ( s ) as s p e c i f i e d i n t h e method ( S e c t s . 11.2 & 1 1 . 3 ) . 3.21 Water Sample - F o r t h e purpose o f t h i s method, a sample t a k e n f r o m one o f t h e f o l l o w i n g sources: d r i n k i n g , s u r f a c e , ground, storm r u n o f f , i n d u s t r i a l o r domestic wastewater.

4.0

INTERFERENCES 4.1

S p e c t r a l i n t e r f e r e n c e s a r e caused by background e m i s s i o n from c o n t i n u o u s o r r e c o m b i n a t i o n phenomena, s t r a y l i g h t f r o m t h e l i n e e m i s s i o n o f h i g h c o n c e n t r a t i o n elements, o v e r l a p o f a s p e c t r a l l i n e f r o m a n o t h e r element, o r u n r e s o l v e d over1 ap o f m o l e c u l a r band s p e c t r a . 4.1.1

Background e m i s s i o n and s t r a y l i g h t can u s u a l l y be compensated f o r by s u b t r a c t i n g t h e background e m i s s i o n determined by measurement(s) a d j a c e n t t o t h e a n a l y t e wavelength peak. S p e c t r a l scans o f samples o r s i n g l e element s o l u t i o n s i n t h e a n a l y t e r e g i o n s may i n d i c a t e n o t o n l y when a l t e r n a t e wavelengths a r e d e s i r a b l e because o f severe s p e c t r a l i n t e r f e r e n c e , b u t a l s o w i l l show whether t h e most a p p r o p r i a t e e s t i m a t e o f t h e background e m i s s i o n i s p r o v i d e d by an i n t e r p o l a t i o n f r o m measurements on b o t h s i d e s o f t h e wavelength peak o r by t h e measured e m i s s i o n on one s i d e o r t h e other. The l o c a t i o n ( s ) s e l e c t e d f o r t h e measurement o f background i n t e n s i t y w i l l be determined by t h e c o m p l e x i t y o f R e v i s i o n 4 . 4 May1994

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the spectrum adjacent to the wavelength peak. The location(s) used for routine measurement must be free of off-line spectral interference (interelement or molecular) or adequately corrected to reflect the same change in background intensity as occurs at the wavelength peak. 4.1.2

Spectral overlaps may be avoided by using an alternate wavelength or can be compensated for by equations that correct for interelement contributions, which involves measuring the interfering elements. Some potential on-line spectral interferences observed for the recommended wavelengths are given in Table 2. When operative and uncorrected, these interferences will produce false-positive determinations and be reported as analyte concentrations. The interferences listed are only those that occur between method analytes. Only interferences of a direct overlap nature that were observed with a single instrument having a working resolution o f 0.035 nm are listed. More extensive information on interferant effects at variou: wavelengths and resolutions is available in Boumans’ Tables. Users may apply interelement correction factors determined on their instruments within tested concentration ranges to compensate (off-line or online) for the effects of interfering elements.

4.1.3

When interelement corrections are applied, there is a need to verify their accuracy by analyzing spectral interference check solutions as described in Section 7 . 1 3 . Interelement corrections will vary for the same emission line among instruments because of differences in resolution, as determined by the grating plus the entrance and exit slit widths, and by the order of dispersion. Interelement corrections will also vary depending upon the choice of background correction points. Selecting a background correction point where an interfering emission line may appear should be avoided when practical. Interelement corrections that constitute a major portion of an emission signal may not yield accurate data. Users should not forget that some samples may contain uncommon elements that could contribute spectral interferences .7*8

4.1.4

The interference effects must be evaluated for each individual instrument whether configured as a sequential or simultaneous instrument. For each instrument, intensities will vary not only with optical resolution but also with operating conditions (such as power, viewing height and argon flow rate). When using the recommended wavelengths given in Table 1 , the analyst is required t o determine and document for each wavelength the effect from the known interferences given in Table 2 , and to utilize a computer routine for their automatic correction on all analyses. To determine the appropriate location for off-1 ine background correction, the user must scan the area on either side adjacent to the wavelength and record the apparent emission intensity from all other method analytes. This spectral information must be documented and Revision 4.4 Hay 1994

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kept on file. Ihe location selected for background correction must be either free of off-line interelement spectral int.erfrrc!ncc> or a computer routine must be used for their aut.omat.ic corri?(.t.ion on all determinations. I f a wavelength other than t ti(! recoinmended wavelength is used, the user must det.ermirre and document both the on-1 ine and off-1 ine spectral int.erferen(-r Pffect from all method analytes and provide for their dutoinnt.ic correction on all analyses. Tests to determine t h e spectral interference must be done using analyte concentrations that will adequately describe the interference. Normally, 100 mg/L single element solutions are sufficient, however, for analytes such as iron that may be found at high concentration a more appropriate test would be to use a concentration near the upper LDR limit. See Section 10.4 for required spectral interference test criteria. 4.1.5

4.2

When interelement corrections are not used, either on-going S I C solutions (Sect. 7.14) must be analyzed to verify the absence o f interel ement spectral interference or a computer software routine must be employed for comparing the determinative data to limits files for notifying the analyst when an interfering element is detected in the sample at a concentration that will produce either an apparent false positive concentration, > the analyte I D L , or false negative analyte concentration, < the 99% lower control limit of the calibration blank. When the interference accounts for 10% or more o f the analyte concentration, either an alternate wavelength free of interference or another approved test procedure must be used to complete the analysis. For example, the copper peak at 213.853 nm could be mistaken for the zinc peak at 213.856 nm in solutions with high copper and low zinc concentrations. For this example, a spectral scan in the 213.8-nm region would not reveal the misidentification because a single peak near the zinc location would be observed. The possibility of this misidentification of copper for the zinc peak at 213.856 nm can be identified by measuring the copper at another emission line, e.g. 324.754 nm. Users should be aware that, depending upon the instrumental resolution, a1 ternate wavelengths with adequate sensitivity and freedom from interference may not be available for all matrices. In these circumstances the analyte must be determined using another approved test procedure.

Physical interferences are effects associated with the sample nebulization and transport processes. Changes in viscosity and surface tension can cause significant inaccuracies, especially in samples containing high dissolved solids or high acid concentrations. If physical interferences are present, they must be reduced by such means as a high-solids nebulizer, diluting the sample, using a peristaltic pump, or using an appropriate internal standard element. Another problem that can occur with high dissolved solids is salt buildup at the tip of the nebulizer, which affects aerosol flow rate and causes instrumental drift. This problem can be controlled by a high-solids nebulizer, wetting the argon prior to nebulization, using Revision 4 . 4 Hay 1994

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Methods for the Determination a tip washer, or diluting the sample. Also, it has been reported that better control of the argon flow rates, especially for the nebulizer, improves instrument stab'rlityand precision; this is accomplished with the use of mass flow controllers.

5.0

4.3

Chemical interferences include molecular-compound formation, ionization effects, and solute-vaporization effects. Normally, these effects are not significant with the ICP-AES technique. If observed, they can be minimized by careful selection of operating conditions (such as incident power and observation height), by buffering of the sample, by matrix matching, and by standard-addition procedures. Chemical interferences are highly dependent on matrix type and the specific analyte element.

4.4

Memory interferences result when analytes in a previous sample contribute to the signals measured in a new sample. Memory effects can result from sample deposition on the uptake tubing to the nebulizer, and from the buildup of sample material in the plasma torch and spray chamber. The site where these effects occur is dependent on the element and can be minimized by flushing the system with a rinse blank between samples (Sect. 7 . 1 0 . 4 ) . The possibility of memory interferences should be recognized within an analytical run and suitable rinse times should be used to reduce them. The rinse times necessary for a particular element must be estimated prior to analysis. This may be achieved by aspirating a standard containing elements corresponding to either their LDR or a concentration ten times those usually encountered. The aspiration time should be the same as a normal sample analysis period, followed by analysis of the rinse blank at designated intervals. The length of time required to reduce analyte signals to within a factor of two of the method detection limit, should be noted. Until the required rinse time is established, this method requires a rinse period of at least 60 sec between samples and standards. If a memory interference is suspected, the sample must be re-analyzed after a long rinse period.

SAFETY

5.1

The toxicity or carcinogenicity of each reagent used in this method have not been fully established. Each chemical should be regarded as a potential health hazard and exposure to these compounds should be as low as reasonably achievable. Each laboratory is responsible for maintaining a current awareness file of OSHA regulations regard?-y9 the safe handling of the chemicals specified in this method. A reference file of material data handling sheets should also be made available to all personnel involved in the chemical analysis. Specifically, concentrated nitric and hydrochloric acids present various hazards and are moderately toxic and extremely irritating to skin and mucus membranes. Use these reagents in a fume hood whenever possible and if eye or skin contact occurs, flush with large volumes of water. Always wear safety glasses or a shield for eye protection, protective clothing and observe proper mixing when working with these reagents.

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5.2

The a c i d i f i c a t i o n o f samples c o n t a i n i n g r e a c t i v e m a t e r i a l s may r e s u l t i n t h e r e l e a s e o f t o x i c gases, such as cyanides o r s u l f i d e s . A c i d i f i c a t i o n o f samples s h o u l d be done i n a fume hood.

5.3


5.4

The i n d u c t i v e l y c o u p l e d plasma s h o u l d o n l y be viewed w i t h p r o p e r eye p r o t e c t i o n from the u l t r a v i o l e t emissions.

5.5

I t i s t h e r e s p o n s i b i l i t y o f t h e u s e r o f t h i s method t o comply w i t h r e l e v a n t d i s p o s a l and waste r e g u l a t i o n s . F o r guidance see S e c t i o n s 14.0 and 15.0.

EQUIPMENT AND 6.1

SUPPLIES

I n d u c t i v e l y c o u p l e d plasma e m i s s i o n s p e c t r o m e t e r : 6.1.1

C o m p u t e r - c o n t r o l l e d e m i s s i o n spectrometer w i t h backgroundc o r r e c t i o n c a p a b i l i t y . The spectrometer must be capable o f meeting and complying w i t h t h e r e q u i r e m e n t s d e s c r i b e d and r e f e r e n c e d i n S e c t i o n 2.2.

6.1.2

Radio-frequency g e n e r a t o r c o m p l i a n t w i t h FCC r e g u l a t i o n s .

6.1.3

Argon gas s u p p l y - H i g h p u r i t y grade (99.99%). When analyses a r e conducted f r e q u e n t l y , l i q u i d argon i s more economical and r e q u i r e s l e s s f r e q u e n t replacement o f t a n k s t h a n compressed argon i n c o n v e n t i o n a l c y l i n d e r s .

6.1.4

A v a r i a b l e speed p e r i s t a l t i c pump i s r e q u i r e d t o d e l i v e r b o t h s t a n d a r d and sample s o l u t i o n s t o t h e n e b u l i z e r .

6.1.5

( o p t i o n a l ) Mass f l o w c o n t r o l l e r s t o r e g u l a t e t h e argon f l o w r a t e s , e s p e c i a l l y t h e a e r o s o l t r a n s p o r t gas, a r e h i g h l y recommended. T h e i r use w i l l p r o v i d e more e x a c t i n g c o n t r o l o f r e p r o d u c i b l e p l asma c o n d i t i o n s .

6.2

A n a l y t i c a l balance, w i t h c a p a b i l i t y t o measure t o 0.1 mg, f o r use i n w e i g h i n g s o l i d s , f o r p r e p a r i n g standards, and f o r d e t e r m i n i n g dissolved solids i n digests o r extracts.

6.3

A temperature adjustable t e m p e r a t u r e o f 95OC.

6.4

A t e m p e r a t u r e a d j u s t a b l e b l o c k d i g e s t e r capable o f (optional) m a i n t a i n i n g a t e m p e r a t u r e o f 95OC and equipped w i t h 250-mL c o n s t r i c t e d d i g e s t i o n tubes.

6.5

( o p t i o n a l ) A s t e e l c a b i n e t c e n t r i f u g e w i t h g u a r d bowl, e l e c t r i c t i m e r and b r a k e .

hot

plate

capable

of

maintaining

a

R e v i s i o n 4 . 4 May 1994

42


6.6 A gravity convection drying oven with thermostatic control capable o f maintaining 180°C f 5OC.

6.7 (optional) An air displacement pipetter capable of delivering volumes ranging from 0.1 to 2500 pL with an assortment o f high quality disposable pipet tips. 6.8 Mortar and pestle, ceramic or nonmetallic material.

6.9 Polypropylene sieve, 5-mesh ( 4 mm opening). 6.10 Labware - For determination of trace levels of elements, contamination and loss are of prime consideration. Potential contamination sources include improperly cleaned 1 aboratory apparatus and general contamination within the laboratory environment from dust, etc. A clean 1 aboratory work area designated for trace element sample handling must be used. Sample containers can introduce positive and negative errors in the determination of trace elements by (1) contributing contaminants through surface desorption or leaching, (2) depleting element concentrations through adsorption processes. All reusable labware (glass, quartz, polyethylene, PTFE, FEP, etc.) should be sufficiently clean for the task objectives. Several procedures found to provide clean labware include washing with a detergent solution, rinsing with tap water, soaking for 4 h or more in 20% (v/v) nitric acid or a mixture of HNO, and HC1 (1+2+9), rinsing with reagent water and storing clean.*13 Chromic acid cleaning solutions must be avoided because chromium is an analyte. 6.10.1 Glassware - Volumetric flasks, graduated cylinders, funnels and centrifuge tubes (glass and/or metal-free plastic). 6.10.2 Assorted calibrated pipettes.

6.10.3 Conical Phillips beakers (Corning 1080-250 or equivalent), 250-mL with 50-mm watch glasses. 6.10.4 Griffin beakers, 250-mL with 75-mm watch (optional) 75-mm ribbed watch glasses.

glasses

and

6.10.5 (optional) PTFE and/or quartz Griffin beakers, 250-mL with PTFE covers.

6.10.6 Evaporating dishes or high-form crucibles, porcelain, 100 mL capaci ty . 6.10.7 Narrow-mouth storage bottles, FEP (fluorinated ethylene propylene) with screw closure, 125-mL to l-L capacities. 6.10.8 One-piece stem FEP wash bottle with screw closure, 125-mL capacity.

Revision 4.4 Hay 1994

Metals 7.0

43

REAGENTS AND STANDARDS

7.1 Reagents may contain elemental

impurities which might affect analytical data. Only high-purity reagents that conform to the American Chemical Society specifications should be used whenever possible. If the purity of a reagent is in question, analyze for contamination. All acids used for this method must be o f ultra highpurity grade or equivalent. Suitable acids are available from a number o f manufacturers. Redistilled acids prepared by sub-boil ing di st i 1 1 at ion are acceptable.

7.2 Hydrochloric acid, concentrated (sp.gr. 1.19) - HC1. 7.2.1

Hydrochloric acid (ltl) - Add 500 mL concentrated HC1 to 400 mL reagent water and dilute to 1 L.

7.2.2

Hydrochloric acid (lt4) - Add 200 m L concentrated HC1 to 400 mL reagent water and dilute to 1 L.

7.2.3

Hydrochloric acid (1t20) mL reagent water.

-

Add 10 mL concentrated HC1 to 200

7.3 Nitric acid, concentrated (sp.gr. 1.41)

-

HNO,.

7.3.1

Nitric acid (1t1) - Add 500 mL concentrated HNO, to 400 mL reagent water and dilute to 1 L .

7.3.2

Nitric acid (1t2) reagent water.

7.3.3

Nitric acid (1t5) - Add 50 mL concentrated HNO, to 250 mL reagent water.

7.3.4

Nitric acid (1t9)

-

-

Add 100 mL concentrated HNO, to 200 mL

Add 10 mL concentrated HNO, to 90 mL

reagent water.

7.4 Reagent water. A11,references to water in this method refer to ASTM Type I grade water.

7.5 Ammonium hydroxide, concentrated (sp. gr. 0.902). 7.6 Tartaric acid, ACS reagent grade.

7.7 Hydrogen peroxide, 50%, stabilized certified reagent grade. 7.8 Standard Stock Solutions - Stock standards may be purchased or prepared from ultra-high purity grade chemicals (99.99 to 99.999% All compounds must be dried for 1 h at 105"C, unless pure). otherwise specified. It is recommended that stock solutions be stored in FEP bottles. Replace stock standards when succeeding dilutions for preparation of calibration standards cannot be verified. CAUTION:

Many of these chemicals are extremely toxic if inhaled or swallowed (Sect. 5.1). Wash hands thoroughly after handling. Revision 4.4 Hay 1994

44

Methods for the Determination T y p i c a l s t o c k s o l u t i o n p r e p a r a t i o n procedures f o l l o w f o r l - L q u a n t i t i e s , b u t f o r t h e purpose o f p o l l u t i o n p r e v e n t i o n , t h e a n a l y s t i s encouraged t o p r e p a r e s m a l l e r q u a n t i t i e s when p o s s i b l e . C o n c e n t r a t i o n s a r e c a l c u l a t e d based upon t h e w e i g h t o f t h e p u r e element o r upon t h e w e i g h t o f t h e compound m u l t i p l i e d b y t h e f r a c t i o n o f t h e a n a l y t e i n t h e compound. From p u r e element , w e i g h t (mg ) Concentration = volume (L) From p u r e compound, w e i g h t (mg) x g r a v i m e t r i c f a c t o r Concentration = volume ( L ) where : g r a v i m e t r i c f a c t o r = the weight f r a c t i o n o f t h e gnalyte i n the compound. 7.8.1

Aluminum s o l u t i o n , s t o c k , 1 mL = 1000 p g A l : D i s s o l v e 1.000 g o f aluminum m e t a l , weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n an a c i d m i x t u r e o f 4.0 mL o f ( l t l ) HC1 and 1.0 mL o f c o n c e n t r a t e d HNO, i n a beaker. Warm beaker slowly t o e f f e c t solution. When d i s s o l u t i o n i s complete, t r a n s f e r s o l u t i o n q u a n t i t a t i v e l y t o a l - L f l a s k , add an a d d i t i o n a l 10.0 mL o f ( l t l ) HC1 and d i l u t e t o volume w i t h reagent water.

7.8.2

Antimony s o l u t i o n , s t o c k , 1 mL = 1000 p g Sb: D i s s o l v e 1.000 g o f antimony powder, weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 20.0 rnL ( l t l ) HNO, and 10.0 mL c o n c e n t r a t e d HC1. Add 100 mL r e a g e n t w a t e r and 1.50 g t a r t a r i c acid. Warm s o l u t i o n s l i g h t l y t o e f f e c t complete d i s s o l u t i o n . Cool s o l u t i o n and add r e a g e n t w a t e r t o volume i n a l - L volumetric flask.

7.8.3

A r s e n i c s o l u t i o n , s t o c k , 1 mL = 1000 p g As: D i s s o l v e 1.320 g o f As,O, ( A s f r a c t i o n = 0.7574), weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 100 mL o f r e a g e n t w a t e r c o n t a i n i n g 10.0 mL c o n c e n t r a t e d NH OH. Warm t h e s o l u t i o n g e n t l y t o e f f e c t d i s s o l u t i o n . A c i d i t y t h e s o l u t i o n w i t h 20.0 mL c o n c e n t r a t e d HNO, and d i l u t e t o volume i n a l - L v o l u m e t r i c f l a s k w i t h reagent water.

7.8.4

Barium s o l u t i o n , s t o c k , 1 mL = 1000 pg Ba: D i s s o l v e 1.437 g BaCO, (Ba f r a c t i o n = 0.6960), weighed a c c u r a t e l y t o a t l e a s t R e v i s i o n 4.4 May 1994

Metals

45

f o u r s i g n i f i c a n t f i g u r e s , i n 150 mL ( 1 t 2 ) HNO, w i t h h e a t i n g and s t i r r i n g t o degas and d i s s o l v e compound. L e t solution c o o l and d i l u t e w i t h r e a g e n t w a t e r i n 1-L v o l u m e t r i c f l a s k . 7.8.5

B e r y l l i u m s o l u t i o n , s t o c k , 1 mL = 1000 pg Be: DO NOT DRY. D i s s o l v e 19.66 g BeS04*4H,0 (Be f r a c t i o n = 0.0509), weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n reagent water, add 10.0 mL Concentrated HNO,, and d i l u t e t o volume i n a 1-L v o l u m e t r i c f l a s k w i t h r e a g e n t w a t e r .

7.8.6

Boron s o l u t i o n , s t o c k , 1 mL = 1000 p g B: DO NOT DRY. D i s s o l v e 5.716 g anhydrous H BO ( B f r a c t i o n = 0.1749), weighed a c c u r a t e l y t o a t l e a s € Sour s i g n i f i c a n t f i g u r e s , i n reagent w a t e r and d i l u t e i n a 1-L v o l u m e t r i c f l a s k w i t h r e a g e n t w a t e r . T r a n s f e r i m m e d i a t e l y a f t e r m i x i n g t o a c l e a n FEP b o t t l e t o m i n i m i z e any l e a c h i n g o f boron f r o m t h e g l a s s v o l u m e t r i c c o n t a i n e r . Use o f a nonglass v o l u m e t r i c f l a s k i s recommended t o a v o i d boron c o n t a m i n a t i o n f r o m glassware.

7.8.7

Cadmium s o l u t i o n , s t o c k , 1 mL = 1000 p g Cd: D i s s o l v e 1.000 g Cd m e t a l , a c i d cleaned w i t h ( 1 t 9 ) HNO,, weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 50 mL ( l t l ) HNO w i t h h e a t i n g t o e f f e c t d i s s o l u t i o n . L e t s o l u t i o n c o o l and d i l u t e w i t h r e a g e n t w a t e r i n a 1-L v o l u m e t r i c f l a s k .

7.8.8

Calcium s o l u t i o n , s t o c k , 1 mL = 1000 p g Ca: Suspend 2.498 g CaCO (Ca f r a c t i o n = 0.4005), d r i e d a t 180°C f o r 1 h b e f o r e weighing, weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n r e a g e n t w a t e r and d i s s o l v e c a u t i o u s l y w i t h a minimum amount o f ( l t l ) HNO,. Add 10.0 mL c o n c e n t r a t e d HNO, and d i l u t e t o volume i n a 1-L v o l u m e t r i c f l a s k w i t h reagent water.

7.8.9

Cerium s o l u t i o n , s t o c k , 1 mL = 1000 pg Ce: S l u r r y 1.228 g CeO, (Ce f r a c t i o n = 0.8141), weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 100 mL c o n c e n t r a t e d HNO, and evaporate t o dryness. S l u r r y t h e r e s i d u e i n 20 mL H20, add 50 mL c o n c e n t r a t e d HNO,, w i t h h e a t and s t i r r i n g add 60 mL 50% HzOz d r o p w i s e i n 1 mL increments a l l o w i n g p e r i o d s o f s t i r r i n g B o i l o f f excess H202 b e f o r e between t h e 1 mL a d d i t i o n s . d i l u t i n g t o volume i n a I - L v o l u m e t r i c f l a s k w i t h r e a g e n t water.

7.8.10

Chromium s o l u t i o n , s t o c k , 1 mL = 1000 p g C r : D i s s o l v e 1.923 g CrO, ( C r f r a c t i o n = 0.5200), weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 120 mL ( 1 t 5 ) HNO,. When s o l u t i o n i s complete, d i l u t e t o volume i n a 1-L v o l u m e t r i c f l a s k w i t h reagent water.

7.8.11

C o b a l t s o l u t i o n , s t o c k , 1 mL = 1000 pg Co: D i s s o l v e 1.000 g Co m e t a l , a c i d cleaned w i t h ( 1 t 9 ) HNO,, weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 50.0 mL ( l t l ) HNO,. Let s o l u t i o n c o o l and d i l u t e t o volume i n a 1-L v o l u m e t r i c f l a s k w i t h reagent water. R e v i s i o n 4 . 4 May1994

46


Copper s o l u t i o n , s t o c k , 1 mL = 1000 p g Cu: D i s s o l v e 1.000 g Cu m e t a l , a c i d cleaned w i t h ( 1 t 9 ) HN03, weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , I n 50.0 mL ( l t l ) HNO, w i t h h e a t i n g t o e f f e c t d i s s o l u t i o n . L e t s o l u t i o n c o o l and d i l u t e i n a 1-L v o l u m e t r i c f l a s k w i t h r e a g e n t w a t e r .

7.8.13

I r o n s o l u t i o n , s t o c k , 1 mL = 1000 p g Fe: D i s s o l v e 1.000 g Fe m e t a l , a c i d cleaned w i t h ( l t l ) HC1, weighed a c c u r a t e l y t o f o u r s i g n i f i c a n t f i g u r e s , i n 100 mL ( l t l ) HC1 w i t h h e a t i n g t o e f f e c t d i s s o l u t i o n . L e t s o l u t i o n c o o l and d i l u t e w i t h r e a g e n t w a t e r i n a 1-L v o l u m e t r i c f l a s k .

7.8.14

Lead s o l u t i o n , s t o c k , 1 mL = 1000 p g Pb: D i s s o l v e 1.599 g Pb(N0,) (Pb f r a c t i o n = 0.6256), weighed a c c u r a t e l y t o a t l e a s t t o u r s i g n i f i c a n t f i g u r e s , i n a minimum amount o f ( 1 t 1 ) Add 20.0 mL ( l t l ) HNO, and d i l u t e t o volume i n a l - L HNO,. volumetric f l a s k w i t h reagent water.

7.8.15

L i t h i u m s o l u t i o n , s t o c k , 1 mL = 1000 p g L i : D i s s o l v e 5.324 g Li,CO, ( L i f r a c t i o n = 0.1878), weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n a minimum amount o f ( l t l ) HC1 and d i l u t e t o volume i n a l - L v o l u m e t r i c f l a s k w i t h r e a g e n t w a t e r .

7.8.16

Magnesium s o l u t i o n , s t o c k , 1 mL = 1000 p g Mg: D i s s o l v e 1.000 g c l e a n l y p o l i s h e d Mg r i b b o n , a c c u r a t e l y weighed t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n s l o w l y added 5.0 mL ( l t l ) HC1 (CAUTION: r e a c t i o n i s v i g o r o u s ) . Add 20.0 mL ( l t l ) HNO, and d i l u t e t o volume i n a l - L v o l u m e t r i c f l a s k w i t h r e a g e n t w a t e r .

7.8.17

Manganese s o l u t i o n , s t o c k , 1 mL = 1000 p g Mn: D i s s o l v e 1.000 g o f manganese m e t a l , weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 50 mL ( l t l ) HNO, and d i l u t e t o volume i n a l - L volumetric f l a s k w i t h reagent water.

7.8.18

Mercury s o l u t i o n , s t o c k , 1 mL = 1000 p g Hg: DO NOT DRY. CAUTION: h i g h l y t o x i c element. D i s s o l v e 1.354 g HgC1, (Hg f r a c t i o n = 0.7388) i n r e a g e n t w a t e r . Add 50.0 mL c o n c e n t r a t e d HNO, and d i l u t e t o volume i n 1-L v o l u m e t r i c f l a s k w i t h r e a g e n t water.

7.8.19

Molybdenum s o l u t i o n , s t o c k , 1 mL = 1000 p g Mo: D i s s o l v e 1.500 g MOO, (Mo f r a c t i o n = 0.6666), weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n a m i x t u r e o f 100 mL r e a g e n t w a t e r and 10.0 mL c o n c e n t r a t e d NH,OH, h e a t i n g t o e f f e c t d i s s o l u t i o n . L e t s o l u t i o n c o o l and d i l u t e w i t h r e a g e n t w a t e r i n a l - L volumetric flask.

7.8.20

N i c k e l s o l u t i o n , s t o c k , 1 mL = 1000 p g N i : D i s s o l v e 1.000 g of n i c k e l m e t a l , weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 20.0 mL h o t c o n c e n t r a t e d HNO,, c o o l , and d i l u t e t o volume i n a l - L v o l u m e t r i c f l a s k w i t h r e a g e n t water.

R e v i s i o n 4.4 May 1994

Metals

47

7.8.21

Phosphorus s o l u t i o n , s t o c k , 1 mL = 1000 pg P : D i s s o l v e 3.745 g NH,H PO, ( P f r a c t i o n = 0 . 2 6 9 6 ) , weighed a c c u r a t e l y t o a t l e a s t t o u r s i g n i f i c a n t f i g u r e s , i n 200 mL r e a g e n t water and d i l u t e t o volume in a 1 - L v o l u m e t r i c f l a s k with r e a g e n t w a t e r .

7.8.22

Potassium s o l u t i o n , s t o c k , 1 rnL = 1000 pg K : D i s s o l v e 1.907 g KC1 ( K f r a c t i o n = 0.5244) d r i e d a t l l O " C , weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , in r e a g e n t w a t e r , add 20 mL ( 1 t 1 ) HC1 and d i l u t e t o volume i n a l-L volumetric f l a s k with reagent water.

7.8.23

Selenium s o l u t i o n , s t o c k , 1 mL = 1000 pg Se: D i s s o l v e 1.405 g SeO, (Se f r a c t i o n = 0 . 7 1 1 6 ) , weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 200 mL r e a g e n t water and d i l u t e t o volume i n a l - L v o l u m e t r i c f l a s k with r e a g e n t w a t e r .

7.8.24

S i l i c a s o l u t i o n , s t o c k , 1 mL = 1000 pg SiO : DO NOT DRY. D i s s o l v e 2.964 g (NH,),SiF6, weighed a c c u r a t e 5 y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 200 mL ( 1 t 2 0 ) HC1 with h e a t i n g a t 85°C t o e f f e c t d i s s o l u t i o n . Let s o l u t i o n cool and d i l u t e t o volume i n a l - L v o l u m e t r i c f l a s k with r e a g e n t w a t e r .

7.8.25

S i l v e r s o l u t i o n , s t o c k , 1 mL = 1000 pg Ag: D i s s o l v e 1.000 g Ag m e t a l , weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 80 mL ( 1 t 1 ) HNO, with h e a t i n g t o e f f e c t d i s s o l u t i o n . Let s o l u t i o n cool and d i l u t e with r e a g e n t water i n a l-L v o l u m e t r i c f l a s k . S t o r e s o l u t i o n i n amber b o t t l e o r wrap b o t t l e completely w i t h aluminum f o i l t o p r o t e c t s o l u t i o n from l i g h t .

7.8.26

Sodium s o l u t i o n , s t o c k , 1 mL = 1000 pg Na: D i s s o l v e 2.542 g NaCl (Na f r a c t i o n = 0.3934), weighed a c c u r a t e l y t o a t l e a s t four s i g n i f i c a n t figures, in reagent water. Add 10.0 mL c o n c e n t r a t e d HNO, and d i l u t e t o volume i n a l-L volumetric f l a s k with reagent water.

7.8.27

S t r o n t i u m s o l u t i o n , s t o c k , 1 mL = 1000 fig S r : D i s s o l v e 1.685 g SrCO, ( S r f r a c t i o n = 0.5935), weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 200 mL r e a g e n t w a t e r with dropwise a d d i t i o n o f 100 mL ( l t l ) HC1. D i l u t e t o volume i n a l - L volumetric f l a s k with reagent water.

7.8.28

Thallium s o l u t i o n , s t o c k , 1 mL = 1000 pg T1: D i s s o l v e 1.303 g TlNO, (T1 f r a c t i o n = 0 . 7 6 7 2 ) , weighed a c c u r a t e l y t o a t l e a s t four s i g n i f i c a n t figures, in reagent water. Add 1 0 . 0 mL c o n c e n t r a t e d HNO, and d i l u t e t o volume i n a l-L v o l u m e t r i c f l a s k with reagent water.

7.8.29

Tin s o l u t i o n , s t o c k , 1 mL = 1000 pg Sn: Dissolve 1.000 g Sn s h o t , weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n an a c i d mixture of 10.0 mL c o n c e n t r a t e d HC1 and 2 . 0 mL ( l t l ) HNO, with h e a t i n g t o e f f e c t d i s s o l u t i o n . Let s o l u t i o n c o o l , add 200 mL c o n c e n t r a t e d HC1, and d i l u t e t o volume in a l-L v o l u m e t r i c f l a s k w i t h r e a g e n t w a t e r . R e v i s i o n 4 . 4 May1994

48


Titanium solution, ctock, 1 mL = 1000 pg Ti: DO NOT DRY. (Ti fraction = 0.1629), Dissolve 6.138 g (Nli,),TiO(CZO ),*H,O weighed accurately t o a t least four significant figures, in 100 mL reagent water. Dilute to volume in a 1-L volumetric flask with reagent water.

7.8.31

Vanadium solution, stock, 1 mL = 1000 pg V : Dissolve 1.000 g V metal, acid cleaned with ( 1 t 9 ) HN03, weighed accurately to at least four significant figures, in 50 mL ( l t l ) HNO with heating to effect dissolution. Let solution cool and dilute with reagent water to volume in a l-L volumetric flask.

7.9

7.8.32

Yttrium solution, stock 1 mL = 1000 pg Y : Dissolve 1.270 g Y,O, (Y fraction = 0.7875), weighed accurately to at least heating to four significant figures, in 50 mL ( l t l ) HNO,, effect dissolution. Cool and dilute to volume in a l - L volumetric flask with reagent water.

7.8.33

Zinc solution, stock, 1 mL = 1000 pg Zn: Dissolve 1.000 g Zn metal, acid cleaned with ( 1 t 9 ) HNO,, weighed accurately to at least four significant figures, in 50 mL ( l t l ) HNO, .with heating to effect dissolution. Let solution cool and dilute with reagent water to volume in a l-L volumetric flask.

Mixed Calibration Standard Solutions - For the analysis of total recoverable digested samples prepare mixed calibration standard solutions (see Table 3 ) by combining appropriate volumes of the stock solutions in 500-mL volumetric flasks containing 20 mL ( l t l ) HNO, and 20 mL ( l t l ) HC1 and dilute to volume with reagent water. Prior to preparing the mixed standards, each stock solution should be analyzed separately to determine possible spectral interferences or the presence of impurities. Care should be taken when preparing the mixed standards to ensure that the elements are compatible and stable together. To minimize the opportunity for contamination by the containers, it is recommended to transfer the mixed-standard solutions to acid-cleaned, never-used FEP fluorocarbon (FEP) bottles for storage. Fresh mixed standards should be prepared, as needed, with the realization that concentrations can change on aging. Calibration standards not prepared from primary standards must be initially verified using a certified reference solution. For the recommended wavelengths listed in Table 1 some typical calibration standard combinations are given in Table 3 .

NOTE:

If the addition of silver to the recommended mixed-acid calibration standard results in an initial precipitation, add 15 mL of reagent water and warm the flask until the solution clears. For this acid combination, the silver concentration should be limited to 0 . 5 mg/L.

7.10 Blanks - Four types of blanks are required for the analysis.

The calibration blank is used in establishing the analytical curve, the laboratory reagent blank i s used to assess possible contamination from the sample preparation procedure, the laboratory fortified blank is used to assess routine l a b o r a t o r y performance and a rinse blank is Revision 4 . 4 May 1994

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used t o f l u s h t h e i n s t r i r m e n t u p t a k e system and n e b u l i z e r between standards, check solutions, and samples t o reduce memory interferences. 7 . 1 0 . 1 The c a l i b r a t i o n b l a n k f o r aqueous samples and e x t r a c t s i s prepared by a c i d i f y i n g reagent water to the same c o n c e n t r a t i o n s o f t h e a c i d s as used f o r t h e standards. The c a l i b r a t i o n b l a n k s h o u l d be s t o r e d i n a FEP b o t t l e . 7.10.2

The l a b o r a t o r y r e a g e n t b l a n k (LRB) must r e a g e n t s i n t h e same volumes as used i n t h e samples. The LRB must be c a r r i e d t h r o u g h p r e p a r a t i o n scheme as t h e samples i n c l u d i n g when appl icab1 e.

7.10.3

The l a b o r a t o r y f o r t i f i e d b l a n k (LFB) i s p r e p a r e d by f o r t i f y i n g an a l i q u o t o f t h e l a b o r a t o r y r e a g e n t b l a n k w i t h a l l a n a l y t e s t o a s u i t a b l e c o n c e n t r a t i o n u s i n g t h e f o l l o w i n g recommended c r i t e r i a : Ag 5 0 . 1 mg/L, 2 K 5 . 0 mg/L and a l l o t h e r a n a l y t e s 0.2 mg/L o r a c o n c e n t r a t i o n a p p r o x i m a t e l y 100 t i m e s t h e i r r e s p e c t i v e MDL, whichever i s g r e a t e r . The LFB must be c a r r i e d t h r o u g h t h e same e n t i r e p r e p a r a t i o n scheme as t h e samples i n c l u d i n g sample d i g e s t i o n , when a p p l i c a b l e .

7.10.4

The r i n s e b l a n k i s p r e p a r e d by a c i d i f y i n g reagent w a t e r t o t h e same c o n c e n t r a t i o n s o f a c i d s as used i n t h e c a l i b r a t i o n b l a n k and s t o r e d i n a c o n v e n i e n t manner.

contain a l l the processing o f the t h e same e n t i r e sample d i g e s t i o n ,

7.11 I n s t r u m e n t Performance Check (IPC) S o l u t i o n - The I P C s o l u t i o n i s used t o p e r i o d i c a l l y v e r i f y i n s t r u m e n t performance d u r i n g a n a l y s i s . It s h o u l d be p r e p a r e d i n t h e same a c i d m i x t u r e as t h e c a l i b r a t i o n standards by combining method a n a l y t e s a t a p p r o p r i a t e c o n c e n t r a t i o n s . S i l v e r must be l i m i t e d t o < 0.5 mg/L; w h i l e p o t a s s i u m and phosphorus because o f h i g h e r MDLs and s i l i c a because o f p o t e n t i a l c o n t a m i n a t i o n s h o u l d be a t c o n c e n t r a t i o n s o f 10 mg/L. For other analytes a c o n c e n t r a t i o n o f 2 mg/L i s recommended. The I P C s o l u t i o n s h o u l d be p r e p a r e d f r o m t h e same s t a n d a r d s t o c k s o l u t i o n s used t o p r e p a r e t h e c a l i b r a t i o n standards and s t o r e d i n an FEP b o t t l e . Agency programs may s p e c i f y o r r e q u e s t t h a t a d d i t i o n a l i n s t r u m e n t performance check s o l u t i o n s be p r e p a r e d a t s p e c i f i e d c o n c e n t r a t i o n s i n o r d e r t o meet p a r t i c u l a r program needs.

7 . 12 Q u a l i t y C o n t r o l Sample (QCS) - A n a l y s i s o f a QCS i s r e q u i r e d f o r i n i t i a l and p e r i o d i c v e r i f i c a t i o n o f c a l i b r a t i o n standards o r s t o c k s t a n d a r d s o l u t i o n s i n o r d e r t o v e r i f y i n s t r u m e n t performance. The QCS must be o b t a i n e d f r o m an o u t s i d e source d i f f e r e n t from t h e s t a n d a r d s t o c k s o l u t i o n s and p r e p a r e d i n t h e same a c i d m i x t u r e as t h e c a l i b r a t i o n s t a n d a r d s . The c o n c e n t r a t i o n o f t h e a n a l y t e s i n t h e QCS s o l u t i o n s h o u l d be 2 1 mg/L, e x c e p t s i l v e r , which must be l i m i t e d t o a c o n c e n t r a t i o n o f 0 . 5 mg/L f o r s o l u t i o n s t a b i l i t y . The QCS s o l u t i o n s h o u l d be s t o r e d i n a FEP b o t t l e and analyzed as needed t o meet d a t a q u a l i t y needs. A f r e s h s o l u t i o n s h o u l d be p r e p a r e d q u a r t e r l y o r more f r e q u e n t l y as needed. R e v i s i o n 4.4 Hay 1994

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7.13 Spectral

Interference Check ( S I C ) Solutions - When interelement corrections are applied, S I C solutions are needed containing concentrations of the interfering elements at levels that will provide an adequate test of the correction factors. 7.13.1

SIC solutions containing (a) 300 mg/L Fe; (b) 200 mg/L AL; (c) 50 mg/L Ba; (d) 50 mg/L Be; (e) 50 mg/L Cd; (f) 50 mg/L Ce; (9) 50 mg/L Co; (h) 50 mg/L Cr; ( i )50 mg/L Cu; (j) 50 mg/L Mn; (k) 50 mg/L Mo; (1) 50 mg/L Ni; (m) 50 mg/L Sn; (n) 50 mg/L SiO,; ( 0 ) 50 mg/L Ti; (p) 50 mg/L T1 and ( 4 ) 50 mg/L V should be prepared in the same acid mixture as the calibration standards and stored in FEP bottles. These solutions can be used to periodically verify a partial list of the on-line (and possible off-1 ine) interelement spectral correction factors for the recommended wavelengths given in Table 1. Other solutions could achieve the same objective as well. (Multielement SIC solutions3 may be prepared and substituted for the single element solutions provided an analyte i s nat subject to interference from more than one interferant in the sol ut i on. ) NOTE:

If wavelengths other than those recommended in Table 1 are used, other solutions different from those above (a thru q) may be required.

7.13.2

For interferences from iron and aluminum, only those correction factors (positive or negative) when multiplied by 100 to calculate apparent analyte concentrations that exceed the determined analyte IDL or fall below the lower 3-sigma control limit of the calibration blank need be tested on a dai 1 y basi s.

7.13.3

For the other interfering elements, only those correction factors (positive or negative) when multiplied by 10 to calculate apparent analyte concentrations that exceed the determined analyte IDL or fall below the lower 3-sigma control limit o f the calibration blank need be tested on a daily basis.

7.13.4

If the correction routine is operating properly, the determined apparent analyte(s) concentration from analysis of each interference solution (a thru q) should fall within a specific concentration range bracketing the calibration blank. This concentration range is calculated by multiplying the concentration of the interfering element by the value of the correction factor being tested and dividing by 10. If after subtraction of the calibration blank the apparent analyte concentration is outside (above or below) this range, a change in the correction factor of more than 10% should be suspected. The cause of the change should be determined and corrected and the correction factor should be updated. NOTE:

The SIC solution should be analyzed more than once to confirm a change has occurred with adequate rinse time Revision 4.4 May 1994

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between s o l u t i o n s and b e f o r e subsequent a n a l y s i s o f t h e c a l i b r a t i o n blank.

7.13.5

I f t h e c o r r e c t i o n f a c t o r s t e s t e d on a d a i l y b a s i s a r e found t o be w i t h i n t h e 10% c r i t e r i a f o r 5 c o n s e c u t i v e days, t h e r e q u i r e d v e r i f i c a t i o n frequency o f those f a c t o r s i n compliance may be extended t o a weekly b a s i s . A l s o , i f t h e n a t u r e o f t h e samples analyzed i s such ( e . g . , f i n i s h e d d r i n k i n g w a t e r ) t h a t t h e y do n o t c o n t a i n c o n c e n t r a t i o n s o f t h e i n t e r f e r i n g elements a t t h e lO-mg/L l e v e l , d a i l y v e r i f i c a t i o n i s n o t r e q u i r e d ; however, a1 1 i n t e r e l e m e n t s p e c t r a l c o r r e c t i o n f a c t o r s must be v e r i f i e d a n n u a l l y and updated, i f necessary.

7.13.6

I f t h e i n s t r u m e n t does n o t d i s p l a y n e g a t i v e c o n c e n t r a t i o n values, f o r t i f y t h e SIC s o l u t i o n s w i t h t h e elements o f i n t e r e s t a t 1 mg/L and t e s t f o r a n a l y t e r e c o v e r i e s t h a t a r e below 95%. I n t h e absence o f measurable a n a l y t e , overc o r r e c t i o n c o u l d go u n d e t e c t e d because a n e g a t i v e v a l u e c o u l d be r e p o r t e d as zero.

7.14 F o r i n s t r u m e n t s w i t h o u t i n t e r e l e m e n t c o r r e c t i o n c a p a b i l i t y o r when i n t e r e l e m e n t c o r r e c t i o n s a r e n o t used, SIC s o l u t i o n s ( c o n t a i n i n g s i m i l a r c o n c e n t r a t i o n s o f t h e m a j o r components i n t h e samples, e.g., can s e r v e t o v e r i f y t h e absence o f e f f e c t s a t t h e wavelengths s e l e c t e d . These d a t a must be k e p t on f i l e w i t h t h e sample a n a l y s i s d a t a . I f t h e SIC s o l u t i o n c o n f i r m s an o p e r a t i v e i n t e r f e r e n c e t h a t i s 2 10% o f t h e a n a l y t e c o n c e n t r a t i o n , t h e a n a l y t e must be d e t e r m i n e d u s i n g a wavelength and background c o r r e c t i o n l o c a t i o n f r e e o f t h e i n t e r f e r e n c e o r by a n o t h e r approved t e s t procedure. Users a r e a d v i s e d t h a t h i g h s a l t c o n c e n t r a t i o n s can cause a n a l y t e s i g n a l suppressions and confuse i n t e r f e r e n c e t e s t s . 2 10 mg/L)

7.15 Plasma S o l u t i o n - The plasma s o l u t i o n i s used f o r d e t e r m i n i n g t h e optimum v i e w i n g h e i g h t o f t h e plasma above t h e work c o i l p r i o r t o u s i n g t h e method ( S e c t . 10.2). The s o l u t i o n i s p r e p a r e d by adding a 5-mL a l i q u o t f r o m each o f t h e s t o c k s t a n d a r d s o l u t i o n s o f a r s e n i c , l e a d , selenium, and t h a l l i u m t o a m i x t u r e o f 20 mL (ltl) n i t r i c a c i d and 20 mL (ltl) h y d r o c h l o r i c a c i d and d i l u t i n g t o 500 mL w i t h r e a g e n t w a t e r . S t o r e i n a FEP b o t t l e . 8.0

SAMPLE COLLECTION, PRESERVATION, AND STORAGE

8.1

P r i o r t o t h e c o l l e c t i o n o f an aqueous sample, c o n s i d e r a t i o n s h o u l d be given t o t h e type o f data required, (i.e., dissolved o r t o t a l r e c o v e r a b l e ) , so t h a t a p p r o p r i a t e p r e s e r v a t i o n and p r e t r e a t m e n t steps can be t a k e n . The pH o f a l l aqueous samples must be t e s t e d i m m e d i a t e l y p r i o r t o a1 i q u o t i n g f o r p r o c e s s i n g o r " d i r e c t a n a l y s i s " t o ensure t h e sample has been p r o p e r l y p r e s e r v e d . If properly acid preserved, t h e sample can be h e l d up t o 6 months b e f o r e a n a l y s i s .

8.2

F o r t h e d e t e r m i n a t i o n o f t h e d i s s o l v e d elements, t h e sample must be f i l t e r e d t h r o u g h a 0.45-pm p o r e d i a m e t e r membrane f i l t e r a t t h e t i m e o f c o l l e c t i o n o r as soon t h e r e a f t e r as p r a c t i c a l l y p o s s i b l e . (Glass o r p l a s t i c f i l t e r i n g apparatus a r e recommended t o a v o i d p o s s i b l e R e v i s i o n 4.4 Hay 1994

52

Methods for the Determination contamination. Only p l a s t i c apparatus should be used when t h e d e t e r m i n a t i o n s o f boron and s i l i c a a r e c r i t i c a l . ) Use a p o r t i o n o f t h e f i l t e r e d sample t o r i n s e t h e f i l t e r f l a s k , d i s c a r d t h i s p o r t i o n and c o l l e c t t h e r e q u i r e d volume o f f i l t r a t e . A c i d i f y t h e f i l t r a t e w i t h (It\) n i t r i c a c i d i m m e d i a t e l y f o l l o w i n g f i ' \ t r a t i o n t o pH < 2. 8.3

F o r t h e d e t e r m i n a t i o n o f t o t a l r e c o v e r a b l e elements i n aqueous samples, samples a r e n o t f i l t e r e d , b u t a c i d i f i e d w i t h ( l t l ) n i t r i c a c i d t o pH < 2 ( n o r m a l l y , 3 mL o f ( l t l ) a c i d p e r l i t e r o f sample i s s u f f i c i e n t f o r most ambient and d r i n k i n g w a t e r samples). P r e s e r v a t i o n may be done a t t h e t i m e o f c o l l e c t i o n , however, t o a v o i d t h e hazards o f s t r o n g a c i d s i n t h e f i e l d , t r a n s p o r t r e s t r i c t i o n s , and p o s s i b l e c o n t a m i n a t i o n i t i s recommended t h a t t h e samples be r e t u r n e d t o t h e l a b o r a t o r y w i t h i n two weeks o f c o l l e c t i o n and a c i d p r e s e r v e d upon r e c e i p t i n t h e l a b o r a t o r y . F o l l o w i n g a c i d i f i c a t i o n , t h e sample s h o u l d be mixed, h e l d f o r s i x t e e n hours, and t h e n v e r i f i e d t o be pH < 2 j u s t p r i o r w i t h d r a w i n g an a l i q u o t f o r p r o c e s s i n g o r " d i r e c t a n a l y s i s " . I f f o r some reason such as h i g h a l k a l i n i t y t h e sample pH i s v e r i f i e d t o be > 2 , more a c i d must be added and t h e sample h e l d f o r s i x t e e n hours u n t i l v e r i f i e d t o be pH < 2. See S e c t i o n 8.1.

NOTE:

9.0

When t h e n a t u r e o f t h e sample i s e i t h e r unknown o r i s known t o be hazardous, a c i d i f i c a t i o n s h o u l d be done i n a fume hood. See S e c t i o n 5 . 2 .

8.4

S o l i d samples r e q u i r e no p r e s e r v a t i o n p r i o r t o a n a l y s i s o t h e r t h a n s t o r a g e a t 4°C. There i s no e s t a b l i s h e d h o l d i n g t i m e l i m i t a t i o n f o r s o l i d samples.

8.5

For aqueous samples, a f i e l d b l a n k should be prepared and analyzed as r e q u i r e d by t h e d a t a u s e r . Use t h e same c o n t a i n e r and a c i d as used i n sample c o l l e c t i o n .

QUALITY CONTROL 9.1

Each l a b o r a t o r y u s i n g t h i s method i s r e q u i r e d t o o p e r a t e a f o r m a l qua1 i t y c o n t r o l (QC) program. The minimum r e q u i r e m e n t s o f t h i s program c o n s i s t o f an i n i t i a l d e m o n s t r a t i o n o f l a b o r a t o r y c a p a b i l i t y , and t h e p e r i o d i c a n a l y s i s o f l a b o r a t o r y r e a g e n t blanks, f o r t i f i e d b l a n k s and o t h e r l a b o r a t o r y s o l u t i o n s as a c o n t i n u i n g check on performance. The l a b o r a t o r y i s r e q u i r e d t o m a i n t a i n performance r e c o r d s t h a t d e f i n e t h e q u a l i t y o f t h e d a t a t h u s generated.

9.2

I n i t i a l Demonstration o f Performance (mandatory), 9.2.1

The i n i t i a l d e m o n s t r a t i o n o f performance i s used t o c h a r a c t e r i z e i n s t r u m e n t performance ( d e t e r m i n a t i o n o f l i n e a r dynamic ranges and a n a l y s i s o f q u a l i t y c o n t r o l samples) and l a b o r a t o r y performance ( d e t e r m i n a t i o n o f method d e t e c t i o n l i m i t s ) p r i o r t o analyses conducted by t h i s method.

9.2.2

L i n e a r dynamic range (LDR) - The upper l i m i t o f t h e LDR must be e s t a b l i s h e d f o r each wavelength u t i l i z e d . I t must be R e v i s i o n 4.4 Hay 1994

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d e t e r m i n e d f r o m a l i n e a r c a l i b r d t i o n p r e p a r e d i n t h e normal manner u s i n g t h e e s t a b l i s h e d a n a l y t i c a l o p e r a t i n g p r o c e d u r e f o r t h e i n s t r u m e n t . The LDR s h o u l d be d e t e r m i n e d b y a n a l y z i n g succeedingly higher standard concentrations o f the analyte u n t i l t h e o b s e r v e d a n a l y t e c o n c e n t r a t i o n i s no more t h a n 10% below t h e s t a t e d c o n c e n t r a t i o n o f t h e standard. Determined LDRs must be documented and k e p t on f i l e . The LDR w h i c h may be u s e d f o r t h e a n a l y s i s o f samples s h o u l d be j u d g e d b y t h e a n a l y s t f r o m t h e r e s u l t i n g d a t a . D e t e r m i n e d sample a n a l y t e c o n c e n t r a t i o n s t h a t a r e g r e a t e r t h a n 90% o f t h e d e t e r m i n e d u p p e r LDR l i m i t must be d i l u t e d and r e a n a l y z e d . The LDRs s h o u l d be v e r i f i e d a n n u a l l y o r whenever, i n t h e judgement o f t h e a n a l y s t , a change i n a n a l y t i c a l p e r f o r m a n c e caused by e i t h e r a change i n i n s t r u m e n t h a r d w a r e o r o p e r a t i n g c o n d i t i o n s w o u l d d i c t a t e t h e y be r e d e t e r m i n e d .

9.2.3

Q u a l i t y c o n t r o l sample ( Q C S ) - When b e g i n n i n g t h e use o f t h i s method, on a q u a r t e r l y b a s i s , a f t e r t h e p r e p a r a t i o n o f s t o c k o r c a l i b r a t i o n s t a n d a r d s o l u t i o n s o r as r e q u i r e d t o meet d a t a qua1 i t y needs, v e r i f y t h e c a l i b r a t i o n s t a n d a r d s and a c c e p t a b l e i n s t r u m e n t p e r f o r m a n c e w i t h t h e p r e p a r a t i o n and a n a l y s e s o f a QCS ( S e c t . 7 . 1 2 ) . To v e r i f y t h e c a l i b r a t i o n s t a n d a r d s t h e d e t e r m i n e d mean c o n c e n t r a t i o n s f r o m 3 a n a l y s e s o f t h e QCS must be w i t h i n _+ 5% o f t h e s t a t e d v a l u e s . I f the calibration s t a n d a r d c a n n o t be v e r i f i e d , . p e r f o r m a n c e o f t h e d e t e r m i n a t i v e s t e p o f t h e method i s u n a c c e p t a b l e . The s o u r c e o f t h e p r o b l e m must be i d e n t i f i e d and c o r r e c t e d b e f o r e e i t h e r p r o c e e d i n g on w i t h t h e i n i t i a l d e t e r m i n a t i o n o f method d e t e c t i o n l i m i t s o r c o n t i n u i n g w i t h on-going analyses.

9.2.4

Method d e t e c t i o n l i m i t (MDL) - MDLs m u s t be e s t a b l i s h e d f o r a l l wavelengths u t i l i z e d , u s i n g reagent water (blank) f o r t i f i e d a t a concentration o f twy5 t o three times t h e estimated instrument detection l i m i t . To d e t e r m i n e MDL v a l u e s , t a k e seven r e p l i c a t e a l i q u o t s o f t h e f o r t i f i e d r e a g e n t w a t e r and p r o c e s s t h r o u g h t h e e n t i r e a n a l y t i c a l method. P e r f o r m a l l c a l c u l a t i o n s d e f i n e d i n t h e method and r e p o r t t h e c o n c e n t r a t i o n v a l u e s i n t h e a p p r o p r i a t e u n i t s . C a l c u l a t e t h e MDL as f o l l o w s : MDL

=

( t ) x (S)

where: t

S

Note:

s t u d e n t s ’ t v a l u e f o r a 99% c o n f i d e n c e l e v e l and a standard d e v i a t i o n e s t i m a t e w i t h n-1 degrees o f freedom [ t = 3 . 1 4 f o r seven r e p l i c a t e s ] .

=

=

standard d e v i a t i o n o f t h e r e p l i c a t e analyses.

I f additional confirmation i s desired, reanalyze the seven r e p 1 i c a t e a1 i q u o t s on t w o more n o n c o n s e c u t i v e d a y s and a g a i n c a l c u l a t e t h e MDL v a l u e s f o r each day. An a v e r a g e o f t h e t h r e e MDL v a l u e s f o r each a n a l y t e If may p r o v i d e f o r a more a p p r o p r i a t e MDL e s t i m a t e . t h e r e l a t i v e s t a n d a r d d e v i a t i o n (RSD) f r o m t h e a n a l y s e s R e v i s i o n 4 . 4 May1994

54

Methods for the Determination o f t h e seven a l i q u o t s i s < l o % , t h e c o n c e n t r a t i o n used t o d e t e r m i n e t h e a n a l y t e MDL may have been inappropr i a t e l y h i g h f o r t h e d e t e r m i n a t i o n . I f so, t h i s c o u l d r e s u l t i n t h e c a l c u l a t i o n o f an u n r e a l i s t i c a l l y l o w MDL. C o n c u r r e n t l y , d e t e r m i n a t i o n o f MDL i n r e a g e n t w a t e r r e p r e s e n t s a b e s t case s i t u a t i o n and does n o t r e f l e c t p o s s i b l e m a t r i x e f f e c t s o f r e a l w o r l d samples. However, s u c c e s s f u l analyses o f LFMs ( S e c t . 9.4) and the analyte a d d i t i o n t e s t described i n Section 9.5.1 can g i v e c o n f i d e n c e t o t h e MDL v a l u e determined i n r e a g e n t w a t e r . T y p i c a l s i n g l e l a b o r a t o r y MDL v a l u e s u s i n g t h i s method a r e g i v e n i n Table 4 . The MDLs must be s u f f i c i e n t t o d e t e c t a n a l y t e s a t t h e r e q u i r e d l e v e l s a c c o r d i n g t o compliance m o n i t o r i n g r e g u l a t i o n (Sect. 1 . 2 ) . MDLs s h o u l d be d e t e r m i n e d a n n u a l l y , when a new o p e r a t o r b e g i n s work o r whenever, i n t h e judgement o f t h e a n a l y s t , a change i n a n a l y t i c a l performance caused by e i t h e r a change i n i n s t r u m e n t hardware o r o p e r a t i n g c o n d i t i o n s would d i c t a t e t h e y be r e d e t e r m i n e d . 9.3

Assessing L a b o r a t o r y Performance (mandatory) 9.3.1

L a b o r a t o r y r e a g e n t b l a n k (LRB) - The l a b o r a t o r y must analyze a t l e a s t one LRB ( S e c t . 7.10.2) w i t h each b a t c h of 20 o r fewer samples o f t h e same m a t r i x . LRB d a t a a r e used t o assess c o n t a m i n a t i o n f r o m t h e l a b o r a t o r y environment. LRB v a l u e s t h a t exceed t h e MDL i n d i c a t e l a b o r a t o r y o r r e a g e n t c o n t a m i n a t i o n s h o u l d be suspected. When LRB v a l u e s c o n s t i t u t e 10% o r more o f t h e a n a l y t e l e v e l determined f o r a sample o r i s 2.2 t i m e s t h e a n a l y t e MDL whichever i s g r e a t e r , f r e s h a l i q u o t s o f t h e samples must be p r e p a r e d and analyzed a g a i n f o r t h e a f f e c t e d a n a l y t e s a f t e r t h e source o f c o n t a m i n a t i o n has been c o r r e c t e d and a c c e p t a b l e LRB v a l u e s have been o b t a i n e d .

9.3.2

L a b o r a t o r y f o r t i f i e d b l a n k (LFB) - The l a b o r a t o r y must analyze a t l e a s t one LFB ( S e c t . 7.10.3) w i t h each b a t c h o f samples. C a l c u l a t e accuracy as p e r c e n t r e c o v e r y u s i n g t h e f o l l o w i n g equation:

R =

LFB - LRB

x

100

S

where:

R LFB LRB

= =

s

=

=

percent recovery. l a b o r a t o r y f o r t i f i e d blank. l a b o r a t o r y reagent blank. concentration equivalent o f analyte added t o f o r t i f y t h e LBR s o l u t i o n .

I f t h e r e c o v e r y o f any a n a l y t e f a l l s o u t s i d e t h e r e q u i r e d c o n t r o l l i m i t s o f 85-115%, t h a t a n a l y t e i s judged o u t o f R e v i s i o n 4 . 4 Hay 1994

Metals

55

c o n t r o l , and t h e source o f t h e problem s h o u l d be i d e n t i f i e d and resolved before continuing analyses. 9.3.3

The l a b o r a t o r y must use LFB analyses d a t a t o assess l a b o r a t o r y performance a g a i n s t t h e r e q u i r e d c o n t r o l l i m i t s o f 85-115% ( S e c t . 9 . 3 . 2 ) . When s u f f i c i e n t i n t e r n a l performance d a t a become a v a i l a b l e ( u s u a l l y a minimum o f t w e n t y t o t h i r t y a n a l y s e s ) , o p t i o n a l c o n t r o l l i m i t s can be developed from t h e mean p e r c e n t r e c o v e r y ( x ) and t h e s t a n d a r d d e v i a t i o n ( S ) o f t h e mean p e r c e n t r e c o v e r y . These d a t a can be used t o e s t a b l i s h t h e upper and l o w e r c o n t r o l l i m i t s as f o l l o w s :

UPPER CONTROL L I M I T LOWER CONTROL LIMIT

= =

x t 3s x - 3s

The o p t i o n a l c o n t r o l 1 i m i t s must be equal t o o r b e t t e r t h a n t h e r e q u i r e d c o n t r o l l i m i t s o f 85-115%. A f t e r each f i v e t o t e n new r e c o v e r y measurements, new c o n t r o l 1 i m i t s can be c a l c u l a t e d u s i n g o n l y t h e most r e c e n t t w e n t y t o t h i r t y d a t a p o i n t s . Also, t h e s t a n d a r d d e v i a t i o n ( S ) d a t a s h o u l d be used t o e s t a b l i s h an on-going p r e c i s i o n statement f o r t h e l e v e l o f c o n c e n t r a t i o n s i n c l u d e d i n t h e LFB. These d a t a must be k e p t on f i l e and be a v a i l a b l e f o r review. 9.3.4

I n s t r u m e n t performance check (IPC) s o l u t i o n - For a l l d e t e r m i n a t i o n s t h e l a b o r a t o r y must analyze t h e I P C s o l u t i o n ( S e c t . 7.11) and a c a l i b r a t i o n b l a n k immediately f o l l o w i n g daily calibration, a f t e r e v e r y t e n t h sample ( o r more f r e q u e n t l y , i f r e q u i r e d ) and a t t h e end o f t h e sample r u n . A n a l y s i s o f t h e c a l i b r a t i o n b l a n k s h o u l d always be < t h e a n a l y t e IDL, b u t > t h e l o w e r 3-sigma c o n t r o l l i m i t o f t h e c a l i b r a t i o n b l a n k . A n a l y s i s o f t h e I P C s o l u t i o n immediately f o l l o w i n g c a l i b r a t i o n must v e r i f y t h a t t h e i n s t r u m e n t i s w i t h i n k 5% o f c a l i b r a t i o n w i t h a r e l a t i v e s t a n d a r d d e v i a t i o n < 3% f r o m r e p l i c a t e i n t e g r a t i o n s 2 4. Subsequent analyses o f t h e I P C s o l u t i o n must be w i t h i n k 10% o f c a l i b r a t i o n . I f the c a l i b r a t i o n cannot be v e r i f i e d w i t h i n t h e s p e c i f i e d l i m i t s , r e a n a l y z e e i t h e r o r b o t h t h e I P C s o l u t i o n and t h e c a l i b r a t i o n I f t h e second a n a l y s i s o f t h e I P C s o l u t i o n or t h e blank. c a l i b r a t i o n b l a n k c o n f i r m c a l i b r a t i o n t o be o u t s i d e t h e l i m i t s , sample a n a l y s i s must be d i s c o n t i n u e d , t h e cause determined, A l l samples c o r r e c t e d and/or t h e i n s t r u m e n t r e c a l i b r a t e d . f o l l o w i n g t h e l a s t a c c e p t a b l e I P C s o l u t i o n must be r e a n a l y z e d . The a n a l y s i s d a t a o f t h e c a l i b r a t i o n b l a n k and I P C s o l u t i o n must be k e p t on f i l e w i t h t h e sample analyses d a t a .

9.3.5

Spectral i n t e r f e r e n c e check (SIC) s o l u t i o n - F o r a l l d e t e r m i n a t i o n s t h e l a b o r a t o r y must p e r i o d i c a l l y v e r i f y t h e i n t e r e l e m e n t s p e c t r a l i n t e r f e r e n c e c o r r e c t i o n r o u t i n e by a n a l y z i n g SIC s o l u t i o n s . The p r e p a r a t i o n and r e q u i r e d p e r i o d i c a n a l y s i s o f S I C s o l u t i o n s and t e s t c r i t e r i a f o r v e r i f y i n g t h e interelement i n t e r f e r e n c e c o r r e c t i o n r o u t i n e are given i n S p e c i a l cases where on-going v e r i f i c a t i o n i s Section 7.13. r e q u i r e d a r e d e s c r i b e d i n S e c t i o n 7.14. R e v i s i o n 4.4 Hay 1994

56


9.4

Assessing Analyte R e c n v i l r y arid D a t a Qua1i t y 9.4.1

Sample homoqeiwiiy ‘itid t h e chemical n a t u r e of t h e sample m a t r i x can a f f e c t a n a l y t e recovery and t h e q u a l i t y o f t h e d a t a . Taking s e p a r a t e a l i q u o t s from t h e sample f o r r e p l i c a t e and f o r t i f i e d a n a l y s e s can i n some c a s e s a s s e s s t h e e f f e c t . Unless o t h e r w i s e s p e c i f led by t h e d a t a u s e r , l a b o r a t o r y o r program, t h e f o l l o w i n g 1aborat.nt-y f o r t i f i e d m a t r i x ( L F M ) procedure ( S e c t 9 . 4 . 2 ) i s r e q u i r e d . Also, o t h e r t e s t s such a s t h e a n a l y t e a d d i t i o n t e s t ( S e c t . 9 . 5 . 1 ) and sample d i l u t i o n t e s t ( S e c t . 9 . 5 . 2 ) can i n d i c a t e i f m a t r i x e f f e c t s a r e o p e r a t i v e .

9.4.2

The l a b o r a t o r y must add a known amount of each a n a l y t e t o a minimum of 10% of t h e r o u t i n e samples. I n each c a s e t h e LFM a l i q u o t must be a d u p l i c a t e of t h e a l i q u o t used f o r sample a n a l y s i s and f o r t o t a l r e c o v e r a b l e d e t e r m i n a t i o n s added p r i o r t o sample p r e p a r a t i o n . For water samples, t h e added a n a l y t e c o n c e n t r a t i o n must be t h e same a s t h a t used i n t h e l a b o r a t o r y f o r t i f i e d blank ( S e c t . 7 . 1 0 . 3 ) . For s o l i d samples, however, t h e c o n c e n t r a t i o n added should be e x p r e s s e d a s mg/kg and i s c a l c u l a t e d f o r a one gram a l i q u o t by m u l t i p l y i n g t h e added a n a l y t e c o n c e n t r a t i o n (mg/L) i n s o l u t i o n by t h e conversion f a c t o r 100 (mg/L x O.lL/O.OOlkg = 100, S e c t . 1 2 . 5 ) . ( F o r n o t e s on Ag, Ba, and Sn s e e S e c t s . 1 . 7 & 1 . 8 . ) Over t i m e , samples from a l l r o u t i n e sample s o u r c e s should be f o r t i f i e d . NOTE:

The c o n c e n t r a t i o n o f c a l c i u m , magnesium, sodium and s t r o n t i u m in environmental w a t e r s , along with i r o n and aluminum i n s o l i d s can vary g r e a t l y and a r e not necessarily predictable. Fortifying these analytes in r o u t i n e samples a t the same c o n c e n t r a t i o n used f o r the LFB may prove t o be o f l i t t l e use i n a s s e s s i n g d a t a q u a l i t y f o r t h e s e a n a l y t e s . For t h e s e a n a l y t e s sample d i l u t i o n and r e a n a l y s i s u s i n g t h e c r i t e r i a given i n S e c t i o n 9 . 5 . 2 i s recommended. Also, i f s p e c i f i e d by t h e d a t a u s e r , l a b o r a t o r y o r program, samples can be f o r t i f i e d a t h i g h e r c o n c e n t r a t i o n s , b u t even major c o n s t i t u e n t s should be l i m i t e d t o < 25 mg/L so a s n o t t o a l t e r t h e sample m a t r i x and a f f e c t t h e a n a l y s i s .

9 . 4 . 3 C a l c u l a t e the percent recovery f o r each a n a l y t e , c o r r e c t e d f o r background c o n c e n t r a t i o n s measured i n t h e u n f o r t i f i e d sample, and compare t h e s e v a l u e s t o t h e d e s i g n a t e d LFM r e c o v e r y range of 70-130% o r a 3 sigma recovery ra:$e c a l c u l a t e d from t h e r e g r e s s i o n e q u a t i o n s given i n Table 9 . Recovery c a l c u l a t i o n s a r e n o t r e q u i r e d i f t h e c o n c e n t r a t i o n added i s l e s s than 30% o f t h e sample background c o n c e n t r a t i o n . Percent r e c o v e r y may be c a l c u l a t e d i n u n i t s a p p r o p r i a t e t o t h e m a t r i x , using the following equation:

Revision 4 . 4 Hay 1994

Metals where:

9.5

R C, C s

= = = =

57

percent recovery. f o r t i f i e d sample c o n c e n t r a t i o n . sample background c o n c e n t r a t i o n . concentration equivalent o f analyte added t o f o r t i f y t h e sample.

9.4.4

I f t h e r e c o v e r y o f any a n a l y t e f a l l s o u t s i d e t h e d e s i g n a t e d LFM r e c o v e r y range, and t h e l a b o r a t o r y performance f o r t h a t a n a l y t e i s shown t o be i n c o n t r o l ( S e c t . 9 . 3 ) , t h e r e c o v e r y problem encountered w i t h t h e f o r t i f i e d sample i s judged t o be m a t r i x r e l a t e d , n o t system r e l a t e d . The d a t a u s e r s h o u l d be i n f o r m e d t h a t t h e r e s u l t f o r t h a t a n a l y t e i n t h e u n f o r t i f i e d sample i s suspect due t o e i t h e r t h e heterogeneous n a t u r e o f t h e sample or m a t r i x e f f e c t s and a n a l y s i s by method o f s t a n d a r d a d d i t i o n o r t h e use o f an i n t e r n a l s t a n d a r d ( s ) ( S e c t . 11.5) should be considered.

9.4.5

Where r e f e r e n c e m a t e r i a l s a r e a v a i l a b l e , t h e y s h o u l d be analyzed t o p r o v i d e a d d i t i o n a l performance d a t a . The a n a l y s i s o f r e f e r e n c e samples is a v a l u a b l e t o o l f o r d e m o n s t r a t i n g t h e a b i l i t y t o p e r f o r m t h e method a c c e p t a b l y . Reference m a t e r i a l s c o n t a i n i n g h i g h c o n c e n t r a t i o n s o f a n a l y t e s can p r o v i d e a d d i t i o n a l i n f o r m a t i o n on t h e performance o f t h e s p e c t r a l interference correction routine.

Assess t h e p o s s i b l e need f o r t h e method o f s t a n d a r d a d d i t i o n s (MSA) o r i n t e r n a l s t a n d a r d elements by t h e f o l l o w i n g t e s t s . Directions f o r u s i n g MSA o r i n t e r n a l s t a n d a r d ( s ) a r e g i v e n i n S e c t i o n 11.5. 9.5.1

A n a l y t e a d d i t i o n t e s t : An a n a l y t e ( s ) s t a n d a r d added t o a p o r t i o n o f a p r e p a r e d sample, o r i t s d i l u t i o n , s h o u l d be The r e c o v e r e d t o w i t h i n 85% t o 115% o f t h e known v a l u e . a n a l y t e ( s ) a d d i t i o n s h o u l d produce a minimum l e v e l o f 20 t i m e s and a maximum o f 100 t i m e s t h e method d e t e c t i o n l i m i t . I f t h e a n a l y t e a d d i t i o n i s < 20% o f t h e sample a n a l y t e c o n c e n t r a t i o n , t h e f o l l o w i n g d i l u t i o n t e s t s h o u l d be used. I f r e c o v e r y o f t h e analyte(s) i s not w i t h i n the specified l i m i t s , a matrix e f f e c t s h o u l d be suspected, and t h e a s s o c i a t e d d a t a f l a g g e d accordingly. The method o f a d d i t i o n s o r t h e use o f an a p p r o p r i a t e i n t e r n a l s t a n d a r d element may p r o v i d e more a c c u r a t e data.

9.5.2

D i l u t i o n test: I f the analyte concentration i s s u f f i c i e n t l y h i g h ( m i n i m a l l y , a f a c t o r o f 50 above t h e i n s t r u m e n t d e t e c t i o n l i m i t i n t h e o r i g i n a l s o l u t i o n b u t < 90% o f t h e l i n e a r l i m i t ) , an a n a l y s i s of a 1t4 d i l u t i o n s h o u l d agree ( a f t e r c o r r e c t i o n f o r t h e f i v e f o l d d i l u t i o n ) w i t h i n f 10% o f t h e o r i g i n a l determination. I f n o t , a chemical o r p h y s i c a l i n t e r f e r e n c e e f f e c t s h o u l d be suspected and t h e a s s o c i a t e d d a t a f l a g g e d a c c o r d i n g l y . The method o f s t a n d a r d a d d i t i o n s o r t h e use o f an i n t e r n a l - s t a n d a r d element may p r o v i d e more a c c u r a t e d a t a f o r samples f a i l i n g t h i s t e s t . R e v i s i o n 4.4 May 1994

58


10.0 CALIBRATION AND STANDARDIZATION

1 0 . 1 S p e c i f i c w a v e l e n g t h s a r e l i s t e d i n T a b l e 1. O t h e r w a v e l e n g t h s may be s u b s t i t u t e d i f t h e y can p r o v i d e t h e needed s e n s i t i v i t y and a r e corrected f o r spectral interference. However, because o f t h e d i f f e r e n c e among v a r i o u s makes and models o f s p e c t r o m e t e r s , s p e c i f i c i n s t r u m e n t o p e r a t i n g c o n d i t i o n s c a n n o t be g i v e n . The i n s t r u m e n t and o p e r a t i n g c o n d i t i o n s u t i l i z e d f o r d e t e r m i n a t i o n must be c a p a b l e o f p r o v i d i n g d a t a o f a c c e p t a b l e q u a l i t y t o t h e p r o g r a m and d a t a u s e r . The a n a l y s t s h o u l d f o l l o w t h e i n s t r u c t i o n s p r o v i d e d b y t h e i n s t r u m e n t manufacturer unless other conditions provide s i m i l a r o r b e t t e r p e r f o r m a n c e f o r a t a s k . O p e r a t i n g c o n d i t i o n s f o r aqueous s o l u t i o n s u s u a l l y v a r y f r o m 1100 t o 1200 w a t t s f o r w a r d power, 1 5 - t o 16-mm v i e w i n g h e i g h t , 15 t o 19 l i t e r s / m i n a r g o n c o o l a n t f l o w , 0 . 6 t o 1 L / m i n a r g o n a e r o s o l f l o w , 1 t o 1.8 mL/min sample pumping r a t e w i t h a l - m i n p r e f l u s h t i m e and measurement t i m e n e a r 1 s p e r w a v e l e n g t h peak ( f o r s e q u e n t i a l i n s t r u m e n t s ) and n e a r 10 s p e r sample ( f o r s i m u l t a n e o u s instruments). Use o f t h e Cu/Mn i n t e n s i t y r a t i o a t 324.754 nm and 257.610 nm (by a d j u s t i n g t h e a r g o n a e r o s o l f l o w ) has been recommended as a way t o a c h i e v e r e p e a t a b l e i n t e r f e r e n c e c o r r e c t i o n f a c t o r s . ” 10.2 P r i o r t o u s i n g t h i s method o p t i m i z e t h e plasma o p e r a t i n g c o n d i t i o n s . The f o l l o w i n g p r o c e d u r e i s recommended f o r v e r t i c a l l y c o n f i g u r e d plasmas. The p u r p o s e o f plasma o p t i m i z a t i o n i s t o p r o v i d e a maximum signal-to-background r a t i o f o r t h e l e a s t s e n s i t i v e elgment i n t h e a n a l y t i c a l a r r a y . The use o f a mass f l o w c o n t r o l l e r t o r e g u l a t e t h e n e b u l i z e r gas f l o w r a t e g r e a t l y f a c i l i t a t e s t h e p r o c e d u r e . 1 0 . 2 . 1 I g n i t e t h e plasma and s e l e c t an a p p r o p r i a t e i n c i d e n t r f power w i t h minimum r e f l e c t e d power. A l l o w t h e i n s t r u m e n t t o become thermally stable before beginning. This usually requires a t l e a s t 30 t o 60 m i n u t e s o f o p e r a t i o n . While a s p i r a t i n g t h e 1000-pg/mL s o l u t i o n o f y t t r i u m ( S e c t . 7.8.32), follow the i n s t r u m e n t m a n u f a c t u r e r ’ s i n s t r u c t i o n s and a d j u s t t h e a e r o s o l c a r r i e r gas f l o w r a t e t h r o u g h t h e n e b u l i z e r so a d e f i n i t i v e b l u e e m i s s i o n r e g i o n o f t h e plasma e x t e n d s a p p r - t x i m a t e l y f r o m 5 t o 20 mm above t h e t o p o f t h e w o r k c o i l . Record t h e n e b u l i z e r gas f l o w r a t e o r p r e s s u r e s e t t i n g f o r f u t u r e reference. 10.2.2 A f t e r e s t a b l i s h i n g t h e n e b u l i z e r gas f l o w r a t e , d e t e r m i n e t h e s o l u t i o n u p t a k e r a t e o f t h e n e b u l i z e r i n mL/min by a s p i r a t i n g a known volume c a l i b r a t i o n b l a n k f o r a p e r i o d o f a t l e a s t 3 m i n u t e s . D i v i d e t h e s p e n t volume by t h e a s p i r a t i o n t i m e ( i n m i n u t e s ) and r e c o r d t h e u p t a k e r a t e . S e t t h e p e r i s t a l t i c pump t o d e l i v e r t h e u p t a k e r a t e i n a s t e a d y even f l o w . 10.2.3 A f t e r h o r i z o n t a l l y a l i g n i n g t h e plasma a n d / o r o p t i c a l l y p r o f i l i n g t h e s p e c t r o m e t e r , use t h e s e l e c t e d i n s t r u m e n t c o n d i t i o n s f r o m S e c t i o n s 1 0 . 2 . 1 and 10.2.2, and a s p i r a t e t h e plasma s o l u t i o n ( S e c t . 7 . 1 5 ) , c o n t a i n i n g 10 pg/mL each o f A s , Pb, Se and T1. C o l l e c t i n t e n s i t y d a t a a t t h e w a v e l e n g t h peak f o r each a n a l y t e a t 1 mm i n t e r v a l s f r o m 14 t o 18 mm above t h e t o p o f t h e work c o i l . ( T h i s r e g i o n o f t h e plasma i s commonly R e v i s i o n 4.4 May 1994

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r e f e r r e d t o a s t h e a n a l y t i c a l zone.)'' Repeat t h e process u s i n g t h e c a l i b r a t i o n b l a n k . Determine t h e n e t s i g n a l t o b l a n k i n t e n s i t y r a t i o f o r each a n a l y t e f o r each v i e w i n g h e i g h t s e t t . i n y . Choose t h e h e i g h t f o r v i e w i n g t h e plasma t h a t p r o v i d e s t h e l a r g e s t i n t e n s i t y r a t i o f o r t h e l e a s t s e n s i t i v e element o f t h e f o u r a n a l y t e s . I f more t h a n one p o s i t i o n p r o v i d e s t h e same r a t i o , s e l e c t the p o s i t i o n t h a t provides the highest n e t i n t e n s i t y c o u n t s f o r t h e l e a s t s e n s i t i v e element o r accept a compromise p o s i t i o n o f t h e i n t e n s i t y r a t i o s o f a l l f o u r analytes. 10.2.4 The i n s t r u m e n t o p e r a t i n g c o n d i t i o n f i n a l l y s e l e c t e d as b e i n g optimum should p r o v i d e t h e l o w e s t r e l i a b l e i n s t r u m e n t d e t e c t i o n l i m i t s and method d e t e c t i o n l i m i t s . R e f e r t o Tables 1 and 4 f o r comparison o f I D L s and MDLs, r e s p e c t i v e l y . 10.2.5 I f e i t h e r t h e i n s t r u m e n t o p e r a t i n g c o n d i t i o n s , such as i n c i d e n t power and/or n e b u l i z e r gas f l o w r a t e a r e changed, o r a new t o r c h i n j e c t o r tube having a d i f f e r e n t o r i f i c e i . d . i s i n s t a l l e d , t h e plasma and plasma v i e w i n g h e i g h t should be reoptimized. 10.2.6 B e f o r e d a i l y c a l i b r a t i o n and a f t e r t h e i n s t r u m e n t warmup p e r i o d , t h e n e b u l i z e r gas f l o w must be r e s e t t o t h e determined o p t i m i z e d f l o w . I f a mass .flow c o n t r o l l e r i s b e i n g used, i t s h o u l d be r e s e t t o t h e r e c o r d e d o p t i m i z e d f l o w r a t e . I n o r d e r t o m a i n t a i n Val i d s p e c t r a l i n t e r e l e m e n t c o r r e c t i o n r o u t i n e s t h e n e b u l i z e r gas f l o w r a t e s h o u l d be t h e same from day-to-day ( 0.2%, a d d i t i o n a l d i l u t i o n may be r e q u i r e d t o p r e v e n t c l o g g i n g o f t h e e x t r a c t i o n and/or skimmer cones. If the d i r e c t addition procedure (Method A, Sect. 10.3) i s b e i n g used, add i n t e r n a l s t a n d a r d s and m i x . The sample i s now ready f o r a n a l y s i s . Because t h e e f f e c t s o f v a r i o u s m a t r i c e s on t h e s t a b i l i t y o f d i l u t e d samples cannot be c h a r a c t e r i z e d , a l l analyses should be performed as soon as p o s s i b l e a f t e r t h e completed p r e p a r a t i o n . 11.3 S o l i d Sample P r e p a r a t i o n - T o t a l Recoverable A n a l y t e s 11.3.1 F o r t h e d e t e r m i n a t i o n o f t o t a l r e c o v e r a b l e a n a l y t e s i n s o l i d samples, m i x t h e sample t h o r o u g h l y and t r a n s f e r a p o r t i o n ( > 20 g ) t o t a r e d w e i g h i n g d i s h , weigh t h e sample and r e c o r d t h e wet w e i g h t ( W W ) . ( F o r samples w i t h < 35% m o i s t u r e a 20 g portion i s sufficient. F o r samples w i t h m o i s t u r e > 35% a l a r g e r a l i q u o t 50-100 g i s r e q u i r e d . ) Dry t h e sample t o a c o n s t a n t w e i g h t a t 6OoC and r e c o r d t h e d r y w e i g h t (DW) f o r c a l c u l a t i o n o f p e r c e n t s o l i d s ( S e c t . 12.6). (The sample i s d r i e d a t 6OoC t o p r e v e n t t h e l o s s o f mercury and o t h e r p o s s i b l e v o l a t i l e m e t a l l i c compounds, t o f a c i l i t a t e s i e v i n g , and t o r e a d y t h e sample f o r g r i n d i n g . ) 11.3.2 To a c h i e v e homogeneity, s i e v e t h e d r i e d sample u s i n g a 5-mesh p o l y p r o p y l e n e s i e v e and g r i n d i n a m o r t a r and p e s t l e . (The s i e v e , m o r t a r and p e s t l e s h o u l d be c l e a n e d between samples.) From t h e d r i e d , ground m a t e r i a l weigh a c c u r a t e l y a r e p r e s e n t a t i v e 1.0 f 0.01 g a l i q u o t ( W ) o f t h e sample and t r a n s f e r t o a 250-mL P h i l l i p s beaker f o r a c i d e x t r a c t i o n . 11.3.3 To t h e beaker add 4 mL o f ( l t l ) HNO, and 10 mL o f ( 1 t 4 ) HC1. Cover t h e l i p o f t h e beaker w i t h a watch g l a s s . Place t h e beaker on a h o t p l a t e f o r r e f l u x e x t r a c t i o n o f t h e a n a l y t e s . The h o t p l a t e s h o u l d be l o c a t e d i n a fume hood and p r e v i o u s l y adjusted t o provide a r e f l u x temperature o f approximately 95OC. (See t h e f o l l o w i n g n o t e . )

NOTE:

F o r p r o p e r h e a t i n g a d j u s t t h e temperature c o n t r o l o f t h e h o t p l a t e such t h a t an uncovered G r i f f i n beaker c o n t a i n i n g 50 mL o f w a t e r p l a c e d i n t h e c e n t e r o f t h e h o t p l a t e can be m a i n t a i n e d a t a temperature a p p r o x i m a t e l y b u t no h i g h e r t h a n 85OC. (Once t h e beaker i s covered w i t h a watch g l a s s t h e t e m p e r a t u r e o f t h e w a t e r w i l l r i s e t o a p p r o x i m a t e l y 95OC.) A l s o , a b l o c k d i g e s t e r capable o f m a i n t a i n i n g a temperature o f 95OC

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and

equipped

with

250-mL

constricted

volumetric

d i g e s t i o n t u b e s may b e s u b s t i t u t e d f o r t h e hot plate

and conical beakers in the extraction step. 1 1 . 3 . 4 Heat the sample and gently reflux for 30 min.

Very slight boiling may occur, however vigorous boiling must be avoided to Some solution prevent loss of the HC1-H 0 azeotrope. evaporation will occur ( 3 to f m l ) .

11.3.5 Allow the sample to cool and quantitatively transfer the

extract to a 100-mL volumetric flask. Dilute to volume with reagent water, stopper and mix. 11.3.6 Allow the sample extract solution to stand overnight to

separate insoluble material or centrifuge a portion of the sample solution until clear. (If after centrifuging or standing overnight the extract solution contains suspended solids that would clog the nebulizer, a portion o f the extract solution may be filtered for their removal prior to analysis. However, care should be exercised to avoid potential cont ami nat i on from f i 1 trat i on. ) 11.3.7 Prior to analysis, adjust the chloride concentration

by pipetting 20 mL of the prepared solution into a 100-mL volumetric flask, dilute to volume with reagent water and mix. (If the dissolved solids in this solution are > 0.2%, additional dilution may be required to prevent clogging of the If the direct addition extraction and/or skimmer cones. procedure (Method A , Sect. 10.3) is being used, add internal standards and mix. The sample extract is now ready for analysis. Because the effects of various matrices on the stabi 1 i ty of di 1 uted samples cannot be characterized, a1 1 analyses should be performed as soon as possible after the completed preparation. NOTE:

Determine the percent solids in the sample for use in calculations and for reporting data on a dry weight basis.

11 4 Sample Analysis 1 1 . 4 . 1 For every new or unusual matrix, it is highly recommended that

a semi-quantitative analysis be carried out to screen the sample for elements at high concentration. Information gained from this may be used to prevent potential damage to the detector during sample analysis and to identify elements which may be higher than the linear range. Matrix screening may be carried out by using intelligent software, if available, or by diluting the sample by a factor o f 500 and analyzing in a semiquantitative mode. The sample should also be screened for background levels of all elements chosen for use as internal standards in order to prevent b i a s in the calculation of the analytical data. Revision 5 . 4

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11.4.2 I n i t i a t e i n s t r u m e n t o p e r a t i n g c o n f i g u r a t i o n . Tune and c a l i b r a t e the instrument f o r the analytes o f i n t e r e s t (Sect. 10.0).

11.4.3 E s t a b l i s h i n s t r u m e n t s o f t w a r e r u n procedures f o r q u a n t i t a t i v e analysis. For a l l sample analyses, a minimum o f t h r e e r e p l i c a t e i n t e g r a t i o n s a r e r e q u i r e d f o r d a t a a c q u i s i t i o n . Use t h e average o f t h e i n t e g r a t i o n s f o r d a t a r e p o r t i n g . 11.4.4 A l l masses which m i g h t a f f e c t d a t a q u a l i t y must be m o n i t o r e d during the a n a l y t i c a l run. A s a minimum, t h o s e masses p r e s c r i b e d i n T a b l e 4 must be m o n i t o r e d i n t h e same scan as i s used f o r t h e c o l l e c t i o n o f t h e d a t a . T h i s i n f o r m a t i o n s h o u l d be used t o c o r r e c t t h e d a t a f o r i d e n t i f i e d i n t e r f e r e n c e s . 11.4.5 D u r i n g t h e a n a l y s i s o f samples, t h e l a b o r a t o r y must comply w i t h t h e r e q u i r e d q u a l i t y c o n t r o l d e s c r i b e d i n S e c t i o n s 9.3 and 9.4. Only f o r t h e determination o f dissolved analytes o r t h e " d i r e c t a n a l y s i s " o f d r i n k i n g w a t e r w i t h t u r b i d i t y o f < 1 NTU i s t h e sample d i g e s t i o n s t e p o f t h e LRB,*LFB, and LFM n o t r e q u i r e d . 11.4.6 The r i n s e b l a n k s h o u l d be used t o f l u s h t h e system between samples. A l l o w s u f f i c i e n t t i m e t o remove t r a c e s o f t h e p r e v i o u s sample o r a minimum o f one m i n u t e ( S e c t . 4.1.5). Samples s h o u l d be a s p i r a t e d f o r 30 sec p r i o r t o t h e c o l l e c t i o n o f data. 11.4.7 Samples h a v i n g c o n c e n t r a t i o n s h i g h e r t h a n t h e e s t a b l i s h e d l i n e a r dynamic range s h o u l d be d i l u t e d i n t o range and r e a n a l y z e d . The sample s h o u l d f i r s t be analyzed f o r t h e t r a c e elements i n t h e sample, p r o t e c t i n g t h e d e t e c t o r f r o m t h e h i g h c o n c e n t r a t i o n elements, i f necessary, by t h e s e l e c t i o n o f a p p r o p r i a t e scanning windows. The sample s h o u l d t h e n be d i l u t e d f o r t h e d e t e r m i n a t i o n o f t h e r e m a i n i n g elements. A l t e r n a t i v e l y , t h e dynamic range may be a d j u s t e d by s e l e c t i n g an a1 t e r n a t i v e i s o t o p e o f l o w e r n a t u r a l abundance, p r o v i d e d qua1 i t y c o n t r o l d a t a f o r t h a t i s o t o p e have been e s t a b l i s h e d . The dynamic r a n g e must n o t be a d j u s t e d by a l t e r i n g i n s t r u m e n t c o n d i t i o n s t o an u n c h a r a c t e r i z e d s t a t e .

12.0 DATA ANALYSIS AND CALCULATIONS 12.1 Elemental e q u a t i o n s recommended f o r sample d a t a c a l c u l a t i o n s a r e l i s t e d i n T a b l e 5. Sample d a t a s h o u l d be r e p o r t e d i n u n i t s o f p g / L Do n o t f o r aqueous samples o r mg/kg dry w e i g h t f o r s o l i d samples. r e p o r t element c o n c e n t r a t i o n s below t h e determined MDL. 12.2 F o r d a t a v a l u e s l e s s t h a n t e n , two s i g n i f i c a n t f i g u r e s s h o u l d be used f o r r e p o r t i n g element c o n c e n t r a t i o n s . F o r d a t a v a l u e s g r e a t e r t h a n o r equal t o t e n , t h r e e s i g n i f i c a n t f i g u r e s s h o u l d be used. 12.3 F o r aqueous samples p r e p a r e d by t o t a l r e c o v e r a b l e procedure ( S e c t . 11.2), m u l t i p l y s o l u t i o n c o n c e n t r a t i o n s by t h e d i l u t i o n f a c t o r 1.25. I f a d d i t i o n a l d i l u t i o n s were made t o any samples or an aqueous sample Revision 5.4

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was prepared using the acid-mixture procedure described in Section 1 1 . 3 , the appropriate factor should be applied to the calculated sample concentrations. 12.4 For total recoverable analytes in solid samples (Sect. 11.3), round the solution analyte concentrations (pg/L in the analysis solution) as instructed in Section 12.2. Multiply the p/L concentrations in the analysis solution by the factor 0.005 to calculate the mg/L analyte concentration in the 100-mL extract solution. (If additional dilutions were made to any samples, the appropriate factor should be applied to Report calculate analyte concentrations in the extract solution.) the data up to three significant figures as mg/kg dry-weight basis unless specified otherwise by the program or data user. Calculate the concentration using the equation below: c x v Sample Conc. tmg/kg) dry-weight basis where: C

V W

= = =

=

~

W

Concentration in the extract (mg/L) Volume of extract (L, 100 mL = 0.1L) Weight of sample aliquot extracted (g x 0.001

=

kg)

Do not report analyte data below the estimated solids MDL or an adjusted MDL because of additional dilutions required to complete the analysis. 12.5 To report percent solids in solid samples (Sect. 11.3) calculate as foll ows :

DW % solids ( S )

where: DW

=

WW

=

NOTE:

=

-

ww

x 100

Sample weight (9) dried at 6OoC Sample weight (9) before drying

If the data user, program or laboratory requires that the reported percent sol ids be determined by drying at 105OC, repeat the procedure given in Section 11.3 using a separate portion ( > 20 g) of the sample and dry to constant weight at 1 03- 105OC.

12.6 Data values should be corrected for instrument drift or sample matrix induced interferences by the application of internal standardization. Corrections for characterized spectral interferences should be applied to the data. Chloride interference corrections should be made on all samples, regardless of the addition of hydrochloric acid, as the chloride ion is a common constituent of environmental samples. 12.7 If an element has more than one monitored isotope, examination of the concentration calculated for each isotope, or the isotope ratios, will provide useful information for the analyst in detecting a possible spectral interference. Consideration should therefore be given to f(f

200.8-29


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b o t h p r i m a r y and secondary i s o t o p e s i n t h e e v a l u a t i o n o f t h e element concentration. I n some cases, secondary i s o t o p e s may be l e s s s e n s i t i v e o r more prone t o i n t e r f e r e n c e s t h a n t h e p r i m a r y recommended i s o t o p e s , t h e r e f o r e d i f f e r e n c e s between t h e r e s u l t s do n o t n e c e s s a r i l y i n d i c a t e a problem w i t h d a t a c a l c u l a t e d f o r t h e p r i m a r y i s o t o p e s . 12.8 The QC d a t a o b t a i n e d d u r i n g t h e analyses p r o v i d e an i n d i c a t i o n o f t h e q u a l i t y o f t h e sample d a t a and s h o u l d be p r o v i d e d w i t h t h e sample results.

13.0 METHOD PERFORMANCE 13.1 I n s t r u m e n t o p e r a t i n g c o n d i t i o n s used f o r s i n g l e l a b o r a t o r y t e s t i n g o f t h e method a r e summarized i n Table 6 . T o t a l r e c o v e r a b l e d i g e s t i o n and " d i r e c t a n a l y s i s " MDLs d e t e r m i n e d u s i n g t h e procedure d e s c r i b e d i n Sect. 9 . 2 . 4 , a r e l i s t e d i n Table 7. 13.2 Data o b t a i n e d f r o m s i n g l e l a b o r a t o r y t e s t i n g o f t h e method a r e summarized i n T a b l e 9 f o r f i v e w a t e r samples r e p r e s e n t i n g d r i n k i n g w a t e r , s u r f a c e w a t e r , ground w a t e r and waste e f f l u e n t . Samples were For each p r e p a r e d u s i n g t h e procedure d e s c r i b e d i n Sect. 11.2. m a t r i x , f i v e r e p l i c a t e s were analyzed and t h e average o f t h e r e p l i c a t e s used f o r d e t e r m i n i n g t h e sample background c o n c e n t r a t i o n f o r each element. Two f u r t h e r p a i r s o f d u p l i c a t e s w e r e f o r t i f i e d a t d i f f e r e n t c o n c e n t r a t i o n l e v e l s . F o r each method element, t h e sample background c o n c e n t r a t i o n , mean p e r c e n t r e c o v e r y , t h e s t a n d a r d d e v i a t i o n o f t h e p e r c e n t r e c o v e r y and t h e r e l a t i v e p e r c e n t d i f f e r e n c e between t h e d u p l i c a t e f o r t i f i e d samples a r e l i s t e d i n Table 8. 13.3 Data o b t a i n e d f r o m s i n g l e l a b o r a t o r y t e s t i n g o f t h e method a r e summarized i n T a b l e 10 f o r t h r e e s o l i d samples c o n s i s t i n g o f SRM 1645 R i v e r Sediment, EPA Hazardous S o i l and EPA E l e c t r o p l a t i n g Sludge. Samples were p r e p a r e d u s i n g t h e procedure d e s c r i b e d i n Sect. 11.3. F o r each method element, t h e sample background c o n c e n t r a t i o n , mean p e r c e n t r e c o v e r y , t h e s t a n d a r d d e v i a t i o n o f t h e p e r c e n t r e c o v e r y and t h e r e l a t i v e p e r c e n t d i f f e r e n c e between t h e d u p l i c a t e f o r t i f i e d samples were d e t e r m i n e d as f o r Sect. 13.2. 13.4 Data o b t a i n e d f r o m s i n g l e l a b o r a t o r y t e s t i n g o f t h e method f o r d r i n k i n g w a t e r a n a l y s i s u s i n g t h e " d i r e c t a n a l y s i s " procedure (Sect. Three d r i n k i n g w a t e r samples o f 11.2.1) a r e g i v e n i n T a b l e 11. v a r y i n g hardness c o l l e c t e d f r o m Regions 4, 6, and 10 were f o r t i f i e d t o c o n t a i n 1 p g / L o f a l l m e t a l p r i m a r y contaminants, except selenium, w h i c h was added t o a c o n c e n t r a t i o n o f 20 p g / L . For each m a t r i x , f o u r r e p l i c a t e a1 i q u o t s were analyzed t o d e t e r m i n e t h e sample background c o n c e n t r a t i o n o f each a n a l y t e and f o u r f o r t i f i e d a1 i q u o t s were a n a l y z e d t o d e t e r m i n e mean p e r c e n t r e c o v e r y i n each m a t r i x . Listed i n t h e T a b l e 11 a r e t h e average mean p e r c e n t r e c o v e r y o f each a n a l y t e i n t h e t h r e e m a t r i c e s and t h e s t a n d a r d d e v i a t i o n o f t h e mean p e r c e n t recoveries. 13.5 L i s t e d i n T a b l e 12 a r e t h e r e g r e s s i o n e q u a t i o n s f o r p r e c i s i o n and b i a s developed f r o m t h e j o i n t USEPA/Association o f O f f i c i a l A n a l y t i c a l Chemists (AOAC) m u l t i l a b o r a t o r y v a l i d a t i o n s t u d y conducted on t h i s R e v i s i o n 5.4

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method. These equations were developed from data received from 13 laboratories on reagent water, drinking water and ground water. Listed in Tables 13 and 14, respectively, are the precision and recovery data from a wastewater digestate supplied to all laboratories and from a wastewater of the participant’s choice. For a complete review o f the study see reference 11. Section 16.0 of this method. 14.0 POLLUTION PREVENTION

14.1 Pollution prevention encompasses any technique that reduces or eliminates the quantity or toxicity of waste at the point of generation. Numerous opportunities for pollution prevention exist in laboratory operation. The EPA has established a preferred hierarchy of environmental management techniques that places pollution prevention as the management option of first choice. Whenever feasible, laboratory personnel should use pollution prevention techniques to address their waste generation. When wastes cannot be feasibly reduced at the source, the Agency recommends recycling as the next best option. 14.2 For information about pollution prevention that may be applicable to laboratories and research institutions, consult Less is Better: laboratory Chemical Management f o r Waste Reduction, available from the American Chemical Society’s Department of Government Relations and Science Policy, 1155 16th Street N.W., Washington D.C. 20036, (202)872-4477. 15.0 WASTE MANAGEMENT

15.1 The Environmental Protection Agency requires that laboratory waste management practices be conducted consistent with all applicable rules and regulations. The Agency urges laboratories to protect the air, water, and land by minimizing and controlling all releases from hoods and bench operations, complying with the letter and spirit of any sewer discharge permits and regulations, and by complying with all solid and hazardous waste regulations, particularly the hazardous waste identification rules and land disposal restrictions. For further information on waste management consult The W a s t e Management Manual for Laboratory Personne7, available from the American Chemical Society at the address listed in the Section 14.2. 16.0 REFERENCES

1.

Gray, A.L. and A. R. Date. Inductively Coupled Plasma Source Mass Spectrometry Using Continuum Flow Ion Extraction. Analyst 108 10331050, 1983.

2.

Houk, R . S . et al. Inductively Coupled Argon Plasma as an Ion Source for Mass Spectrometric Determination of Trace Elements. Anal Chem. 52 2283-2289, 1980.


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3.

Houk, R . S . , Mass Spectrometry o f I n d u c t i v e l y Coupled Plasmas. A n a l . Chem. 3 97A-l05A, 1986.

4.

Thompson, J.J. and R . S. Houk. A Study o f I n t e r n a l S t a n d a r d i z a t i o n i n I n d u c t i v e l y Coupled Plasma-Mass S p e c t r o m e t r y . A p p l . Spec. 41 801-806, 1987.

5.

Carcinogens - Working W i t h Carcinogens, Department o f H e a l t h , E d u c a t i o n , and W e l f a r e , P u b l i c H e a l t h S e r v i c e , Center f o r Disease C o n t r o l , N a t i o n a l I n s t i t u t e f o r O c c u p a t i o n a l S a f e t y and H e a l t h , P u b l i c a t i o n No. 77-206, Aug. 1977. A v a i l a b l e from t h e National T e c h n i c a l I n f o r m a t i o n S e r v i c e (NTIS) as PB-277256.

6.

OSHA S a f e t y and H e a l t h Standards, General I n d u s t r y , (29 CFR 1910), O c c u p a t i o n a l S a f e t y and H e a l t h A d m i n i s t r a t i o n , OSHA 2206, (Revised, January 1976).

7.

S a f e t y i n Academic Chemistry L a b o r a t o r i e s , American Chemical S o c i e t y Pub1 i c a t i o n , Committee on Chemical S a f e t y , 3 r d E d i t i o n , 1979.

8.

Proposed OSHA S a f e t y and H e a l t h Standards, L a b o r a t o r i e s , Occupational S a f e t y and H e a l t h A d m i n i s t r a t i o n , F e d e r a l R e g i s t e r , J u l y 24, 1986.

9.

American S o c i e t y f o r T e s t i n g and M a t e r i a l s . Standard S p e c i f i c a t i o n f o r Reagent Water, D1193-77. Annual Book o f ASTM Standards, V o l . 11.01. P h i l a d e l p h i a , PA, 1991.

10.

Code o f F e d e r a l R e g u l a t i o n s 40, Ch. 1, P t . 136 Appendix B.

11.

Longbottom, J.E. e t . a l . D e t e r m i n a t i o n o f Trace Elements i n Water by I n d u c t i v e l y Coupled P1 asma-Mass Spectrometry: C o l l a b o r a t i v e Study, J o u r n a l o f AOAC I n t e r n a t i o n a l 1004-1023, 1994.

12.

H i n n e r s , T.A., I n t e r f e r e n c e s i n ICP-MS by Bromine Species. Winter Conference on P1 asma S p e c t r o c h e m i s t r y , San Diego, CA, January, 10-15, 1994.

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17.0 TABLES. DIAGRAMS. FLOWCHARTS, AND VALIDATION DATA TABLE 1: ESTIMATED INSTRUMENT DETECTION L I M I T S

ESTIMATED IDLs (pg/L) ELEMENT

A1 uminum Ant imony Arsenic B a r i um B e r y l 1 ium Cadmi um Chromi um Cobalt Copper Lead Manganese Mercury Molybdenum Nickel Selenium S i 1v e r Thallium Thorium Urani urn Vanadium Zinc

RECOMMENDED ANALYTICAL MASS

27 123 75 137 9 111 52 59 63 206.207,208 55 202 98 60 82 107 205 232 238 51 66

SCANNING MODE’

SELECTIVE ION MONITORING MODE^

0.05 0.08 0.9 0.5 0.1 0.1 0.07 0.03 0.03 0.08 0.1

0.02 0.008 0.02 0.03 0.02 0.02 0.04 0.002. 0.004 0.015 0.007 0.2 0.005 0.07 1.3 0.004 0.014 0.005 0.005 0.006 0.07

n.a.

0.1 0.2 5

0.05 0.09 0.03 0.02 0.02 0.2

I n s t r u m e n t d e t e c t i o n 1 i m i t s ( 3 a ) e s t i m a t e d from seven rep1 i c a t e i n t e g r a t i o n s o f t h e b l a n k (1%v / v n i t r i c a c i d ) f o l l o w i n g c a l i b r a t i o n o f t h e i n s t r u m e n t w i t h t h r e e r e p l i c a t e i n t e g r a t i o n s o f a m u l t i - e l e m e n t standard.

1

I n s t r u m e n t o p e r a t i n g c o n d i t i o n s and d a t a a c q u i s i t i o n mode a r e g i v e n i n Table 6.

2 IDLsfidetermined u s i n s t a t e - o f - t h e - a r t

i n s t r u m e n t a t i o n (1994). Data f o r As, 77Se, and 8 9Se were a c q u i r e d u s i n g a d w e l l t i m e o f 4.096 sec w i t h 1500 area count p e r sec 83Kr p r e s e n t i n argon supply. A l l other d a t a were a c q u i r e d u s i n g a d w e l l t i m e o f 1.024 sec p e r AMU m o n i t o r e d .

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TABLE 2: COMMON MOLECULAR ION INTERFERENCES I N ICP-MS

BACKGROUND MOLECULAR IONS

Mol ecul a r I o n NH' OH' OH,'

',C C N' CO'

N,' N,H' NO'

NOH'

02' 0,H' 36ArH+

38ArH' "ArH'

co,' C0,H'

Arc', ArO' ArN' ArNH'

ArO' ArOH'

40Ar36Ar+ 40Ar38Ar' 40

Ar, a

+

Mass

15 17 18 24 26 28 28 29 30 31 32 33 37 39 41 44 45 52 54 55 56 57 76 78 80

Element Interference"

sc Cr Cr Mn

Se

Se Se

method elements o r i n t e r n a l standards a f f e c t e d by t h e m o l e c u l a r i o n s .

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TABLE 2 (Continued). MATRIX MOLECULAR IONS

Mol ecul ar Ion

Mass

'lBrH'

82 95 97 98

7 9 ~ r ~ +

BrO' BrOH' Ar'lBr'

121

CHLORIDE Mol ecul ar Ion

Mass

3 5 ~ 1 ~ + 3 5 ~ OH+ 1 3 7 1~O+ 3 7 ~ OH+ 1

51 52

53 54

Ar3'C1' Ar3?C1'

75 77

SULPHATE No1 ecul ar Ion

Mass

32su+

3 2 ~ ~ ~ 3 4 ~ ~ + 3 4 ~ ~ ~

so,',

s,'

+ +

48 49 50 51 64

El ement Interference Se Mo Mo Mo Sb

E 1 emen t Interference V Cr Cr Cr AS

Se

Element Interference V,Cr V

Zn

72 74

PHOSPHATE No1 ecul ar Ion

Mass

PO' POH'

47 48

PO,'

63

ArP'

71

GROUP I, I1 METALS Mol ecul ar Ion ArNa' ArK' ArCa'

Mass 63

El ement Interference

cu

Element Interference

cu

79 80


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TABLE 2 (Contl nued) . HATRXX MOLECULAR IONS

MATRIX OXIDES. Hol ecul ar Ion Ti0 ZrO MOO

*

Masses 62-66 106-112 108-116

Element Interference Ni,Cu,Zn Ag Y Cd Cd

Oxide i n t e r f e r e n c e s w i l l normally be very small and w i l l o n l y impact t h e method elements when present a t r e l a t i v e l y h i g h concentrations. Some examples o f m a t r i x oxides are l i s t e d o f which t h e analyst should be aware. It i s recommended t h a t T i and Z r isotopes are monitored i n s o l i d waste samples, which are l i k e l y t o c o n t a i n h i g h l e v e l s o f these elements. Mo i s monitored as a method analyte.

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Methods for the Determination TABLE 3: INTERNAL STANDARDS AND LIMITATIONS OF USE

I n t e r n a l Standard 6Li t h i um Scandi urn Yttrium Rhodi um I n d i urn T erb i urn H o l m i um Lut eti u m Bismuth

Mass

6 45 89 103

115 159 165

Possible L i m i t a t i o n a polyatomic i o n i n t e r f e r e n c e a,b i s o b a r i c i n t e r f e r e n c e by Sn

175

209

a

a May be present i n environmental samples. b I n Some instruments Y t t r i u m may form measurable amounts o f YO' (105 amu)and YOH (106 amu). I f t h i s i s t h e case, care should be taken i n t h e use o f t h e cadmium elemental c o r r e c t i o n equation.

I n t e r n a l standards recommended f o r use w i t h t h i s method are shown i n b o l d face. Prepa ra ti o n procedures f o r these are i n c l u d e d i n Section 7.3.

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TABLE 4: RECOMMENDED ANALYTICAL ISOTOPES AND ADDITIONAL MASSES WHICH MUST BE MONITORED

Isotope

Element of I n t e r e s t

27

A1 umi num Antimony Arsenic B a r i um B e r y l 1 iurn Cadmi urn Chromi urn Cobalt Copper Lead Manganese Molybdenum Nickel Sel en iurn S i 1v e r T h a l l ium T h o r i urn Uran ium Vanadi um

121,123

75 135,137 9 106,108,JJl, 114 52 ,53 59 63,65 206,207,208 -55 95,97,98 60,62 77,g 107,109 203,205

232 238 51 66,67,68 83 99 105 118

Zinc Krypton Rut hen iurn Palladium Tin

NOTE: I s o t o p e s recommended f o r a n a l y t i c a l d e t e r m i n a t i o n a r e under1 ined.

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126

Methods for the Determination TABLE 5: RECOMMENDED ELEMENTAL EQUATIONS FOR DATA CALCULATIONS

Element

Elemental Equation

A1

(1 .ooo) (27c)

Sb

(~.ooo)(~~~c)

As

(l.000)(75C)-(3.127)[(nC)-(0.815)(82C)]

Ba

(1 .OOO) (137c)

Be

(1.000)(9c)

Cd

(1 .OOO) (l”C)-( 1.073) [ (lO8C)-(0 .712) ( 106C)]

Cr

(1.ooo) (52c)

co

( 1.000) (59c)

cu

(1.000)(9)

Pb

(1.000) (206c)t( 1 .OOO) (207c)t( 1 .OOO) (208c)

Mn

( 1.000)( 55c)

Mo

( 1 000) ( 98C) - ( 0.146) (99C)

Ni

(1.000)(60c)

Se

( 1 * 000)(82c)

Ag

(1.000)( ‘07C)

T1

(1.000)(205c)

Th

(~.ooo)(~~~c)

U

(1.000)(~~~c)

V

(1.000)(51c)- (3.127)[ (53c)- (0.113) (52c)3

Zn

(1 .OOO) p c )

.

Revision 5.4

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TABLE 5 (Continued) ~~~~~

~~

~~

INTERNAL STANDARDS Element

Elemental Equation

Bi

(1 .ooo) (*09c)

In

(1 .OOO) ("*C)- (0.016)('"C)

sc

(1.ooo)

Tb

(~.ooo)(~~~c)

Y

(1.000)(89c)

(45c)

C - calibration blank subtracted counts at specified mass. (1) - borrection for chloride interference with adjustment for Se. ArCl 75/77 ratio may be determined from the reagent blank. Isobaric mass 8 2 must be from Se only and not BrH'. (2) - correction f+or MOO interference. Isobaric mass 106 must be from Cd only not ZrO . An additional isobaric elemental correction should be made if palladium i s present. (3) - in 0.4% v/v HC1, the background from ClOH will normally be small. However the contribution may be estimated from the reagent blank. Isobaric mass must be from Cr only not Arc'. (4) - allowance for isotopic variability o f lead isotopes. (5) - isobaric elemental correction for ruthenium. (6) - some argon supplies contain krypton as an impurity. Selenium is corrected for 82Kr by background subtraction. (7) - correction for chloride interference with adjustment for 'kr. C10 51/53 ratio may be determined from the reagent blank. Isobaric mass 52 must be from Cr only not Arc'. (8) - isobaric elemental correction for tin.


128


TABLE 6: INSTRUMENT OPERATING CONDITIONS FOR PRECISION AND RECOVERY DATA'

Instrument P1 asma f o r w a r d power Coolant f l o w r a t e Auxiliary flow rate Nebulizer flow r a t e S o l u t i o n uptake r a t e Spray chamber t e m p e r a t u r e

VG PlasmaQuad Type I 1 . 3 5 kW 13.5 L/min 0.6 L/min 0.78 L/min 0.6 mL/min 15°C

Data A c q u i s i t i o n D e t e c t o r mode Replicate integrations Mass range Dwell t i m e Number o f MCA channels Number o f scan sweeps Total acquisition time

Pul se c o u n t i n g 3 8 - 240 amu 3 2 0 ps 2048 85 3 minutes p e r sample

1 The d e s c r i b e d i n s t r u m e n t and o p e r a t i n g c o n d i t i o n s were used t o d e t e r m i n e t h e scanning mode MDL d a t a l i s t e d i n T a b l e 7 and t h e p r e c i s i o n and r e c o v e r y d a t a g i v e n i n Tables 9 and 10.

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TABLE 7: METHOD DETECTION L I M I T S

'

W

SCANNING MODE' TOTAL RECOVERABLE AQUEOUS SOLIDS p g~/ L ~ mglkg

27

A1

123

Sb

1 .o 0.4

Ts

As

137

'11 52 59

63

~

SELECTIVE O I N MONITORING MODE^ TOTAL RECOVERABLE DIRECT ANALYSIS' AQUEOUS AQUEOUS ~ P9IL ~ ~ M I L~

1.7

1.4

0.4 0.2 0.6

0.04 0.4

0.04 0.02 0.1

Ba Be Cd

0.8 0.3 0.5

0.4 0.1 0.2

0.04 0.02 0.03

0.04 0.03 0.03

Cr co

0.9 0.09 0.5

0.4 0.04 0.2

0.08 0.004 0.02

0.08 0.003 0.01

0.6 0.1

0.3 0.05

0.05 0.02

n.a.

n.a.

n.a.

0.02 0.04 0.2

cu

206,207,208 pb 55 202

Mn Hg

98

Mo Ni Se

0.3 0.5 7.9

0.1 0.2 3.2

0.01 0.06 2.1

0.01 0.03 0.5

lo7

Ag

205

232

T1 Th

0.1 0.3 0.1

0.05 0.1 0.05

0.005 0.02 0.02

0.005 0.01 0.01

238

u

51

v

0.1 2.5 1.8

0.05 1.0 0.7

0.01 0.9 0.1

0.01 0.05 0.2

6o 82

66

Zn

-~ 1 Data acquisition mode given in Table 6. Total recoverable MDL concentrations are computed for original matrix with allowance for sample dilution during preparation. Listed MDLs for solids calculated from determined aqueous MDLs. 2 &DLs determined using state-of-the-art instrumentation (1994). Data for A s , nSe, and "Se were acquired using a dwell time of 4.096 sec with 1500

area count per sec 83Kr present in argon supply. All other data were acquired using a dwell time of 1.024 sec per AMU monitored. 3

MDLs were determined from analysis of 7 undigested aqueous sample aliquots.

n.a.- not applicable. Total recoverable digestion not suitable for organomercury compounds. Revision 5.4 May 1994

130

Methods for the Determination TABLE 8: ACCEPTANCE LIMITS FOR QC CHECK SAMPLE

METHOD PERFORMANCE ( F g l L ) ’

ELEMENT

Aluminum Antimony Arsenic Barium Beryllium Cadmium Chromium Cobalt Copper Lead Manganese Molybdenum Nickel Selenium Silver Thallium Thorium Uranium Vanadium Zinc

1

*3 4

5

QC Check Sample Conc.

100 100

100 100 100 100 100

100 100 100 100 100 100 100 100 100 100 100

100 100

Average Recovery

100.4 99.9 101.6 99.7 105.9 100.8 102.3 97.7 100.3 104.0 98.3

101 .o 100.1 103.5 101 .I 98.5 101.4 102.6 100.3 105.1

Standard Deviation’ (S,)

5.49 2.40 3.66 2.64 4.13 2.32 3.91 2.66 2.11 3.42 2.71 2.21 2.10 5.67 3.29 2.79 2.60 2.82 3.26 4.57

Acceptance Limits3 flg/L

84-117 93-107 91-113 92-108 88-11 24 94-1 08 91-114 90-I 06 94-I 07 94-114 90-1 06 94-1 08 94-106 86-121 91-Ill5 90-1 07 94-109 94-11 1 90-110 91-119

Method performance characteristics calculated using regression equations from collaborative study, reference 1 1. Single-analyst standard deviation, S,. Acceptance limits calculated as average recovery +3 standard deviations. Acceptance limits centered at 100% recovery. Statistics estimated from summary statistics at 48 and 64 pg/L.

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TABLE 9 : PRECISION AND RECOVERY DATA I N AQUEOUS MATRICES DRINKING WATER

Sample Element Concn. (uq/LI

A1 Sb As Ba

Be Cd Cr co cu Pb Mn Mo Ni Se Ag T1

Th U V Zn

S(R) RPD

50 mg/kg s h o u l d be t r e a t e d i n a s i m i l a r manner.

1.7

Method d e t e c t i o n l i m i t s and i n s t r u m e n t o p e r a t i n g c o n d i t i o n s f o r t h e a p p l i c a b l e elements a r e l i s t e d i n T a b l e 2. These a r e i n t e n d e d as a g u i d e and a r e t y p i c a l o f a system o p t i m i z e d f o r t h e element employing commercial i n s t r u m e n t a t i o n . However, a c t u a l method d e t e c t i o n l i m i t s and l i n e a r w o r k i n g ranges w i l l be dependent on t h e sample m a t r i x , i n s t r u m e n t a t i o n and s e l e c t e d o p e r a t i n g c o n d i t i o n s .

1.8

The s e n s i t i v i t y and l i m i t e d l i n e a r dynamic range (LDR) o f GFAA o f t e n i m p l i e s t h e need t o d i l u t e a sample p r i o r t o a n a l y s i s . The a c t u a l magnitude o f t h e d i l u t i o n as w e l l as t h e c l e a n l i n e s s o f t h e labware used t o p e r f o r m t h e d i l u t i o n can d r a m a t i c a l l y i n f l u e n c e t h e q u a l i t y o f t h e a n a l y t i c a l r e s u l t s . T h e r e f o r e , samples t y p e s r e q u i r i n g l a r g e d i l u t i o n s (>50:1) s h o u l d be analyzed by an a n o t h e r approved t e s t procedure w h i c h has a l a r g e r LDR o r which i s i n h e r e n t l y l e s s s e n s i t i v e t h a n GFAA.

1.9

Users o f t h e method d a t a s h o u l d s t a t e t h e d a t a - q u a l i t y o b j e c t i v e s p r i o r t o a n a l y s i s . Users o f t h e method must document and have on f i l e t h e r e q u i r e d i n i t i a l d e m o n s t r a t i o n performance d a t a d e s c r i b e d i n S e c t i o n 9 . 2 p r i o r t o u s i n g t h e method f o r a n a l y s i s . Revision 2.2 Hay 1994

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OF METHOD

2.1

An aliquot of a well mixed, homogeneous aqueous or solid sample is accurately weighed or measured for sample processing. For total recoverable analysis of a solid or an aqueous sample containing undissolved material, analytes are first solubilized by gentle refluxing with nitric and hydrochloric acids. After cooling, the sample is made up to volume, is mixed and centrifuged or allowed to settle overnight prior to analysis. For the determination of dissolved analytes in a filtered aqueous sample aliquot, or for the "direct analysis" total recoverable determination of analytes where sample turbidity i s < 1 NTU, the sample is made ready for analysis by the appropriate addition of nitric acid, and then diluted to a predetermined volume and mixed before analysis.

2.2

The analytes listed in this method are determined by stabilized temperature platform graphite furnace atomic absorption (STPGFAA). In STPGFAA, the sample and the matrix modifier are first pipetted onto the platform or a device which provides delayed atomization. The furnace chamber is then purged with a continuous flow of a premixed gas (95% argon - 5% hydrogen) and the sample is dried at a relatively low temperature (about 120°C) to avoid spattering. Once dried, the sample is pretreated in a char or ashing step which is designed to minimize the interference effects caused by the concomitant sample matrix. After the char step the furnace is allowed to cool prior to atomization. The atomization cycle is characterized by rapid heating of the furnace to a temperature where the metal (analyte) is atomized from the pyrolytic graphite surface into a stopped gas flow atmosphere of argon containing 5% hydrogen. (Only selenium is determined in an atmosphere of high purity argon.) The resulting atomic cloud absorbs the element specific atomic emission produced by a hollow cathode lamp (HCL) or an electrodeless discharge lamp (EDL). Following analysis the furnace is subjected to a cleanout period of high temperature and continuous argon flow. Because the resulting absorbance usually has a nonspecific component associated with the actual analyte absorbance, an instrumental background correction device is required to subtract from the total signal the component which is nonspecific to the analyte. In the absence of interferences, the background corrected absorbance is directly related to the concentration of the analyte. Interferences relating to STPGFAA (Section 4 . 0 ) must be recognized and corrected. Suppressions or enhancements of instrument response caused by the sample matrix must be corrected by the method of standard addition (Section 1 1 . 5 ) .

DEFINITIONS 3.1

Calibration Blank - A volume of reagent water acidified with the same acid matrix as in the calibration standards. The calibration blank is a zero standard and is used to auto-zero the AA instrument (Sect. 7 . 1 0 . 1 ) .

3.2

Calibration Standard (CAL) - A solution prepared from the dilution of stock standard solutions. The CAL solutions are used to Revision 2.2 May 1994

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Methods for the Determination c a l ib r a t e t h e i n s t r u m e n t concentration (Sect. 7.9).

response

with

respect

to

analyte

3.3

D i s s o l v e d A n a l y t e - The c o n c e n t r a t i o n o f a n a l y t e i n an aqueous sample t h a t w i l l pass t h r o u g h a 0.45-pm membrane f i l t e r assembly p r i o r t o sample a c i d i f i c a t i o n ( S e c t . 1 1 . 1 ) .

3.4

F i e l d Reagent B l a n k (FRB) - An a l i q u o t o f r e a g e n t w a t e r o r o t h e r b l a n k m a t r i x t h a t i s p l a c e d i n a sample c o n t a i n e r i n t h e l a b o r a t o r y and t r e a t e d as a sample i n a l l r e s p e c t s , i n c l u d i n g shipment t o t h e sampling s i t e , exposure t o t h e sampling s i t e c o n d i t i o n s , s t o r a g e , p r e s e r v a t i o n , and a l l a n a l y t i c a l procedures. The purpose o f t h e FRB i s t o d e t e r m i n e i f method a n a l y t e s o r o t h e r i n t e r f e r e n c e s a r e p r e s e n t i n t h e f i e l d environment ( S e c t 8 . 5 ) .

3.5

I n s t r u m e n t D e t e c t i o n L i m i t (IDL) - The c o n c e n t r a t i o n e q u i v a l e n t t o t h e a n a l y t e s i g n a l w h i c h i s equal t o t h r e e t i m e s t h e s t a n d a r d d e v i a t i o n o f a s e r i e s o f t e n r e p l i c a t e measurements o f t h e c a l i b r a t i o n b l a n k s i g n a l a t t h e same wavelength.

3.6

I n s t r u m e n t Performance Check ( I P C ) S o l u t i o n - A s o l u t i o n o f method a n a l y t e s , used t o e v a l u a t e t h e performance o f t h e i n s t r u m e n t system w i t h r e s p e c t t o a d e f i n e d s e t o f method c r i t e r i a ( S e c t s . 7.11 & 9.3.4).

3.7

L a b o r a t o r y D u p l i c a t e s (LD1 and LD2) - Two a l i q u o t s o f t h e same sample t a k e n i n t h e l a b o r a t o r y and analyzed s e p a r a t e l y w i t h i d e n t i c a l procedures. Analyses o f LD1 and LD2 i n d i c a t e s p r e c i s i o n a s s o c i a t e d w i t h 1 a b o r a t o r y procedures, b u t n o t w i t h sample c o l l e c t i o n , p r e s e r v a t i o n , o r s t o r a g e procedures.

3.8

L a b o r a t o r y F o r t i f i e d B l a n k (LFB) - An a l i q u o t o f LRB t o which known q u a n t i t i e s o f t h e method a n a l y t e s a r e added i n t h e l a b o r a t o r y . The LFB i s a n a l y z e d e x a c t l y l i k e a sample, and i t s purpose i s t o d e t e r m i n e whether t h e methodology i s i n c o n t r o l and whether t h e 1 a b o r a t o r y i s capable o f making a c c u r a t e and p r e c i s e measurements ( S e c t s . 7.10.3 & 9 . 3 . 2 ) .

3.9

L a b o r a t o r y F o r t i f i e d Sample M a t r i x (LFM) - An a l i q u o t o f an e n v i r o n m e n t a l sample t o which known q u a n t i t i e s o f t h e method a n a l y t e s a r e added i n t h e l a b o r a t o r y . The LFM i s analyzed e x a c t l y l i k e a sample, and i t s purpose i s t o d e t e r m i n e whether t h e sample m a t r i x c o n t r i b u t e s b i a s t o t h e a n a l y t i c a l r e s u l t s . The background c o n c e n t r a t i o n s o f t h e a n a l y t e s i n t h e sample m a t r i x must be determined i n a s e p a r a t e a l i q u o t and t h e measured v a l u e s i n t h e LFM c o r r e c t e d f o r background c o n c e n t r a t i o n s ( S e c t . 9 . 4 ) .

3.10

L a b o r a t o r y Reagent B l a n k (LRB) - An a l i q u o t o f r e a g e n t w a t e r o r o t h e r b l a n k m a t r i c e s t h a t a r e t r e a t e d e x a c t l y as a sample i n c l u d i n g exposure t o a l l glassware, equipment, s o l v e n t s , r e a g e n t s , and i n t e r n a l standards t h a t a r e used w i t h o t h e r samples. The LRB i s used t o d e t e r m i n e i f method a n a l y t e s o r o t h e r i n t e r f e r e n c e s a r e p r e s e n t i n t h e 1a b o r a t o r y environment, r e a g e n t s , o r apparatus ( S e c t s . 7.10.2 & 9 . 3 . 1 ) . Revision 2.2 Ray 1994

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3.11

Linear Dynamic Range (LDR) - The concentration range over which the instrument response t o an analyte is linear (Sect. 9.2.2).

3.12

Matrix Modifier - A substance added to the graphite furnace along with the sample in order to minimize the interference effects by selective volatilization of either analyte or matrix components.

3.13

Method Detection Limit (MDL) - The minimum concentration of an analyte that can be identified, measured, and reported with 99% confidence that the analyte concentration is greater than zero (Sect. 9.2.4 and Table 2 ) .

3.14

Quality Control Sample (QCS) - A solution of method analytes of known concentrations which is used to fortify an aliquot of LRB or sample matrix. The QCS is obtained from a source external to the laboratory and different from the source of calibration standards. It i s used to check either laboratory or instrument performance (Sects. 7.12 & 9 . 2 . 3 ) .

3.15

Solid Sample - For the purpose of this method, a sample taken from material classified as either soil, sediment or sludge.

3.16

Standard Addition - The addition of a known amount of analyte to the sample in order to determine the relative response of the detector to an analyte within the sample matrix. The relative response is then used to assess either an operative matrix effect or the sample analyte concentration (Sects. 9 . 5 . 1 & 11.5).

3.17

Stock Standard Solution - A concentrated solution containing one or more method analytes prepared in the laboratory using assayed reference materials or purchased from a reputable commercial source (Sect. 7.8).

3.18

Total Recoverable Analyte - The concentration of analyte determined to be in either a solid sample or an unfiltered aqueous sample following treatment by refluxing with hot dilute mineral acid(s) as specified in the method (Sects. 11.2 & 11.3).

3.19

Water Sample - For the purpose of this method, a sample taken from one of the following sources: drinking, surface, ground, storm runoff, industrial or domestic wastewater.

INTERFERENCES 4.1

Several interference sources may cause inaccuracies in the determination of trace elements by GFAA. These interferences can be classified into three major subdivisions, namely spectral, matrix, and memory.

4.2

Spectral interferences are caused by the resulting absorbance of light by a molecule or atom which is not the analyte of interest or emission from black body radiation. 4 . 2 . 1 Spectral interferences caused by an element only occur if


152

Methods for the Determination there is a spectral overlap between the wavelength of the interfering element and the analyte of interest. Fortunately, this type of interference is relatively uncommon in STPGFAA because of the narrow atomic line widths associated with In addition, the use of appropriate furnace STPGFAA. temperature programs and high spectral purity lamps as light sources can minimize the possibility of this type o f interference. However, mol ecul ar absorbances can span several hundred nanometers producing broadband spectral interferences. This type of interference is far more common in STPGFAA. The use of matrix modifiers, selective volatilization, and background correctors are all attempts to eliminate unwanted nonspecific absorbance. The nonspecific component of the total absorbance can vary considerably from sample type to sample type. Therefore, the effectiveness of a particular background correction device may vary depending on the actual analyte wavelength used as well as the nature and magnitude o f the interference. The background correction device to be used with this method is not specified, however, it must provide an analytical condition that is not subject to the occurring interelement spectral interferences of palladium on copper, iron on selenium, and aluminum on arsenic. 4.2.2 Spectral interferences are also caused by the emissions from black body radiation produced during the atomization furnace cycle. This black body emission reaches the photomultiplier tube, producing erroneous results. The magnitude of this interference can be minimized by proper furnace tube a1 ignment and monochromator design. In addition, atomization temperatures which adequately volatilize the analyte of interest without producing unnecessary black body radiation can he1 p reduce unwanted background emission during analysis. 4.3

Matrix interferences are caused by sample components which inhibit the formation of free atomic analyte atoms during the atomization CYC e. 4.3 1 Matrix interferences can be of a chemical or physical nature. In this method the use of a delayed atomization device which provides stabilized temperatures is required. These devices provide an environment which is more conducive to the formation of free analyte atoms and thereby minimize this type of interference. This type of interference can be detected by analyzing the sample plus a sample aliquot fortified with a known concentration of the analyte. If the determined concentration of the analyte addition is outside a designated range, a possible matrix effect should be suspected (Sect. 9.4.3). 4.3.2 The use o f nitric acid is preferred for GFAA analyses in order to minimize vapor state anionic chemical interferences, however, in this method hydrochloric acid is required to maintain stability in solutions containing antimony and silver. When hydrochloric acid is used, the chloride ion


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vapor state interferences must be reduced using an appropriate matrix modifier. In this method a combination modifier of palladium, magnesium nitrate and a hydrogen(5%)-argon(95%) gas mixture is used for this purpose. The effects and benefits of using this modifier are discussed in detail in reference 2 . of Section 16.0. Listed in Section 4 . 4 are some typical observed effects when using this modifier. 4. 4

Specific Element Interferences Antimyy: Antimony suffers from an interference produced by K2S0,. In the absence of hydrogen in the char cycle (13OO0C), K SO, produces a relatively high ( 1 . 2 abs) background absorbance which can produce a false signal, even with Zeeman background correction. However, this background level can be dramatically reduced ( 0 . 1 abs) by the use of a hydrogenlargon gas mixture in the char step. This reduction in background is strongly influenced by the temperature of the char step. NOTE: The actual furnace temperature may vary from instrument t o instrument. Therefore, the actual furnace

temperataure should be determined on an individual basi s . Aluminum: The palladium matrix modifier may have elevated levels of A1 which will cause elevated blank absorbances. Arsenic: The HC1 present from the digestion procedure can influence the sensitivity for A s . 20 pL of a 1%HC1 solution with Pd used as a modifier results in a 20% loss in sensitivity relative to the analyte in a 1% HNO, solution. Unfortunately, the use of Pd/Mg/H? as a modifier does not significantly reduce this suppression, and therefore, it is imperative that each sample and calibration standard a1 i ke contain the same HC1 concentration. 2 Cadmium: The HC1 present from the digestion procedure can influence the sensitivity for Cd. 20 pL of a 1% HC1 solution with Pd used as a modifier results in a 80% loss in sensitivity relative t o the analyte in a’ 1% HNO, solution. The use of Pd/Mg/H, as a matrix modifier reduces this suppression to less than lo%., Lead: The HC1 present from the digestion procedure can influence the sensitivity for Pb. 20 pL of a 1% HC1 solution with Pd used as a modifier results in a 75% loss in sensitivity relative to the analyte response in a 1% HNO, solution. The use o f Pd/Mg/H, as2a matrix modifier reduces this suppression to less than 10%. Selenium: Iron has been shown :t suppress Se response with continuum background correction. In addition, the use of hydrogen as a purge gas during the dry and char steps can cause a suppression in Se response if not purged from the Revision 2.2 Hay

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Methods for the Determination furnace p r i o r t o atomization. S i l v e r : The p a l l a d i u m used i n t h e m o d i f i e r p r e p a r a t i o n may have e l e v a t e d l e v e l s o f Ag w h i c h w i l l cause e l e v a t e d b l a n k absorbances. T h a l l i u m : The HC1 p r e s e n t f r o m t h e d i g e s t i o n procedure can i n f l u e n c e t h e s e n s i t i v i t y f o r T1. 20 pL o f a 1% HC1 s o l u t i o n w i t h Pd used as a m o d i f i e r r e s u l t s i n a 90% l o s s i n s e n s i t i v i t y r e l a t i v e t o t h e a n a l y t e i n a 1% HNO, s o l u t i o n . The use o f Pd/Mg/H, as a m a t r i x m o d i f i e r reduces t h i s s u p p r e s s i o n . t o l e s s t h a n lo%.'

4.5

5.0

Memory i n t e r f e r e n c e s r e s u l t f r o m a n a l y z i n g a sample c o n t a i n i n g a h i g h c o n c e n t r a t i o n o f an element ( t y p i c a l l y a h i g h a t o m i z a t i o n t e m p e r a t u r e element) which cannot be removed q u a n t i t a t i v e l y i n one complete s e t o f f u r n a c e s t e p s . The a n a l y t e which remains i n t h e f u r n a c e can produce f a l s e p o s i t i v e s i g n a l s on subsequent sample(s). Therefore, t h e analyst should e s t a b l i s h t h e analyte concentration which can be i n j e c t e d i n t o t h e f u r n a c e and adequately removed i n one complete s e t o f f u r n a c e c y c l e s . I f t h i s c o n c e n t r a t i o n i s exceeded, t h e sample s h o u l d be d i l u t e d and a b l a n k analyzed t o assure t h e memory e f f e c t has been e l i m i n a t e d b e f o r e r e a n a l y z i n g t h e d i l u t e d sample.

SAFETY

5.1

The t o x i c i t y o r c a r c i n o g e n i c i t y o f each r e a g e n t used i n t h i s method have n o t been f u l l y e s t a b l i s h e d . Each chemical s h o u l d be regarded as a p o t e n t i a l h e a l t h hazard and exposure t o t h e s e compounds should be as l o w as r e a s o n a b l y a c h i e v a b l e . Each l a b o r a t o r y i s r e s p o n s i b l e f o r m a i n t a i n i n g a c u r r e n t awareness f i l e o f OSHA r e g u l a t i o n s r e g a r d i r 9 t h e safe handling o f t h e chemicals s p e c i f i e d i n t h i s method. A r e f e r e n c e f i l e o f m a t e r i a l d a t a h a n d l i n g sheets should a l s o be made a v a i l a b l e t o a l l personnel i n v o l v e d i n t h e chemical a n a l y s i s . S p e c i f i c a l l y , c o n c e n t r a t e d n i t r i c and h y d r o c h l o r i c a c i d s p r e s e n t v a r i o u s hazards and a r e m o d e r a t e l y t o x i c and e x t r e m e l y i r r i t a t i n g t o s k i n and mucus membranes. Use t h e s e r e a g e n t s i n a fume hood whenever p o s s i b l e and i f eye o r s k i n c o n t a c t occurs, f l u s h w i t h l a r g e volumes o f w a t e r . Always wear s a f e t y g l a s s e s o r a s h i e l d f o r eye p r o t e c t i o n , p r o t e c t i v e c l o t h i n g and observe p r o p e r m i x i n g when w o r k i n g w i t h t h e s e r e a g e n t s .

5.2

The a c i d i f i c a t i o n o f samples c o n t a i n i n g r e a c t i v e m a t e r i a l s may r e s u l t i n t h e r e l e a s e o f t o x i c gases, such as c y a n i d e s o r s u l f i d e s . A c i d i f i c a t i o n o f samples s h o u l d be done i n a fume hood.

5.3


5.4

The g r a p h i t e t u b e d u r i n g a t o m i z a t i o n e m i t s i n t e n s e UV r a d i a t i o n . S u i t a b l e p r e c a u t i o n s s h o u l d be t a k e n t o p r o t e c t personnel f r o m such a hazard. Revision 2.2 May 1994

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5.5

The use o f t h e argonlhydrogen gas m i x t u r e d u r i n g t h e d r y and c h a r Therefore, steps may e v o l v e a c o n s i d e r a b l e amount o f HC1 gas. adequate v e n t i l a t i o n i s r e q u i r e d .

5.6

I t i s t h e r e s p o n s i b i l i t y o f t h e u s e r o f t h i s method t o comply w i t h r e l e v a n t d i s p o s a l and waste r e g u l a t i o n s . F o r guidance see S e c t i o n s 14.0 and 15.0.

EOUIPMENT AND SUPPLIES 6.1

G r a p h i t e Furnace Atomic Absorbance Spectrophotometer 6 . 1 . 1 The GFAA s p e c t r o m e t e r must be capable o f programmed h e a t i n g o f t h e g r a p h i t e t u b e and t h e a s s o c i a t e d d e l a y e d a t o m i z a t i o n device. The i n s t r u m e n t must be equipped w i t h an adequate background c o r r e c t i o n d e v i c e capable o f removing u n d e s i r a b l e n o n - s p e c i f i c absorbance o v e r t h e s p e c t r a l r e g i o n o f i n t e r e s t and p r o v i d e an a n a l y t i c a l c o n d i t i o n n o t s u b j e c t t o t h e occurrence o f interelement spectral overlap interferences. The f u r n a c e d e v i c e must be capable o f u t i l i z i n g an a l t e r n a t e gas s u p p l y d u r i n g s p e c i f i e d c y c l e s o f t h e a n a l y s i s . The c a p a b i l i t y t o record r e l a t i v e l y f a s t (< 1 s) transient signals In and e v a l u a t e d a t a on a peak area b a s i s i s p r e f e r r e d . a d d i t i o n , a r e c i r c u l a t i n g r e f r i g e r a t i o n b a t h i s recommended f o r improved r e p r o d u c i b i l i t y o f f u r n a c e temperatures. 6 . 1 . 2 S i n g l e element h o l l o w cathode lamps o r s i n g l e element e l e c t r o d e l e s s d i s c h a r g e lamps a l o n g w i t h t h e a s s o c i a t e d power suppl ies

.

6 . 1 . 3 Argon gas s u p p l y ( h i g h - p u r i t y grade, 99.99%) f o r use d u r i n g t h e a t o m i z a t i o n o f selenium, f o r s h e a t h i n g t h e f u r n a c e t u b e when i n o p e r a t i o n , and d u r i n g f u r n a c e c l e a n o u t . 6 . 1 . 4 A l t e r n a t e gas m i x t u r e (hydrogen 5% - argon 95%) f o r use as a c o n t i n u o u s gas f l o w environment d u r i n g t h e dry and c h a r furnace cycles. 6 . 1 . 5 Autosampler c a p a b l e o f a d d i n g m a t r i x m o d i f i e r s o l u t i o n s t o t h e f u r n a c e , a s i n g l e a d d i t i o n o f a n a l y t e , and c o m p l e t i n g methods o f s t a n d a r d a d d i t i o n s when r e q u i r e d .

6.2

A n a l y t i c a l balance, w i t h c a p a b i l i t y t o measure t o 0 . 1 mg, f o r use i n w e i g h i n g s o l i d s , f o r p r e p a r i n g standards, and f o r d e t e r n l i n i n g dissolved solids i n digests o r extracts.

6.3

A temperature a d j u s t a b l e h o t t e m p e r a t u r e o f 95OC.

6.4

A t e m p e r a t u r e a d j u s t a b l e b l o c k d i g e s t e r capable o f (optional) m a i n t a i n i n g a t e m p e r a t u r e o f 95'C and equipped w i t h 250-mL c o n s t r i c t e d d i g e s t i o n tubes.

p l a t e capable o f maintaining a


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6.5

(optional) A steel cabinet centrifuge with guard bowl, electric timer and brake.

6.6

A gravity convection drying oven with thermostatic control capable of maintaining 18OoC k 5°C.

6.7

(optional) An air displacement pipetter capable o f delivering volumes ranging from 100 to 2500 pL with an assortment of high quality disposable pipet tips.

6.8

Mortar and pestle, ceramic or nonmetallic material.

6.9

Polypropylene sieve, 5-mesh ( 4 mm opening).

6.10 Labware - All reusable labware (glass, quartz, polyethylene, PTFE, FEP, etc.) should be sufficiently clean for the task objectives. Several procedures found to provide clean 1 abware include washing with a detergent solution, rinsing with tap water, soaking for 4 h or more in 20% (v/v) nitric acid or a mixture of diluterN0, and HC1 ( 1 + 2 + 9 ) , rinsing with reagent water and storing clean. Ideally, ground glass surfaces should be avoided to eliminate a potential source of random contamination. When this is impractical, particular attention should be given to all ground glass surfaces during cleaning. Chromic acid cleaning solutions must be avoided because chromium is an analyte.

7.0

6.10.1

Glassware - Volumetric flasks, graduated cylinders, funnels and centrifuge tubes (glass and /or metal-free plastic).

6.10.2

Assorted calibrated pipettes.

6.10.3

Conical Phillips beakers, 250-mL with 50-mm watch gl asses.

6.10.4

Griffin beakers, 250-mL with 75-mm watch glasses and (optional) 75-mm ribbed watch glasses.

6.10.5

(optional) PTFE and/or quartz Griffin beakers, 250-mL with PTFE covers.

6. 0.6

Evaporating dishes or high-form crucibles, porcelain, 100 mL capacity.

6. 0.7

Narrow-mouth storage bottles, FEP (fluorinated ethylene propylene) with screw closure, 125-mL to l-L capacities.

6. 0.8

One-piece stem FEP wash bottle with screw closure, 125mL capacity.

REAGENTS AND STANDARDS

7.1

Reagents may contain elemental impurities which might affect analytical data. Only high-purity reagents that conform to the Revision 2.2 May 1994

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American Chemical S o c i e t y s p e c i f i c a t i o n s ' s h o u l d be used whenever possible. I f the p u r i t y o f a reagent i s i n question, analyze f o r c o n t a m i n a t i o n . A l l a c i d s used f o r t h i s method must be o f u l t r a h i g h - p u r i t y grade o r e q u i v a l e n t . S u i t a b l e a c i d s a r e a v a i l a b l e f r o m a number o f m a n u f a c t u r e r s . R e d i s t i l l e d a c i d s p r e p a r e d by subb o i l i n g d i s t i l l a t i o n are acceptable.

7.2

H y d r o c h l o r i c a c i d , c o n c e n t r a t e d ( s p . g r . 1.19) - HC1.

7.2.1 H y d r o c h l o r i c a c i d (ltl) - Add 500 mL c o n c e n t r a t e d HC1 t o 400 mL r e a g e n t w a t e r and d i l u t e t o 1 L. 7.2.2 H y d r o c h l o r i c a c i d (1t4) - Add 200 mL c o n c e n t r a t e d HC1 t o 400 mL r e a g e n t w a t e r and d i l u t e t o 1 L. 7.3

N i t r i c acid, concentrated (sp.gr.

1.41)

- HNO,.

- Add 500 mL c o n c e n t r a t e d HNO, r e a g e n t w a t e r and d i l u t e t o 1 L.

7.3.1 N i t r i c a c i d (ltl)

7.3.2 N i t r i c a c i d (1t5)

t o 400 mL

- Add

50 mL c o n c e n t r a t e d HNO, t o 250 mL

- Add

10 mL c o n c e n t r a t e d HNO, t o 90 mL

reagent water.

7.3.3 N i t r i c a c i d (1t9) reagent water.

7.4

Reagent w a t e r . A l l preferences t o w a t e r i n t h i s method r e f e r t o ASTM Type I grade w a t e r .

7.5

Ammonium h y d r o x i d e , c o n c e n t r a t e d ( s p . g r . 0.902).

7.6

T a r t a r i c a c i d , ACS r e a g e n t grade.

7.7

M a t r i x M o d i f i e r , d i s s o l v e 300 mg p a l l a d i u m (Pd) powder i n conc. HNO, adding 0.1 mL o f c o n c e n t r a t e d HC1 i f necessary). (1 mL o f HNO,, Pour t h e two D i s s o l v e 200 mg o f Mg(N0 ) i n ASTM Type I w a t e r . s o l u t i o n s t o g e t h e r and d i j u i e t o 100 mL w i t h ASTM Type I w a t e r .

NOTE: I t i s recommended t h a t t h e m a t r i x m o d i f i e r be analyzed s e p a r a t e l y i n o r d e r t o assess t h e c o n t r i b u t i o n o f t h e m o d i f i e r t o t h e absorbance o f c a l i b r a t i o n and r e a g e n t b l a n k s o l u t i o n s . 7.8

Standard s t o c k s o l u t i o n s may be purchased o r p r e p a r e d f r o m u l t r a h i g h p u r i t y grade c h e m i c a l s (99.99 t o 99.999% p u r e ) . A l l compounds must be d r i e d f o r 1 h a t 1 0 5 O C , u n l e s s o t h e r w i s e s p e c i f i e d . I t i s recommended t h a t s t o c k s o l u t i o n s be s t o r e d i n FEP b o t t l e s . Replace s t o c k standards when succeeding d i l u t i o n s f o r p r e p a r a t i o n o f c a l i b r a t i o n standards can n o t be v e r i f i e d . CAUTION:

Many o f t h e s e c h e m i c a l s a r e e x t r e m e l y t o x i c i f i n h a l e d o r swallowed ( S e c t . 5 . 1 ) . Wash hands t h o r o u g h l y a f t e r hand1 ing .


158

Methods for the Determination T y p i c a l s t o c k s o l u t i o n p r e p a r a t i o n procedures f o l l o w f o r l - L q u a n t i t i e s , b u t f o r t h e purpose o f p o l l u t i o n p r e v e n t i o n , t h e a n a l y s t i s encouraged t o p r e p a r e s m a l l e r q u a n t i t i e s when p o s s i b l e . C o n c e n t r a t i o n s a r e c a l c u l a t e d based upon t h e w e i g h t o f t h e p u r e element o r upon t h e w e i g h t o f t h e compound m u l t i p l i e d by t h e f r a c t i o n o f t h e a n a l y t e i n t h e compound. From pure element, w e i g h t (mg) Concentration

=

volume ( L ) From pure compound, w e i g h t (mg) x g r a v i m e t r i c f a c t o r Concentration = volume ( L ) where : gravimetric factor

=

t h e weight f r a c t i o n o f t h e analyte i n t h e compound.

7.8.1

Aluminum s o l u t i o n , s t o c k , 1 mL = 1000 p g A l : D i s s o l v e 1.000 g o f aluminum m e t a l , weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n an a c i d m i x t u r e o f 4.0 mL o f ( l t l ) HC1 and 1 . 0 mL o f c o n c e n t r a t e d HNO, i n a beaker. Warm beaker slowly t o e f f e c t solution. When d i s s o l u t i o n i s complete, t r a n s f e r s o l u t i o n q u a n t i t a t i v e l y t o a 1-L f l a s k , add an a d d i t i o n a l 10.0 mL o f ( l t l ) HC1 and d i l u t e t o volume w i t h reagent water.

7.8.2

Antimony s o l u t i o n , s t o c k , 1 m L = 1000 pg Sb: D i s s o l v e 1.000 g o f antimony powder, weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 20.0 mL ( l t l ) HNO, and 10.0 mL c o n c e n t r a t e d HC1. Add 100 mL r e a g e n t w a t e r and 1.50 g t a r t a r i c acid. Warm s o l u t i o n s l i g h t l y t o e f f e c t complete d i s s o l u t i o n . Cool s o l u t i o n and add r e a g e n t w a t e r t o volume i n a l-L volumetric flask.

7.8.3

A r s e n i c s o l u t i o n , s t o c k , 1 mL = 1000 p g As: D i s s o l v e 1.320 g o f As,O (As f r a c t i o n = 0.7574), weighed a c c u r a t e l y t o a t l e a s t t o u r s i g n i f i c a n t f i g u r e s , i n 100 mL o f r e a g e n t w a t e r c o n t a i n i n g 10.0 mL c o n c e n t r a t e d NH,OH. Warm t h e s o l u t i o n g e n t l y t o e f f e c t d i s s o l u t i o n . A c i d i f y t h e s o l u t i o n w i t h 20.0 mL c o n c e n t r a t e d HNO, and d i l u t e t o volume i n a l - L v o l u m e t r i c f l a s k w i t h reagent water.

7.8.4

B e r y l l i u m s o l u t i o n , s t o c k , 1 mL = 1000 p g Be: DO NOT DRY. D i s s o l v e 19.66 g BeS0,*4H20 (Be f r a c t i o n = 0.0509), weighed accurately t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n reagent Revision 2.2 Hay 1994

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w a t e r , add 1 0 . 0 mL c o n c e n t r a t e d HNO,, and d i l u t e t o volume i n a 1-L v o l u m e t r i c f l a s k w i t h r e a g e n t w a t e r .

7.8.5

Cadmium s o l u t i o n , s t o c k , 1 mL = 1000 p g Cd: D i s s o l v e 1.000 g Cd m e t a l , a c i d cleaned w i t h ( 1 t 9 ) HNO,, weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 50 mL ( l t l ) HNO w i t h h e a t i n g t o e f f e c t d i s s o l u t i o n . L e t s o l u t i o n c o o l and d i l u t e w i t h r e a g e n t w a t e r i n a l-L v o l u m e t r i c f l a s k .

7.8.6

Chromium s o l u t i o n , s t o c k , 1 mL = 1000 pg C r : D i s s o l v e 1.923 g CrO, ( C r f r a c t i o n = 0.5200), weighed a c c u r a t e l y t o a t l e a s t When s o l u t i o n f o u r s i g n i f i c a n t f i g u r e s , i n 120 mL (1+5) HNO,. i s complete, d i l u t e t o volume i n a l - L v o l u m e t r i c f l a s k w i t h reagent water.

7.8.7

C o b a l t s o l u t i o n , s t o c k , 1 mL = 1000 p g Co: D i s s o l v e 1 , 0 0 0 g Co m e t a l , a c i d c l e a n e d w i t h ( 1 t 9 ) HNO,, weighed a c c u r a t e l y t o Let a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 50.0 mL (1+1) HNO,. s o l u t i o n c o o l and d i l u t e t o volume i n a l-L v o l u m e t r i c f l a s k w i t h reagent water.

7.8.8

Copper s o l u t i o n , s t o c k , 1 mL = 1000 p g Cu: D i s s o l v e 1.000 g Cu m e t a l , a c i d c l e a n e d w i t h ( 1 t 9 ) HNO,, weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 50.0 mL (1+1) HNO, w i t h h e a t i n g t o e f f e c t d i s s o l u t i o n . L e t s o l u t i o n c o o l and d i l u t e i n a l - L v o l u m e t r i i f l a s k w i t h reagent water.

7.8.9

I r o n s o l u t i o n , s t o c k , 1 mL = 1000 pg Fe: D i s s o l v e 1.000 g Fe m e t a l , a c i d c l e a n e d w i t h ( l t l ) HC1, weighed a c c u r a t e l y t o f o u r s i g n i f i c a n t f i g u r e s , i n 100 mL ( l t l ) HC1 w i t h h e a t i n g t o e f f e c t d i s s o l u t i o n . L e t s o l u t i o n c o o l and d i l u t e w i t h r e a g e n t water i n a l - L volumetric f l a s k .

7.8.10

Lead s o l u t i o n , s t o c k , 1 mL = 1000 b g Pb: D i s s o l v e 1.599 g Pb(N0,) (Pb f r a c t i o n = 0 . 6 2 5 6 ) , weighed a c c u r a t e l y t o a t l e a s t t o u r s i g n i f i c a n t f i g u r e s , i n a minimum amount o f ( 1 t 1 ) Add 20.0 mL ( l t l ) HNO, and d i l u t e t o volume i n a l - L HNO,. volumetric f l a s k w i t h reagent water.

7.8.11

Manganese s o l u t i o n , s t o c k , 1 mL = 1000 pg Mn: D i s s o l v e 1.000 g o f manganese m e t a l , weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 50 mL ( l t l ) HNO, and d i l u t e t o volume i n a l-L v o l u m e t r i c f l a s k w i t h r e a g e n t w a t e r .

7.8.12

N i c k e l s o l u t i o n , s t o c k , 1 mL = 1000 1-19 N i : D i s s o l v e 1.000 g o f n i c k e l m e t a l , weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 20.0 mL h o t c o n c e n t r a t e d HNO, c o o l , and d i l u t e t o volume i n a l - L v o l u m e t r i c f l a s k w i t h reagent water.

7.8.13

Selenium s o l u t i o n , s t o c k , 1 mL = 1000 pg Se: D i s s o l v e 1.405 g SeO,,(Se f r a c t i o n = 0 . 7 1 1 6 ) , weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 200 mL r e a g e n t w a t e r and d i l u t e t o volume i n a l - L v o l u m e t r i c f l a s k w i t h r e a g e n t w a t e r . Revision 2.2 Nay 1994

160


7.8.14 S i l v e r s o l u t i o n , s t o c k , 1 mL

= 1000 pg Ag: D i s s o l v e 1.000 g Ag m e t a l , weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n 80 mL ( l t l ) HNO, w i t h h e a t i n g t o e f f e c t d i s s o l u t i o n . L e t s o l u t i o n c o o l and d i l u t e w i t h r e a g e n t w a t e r i n a l - L v o l u m e t r i c f l a s k . S t o r e s o l u t i o n i n amber b o t t l e o r wrap b o t t l e c o m p l e t e l y w i t h aluminum f o i l t o p r o t e c t s o l u t i o n from l i g h t .

7.8.15 T h a l l i u m s o l u t i o n , s t o c k , 1 mL = 1000 p g T1: D i s s o l v e 1.303 g TlNO, (T1 f r a c t i o n = 0.7672), weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n reagent water. Add 10.0 mL c o n c e n t r a t e d HNO, and d i l u t e t o volume i n a l - L v o l u m e t r i c f l a s k w i t h reagent water.

7.8.16 T i n s o l u t i o n , s t o c k , 1 mL

= 1000 p g Sn: D i s s o l v e 1.000 g Sn s h o t , weighed a c c u r a t e l y t o a t l e a s t f o u r s i g n i f i c a n t f i g u r e s , i n an a c i d m i x t u r e o f 10.0 mL c o n c e n t r a t e d HC1 and 2.0 mL (ltl) HNO, w i t h h e a t i n g t o e f f e c t d i s s o l u t i o n . L e t s o l u t i o n c o o l , add 200 mL c o n c e n t r a t e d HC1, and d i l u t e t o volume i n a l-L v o l u m e t r i c f l a s k w i t h r e a g e n t w a t e r .

7.9

P r e p a r a t i o n o f C a l i b r a t i o n Standards - Fresh c a l i b r a t i o n standards (CAL S o l u t i o n ) s h o u l d be p r e p a r e d e v e r y two weeks, o r as needed. D i l u t e each ofi t h e s t o c k s t a n d a r d s o l u t i o n s t o l e v e l s a p p r o p r i a t e t o t h e o p e r a t i n g range o f t h e i n s t r u m e n t u s i n g t h e a p p r o p r i a t e a c i d d i l u e n t (see n o t e ) . The element c o n c e n t r a t i o n s i n each CAL s o l u t i o n s h o u l d be s u f f i c i e n t l y h i g h t o produce good measurement p r e c i s i o n and t o a c c u r a t e l y d e f i n e t h e s l o p e o f t h e response c u r v e . The i n s t r u m e n t c a l i b r a t i o n s h o u l d be i n i t i a l l y v e r i f i e d u s i n g a q u a l i t y c o n t r o l sample ( S e c t i o n s 7.12 & 9.2.3).

NOTE:

The a p p r o p r i a t e a c i d d i l u e n t f o r t h e d e t e r m i n a t i o n o f d i s s o l v e d elements i n w a t e r and f o r t h e " d i r e c t a n a l y s i s " o f d r i n k i n g w a t e r w i t h t u r b i d i t y < 1 NTU i s 1% HNO,. For t o t a l r e c o v e r a b l e elements i n w a t e r s , t h e a p p r o p r i a t e a c i d d i l u e n t i s 2% HNO, and 1% HC1, and t h e a p p r o p r i a t e a c i d d i l u e n t f o r t o t a l r e c o v e r a b l e elements i n s o l i d samples i s 2% HNO, and 2% HC1. The reason f o r t h e s e d i f f e r e n t d i l u e n t s i s t o match t h e t y p e s o f a c i d s and t h e a c i d c o n c e n t r a t i o n s o f t h e samples w i t h t h e a c i d p r e s e n t i n t h e standards and b l a n k s .

7.10 Blanks - Four t y p e s o f b l a n k s a r e r e q u i r e d f o r t h i s method.

A c a l i b r a t i o n b l a n k i s used t o e s t a b l i s h t h e a n a l y t i c a l c a l i b r a t i o n curve, t h e l a b o r a t o r y r e a g e n t b l a n k (LRB) i s used t o assess p o s s i b l e c o n t a m i n a t i o n f r o m t h e sample p r e p a r a t i o n procedure and t o assess s p e c t r a l background, t h e l a b o r a t o r y f o r t i f i e d b l a n k i s used t o assess r o u t i n e l a b o r a t o r y performance, and a r i n s e b l a n k i s used t o f l u s h t h e i n s t r u m e n t autosampler uptake system. A l l d i l u e n t a c i d s s h o u l d be made f r o m c o n c e n t r a t e d a c i d s ( S e c t s . 7.2 & 7.3) and ASTM Type I w a t e r .

7.10.1 The c a l i b r a t i o n b l a n k c o n s i s t s o f t h e a p p r o p r i a t e a c i d d i l u e n t i n ASTM Type I w a t e r . The ( S e c t . 7.9 n o t e ) (HCl/HNO,) c a l i b r a t i o n b l a n k should be s t o r e d i n a FEP b o t t l e . Revision 2.2 Nay 1994

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7.10.2

The l a b o r a t o r y r e a g e n t b l a n k (LRB) must c o n t a i n a l l t h e r e a g e n t s i n t h e same volumes as used i n p r o c e s s i n g t h e samples. The LRB must be c a r r i e d t h r o u g h t h e same e n t i r e p r e p a r a t i o n scheme as t h e samples i n c l u d i n g sample d i g e s t i o n , when appl icab1 e .

7.10.3

The 1 a b o r a t o r y f o r t if ied b l ank (LFB) is p r e p a r e d by f o r t if y i n g an a l i q u o t o f t h e l a b o r a t o r y r e a g e n t b l a n k w i t h a l l a n a l y t e s t o p r o v i d e a f i n a l c o n c e n t r a t i o n which w i l l produce an absorbance o f a p p r o x i m a t e l y 0 . 1 f o r each a n a l y t e . The LFB must be c a r r i e d t h r o u g h t h e same e n t i r e p r e p a r a t i o n scheme as t h e samples i n c l u d i n g sample d i g e s t i o n , when a p p l i c a b l e .

7.10.4

The r i n s e b l a n k i s p r e p a r e d as needed by adding 1.0 mL o f conc. HNO, and 1 . 0 mL conc. HC1 t o 1 l i t e r o f ASTM Type I w a t e r and s t o r e d i n a c o n v e n i e n t manner.

7.11 I n s t r u m e n t Performance Check (IPC) S o l u t i o n - The I P C s o l u t i o n i s used t o p e r i o d i c a l l y v e r i f y i n s t r u m e n t performance d u r i n g a n a l y s i s . It s h o u l d be p r e p a r e d i n t h e same a c i d m i x t u r e as t h e c a l i b r a t i o n standards ( S e c t , 7.9 n o t e ) by combining method a n a l y t e s a t a p p r o p r i a t e c o n c e n t r a t i o n s t o approximate t h e m i d p o i n t o f t h e c a l i b r a t i o n c u r v e . The I P C s o l u t i o n s h o u l d be p r e p a r e d f r o m t h e same standard s t o c k s o l u t i o n s used t o p r e p a r e t h e c a l i b r a t i o n standards and s t o r e d i n a FEP b o t t l e . Agency programs may s p e c i f y o r r e q u e s t t h a t a d d i t i o n a l i n s t r u m e n t performance check s o l u t i o n s be prepared a t s p e c i f i e d c o n c e n t r a t i o n s i n o r d e r t o meet p a r t i c u l a r program needs. 7.12 Q u a l i t y C o n t r o l Sample (QCS) - F o r i n i t i a l and p e r i o d i c v e r i f i c a t i o n o f c a l i b r a t i o n s t a n d a r d s and i n s t r u m e n t performance, a n a l y s i s o f a QCS i s required. The QCS must be o b t a i n e d f r o m an o u t s i d e source d i f f e r e n t f r o m t h e s t a n d a r d s t o c k s o l u t i o n s and prepared i n t h e same a c i d m i x t u r e as t h e c a l i b r a t i o n s t a n d a r d s ( S e c t . 7 . 9 n o t e ) . The c o n c e n t r a t i o n o f t h e a n a l y t e s i n t h e QCS s o l u t i o n s h o u l d be such t h a t t h e r e s u l t i n g s o l u t i o n w i l l p r o v i d e an absorbance r e a d i n g o f a p p r o x i m a t e l y 0.1. The QCS s o l u t i o n s h o u l d be s t o r e d i n a FEP b o t t l e and a n a l y z e d as needed t o meet d a t a - q u a l i t y needs. A f r e s h s o l u t i o n s h o u l d be p r e p a r e d q u a r t e r l y o r more f r e q u e n t l y as needed. 8.0

SAMPLE COLLECTION, PRESERVATION, AND STORAGE 8.1

P r i o r t o t h e c o l l e c t i o n o f an aqueous sample, c o n s i d e r a t i o n s h o u l d be given t o t h e type o f data required, ( i . e . , dissolved o r t o t a l r e c o v e r a b l e ) , so t h a t a p p r o p r i a t e p r e s e r v a t i o n and p r e t r e a t m e n t steps can be t a k e n . The pH o f a l l aqueous samples must be t e s t e d i m m e d i a t e l y p r i o r t o a1 i q u o t i n g f o r p r o c e s s i n g o r " d i r e c t a n a l y s i s " t o ensure t h e sample has been p r o p e r l y p r e s e r v e d . I f properly acid preserved, t h e sample can be h e l d up t o 6 months b e f o r e a n a l y s i s .

8.2

F o r t h e d e t e r m i n a t i o n o f t h e d i s s o l v e d elements, t h e sample must be f i l t e r e d t h r o u g h a 0.45-pm p o r e d i a m e t e r membrane f i l t e r a t t h e t i m e o f c o l l e c t i o n o r as soon t h e r e a f t e r as p r a c t i c a l l y p o s s i b l e . (Glass o r p l a s t i c f i l t e r i n g apparatus a r e recommended t o a v o i d p o s s i b l e contamination.) Use a p o r t i o n o f t h e f i l t e r e d sample t o r i n s e t h e Revision 2.2 May 1994

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Methods for the Determination f i l t e r f l a s k , d i s c a r d t h i s p o r t i o n and c o l l e c t t h e r e q u i r e d volume o f filtrate. A c i d i f y the f i l t r a t e w i t h ( l t l ) n i t r i c a c i d immediately f o l l o w i n g f i l t r a t i o n t o pH < 2.

8.3

For t h e d e t e r m i n a t i o n o f t o t a l r e c o v e r a b l e elements i n aqueous samples, samples a r e n o t f i l t e r e d , b u t a c i d i f i e d w i t h ( l t l ) n i t r i c a c i d t o pH < 2 ( n o r m a l l y , 3 mL o f (1t1) a c i d p e r l i t e r o f sample i s s u f f i c i e n t f o r most ambient and d r i n k i n g w a t e r samples). P r e s e r v a t i o n may be done a t t h e t i m e o f c o l l e c t i o n , however, t o a v o i d t h e hazards o f s t r o n g a c i d s i n t h e f i e l d , t r a n s p o r t r e s t r i c t i o n s , and p o s s i b l e c o n t a m i n a t i o n i t i s recommended t h a t t h e samples be r e t u r n e d t o t h e l a b o r a t o r y w i t h i n two weeks o f c o l l e c t i o n and a c i d p r e s e r v e d upon r e c e i p t i n t h e l a b o r a t o r y . F o l l o w i n g a c i d i f i c a t i o n , t h e sample s h o u l d be mixed, h e l d f o r s i x t e e n hours, and t h e n v e r i f i e d t o be pH < 2 j u s t p r i o r w i t h d r a w i n g an a l i q u o t f o r p r o c e s s i n g o r " d i r e c t a n a l y s i s " . If f o r some reason such as h i g h a l k a l i n i t y t h e sample pH i s v e r i f i e d t o be > 2 , more a c i d must be added and t h e sample h e l d f o r s i x t e e n h o u r s u n t i l v e r i f i e d t o be pH < 2 . See S e c t i o n 8.1.

NOTE:

When t h e n a t u r e o f t h e sample i s e i t h e r unknown o r i s known t o be hazardous, a c i d i f i c a t i o n s h o u l d be done i n a fume hood. See S e c t i o n 5.2.

8.4

S o l i d samples u s u a l l y r e q u i r e no p r e s e r v a t i o n p r i o r t o a n a l y s i s o t h e r t h a n s t o r a g e a t 4°C. There i s no e s t a b l i s h e d h o l d i n g t i m e l i m i t a t i o n f o r s o l i d samples.

8.5

F o r aqueous samples, a f i e l d b l a n k s h o u l d be p r e p a r e d and a n a l y z e d as r e q u i r e d by t h e d a t a u s e r . Use t h e same c o n t a i n e r and a c i d as used i n sampl e c o l 1e c t i on.

9.0 QUALITY CONTROL 9.1

Each l a b o r a t o r y u s i n g t h i s method i s r e q u i r e d t o o p e r a t e a f o r m a l q u a l i t y c o n t r o l (QC) program. The minimum r e q u i r e m e n t s o f t h i s program c o n s i s t of an i n i t i a l d e m o n s t r a t i o n o f l a b o r a t o r y c a p a b i l i t y , and t h e p e r i o d i c a n a l y s i s o f l a b o r a t o r y r e a g e n t b l a n k s , f o r t i f i e d b l a n k s and o t h e r l a b o r a t o r y s o l u t i o n s as a c o n t i n u i n g check on performance. The l a b o r a t o r y i s r e q u i r e d t o m a i n t a i n performance r e c o r d s t h a t d e f i n e t h e q u a l i t y o f t h e d a t a t h u s generated.

9.2

I n i t i a l Demonstration o f Performance (mandatory)

9.2.1

The i n i t i a l d e m o n s t r a t i o n o f performance i s used t o c h a r a c t e r i z e i n s t r u m e n t performance ( d e t e r m i n a t i o n o f 1 i n e a r dynamic ranges and a n a l y s i s o f q u a l i t y c o n t r o l samples) and l a b o r a t o r y performance ( d e t e r m i n a t i o n o f method d e t e c t i o n l i m i t s ) p r i o r t o samples b e i n g analyzed by t h i s method.

9.2.2

L i n e a r dynamic range (LDR) - The upper l i m i t o f t h e LDR must be e s t a b l i s h e d f o r t h e wavelength u t i l i z e d f o r each a n a l y t e by d e t e r m i n i n g t h e s i g n a l responses from a minimum o f s i x d i f f e r e n t c o n c e n t r a t i o n standards across t h e range, two o f Revision 2.2 Nay 1994

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w h i c h a r e c l o s e t o t h e upper l i m i t o f t h e LDR. Determined LDRs must be documented and k e p t on f i l e . The l i n e a r c a l i b r a t i o n range which may be used f o r t h e a n a l y s i s o f samples s h o u l d be judged by t h e a n a l y s t from t h e r e s u l t i n g d a t a . The upper LDR l i m i t s h o u l d be an observed s i g n a l no more t h a n 10% below t h e l e v e l e x t r a p o l a t e d from t h e f o u r l o w e r standards. The LDRs s h o u l d be v e r i f i e d whenever, i n t h e judgement o f t h e a n a l y s t , a change i n a n a l y t i c a l performance caused by e i t h e r a change i n i n s t r u m e n t hardware o r o p e r a t i n g c o n d i t i o n s would d i c t a t e t h e y be r e d e t e r m i n e d .

NOTE:

M u l t i p l e c l e a n o u t f u r n a c e c y c l e s may be necessary i n o r d e r t o f u l l y d e f i n e o r u t i l i z e t h e LDR f o r c e r t a i n elements such as chromium. F o r t h i s reason t h e upper l i m i t o f t h e l i n e a r c a l i b r a t i o n range may n o t c o r r e s p o n d t o t h e upper LDR l i m i t .

Determined sample a n a l y t e c o n c e n t r a t i o n s t h a t exceed t h e upper l i m i t o f t h e l i n e a r c a l i b r a t i o n range must e i t h e r be d i l u t e d and r e a n a l y z e d w i t h concern f o r memory e f f e c t s ( S e c t . 4 . 4 ) o r a n a l y z e d by a n o t h e r approved method.

9.2.3

Q u a l i t y c o n t r o l sample (QCS) - When b e g i n n i n g t h e use o f t h i s method, on a q u a r t e r l y b a s i s o r as r e q u i r e d t o meet dataqua1 i t y needs, v e r i f y t h e c a l i b r a t i o n standards and a c c e p t a b l e i n s t r u m e n t performance w i t h t h e p r e p a r a t i o n and analyses o f a QCS ( S e c t . 7 . 1 2 ) . I f t h e determined concentrations are n o t w i t h i n _+ 10% o f t h e s t a t e d v a l u e s , performance o f t h e d e t e r m i n a t i v e s t e p o f t h e method i s u n a c c e p t a b l e . The source o f t h e problem must be i d e n t i f i e d and c o r r e c t e d b e f o r e e i t h e r p r o c e e d i n g on w i t h t h e i n i t i a l d e t e r m i n a t i o n o f method d e t e c t i o n l i m i t s o r c o n t i n u i n g w i t h on-going analyses.

9.2.4

Method d e t e c t i o n l i m i t (MDL) - MDLs must be e s t a b l i s h e d f o r a l l analytes, using reagent water (blank) f o r t i f i e d a t a concentration o f t o t h r e e times t h e estimated instrument detection l i m i t . To d e t e r m i n e MDL values, t a k e seven r e p l i c a t e a1 i q u o t s o f t h e f o r t i f i e d r e a g e n t w a t e r and process t h r o u g h t h e e n t i r e a n a l y t i c a l method. P e r f o r m a l l c a l c u l a t i o n s d e f i n e d i n t h e method and r e p o r t t h e c o n c e n t r a t i o n v a l u e s i n t h e a p p r o p r i a t e u n i t s . C a l c u l a t e t h e MDL as f o l l o w s :

20

MDL

=

( t ) x (S)

where: t

=

s t u d e n t s ’ t v a l u e f o r a 99% c o n f i d e n c e l e v e l and a s t a n d a r d d e v i a t i o n e s t i m a t e w i t h n-1 degrees o f freedom [ t = 3.14 f o r seven r e p l i c a t e s ] .

S

=

s t a n d a r d d e v i a t i o n o f t h e r e p l i c a t e analyses.

Note:

I f a d d i t i o n a l c o n f i r m a t i o n i s desired, reanalyze the seven r e p l ic a t e a1 iquot s on two more nonconsecutive days and a g a i n c a l c u l a t e t h e MDL v a l u e s f o r each day. Revision 2.2 Hay 1994

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Methods for the Determination An average o f t h e t h r e e MDL v a l u e s f o r each a n a l y t e may p r o v i d e f o r a more a p p r o p r i a t e MDL e s t i m a t e . If t h e r e l a t i v e s t a n d a r d d e v i a t i o n (RSD) from t h e analyses o f t h e seven a l i q u o t s i s < lo%, t h e c o n c e n t r a t i o n used t o d e t e r m i n e t h e a n a l y t e MDL may have been inappropr i a t e l y h i g h f o r t h e d e t e r m i n a t i o n . I f so, t h i s c o u l d r e s u l t i n t h e c a l c u l a t i o n o f an u n r e a l i s t i c a l l y l o w MDL. C o n c u r r e n t l y , d e t e r m i n a t i o n o f MDL i n r e a g e n t w a t e r r e p r e s e n t s a b e s t case s i t u a t i o n and does n o t r e f l e c t p o s s i b l e m a t r i x e f f e c t s o f r e a l w o r l d samples. However, s u c c e s s f u l analyses o f LFMs ( S e c t . 9.4) and t h e a n a l y t e a d d i t i o n t e s t d e s c r i b e d i n S e c t i o n 9.5.1 can g i v e c o n f i d e n c e t o t h e MDL v a l u e d e t e r m i n e d i n r e a g e n t w a t e r . T y p i c a l s i n g l e l a b o r a t o r y MDL v a l u e s u s i n g t h i s method a r e g i v e n i n Table 2. The MDLs must be s u f f i c i e n t t o d e t e c t a n a l y t e s a t t h e r e q u i r e d l e v e l s a c c o r d i n g t o compliance m o n i t o r i n g r e g u l a t i o n ( S e c t . 1.2). MDLs s h o u l d be determined a n n u a l l y , when a new o p e r a t o r b e g i n s work o r whenever, i n t h e judgement o f t h e a n a l y s t , a change i n a n a l y t i c a l performance caused by e i t h e r a change i n i n s t r u m e n t hardware o r o p e r a t i n g c o n d i t i o n s would d i c t a t e t h e y be r e d e t e r m i n e d .

9.3 Assessing L a b o r a t o r y Performance (mandatory) 9.3.1

L a b o r a t o r y r e a g e n t b l a n k (LRB) - The l a b o r a t o r y must a n a l y z e a t l e a s t one LRB ( S e c t . 7.10.2) w i t h each b a t c h o f 20 o r fewer samples o f t h e same m a t r i x . LRB d a t a a r e used t o assess c o n t a m i n a t i o n f r o m t h e l a b o r a t o r y environment. LRB v a l u e s t h a t exceed t h e MDL i n d i c a t e l a b o r a t o r y o r r e a g e n t c o n t a m i n a t i o n s h o u l d be suspected. When LRB v a l u e s c o n s t i t u t e 10% o r more o f t h e a n a l y t e l e v e l d e t e r m i n e d f o r a sample o r i s 2.2 t i m e s t h e a n a l y t e MDL whichever i s g r e a t e r , f r e s h a l i q u o t s o f t h e samples must be p r e p a r e d and analyzed a g a i n f o r t h e a f f e c t e d a n a l y t e s a f t e r t h e source o f c o n t a m i n a t i o n has been c o r r e c t e d and a c c e p t a b l e LRB v a l u e s have been o b t a i n e d .

9.3.2 L a b o r a t o r y f o r t i f i e d b l a n k (LFB)

- The l a b o r a t o r y must a n a l y z e a t l e a s t one LFB ( S e c t . 7.10.3) w i t h each b a t c h o f samples. C a l c u l a t e accuracy as p e r c e n t r e c o v e r y u s i n g t h e f o l l o w i n g equation:

LFB - LRB

R =

x

100

S

where:

R LFB LRB s

= = = =

percent recovery. laboratory f o r t i f i e d blank. l a b o r a t o r y reagent blank. concentration equivalent o f analyte added t o f o r t i f y t h e LRB s o l u t i o n .


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If the recovery of any analyte falls outside the required control limits of 85-115%, that analyte is judged out of control, and the source of the problem should be identified and resolved before continuing analyses. 9.3.3

The laboratory must use LFB analyses data to assess laboratory performance against the required control limits of 85-115% (Sect.9.3.2). When sufficient internal performance data become available (usually a minimum of twenty to thirty analyses), optional control limits can be developed from the mean percent recovery ( x ) and the standard deviation ( S ) of the mean percent recovery. These data can be used to establish the upper and lower control limits as follows: UPPER CONTROL LIMIT LOWER CONTROL LIMIT

= =

x t 3s

x

-

3s

The optional control limits must be equal to or better than the required control limits of 85-115%. After each five to ten new recovery measurements, new control 1 imits can be calculated using only the most recent twenty to thirty data points. Also, the standard deviation ( S ) data should be used to established an on-going precision statement for the level of concentrations included in the LFB. These data must be kept on file and be available for review. 9.3.4

9.4

Instrument performance check (IPC) solution - For all determinations the laboratory must analyze the IPC solution (Sect. 7.11) and a calibration blank immediately following each calibration, after every tenth sample (or more frequently, if required) and at the end of the sample run. Analysis of the calibration blank should always be < the IDL, but > a negative signal in concentration units equal to the IDL. Analysis of the IPC solution immediately following calibration must verify that the instrument is within f 5% of calibration. Subsequent analyses of the IPC solution must be within f 10 % of calibration. If the calibration cannot be verified within the specified limits, reanalyze either or both the IPC solution and the calibration blank. If the second analysis of the IPC solution or the calibration blank confirm the calibration to be outside the limits, sample analysis must be discontinued, the cause determined and/or in the case of drift the instrument recalibrated. All samples following the last acceptable IPC solution must be reanalyzed. The analysis data of the calibration blank and IPC solution must be kept on file with the sample analyses data.

Assessing Analyte Recovery and Data Quality 9.4.1

Sample homogeneity and the chemical nature of the sample matrix can affect analyte recovery and the quality of the data. Taking separate aliquots from the sample for replicate and fortified analyses can in sotiie cases assess these effects. Unless otherwise specified by t h e data user, laboratory or Revision 2.2 May 1994

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program, t h e f o l l o w i n g l a b o r a t o r y f o r t i f i e d m a t r i x (LFM) procedure ( S e c t . 9 . 4 . 2 ) i s r e q u i r e d . Also, t h e analyte a d d i t i o n t e s t ( S e c t . 9.5.1) can i n d i c a t e i f m a t r i x and o t h e r i n t e r f e r e n c e e f f e c t s a r e o p e r a t i v e i n s e l e c t e d samples. However, a l l samples must demonstrate a background absorbance < 1 . 0 b e f o r e t h e t e s t r e s u l t s o b t a i n e d can be c o n s i d e r e d r e 1 ia b l e . 9.4.2

The l a b o r a t o r y must add a known amount o f each a n a l y t e t o a minimum o f 10% o f t h e r o u t i n e samples. I n each case t h e LFM a l i q u o t must be a d u p l i c a t e o f t h e a l i q u o t used f o r sample a n a l y s i s and f o r t o t a l r e c o v e r a b l e d e t e r m i n a t i o n s added p r i o r t o sample p r e p a r a t i o n . F o r w a t e r samples, t h e added a n a l y t e c o n c e n t r a t i o n must be t h e same as t h a t used i n t h e l a b o r a t o r y f o r t i f i e d b l a n k ( S e c t . 9.3.2). F o r s o l i d samples, however, t h e c o n c e n t r a t i o n added s h o u l d be expressed as mg/kg and i s c a l c u l a t e d f o r a 1 g a l i q u o t by m u l t i p l y i n g t h e added a n a l y t e c o n c e n t r a t i o n (pg/L) i n s o l u t i o n by t h e c o n v e r s i o n f a c t o r 0.1 (0.001 x pg/L x O.lL/O.OOlkg = 0.1, S e c t . 12.4). Over t i m e , samples from a l l r o u t i n e sample sources s h o u l d be f o r t i f i e d .

9.4.3

C a l c u l a t e t h e p e r c e n t r e c o v e r y f o r each a n a l y t e , c o r r e c t e d f o r c o n c e n t r a t i o n s measured i n t h e u n f o r t i f i e d sample, and compare these v a l u e s t o t h e d e s i g n a t e d LFM r e c o v e r y range o f 70-130%. Recovery c a l c u l a t i o n s a r e n o t r e q u i r e d i f t h e c o n c e n t r a t i o n added i s l e s s t h a n 25% o f t h e u n f o r t i f i e d sample c o n c e n t r a t i o n . Percent r e c o v e r y may be c a l c u l a t e d i n u n i t s a p p r o p r i a t e t o t h e m a t r i x , using t h e f o l l o w i n g equation:

c, R =

-

c x 100

~

S

where:

R C, C

s 9.4.4

percent recovery. f o r t i f i e d sample c o n c e n t r a t i o n . sample background c o n c e n t r a t i o n . = concentration equivalent o f analyte added t o f o r t i f y t h e sample. =

= =

I f t h e r e c o v e r y o f any a n a l y t e f a l l s o u t s i d e t h e d e s i g n a t e d LFM r e c o v e r y range ( b u t i s s t i l l w i t h i n t h e range o f c a l i b r a t i o n ) and t h e l a b o r a t o r y performance f o r t h a t a n a l y t e i s shown t o be i n c o n t r o l ( S e c t . 9.3), t h e r e c o v e r y problem encountered w i t h t h e LFM i s judged t o be e i t h e r m a t r i x o r s o l u t i o n r e l a t e d , n o t system r e l a t e d . I f t h e a n a l y t e r e c o v e r y i n t h e LFM i s < 70% and t h e background absorbance i s < 1.0, complete t h e a n a l y t e a d d i t i o n t e s t ( S e c t . 9.5.1) on an u n d i l u t e d p o r t i o n o f t h e u n f o r t i f i e d sample a l i q u o t . The t e s t r e s u l t s s h o u l d be e v a l u a t e d as f o l l o w s : 1. I f r e c o v e r y o f t h e a n a l y t e a d d i t i o n t e s t ( < 85%) c o n f i r m s t h e a l o w r e c o v e r y f o r t h e LFM, a s u p p r e s s i v e m a t r i x i n t e r f e r e n c e i s i n d i c a t e d and t h e u n f o r t i f i e d sample a1 i q u o t


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must be analyzed by method o f s t a n d a r d a d d i t i o n s (Sect.

11.5). 2. I f t h e r e c o v e r y o f t h e a n a l y t e a d d i t i o n t e s t i s between 85% t o 115%, a l o w r e c o v e r y o f t h e a n a l y t e i n t h e LFM ( < 70%) may be r e l a t e d t o t h e heterogeneous n a t u r e o f t h e sample, t h e r e s u l t o f p r e c i p i t a t i o n l o s s d u r i n g sample p r e p a r a t i o n , o r an i n c o r r e c t a d d i t i o n p r i o r t o p r e p a r a t i o n . Report a n a l y t e d a t a determined f r o m t h e a n a l y s i s o f t h e u n f o r t i f i e d sample a l i q u o t .

9.4.5

I f l a b o r a t o r y performance i s shown t o be i n c o n t r o l (Sect. 9 . 3 ) , b u t a n a l y t e r e c o v e r y i n t h e LFM i s e i t h e r > 130% or above t h e upper c a l i b r a t i o n l i m i t and t h e background absorbance i s < 1.0, complete t h e a n a l y t e a d d i t i o n t e s t ( S e c t . 9.5.1) on a p o r t i o n o f t h e u n f o r t i f i e d sample a l i q u o t . ( I f t h e determined LFM c o n c e n t r a t i o n i s above t h e upper c a l i b r a t i o n l i m i t , d i l u t e a portion o f the u n f o r t i f i e d aliquot accordingly with a c i d i f i e d reagent water before completing t h e analyte a d d i t i o n t e s t . ) E v a l u a t e t h e t e s t r e s u l t s as f o l l o w s : 1. If t h e p e r c e n t r e c o v e r y o f t h e a n a l y t e a d d i t i o n t e s t i s > 115%, an enhancing m a t r i x i n t e r f e r e n c e ( a l b e i t r a r e ) i s i n d i c a t e d and t h e u n f o r t i f i e d sample a l i q u o t o r i t s a p p r o p r i a t e d i l u t i o n must be analyzed by method o f standard a d d i t i o n s (Sect 11.5).

2. I f t h e p e r c e n t r e c o v e r y o f t h e a n a l y t e a d d i t i o n t e s t i s between 85% t o 115%, h i g h r e c o v e r y i n t h e LFM may have been caused by random sample c o n t a m i n a t i o n , an i n c o r r e c t a d d i t i o n o f t h e a n a l y t e p r i o r t o sample p r e p a r a t i o n , o r sample heterogeneity. Report a n a l y t e d a t a determined from t h e a n a l y s i s o f t h e u n f o r t i f i e d sample a l i q u o t o r i t s appropriate d i l u t i o n .

3. I f the percent recovery o f the analyte a d d i t i o n t e s t i s < 85%, e i t h e r a case o f b o t h random c o n t a m i n a t i o n and an o p e r a t i v e m a t r i x i n t e r f e r e n c e i n t h e LFM i s i n d i c a t e d o r a more p l a u s i b l e answer i s a heterogenous sample w i t h an s u p p r e s s i v e m a t r i x i n t e r f e r e n c e . Reported d a t a should be flagged accordingly. 9.4.6

I f l a b o r a t o r y performance i s shown t o be i n c o n t r o l ( S e c t . 9 . 3 ) , b u t t h e magnitude o f t h e sample (LFM o r u n f o r t i f i e d a l i q u o t ) background absorbance i s > 1 .O, a n o n - s p e c i f i c s p e c t r a l i n t e r f e r e n c e s h o u l d be suspected. A portion o f the u n f o r t i f i e d a l i q u o t s h o u l d be d i l u t e d ( 1 t 3 ) w i t h a c i d i f i e d r e a g e n t w a t e r and r e a n a l y z e d . ( D i l u t i o n may d r a m a t i c a l l y reduce a m o l e c u l a r background t o an a c c e p t a b l e l e v e l . I d e a l l y , t h e background absorbance i n t h e u n f o r t i f i e d a1 i q u o t d i l u t e d ( 1 t 3 ) s h o u l d be < 1 . 0 . However, a d d i t i o n a l d i l u t i o n may be necessary.) I f d i l u t i o n reduces t h e background absorbance t o a c c e p t a b l e l e v e l ( < l . O ) , complete t h e a n a l y t e a d d i t i o n t e s t ( S e c t . 9 . 5 . 1 ) on a p o r t i o n o f t h e d i l u t e d u n f o r t i f i e d a l i q u o t . Revision 2.2 Hay 1994

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Methods for the Determination E v a l u a t e t h e t e s t r e s u l t s as f o l l o w s 1. I f t h e r e c o v e r y o f t h e a n a l y t e a d d i t i o n t e s t i s between 85% t o 115%, r e p o r t a n a l y t e d a t a determined on t h e d i l u t i o n o f the u n f o r t i f i e d aliquot.

2. I f the recovery o f the analyte a d d i t i o n t e s t i s outside the range o f 85% t o 115%, complete t h e sample a n a l y s i s by a n a l y z i n g t h e d i l u t i o n o f t h e u n f o r t i f i e d a l i q u o t by method o f s t a n d a r d a d d i t i o n s (Sect. 11.5).

9.5

9.4.7

I f e i t h e r t h e a n a l y s i s o f a LFM sample(s) o r a p p l i c a t i o n o f t h e analyte addition t e s t routine i n d i c a t e an o p e r a t i v e i n t e r f e r e n c e , a l l o t h e r samples i n t h e b a t c h which a r e t y p i c a l and have s i m i l a r m a t r i x t o t h e LFMs o r t h e samples t e s t e d must be analyzed i n t h e same manner. A l s o , t h e d a t a u s e r must be i n f o r m e d when a m a t r i x i n t e r f e r e n c e i s so severe t h a t i t p r e v e n t s t h e s u c c e s s f u l a n a l y s i s o f t h e a n a l y t e o r when t h e heterogeneous n a t u r e o f t h e sample p r e c l u d e s t h e use o f d u p l i c a t e analyses.

9.4.8

Where r e f e r e n c e m a t e r i a l s a r e a v a i l a b l e , t h e y s h o u l d be analyzed t o p r o v i d e a d d i t i o n a l performance d a t a . The a n a l y s i s o f r e f e r e n c e samples i s a v a l u a b l e t o o l f o r d e m o n s t r a t i n g t h e a b i l i t y t o p e r f o r m t h e method a c c e p t a b l y .

The f o l l o w i n g t e s t can be used t o assess p o s s i b l e m a t r i x i n t e r f e r e n c e e f f e c t s and t h e need t o complete t h e sample a n a l y s i s by method o f s t a n d a r d a d d i t i o n s (MSA). R e s u l t s o f t h i s t e s t s h o u l d not be c o n s i d e r e d c o n c l u s i v e u n l e s s t h e d e t e r m i n e d sample background absorbance i s < 1.0. D i r e c t i o n s f o r MSA a r e g i v e n i n S e c t i o n 11.5. 9.5.1

10.0

A n a l y t e a d d i t i o n t e s t : An a n a l y t e s t a n d a r d added t o a p o r t i o n o f a p r e p a r e d sample, o r i t s d i l u t i o n , should be r e c o v e r e d t o w i t h i n 85% t o 115% o f t h e known v a l u e . The a n a l y t e a d d i t i o n may be added d i r e c t l y t o sample i n t h e f u r n a c e and s h o u l d produce a minimum l e v e l absorbance o f 0.1. The c o n c e n t r a t i o n o f t h e a n a l y t e a d d i t i o n p l u s t h a t i n t h e sample s h o u l d n o t exceed t h e l i n e a r c a l i b r a t i o n range o f t h e a n a l y t e . If the analyte i s n o t recovered w i t h i n t h e s p e c i f i e d l i m i t s , a m a t r i x e f f e c t s h o u l d be suspected and t h e sample must be analyzed by MSA ( S e c t . 11.5).

CALIBRATION AND STANDARDIZATION 10.1 S p e c i f i c wavelengths and i n s t r u m e n t o p e r a t i n g c o n d i t i o n s a r e l i s t e d i n T a b l e 2. However, because o f d i f f e r e n c e s among makes and models o f spectrophotometers and e l e c t r o t h e r m a l f u r n a c e d e v i c e s , t h e a c t u a l i n s t r u m e n t c o n d i t i o n s s e l e c t e d may v a r y f r o m t h o s e l i s t e d . 10.2 P r i o r t o t h e use o f t h i s method t h e i n s t r u m e n t o p e r a t i n g c o n d i t i o n s must be o p t i m i z e d . The a n a l y s t s h o u l d f o l l o w t h e i n s t r u c t i o n s p r o v i d e d by t h e m a n u f a c t u r e r w h i l e u s i n g t h e c o n d i t i o n s l i s t e d i n Table 2 as a g u i d e . O f p a r t i c u l a r importance i s t h e d e t e r m i n a t i o n o f Revision 2.2 Nay 1994

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the charring temperature limit for each analyte. This limit is the furnace temperature setting where a loss in analyte will occur prior to atomization. This limit should be determined by conducting char temperature profiles for each analyte and when necessary, in the matrix of question. The charring temperature selected should minimize background absorbance while providing some furnace temperature variation without loss of analyte. For routine analytical operation the charring temperature is usually set at least 100°C below this limit. The optimum conditions selected should provide the lowest reliable MDLs and be similar to those listed in Table 2. Once the optimum operating conditions are determined, they should be recorded and avai 1 able for dai ly reference. 10.3 Prior to an initial calibration the linear dynamic range of the analyte must be determined (Sect. 9.2.2) using the optimized instrument operating conditions (Sect. 10.2). For all determinations allow an instrument and hollow cathode lamp warm up period of not less than 15 min. If an EDL is to be used, allow 30 min for warm up. 10.4 Before using the procedure (Sect. 11.0) to analyze samples, there must

be data available documenting initial demonstration of performance. The required data and procedure are described in Section 9.2. This data must be generated using the same instrument operating conditions and calibration routine (Sect. 11.4) to be used for sample analysis. These documented data must be kept on file and be available for review by the data user. 10.5 In order to meet or achieve lower MDLs than those listed in Table 2 for "direct analysis" of drinking water with turbidity < 1 NTU preconcentration of the analyte is required. This may be accomplished prior to sample introduction into the GFAA or with the use of multiple aliquot depositions on the GFAA platform or associated delayed atomization device. When using multiple depositions, the same number of equal volume aliquots alike of either the calibration standards or acid preserved samples must be deposited prior to atomization. Following each deposition the drying cycle is completed before the next subsequent deposition. The matrix modifier is added along with each deposition and the total volume of each deposition must not exceed the instrument manufactures recommended capacity of the delayed atomization device. To reduce analysis time the minimum number of depositions required to achieve the desired analytical result should be used. Use o f this procedural technique for the "direct analysis" of drinking water must be completed using determined optimized instrument operating conditions for multiple depositions (Sect.lO.2) and comply with the method requirements described in Sections 10.3 and 10.4. (See Table 3 for information and data on the determination of arsenic by this procedure.) 11.0 PROCEDURE 11.1 Aqueous Sample Preparation - Dissolved Analytes

11.1.1 For the determination of dissolved analytes in ground and surface waters, pipet an aliquot ( 2 20 mL) of the filtered,


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Methods for the Determination a c i d p r e s e r v e d sample i n t o a 50-mL p o l y p r o p y l e n e c e n t r i f u g e t u b e . Add an a p p r o p r i a t e volume o f (ltl) n i t r i c a c i d t o a d j u s t t h e a c i d c o n c e n t r a t i o n o f t h e a l i q u o t t o approximate a 1% ( v / v ) n i t r i c a c i d s o l u t i o n ( e . g . , add 0.4 mL (ltl) HNO, t o a 20 mL a l i q u o t o f sample). Cap t h e t u b e and m i x . The sample i s now ready f o r a n a l y s i s ( S e c t . 1 . 3 ) . Allowance f o r sample d i l u t i o n should be made i n t h e c a l c u l a t i o n s .

NOTE:

I f a p r e c i p i t a t e i s formed d u r i n g a c i d i f i c a t i o n , t r a n s p o r t , o r s t o r a g e , t h e sample a l i q u o t must be t r e a t e d u s i n g t h e procedure d e s c r i b e d i n S e c t i o n s 11.2.2 t h r u 11.2.7 p r i o r t o a n a l y s i s .

11.2 Aqueous Sample P r e p a r a t i o n - T o t a l Recoverable A n a l y t e s 11.2.1 F o r t h e " d i r e c t a n a l y s i s " o f t o t a l r e c o v e r a b l e a n a l y t e s i n d r i n k i n g w a t e r samples c o n t a i n i n g t u r b i d i t y < 1 NTU, t r e a t an u n f i l t e r e d a c i d p r e s e r v e d sample a l i q u o t u s i n g t h e sample p r e p a r a t i o n procedure d e s c r i b e d i n S e c t i o n 11.1.1 w h i l e making allowance f o r sample d i l u t i o n i n t h e d a t a c a l c u l a t i o n (Sects. 1.2 & 1.4). For the determination o f t o t a l recoverable a n a l y t e s i n a l l o t h e r aqueous samples f o l l o w t h e procedure g i v e n i n S e c t i o n s 11.2.2 t h r o u g h 11.2.7.

11.2.2 For t h e d e t e r m i n a t i o n o f t o t a l r e c o v e r a b l e a n a l y t e s i n aqueous samples ( o t h e r t h a n d r i n k i n g w a t e r w i t h < 1 NTU t u r b i d i t y ) , t r a n s f e r a 100-mL ( ? 1 mL) a l i q u o t f r o m a w e l l mixed, a c i d p r e s e r v e d sample t o a 250-mL G r i f f i n beaker (Sects. 1.2, & 1.6). (When necessary, s m a l l e r sample a l i q u o t volumes may be used. )

NOTE:

I f t h e sample c o n t a i n s u n d i s s o l v e d s o l i d s > 1%, a w e l l mixed, a c i d p r e s e r v e d a l i q u o t c o n t a i n i n g no more t h a n 1 g p a r t i c u l a t e m a t e r i a l s h o u l d be c a u t i o u s l y evaporated t o near 10 mL and e x t r a c t e d u s i n g t h e a c i d m i x t u r e procedure d e s c r i b e d i n S e c t i o n s 11.3.3 t h r u

11.3.6. 11.2.3 Add 2 mL

(ltl) n i t r i c a c i d and 1.0 mL o f (1t1) h y d r o c h l o r i c a c i d t o t h e beaker c o n t a i n i n g t h e measured volume o f sample. P l a c e t h e beaker on t h e h o t p l a t e f o r s o l u t i o n e v a p o r a t i o n . The h o t p l a t e s h o u l d be l o c a t e d i n a fume hood and p r e v i o u s l y adjusted t o provide evaporation a t a temperature o f a p p r o x i m a t e l y b u t no h i g h e r t h a n 85OC. (See t h e f o l l o w i n g note.) The beaker s h o u l d be covered w i t h an e l e v a t e d watch g l a s s o r o t h e r necessary s t e p s s h o u l d be t a k e n t o p r e v e n t sample c o n t a m i n a t i o n from t h e fume hood environment.

NOTE:

For proper heating a d j u s t t h e temperature c o n t r o l o f t h e h o t p l a t e such t h a t an uncovered G r i f f i n beaker c o n t a i n i n g 50 rnL o f w a t e r p l a c e d i n t h e c e n t e r o f t h e h o t p l a t e can be m a i n t a i n e d a t a t e m p e r a t u r e a p p r o x i m a t e l y b u t no h i g h e r t h a n 85'C. (Once t h e beaker Revision 2.2 May 1994

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i s covered w i t h a watch g l a s s t h e temperature o f t h e w a t e r w i l l r i s e t o a p p r o x i m a t e l y 95OC.)

11.2.4

Reduce t h e volume o f t h e sample a l i q u o t t o about 20 mL by g e n t l e h e a t i n g a t 85°C. DO NOT BOIL. T h i s s t e p t a k e s about 2 h f o r a 100 mL a l i q u o t w i t h t h e r a t e o f e v a p o r a t i o n r a p i d l y i n c r e a s i n g as t h e sample volume approaches 20 mL. ( A spare beaker c o n t a i n i n g 20 mL o f w a t e r can be used as a gauge.)

11.2.5

Cover t h e l i p o f t h e beaker w i t h a watch - g l a s s t o reduce a d d i t i o n a l e v a p o r a t i o n and g e n t l y r e f l u x t h e sample f o r 30 m i n u t e s . ( S l i g h t b o i l i n g may occur, b u t v i g o r o u s b o i l i n g must be avoided t o p r e v e n t l o s s o f t h e HC1-H,O a z e o t r o p e . )

11.2.6 A l l o w t h e beaker t o c o o l . Q u a n t i t a t i v e l y t r a n s f e r t h e sample s o l u t i o n t o a 50-mL v o l u m e t r i c f l a s k , make t o volume w i t h r e a g e n t w a t e r , s t o p p e r and mix. 11.2.7 A l l o w any u n d i s s o l v e d m a t e r i a l t o s e t t l e o v e r n i g h t , o r c e n t r i f u g e a p o r t i o n o f t h e p r e p a r e d sample u n t i l c l e a r . ( I f a f t e r c e n t r i f u g i n g o r s t a n d i n g o v e r n i g h t t h e sample c o n t a i n s suspended s o l i d s t h a t would c l o g o r a f f e c t t h e sample i n t r o d u c t i o n system, a p o r t i o n o f t h e sample may be f i l t e r e d f o r t h e i r removal p r i o r t o a n a l y s i s . However, c a r e s h o u l d be e x e r c i s e d t o a v o i d p o t e n t i a l c o n t a m i n a t i o n from f i l t r a t i o n . ) The sample i s now r e a d y f o r a n a l y s i s . Because t h e e f f e c t s o f v a r i o u s m a t r i c e s on t h e s t a b i l i t y o f d i l u t e d samples cannot be c h a r a c t e r i z e d , a l l analyses s h o u l d be performed as soon as p o s s i b l e a f t e r t h e completed p r e p a r a t i o n . 11.3 S o l i d Sample P r e p a r a t i o n - T o t a l Recoverable A n a l y t e s 11.3.1 For t h e d e t e r m i n a t i o n o f t o t a l r e c o v e r a b l e a n a l y t e s i n s o l i d samples, m i x t h e sample t h o r o u g h l y and t r a n s f e r a p o r t i o n ( > 20 g ) t o t a r e d w e i g h i n g d i s h , weigh t h e sample and r e c o r d ( F o r samples w i t h < 35% m o i s t u r e a 20 g t h e wet w e i g h t ( W W ) . portion i s sufficient. F o r samples w i t h m o i s t u r e > 35% a l a r g e r a l i q u o t 50-100 g i s r e q u i r e d . ) Dry t h e sample t o a c o n s t a n t w e i g h t a t 6OoC and r e c o r d t h e d r y w e i g h t (DW) f o r c a l c u l a t i o n o f p e r c e n t s o l i d s ( S e c t . 12.6). (The sample i s d r i e d a t 6OoC t o p r e v e n t t h e p o s s i b l e l o s s o f v o l a t i l e m e t a l l i c compounds, t o f a c i l i t a t e s i e v i n g , and t o r e a d y t h e sample f o r g r i n d i n g .) 11.3.2 To achieve homogeneity, s i e v e t h e d r i e d sample u s i n g a 5-mesh p o l y p r o p y l e n e s i e v e and g r i n d i n a m o r t a r and p e s t l e . (The s i e v e , m o r t a r and p e s t l e s h o u l d be c l e a n e d between samples.) From t h e d r i e d , ground m a t e r i a l weigh a c c u r a t e l y a r e p r e s e n t a t i v e 1.0 f 0.01 g a l i q u o t (W) o f t h e sample and t r a n s f e r t o a 250-mL P h i l l i p s beaker f o r a c i d e x t r a c t i o n ( S e c t . 1.6). 11.3.3 To t h e beaker add 4 mL o f ( l t l ) HNO, and 10 mL o f ( 1 t 4 ) HC1. Cover t h e l i p o f t h e beaker w i t h a watch g l a s s . Place t h e Revision 2.2 Nay 1994

172

Methods for the Determination beaker on a h o t p l a t e f o r r e f l u x e x t r a c t i o n o f t h e a n a t y t e s . The h o t p l a t e s h o u l d be l o c a t e d i n a fume hood and p r e v i o u s l y adjusted t o provide a r e f l u x temperature o f approximately 95OC. (See t h e f o l l o w i n g n o t e . ) NOTE:

F o r proper heating adjust the temperature c o n t r o l o f t h e h o t p l a t e such t h a t an uncovered G r i f f i n beaker c o n t a i n i n g 50 mL o f w a t e r p l a c e d i n t h e c e n t e r o f t h e h o t p l a t e can be m a i n t a i n e d a t a temperature a p p r o x i m a t e l y b u t no h i g h e r t h a n 85'C. (Once t h e beaker i s covered w i t h a watch g l a s s t h e t e m p e r a t u r e o f t h e w a t e r w i l l r i s e t o a p p r o x i m a t e l y 95OC.) A l s o , a b l o c k d i g e s t e r capable o f m a i n t a i n i n g a t e m p e r a t u r e o f 95OC and equipped w i t h 250-mL c o n s t r i c t e d v o l u m e t r i c d i g e s t i o n tubes may be s u b s t i t u t e d f o r t h e h o t p l a t e and c o n i c a l beakers i n t h e e x t r a c t i o n s t e p .

Very s l i g h t 11.3.4 Heat t h e sample and g e n t l y r e f l u x f o r 30 min. b o i l i n g may o c c u r , however v i g o r o u s b o i l i n g must be avoided t o Some s o l u t i o n p r e v e n t l o s s o f t h e HC1-H 0 azeotrope. evaporation w i l l occur ( 3 t o mL).

5

11.3.5 A l l o w t h e sample t o c o o l and q u a n t i t a t i v e l y t r a n s f e r t h e e x t r a c t t o a 100-mL v o l u m e t r i c f l a s k . D i l u t e t o volume w i t h r e a g e n t w a t e r , s t o p p e r and m i x . 11.3.6 A l l o w t h e sample e x t r a c t s o l u t i o n t o s t a n d o v e r n i g h t t o separate i n s o l u b l e m a t e r i a l o r c e n t r i f u g e a p o r t i o n o f the sample s o l u t i o n u n t i l c l e a r . (If a f t e r centrifuging o r s t a n d i n g o v e r n i g h t t h e e x t r a c t s o l u t i o n c o n t a i n s suspended s o l i d s t h a t would c l o g o r a f f e c t t h e sample i n t r o d u c t i o n system, a p o r t i o n o f t h e e x t r a c t s o l u t i o n may be f i l t e r e d f o r t h e i r removal p r i o r t o a n a l y s i s . However, c a r e should be e x e r c i s e d t o a v o i d p o t e n t i a l c o n t a m i n a t i o n from f i l t r a t i o n . ) The sample e x t r a c t i s now r e a d y f o r a n a l y s i s . Because t h e e f f e c t s o f v a r i o u s m a t r i c e s on t h e s t a b i l i t y o f d i l u t e d samples cannot be c h a r a c t e r i z e d , a l l analyses s h o u l d be performed as soon as p o s s i b l e a f t e r t h e completed p r e p a r a t i o n . 11.4 Sample A n a l y s i s 11.4.1 P r i o r t o d a i l y c a l i b r a t i o n o f t h e i n s t r u m e n t i n s p e c t t h e g r a p h i t e f u r n a c e , t h e sample u p t a k e system and autosampler i n j e c t o r f o r any change i n t h e system t h a t would a f f e c t i n s t r u m e n t performance. Clean t h e system and r e p l a c e t h e g r a p h i t e t u b e and/or p l a t f o r m when needed o r on a d a i l y b a s i s . 11.4.2 B e f o r e b e g i n n i n g d a i l y c a l i b r a t i o n t h e i n s t r u m e n t system should be r e c o n f i g u r e d t o t h e s e l e c t e d o p t i m i z e d o p e r a t i n g c o n d i t i o n s as determined i n S e c t i o n s 10.1 and 10.2 o r 10.5 f o r t h e " d i r e c t a n a l y s i s " d r i n k i n g w a t e r w i t h t u r b i d i t y < 1 NTU. I n i t i a t e d a t a system and a l l o w a p e r i o d o f n o t l e s s t h a n 15 min f o r i n s t r u m e n t and h o l l o w cathode lamp warm up. I f an EDL i s t o be used, a l l o w 30 min f o r warm up. Revision 2.2 Hay 1994

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1 1 . 4 . 3 A f t e r t h e warm up p e r i o d b u t b e f o r e c a l i b r a t i o n , i n s t r u m e n t s t a b i l i t y must be demonstrated by a n a l y z i n g a s t a n d a r d s o l u t i o n w i t h a c o n c e n t r a t i o n 20 tiiiies t h e I D L a minimum o f f i v e t i m e s . l h e r e s u l t i n g r e l a t i v e standard d e v i a t i o n (RSD) o f absorbance s i g n a l s must be < 5%. I f t h e RSD i s > 5%, d e t e r m i n e and c o r r e c t t h e cause b e f o r e c a l i b r a t i n g t h e i n s t r u m e n t .

1 1 . 4 . 4 For i n i t i a l and d a i l y o p e r a t i o n c a l i b r a t e t h e i n s t r u m e n t a c c o r d i n g t o t h e i n s t r u m e n t m a n u f a c t u r e r ' s recommended procedures u s i n g t h e c a l i b r a t i o n b l a n k ( S e c t . 7.10.1) and c a l i b r a t i o n standards ( S e c t . 7 . 9 ) p r e p a r e d a t t h r e e o r more c o n c e n t r a t i o n s w i t h i n t h e u s a b l e l i n e a r dynamic range o f t h e a n a l y t e ( S e c t s . 4.4 & 9 . 2 . 2 ) . 11.4.5 An autosampler must be used t o i n t r o d u c e a l l s o l u t i o n s i n t o t h e g r a p h i t e furnace. Once t h e standard, sample o r QC s o l u t i o n p l u s t h e m a t r i x m o d i f i e r i s i n j e c t e d , the furnace c o n t r o l l e r completes f u r n a c e c y c l e s and c l eanout p e r i o d as programmed. A n a l y t e s i g n a l s must be i n t e g r a t e d and c o l l e c t e d as peak area measurements. Background absorbances, background c o r r e c t e d a n a l y t e s i g n a l s , and determined a n a l y t e c o n c e n t r a t i o n s on a l l s o l u t i o n s must be a b l e t o be d i s p l a y e d on a CRT f o r immediate r e v i e w by t h e a n a l y s t and be a v a i l a b l e as h a r d copy f o r documentation t o be k e p t on f i l e . F l u s h t h e autosampler s o l u t i o n u p t a k e system w i t h t h e r i n s e b l a n k ( S e c t . 7.10.4) between each s o l u t i o n i n j e c t e d . 11.4.6 A f t e r c o m p l e t i o n o f t h e i n i t i a l r e q u i r e m e n t s o f t h i s method ( S e c t s . 10.4), samples s h o u l d be analyzed i n t h e same o p e r a t i o n a l manner used i n t h e c a l i b r a t i o n r o u t i n e . 11.4.7 D u r i n g t h e a n a l y s i s o f samples, t h e l a b o r a t o r y must comply w i t h t h e r e q u i r e d q u a l i t y c o n t r o l d e s c r i b e d i n S e c t i o n s 9.3 and 9.4. Only f o r t h e d e t e r m i n a t i o n o f d i s s o l v e d a n a l y t e s or t h e " d i r e c t a n a l y s i s " o f d r i n k i n g w a t e r w i t h t u r b i d i t y o f < 1 NTU i s t h e sample d i g e s t i o n s t e p o f t h e LRB, LFB, and LFM n o t r e q u i r e d . 11.4.8 For e v e r y new o r unusual m a t r i x , when p r a c t i c a l , i t i s h i g h l y recommended t h a t an i n d u c t i v e l y coupled plasma atomic e m i s s i o n s p e c t r o m e t e r be used t o screen f o r h i g h element c o n c e n t r a t i o n . I n f o r m a t i o n g a i n e d from t h i s may be used t o p r e v e n t p o t e n t i a l damage t o t h e i n s t r u m e n t and t o b e t t e r e s t i m a t e which elements may r e q u i r e a n a l y s i s by g r a p h i t e f u r n a c e . 11.4.9 Determined sample a n a l y t e c o n c e n t r a t i o n s t h a t a r e 90% o r more o f t h e upper l i m i t o f c a l i b r a t i o n must e i t h e r be d i l u t e d w i t h a c i d i f i e d r e a g e n t w a t e r and r e a n a l y z e d w i t h concern f o r memory e f f e c t s ( S e c t . 4 . 4 ) , o r determined by a n o t h e r approved t e s t procedure t h a t i s l e s s s e n s i t i v e . Samples w i t h a background absorbance > 1 . 0 must be a p p r o p r i a t e l y d i l u t e d w i t h a c i d i f i e d r e a g e n t w a t e r and r e a n a l y z e d ( S e c t . 9 . 4 . 6 ) . I f t h e method o f standard a d d i t i o n s i s required, f o l l o w the i n s t r u c t i o n s described i n Section 11.5. Revision 2.2 May 1994

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1 1 . 4 . 1 0 When i t i s necessary t o assess an o p e r a t i v e m a t r i x i n t e r f e r e n c e (e.g.! s i g n a l r e d u c t i o n due t o h i g h d i s s o l v e d s o l i d s ) , t h e t e s t d e s c r i b e d i n S e c t i o n 9 . 5 i s recommended. 11.4.11

Report d a t a as d i r e c t e d i n S e c t i o n 1 2 .

1 1 . 5 Standard A d d i t i o n s - I f t h e method o f s t a n d a r d a d d i t i o n i s r e q u i r e d , t h e f o l l o w i n g procedure i s recommended: 1 1 . 5 . 1 The s t a n d a r d a d d i t i o n technique" i n v o l v e s p r e p a r i n g new standards i n t h e sample m a t r i x by adding known amounts o f s t a n d a r d t o one o r more a l i q u o t s o f t h e processed sample s o l u t i o n . T h i s t e c h n i q u e compensates f o r a sample c o n s t i t u e n t t h a t enhances o r depresses t h e a n a l y t e s i g n a l , t h u s p r o d u c i n g a d i f f e r e n t s l o p e f r o m t h a t o f t h e c a l i b r a t i o n s t a n d a r d s . It w i l l n o t c o r r e c t f o r a d d i t i v e i n t e r f e r e n c e , which causes a b a s e l i n e s h i f t . The s i m p l e s t v e r s i o n o f t h i s t e c h n i q u e i s t h e s i n g l e - a d d i t i o n method. The procedure i s as f o l l o w s : Two i d e n t i c a l a l i q u o t s o f t h e sample s o l u t i o n , each o f volume V , a r e t a k e n . To t h e f i r s t ( l a b e l e d A) i s added a small volume b, o f a s t a n d a r d a n a l y t e s o l u t i o n o f c o n c e n t r a t i o n C,. To t h e second ( l a b e l e d B) i s added t h e same volume V, o f t h e s o l v e n t . The a n a l y t i c a l s i g n a l s o f A and B a r e measured and c o r r e c t e d f o r nonanalyte s i g n a l s . The unknown sample c o n c e n t r a t i o n C, i s c a l c u l ated :

where, S and S, a r e t h e a n a l y t i c a l s i g n a l s ( c o r r e c t e d f o r t h e b l a n k ) o f s o l u t i o n s A and B, r e s p e c t i v e l y . V, and C, s h o u l d be chosen so t h a t S, i s r o u g h l y t w i c e S, on t h e average. It i s b e s t i f V, i s made much l e s s t h a n V,, and t h u s C i s much g r e a t e r t h a n C, t o a v o i d excess d i l u t i o n o f t h e sampfe m a t r i x . If a s e p a r a t i o n o r c o n c e n t r a t i o n s t e p i s used, t h e a d d i t i o n s a r e b e s t made f i r s t and c a r r i e d t h r o u g h t h e e n t i r e procedure. F o r t h e r e s u l t s f r o m t h i s t e c h n i q u e t o be v a l i d , t h e f o l l o w i n g 1 i m i t a t i o n s must be t a k e n i n t o c o n s i d e r a t i o n :

1.

The a n a l y t i c a l c u r v e must be l i n e a r .

2.

The chemical f o r m o f t h e a n a l y t e added must respond i n t h e same manner as t h e a n a l y t e i n t h e sample.

3.

The i n t e r f e r e n c e e f f e c t must be c o n s t a n t o v e r t h e w o r k i n g range o f concern.

4.

The s i g n a l must be c o r r e c t e d f o r any a d d i t i v e i n t e r f e r e n c e .


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12.0 DATA ANALYSIS AND CALCULATIONS 1 2 . 1 Sample d a t a s h o u l d be r e p o r t e d i n u n i t s o f pg/L f o r aqueous samples and mg/kg d r y w e i g h t f o r s o l i d samples. 12.2 F o r d i s s o l v e d aqueous a n a l y t e s ( S e c t . 1 1 . 1 ) r e p o r t t h e d a t a generated d i r e c t l y from t h e i n s t r u m e n t w i t h a l l o w a n c e f o r sample d i l u t i o n . Do n o t r e p o r t a n a l y t e c o n c e n t r a t i o n s below t h e I D L . 12.3 For t o t a l r e c o v e r a b l e aqueous a n a l y t e s ( S e c t . 11.2), m u l t i p l y s o l u t i o n a n a l y t e c o n c e n t r a t i o n s by t h e d i l u t i o n f a c t o r 0.5, when 100 mL a l i q u o t i s used t o produce t h e 50 mL f i n a l s o l u t i o n , round t h e d a t a t o t h e t e n t h s p l a c e and r e p o r t t h e d a t a i n pg/L up t o t h r e e s i g n i f i c a n t f i g u r e s . I f a d i f f e r e n t a l i q u o t volume o t h e r t h a n 100 mL i s used f o r sample p r e p a r a t i o n , a d j u s t t h e d i l u t i o n f a c t o r a c c o r d i n g l y . Also, account f o r any a d d i t i o n a l d i l u t i o n o f t h e prepared sample s o l u t i o n needed t o complete t h e d e t e r m i n a t i o n o f a n a l y t e s exceeding t h e upper l i m i t o f t h e c a l i b r a t i o n curve. Do n o t r e p o r t d a t a below t h e determined a n a l y t e MDL c o n c e n t r a t i o n o r below an a d j u s t e d d e t e c t i o n 1 i m i t r e f l e c t i n g s m a l l e r sample a1 i q u o t s used i n p r o c e s s i n g o r a d d i t i o n a l d i l u t i o n s r e q u i r e d t o complete t h e a n a l y s i s . 12.4 For t o t a l r e c o v e r a b l e a n a l y t e s i n s o l i d samples ( S e c t . 11.3), round t h e s o l u t i o n a n a l y t e c o n c e n t r a t i o n s ( p g / L ) t o t h e t e n t h s p l a c e . Report t h e d a t a up t o t h r e e s i g n i f i c a n t f i g u r e s as mg/kg d r y - w e i g h t b a s i s u n l e s s s p e c i f i e d o t h e r w i s e by t h e program o r d a t a u s e r . C a l c u l a t e t h e c o n c e n t r a t i o n u s i n g t h e e q u a t i o n below: C x V x D Sample Conc. (mg/kg) dry-weight basis

=

W

where: C = C o n c e n t r a t i o n i n e x t r a c t (pg x O.OOl/L) V = Volume o f e x t r a c t (L, 100 mL = 0.1L) D = D i l u t i o n f a c t o r ( u n d i l u t e d = 1) W = Weight o f sample a l i q u o t e x t r a c t e d ( g x 0.001 = kg) Do n o t r e p o r t a n a l y t e d a t a below t h e e s t i m a t e d s o l i d s MDL o r an a d j u s t e d MDL because o f a d d i t i o n a l d i l u t i o n s r e q u i r e d t o complete t h e analysis.

12.5 To r e p o r t p e r c e n t s o l i d s i n s o l i d samples ( S e c t . 11.3) c a l c u l a t e as f o l 1ows : DW % s o l i d s (S) =

where: DW WW

= =

- x 100

ww

Sample w e i g h t ( 9 ) d r i e d a t 6OoC Sample w e i g h t ( 9 ) b e f o r e d r y i n g Revision 2.2 Hay 1994

176

Methods for the Determination NOTE: If the data user, program or laboratory requires that the

reported percent solids be determined by drying at 105OC, repeat the procedure given in Section 11.3 using a separate portion ( > 20 g) of the sample and dry to constant weight at 103-105°C. 12.6 The QC data obtained during the analyses provide an indication o f the quality of the sample data and should be provided with the sample results. 13.0

BETHOD PERFORMANCE

13.1 Instrument operating conditions used for single laboratory testing of the method and MDLs are listed in Table 2. 13.2 Data obtained from single laboratory testing of the method are summarized in Table 1A-C for three solid samples consisting of SRM 1645 River Sediment, EPA Hazardous Soil, and EPA Electroplating S1 udge. Samples were prepared using the procedure described in Section 11.3. For each matrix, five replicates were analyzed, and an average of the replicates was used for determining the sample background concentration. Two other pairs o f duplicates were fortified at different concentration levels. The sample background concentration, mean spike percent recovery, the standard deviation o f the average percent recovery, and the relative percent difference between the dupl icate-fortified determinations are 1 isted in Table 1AC. In addition, Table 1D-F contains single-laboratory test data for the method in aqueous media including drinking water, pond water, and well water. Samples were prepared using the procedure described in Section 11.2. For each aqueous matrix five replicates were analyzed, and an average of the replicates was used for determining the sample background concentration. Four samples were fortified at the levels reported in Table 1D-1F. A percent relative standard deviation is reported in Table 1D-1F for the fortified samples. An average percent recovery is also reported in Tables 1D-F. NOTE: Antimony and aluminum manifest relatively low percent recoveries (see Table lA, NBS River Sediment 1645).

14.0

POLLUTION PREVENTION

14.1

Pollution prevention encompasses any technique that reduces or eliminates the quantity or toxicity of waste at the point of generation. Numerous opportunities for pollution prevention exist in laboratory operation. The EPA has established a preferred hierarchy of environmental management techniques that places pollution prevention as the management option of first choice. Whenever feasible, laboratory personnel should use pollution prevention techniques to address their waste generation. When wastes cannot be feasibly reduced at the source, the Agency recommends recycling as the next best option.

14.2 For information about pollution prevention that may be applicable to laboratories and research institutions, consult Less i s Better: Revision 2.2 May 1994

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Laboratory Chemical Management for Waste Reduction, available from the American Chemical Society’s Department of Government Relations and Science Policy, 1155 16th Street N.W., Washington D.C. 20036, (202)872-4477. 15.0

WASTE MANAGEMENT 15.1

16.0

The Environmental Protection Agency requires that laboratory waste management practices be conducted consistent with all applicable rule and regulations. The Agency urges laboratories to protect the air, water, and land by minimizing and controlling all releases from hoods and bench operations, complying with the letter and spirit of any sewer discharge permits and regulations, and by complying with all solid and hazardous waste regulations, particularly the hazardous waste identification rules and land disposal restrictions. For further information on waste management consult The Waste Management Manual f o r Laboratory Personnel, available from the American Chemical Society at the address listed in the Section 15.2.

REFERENCES 1.

Environmental Protection Agency. Method 200.9, Determination of Trace Elements by Stabilized Temperature Graphite Furnace Atomic Absorption Spectrometry, Revision 1 . 2 , 1991.

2.

Creed, J.T., T.D. Martin, L.B. Lobring and J.W. O’Dell, Environ. Sci. Technol., 26:102-106, 1992.

3.

Waltz, B., G. Schlemmar and J.R. Mudakavi,

U.S.

JAAS, 3,

695,

1988.

4.

Carcinogens - Working With Carcinogens, Department of Health, Education, and Welfare, Public Health Service, Center for Disease Control, National Institute for Occupational Safety and Health, Publication No. 77-206, Aug. 1977.

5.

OSHA Safety and Health Standards, General Industry, (29 CFR 1910), Occupational Safety and Health Administration, OSHA 2206, (Revised, January 1976).

6.

Safety in Academic Chemistry Laboratories, American Chemical Society Publication, Committee on Chemical Safety, 3rd Edition, 1979.

7.

Proposed OSHA Safety and Health Standards, Laboratories, Occupational Safety and Health Administration, Federal Register, July 24, 1986.

8.

Rohrbough, W.G. et al. Reagent Chemicals, American Chemical Society Specifications, 7th edition. American Chemical Society, Washington, DC, 1986.


178

Methods for the Determination 9.

American Society f o r Testing and M a t e r i a l s . Standard S p e c i f i c a t i o n f o r Reagent Water, D1193-77. Annual Book o f ASTM Standards, V o l . 11.01. P h i l a d e l p h i a , PA, 1991.

10.

Code o f Federal Regulation N , Ch. 1, P t . 136, Appendix B.

11.

Winefordner, J . D . , Trace Analysis: Spectroscopic Elements, Chemical Analysis, V o l . 4 6 , pp. 41-42.

Methods f o r


17.0 TABLES, DIAGRAMS. FLOWCHARTS. AND V A L I D A T I O N DATA

TABLE 1A.

Sol i d Sample

A1 umi num A n t i mony Arsenic Cadmi um Chromi urn Copper Manganese Sel en i um Si 1 ver Tin

Certified Value+ 22600

(51) (66) 10.2 29600 109 785 1.5 --

--

Average Sed Conc (mg/kg) 6810 25.8 69.2 10.8 32800 132 893 0.7 1.7 439

P R E C I S I O N AND RECOVERY DATA FOR NBS R I V E R SEDIMENT 1645

% RSD

4.6 8.2 3.4 3.7 1.6 4.8 5.1 20.4 3.1 4.4

Average Percent Recovery (20 mg/kg)x

* 74.9 69.8 115.3

*

99.1

*

96.0 101.8 --

S(r)

-8.3 19.0 2.6 -14.2 -15.9 3.8

--

RPD

-9.5 12.0 4.0 -0

-45.2 9.7

--

Average Percent Recovery (100 rng/kg)x

* 99.0 89.2 110.7

*

111.5 103.2 105.4 93.5 --

S(r)

RPD

__

__

1.5 4.3 0.7

2.7 7.3 1.7

__

-_

3.6 26.4 4.0 1.9 --

2.6 4.7 10.7 5.6 --

( n = 5) S ( r ) Standard Deviation of Average Percent Recovery RPD Relative Percent Difference Between Duplicate Recovery Determinations * F o r t i f i e d concentration t10% o f sample concentration -Not determined t Values in parenthesis a r e noncertified X F o r t i f i e d concentration

% RSD Percent Relative Standard Deviation

FE m

0

rt

Average Sed Conc (mg/kg)

S o l i d Sample A1 umi num Ant imony Arsenic Cadmi um Chromi urn Copper Manganese Sel e n i um S i 1v e r Tin

1

6410 4.6 8.7 1.8 84.0 127 453 0.6 0.9 18.4


% RSD

3.3 14.7 4.6 10.3 4.2 4.3 6.0 7.5 18.5 3.7

S(r)

RPD

--

--

61.4 109.8 115.4 95.5 108.0

2.7 2.1 0.8 33.8 15.2

7.4 3.5 1.4 17.9 2.6

95.0 100.1

8.4 3.8

*

*

I

--

--

-_


*

--

24.1 10.2

--

I

% RSD Percent R e l a t i v e Standard D e v i a t i o n ( n = 5)

S ( r ) Standard D e v i a t i o n of Average Percent Recovery RPD

*

-X

R e l a t i v e Percent D i f f e r e n c e Between D u p l i c a t e Recovery D e t e r m i n a t i o n s F o r t i f i e d c o n c e n t r a t i o n (10% o f sample c o n c e n t r a t i o n Not determined F o r t i f i e d concentration

60.9 103.7 99.0 120.8 117.7 99.2 96.9 93.5 --

9 0 S(r)

-1.7 1.5 4.3 6.6 5.4 13.9 3.3 1.3

--

RPD

-7.1 3.6 12.1 8.9 5.7 1.6 9.7 3.8

--

?!

$.

Fig.

TABLE 1C.

PRECISION AND RECOVERY DATA FOR EPA ELECTROPLATING SLUDGE 286

Solid Sample

A1 umi num Antimony Arsenic Cadmi um Chromi um Copper Manganese Selenium Si 1 ver Tin % RSD S(r)

RPD

*

-X

zz 6590 7.7 33.7 119 8070 887 3 20 0.8 6.5 21.8

%

RSD 2.7 3.9 2.7 1.3 4.5 1.6 1.6 6.7 2.3 3.2


* 68.6 87.6 81.9

* * *

99.4 102.8

--

S(r)

RPD

--

--

2.3 2.6 7.9

----

0.8 2.5

--

1

Average Percent ( RecovgerYg)x 100 m /k

*

5.7 1.7 3.0

60.7 100.2 112.5

2.3 5.3

99.5 101.0 96.8 92.3

-_--

--

Percent !lative StanLJrd wiation (n = 5) Standard Deviation o f Average Percent Recovery Relative Percent Difference Between Duplicate Recovery Determinations Fortified concentration 4 0 % o f sample concentration Not determined Fortified concentration

*

--

S(r)

RPD

--

--

3.1 1.5 3.9

--

21.9 6.4 0.7 1.9

--

12.8 3.1 4.7

--

6.0 4.0 1.9 5.4

--

TABLE 1D.

Element Ag

A1

As3

Be Cd co Cr cu Fe Mn

Ni Pb Sb3 se3 sn3

T1

Average Conc. pg/L t0.5 550 3.2 0.05 to. 05 t0.7 0.75 2.98 773 751 2.11 1.22 4 t0.8 t0.6 t1.7 t0.7

PRECISION AND RECOVERY DATE FOR POND WATER

% RSD

Fort i f ied, Conc. pg/L

* 1.2 4.1 36.4

* *

8.7 11.2 5.7 2.2 6.8 20.5

* *

* 75.0

% RSD at Fortifipd Conc.

1.25

--

lo 2.5 0.5 10 2.5 10 --20 25 25 25 50 50

Recovery

3.7 -0.8 14.0 4.5 2.8 1.8 2.9 --

--

1.6 1.8 0.4 1.6 3.3 5.2

< Sample concentration less than the established method detection limit.

* Not determined on sample concentrations less than the method detection limit.

' Fortified sample concentration based on 100-mL ' RSD are reported on 50-mL sample volumes. Electrodeless discharge lamps were used.

sample volumes.

107.5 -100.5 90.0 99.1 97.3 98.5 101.9

--

-105.6 101 -6 115.2 97.8 117.5 101.0

TABLE 1E.

E l ement

Average Conc. pg/L

Ag A1 As3 Be Cd

co Cr cu Fe Mn

Ni Pb Sb3 s e3 sn3 T1 t

PRECISION AND RECOVERY DATE FOR DRINKING NATER

t0.5 163.6 0.5 t0.02 to. 05 2 t i m e s t h e 1X MDL) e n v i r o n m e n t a l c o n t a m i n a t i o n i s suspected. 13.2 Data o b t a i n e d f r o m s i n g l e l a b o r a t o r y t e s t i n g o f t h e method a r e summarized i n Table 6 f o r f o u r d i f f e r e n t d r i n k i n g w a t e r s u p p l i e s ( t w o ground w a t e r s and two s u r f a c e w a t e r s ) and an ambient s u r f a c e w a t e r . The p r e c i s i o n and r e c o v e r y d a t a were c o l l e c t e d by simultaneous ICP-AES u t i l i z i n g t h e recommended wavelengths g i v e n i n Table 1 and t h e i n s t r u m e n t c o n d i t i o n s l i s t e d i n T a b l e 5. The u n f i l t e r e d d r i n k i n g w a t e r s were p r e p a r e d u s i n g t h e procedure d e s c r i b e d i n S e c t i o n 11.1 w h i l e t h e t o t a l r e c o v e r a b l e procedure ( S e c t s . 11.2.2 -11.2.7) was used t o p r e p a r e t h e ambient s u r f a c e w a t e r . F o r each m a t r i x , f i v e r e p l i c a t e a l i q u o t s were prepared, analyzed and t h e average o f t h e f i v e d e t e r m i n a t i o n s used t o d e f i n e t h e sample background c o n c e n t r a t i o n o f each a n a l y t e . I n a d d i t i o n , two f u r t h e r p a i r s o f d u p l i c a t e s were f o r t i f i e d a t d i f f e r e n t c o n c e n t r a t i o n l e v e l s . F o r each method a n a l y t e , t h e sample background c o n c e n t r a t i o n , mean p e r c e n t r e c o v e r y , t h e s t a n d a r d d e v i a t i o n o f t h e p e r c e n t r e c o v e r y and t h e r e 1 a t i v e p e r c e n t d i f f e r e n c e between t h e d u p l i c a t e f o r t i f i e d samples a r e l i s t e d i n T a b l e 6. The v a r i a n c e o f t h e f i v e r e p l i c a t e sample background d e t e r m i n a t i o n s i s included i n t h e c a l c u l a t e d standard d e v i a t i o n o f the percent r e c o v e r y when t h e a n a l y t e c o n c e n t r a t i o n i n t h e sample was g r e a t e r t h a n t h e MDL. F o r t i f i e d sample d a t a f o r t h e m a t r i x a n a l y t e s Cay K, Mg, Na, S r , and SiO, a r e n o t i n c l u d e d . However, t h e p r e c i s i o n and mean sample background c o n c e n t r a t i o n s f o r t h e s e s i x a n a l y t e s a r e 1 i s t e d s e p a r a t e l y i n Table 7 .

14.0 POLLUTION PREVENTION

1 4 . 1 P o l l u t i o n p r e v e n t i o n encompasses any t e c h n i q u e t h a t reduces o r e l i m i n a t e s t h e q u a n t i t y o r t o x i c i t y o f waste a t t h e p o i n t o f g e n e r a t i o n . Numerous o p p o r t u n i t i e s f o r p o l l u t i o n p r e v e n t i o n e x i s t i n l a b o r a t o r y o p e r a t i o n . The EPA has e s t a b l i s h e d a p r e f e r r e d h i e r a r c h y o f e n v i r o n m e n t a l management t e c h n i q u e s t h a t p l a c e s p o l l u t i o n p r e v e n t i o n as t h e management o p t i o n o f f i r s t c h o i c e . Whenever f e a s i b l e , 1 a b o r a t o r y personnel s h o u l d use p o l l u t i o n p r e v e n t i o n t e c h n i q u e s t o address t h e i r waste g e n e r a t i o n (e.g., S e c t . 7.9). When wastes cannot be f e a s i b l y reduced a t t h e source, t h e Agency recommends r e c y c l i n g as t h e n e x t b e s t o p t i o n . 14.2 F o r i n f o r m a t i o n about p o l l u t i o n p r e v e n t i o n t h a t may be a p p l i c a b l e t o l a b o r a t o r i e s and r e s e a r c h i n s t i t u t i o n s , c o n s u l t l e s s i s B e t t e r : L a b o r a t o r y Chemical Management f o r I l a s t e R e d u c t i o n , a v a i l a b l e f r o m t h e American Chemical S o c i e t y ' s Department o f Government R e l a t i o n s and Science P o l i c y , 1155 1 6 t h S t r e e t N . W . , Washington D.C. 20036, (202)872-4477.

R e v i s i o n 1 . 2 May1994

Metals

277

15.0 WASTE MANAGEMENT 15.1 The Environmental P r o t e c t i o n Agency r e q u i r e s t h a t l a b o r a t o r y waste management p r a c t i c e s be conducted c o n s i s t e n t w i t h a l l a p p l i c a b l e r u l e s and r e g u l a t i o n s . The Agency urges l a b o r a t o r i e s t o p r o t e c t t h e a i r , w a t e r , and l a n d by m i n i m i z i n g and c o n t r o l l i n g a l l r e l e a s e s f r o m hoods and bench o p e r a t i o n s , complying w i t h t h e l e t t e r and s p i r i t o f any sewer d i s c h a r g e p e r m i t s and r e g u l a t i o n s , and by complying w i t h a l l s o l i d and hazardous waste r e g u l a t i o n s , p a r t i c u l a r l y t h e hazardous waste i d e n t i f i c a t i o n r u l e s and l a n d d i s p o s a l r e s t r i c t i o n s . For f u r t h e r i n f o r m a t i o n on waste management c o n s u l t The Waste Management Manual f o r l a b o r a t o r y P e r s o n n e l , a v a i l a b l e f r o m t h e American Chemical S o c i e t y a t t h e address l i s t e d i n t h e S e c t i o n 1 4 . 2 . 16.0 REFERENCES 1.

U.S. Environmental P r o t e c t i o n Agency. I n d u c t i v e l y Coupled Plasma Atomic Emission S p e c t r o m e t r i c Method f o r Trace Element A n a l y s i s o f Water and Wastes - Method 200.7, V e r s i o n 3 . 3 , 1991.

2.

U.S. Environmental P r o t e c t i o n Agency. I n d u c t i v e l y Coupled Plasma Atomic Emission Spectrometry Method f o r t h e A n a l y s i s o f Waters and S o l i d s , EMMC, J u l y 1992.

3.

Boumans, P.W.J.M. L i n e Coincidence Tables f o r I n d u c t i v e l y Coupled Plasma Atomic Emission Spectrometry, 2nd e d i t i o n . Pergamon Press, Oxford, U n i t e d Kingdom, 1984.

4.

e t a l . I n d u c t i v e l y Coupled Plasma-Atomic Emission Winge, R.K. Spectroscopy: An A t l a s o f S p e c t r a l I n f o r m a t i o n , P h y s i c a l Science Data 20. E l s e v i e r Science P u b l i s h i n g , New York, New York, 1985.

5.

M a r t i n , T.D., C.A. B r o c k h o f f and J.T. Creed. Trace Metal Valence S t a t e C o n s i d e r a t i o n i n U t i l i z i n g an U l t r a s o n i c N e b u l i z e r f o r Metal Determination by ICP-AES. Winter Conference on Plasma S p e c t r o c h e m i s t r y , San Diego, CA, January, 10-15, 1994.

6.

Carcinogens - Working W i t h Carcinogens, Department o f H e a l t h , E d u c a t i o n , and W e l f a r e , P u b l i c H e a l t h S e r v i c e , Center f o r Disease C o n t r o l , N a t i o n a l I n s t i t u t e f o r O c c u p a t i o n a l S a f e t y and H e a l t h , P u b l i c a t i o n No. 77-206, Aug. 1977.

7.

OSHA S a f e t y and H e a l t h Standards, General I n d u s t r y , (29 CFR 1910), O c c u p a t i o n a l S a f e t y and H e a l t h A d m i n i s t r a t i o n , OSHA 2206, (Revised, January 1976).

8.

S a f e t y i n Academic Chemistry L a b o r a t o r i e s , American Chemical S o c i e t y Pub1 i c a t i o n , Committee on Chemical S a f e t y , 3 r d E d i t i o n , 1979.

9.

Proposed OSHA S a f e t y and H e a l t h Standards, L a b o r a t o r i e s , Occupational S a f e t y and H e a l t h A d m i n i s t r a t i o n , Federal R e g i s t e r , J u l y 24, 1986.

R e v i s i o n 1 . 2 May1994

278

Methods for the Determination 10.

Rohrbough, W.G. e t a l . Reagent Chemicals, American Chemical S o c i e t y S p e c i f i c a t i o n s , 7 t h e d i t i o n . American Chemical S o c i e t y , Washington, DC, 1986.

11.

American S o c i e t y f o r T e s t i n g and M a t e r i a l s . Standard S p e c i f i c a t i o n f o r Reagent Water, 01193-77. Annual Book o f ASTM Standards, Vol. 11.01. P h i l a d e l p h i a , PA, 1991.

12.

Code o f Federal R e g u l a t i o n s 40, Ch. 1, P t . 136 Appendix B.

13.

Wallace, G.F., Some F a c t o r s A f f e c t i n g t h e Performance o f an I C P Sample I n t r o d u c t i o n System. Atomic Spectroscopy, V o l . 4, p . 188-192, 1983.

14.

K o i r t y o h a n n , S.R. e t a l . Nomenclature System f o r t h e Low-Power Argon I n d u c t i v e l y Coupled Plasma, Anal. Chem. 2 : 1 9 6 5 , 1980

15.

Deming, S.N. and S . L . Morgan. Experimental Design f o r Q u a l i t y and P r o d u c t i v i t y i n Research, Development, and M a n u f a c t u r i n g , P a r t 111, pp 119-123. S h o r t c o u r s e pub1 i c a t i o n by S t a t i s t i c a l Designs, 9941 R o w l e t t , S u i t e 6, Houston, TX 77075, 1989.

16.

Winefordner, J.D., Trace A n a l y s i s : Spectroscopic Elements, Chemical A n a l y s i s , V o l . 46, pp. 41-42.

Methods

for

R e v i s i o n 1.2 May1994

Metals

279

17.0 TABLES, DIAGRAMS. FLOWCHARTS, AND VALIDATION DATA TABLE 1.

Anal y t e

WAVELENGTHS, ESTIMATED INSTRUMENT DETECTION LIMITS, AND RECOMMENDED CALIBRATION Wave1 engtha (nm)

Detection Lirni tb (P9/L)

C a l i brate' to (mg/L)

~

A1 urni nurn Ant imony Arsenic B a r i urn B e r y l 1 iurn Boron Cadrni urn Calcium Cer iurn Chromium Cobalt Copper Iron Lead Lithium Magnesi urn Manganese Mercury Mol ybdenurn Nickel Pot ass iurn Sel en iurn S i l i c a (SiO,) S i 1v e r Sodi urn S t r o n t i urn Thal 1 iurn Tin Titanium Vanadi urn Zinc

308.215 206.833 193.759 493.409 313.042 249.678 226.502 315.887 413.765 205.552 228.616 324.754 259.940 220.353 670.784 279.079 257.610 194.227 203.844 231.604 766.491 196.090 251.611 328.068 588.995 421.552 190.864 189.980 334.941 292.402 213.856

1 1

3 0.2 0.05 2 0.2 1 20 0.9 0.4 0.3 0.3 2 0.4 2 0.2 3 1 0.8 40 8 10 (SiO,)

2 1 2 0.2 0.2 0.5 0.5 40 0.5 1 0.5 0.5 2 2 1 10 0.5 0.5 2 0.5 10 2 2

0.3

0.1

3 0.1 5 4 0.1 0.6 0.4

20 0.2 1 1 2 0.5 1

a The wavelengths l i s t e d a r e recommended because o f t h e i r s e n s i t i v i t y and

o v e r a l l a c c e p t a b i l i t y . O t h e r wavelengths may be s u b s t i t u t e d i f t h e y can p r o v i d e t h e needed s e n s i t i v i t y and a r e t r e a t e d w i t h t h e same c o r r e c t i v e t e c h n i q u e s f o r s p e c t r a l i n t e r f e r e n c e (see S e c t i o n 4.1). The 1i s t e d EMSL-Cincinnati e s t i m a t e d 3-sigma i n s t r u m e n t a l d e t e c t i o n l i m i t s a r e p r o v i d e d o n l y as a g u i d e t o i n s t r u m e n t a l l i m i t s . C

Suggested c o n c e n t r a t i o n f o r i n s t r u m e n t c a l i b r a t i o n .

Other c a l i b r a t i o n

l i m i t s i n t h e l i n e a r ranges may be used.

R e v i s i o n 1 . 2 May1994

280

Methods for the Determination TABLE 2. ON-LINE METHOD INTERELEMENT SPECTRAL INTERFERENCES ARISING FROM INTERFERANTS AT THE 20-mg/L LEVEL

Analyte Ag A1 As B Ba Be Ca Cd Ce co Cr cu Fe Hg K Li Mg Mn Mo Na Ni Pb

Sb Se SiO, Sn Sr T1

Ti V Zn

Wavelength (nm) 328.068 308.215 193.759 249.678 493.409 313.042 315.887 226.502 413.765 228.616 205.552 324.754 259.940 194.227 766.491 670.784 279.079 257.610 203.844 588.995 231.604 220.353 206.833 196.099 251.611 189.980 421.552 190.864 334.941 292.402 213.856

I n t e rferant* Ce,Ti ,Mn V,Mo,Ce,Mn V,A1 ,Co,Fe,Ni None None V,Ce Co,Mo, Ce Ni,Ti,Fe,Ce None Ti,Ba,Cd,Ni,Cr,Mo,Ce Be,Mo,Ni, Mo,Ti None V,Mo None None Ce Ce Ce None Co, T1 Co,A1 ,Ce,Cu,Ni , T i ,Fe Cr,Mo,Sn,Ti,Ce,Fe Fe None Mo,Ti,Fe,Mn,Si None Ti,Mo,Co,Ce,Al,V,Mn None Mo,Ti,Cr,Fe,Ce N i ,Cu,Fe

* These o n - l i n e i n t e r f e r e n c e s from method a n a l y t e s and t i t a n i u m o n l y were observed u s i n g an i n s t r u m e n t w i t h 0.035-nm r e s o l u t i o n (see Sect. 4.1.2). I n t e r f e r a n t ranked by magnitude o f i n t e n s i t y w i t h t h e most severe i n t e r f e r a n t l i s t e d f i r s t i n t h e row.

R e v i s i o n 1 . 2 May1994

Metals

281

TABLE 3. NIXED STANDARD SOLUTIONS' Sol ut 1 on

I I1 I11

IV V VI

Anal ytes Ag, As, B y Ba, Cd, Cu, Mn, and Sb K , Li, Mo, Sr, and Ti C o y V, and Ce Al, Cry Hg, SiO,, Sn, and Zn Be, F e y Ni, Pb, and T1 Se, C a y Mg,and Na

'

See Table 1 for recommended calibration concentrations. See Sections 1.10 and 4.3 for discussion on desolvation affects on A s , Cr, and Se. See Section 7.10 and 7.11 for preparation o f calibration standard and blank solutions.


282


TABLE 4 .

Analyte

METHOD DETECTION

1X MDL D i r e c t Analysis, pg/L

(MDL)")

LIMITS

2X MDL Total Recoverable Digestion, pg/L'*'

Ag A1

0.6

As

3

2

B Ba

2

4 0.2

0.6

4

20

0.2

Be Cd Ce co

Cr cu

0.05

0.02

0.4

0.2

5 0.6 2

0.4

5 0.4

2 2 3

Fe Hg Li Mn

0.7 10 2

0.7 0.09

0.9 0.08

Mo Ni

2

1

0.7

Pb

4

0.8 2

Sb* Se

3

3 3

5

Sn Sr

2 0.2

5

0.08

Ti T1

0.2

V

6 2

Zn

0.5

1X MDL. mq/L

Ca K

Mg Na SiO,

0.3 2 0.5 0.7 2x

MDL. mq/LC2'

0,005 0.09 0.005

0.03 0.05

0.04

0.05 0.03

0.002

0.01

(1)

Method detection limits are sample dependent and may vary as the sample matrix varies.

(2)

MDL concentrations are computed for original matrix with allowance for 2x sample preconcentration during preparation. Samples were processed in PTFE and diluted in 50-mL plastic centrifuge tubes.

*

Se MDL determined in tap water due to common matrix enhancement (Sect. 1.10) Revision1.2 May1994

Metals TABLE 5.

283

INDUCTIVELY COUPLED PLASMA AND ULTRASONIC NEBULIZER INSTRUMENT OPERATING CONDITIONS

ICP SPECTROMETER I n c i d e n t r f power

1400 w a t t s

R e f l e c t e d r f power

< 5 watts

Viewing h e i g h t above work c o i l I n j e c t o r tube o r i f i c e i.d. Argon s u p p l y

15 mm 1 mm

l i q u i d argon

Argon p r e s s u r e

40 p s i

C o o l a n t argon f l o w r a t e

19 L/min

Auxi 1 ia r y ( p l asma) argon f l o w r a t e

300 mL/min

ULTRASONIC NEBULIZER Aerosol c a r r i e r argon flow rate

570 mL/min

Sample u p t a k e r a t e c o n t r o l 1 ed t o

1.8 mL/min

Transducer power 1.4 MHz auto-tuned Desolvation temperature Condenser t e m p e r a t u r e

35 w a t t s 14OoC 5OC

R e v i s i o n 1.2 May 1994

284


TABLE 6.

P R E C I S I O N AND RECOVERY DATA

IN

AQUEOUS MATRICES

REGION 2 - TAP WATER

SAMPLE CONC pG/L

HIGH SPIKE pG/L

AVERAGE RECOVERY R(%)

100 400 300 200

104 105 112 95 101

0.3 0.8 0.9 0.6 0.4

0.6 1.2 1.6

0.3 0.4

500 200 200

103 105 103 104 106

0.2

0.6 0.7 0.9 0.7 0.3

4.1 2.7 2.3

200 200 300 200 100

103 105 107 102 104

0.7 0.7 0.3 0.4 0.5

0.6 0.8 0.6 0.6 0.9

3.3 0.4 8.8 0.3 1.9

6.8 0.6 4.9 0.6 4.0

200 100 400 300 500

101 105 109 110 107

0.3 0.2 0.4 0.5 1.2

0.5 0.4 0.6 1.0 2.3

1.2 1.3 1.6 2.0 1.2

2.4 2.5 2.7 3.9 0.5

400 200 400 200 200

107 104 109 102 110

0.1 0.4 0.1 1 :2 0.6

0.2 0.7 0.2 2.3 1 .o

pG/L

AVERAGE RECOVERY R(%)

S(R)

RPD

t0.6 10.4 t3 5.3 5.8

10.0 40.0 30.0 20.0 20.0

114 115 118 94 100

2.0 3.8 0.7 3.8 1.6

3.5 0.4 1.1 0.8 2.4

Be Cd Ce co Cr

to.05

t0.4

Methods for the Determination of Metals in Environmental Samples

Methods for Phase Diagram Determination

Methods for Phase Diagram Determination

Methods for Phase Diagram Determination

Analysis of pesticides in food and environmental samples

Determination of Metals in Natural and Treated Waters

Methods in Environmental Forensics

Mathematical methods for the Magnetohydrodynamics of Liquid Metals

Methods for Environmental Trace Analysis

Methods for Environmental Trace Analysis

Methods for Environmental Trace Analysis

Immunotoxicology Of Environmental And Occupational Metals

A Man Of Samples

Methods of testing concrete: Determination of the modulus of rupture

Artificial Intelligence Methods in the Environmental Sciences

Machine Learning Methods in the Environmental Sciences

Methods of Environmental Impact Assessment

Assessment of an ultramicroelectrode array UMEA) sensor for the determination of trace concentrations of heavy metals in water

Liquid Chromatography for the Determination of Mycotoxins in Foods

Metals for Biomedical Devices

Separation Methods for Waste and Environmental Applications

Environmental Economics, Experimental Methods

Environmental and genetic determination of population dynamics (RUS)

Methods of testing concrete: Method for the determination of bleeding of concrete

The Experimental Determination of Solubilities

Quality Assurance in Environmental Monitoring: Instrumental Methods

Environmental Degradation of Metals: Corrosion Technology Series 14

Theory of Orbit Determination

Supported metals in catalysis

Methods for the Determination of Metals in Environmental Samples

Methods for Phase Diagram Determination

Methods for Phase Diagram Determination

Methods for Phase Diagram Determination

Analysis of pesticides in food and environmental samples

Determination of Metals in Natural and Treated Waters

Methods in Environmental Forensics

Mathematical methods for the Magnetohydrodynamics of Liquid Metals

Methods for Environmental Trace Analysis

Methods for Environmental Trace Analysis

Methods for Environmental Trace Analysis

Immunotoxicology Of Environmental And Occupational Metals

A Man Of Samples

Methods of testing concrete: Determination of the modulus of rupture

Artificial Intelligence Methods in the Environmental Sciences

Machine Learning Methods in the Environmental Sciences

Methods of Environmental Impact Assessment

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