JOURNAL OF CHROMATOGRAPHY LIBRARY
- volume21
environmental problem solving using gas and liquid chromatography
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JOURNAL OF CHROMATOGRAPHY LIBRARY
- volume21
environmental problem solving using gas and liquid chromatography
JOURNAL OF CHROMATOGRAPHY LIBRARY Volume 1
Chromatography of Antibiotics, by G.H. Wagman and M.J. Weinstein
Volume 2
Extraction Chromatography, edited by T. Braun and G. Ghersini
Volume 3
Liquid Column Chromatography. A Survey of Modern Techniques end Applications, edited by 2.Deyl, K. Mecek end J. J a d k
Volume 4
Detectors in Gas Chromatography, by J.Sev'Eik
Volume 5
Instrumental Liquid Chromatography. A Practical Manual on High-Performance Liquid Chromatographic Methods, by N.A. Parris
Volume 6
Isotachophorsis. Theory, Instrumentation end Applications, by F.M. Evereerts, J.L. Backers end Th.P.E.M. Verheggen
Volume 7
Chemical Derivetization in Liquid Chromatography, by J.F. Lawrence and R.W. Frei
Volume 8
Chromatography of Steroids, by E. Heftmann
Volume 9
HPTLC - High Performance Thin-Layer Chrometogaphy, edited by A. Zlatkis and R.E. Kaiser
Volume 10
Gas Chromatography of Polymers, by V.G. Berezkin, V.R. Alishoyev and I.B. Nemlrovskaya
Volume 11
Liquid Chromatography Detectors, by R.P.W. Scott
Volume 12 Affinity Chromatography,
by J.
Turkovd
Volume 13
Instrumentation for HighPerformance Liquid Chromatography,edited by J.F.K. Huber
Volume 14
Radiochromatography.The Chromatography and Electrophoresis of Radiolabl led Compounds, by T.R. Roberts
Volume 15
Antibiotics, Isolation, Separation and Purification, edited by M.J. Weinstein and G. H. Wagman
Volume 16
Porous Silica. I t s Properties and Use as Support in Column Liquid Chromatography, by K.K. Unger
Volume 17
76 Years of Chromatography - A Historical Dialogue, edited by L.S. Ettre and A. Zlatkis
Volume 18
Electrophoresis. A Survey of Techniques and Applications. Pert A: Techniques, edited by 2. Deyl
Volume 19
Chemical Derivatization in Gas Chromatography, by J. Drozd
Volume 20
Electron Capture. Theory and Practice in Chromatography, edited by A. Zletkis and C.F. Poole
Volume 21
Environmental Problem Solving using Gas and Liquid Chromatography, by R.L. Grob and M.A. Kaiser
JOURNAL OF CHROMATOGRAPHY LIBRARY - volume 21
environmental problem solving using gas and liquid chromatography
Robe/t L. Grob Professor of Analytical Chemistry, Villanova University, Villanova,PA 19085
Mary A. Kaiser Supedsor, Separations Group, Central Research and Development Department, E. I. du Pont de Nemours & Co., Experimental Station, Wilmington, DE 19898
ELSEVIER SCIENTIFIC PUBLISHING COMPANY Amsterdam - Oxford - New York 1982
ELSEVIER SCIENCE PUBLISHERS B.V. Sara Burgerhartstraat 25 P.O. Box 21 1,1000 AE Amsterdam, The Netherlands Distributors for the United States and Canada: ELSEVIER SCIENCE PUBLISHING COMPANY INC. 52, Vanderbilt Avenue New York, N Y 10017
First edition 1982 Second impression 1985
ISBN 0-444-42065-7(Val. 21) ISBN 0-444-41616-1 (Series)
0 Elsevier Science Publishers B.V., 1982 All rights reserved. No part o f this publication may be reproduced, stored i n a retriewl system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publisher, Elsevier Science Publishers B.V./Science & Technology Division, P.O. Box 330,1000 A H Amsterdam, The Netherlands.
Special regulations for readers in the USA - This publication has been registered with t h e Copyright Clearane Center Inc. (CCC), Salem, Massachusetts. Information can be obtained from the CCCabout conditions under which photocopies of parts of this publication may be made in the USA, All other copyright questions, including photocopying outside of the USA, should be referred t o the publisher. Printed in The Netherlands
V C ONTE NTS
................................................................... I X SCOPE OF THE PROBLEM....................................................... 1 1. 1.1 H i s t o r y and Backqround ..................................................... 1 1.2 M e t h o d b l o g i c a l Q i e s t ions ......... ......................................... 4 ......................................... 6 REFERENCES ....................... 2 . CRITERIA FOR THE SAMPLING PROCESS ......................................... 1 2.1 Requirements ..................... ......................................... 7. 2.1.1 General D i s c u s s i o n ........ ......................................... 2.1.2 C r i t e r i a f o r Sampling ..... .......................................... 9 10 Sample Types and Sanipl i n g Problem ................................... 2.1.3 2.2 Problems o f Sampling and Post-Samples ...................................... 12 13 2.3 R e g u l a t i o n s ................................................................ 14 2.4 Standards .................................................................. 2.4.1 O j s c u s s i o n .......................................................... 14 Preface
1
.....................
2.4.2 A v a i l a b i l i t y and Source o f Samples and S u p p l i e s REFERENCES................................................................. 3
.
3.1 3.2
16 22
................................... .................... 25 I n t r o d u c t i o n .......................................... .................... 25 Background and General D i s c u s s i o n ..................... .................... 26 3.2.1 Theory and S t a t i s x i c a l F o u n d a t i o n o f Sampling .. .................... 29 S i g n i f i c a n c e and R e j e c t i o n o f Data .... .................... 3.2.1.1 35 R e l i a b i l i t y and/or Confidence i n Analy i c a l Data ...........36 3.2.1.2 3.2.2 A e r o s o l s ........................... ................................ 3.2.3 Gases and Vapors ................... ................................ 40 3.2.3.1 Flow Measurements ......... ................................ 41 3.2.3.2 Volume Neasurements ....... ................................ 42 ................................ 42 3.2.4 L i q u i d s ............................ 3.2.5 Sampling P r o p o r t i o n a l t o Time and F ow .............................. 43 3.2.6 S o l i d s ............................. ................................ 44 3.2.6.1 S o i l s ..................... ................................ 45 3.2.6.2 P a r t i c u l a t e s ............................................... 46 49 Grab Sampl ing .............................................................. A i r ................................................................. 49 3.3.1 3.3.2 L i q u i d s ............................................................. 54 55 3.3.2.1 Composite Sampling ......................................... SAMPLING TECHNIQUES
77 J I
3.3
3.,1 3.5 3.6 3.7 3.8 3.9
........................................ ...................................................... ...................................................... ............................................................... ............................................................... ............................................... ......................................... ........................................................ ....................................... .........................................................
3.3.2.2 Continuous Sampling 3.3.3 Stack Sampling A d s o r p t i o n Techniques 3.4.1 Gases 3.4.2 Water Chemical R e a c t i o n Techniques Freeze-Out o r Cryogenic Techniques T r a p p i n g Techniques D i p p i n g Techniques and Tube Sampling Headspace Sampl i n g REFERENCES
56 56 59 6.. 0 68 69 72 74 77 78 79
................................................................ 4 . SAMPLE TREATMENT ............ ..............................................
87
................ .............................................. .......... ..............................................
a7 87
............................................
91
4.1 4.2 4.3
Introduction Storage o f Samples E x t r a c t i o n Techniques 4.3.1 L i q u i d - L i q u i d E x t r a c t on
....... ..............................................
aa
VI
...........................
4.4 4.5 5
.
5.1 5.2 5.3
5.4 5.5 5.6
5.7
4.3.1.1 Macro-Liquid-Liquid Extractions 4.3.1.2 Micro-Liquid-Liquid Extractions 4.3.2 Gas-Liquid E x t r a c t i o n 4.3.2.1 Headspace a n d / o r Vapor E q u i l i b r a t i o n 4.3.2.1.1 P r e p a r a t i o n o f Gas S t a n d a r d M i x t u r e s 4.3.2.1.2 E r r o r I n v o l v e d When P r e p a r i n g a B i n a r y Gas Mixture 4.3.2.2 P u r g i n g . S p a r g i n g a n d / o r Vapor S t r i p p i n g 4.3.2.3 Change i n I o n i c S t r e n g t h o f Sample S o l u t i o n Clean-up Derivatization REFERE~ICES
................................................................ USE OF LIQUID CHROrlATOGRAPHY IN ENVIRONMENTAL AIIALYSIS .................... Standards and C a l i b r a t i o n ................................................. Sample I n t r o d u c t i o n Onto t h e Column ....................................... REFERENCES
G. 6.1 6.2 6.3
91
........................... 94 .............................................. 95 ...................... 9 8 ........... 108 ........................................ 109 .................. 109 ...............111 .................................................................. 112 ............................................................ 120 ................................................................ 129 THE USE OF GAS CHROMATOGRAPHY IN ElJVIROfIMEI.ITAL ANALYSIS ................... 137 I n t r o d u c t i o n .............................................................. 137 137 Standards and C a l i b r a t i o n ................................................. 5.2.1 Volume Measurement and Standards f o r A i r Samples ................... 141 5.2.2 Volume Measurement and Standards f o r Water Samples .................147 147 Sample I n t r o d u c t i o n Onto t h e Column ....................................... 5.3.1 S y r i n g e I n j e c t i o n .................................................. 149 149 5.3.2 Gas Sampling Valves ................................................ 150 5.3.3 Automatic Sample I n j e c t i o n ......................................... 150 5.3.4 M i s c e l l a n e o u s I n j e c t i o n Systems .................................... Columns and Column S e l e c t i o n f o r S e p a r a t i o n and A n a l y s i s ..................151 154 D e t e c t i o n o f Sample Components ............................................ Q u a l i t a t i v e and Q u a n t i t a t i v e I n f o r m a t i o n .................................. 157 Q u a l i t a t i v e A n a l y s i s by Gas Chromatography ......................... 157 5.6.1 5.6.1.1 R e t e n t i o n Data ............................................ 158 159 5.6.1.2 R e t e n t i o n I n d e x ........................................... 160 5.6.1.3 A u x i l i a r y Techniques ...................................... 161 5.6.2 Q u a n t i t a t i v e A n a l y s i s by Gas Chromatography ........................ 165 A n a l y s i s o f A i r and Water c o n t a m i n a n t s ....................................
.................................................. .................................................... ........................................ .............................................. ............................................
6.2.1 Syringe I n j e c t i o n 6.2.2 Valve I n j e c t i o n Selection o f Separation Conditions 6.3.1 Water S o l u b l e Samples 6.3.2 Organic S o l u b l e Samples 6.3.3 Thin-Layer chromatography (TLC) S c r e e n i n g 6.3.4 Guard Columns and Precolumns 6.3.5 A p p l i c a t i o n s D e t e c t i o n o f Sample Components 6.4.1 R e f r a c t i v e Index D e t e c t o r 6.4.2 U l t r a v i o l e t Absorption Detector 6.4.3 LC-GC D e t e c t o r s 6.4.4 I n f r a r e d D e t e c t o r s ................................................. 6.4.5 Fluorescence D e t e c t o r s ............................................. 6.4.6 Electrochemical Detector 6.4.7 Thermal Energy D e t e c t o r ............................................ 6.4.8 C o n d u c t i v i t y D e t e c i o r 6.4.9 Derivatives REFERENCES
171
197 187 187 187 1% 188 190 190 191 191 192 196 1~G 197 197 190 198 198 19D 199 199 ?OD
.......................... .......................................
6.4
....................................................... ............................................ .......................................... .................................... .................................................... ..........................................
..............................................
........................................................
................................................................
VII
7
.
7.1
7.2 7.3
a. 8.1
SAFETY I N THE CHROMATOGRAPHY LABORATORY
...................................
202
....................................................... 202 .............................................................. 202 ...................204 ................................................... 206 ....................................................... 208 ................................................. 208 ....................................................... 210 ......................................................... 211 ................................................ 211 ................................................ 211 ................................ 212 ...................................................... 212 ................................................................ 212 REGULATIONS. REGULATORY AND ADVISORY GROUPS ............................... 213 213 Governmental Agencies. L e g i s l a t i o n . and R e l a t e d Groups .................... 213 8.1.1 I n t e r n a t i o n a l O r g a n i z a t i o n s ............. .......................... Hazardous M a t e r i a l s 7.1.1 Types 7.1.2 Use. D i s p o s a l and S t o r a g e o f Hazardous M a t e r i a l s 7.1.3 Compressed Gases Personal P r o t e c t i o n 7.2.1 P r o t e c t i v e Devices 7.2.2 Housekeeping Safety L i t e r a t u r e Books and P a n p h l e t s 7.3.1 7.3.2 J o u r n a l s and Papers 7.3.3 F i l m s and A u d i o v i s u a l P r e s e n t a t i o n s 7.3.4 Miscellaneous REFEREIICES
.................213 .......................... 213 ..................... 213 .................. .......................... 213 ......................... .......................... 213 .......................... 216 ........................ ........................ .......................... 217 ........................ .......................... 219 ............................... 219
8.2
8.1.1.1 UtlEP ( U n i t e d N a t i o n s Environrnen Program) 8.1.1.2 WHO (World H e a l t h O r g a n i z a t i o n ) CEC ( C o u n c i l o f European Commuti t i e s ) 8.1.1.3 8.1.2 National Organizations 8.1.2.1 Canada 8.1.2.2 Austria 8.1.2.3 Belgium 8.1.2.4 Denniark 8.1.2.5 Federal R e p u b l i c o f Germany 8.1.2.6 France 8.1.2.7 Iceland 8.1.2.8 Ireland 8.1.2.9 Italy 8.1.2.10 Luxembourq 8.1.2.11 The i ~ e t h e r l a n d s 8.1.2.12 Norway 8.1.2.13 Sweden 8.1.2.14 S w i t z e r l a n d 3.1.2.15 Japan 8.1.2.1G U n i t e d S t a t e s o f Anierica 8.1.2.17 U.S.S.R 8.1.2.10 A u s t r a l i a 8.1.2.19 Israel 8.1.2.20 Mexico 8.1.2.21 New Zealand 8.1.2.22 South A f r i c a Literature 8.2.1 S c i e n t i f i c J o u r n a l s and P e r i o d i c a l s 8.2.2 S c i e n t i f i c Books 8.2.3 R e g u l a t o r y I n f o r m a t i o n Sources 8.2.4 O t h e r Sources
.................................................... ................................................... ................................................... ..................................................... ................................................ ........................................... .................................................... .................................................... ............................................... ..................................................... .................................. ................................................... ................................................. .................................................... .................................................... ............................................... .............................................. ................................................................ ................................ .................................................. .................................... .....................................................
220 2?0 220 220 221 221 221 221 221 222 222 2 2 ~ 2.. 226 226 226 226 226 226 228 229 229
APPENDIX I:The D e t e r m i n a t i o n o f A d s o r p t i o n - D e s o r p t i o n E f f i c i e n c y o f Chromatographic Traps ...............................................
231
APPENDIX 1I:Comparison o f Modes o f Sample I n t r o d u c t i o n i n C a p i l l a r y Gas Chromatography ........................................
233
SUBJECT INDEX ...................................................................
235
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IX PREFACE
"A question t o ponder i s t h i s : would t h i s l a r g e 'home' we c a l l t h e e n v i r onment s u r v i v e if we leave i t completely i n t h e hands o f Mother Nature? t h e answer i s yes, does t h i s a l l o w us t o be completely unconcerned?
If
If the
answer i s no, then how f a r should we extend o u r s t u d i e s and safeguards?
The
authors feel t h a t t h i s i s n o t an easy yes o r no question, b u t t h a t t h e answer l i e s i n f i n d i n g an e q u i l i b r i u m somewhere between the two extremes.
Once t h i s
p o i n t o f e q u i l i b r i u m i s found, i t i s simply a m a t t e r o f a d j u s t i n g t h e v a r i ables from time t o time so t h a t we d o n ' t s h i f t t o t h e ' r e a c t a n t ' o r ' p r o d u c t ' Grob, Environmental
sides and become incompatible w i t h t h e system."
(R.L,
Studies o f t h e Atmosphere by Gas Chromatography,
i n Contemporary Topics i n
A n a l y t i c a l and C l i n i c a l Chemistry, D.M, and M.A.
Evenson (Eds.),
Hercules, G.M.
H i e f t j e , L.R.
Snyder,
Plenum Press, New York, 1977)"
Environmental analyses can be j u s t i f i e d f o r many reasons: ( 1 ) considera t i o n o f the p o p u l a t i o n because o f r e s i d e n t i a l atmospheric p o l l u t i o n , ( 2 ) m o n i t o r i n g o f t e c h n i c a l advances t o c o n t r o l p o l l u t i o n , ( 3 ) assessing p l a n t damage and animal i n j u r i e s because o f environmental damage t o our a g r i c u l t u r a l systems,
( 4 ) i d e n t i f y i n g substances which e x p l a i n events o r a c t i v i t i e s
which have taken p l a c e i n t h e environment and ( 5 ) p r e s e r v i n g t h e work areas i n i n d u s t r i e s by d e t e c t i n g harmful components which can be i n j u r i o u s t o personnel.
A i r and water p o l l u t a n t s may be gases, l i q u i d s o r s o l i d s which can change the n a t u r a l composition o f our environment.
A i r p o l l u t a n t s can be c l a s s i f i e d
as emissions i f they escape i n t o t h e o u t s i d e a i r a f t e r being discharged from their pollution site o r
2s
emissions i f t h e y s t a y near t h e s i t e o f generation.
X
I n the United States smog r e s u l t s from c a t a l y s i s by s o l a r r a d i a t i o n o f o l e f i n s and n i t r o g e n oxides, whereas i n Europe most o f t h e smog r e s u l t s from t h e s u l f u r d i o x i d e released by f l u e gases. We can place t h e e f f e c t s o f a i r p o l l u t i o n i n b e t t e r p e r s p e c t i v e i f we
consider t h a t a normal b r e a t h i s approximately 0,5 l i t e r and a deep b r e a t h can be from 1.5 t o 2.0 l i t e r s , o f a i r / d a y ( i - e . 4,2-7.0
L/min).
Thus, on t h e average we i n h a l e about 6-10 m3 The nose, mouth, and t o some e x t e n t t h e
trachea and bronchia w i l l r e t a i n p a r t i c l e s which a r e 5-40 pm i n diameter b u t p a r t i c l e s 0.5-5
pm
t i c l e s l e s s than 5
i n diameter u s u a l l y e n t e r t h e lungs and dre deposited. pm
Par-
( f i n e dusts) a r e u s u a l l y exhaled.
Accuracy o f an environmental a n a l y s i s means i t s correctness.
Sensitivity
r e f e r s t o t h e s m a l l e s t amount o f a contaminant t h a t can be detected w i t h certainty.
I t i s t h e task o f t h e a n a l y t i c a l chemist t o s e l e c t and sometimes
m d i f y t h e method which w i l l be a p p l i e d so t h a t s p e c i f i c requirements o f accuracy and s e n s i t i v i t y are met and r e l e v a n t i n f o r m a t i o n i s obtained.
The
number o f d i f f e r e n t methods a v a i l a b l e are wide i n scope and t h e a p p r o p r i a t e procedure must be choien t o s a t i s f y t h e needs o f t h e problem,
The e n v i r o n -
mental problem may concern p r o p e r t y damage and l e s s e l a b o r a t e sampling p r o cedures and l e s s accurate methods may p r o v i d e t h e i n f o r m a t i o n .
However,
when t h e environmental problem i n v o l v e s a h e a l t h hazard i t i s n o t wise t o a l l o w economic c o n s i d e r a t i o n s t o preclude r e l i a b i l i t y and comprehensiveness. The number o f d i f f e r e n t methods and instruments a v a i l a b l e make i t necessary f o r the a n a l y t i c a l chemist t o choose the c o r r e c t system so t h a t he can p r o duce r e l e v a n t data. The authors have chosen t h e course t h a t sampling per se i s a technique which occurs o u t s i d e the l a b o r a t o r y (i.e.,
o b t a i n i n g a r e p r e s e n t a t i v e por-
t i o n o f the b u l k p o p u l a t i o n ) , whereas any m a n i p u l a t i o n o f t h e sample i n s i d e the l a b o r a t o r y f a l l s i n t o t h e realm o f sample treatment.
'
As a consequence
o f t h i s d e c i s i o n , headspace (vapor e q u i l i b r a t i o n ) sampling f i t s more
XI
a p p r o p r i a t e l y i n t o sample t r e a t m e n t , i.e.,
i n t h e g e n e r a l c a t e g o r y o f ex-
t r a c t i o n t r e a t m e n t o f l a b o r a t o r y samples.
We r e a l i z e t h a t a number o f r e a d e r s
and w o r k e r s i n t h e f i e l d o f e n v i r o n m e n t a l a n a l y s i s w i l l n o t a g r e e w i t h t h i s c a t e g o i i z a t i o n ; however, i t does have i t s m e r i t s . (1)
I t removes t h e o v e r l a p o r g r e y area o f what i s a c t u a l l y s a m p l i n g i n
t h e t r u e sense and sample t r e a t m e n t ,
(2)
I t c l e a r l y e s t a b l i s h e s t h e f a c t t h a t w h a t one does w i t h t h e " r e p r e -
s e n t a t i v e " sample i n t h e l a b o r a t o r y i s r e a l l y " p r e p a r i n g " i t f o r a n a l y s i s ,
(3)
When t h e a n a l y t i c a l c h e m i s t p e r f o r m s "headspace sampling,"
"vapor
e q u i l i b r a t i o n , " a n d / o r "purge and t r a p " t e c h n i q u e s he i s o n l y t r e a t i n g a sample t h a t must be r e p r e s e n t a t i v e o f t h e b u l k p o p u l a t i o n of sample a v a i l a b l e t o him,
A l l w r i t t e n works c e r t a i n l y have s h o r t c o m i n g s "
Nothing i s p e r f e c t i n t h e
w o r l d o f r e a l i t y , and a n y t h i n g t h a t endeavors t o be a b s o l u t e l y i d e a l c o u l d n e v e r be completed
Our completed work, i t s s t y l e o r o v e r a l l f o r m a t w i l l
n o t f i l l t h e r e q u i r e m e n t s o f a l l persons.
One w r i t e s what h e c o n s i d e r s t h e Construct-
best manuscript t o serve the m a j o r i t y o f the intended readership.
i v e comients a r e s o l i c i t e d , b u t we r e c o g n i z e t h a t agreement among a l l i s impossible
.
The c o n i p l e t i o n o f a w r i t t e n work i s n o t p o s s i b l e w i t h o u t t h e a s s i s t a n c e and comnents o f o t h e r s who a r e q u a l i f i e d t o r e v i e w t h e m a n u s c r i p t .
The
a u t h o r s w i s h t o thank t h e i r r e s p e c t i v e spouses, C e c i l (MAK) and Marge (RLG) f o r b e i n g u n d e r s t a n d i n g d u r i n g t h e t i m e t h i s was b e i n g w r i t t e n .
We a l s o
w i s h t o thank D r . G e r a l d R. U m b r e i t f o r r e a d i n g and commenting on a number o f c h a p t e r s and Norman Henry 111 and Joseph V i s k o c i l f o r t h e i r comnents o n c h a p t e r 7,
We a p p r e c i a t e t h e a s s i s t a n c e o f Mary Ann Q u a r r y , Mary E l l e n
McNal l y , Proespichaya Kanatharana, and S i t h i c h a i L e e p i p a t p i b o o n i n p r o o f r e a d i n g t h e f i n a l copy.
To D r . C e c i l Oybowski go o u r s p e c i a l t h a n k s f o r
h i s valuable e d i t o r i a l assistance w i t h t h i s manuscript.
We acknowledge
XI1 Linda Grob f o r the i l l u s t r a t i o n s , B e t t y B. Wolfe, Sharon
M. Dize and Dorothy
Lauder f o r s e t t i n g the manuscript i n t o p r i n t and being p a t i e n t w i t h a l l t h e changes and l a s t minute a d d i t i o n s , and f i n a l l y t h e support o f t h e OuPont Company i n t h i s connection.
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CHAPTER I SCOPE OF THE PROBLEM
1.1
HISTORY AND BACKGROUND Environmental problems have burdened mankind s i n c e t h e f i r s t human roamed t h e As technology progressed and man's a p p e t i t e f o r a c a r e f r e e l i f e expanded,
earth.
Lodge ( r e f . 1 )
environmental problems became more complex and d i f f i c u l t t o a l l e v i a t e . suggested t h a t t h e f i r s t a i r - p o l l u t i o n
the
problem may have occurred when a p r e h i s t o r i c
man brought a b u r n i n g branch i n t o h i s cave.
C e r t a i n l y such an event c o u l d have been
viewed as d i s c o m f o r t i n g t o t h e cave's o t h e r occupants who c o u l d have f i l e d t h e f i r s t impact statement on t h e d e s i r a b i l i t y o f b r i n g i n g smoky branches
environmental enclosed areas.
t i o n , a i r p o l l u t i o n and solid-waste d i s p o s a l .
Water p o l l u t i o n has been p r e s e n t longer
than t h e o t h e r two and it i s a more widespread problem.
Modern technology is f i n d i n g
ways t o dispose o f o r use s o l i d waste and t o reduce t h e e f f l u e n t s from s t a c k s and auto-emissions;
however,
into
water p o l l u -
Three c a t e g o r i e s o f p o l l u t i o n a r e our b i g g e s t concern:
industrial
i t i s v e r y expensive t o c l e a n up p o l l u t e d water
and/or f i n d a market f o r i t s p o l l u t a n t s .
I t i s d i f f i c u l t t o i m a g i n e what may have been t h e f i r s t w a t e r - p o l l u t i o n problem.
Perhaps it was associated w i t h t h e n a t u r a l p o l l u t i o n o f l a k e o r r i v e r by an
overgrowth o f p l a n t s o r contamination by human waste. +he book o f
Deuteronomy
(Chapter
23:
Verses
references t o c o n s t r u c t i o n and placement o f
12-14)
sanitary
it is i n t e r e s t i n g t o n o t e t h a t c o n t a i n s one o f f a c i l i t i e s for
the earllest
human waste t o
avoid both a i r and water contamination. F o r y e a r s man used a smal I p e r c e n t a g e of t h e n a t u r a l r e s o u r c e s ( t r e e s , minerals, o r e deposits, animals and f i s h ) a v a i l a b l e t o him. fire,
r a i n , t h e content o f r i v e r s and streams, fish.
The d i s c o v e r y and use o f
disposal o f h i s waste products and work processes had l i t t l e o r no e f f e c t on t h e land erosion,
and l i f e c y c l e s o f animals and
These n a t u r a l resources were able t o r e p l e n i s h themselves because t h e y were I n
greater abundance than man.
The increase i n p o p u l a t i o n and technology has caused a
large s h i f t i n t h i s s i t u a t i o n .
We have disposed o f hundreds o f m i l l i o n s o f t o n s o f
garbage and t r a s h i n t o a few dumps and l a n d f i I I s ,
r e l e a s e d hundreds o f b i l l l o n s o f
g a l l o n s o f waste-containing waters i n t o our streams and r i v e r s and sent hundreds o f m i l l i o n s o f t o n s o f p o l l u t a n t s i n t o our atmosphere. Earth consists of
t h e troposphere
(The atmosphere n e a r s s t t o our
and t h e stratosphere.
The troposphere
i s that
p o r t i o n o f t h e atmosphere from E a r t h ' s surface t o an a l t i t u d e o f seven m i l e s ( 1 1 km); t h e s t r a t o s p h e r e begins a t seven m i l e s and extends t o Earth's surface).
17 m i l e s (27 km)
above t h e
2 F u l l e r ( r e f . 2 ) has presented a unique c o r r e l a t i o n between energy consumption and t h e number o f persons on t h e E d t h .
"The Egyptian pharoahs who b u i I t t h e g r e a t
pyramids commanded t h e labor (energy) o f 100,000 slaves.
The g l o r i e s o f Athens i n i t s
Golden Age were supported by t h e labor o f 125,000 slaves.
L i f e i n the United States
today i s smoothed by t h e energy e q u i v a l e n t t o t h e labor o f 40 b i l l i o n slaves. us
warm,
manufacture
our
goods,
grow
and
process
our
foods,
To keep
transport
these
n e c e s s i t i e s and l u x u r i e s t o our homes, and e n t e r t a i n us i n our l e i s u r e hours, each o f us comnands t h e energy e q u i v a l e n t t o t h e work o f 200 f u l l - t i m e slaves." I t has been estimated ( r e f .
3) that
nonrenewable n a t u r a l resources w i l l
i f our present mode o f
l i f e continues,
become exhausted and t h e death r a t e w i l i
rise
sharply. With t h e onset o f h i g h f o s s i l
fuel
use I n t h e
p o l l u t i o n became a s e r l o u s problem i n urban areas.
13th and 14th c e n t u r i e s ,
air
The f i r s t bans on t h e b u r n i n g o f
coal came d u r i n g t h e r e i n o f E l i z a b e t h I when Parliament banned coal b u r n i n g i n London c i t y l i m i t s w h i l e Parliament was i n session.
As a matter o f f a c t ,
i n most c o u n t r i e s ,
smoke and s o o t p r o b l e m s s p u r r e d t h e f i r s t p o l l u t i o n l e g i s l a t i o n . consumption o f
fossil
f u e l s continues t o
increase.
The r a t e o f
A reasonable e s t i m a t e
i s that
today f o s s i l f u e l i s being used a m i l l i o n times f a s t e r than i t can be formed. Often environmental as t h e
altitude)
l e g i s l a t i o n followed serious a i r - p o i l u t i o n
( r e g i o n s of
inversions
t h e atmosphere where t h e temperature
i n t h e Meuse R i v e r V a l l e y i n Western Europe i n 1930,
i n c i d e n t s such increases w i t h
Donora,
PA i n 1948
(four-day i n v e r s i o n p e r i o d k i l l e d 20 persons and caused more than 7000 persons t o be i l i ) , and i n London i n 1952 (four-day
i n v e r s i o n p e r i o d k i l l e d 4000 persons) ( r e f . 4 ) .
The a i r - p o l l u t i o n
episode i n Donora was one o f t h e most c a r e f u l l y s t u d i e d cases
modern h i s t o r y .
I t took many years o f
in
i n v e s t i g a t i o n and research t o conclude t h a t
z i n c ammonium sui f a t e probably caused t h e i I inesses among 43 o f t h e persons i n t h e Donora area.
The most probable source o f t h e p o l l u t i o n was t h e l o c a l s t e e l and z i n c
p I ants. Many f a c t o r s can e n t e r i n t o a i r - p o l l u t i o n c r i s e s .
I t i s n o t w i t h i n t h e scope
of t h i s book t o d e t a i l a l l o f these except t o say t h a t m e t e o r o l o g i c a l , t o p o g r a p h i c a l and some
light
intensity
factors
play
important
roles.
Earth
rotation
n a t u r a l a i r c i r c u l a t i o n because mountains and canyons d e f l e c t a i r f l o w .
distorts
Clouds and
haze absorb more heat than clean a i r , where a i r becomes warmer over barren ground than a i r over ground w i t h heavy vegetation.
Also a i r over water i s c o o l e r than ground a i r .
A l l these v a r i a b l e s a f f e c t t h e f l o w o f a i r ;
a i r movement i s l i m i t e d .
movement o f weather f r o n t s and mountain b a r r i e r s , reduce t h e u l t r a v i o l e t r a y s o f t h e sun. basin being formed
Due t o t h e slow
l i t t l e cloud cover
This r e s u l t s
i s present t o
i n a huge chemical
i n which photochemical r e a c t i o n s can occur.
Thus,
reaction
i n order t o
minimlze t h e p o t e n t i a l f o r these r e a c t i o n s , one must c o n t r o l t h e t y p e and q u a n t i t y o f e f f l u e n t s i n t h e basin.
3 A c i d r a i n s cause a g r e a t animal
life.
deal
of
damage t o o u r
bui Idings,
soil,
B e l g i u m and The N e t h e r l a n d s have t h e most a c i d i c r a i n
These p r o b a b l y r e s u l t from t h e f a c t t h a t t h e y a r e c e n t r a l l y
plant
and
i n t h e world.
l o c a t e d I n t h e European
i n d u s t r i a l complex. A number o f t e r m s f r e q u e n t l y appear i n t h e a i r - p o l l u t i o n
literature,
p o l l u t a n t 3 r e l e a s e d i n t o t h e atmosphere w i l l
interact with other pollutants,
these
concentration o f
r e a c t i o n s which
example o f
this
determine t h e
phenomenon
is
the
final
classical
formation o f
many
and t h e s e
A number o f
s h o u l d be f a m i l i a r t o t h e s c i e n t i s t w o r k i n g w i t h e n v i r o n m e n t a l p r o b l e m s .
and i t i s
pollutants.
peroxyacylnitrate
An which
o c c u r s when h y d r o c a r b o n s r e a c t w i t h oxygen atoms f r o m t h e d e c o m p o s i t i o n of n i t r o g e n d i o x i d e t o form
free radicals.
These f r e e r a d i c a l s r e a c t w i t h oxygen
and n i t r o g e n
d i o x i d e molecules t o form t h e p e r o x y a c y l n i t r a t e s . The maximum c o n c e n t r a t i o n health ill-effects
of
a p o l l u t a n t allowed
in the a i r
without
causing
The r e s i d e n c e t i m e o f a p o l l u t a n t i s
i s known as t o l e r a n c e l e v e l .
t h e t i m e n e c e s s a r y f o r t h e p o l l u t a n t t o be removed by n a t u r a l p u r i f i c a t i o n p r o c e s s e s . The greenhouse e f f e c t
i s t h e h e a t i n g o f t h e e a r t h ' s atmosphere because t h e atmosphere
t r a n s m i t s t h e v i s i b l e and u l t r a v i o l e t
light
infrared
L a r g e c o n c e n t r a t i o n s of c a r b o n d i o x i d e i n t h e
l i g h t generated a t t h e e a r t h ' s surface. atmosphere w i l I enhance t h i s e f f e c t .
f r o m t h e sun and a b s o r b s t h e
The r e s u l t o f t h i s e f f e c t i s t h a t t h e e a r t h ' s
t e m p e r a t u r e has i n c r e a s e d because t h e average c a r b o n d i o x i d e c o n c e n t r a t i o n has increased during t h e past century. A i r pol l u t a n t s a r e b a s i c a l l y any v o l a t i l e m a t e r i a l s g e n e r a t e d a t t h e E a r t h ' s s u r f a c e ( o x i d e s o f carbon, etc.)
sulfur,
nitrogen:
hydrocarbons:
gaseous m e t a l compounds,
and p a r t i c u l a t e m a t t e r ( a g e n e r a l t e r m w h i c h i n c l u d e s s m a l l s o l i d p a r t i c l e s ,
as
w e l l as l i q u i d d r o p l e t s ) . One o f
our
most
f r a g i l e natural
c o u r s e o f human development,
sources
the availability of
water
supply,
the
i n h a b i t a n t s were
of
Through t h e l o c a t i o n for
d i d not maintain a clean
f o r c e d t o move on t o a new
location.
clean sources of water.
t e c h n o l o g y has made i t p o s s i b l e t o u t i l i z e w a t e r removal
si~pply.
determined t h e
c o n t a m i n a n t s w h i c h cause
The g r o w t h o f
f o r m a n u f a c t u r i n g o f goods and a l s o
human h e a l t h p r o b l e m s .
W h i l e m o s t manu-
f a c t u r e r s acted responsibly i n t h e u t i l i z a t i o n o f t h i s n a t u r a l resource, not.
As t h e
fewer p l a c e s r e m a i n e d t o w h i c h g r o u p s were a b l e t o move,
and i t became i m p e r a t i v e t o m a i n t a i n good,
for
water
I f a settlement
s e t t l e m e n t and programs o f c i v i l i z a t i o n .
p o p u l a t i o n o f t h e e a r t h grew,
i s t h e water
a few d i d
The r e s u l t o f t h e s e i r r e s p o n s i b l e a c t s has been d e t r i m e n t a l n o t o n l y t o man, b u t
t o a11 p l a n t s and a n i m a l s . The i n c r e a s e i n t h e e x t e n t t o which w a t e r i s used i n o u r advanced t e c h n o l o g i c a l alone, s o c i e t y suggests g r e a t p o t e n t i a l f o r a c c e l e r a t i n g water c r i s e s . I n t h e U.S.A. 9 i t i s e s t i m a t e d t h a t 1 x 10'' t, (300 x 10 U.S. g a l l o n s ) o f w a t e r a r e w i t h d r a w n y e a r l y from lakes,
r i v e r s and s t r e a m s ( r e f .
5).
Over 90% of t h i s w a t e r
i n d u s t r i a l p u r p o s e s and much of i t i s used and d i s c h a r g e d as w a s t e w a t e r .
i s used f o r This water
may be changed s i g n i f i c a n t l y and p o s s i b l y c r e a t e h e a l t h problems.
Characteristics of
water which are c i t e d i n w a t e r - q u a l i t y c r i t e r i a a r e d i s s o l v e d oxygen; floating
solids,
viruses;
taste;
scum, odor;
particulates);
color;
turbidity;
s a l t s ( i n c l u d i n g ammonia,
organic compounds; p e s t i c i d e s ; herbicides;
cations,
man-made
organic
materials;
anions);
protozoa,
pH;
and r a d i o a c t i v e m a t e r i a l s .
have adapted t o t h e n a t u r a l o r g a n i c m a t e r i a l s recent
s o l i d s (sludge,
bacteria,
however,
i n t h e water, man
has
Aquatic species
and even some o f
increased
his
fuels,
plastics,
detergents,
solvents,
Unless t h e r e i s a s p i l l ,
dyes,
inks,
paint,
drugs,
the
production of
organic wastes which e n t e r our water system as i n d u s t r i a l by-products o r waste,
herbicides.
and
temperature;
pesticides,
e.g. and
most o f these p o l l u t a n t s a r e present i n small
amounts (as f a r as economical r e c l a i m i n g i s concerned) and cause t o x i c problems t o man,
animals,
and f i s h .
Many o f
these products a r e n o t biodegradable
broken down by b a c t e r i a ) , and are passed on from f i s h t o animal and man.
( a b l e t o be O i l f i l m s on
water prevent the oxygen and carbon d i o x i d e exchange between a i r and water and i n t u r n k i l l many waterfowl and f i s h .
Water p o l l u t i o n and i t s many r e s u l t i n g problems c o u l d
be reduced by t h r e e main requirements:
( 1 ) A i l municipal sewage be given primary,
secondary and t e r t i a r y p u r i f i c a t i o n
treatments.
( 2 ) I n d u s t r i a l waste be reasonably c l e a r o f such t r a c e p o l l u t a n t s b e f o r e being passed i n t o our waterways.
( 3 ) I n d u s t r i a l p l a n t s consider t h e r e c y c l i n g o f water. Subsequent chapters i n t h i s book w i l i o u t l i n e t h e r o l e o f chromatography
for
t h e a n a l y s i s and i d e n t i f i c a t i o n o f some o f our environmental challenges.
1.2 METHODOLOGICAL OUESTIONS The e f f e c t s o f our e f f o r t s t o p r o t e c t t h e environment are d i r e c t l y p r o p o r t i o n a l t o our capabi I i t i e s o f measuring t h e l e v e l o f changes i n our environment. awareness o f environmental problems i s needed;
however,
Popular
t h e r e s p o n s i b i l i t y f o r estab-
l i s h i n g an accurate environmental baseline, f o r s e t t i n g and implementing standards and f o r m o n i t o r i n g environmental
change must r e s t w i t h t h e
r e s p o n s i b i l i t y i s awesome and must c a r r y w i t h careful
implementation o f
all
aspects o f
analytical
i t a deep moral
chemist.
commitment
environmental/anaiytical
This for
chemistry.
the The
a n a l y t i c a l chemist must consider every aspect o f samples i n t h e l i g h t o f t h e problem a t hand from s e l e c t i o n o f t h e sampling s i t e t o t h e f i n a l data i n t e r p r e t a t i o n . I n o r d e r t o measure any s p e c i e s o f d e s i r a b l e t o separate i t from a complex m a t r i x . t h e a n a l y t i c a l chemist a r e gas and/or
interest,
o f t e n i t i s n e c e s s a r y and
The most common separations t o o l s f o r
l i q u i d chromatography.
I t i s w i t h these t e c h -
niques t h a t t h i s book i s concerned.as they r e l a t e t o environmental
problem s o l v i n g .
For a comprehensive survey o f gas and l i q u i d chromatograhy, t h e reader should r e f e r t o
5 t h e books by Snyder (re
and K i r k l a n d
6 ) , Grob ( r e f . 7 ) and T o u c h s t o n e and Rogers
(ref.
. 8). The s e l e c t i o n o f
a separation
method
i s dictated
by t h e
b i I ty,
t h e number o f samples,
t h e r e q u i r e d a c c u r a c y and p r e c i s i o n ,
method,
t h e amount of sample p r e p a r a t i o n needed and t h e c o s t ,
order.
I f o n l y one t y p e o f i n s t r u m e n t i s a v a i l a b l e ,
instrument
no+ n e c e s s a r i l y i n +ha+
t h e o n l y p r o b l e m may be t o demon-
s t r a t e t h a t s e p a r a t i o n can be c a r r i e d o u t t o t h e d e s i r e d s p e c i f i c a t i o n . on t h e
accuracy,
experiment,
p r e c i s i o n and s e n s i t i v i t y o f
availa-
sensitivity o f the
+he method must
a l t h o u g h i t c a n o f t e n be p r e d i c t e d f r o m t h e
Information
be checked by
l i t e r a t u r e data.
The
s e n s i t i v i t y o f t e n r e 1 i e s on t h e c a p a b i l i t y o f t h e d e t e c t o r s ( s e e C h a p t e r s 5 and 6 ) . The sample p r e p a r a t i o n t i m e depends on t h e n a t u r e o f i n f o r m a t i o n needed.
t h e h i g h e s t budget i t e m . criteria,
Most
s t a n d a r d methods
i n v o l v e gas chromatography. t e c h n i q u e t o use t h a n
labor i s
I t i s o b v i o u s t h a t much c o n s i d e r a t i o n must be g i v e n t o t h e s e
and t h e p r o c e d u r e s o u t l i n e d w e l l
analysis.
+he p r o b l e m and t h e d e p t h o f
A f t e r t h e i n i t i a l purchase c o s t o f t h e instrumentation,
i n advance o f +he a c t u a l
chromatographic analyses of
for
I n general gas chromatography
1s a
laboratory
the
environment
less expensive
i s more f a m i l i a r t o most c h e m i s t s ,
l i q u i d chromatography,
and
has t h e advantage o f b e i n g c a p a b l e o f s e p a r a t i n g 20% o f t h e known o r g a n i c compounds w i t h o u t p r i o r m o d i f i c a t i o n o f t h e sample. more s e l e c t i v e t h a n advantage t h a t
Gas c h r o m a t o g r a p h i c d e t e c t o r s a r e g e n e r a l l y
I i q u i d chromatographic detectors.
i t can s e p a r a t e m i x t u r e s a t
and s t a t i o n a r y phase f o r i n c r e a s e d s e l e c t i v i t y , packings.
L i q u i d chromatography has t h e
lower t e m p e r a t u r e s ,
vary both t h e mobile
and can use a v a r i e t y o f u n i q u e column
The t w o t e c h n i q u e s a r e complementary and can be automated,
chromatography may p r e s e n t fewer
automation problems
bration,
gradient
liquid
concerned).
chromatographic
The n e x t seven c h a p t e r s
environmental problems using chromatography.
Tables 1.1
t o compare components o f
elution,
and 1.2 "clean
and
lay t h e foundation
t h e two popular
a l t h o u g h gas
( e s p e c i a l l y as f a r mobile for
phase
as e q u i l i -
disposal
are
+he c o m p l e t e a t t a c k on
a n a l y t i c a l techniques,
gas and l i q u i d
p r o v i d e +he b a s e l i n e i n f o r m a t i o n w h i c h o n e needs air
and w a t e r . "
Chapter 8 c o n t a i n s e x t e n s i v e
i n f o r m a t i o n on +he r e g u l a t i o n s by v a r i o u s g o v e r n m e n t a l a g e n c i e s .
6 TABLE 1.1 Composition of dry a i r a ( r e f . 9 ) Element
2
Concentration (%,v/v) 18.09 m.95 0.03 0.93
C6
Ar2
Element
2 He Ne
CH4
Concentration(ppm) ( ppm, v / v ) 0.5 1 5.2 18 2.2
aWater i s u s u a l l y present from 0.1 t o 3% I n t h e atmosphere. TABLE 1.2 Typical c a t i o n i c c o n c e n t r a t i o n r a t i o s ( r e l a t i v e t o potassium) i n sea and f r e s h water ( r e f . 10) Concentration(ppm) Cat ion Sea water Fresh water Sod i um Magnes 1 um Potass I um Calcium
50 5 1 1
2 1 1 5
REFERENCES I 2 3 4
5
6 7 8 9 10,
J. P. Lodge, Jr. i n J. N. P i t t s , Jr., R. L. M e t c a l f and D. Grosjean (Eds.), Advances I n Environmental Science and Technology, Wiley, New York, 1980. E. C. F u l l e r , Chemistry and Man's Environment, Houghton M l f f l i n Co., Boston, MA, 1974, p.2. D. H. Meadows, D. L. Meadows, J. Randers, and W. W. Behrens, The L i m i t s o f Growth, Universe Books, New York, 1972. R. G. Bond, C. P. Straub, and R. Prober (Eds.), CRC Handbook o f Environmental Control, Vol. 1: A i r P o l l u t i o n , CRC Press, Cleveland, OH, 1972, pp. 149-154. Anonymous, I n d u s t r i a l Wastewater, O f f i c e of Research and Development, United States Environmental P r o t e c t i o n Agency, C i n c i n n a t i , OH, 1980, p. 1. L. R. Snyder and J. J. K i r k l a n d , I n t r o d u c t i o n t o Modern L i q u i d Chromatography, Wlley, New York, 2nd ed., 1979. R. L. Grob (Ed.), Modern P r a c t i c e o f Gas Chromatography, Wiley, New York, 1977. J. C. Touchstone and D. Rogers (Eds.), Thin Layer Chromatography, Q u a n t i t a t i v e Environmental and C l i n i c a l A p p l i c a t i o n s , Wiley, New York, 1980. R. G. Bond, C. P. Straub, and R. Prober (Eds.), CRC Handbook of Environmental Control, Vol. 1 : A i r P o l l u t i o n , CRC Press, Cleveland, OH, 1972, p. 3. M. Waldrop. Chemical and Engineering News, American Chemical Society, Washington, DC,1980, p. 31.
CHAPTER 2 CRITERIA FOR THE SAMPLING PROCESS
2.1 REQUIREMENTS 2.1.1 General di scussion There is a time-honored saying that the analysis o f any sample can only be as good as the sample is representative. What this tells us very concisely is that it matters little how much technique we have accomplished or how expensive and elaborate are our laboratory instruments, the information obtained from the analysis will be meaningless if the sample does not represent the system from which it was obtained. It follows then that a corollary regarding sampling and analysis is that there i s little or no difference between a biologically-derived material and an industrially-derived material. The only difference from the analytical viewpoint is the number and amounts of the various components making up these materials. Regarding environmental samples, one may cite the overly simplified statement of Umbreit (ref. 1 ) to bring across this point: "Anything detected in a water sample which is not water must be considered a pollutant or contaminant. The same statement, of course, is true of air." Fortunately, we all know the problem is not quite that simple. Before sampling and/or analyzing an environmental sample the analytical chemist must perform some preliminary non-experimental work. Answers to some or all of the following should be known. (a) What chemical compounds are known or of concern in the sample? (b) A t what concentration levels do they exist? (c) What are the major components of the sample? (d) How much sample will be available? (e) Where and under what conditions will the sample be taken? (f) Can destructive or non-destructive anaiyses be used? (9) What conclusions and/or decisions are to be based on the analysis? There are a number of review articles which may be good starting points for background information on environmental analysis. A review article for potentially hazardous environmental substances determined by GC/MS was published by Oswald et al. (ref. Z ) , another for the analysis of organophosphorus insecticides and metabolites by Burchfield and Storrs (ref. 3 ) and a general review of pesticide residues by Thornburg (ref. 4). A state-of-the-art presentation appeared in the May, June and July 1975 issues of Journal of Chromatographic Science. Saltzman
8 and Cuddeback ( r e f .
5 ) and Fishman and Erdemann ( r e f . 6 ) have p u b l i s h e d r e v i e w s on
a i r p o l l u t i o n and o r g a n i c s discussed
various
for
analysis,
determination
respectively. of
trace
Weil
7)
has
water
and
(ref.
substances
in
Rosen ( r e f . 8 ) has d i s c u s s e d a g e n e r a l o u t l i n e f o r t h e i d e n t i f i c a t i o n o f
effluents. organic
i n water
methods
pollutants
in
water.
The
initial
separations
were
based
upon
group
s o l u b i l i t y and a d s o r p t i o n chromatography. Having
decided
on
a
chromatographic
technique,
a
knowledge
s e n s i t i v i t y l i m i t s t o be achieved w i t h t h e d e t e c t o r system i s assumed. samples and t h e degree o f c o n c e n t r a t i o n r e q u i r e d i s d e f i n e d . must be s e t ,
i.e.,
Sampling p r o c e d u r e s
t h e number o f samples and t h e method o f o b t a i n i n g t h e samples
o t h e r c o n s t i t u e n t s o f t h e sample, or
the
C o n c e n t r a t i n g t h e sought component, i s o l a t i o n o f i t f r o m a v a r i e t y o f
must be made. component
of
The s i z e o f
chemical
p a r t i a l i s o l a t i o n o r c o n c e n t r a t i o n o f t h e sought
conversion
to
a
derivative
of
different
chromatographic
b e h a v i o r ’ are now a l l p o s s i b l e s o l u t i o n s t o t h e a n a l y s i s problem. F i n a l l y , s t a n d a r d s must be p r e p a r e d t o e s t a b l i s h t h e t r u e minimum l e v e l o f d e t e c t i o n and t o c a l i b r a t e t h e response o f t h e system.
The f i n a l measurement s t e p
includes
temperature,
choice
of
chromatographic
column,
operating
m o b i l e phase
c o m p o s i t i o n and d e t e c t o r t y p e . The commonly disposal,
analytical
used
and t h e
particulates,
c h e m i s t s h o u l d have
analytical
techniques,
chemical
and p h y s i c a l
and aqueous s o l u t i o n s .
a
operation
thorough
knowledge o f
of
instrumentation
behavior
Finally,
the of
gaseous
systems,
t h e most at
his
airborne
he s h o u l d a s s u r e h i m s e l f t h a t h i s
sampling procedures and number o f samples w i l l p r o v i d e t h e b e s t r e s u l t s . The amount ( s i z e ) o f sample needed f r o m a system i s i n v e r s e l y r e l a t e d t o t h e s e n s i t i v i t y o f t h e a n a l y t i c a l t e c h n i q u e used. governed by t h e sampling system; m l / m i n o r m3/min.
Time r e q u i r e d f o r t h e s a m p l i n g i s
t h e system may be c a p a b l e o f a s a m p l i n g r a t e o f
E f f i c i e n c y o f t h e c o l l e c t i o n system i s t h e c o n t r o l l i n g f a c t o r -
an adequate and r e p r e s e n t a t i v e sample must be p r o v i d e d .
Sampling t i m e w i l l p r o v i d e A number o f f a c t o r s w i l l
an average c o n c e n t r a t i o n l e v e l f o r t h e i n t e r v a l covered. c o n t r o l t h e minimum sampling t i m e . range of t h e sought component,
These f a c t o r s i n c l u d e t h e e x p e c t e d c o n c e n t r a t i o n
t h e r a t e a t w h i c h t h e s a m p l i n g i s t o b e performed,
t h e minimum d e t e c t a b l e q u a n t i t y o f t h e sought component by t h e a n a l y t i c a l p r o c e d u r e used, at
and t h e i n t e r p r e t a t i o n o r use o f t h e f i n a l d a t a .
least
751
i s necessary f o r most
all
A collection efficiency o f
environmental
analyses
(ref.
9).
To
m a i n t a i n t h i s l e v e l o f e f f i c i e n c y i t i s sometimes n e c e s s a r y t o u s e s e v e r a l p i e c e s o f apparatus a n d / o r techniques.
I f t h i s proves t o be necessary,
t h a t t h e c o l l e c t i o n u n i t s do n o t i n t e r f e r e w i t h each o t h e r . a i r sample, i t i s a d v i s a b l e t o remove p a r t i c u l a t e m a t t e r f i r s t . using a f i l t e r
ahead o f
t h e gas-sampling
unit.
t h e n one must e n s u r e When g a s - s a m p l i n g an T h i s may be done b y
C a u t i o n i s a d v i s e d because o f
a d s o r p t i o n o f t h e gaseous components on t h e f i l t e r a n d / o r p a r t i c u l a t e s .
One can
9 d e t e r m i n e t h e e f f i c i e n c y o r e f f e c t i v e n e s s of t h e s a m p l i n g system b y use o f s y n t h e t i c e n v i r o n m e n t a l samples under c o n t r o l l e d l a b o r a t o r y c o n d i t i o n s and a w i d e r a n g e o f standard concentrations.
Inefficient
sample c o l l e c t i o n u s u a l l y b e g i n s t o appear as
lower and lower c o n c e n t r a t i o n s t a n d a r d s a r e used. One may check t h e e f f i c i e n c y
of
v a r i o u s i m p i n g e r s o r wash b o t t l e s (see
Chapter 3 ) by c o n n e c t i n g s e v e r a l o f them i n s e r i e s and p a s s i n g a gaseous sample o f known contaminant c o n c e n t r a t i o n t h r o u g h t h e system.
Each b o t t l e i s s u b s e q u e n t l y
analyzed and if t h e contaminant u p t a k e i s g r e a t e r t h a n 9 0 % i n t h e f i r s t b o t t l e , may b e c o n s i d e r e d e f f i c i e n t .
E f f i c i e n c y o f a i r sampling approaches 100%
sample i s c o l l e c t e d by passage i n t o an evacuated c o n t a i n e r .
it
if the
in t h i s type
However,
o f sampling, one must c o n s i d e r w a l l e f f e c t s o f t h e c o n t a i n e r . A f i n a l comment about a i r sampling - a i r a n a l y s i s i s o f no use i f t h e
sample i s c o l l e c t e d w h i l e i t i s r a i n i n g o r snowing.
The presence o f t h e l i q u i d
phase tends t o obscure a c c u r a t e d a t a f o r an a i r sample. snow) i s a major source of n u t r i e n t s .
Precipitation
(rain or
Concentrations o f i o n i c species i n t h e a i r
u s u a l l y f o l l o w a p a t t e r n a c c o r d i n g t o sampling area l o c a t i o n and t h e season ( r e f . 10).
The
rainwater
has
distinctive qualities
and t h e r e f o r e has
r e g i o n a l , n a t i o n a l and c o n t i n e n t a l w a t e r s u p p l i e s .
an
effect
on
Many o f t h e chemical s u b s t a n c e s
found i n streams can be a t t r i b u t e d t o man's e n v i r o n m e n t a l p o l l u t i o n a n d / o r c o n t r o l . 2.1.2
C r i t e r i a f o r sampling Sampling
from
either
s t r a i g h t f o r w a r d procedure. are
directly
air
or
water
systems
is
not
a
simple
and
The a n a l y t i c a l c h e m i s t must be c e r t a i n t h a t h i s samples
r e l a t e d t o t h e c o n t a m i n a n t c o n c e n t r a t i o n s and t h a t
s u b s t a n t i a t e t h e reasons f o r c o l l e c t i n g samples i n i t i a l l y .
h i s data w i l l
The f a c t t o keep i n m i n d
i s t h a t e n v i r o n m e n t a l contaminants e x h i b i t a v a r i a b l e c o n c e n t r a t i o n and t h u s a r e d e s c r i b e d by normal s t a t i s t i c s
(ref.
11).
An adequate s a m p l i n g p r o c e d u r e s h o u l d
answer a number o f q u e s t i o n s : (a) (b) (c) (d)
When does one s a m p l e ? Where does one sample ? For what t i m e p e r i o d does one s a m p l e ? How o f t e n a r e t h e samples t a k e n ?
Again, s t a t i s t i c s can a i d us i n o u r d e c i s i o n s ( r e f s . number o f samples, where t o sample, has been t h e f i n a n c i a l
etc.
12-18)
regarding the
However, i n many e n v i r o n m e n t a l s t u d i e s i t
l i m i t a t i o n s o f the p r o j e c t r a t h e r than experimental design
f r o m f i r s t p r i n c i p l e s which d i c t a t e d t h e answers t o t h e s a m p l i n g problem. I n t h e a n a l y s i s scheme o f e n v i r o n m e n t a l samples, o v e r which t h e c h e m i s t has some c o n t r o l . by t h e f o l l o w i n g s t a t e m e n t s ( r e f . 19).
i t i s t h e sampling step
Thus, t h e o v e r a l l scheme may b e sumned u p
10
program
.
( 1 ) S t a t i s t i c a l p r i n c i p l e s w i l l govern t h e adequacy o f t h e s a m p l i n g (2) P r o b a b i l i t y w i l l replace c e r t a i n t y i n the r e s u l t s . ( 3 ) S t a t i s t i c a l s i g n i f i c a n c e w i l l d e t e r m i n e t h e soundness o f t h e
conclusions.
2.1.3
Sample t y p e s and sampling p r o b l e m The a n a l y s i s o f e n v i r o n m e n t a l
samples p r e s e n t s t h e a n a l y t i c a l c h e m i s t a
d i v e r s i f i e d and c h a l l e n g i n g a r r a y o f sample t y p e s and sampling problems. systems t o be analyzed a r e homogeneous,
i n t h e sampling s t e p .
Under t h e s e c o n d i t i o n s , we would e n c o u n t e r l i q u i d s i n l i q u i d s gases i n gases ( u n i f o r m m i x i n g ) ,
gases i n l i q u i d s ( c o m p l e t e
and s o l i d s i n l i q u i d s ( c o m p l e t e s o l u b i l i t y ) .
The homogeneous system of
(complete m i s c i b i l i t y ) , solubility),
If the
t h e n l i t t l e o r no problems would be p r e s e n t
a s o l i d i n a s o l i d would be t h e l a s t t y p e o f sample i n t h i s c a t e g o r y .
This type
o f sample would be found most commonly i n p a r t i c u l a t e m a t t e r samples. The sample t y p e s which may cause s a m p l i n g problems would be t h e f o l l o w i n g : ( A ) A e r o s o l s a r e systems o f c o l l o i d a l p a r t i c l e s to 5 x 10-5 cm i n d i a m e t e r w h i c h w i l l n o t d i f f u s e t h r o u g h animal o r v e g e t a b l e membranes) d i s p e r s e d i n a gas, e.g., dusts, s o o t , p a r t i c l e s , fumes, smoke and f o g s . ( 6 ) Gels a r e systems v e r y analogous t o s o l s ( s e e F b e l o w ) formed by t h e c o a g u l a t i o n o f a c o l l o i d a l l i q u i d . ( C ) Foams a r e a d i s p e r s i o n o f a gas i n a l i q u i d . ( 0 ) Emulsions a r e c o l l o i d a l suspensions ( a system c o n s i s t i n g o f s m a l l p a r t i c l e s k e p t d i s p e r s e d by t h e m o l e c u l a r m o t i o n i n t h e s u r r o u n d i n g medium) o f l i q u i d s i n a l i q u i d . The l i q u i d phases a r e i m m i s c i b l e . (E) M i s t s a r e a suspension of a l i q u i d i n a gas, i . e . , a cloud-like aggregation o f minute globules o f water i n t h e atmosphere. ( F ) S o l s a r e a c o l l o i d a l suspension o f a s o l i d i n a l i q u i d . The problem-type chemist
as
electrical
they
samples all
a r e a cause f o r c a u t i o n on t h e p a r t o f
involve colloidal
particles.
charge i n many cases and have a v e r y
p r o p e r t i e s t e n d t o cause a d s o r p t i o n o f o t h e r
Colloidal
the analytical
particles
l a r g e surface area.
carry These
an two
components on t h e s u r f a c e and may
r e s u l t i n n o n - r e p r e s e n t a t i v e sampling and m i s l e a d i n g d a t a . The t e c h n i q u e s o f sampling a r e d i s c u s s e d i n d e t a i l i n Chapter 3; however, i t i s w e l l t o p o i n t o u t t h a t t h e s e t e c h n i q u e s may be m o d i f i e d because o f t h e system
b e i n g sampled. Time-Proportional
If t h e component o f most i n t e r e s t v a r i e s w i t h t h e t i m e o f day, Sampling i s performed.
T a k i n g samples o v e r
a prearranged time
p a t t e r n f u r n i s h e s more i n f o r m a t i o n t h a n one sample t a k e n f o r a l o n g p e r i o d o f t i m e .
I n t h e l a t t e r case one o b t a i n s
an average
level
component o f i n t e r e s t , whereas i n t h e f o r m e r case,
for
the concentration
of
the
a more r e a l i s t i c p a t t e r n o f t h e
11 fluctuation i n concentration results.
A s i m i l a r o c c u r r e n c e can p r e s e n t i t s e l f when
sampling w a t e r f r o m a f l o w i n g stream.
Because t h e f l o w r a t e may v a r y w i t h time,
it
i s b e t t e r t o t a k e samples based upon a p r e d e t e r m i n e d volume o r t o sample a t v a r i o u s t i m e s d u r i n g t h e d a y r a t h e r t h a n on a t i m e b a s i s . Flow-Proportional
Sampling.
This technique
i s called
T h i s method g i v e s s u p e r i o r i n f o r m a t i o n s i n c e t h e sample
t a k e n over a p e r i o d o f t i m e can f u r n i s h o n l y average c o n c e n t r a t i o n l e v e l s o f t h e component o f i n t e r e s t . it i s stated that a i r
I n S e c t i o n 2.1.1
analysis
samples a r e c o l l e c t e d d u r i n g a p e r i o d o f r a i n o r snow.
i s o f no use i f t h e
One c o u l d o b t a i n u s e f u l
i n f o r m a t i o n about t h e e f f e c t o f r a i n on a i r p o l l u t i o n b y s a m p l i n g t h e r a i n w a t e r . The c o m p o s i t i o n o f t h e r a i n w a t e r i s t o be c o n s i d e r e d when one i s i n t e r e s t e d i n t h e c o m p o s i t i o n o f s o i l and i r r i g a t i o n w a t e r s ( r e f . 20). rain
If
gauge.
the
rain
"cleared"
the
air
T h i s c o u l d b e done b y u s e o f a then
one
would
expect
large
R a i n w a t e r w i l l "wash"
c o n c e n t r a t i o n s o f many a i r p o l l u t a n t s i n t h e r a i n sample.
o u t and c o n c e n t r a t e many o r g a n i c ( i n c l u d i n g p e s t i c i d e s ) and i n o r g a n i c p o l l u t a n t s o f the a i r
(refs.
21-25).
The c l o s e r t o t h e ocean shores t h e r a i n w a t e r sample i s
taken the higher i s the s a l t content. R a i n gauges may be c l a s s i f i e d as a manual t y p e because t h e volume r e a d i n g In the automatic recording type,
must be checked p e r i o d i c a l l y , o r a u t o m a t i c t y p e . when
t h e compartment
i s full
of
r a i n water,
a switch
of
times
the
switch
is
tripped.
i s t r i p p e d and an empty
A r e c o r d i s k e p t f o r t h e number
compartment i s p o s i t i o n e d f o r f u r t h e r c o l l e c t i o n .
Knowing t h e c a l i b r a t e d volume
of
t h e gauge
compartment, one has t h e t o t a l volume o f r a i n c o l l e c t e d . A
laboratory
Urbana-Champaign,
has
Illinois,
been to
set
analyze
sampling s t a t i o n s i n t h e United States.
up
at
the
rain-water'
University
samples
from
of
Illinois,
fifty
nationwide
The l a b o r a t o r y i s p a r t o f t h e U n i t e d S t a t e s
N a t i o n a l Atmospheric D e p o s i t i o n Program ( r e f . 26).
The f i e l d samples may be checked
f o r a c i d i t y and c o n d u c t i v i t y a t t h e sampling s i t e .
A l l o t h e r analyses a r e performed
i n the laboratory a t the University o f I l l i n o i s . H u m i d i t y can a l s o a f f e c t a i r q u a l i t y .
Low h u m i d i t y r e s u l t s i n i n c r e a s e d
suspended p a r t i c u l a t e c o n c e n t r a t i o n s and h i g h h u m i d i t y ( f o g c o n d i t i o n s ) b l o c k s s o l a r heating
and
therefore
prolongs
the
life
of
inversion
layers
(ref.
t e m p e r a t u r e and f o g u s u a l l y cause i n c r e a s e d m o r b i d i t y and m o r t a l i t y ( r e f .
27).
Low
28).
Another i m p o r t a n t sample t y p e i s t h a t o b t a i n e d b y Stack Sampling ( r e f s . 29 and 30).
T h i s t y p e o f sampling i s performed e i t h e r t o m o n i t o r t h e e f f i c i e n c y o f an
i n d u s t r i a l c o l l e c t i o n system o r where a suspected o r known p o l l u t a n t has been f o u n d i n surrounding a i r .
J u s t i f i c a t i o n f o r e i t h e r o f t h e s e s i t u a t i o n s c o u l d be:
( 1 ) t o d e t e r m i n e whether a company i s i n c o m p l i a n c e w i t h l o c a l o r r e g i o n a l regulations;
( 2 ) t o e n a b l e a company t o s e l e c t a p p r o p r i a t e c o n t r o l equipment f o r i t s manufacturing sites; ( 3 ) t o i d e n t i f y t h e presence o f a p e r s i s t e n t c o n t a m i n a n t i n t h e s u r r o u n d i n g area; ( 4 ) t o d e t e r m i n e ifp r e s e n t c o n t r o l equipment needs t o b e changed o r improved; ( 5 ) t o m o n i t o r e m i s s i o n s when a m a n u f a c t u r i n g p r o c e s s has been changed; (6) f o r l e g a l reasons, e.g., t o s e t t l e a c o u r t s u i t o r t o answer a governmental r e g u l a t o r y agency c i t a t i o n . 2.2 PROBLEMS OF SAMPLING AND POST-SAMPLES T h i s s e c t i o n d i s c u s s e s s a m p l i n g i n g e n e r a l , w i t h c o n e n t s on problems and general precautions.
S p e c i f i c d i s c u s s i o n o f v a r i o u s t e c h n i q u e s w i l l be r e v i e w e d i n
Chapter 3. The m a j o r i t y o f e n v i r o n m e n t a l samples a r e e i t h e r l i q u i d s o r gases. w i t h these two sample t y p e s t h a t we a r e m a i n l y concerned.
It i s
Sampling t e c h n i q u e s used
f o r s u r f a c e waters, groundwaters, i r r i g a t i o n and d r a i n a g e w a t e r s a r e e s s e n t i a l l y t h e
A s i m i l a r s t a t e m e n t may be made o f a t m o s p h e r i c a i r samples,
same.
samples,
stack
associated
samples,
with
"post-sampling"
and
sampling
general
may
be
in-house
classified
laboratory a i r
samples.
Many
as
occurring
those
of
the
problems
during
the
period.
Environmental problems w o u l d b e v e r y s t r a i g h t f o r w a r d i f a l l samples were stable f o r
long periods o f time.
analyses a r e performed. the
sample
obtained
in
and
the
stored,
Stability of
samples s h o u l d be checked b e f o r e
Storage s t a b i l i t y can be a f f e c t e d b y t h e s t o r a g e c o n t a i n e r ,
container,
environmental
concentration
of
the
conditions
under
contaminants
of
which
interest,
a sample i s adsorption
e f f e c t s , and presence o f o t h e r chemical e n t i t i e s i n t h e sample. Depending upon t h e s o u r c e and t y p e o f refrigerate, (i.e.
analyze
immediately,
l e a v e no headspace),
use c o m p l e t e l y
o r add a b a c t e r i a l
d i s s o l v e d gases w i l l escape f r o m w a t e r samples periods before analysis.
I n general,
i t may be n e c e s s a r y t o
sample, filled
water
inhibitor.
sample
containers
V o l a t i l e m a t e r i a l s and
i f a l l o w e d t o be s t o r e d f o r
f i l l i n g o f t h e w a t e r sample c o n t a i n e r
long (no
headspace) and r e f r i g e r a t i o n w i l l m i n i m i z e these post-sampl i n g changes. Other p o s t - s a m p l i n g occur.
problems may a r i s e i f chemical
o r p h y s i c a l changes
I n t h i s i n s t a n c e , h a v i n g as much advance o r a d d i t i o n a l i n f o r m a t i o n r e g a r d i n g
t h e sample source m i n i m i z e s t h e s e problems. sample, nitrogen,
for
example,
hydrolysis
may cause of
urea
to
such
The presence o f b a c t e r i a i n a w a t e r
changes
ammonia,
as
reduction
oxidation
of
of
ammonia
urea to
to
gaseous
nitrite
and
n i t r a t e , and f o r m a t i o n o f v o l a t i l e f a t t y a c i d s ( r e f . 2 0 ) . L i g h t can a c c e l e r a t e many chemical r e a c t i o n s .
Thus,
i s e s s e n t i a l i f t h e samples cannot be analyzed i m m e d i a t e l y . o f environmental
gas
samples where
samples were s t o r e d i n d i r e c t s u n l i g h t .
photochemical
storage i n the dark
This i s especially t r u e
reactions could r e s u l t
if t h e
13 Another problem w i t h e n v i r o n m e n t a l samples which p r e v e n t s t h e p r e s e r v a t i o n of
integrity
of
the
sample
is
loss
the
occurring
during
separation
and/or
concentration steps.
Due t o t h e low c o n c e n t r a t i o n o f many c o n t a m i n a n t s i n a i r and
water
analytical
samples,
the
chemist
must
employ
c o n c e n t r a t i o n t e c h n i q u e p r i o r t o t h e measuring s t e p .
some
separation
and/or
Disregard f o r t h e possible
makeup o f t h e sample can f u r n i s h sample a n a l y s i s d a t a w h i c h i s meaningless. distillation
Steam
i s a handy t e c h n i q u e f o r removing and c o n c e n t r a t i n g v o l a t i l e s f r o m
water; whereas, e x t r a c t i o n i s a good t e c h n i q u e f o r a c c o m p l i s h i n g t h e same end r e s u l t for
neutral
or non-volatile
components.
The r e a d e r
i s r e f e r r e d t o a number o f
r e f e r e n c e s r e g a r d i n g sampling and c a r e o f w a t e r samples ( r e f s . 31-49). 2.3 REGULATIONS Specific
i n f o r m a t i o n r e g a r d i n g t h e v a r i o u s w o r l d w i d e r e g u l a t o r y agencies
i s d i s c u s s e d i n Chapter 8.
Our concern a t t h i s p o i n t i s more a g e n e r a l s t a t e m e n t
c o n c e r n i n g t h e r e g u l a t i o n s on sampling as a whole. Each of
the associations
and a g e n c i e s o f
the
i n d i v i d u a l c o u n t r i e s has
r e q u i r e m e n t s which a r e p e r t i n e n t t o t h e i r s p e c i f i c problems. f o r a l l t e c h n i q u e s o f sampling,
The u n d e r l y i n g reasons
t y p e s o f samples and t h e i r subsequent a n a l y s e s a r e
about t h e same. The r o l e o f t h e a n a l y t i c a l important.
chemist i s v i t a l f o r t h e be e f f e c t i v e , initially, samples, last
but
chemist
in all
o f these p r o j e c t s i s very
He i s necessary n o t o n l y f o r t h e a n a l y s i s p e r se,' he
must
but the analytical
If he i s t o
success o f r e s o l v i n g e n v i r o n m e n t a l problems. be
an
integral
part
o f .the
t h e d e s i g n o f t h e s a m p l i n g program,
discussion
of
the
problem
t h e g a t h e r i n g and c o d i n g o f t h e
t h e l a b e l i n g and c a r e o f t h e samples a t t h e c o m p l e t i o n o f t h e study, not
least,
the
interpretation
of
t h e data.
and
He must b e c a p a b l e o f
d i s c u s s i n g and e x p l a i n i n g t h e d e t a i l s and r e s u l t s o f such s t u d i e s t o p e r s o n s n o t w e l l versed i n t h i s area, e.g.,
other chemists, b i o l o g i s t s , p h y s i c i s t s ,
p h y s i c i a n s , t h e man on t h e s t r e e t , judges, j u r o r s , and p o l i t i c i a n s .
engineers,
Rightfully, the
a n a l y t i c a l c h e m i s t must become c o m p l e t e l y i n v o l v e d i n e n v i r o n m e n t a l problems and n o t f o l l o w t h e narrow p a t h o f a c c e p t i n g samples,
analyzing
t h e s e samples,
and t h e n
p a s s i n g t h e d a t a t o someone e l s e . Having e s t a b l i s h e d t h a t an e n v i r o n m e n t a l p r o b l e m e x i s t s ,
t h e n e x t move i s
t o l a y o u t t h e p r o j e c t so t h a t s u f f i c i e n t i n f o r m a t i o n becomes a v a i l a b l e t o a r r i v e a t t h e c o r r e c t conclusions. There a r e a number o f o r g a n i z a t i o n s
w h i c h have t h e r e s p o n s i b i l i t y
e i t h e r s e t t i n g o r c o n t r o l l i n g r e g u l a t i o n s p e r t a i n i n g t o environmental The a d m i n i s t r a t o r
o f t h e U n i t e d S t a t e s E n v i r o n m e n t a l P r o t e c t i o n Agency (EPA),
example,
sure
must be
the
agency p u t s
forth
criteria that
reflect
of
guidelines. the
for
latest
14 s c i e n t i f i c knowledge u s e f u l
i n i n d i c a t i n g t h e e f f e c t s on p u b l i c h e a l t h o r w e l f a r e
expected f r o m p o l l u t a n t s i n ambient a i r and i n d u s t r i a l waste w a t e r e f f l u e n t s .
The
criteria
are
with
which
p a r t i c u l a t e matter,
they
have
been
s u l f u r oxides,
polychlorinated biphenyls
concerned
mainly
carbon monoxide,
(for
air
pollution)
n i t r o g e n oxides,
(PCBs) and o t h e r h a l o g e n a t e d o r g a n i c s ,
hydrocarbons,
and photochemical
oxidants.
For w a t e r p o l l u t i o n t h e y have been concerned p r i m a r i l y w i t h p e s t i c i d e s ,
herbicides,
p o l y c h l o r i n a t e d b i p h e n y l s and o t h e r h a l o g e n a t e d o r g a n i c s ,
toxic trace
A l l o f t h e s e p o l l u t a n t s and methods f o r t h e i r
m e t a l s and v a r i o u s i n d u s t r i a l wastes.
d e t e r m i n a t i o n a r e c o n s t a n t l y b e i n g reviewed. The Committee on t h e Challenges o f Modern S o c i e t y (CCMS) e s t a b l i s h e d b y t h e N o r t h A t l a n t i c T r e a t y O r g a n i z a t i o n (NATO) s e t up s e v e r a l a i r p o l l u t i o n s t u d i e s . Procedures p u b l i s h e d by t h i s commission d i f f e r f r o m c r i t e r i a s e t by t h e U.S.A
(ref.
50). The
National
Research
Counci 1 / N a t i o n a l
Academy
of
Sciences
(NRC/NAS)
p u b l i s h e d a number o f documents r e v i e w i n g i n f o r m a t i o n about many s p e c i f i c substances ( r e f . 51).
These were f o l l o w e d b y documents o u t l i n i n g a p h i l o s o p h y f o r s h o r t - t e r m
a i r q u a l i t y l i m i t s ( r e f . 52). The World H e a l t h O r g a n i z a t i o n (WHO) e s t a b l i s h e d a c o m n i t t e e on A i r Q u a l i t y C r i t e r i a and Guides and p u b l i s h e d a r e p o r t e n t i t l e d A i r Q u a l i t y C r i t e r i a and Guides for
Urban P o l l u t a n t s
(ref.
53).
The
p r e s e n t WHO
Environmental Health C r i t e r i a
Programme ( r e f . 54) was a r e s u l t o f t h e i n i t i a l s t u d y . The U n i t e d N a t i o n s Conference on t h e Human Environment charged WHO w i t h t h e t a s k o f e s t a b l i s h i n g p r i m a r y s t a n d a r d s f o r p o l l u t a n t s t h a t a r e common t o a i r , water,
and food,
common a i r
and d e v e l o p i n g procedures f o r s e t t i n g d e r i v e d w o r k i n g l i m i t s f o r
and w a t e r contaminants.
"Derived working l e v e l s "
a r e a l s o known as
e n v i r o n m e n t a l o r ambient a i r qua1 i t y s t a n d a r d s , maximum p e r m i s s i b l e l i m i t s , maximum a l l o w a b l e c o n c e n t r a t i o n s o r p r o d u c t standards.
Air
and w a t e r p o l l u t i o n abatement
are d i f f e r e n t for
w i t h i n a c o u n t r y f r o m one l o c a t i o n o r t i m e p e r i o d t o another.
e v e r y c o u n t r y and
I f the major health
problems a r i s e f r o m an inadequate c l e a n w a t e r s u p p l y o r o t h e r s a n i t a t i o n problems, less
emphasis
c a n be
given
to
air
pollution
problems.
Conversely,
a
highly
i n d u s t r i a l i z e d c o u n t r y may s u f f e r g r e a t e r a i r p o l l u t i o n exposure problems t h a n w a t e r p o l l u t i o n problems p r o v i d e d waste dumping i n streams were c o n t r o l l e d . 2.4 STANDARDS 2.4.1
Discussion Verifications
samples.
The
standard
of
a n a l y t i c a l procedures
samples
are
used
to
presuppose
check
the
t h e use o f s t a n d a r d
correct
functioning
of
15
analytical
i n s t r u m e n t a t i o n and procedures.
aware of
sources
of
such samples,
the
Thus t h e a n a l y t i c a l c h e m i s t s h o u l d b e c o o p e r a t i v e programs
which
govern
these
v e r i f i c a t i o n samples, and t h e t y p e s o f samples and s u p p l i e s a t h i s d i s p o s a l . Commercial
and
governmental
agencies
are
the
The EPA p u b l i s h e s A i r P o l l u t i o n A b s t r a c t s m o n t h l y ( r e f . concerned w i t h source sampling and analyses (ref.
main
sources
of
such
A number o f p u b l i c a t i o n s a b s t r a c t t h e e n v i r o n m e n t a l l i t e r a t u r e ( r e f . 5 5 ) .
samples.
58),
evaluation
and
detection
of
(ref.
5 6 ) and a number o f books
57),
aerosols
monitoring a i r pollutants (ref.
59)
and
monitoring
i n s t r u m e n t a t i o n and sampling d e s c r i p t i o n s ( r e f s . 60 and 6 1 ) a r e a l s o a v a i l a b l e . Air
and
water
concentration o f water volume.
quality
standards
are
legal
limits
placed
on
the
and a i r p o l l u t a n t s f o r a g i v e n p e r i o d o f t i m e o r a g i v e n
These c r i t e r i a a r e d e c i d e d by c o n s i d e r a t i o n o f economic, s o c i a l ,
technical
and p o l it i c a l i n f o r m a t i o n . The a v a i l a b i l i t y o f a i r and w a t e r s t a n d a r d s does n o t p r e c l u d e t h e removal o f interferences.
A number o f common a n a l y t i c a l t e c h n i q u e s a r e used f o r t h e removal
o f i n t e r f e r i n g substances.
These s h o u l d be c a l l e d upon t o a s s i s t i n many a n a l y s e s .
Some o f t h e more r o u t i n e l y used approaches t o removal o f i n t e r f e r e n c e s a r e : ( 1 ) change i n t e m p e r a t u r e o f t h e sample system; ( 2 ) ashing o f residues obtained e i t h e r from separation o f groups o f compounds o r s p e c i f i c substances; ( 3 ) use o f i o n exchange t o remove i o n i c i n t e r f e r e n c e s ; ( 4 ) d i s t i l l a t i o n t o remove low b o i l i n g components; ( 5 ) c o m p l e x i n g agents t o mask an i n o r g a n i c i n t e r f e r e n c e ; ( 6 ) change i n pH o f sample system; ( 7 ) use o f r e a c t i o n k i n e t i c s t o a l t e r amount o f i n t e r f e r i n g substances. I n t e r f e r e n c e s can o c c u r d u r i n g v a r i o u s s t e p s i n t h e process o f o b t a i n i n g t h e d e s i r e d analytical information. themselves,
The more common sources would be ( a ) a t t h e s a m p l i n g s i t e s
( b ) sample c o l l e c t i o n system c o u l d be t h e problem,
may t a k e p l a c e d u r i n g t h e sample s t o r a g e i n t e r i m , during the analysis.
These i n t e r f e r e n c e s may n o t be s o l e l y chemical,
p h y s i c a l i n n a t u r e , e.g., photo-oxidation),
( c ) r e a c t i o n which
and ( d ) p o o r l a b o r a t o r y t e c h n i q u e
temperature e f f e c t s ,
b u t may be
l i g h t e f f e c t s (photo-decomposition o r
t i m e i n t e r v a l between s a m p l i n g s t e p and a n a l y s i s s t e p , o r u n c l e a n
equipment. Control
o f sampling parameters and a n a l y s i s p r o c e d u r e s w i l l s t i l l produce
indeterminate e r r o r s i n the data.
These may be h a n d l e d i n a s t a t i s t i c a l manner.
The scope o f t h i s t r e a t i s e does n o t p e r m i t t h e coverage o f t h i s t o p i c . i s r e f e r r e d t o a number o f i : i s t r u c t i v e r e f e r e n c e s ( r e f s . 12-18).
The r e a d e r
16 2.4.2
A v a i l a b i l i t y and source o f samples and s u p p l i e s T a b l e 2.1 i s a l i s t i n g o f v a r i o u s s u p p l i e r s o f e n v i r o n m e n t a l s t a n d a r d s f o r
gas and l i q u i d chromatography.
Also included a r e those s u p p l i e r s which f u r n i s h
column s u p p l i e s and r e f e r e n c e samples.
T h i s i s n o t an a l l - i n c l u s i v e
a l i s t o f sources known a n d / o r used b y t h e a u t h o r s .
listing, but i s
T h i s l i s t i n g i s n o t t o be
i n t e r p r e t e d as an a p p r o v a l o r recommendation by t h e a u t h o r s .
TABLE 2.1 S u p p l i e r s o f e n v i r o n m e n t a l samples, standards, and s u p p l i e s Supplier
Product type ( s ) *
A i r c o I n d u s t r i a l Gases 575 Mountain Avenue, M u r r a y H i l l , NJ 07974, USA.
CRM, RM
A i r P r o d u c t s and Chemicals, I n c . S p e c i a l t y Gas Department P.O. Box 538, A l l e n t o w n , PA 18105, USA.
CRM, RM, Gas standards, Std. gas samples
A l d r i c h Chemical Co., I n c . 940 W. S t . Paul Avenue, Milwaukee, W I 53233, USA.
GC and LC s t a n d a r d s
Aldrich-Europe, D i v i s i o n o f Janssen P h a r m a c e u t i c a l s Turnhoutsebaan-30, 62340, Beerse, Belgium.
GC and LC s t a n d a r d s
Alpha A n a l y t i c a l L a b o r a t o r i e s D i v i s i o n o f Alpha Metals, I n c . 56 Water S t r e e t J e r s e y City, NJ 07304, USA.
CRM, RM
A1 1t e c h A s s o c i a t e s 2051 Waukegan Road D e e r f i e l d , I L 60015, USA.
GC standards, GC and LC pack ings
American Petroleum I n s t i t u t e Standard Reference M a t e r i a l s Carnegie-Mellon U n i v e r s i t y Schenley Park, P i t t s b u r g h , PA 15213, USA.
CRM, RM
Analabs, I n c . (Foxboro A n a l y t i c a l ) 80 R e p u b l i c D r i v e N o r t h Haven, CT 06473, USA.
GC standards, GC and LC packings
A p p l i e d Science L a b o r a t o r i e s , I n c . P.O. Box 440 S t a t e College, PA 16801, USA.
GC standards, GC and LC packings, RM
17 A p p l i e d Science Europe B. V. P.O. Box 1149, 3260 A C OudBeij e r l a n d , The N e t h e r l a n d s .
GC standards, GC and LC packings, RM
Arro Laboratories, Inc. P.O. Box 686, Caton Farm Road, J o l i e t , I L 60434, USA.
CRM, RM
Association o f O f f i c i a l Analytical Chemists, Box 540, Benjamin F r a n k l i n S t a t i o n Washington, DC 20040, USA.
GC and LC s t a n d a r d s
Bai r d C o r p o r a t i o n 125 M i d d l e s e x T u r n p i k e Bedford, MA 01730, USA.
CRM
Baird-Atomic L t d . Warner D r i v e , Springwood I n d . E s t a t e , Rayne Road, B r a i n t r e e , Essex, Great B r i t a i n
CRM
J. T. Baker Chemical Company 222 Red School Lane P h i l l i p s b u r g , NJ 08865, USA
CRM, RM, GC s t a n d a r d s , GC and LC p a c k i n g s
Baker-Chemi k a l i e n , P o s t f a c h 1661, Gross-Geran German F e d e r a l R e p u b l i c
CRM, RM, GC s t a n d a r d s , GC and LC p a c k i n g s
BDH Chemicals, L t d . Poole, D o r s e t BH12 4NN, Great B r i t a i n
GC s t a n d a r d s
Bramner Standard CO, 213-Essex K n o l l D r i v e C o r a o p o l i s , PA 19108, USA
CRM, RM
Brinkman I n s t r u m e n t s , I n c . Cantiague Road Westbury, NY 11590, USA
RM
B u r d i c k and Jackson L a b o r a t o r i e s 1953 South Harvey S t r e e t Muskegon, M I 49442, USA
RM, GC and LC s t a n d a r d s
Bureau of A n a l y t i c a l Samples, L t d . Newham H a l l , Newly, M i d d l e b o r o u g h TS8 9EA, Great B r i t a i n
GC and LC s t a n d a r d s
C a l i f o r n i a Bionuclear Corporation 7654 San Fernando Road Sun V a l l e y , CA 91352, USA
CRM
C a r l o Erba Strumentazione SpA P.O. BOX 4342, 1-20100 Milan, I t a l y
GC s t a n d a r d s and p a c k i n g s
18
Chem. S e r v i c e . I n c . P. 0. Box 194 West Chester, PA 19380, USA.
GC and LC s t a n d a r d s
Chrompack Nederland BV P. 0. Box 3, 4-330 AA M i d d l e b u r o The Netherlands,4330
GC s t a n d a r d s , GC and LC pack ings
Coast Engi neer ing Lab 13508 S. Normandie Avenue Gardena, CA 90249, USA.
GC s u p p o r t s
P. J. Cobert Associates, I n c . 10767 I n d i a n Head I n d u s t r i a l D r i v e S t . Louis, MO 63132, USA.
GC and LC p a c k i n g s
Columbia S c i e n t i f i c I n d u s t r i e s 11950 J o l l y v i l l e Road P.O. Box 9908, A u s t i n , TX 78766, USA.
CRM, RM
C. Desaga GmbH, Nachf. E r i c h F e c h t Maasstrasse 26-28, P.O. Box 101969, D-6900 H e i d e l b e r g 1 German F e d e r a l R e p u b l i c
GC s t a n d a r d s
Duke Sc i e n t i f ic C o r p o r a t ion 445 Sherman Avenue, P a l o A l t o , CA 94306, USA
CRM, RM
E. I . du Pont de Nemours and Co. Analyical Instruments D i v i s i o n Room 38830 Wilmington, DE 19898, USA
LC p a c k i n g s
Du Pont U.K, L t d . Ana 1 y t ic a 1 I n s t r u m e n t s Wedgewood Way, Steuenage H e r t s , SGI 4QN, Great B r i t a i n
LC packings
E. I . du Pont de Nemours (Deutschland) GmbH 'nstrument P r o d u c t s D i v i s i o n J i e s e l s t r a s s e 18, P.O. Box 1509, 06350 Bad Neuheimel, German F e d e r a l R e p u b l i c
LC p a c k i n g s
Eas tman Kodak Company Eastman Organic Chemicals Rochester, NY 14650, USA
CRM, RM
EM L a b o r a t o r i e s , I n c . 500 E x e c u t i v e B o u l e v a r d Elmsford. NY 10523, USA
RM
Environmental P r o t e c t i o n Agency Qua1 i t y Assurance Branch Environmental M o n i t o r i n g and Support Laboratory C i n c i n n a t i , OH 45268, USA
QC s t a n d a r d s
19 Environmental Resource A s s o c i a t e s Department A 120 E a s t Sauk T r a i l South Chicago H e i g h t s , I L 60411. USA.
Environmental r e f e r e n c e samples, p o t a b l e w a t e r r e f e r e n c e samples, p e s t i c i d e r e f e r e n c e samples
ES I n d u s t r i e s 8 South Maple Avenue M a r l t o n , NJ 08053, USA.
LC p a c k i n g s
Foxboro A n a l y t i c a l , see Analabs, I n c . Foxboro Nederland N.V. Analytical Division S. Gravelandseweg 557, P.O. Schiedam, The N e t h e r l a n d s .
GC standards, GC and LC packings Box 113
Hopkins and W i l l i a m s P.O. Box 1, Romford, Essex R M l lHA, Great B r i t a i n .
GC and LC p a c k i n g s
Hewlett-Packard Company 150 Page M i l l Road P a l o A l t o , CA 94304, USA.
GC p a c k i n g s , f u s e d s i l i c a OTC
I C N L i f e Sciences Group 26201 M i l e s Road Cleveland, OH 44128, USA.
CRM, RM
Jarrel-Ash(Div. o f Fisher S c i e n t i f i c Co.) Spectrographic Supplies Section 590 L i n c o l n S t r e e t , Route 128 Waltham, MA 02154, USA.
CRM, RM, GC standards, GC and LC p a c k i n g s
JASCO, I n c . 218 Bay S t r e e t , Easton, MD 21601, USA.
LC p a c k i n g s
Johns Manvi 1 l e Ken-Caryl Ranch, Denver, CO 80217, USA.
GC and LC p a c k i n g s
L.C. Company, I n c . 619 Estes Avenue Schaumberg, I L 60139, USA.
GC s t a n d a r d s , GC and LC pack ings
Leco C o r p o r a t i o n 3000 Lakeview Avenue, S t . Joseph, M I 49085, USA.
CRM, RM
Macherey-Nagel and Company, GmbH, E x p o r t , Werkstrasse 6-8, P.O. Box 307 D-5160 Duren, G.F.R.
GC and LC p a c k i n g s
Matheson Company P.O. Box E L y n d h u r s t , NJ 07071, USA.
GC s t a n d a r d s , GC and LC pack i n g s
20 Matheson Company N i j v e r h e i d s t r a a t 238, 8-2431 O l e v e l , Belgium
GC s t a n d a r d s , GC and LC pack ings
Nanogens-Analytical S p e c i a l i s t s P.O. Box 1025, W a t s o n v i l l e , CA 95076, USA.
RM
Packard-Becker BV P.O. Box 519, Vulcanusweg 259 26244 AV, D e l f t , The N e t h e r l a n d s .
GC p a c k i n g s
Packard I n s t r u m e n t Company 2200 W a r r e n v i l l e Road Downers Grove, I L 60515, USA.
GC p a c k i n g s
N.V. Packard I n s t r u m e n t S.A. L a k e n s t r a a t 168 6-1000, B r u s s e l s , Belgium.
GC p a c k i n g s
P e r k i n ' lmer C o r p o r a t i o n Main A$nue, Norwalk, CT 06851, USA. ,
GC and LC p a c k i n g s
Phase S e p a r a t i o n s L t d . Deeside I n d u s t r i a l E s t a t e Queenferry, F l i n t s h i r e , Great B r i t a i n .
GC and LC p a c k i n g s
Phase S e p a r a t i o n s Ltd., 255 Oser Avenue, Hauppauge, NY 11787, USA.
GC and LC p a c k i n g s
P h i l l i p s Petroleum Co. S p e c i a l Products D i v i s i o n B a r t l e s v i l l e , OK 74004, USA.
CRM,
P i e r c e Chemical Company P. 0. Box 117, Rockford, I L 61105, USA.
GC and LC p a c k i n g , s t a n d a r d s
P i e r c e Eurochemie, B.V. Box 1151, Rotterdam, The Netherlands
GC and LC p a c k i n g s , s t a n d a r d s
Polyscience Corporation 6366 Gross P o i n t Road N i l e s , I L 60648, USA.
CRM, RM, GC s t a n d a r d s
Pye Unicam, L t d . York S t r e e t , Cambridge CBI ZPX, Great B r i t a i n
GC and LC p a c k i n g s
Regis Chemical Company 8210 N. A u s t i n Avenue Morton Grove, I L 60053, USA.
GC s t a n d a r d s
RM
21 Research Organic/ Inorganic Chemical Corp. 11686 Sheldon S t r e e t Sun Valley, CA 91352, USA.
CRM, RM
S c i e n t i f i c Gas Products, Inc. 513 R a r i t a n Center, Edison, NJ 08817, USA.
CRM
The Separations Group P.O. Box 867, 16640 Spruce Street, Hesperia, CA 92345, USA.
LC packings
Shimadzu Corporation, L t d . i n t e r n a t i o n a l Manufacturing Div. 14-5 Uchikanda 1-chome, Chryoda-kui, Tokyo 101, Japan
GC packings
S c o t t S p e c i a l t y Gases S c o t t Environmental Technology,lnc, P l u m s t e a d v i l l e , PA 18949, USA.
CRM, RM, Cross r e f e r e n c e s e r v i c e c o l l a b o r a t i v e gas anal y s i s
Supelco, Inc. Supelco Park, P. 0. Box 581 B e l l e f o n t e , PA 16823, USA.
GC and LC standards, GC and LC packings, RM
Supelco S.A. European Rte De C l i g n y 3,1299 Crans. Switzerland
GC and LC standards, GC and LC packings, RM
Theta Corporation, Chemical D i v i s i o n , P.O. Box 167, Media, PA 19063, USA.
GC standards
U n i t e d States Geological Survey Water Resources D i v i s i o n U.S. Department o f I n t e r i o r Washington, DC, 20234, USA.
Ampoule water concentrates, prepared n a t u r a l water standards
Union Carbide Corporation, Linde D i v i s i o n , P.O. Box 372 51 Cragwood Road, South P l a i n f i e l d , NJ 07080, USA.
RM
U.S. Department of Commerce O f f i c e o f Standard Reference M a t e r i a l s , Washington, DC 20234 USA.
CRM, RM, Trace elements i n N a t i o n a l Bureau o f Standards water, gases f o r heavy duty v e h i c l e emissions a n a l y s i s
U.S. Department of I n t e r i o r Bureau o f Mines, Branch o f Engineering, Box H, 4372, H e r r i n g Plaza, A m a r i l l o , TX 79101, USA.
CRM, RM
LL
Universal S c i e n t i f i c , Inc. P. 0. Box 80402, 2070 Peachtree I n d u s t r i a l Court, A t l a n t a , GA 30341, USA.
GC s t a n d a r d s and packings, LC p a c k i n g s
Var i a n Associates 611 Hansen Way P a l o A l t o , CA 94303, USA.
GC s t a n d a r d s and p a c k i n g s , LC p a c k i n g s
Varian MAT CmbH Barkhausenstrasse 2, P o s t f a c h 1440 62, 2800 Bremen 12, G.F.R.
GC s t a n d a r d s and packings, LC p a c k i n g s
V-Tech C o r p o r a t i o n 16229 W. Ryerson Road, P.O. New B e r l i n , W I 53151, USA.
GC s t a n d a r d s
Box 183,
Waters Associates, I n c . 34 Maple S t r e e t , M i l f o r d , MA 01757, USA.
LC p a c k i n g s
Whatman, I n c . 9 B i r d e w e l l Place, C l i f t o n , NJ 07014, USA.
LC p a c k i n g s
Whatman L t d . S p r i n g f i e l d M i l l , Maidstone, Kent ME14 2LE, Great B r i t a i n
LC p a c k i n g s
*CRM = C e r t i f i e d r e f e r e n c e m a t e r i a l s ; RM
=
General r e f e r e n c e m a t e r i a l s .
REFERENCES 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
G. R. h b r e i t , Trace A n a l y s i s b y Gas Chromatography, i n R.L. Grob (Ed.), Modern P r a c t i c e o f Gas Chromatography, W i l e y - I n t e r s c i e n c e , New York 1977, p. 368. E. 0. Oswald, P. W. A l b r o and J.D. McKinney, J. Chromatog., 98, (1974), 363. H. P. B u r c h f i e l d and E. E. S t o r r s , J. Chromatog. Sci., 13 (1975), 202. W. Thornburg, Anal. Chem., 47 (1975) 157R. B. F. Saltzman and J. E. Cuddeback, Anal. Chem., 47 (1975), 1R. M. J. Fishman and D. E. Erdemann, Anal. Chem., 47 (1975) 334R. L. Wei 1, Muenchner Bei tr. Abwasser-Fisch-Flussbiol., 19, (1971 ) 191-200, C.A., 76 (1972) 3 7 1 3 7 ~ . A. A. Rosen, Symp. Org. M a t t e r N a t u r . Waters, 1968, pp. 359-367; C.A. 74, (1971), 6743r. P. M. Giever, P a r t i c u l a t e M a t t e r Sampling and S i z i n g , i n A.C. S t e r n (Ed.), A i r P o l l u t i o n , Academic Press, New York, 1976, p.6. W. H. Durum, C h a r a c t e r i s t i c s o f Water Resources, i n L. L. C i a c c i o (Ed.), Water and Water P o l l u t i o n Handbook, Vol. 1, Marcel Dekker, New York, 1971, Ch. 1. R. I . Larsen, C. W. Zimner, D. A. Lynn and K. G . Blemel, 3. A i r P o l l u t , C o n t r . Ass., 17, (1967) 85. W. J. Youden, S t a t i s t i c a l Methods f o r Chemists, Wiley, New York, 1951. American S o c i e t y f o r T e s t i n g M a t e r i a l s , ASTM Manual on Q u a l i t y C o n t r o l of M a t e r i a l s , Special T e c h n i c a l P u b l i c a t i o n , 15-C, ASTM, P h i l a d e l p h i a , PA, 1951. E. L. Bauer, A S t a t i s t i c a l Manual f o r Chemists, 2nd ed., Academic Press, New York, 1971. 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 , Proposed p r o c e d u r e f o r d e t e r m i n a t i o n o f p r e c i s i o n o f committee D-19 methods, i n Manual o n I n d u s t r i a l Water and I n d u s t r i a l Waste Water, 2nd ed., ASTM, P h i l a d e l p h i a , PA, 1966.
23 16 J . D. Hinchen, P r a c t i c a l S t a t i s t i c s f o r Chemical Research, Methuen and Co., London, 1969. 17 A. J. Duncan, Q u a l i t y C o n t r o l and I n d u s t r i a l S t a t i s t i c s , 3 r d ed., R. D. Irwin, Homewood, I L , 1965. 18 D. J. Cowden, S t a t i s t i c a l Methods i n Q u a l i t y C o n t r o l , P r e n t i c e - H a l l , Englewood C l i f f s , NJ, 1957. 19 A. L. L i n c h , E v a l u a t i o n o f Ambient A i r Q u a l i t y b y Personnel M o n i t o r i n g , CRC Press, Cleveland, OH, 1974, p.213. 20 J. D. Rhoades and L. B e r n s t e i n , Chemical, P h y s i c a l and B i o l o g i c a l C h a r a c t e r i s t i c s o f I r r i g a t i o n and S o i l Water, i n L. L. C i a c c i o (Ed.), Water and Water P o l l u t i o n Handbook, Vol. 1, Marcel Dekker, New York, 1971, Ch. 3. 21 D. C a r r o l l . U. S. Geol. Surv. Water-Supply Paper. 15356, U.S. Dept. I n t e r i o r , . Washington, DC 1962. 22 F. A. Herman and E. Gorham. T e l l u s . 9 (1957) 180. 23 G. H. Neumann, 5. F o r s e l i u s and L.’Wahiman,’Intern. J. A i r P o l l u t i o n , 2 (1959) 132. 24 G. A. Wheatley and J . A. Hardman, Nature, 207 (1965) 486. 25 S. R. Weibel, R. B. Weidner, A. G. C h r i s t i a n s o n and R. J. Anderson, Advances i n Water P o l l u t i o n Research, Water P o l l u t i o n C o n t r o l F e d e r a t i o n , Washington, DC, 1967, pp 329-342. 26 Anonymous, Chem. Eng. News, Feb. 5 (1979) 17. 27 American I n d u s t r i a l Hygiene A s s o c i a t i o n , A i r P o l l u t i o n Manual, P a r t I , E v a l u a t i o n , 2nd ed., D e t r o i t , M I , 1972. 28 M. W. F i r s t , E n v i r o n . Res., 2 ( 2 ) (1969) 88-92. 29 H. J. Paulus and R. W. Thron, Stack Sampling, i n A. C. S t e r n (Ed.), A i r P o l l u t i o n , Vol. 111, 1976, pp 525-587. 30 J. S. Nader, Source M o n i t o r i n g i n A. C. S t e r n (Ed.), pp 589-601. 31 H.B.N. Hvnes. The B i o l o q_-v o f P o l l u t e d Waters. L i v e r p o o l U n i v e r s i t y Press, L i v e r p o o i , 1960. 32 L . K l e i n ( E d . ) R i v e r P o l l u t i o n , 11, Causes and E f f e c t s , B u t t e r w o r t h s , London, 1962. 33 K. M. Mackenthum and W. M. Ingram, B i o l o g i c a l A s s o c i a t e d Problems i n Freshwater Environments - T h e i r I d e n t i f i c a t i o n , I n v e s t i g a t i o n and C o n t r o l , F e d e r a l Water P o l l u t i o n C o n t r o l Admin., Washington, DC,1967. 34 C. N. Sawyer and P. L. McCarty, Chemistry f o r S a n i t a r y Engineers, 2nd ed., McGraw-Hill, New York, 1967. 35 L . E. Keup, W. M. Ingram and K. M. Mackenthum, B i o l o g y o f Water Pa l u t i o n : A C o l l e c t i o n o f S e l e c t e d Papers on Stream P o l l u t i o n , Waste Water and Water Treatment, Publ. No. CWA-3, Federal Water P o l l u t i o n C o n t r o l Admin. Washington, DC ,1967. 36 P. S. Welch, Limnology, 2nd ed., McGraw-Hill, New York, 1952. 37 G. E. Hutchinson, A T r e a t i s e o n Limnology, V o l . 1, Geography, Phys cs, and Chemistry, W i l e y , New York,1957. 38 G. E. Hutchinson, A T r e a t i s e on Limnology, Vol. 2, I n t r o d u c t i o n t o Lake B i o l o g y and t h e Limnoplankton, Wiley, New York, 1967. 39 F. R u t t n e r , Fundamentals o f - L i m n o l o g y ( t r a n s l . b y D. G. F r e y and F. E. J. F r y ) , U n i v e r s i t y o f T o r o n t o Press, T o r o n t o , 1953. 40 G. K. Reid, Ecology o f I n l a n d Waters and E s t u a r i e s , R e i n h o l d , New York, 1961. 41 Standard Methods f o r t h e Examination o f Water and Wastewater, 1 2 t h ed., American P u b l i c H e a l t h A s s o c i a t i o n , New York, 1965. 42 P. S. Welch, L i m n o l o g i c a l Methods, B l a k i s t o n , P h i l a d e l p h i a , PA 1948. 43 H. A. P a i n t e r , Chemical, P h y s i c a l and B i o l o g i c a l C h a r a c t e r i s t i c s o f Wastes and Waste E f f l u e n t s , i n L. L. C i c c i o (Ed.), Water and Water P o l l u t i o n Handbook, V o l . 1 , Marcel Dekker, New York, 1971, Ch. 7. 44 A. P. A l t s h u l l e r , A n a l y t i c a l Problems i n A i r P o l l u t i o n C o n t r o l , Proc. E n v i r o n . Q u a l . Sensor Workshop, Las Vegas, NV, EPA, Washington, DC 1971, pp 11-44. 45 L. A. R i t t m i l l e r , B. M. Zonkowski, and I. L. Wadehra, P o l l u t . Eng., 3 (1971) 26-28. 46 Y . S a i j o , Bunseki Kagaku, 21 (1972) 395-402; C.A., 76 ( 1 9 7 2 ) 15808f. 47 D. L . King, Water P o l l u t . Handbook, 2 (1971) 451-481.
24 48 K . Grasshoff, Chem. Oceanogr., (1971) 68-69; C.A., 76 (1972) 37207t. 49 R. C. Kroner and 0. G. Ballinger, Treatise Anal. Chem., Vol. 2 (1971) 343-412. 50 North Atlantic Treaty OrganizationlConittee on Challenges to Modern Society, Brussels, Belgium. Air Quality Criteria, Sulfur Oxides (N-7), Particulate Matter (N-8),Carbon Monoxide(N-lo), Nitrogen Oxides (N-15). Photochemical Oxidants and Related Hydrocarbons (N-29). U. S . Government Environmental Protection Agency, Research Triangle Park, NC, 1974. 51 Division of Medical Sciences, Biological Effects o f Atmospheric Pollutants, Fluorides ISBN-0-309-01922-2( 1971); Asbestos ISBN-0-309-01927-3, Lead ISBN-0-309-01941-9, and Particulate Organic Matter ISBN-0-309-02027-1 (1972) : Medical and Biological Effects of Environmental Pollutants, Manganese I SB N-0-309-0 2 143-X ( 1973 ) , Chr omi um I SB N-0-309-022 1 7- 7, Van adi um ISBN-0-309-02218-5, and Nickel ISBN-0-309-0231 4-9( 1974). National Research Council-National Academy of Sciences, Washington, DC, Vapor Phase Organic Pollutants-Volatile Hydrocarbons and Oxidation Products (NTIS-PB 249 357) (1975), Arsenic (NTIS-PB 262 167) (1976), Chlorine and Hydrogen (NTIS-PB 253 96), Ozone and other Photochemical Oxidants (PB 260 570-571, Selenium (NTIS-PB 251 318) (1976). 52 Advisory Center on Toxicology, Short-Term Limit Reports, Oxides of Nitrogen PB-199 903, Basis for Guides PB-199 904, Hydrogen Chloride PB-203 464, and Hydrogen Fluoride PB-203 465 (1971); Ammonia PB-244 336 (1972); Carbon Monoxide PB-244 338 and Chlorine PB-244 339 (1973): and Hydrazone, Monomethyl Hydrazine, and 1,l-dimethylhydrazine PB-244 337 (1974). National Research Council-National Academy of Sciences, Washington, DC. 53 World Health Organization, Air Quality Criteria and Guide for Urban Air Pollutants, Tech. Rep. Ser. No. 506, World Health Organization, Geneva 1972. 54 World Health Organization Environmental Health Criteria Programne, Report of a Meeting on Environmental Health Criteria and Standards, Geneva 20-24 November 1972, EP 73/1, World Health Organization Geneva, 1973. 55 Air Quality Abstracts, Pollution Abstracts, LaJolla, CA, 1974. 56 Air Pollution Technical Information Center (APTIC) Air Pollution Abstracts, U.S. Gov't. Printing Office, Washington, DC. 57 D. L. Brenchley, C. D Turley and R. F. Yarmac, Industrial Source Sampling, Ann Arbor Sci. Publ., Ann Arbor, MI, 1973. 58 M. Sittig, Pollution Detection and Monitoring Handbook, Noyes Data Corp., Park Ridge, NJ, 1974. 59 T. Cercer, Aerosol Technology in Hazard Evaluation, Academic Press, New York, 1 976. 60 Environmental Instrumentation Group, Instrumentation for Environmental Monitoring Air, 1st ed., Lawrence Berkeley Laboratory, University o f California, Berkeley, CA, May 1972: updates: Feb. 1973, Dec. 1973. 61 Air Sampling Instruments Committee, ACGIH, Air Sampling Instruments, 4th ed., American Conference of Governmental Industrial Hygienists, Cincinnati, OH, 1972.
Chapter 3
SAMPLING TECHNIQUES
3.1
INTRODUCTION
Sampling i s t h e o p e r a t i o n o f r e m o v i n g a p a r t ( o f c o n v e n i e n t s i z e ) f r o m t h e whole i n such a manner t h a t t h e sample r e p r e s e n t s , w i t h i n m e a s u r a b l e l i m i t s o f e r - r o r , t h e p r o p o r t i o n o f t h e q u a n t i t y i n t h e whole. The p r i n c i p l e s o f s a m p l i n g a r e o f
importance t o t h e a n a l y t i c a l chemist f o r
several reasons: (1)
The g r e a t e s t c a r e t a k e n i n p e r f o r m a n c e o f t h e a n a l y s i s may be i n v a i n
i f t h e sample has been o b t a i n e d c a r e l e s s l y ;
i t i s n o t r e p r e s e n t a t i v e of
i.e.,
the
system be i ng samp I ed.
(2)
The
p r o p e r method o f
t r e a t i n g t h e sample(s)
i s dependent
upon
the
purpose o f t h e sampling. Methods o f
a n a l y s i s a r e m o r e p r e c i s e t h a n m o s t samp I i n g p r o c e d u r e s .
it i s possible t o determine t h e c o n t r i b u t i o n o f
Through e x p e r i m e n t a t i o n
errors of
a n a l y s i s and s a m p l i n g t o t h e t o t a l v a r i a b i l i t y o f r e s u l t s and t o c o n t r o l t h e combined procedure accordingly. of
subdivisions of
a
An economic b a l a n c e s h o u l d be m a i n t a i n e d between t h e number lot
( t h e b u l k sample) o f
material
that
a r e sampled
and t h e
number of subsamples from each s u b d i v i s i o n . To p e r f o r m t h e j o b p r o p e r l y , one s h o u l d know as much as p o s s i b l e a b o u t t h e n a t u r e and c o n d i t i o n o f m a t e r i a l s t o be sampled, and have adequate knowledge a b o u t a n a l y t i c a l
t h e t o o l s t o be used i n t h e s a m p l i n g
methodology.
One o f
sampling
i s t o j u d g e a c c e p t a b i l i t y o f t h e sample.
Most o f t e n ,
because
one
it
wishes
to
know
if
For t h i s purpose,
specifications.
the
material
t h e purposes o f
a sample
represents
meets
i s taken certain
t h e sample must a c c u r a t e l y r e p r e s e n t t h e whole
q u a n t i t y ( t h e p o p u l a t i o n a v a i l a b l e ) under c o n s i d e r a i i o n . Another f a c e t o f t h e a c c e p t a b i I i t y i s t o a s s u r e t h e absence o f c o n t a m i n a t i o n or d i r t from m a t e r i a l b e i n g sampled.
F o r t h i s i m p o r t a n t purpose,
it i s usually
p r e f e r a b l e t o sample i n a way t h a t g i v e s maximum a s s u r a n c e o f f i n d i n g c o n a m i n a t i o n , i f t h e c o n t a m i n a t i o n p r e s e n t does n o t a c c u r a t e l y r e p r e s e n t t h e b u l k q u a n t i y.
A t h i r d p u r p o s e o f s a m p l i n g i s t o i d e n t i f y unknown m a t e r i a l s . of
obtaining
an
accurate
sample
may
not
be
warranted
because
The expense a
particular
c o n t a m i n a t i o n does n o t p e r s i s t l o n g enough t o e s t a b l i s h i t s i d e n t i t y . Sampling t e c h n i q u e s f o r e n v i r o n m e n t a l samples i n c l u d e t h e t h r e e s t a t e s o f matter:
gas,
l i q u i d and s o l i d .
We w i l l
s u r v e y each o f t h e s e i n r e f e r e n c e t o w a t e r
26 and a i r p o l l u t i o n . A number o f r e s t r i c t l o n s are placed on a l l sampling methods.
c o l l e c t e d must represent t h e c o n d i t i o n s a t t h e t i m e o f sampling.
The samples
To p e r m i t accuracy
of t e s t i n g t h e samples must be o f s u f f i c i e n t volume and number t o f u i f i l l t h e reasons f o r t h e sampling.
The samples must be c o l l e c t e d ,
labeled, packed,
shipped and mani-
p u l a t e d p r i o r t o l a b o r a t o r y treatment i n such a way t h a t these processes minimize any changes i n a p a r t i c u l a r canponent o f i n t e r e s t o r sample p r o p e r t i e s t o be examined. The t i m e i n t e r v a l
between sampling and a n a l y s i s should be l i m i t e d f o r
a
number o f reasons:
(A)
decrease a d s o r p t i o n of gases and s o i l d s from sample t o w a l l s o f t h e
cont a iner ; (B)
(C)
minimize sample loss because o f leaks; decrease p o s s i b i l i t y of chemical changes because o f
i n t e r a c t i o n s of
sample components o r photochemical decomposltlon. The p h i l o s o p h y b e h i n d t h i s t i m e r e s t r i c t l o n
I s t h a t a minimum t i m e
I n t e r v a l between sampling and a n a l y s i s decreases t h e chances f o r any change i n t h e sample ( p h y s i c a l or chemical).
3.2
BACKGROUND AND GENERAL DISCUSSION
A number o f g e n e r a l r e f e r e n c e s a r e a v a i l a b l e t o t h e p e r s o n d e s i r i n g a d d i t i o n a l i n f o r m a t i o n on t h i s very important aspect o f environmental a n a l y s i s ( r e f s . 1-13). The volume o f sample c o l l e c t e d should be h e l d t o a minimum, c o n t r o l l e d by t h e volume needed f o r an accurate a n a l y s i s .
t h e sample volume by t h e lower l i m i t s o f p r e c i s i o n and accuracy, a volume a t l e a s t 2.5 t i m e s t h i s optimum value.
i t s s i z e being
I t i s not wise t o choose but r a t h e r t o choose
The number o f samples taken should
be s u f f i c i e n t so t h a t one may assume a r e p r e s e n t a t i v e sampling has been completed. T h i s i s n o t always p o s s i b l e as t h e t i m e ( t o sample and analyze) and cost are u s u a i i y important parameters. lake, r e s e r v o i r , e t c . , sample s i t e (e.g.,
A compromise must be made e s p e c i a l l y when sampling from a where a s i n g l e sample w i i l p e r m i t minimum i n f o r m a t i o n .
lake o r other large body o f water) i s fed by smaller streams, then
i t becomes important t o sample above and below t h e p o i n t o f entrance t o t h e
site.
I f the
large
The non-movement o f the water i n a lake makes i t more d i f f i c u l t t o p o i n t out
waste contamination by sampling a t one s i t e than f l o w i n g stream.
Measurement o f the c o n c e n t r a t i o n and volume o f
waste streams i s very important. are not useful
i f t h e sample were taken from a
alone;
r e c e i v i n g waters.
they must be i n t e r p r e t e d
Thus,
waste m a t e r i a l
in
Concentrations o f t h e p o l l u t a n t s i n waste e f f l u e n t s
flow r a t e s o f
i n terms o f
interactions with the
both t h e daste streams
and t h e r e c e i v i n g
waters must be known. Contamination
of
water
results
from
three
broad groupings:
dissolved
27 gases, d i s s o l v e d l i q u i d s and s o l i d s ,
and p a r t i c u l a t e s o l i d s .
Oxygen i s p r o b a b l y t h e
most commonly d i s s o l v e d gas measured i n a q u a t i c environments.
I f one i s i n t e r e s t e d
i n BOD ( b i o l o g i c a l oxygen demand) or COD (chemical oxygen demand) values,
then t h e
c o n c e n t r a t i o n o f d i s s o l v e d oxygen should be determined a t l e a s t t w i c e each sampling day
-
a t midafternoon and very e a r l y
i n t h e morning b e f o r e t h e sun r i s e s .
d i o x i d e i s another gas o f considerable i n t e r e s t f o r aquatic s t u d i e s . arises
because o t
t h e carbonate-bicarbonate
b u f f e r system
in a l l
Carbon
I t s importance water
systems.
However, t h e a n a l y s i s of f r e e carbon d i o x i d e i s not a u s e f u l endeavor because o f t h i s b u f f e r i n g system which i s present. Dissolved sol i d substances are d e f i n e d as those which pass t h r o u g h a 0.45 filter.
N i t r o g e n and phosphorus n u t r i e n t s ,
c h l o r i d e , s u l f a t e and carbonate s a l t s ,
and heavy metals and cyanide ( t o x i c m a t e r i a l s ) are t h e predominately d i s s o l v e d i o n i c inorganic s o l i d s .
With t h e exception o f t h e carbonate-bicarbonate b u f f e r system,
w h i c h s e r v e s as a r e s e r v e c a r b o n s o u r c e f o r
photosynthesis ( r e f .
14),
these
inorganics do not show much d i u r n a l v a r i a t i o n ( r e f . 15). Dissolved organic m a t e r i a l s g e n e r a l l y may be c l a s s i f i e d as:
( 1 ) those d i s s o l v e d n o n t o x i c o r g a n i c s present i n waste waters.
These a r e
an energy source f o r t h e h e t e r o t r o p h i c m i c r o b i o t a both i n t h e r e c e i v i n g waters and They are r e f e r r e d t o as biodegradable o r g a n i c substances.
t h e waste waters.
( 2 ) those d i s s o l v e d organics which a r e formed d u r i n g anaerobic f e r m e n t a t i o n o f organic wastes ( r e f . This t y p e o f
13).
These are n o t t o x i c t o
d i s s o l v e d organic
material
nor used by a q u a t i c b i o t a .
i s responsibile
for
t a s t e and odor
and
u s u a l l y may be c o l l e c t e d on carbon f i l t e r s . ( 3 ) those d i s s o l v e d o r g a n i c s which are t o x i c t o a q u a t i c b i o t a and which may be found i n n a t u r a l as w e l l as waste waters, e.g., The
dissolved
organic
materials
organic pesticides.
are
usually
present
in
much
concentrations than inorganics, mainly because o f t h e i r low s o l u b i l i t y i n water. t o their needed
Due
low c o n c e n t r a t i o n , more p r e c i s e and s o p h i s t i c a t e d a n a l y t i c a l techniques a r e for
identification
and
measurement,
e.g.,
extractions,
chrdmatographic
The i n o r g a n i c f r a c t i o n o f p a r t i c u l a t e s o l i d s i s m a i n l y
a n a l y s i s and spectroscopy. silt,
lower
sand and c l a y s o i l p a r t i c l e s ,
b u t t h e o r g a n i c f r a c t i o n may be e i t h e r l i v i n g o r
dead organic m a t e r i a l s . Sampling
volatile
constituents
components,
and
atmospheres
for
analysis.
Most analyses of t h i s t y p e deal w i t h t r a c e q u a n t i t i e s o f i m p u r i t i e s ,
and
l a r g e samples a r e u s u a l l y necessary ( r e f . phosgene,
mustard gas,
removal
16).
i e w i s l t e or chloride)
of
requires
sample
f o r t h i s reason,
of
contaminated
collection,
p o l l u t a n t s (e.g.,
concentration
of
efficient
Density of gaseous usually counteract
d i f f u s i o n processes t o t h e e x t e n t t h a t i t may cause s t r a t i f i c a t i o n ( r e f . for
t h i s reason t h a t
one
should
not
depend
upon
diffusion
17).
It i s
processes t o produce
homogeneous mixtures i n most cases. There are a number o f e f f e c t s which can r e s u l t i n c o n c e n t r a t i o n e r r o r s I n
28 many sampling techniques ( r e f .
(1)
18).
adsorption on w a i l s and connecting tubes,
( 2 ) s o l i d adsorbent c o l l e c t i o n system e f f e c t s , mechanical d e f e c t s i n equipment, effects,
( 3 ) d i f f u s i o n through p l a s t i c s ,
( 5 ) p a r t i a l vapor pressure e f f e c t s ,
17) temperature e f f e c t s ,
( 8 ) volumetric errors,
(4)
(6) s o l u b i l i t y
( 9 ) e r r o r s o f observation,
and (10) e r r o r s i n sampling r a t e . Most sampl i n g systems components:
(1)
for
airborne
usual l y
pollutants
i n t a k e and t r a n s f e r s e c t i o n ;
consist
( 2 ) c o l l e c t i o n device;
of
four
( 3 ) flow
measuring component, and ( 4 ) component t o keep a i r moving through t h e system. Each o f these components must perform p r o p e r l y f o r a successful sampling scheme.
One may consider t h e sampling system as t h e r e c e p t o r f o r t h e component or
e f f e c t t o be measured.
Any subsequent changes considered must be done w i t h r e f e r r a l
t o t h e receptor and what consequences t h e r e c e p t o r may have upon t h e success o f t h e sampl ing. Ambient a i r q u a l i t y i s influenced by t h e various m e t e r o l o g i c a l parameters existing
at
the
precipitation, radiation).
time
wind
of
the
velocity
sampling
and
(e.g.,
direction,
stability humidity,
of
the
temperature
Temperature decreases as one goes higher i n a l t i t u d e .
t o as lapse r a t e ;
and,
and
solar
This i s r e f e r r e d
C/lOOO m ( r e f . 19).
i t i s 9.8'
f o r dry a d i a b a t i c a i r ,
atmosphere,
The
l e v e l s o f a i r p o l l u t i o n a t ambient c o n d i t i o n s have been found t o be i n v e r s e l y r e l a t e d t o the wind v e l o c i t y ( r e f . 20). When choosing a sampling s i t e f o r continuous monitoring,
i t i s necessary t o
consider t h e proper s i t i ng o f t h e samp I ing system t o p r o v i d e ' proper r e p r e s e n t a t i o n and t o consider t h e s i t e s i n reference t o each o t h e r
(refs.
should be considered when s e l e c t i n g a sampling s i t e are: s h o u l d n o t be
lower t h a n 2 m above
contaminants a t E a r t h ' s surface, p r o t e c t e d from t h e wind by t a l l
ground
level
21-25).
Items which
( a ) t h e sampling
inlets
t o minimize c o l l e c t i o n o f
( b ) sampling s i t e s should not be located on t h e s i d e buildings,
accessible and secure from tampering,
( c ) t h e sampling s i t e should be e a s i l y
( d ) t h e i n t a k e o f t h e sampler should n o t be
exposed d i r e c t l y t o l o c a l i z e d p o l l u t i o n sources,
(e.g.,
chimney),
and ( e l t h e s i t e
should have adequate e l e c t r i c a l power f o r m a i n t a i n i n g t h e equipment. Two terms commonly
found
in
the
s o u r c e s a m p l i n g and e m i s s i o n s a m p l i n g . interchangeably,
however,
environmental
sampling
literature
These t w o t e r m s a r e v e r y o f t e n used
they mean d i f f e r e n t
things.
considered as t h e sampling o f t h e environmental
Source sampling should be
pollutants at their
source,
b e f o r e they have a chance t o e n t e r t h e atmosphere and become d i l u t e d . On hand,
are
the
i.e., other
emission source sampling r e f e r s t o t h e sampling o f t h e p o l l u t a n t s once they
have entered t h e atmosphere and a r e d i l u t e d .
Emission sources a r e u s u a l l y monitored
t o determine mass emission r a t e o f
p o l l u t a n t s from a
certain
source,
t o obtain
emission data from a number o f sources f o r i n p u t data t o an a i r q u a l i t y model and t o evaluate c o n t r o l devices which have been i n s t a l l e d a t c e r t a i n sources o f p o l l u t i o n .
The s a m p l i n g and a n a l y s i s o f a i r and w a t e r
i s of
i n t e r e s t because
it
c o n c e r n s a t o p i c w h i c h i s c o n t e m p o r a r y and i t uses t e c h n i q u e s and p r i n c i p l e s w h i c h may or may n o t be f a m i l i a r t o most s c i e n t i s t s . continually
New e n v i r o n m e n t a l
b e i n g e n a c t e d and o l d ones b e i n g r e l a x e d .
r e s t r i c t i o n s are
Environmental a i r problems
have t o i n c l u d e a l l volumes o f a i r s t a r t i n g a t t h e s u r f a c e o f t h e E a r t h t o a d i s t a n c e a t l e a s t 7 m i l e s above t h e E a r t h ' s s u r f a c e .
T h i s gaseous s y s t e m i s commonly known as i t be
a i r and s h o u l d have t h e c o m p o s i t i o n ( w h e t h e r
(78.08%). O2 K r , Xe,
(20.95$),
and He.
indoors o r out-of-doors):
N2
C02 (0.034%), A r (0.93%), and s m a l l e r p e r c e n t a g e s o f H2, Ne,
O t h e r components can be c l a s s i f i e d as c o n t a m i n a n t s .
o f c o n t a m i n a n t s we f i n d s u c h t h i n g s as h y d r o c a r b o n s ,
In t h e category
carbon monoxide,
compounds, n i t r o g e n compounds, m e t a l s , m e t a l i o n s , v a r i o u s o x i d a n t s ,
sulfur
pesticides, etc.
As has been p o i n t e d o u t by A x e l r o d and Lodge ( r e f . 2 6 ) . " p u r e a i r " p r e s e n t s a p r o b l e m o f d e f i n i t i o n because even t h e p u r e s t a i r t h a t we can sample on e a r t h , s t a t e , w i I I c o n t a i n hundreds o f c o n t a m i n a n t s . operational d e f i n i t i o n :
"pure a i r "
t o i n t e r f e r e with the analysis.
Thus,
i n the natural
t h e b e s t we can do i s t o use an
i s t h e n t h e a i r w h i c h i s f r e e o f a n y t h i n g known
Environmental
w a t e r p r o b l e m s have t o
m a t e r i a l ( s 1 w h i c h may b e i n j u r i o u s t o t h e w e l l - b e i n g o f m a n k i n d .
i n c l u d e any Here,
water
p r o b l e m s have v a r i o u s o r d e r s o f magnitude,
d e p e n d i n g u p o n w h i c h w a t e r we a r e
d i s c u s s i n g and f o r what use i t i s i n t e n d e d .
The p r o b l e m s o f o d o r s e m a n a t i n g f r o m
water
s u p p l i e s e n t e r s t h e a r e a o f b o t h water and a i r p o l l u t i o n .
I f t h e purpose o f
t h e s a m p l i n g and a n a l y s i s i s t o d e t e r m i n e whether t h e s o u r c e o f t h e o d o r w a t e r , t h e n i t i s a water p o l l u t i o n problem. odor,
i s in the
I f t h e purpose i s j u s t t o i d e n t i f y t h e
t h e n i t c o u l d r i g h t l y be c l a s s i f i e d as an a i r p o l l u t i o n p r o b l e m . I n t h e U.S.A.,
air
and water
q u a l i t y s t a n d a r d s have been i s s u e d b y t h e
E n i v i r o n m e n t a l P r o t e c t i o n Agency (EPA) ( r e f s . 27 and 28). u p d a t i n g and o t h e r
c o n t a m i n a n t s need t o be added t o
the
These a r e a l l I ist.
i n need o f
E n c l o s e d and/or
w o r k i n g a r e a s have had r e s t r i c t i o n s p l a c e d on them by OSHA ( O c c u p a t i o n a l S a f e t y and Health Administration) Health).
and
NIOSH
(National
Institute of
Occupational
Safety
and
I n C h a p t e r 8, t h e a u t h o r s have t a b u l a t e d a l l s t a n d a r d s t h r o u g h o u t t h e w o r l d
w h i c h a r e known or a v a i l a b l e a t t h e t i m e o f t h i s p r i n t i n g .
3.2.1
Theory and s t a t i s t i c a l
foundation o f samDlinq
A f i t t i n g way t o s t a r t t h i s s e c t i o n would be t o g i v e a d i r e c t q u o t e f r o m a c h a p t e r on t r a c e a n a l y s i s b y gas c h r o m a t o g r a p h y w r i t t e n by U m b r e i t ( r e f .
29).
IIIn
t h i s s o c i e t y we have r e a c h e d t h e p o i n t o f e n a c t i n g laws p r o v i d i n g r u l e s l i m i t i n g a t trace
levels the discharge o f
a wide v a r i e t y o f
s p e c i f i c compounds
e n v i r o n m e n t and have p r o v i d e d p e n a l t i e s f o r e x c e e d i n g such l i m i t s . even though t h e r e i s r e a s o n a b l e u n c e r t a i n t y compounds a t t r a c e measurements,
levels,
regulatory action
i n t o our
As a consequence,
i n the identification of i s t a k e n on t h e b a s i s o f
specific analytical
i n many c a s e s w i t h o u t r e g a r d t o an e v a l u a t i o n o f t h e a c c u r a c y o f t h e s e
measurements."
The a u t h o r s f e e l t h e passage speaks f o r
i t s e l f and no f u r t h e r
explanation i s necessary. The j u s t i f i c a t i o n f o r
sampling
i s q u i t e an easy
task
if
one considers
analyzing a l l p o s s i b l e a i r / a n d water environments on a c o n t i n u i n g basis. and cost,
however,
So,
are l i m i t i n g f a c t o r s t o such a p r o j e c t .
sampling program we should answer a number of questions.
The t i m e
before we begin a
I s our o b j e c t i v e t o secure
data about every a i r and water p o p u l a t i o n ( p o p u l a t i o n meaning every u n i t which goes t o make up a body o f w a t e r , environments, e.g., information of
t h e o u t s i d e a i r o f t h e environment,
confined a i r
work areas or a h o s p i t a l ) o r i s it o n l y necessary t o o b t a i n exact Also,
r e p r e s e n t a t i v e p a r t s o f these p o p u l a t i o n s ?
do we need t h i s
i n f o r m a t i o n on a c o n t i n u i n g b a s i s or f o r a s p e c i f i e d p e r i o d o f t i m e ? do we want t o know i f a l e v e l o f t o x i c i t y has been exceeded,
I n o t h e r words,
o r do we wish t o know
what t h e level o f contamination i s a t a p a r t i c u l a r t i m e and l o c a t i o n . questions come down t o are: have t o be?
What these
f o r what i s t h e data t o be used and how accurate does i t
One must r e a l i z e t h a t a c e r t a i n l e v e l of e r r o r w i I I be present i n t h e
sampling processes as w e l l as i n t h e measuring processes. t h e sampl i n g and measuring steps should be compatible.
The degree o f accuracy o f
By t h a t we mean, do not use a
very e l a b o r a t e sampling scheme when your measuring step i s accurate enough o n l y t o g i v e a yes or no answer as t o whether a c e r t a i n l e v e l has been exceeded.
Conversely,
one would not use an unplanned sampling procedure when t h e measuring step must have a very high degree of accuracy and p r e c i s i o n .
Conclusions drawn about t h e p o p u l a t i o n
from a sample may be completely d i f f e r e n t from t h e a c t u a l p o p u l a t i o n values.
This
d i f f e r e n c e i s mainly dependent upon t h e sampling survey r a t h e r than on t h e analyses o f t h e samples. Sampling e r r o r u s u a l l y decreases w i t h an increase i n sample s i z e ( i . e . , number o f u n i t s n s e l e c t e d i n t h e s a m p l i n g ) .
In fact,
the
i n many s i t u a t i o n s t h e
decrease i s i n v e r s e l y p r o p o r t i o n a l t o t h e square r o o t o f n (sample
size).
Sampling
e r r o r i s t h e e r r o r a r i s i n g from drawing inferences about t h e p o p u l a t i o n ( b u l k sample) on t h e b a s i s o f observations on a p a r t o f t h e p o p u l a t i o n ( t h e samples). shows t h a t sampling e r r o r decreases s u b s t a n t i a l l y as n increases,
however,
Fig.
increasing
sample r a t e becomes a marginal c o n s i d e r a t i o n as n continues t o increase. comment may be s a i d f o r t h e r e l i a b i l i t y o f t h e a r i t h m e t i c means, t h e number of measurements.
R,
3.1
A similar
as compared t o
In o t h e r words, t h e r e l i a b i l i t y o f t h e mean increases as
t h e square r o o t o f n (number o f measurements).
The mean i s 3 times as r e l i a b l e as t h a t of a s i n g l e measurement when n=9; The mean i s 4 times as r e l i a b l e as t h a t o f a s i n g l e measurement when n=16, etc.
L e t us look a t t h e sampl i n g process on a m r e q u a n t i t a t i v e b a s i s . we wish t o analyze a body o f i n s e c t i c i d e 2,4-0.
water
(e.g.,
a
I f we sampled t h e e n t i r e
lake) lake,
Suppose
f o r the concentration of our p o p u l a t i o n sampling
the
units
31
SAMPLING SIZE, n
F i g . 3.1 Sampling e r r o r change w i t h an increase i n humber o f samples.
would be N ( a p o p u l a t i o n ) . of
$EN.
A n a l y s i s of a l l these samples would p r o v l d e an e r r o r ,
T h i s e r r o r would be due t o t h e presence o f non-sampl i n g e r r o r s because we
sampled and analyzed t h e e n t i r e p o p u l a t i o n . n,
frcm t h e population,
samples (i.e.,
N,
I f we s e l e c t e d a random s e t of samples,
t h e p o p u l a t i o n e r r o r r e s u l t i n g from t h l s f i n i t e s e t o f
t h e divergence from t h e t r u e value, sample e r r o r ,
composed of two t y p e s o f e r r o r :
%En,,
would be $En
$En would be
and non-samp I 1 ng e r r o r ,
JEn2*
We may now d e f i n e some o t h e r terms:
CN = c o s t o f c o l l e c t i n g and a n a l y z i n g d a t a f o r each sample f r o m t h e population (N). Cn = c o s t of c o l l e c t i n g and a n a l y z i n g data f o r each sample i n t h e f i n i t e
set of samples ( n ) . Now CN should be greater than Cn; I n many cases, survey
however,
nCn should be less than NCN.
t h e sampling and non-sampling
f o r a c o r r e c t size,
n,
will
errors,
%En,
i n t h e sample
probably be l e s s than t h e non-sampling
errors,
32 $EN.
The t o t a l c o s t f o r any given sample s i z e can be w r i t t e n :
nCn + LE,
+
(3.1 1
LEn2
where L = loss involved i n making d e c i s i o n s on the survey r e s u l t s ,
i.e.,
l o s s per 1 %
error. So as n Increases,
LEnl.
would decrease.
minimum,
t h e components nCn and LEn2 would
increase,
whereas,
The value o f t h e sample s i z e n where t h e t o t a l c o s t reaches a
i s considered t h e optimum sample s i z e n.
This cost w i l l
go through a
minimum (see Fig. 3.2).
SlMPLlWC WE,n
F i g . 3.2 R e l a t i o n s h i p of sampling c o s t compared t o number o f samples taken.
The r e l a t i v e standard e r r o r o f t h e sample mean
2
from t h e measurement o f n
samples c o l l e c t e d by simple random sampling w i t h o u t replacement i s given b y
C t R ) = [(N-n)/(N-l
)]'/2C/(nl'/2
(3.2)
where C = p o p u l a t i o n c o e f f i c i e n t o f v a r i a t i o n .
To insure a r e l a t i v e standard e r r o r o f $e, we need a sample size, n, o f n = NC'/C(N-I)~
2 + c 21
(3.3)
33 random sample
A
randomness,
i.e.,
i s one
whose
selection
i s based on
the theory
i t i s a s a m p l e d r a w n i n s u c h a manner t h a t e a c h u n i t
p o p u l a t i o n h a d an e q u a l p r e d e t e r m i n e d p r o b a b i l i t y o f b e i n g s e l e c t e d .
of
in the Thus,
a
p r o b a b i I i t y s a m p l i n g scheme would be one i n which:
( 1 ) each p a r t ( i n d i v i d u a l sample
from
being taken,
the population)
has an e q u a l
probabiity
of
( 2 ) these discrete
samples a r e chosen by a random p r o c e s s t h a t i s c o n s i s t e n t w i t h t h e p r o b a b i l i t i e s ,
and
( 3 ) t h e a n a J y s i s o f t h e s e d i s c r e t e samples i s based upon w e i g h t s c o n s i s t e n t w i t h t h e p r o b a b i l i t i e s s e t i n s t e p one ( r e f . 3 0 ) . I f we s a m p l e n p a r t s , samples
N
is
(n)
w i t h equal
probability,
t h e number o f p o s s i b l e N i s l / ( n ) .The c o s t
and t h e s e l e c t i o n p r o b a b i l i t y o f each sample
f u n c t i o n o f a s a m p l i n g program, C,
can be e s t i m a t e d by ( r e f . 3 1 )
+ nC,
C = C whare C
C
(3.4)
= t h e o v e r h e a d c o s t s f o r t h e program
1
n
= t h e a v e r a g e c o s t o f a n a l y z i n g one sample u n i t = t h e number of sample u n i t s i n t h e program.
Laboratory
samples
for
quantitative
analysis
are
r e p r e s e n t a t i v e o f t h e p o p u l a t i o n l o t from w h i c h t h e y were drawn. such as samples f r o m a c l e a r sample.
Environmental
population;
solution,
samples,
on
assumed
to
be
For u n i f o r m samples
any one p o r t i o n w o u l d be a r e p r e s e n t a t i v e
the
whole,
are
collected
from
a
non-uniform
so t h e u s u a l p r a c t i c e i s t o s e l e c t a number o f p o r t i o n s t o c o n s t i t u t e t h e
sample on t h e b a s i s t h a t t h e a v e r a g e v a l u e of t h e component
i n t h e sample w i l l
be
e s s e n t i a l l y t h e same as t h e a v e r a g e t h a t w o u l d be f o u n d i f t h e e n t i r e l o t had been analyzed.
R u l e s o f thumb from p a s t e x p e r i e n c e and i n t u i t i o n ace o f t e n r e l i e d upon
f o r t h e s e purposes.
A p r o b a b i l i t y sample w o u l d f u r n i s h c r i t e r i a f o r e s t i m a t i n g t h e
sample s i z e r e q u i r e m e n t and p r e c i s i o n t o be a c h i e v e d w i t h m r e r e l i a b i l i t y . A
p r o b a b i l i t y s a m p l i n g p l a n makes use o f
the theory
of
probability
to
s e l e c t sample p o r t i o n s o r i t e m s w i t h a p p r o p r i a t e p r o c e d u r e s for s u m m a r i z i n g t h e t e s t results.
I n t h i s way a v a l i d o b j e c t i v e e v a l u a t i o n may be made o f t h e p r o b a b l e l i m i t s
o f sample e r r o r . A p o p u l a t i o n m a t e r i a l may be c o n c e i v e d as composed o f N d i s t i n c t p o r t i o n s
of units,
each p o s s e s s i n g t h e g i v e n p r o p e r t y b u t n o t n e c e s s a r i l y t o t h e same e x t e n t
o r magnitude.
The u n i t s may be i n d i v i d u a l
p o p u l a t i o n by means o f a s a m p l i n g d e v i c e .
i t e m s o r s m a l l q u a n t i t i t e s t a k e n from a Any group o f n u n i t s c o u l d be c o n s i d e r e d
a sample o f t h i s u n i v e r s e i f t h e n u n i t s have been i n d e p e n d e n t l y s e l e c t e d a t random. Such a sample w o u l d p e r m i t c e r t a i n i n f e r e n c e s t o be drawn;
and,
from these inferen-
ces, one c o u l d answer a v a r i e t y o f q u e s t i o n s a b o u t t h e p o p u l a t i o n . If
t h e sampling i s performed c o r r e c t l y ,
a second p r o b a b i l i t y sample o f n
u n i t s drawn from t h e same p o p u l a t i o n s h o u l d have an a v e r a g e v a l u e or r a n g e o f v a l u e s e s s e n t i a l l y o f t h e same o r d e r o f magnitude.
34 An important p a r t o f a sampling plan i s t h e d e t e r m i n a t i o n o f t h e number o f samples needed so sample averages w i l l have t h e r e q u i r e d p r e c i s i o n .
The c a l c u l a t i o n
o f minimum sample s i z e r e q u i r e s an advance estimate o f t h e standard d e v i a t i o n o f t h e u n i t s i n t h e sample population.
A f a i r l y good e s t i m a t e may be d e r i v e d from t h e range
(lowest t o highest value i n t h e sample u n i t s ) o f t h e p r o p e r t y t o be determined and t h e shape o f t h e d i s t r i b u t i o n curve. (a)
If
data values r u n r a t h e r
u n i f o r m l y throughout
t h e range,
w,
the
standard d e v i a t i o n , s, w i l l be about 0 . 3 ~ . (b)
I f t h e d i s t r i b u t i o n o f data values i s skewed ( l y i n g a t one end o r t h e
o t h e r ) , then t h e standard d e v i a t i o n , s w i l l be about 0 . 2 5 ~ . (c) deviation,
s,
I f t h e data values are predominantly i n t h e middle,
t h e standard
i s about 0 . 2 ~ .
A level o f p r e c i s i o n must be s p e c i f i e d ,
1.e..
we must decide:
(1)
what
d i f f e r e n c e can be t o l e r a t e d between t h e estimate t o be made from t h e sample and t h e r e s u l t t h a t would be obtained by t e s t i n g every u n i t i n t h e population, r i s k i s acceptable i f t h e t o l e r a n c e i s exceeded ?
and ( 2 ) what
Keep i n mind t h a t t h e smaller t h e
t o l e r a n c e or t h e r i s k , t h e l a r g e r w i l l be t h e sample s i z e r e q u i r e d . Most evironmental samples may be considered single-stage universe c o n s i s t s o f N u n i t s , n o f which may be drawn as samples,
n = (to/€)
sampling.
I f the
then ( r e f . 29)
2
(3.5)
where n lum) i n t h e troposphere.
At
A
n e g l i g i b l e f r a c t i o n o f aerosol p a r t i c l e s i s i n normal s t r a t o s p h e r i c a i r . The v a r i a t i o n i n p a r t i c l e s i z e may be due t o t h e shape o f
the p a r t i c l e
38 (which w i l l
affect
its
aerodynamic
properties),
the density
and v e l o c i t y
(which
a f f e c t s i n e r t i a and e l e c t r i c a l charges). The momentum o f aerosol p a r t i c u l e s (product o f source of e r r o r i n aerosol sampling. and each time t h e flow original
i t s mass and v e l o c i t y ) i s a
Aerosol p a r t i c l e s a r e l a r g e r than gas molecules
d i r e c t i o n changes t h e
l a r g e r p a r t i c l e s c o n t i n u e on t h e i r
l i n e and are displaced somewhat from t h e o r i g i n a l p a r t o f t h e gas stream.
The problem becomes more severe as p a r t i c l e s i z e and v e l o c i t y increase.
Thus,
it i s
necessary f o r a l l p a r t s o f t h e stream t o be sampled and p r o p e r l y weighted so t h a t a r e p r e s e n t a t i v e sample i s obtained. To insure t h a t t h e r e i s no change i n momentum and t h a t t h e sample w i I I be r e p r e s e n t a t i v e o f gases,
as well as aeroso\s, one samples i s o k i n e t i c a l i y .
accomplished by using a t h i n - w a l l e d
This i s
tube a l i g n e d w i t h t h e stream flow and drawing
sample i n t o i t a t t h e same l i n e a r v e l o c i t y as t h e stream flow a t t h a t p o i n t .
Reasons
for f a i l u r e t o o b t a i n a t r u l y r e p r e s e n t a t i v e sample may be r e l a t e d t o a number o f
factors : (1)
s t r eam
The a i r f l o w i s always d i s t u r b e d by t h e presence of t h e probe.
(2)
The sampling p o i n t chosen may n o t be r e p r e s e n t a t i v e o f
(3)
Turbulent
t h e whole
. flow could be set up a t t h e p o i n t o f
sampling w i t h t h e
r e s u l t t h a t t h e sample w i l l c o n t a i n more o f t h e smaller p a r t i c l e s t h a n t h e l a r g e r particles. (4)
Sample may be l o s t i n t h e sample l i n e by deposition,
agglomeration or
dispersion.
Studies have shown t h a t ( r e f . 4 1 ) : (a)
l s o k i n e t i c sampling i s dependent upon sample alignment as we1 ve Ioc i t y
as
.
(b)
l s o k i n e t i c c o n d i t i o n s favor t h e c o l l e c t i o n o f a l l p a r t i c l e s i es
(c)
The small mass o f t h e smaller p a r t i c l e s (under 3 ,,m diameter)
.
minimizes i n e r t i a l e f f e c t s . (d)
Slow-moving p a r t i c l e s have l i t t l e or no momentum, thus ambient a i r does not r e q u i r e i s o k i n e t i c c o n d i t i o n s .
The processes t a k i n g p l a c e i n F i g . 3.3 a r e t h e f o l l o w i n g : ( 1 ) F i g . 3.3a
shows i s o k i n e t i c sampling,
i.e.,
c o l l e c t i o n of an amount o f
p a r t i c l e s p r o p o r t i o n a l t o what a c t u a l l y e x i s t s i n t h e stream.
F i g . 3.3
i l l u s t r a t e s the e f f e c t of non-isokinetic
i s o k i n e t i c sampling of
Thus V s = Vn and Cm =
sampling as compared t o
gases ( w i t h or w i t h o u t aerosols or p a r t i c u l a t e s ) .
d e f i n e some terms and symbols.
L e t us
39
SAMPLE
A. ISWINETIC SAMPLING
SAMPLE
I
f
I STREAM LINES
,
Vn*Vs CrnrCt
E SAMPLE VELOCITY TOO LOW NON-ISOKINETIC
SAMPLE
STREAM UNES Ml *vs h 95%.
The study ( r e f . . 2 2 )
showed t h a t p e s t i c i d e s were adsorbed on t h e w a l l s o f t h e s y r i n g e from hexane e x t r a c t s but not
from acetone e x t r a c t s .
S t a l l i n g and H u c k i n s ( r e f .
2 4 ) a n a l y z e d and
c h a r a c t e r i z e d toxaphene i n f l s h and water by an e x t r a c t i o n technique f o l l o w e d b o t h by
94 electron-capture
detection
and
gas
chromatography-mass
spectrometry.
labeled p e s t l c l d e s were e x t r a c t e d from serum w i t h hexane, u s i n g c a p i l l a r y columns c o a t e d w i t h SE-30 o r OV-1
Carbon-14
separated and determined
(ref.
25).
Flunitrazepam,
d e s m e t h y l f l u n i t r a z e p a m and c l o r a z e p a m were e x t r a c t e d f r o m p l a s m a and t h e f i n a l s o l u t i o n was a hexane-acetone ( 4 : l ) mlxture. OV-225
column
using an e l e c t r o n - c a p t u r e
T h l s was separated and analyzed on an
detector
(ref.
26).
Aldlcarb,
aldlcarb
s u l f o x l d e and a l d i c a r b s u l f o n e have been e x t r a c t e d f r o m w a t e r w i t h c h l o r o f o r m , separated on a F l o r l s i l column and detected w i t h a H a l l e l e c t r o l y t l c d e t e c t o r ( r e f . 27).
ppm a l d l c a r b .
Smoke condensate f l a v o r i n g s
have been e x t r a c t e d from ground sausage w i t h d l e t h y l
S e n s l t i v l t y o f t h e method i s 0.05
e t h e r and determined by gas
chromatography ( r e f .
28).
One-tenth
ppm could be detected.
E t h y l e n e t h i o u r e a was
e x t r a c t e d and d e r i v a t l z e d i n one step from water samples ( r e f . 29). and flame-Ionization 4.3.1.2
Electron-capture
d e t e c t l o n were used f o r i d e n t i f l c a t l o n and q u a n t i f i c a t i o n .
Micro-llquid-liquid
e x t r a c t i o n technlque are t h a t one
extractions.
The a d v a n t a g e s o f t h e m l c r o -
i s able t o extract
and c o n c e n t r a t e p o l l u t a n t s
s i m u l t a n e o u s l y and t h e r e i s no p r o b l e m w l t h s u b s e q u e n t e v a p o r a t i o n s . macro-extractlon (carbon-alcohol
methods,
the
CCE
e x t r a c t ) technlques,
(carbon-chloroform
extract)
I n most
and
the
CAE
t h e s o l v e n t phase r e q u i r e s f u r t h e r c o n c e n t r a t i o n
which u s u a l l y r e s u l t s i n s e r i o u s losses o f sample components. Murray ( r e f .
30) developed an e x t r a c t i o n f l a s k 4 l m i l a r t o t h e r a p i d l i q u i d
e x t r a c t i o n technlque used by Grob e t a l .
(ref. 31).
t h i s f l a s k wherein Vo = 200 p& and V w = 980
m.
F l g . 4.1
I s a representatlon of
Murray compared t h l s m i c r o - e x t r a c t i o n
method t o two macro-methods (steam d i s t l l l a t l o n e x t r a c t i o n and a continuous e x t r a c t i o n system).
To show t h e l o s s of s o l u t e d u r i n g t h e e v a p o r a t i o n s t e p ,
n-hexane were made t o c o n t a l n 1.0 ppm o f a group o f o r g a n i c compounds: n-alkanes and phthalates.
standards o f pesticides,
A 10.0 m l a l i q u o t of t h l s standard was then evaporated t o 1
m l and each component i n t h e standard was determined by gas chromatography.
Two
evaporative techniques
The
(micro-Snyder column and r o t a r y e v a p o r a t o r ) were used.
r e c o v e r i e s ranged from 37-842 w l t h t h e micro-Snyder
technlque and 8-100$ w l t h t h e
r o t a r y evaporator. A comparison of t h e r e s u l t i n g chromatograms from t h e m i c r o - e x t r a c t i o n
two macro-methods showed t h a t t h e mlcro-technique spiked s o l u t i o n .
and t h e
y i e l d e d a b e t t e r recovery o f t h e
The data showed a c o n c e n t r a t l o n f a c t o r o f
1250X for t h e micro-
e x t r a c t l o n technique compared t o t h e macro-technique. To emphasize t h e advantage o f a m i c r o - e x t r a c t i o n ,
l e t us present t h e c a l c u l a -
t i o n s f o r a t h e o r e t i c a l system, t h e r e s u l t s o f which a r e i n Table 4.2. t h e t a b l e p o i n t out,
less has been e x t r a c t e d i n t h e 0.200-ml
As t h e data i n
(200 M I )s o l v e n t volume;
however, t h e d e t e c t o r would sense more mass o f t h e p o l l u t a n t than i n t h e o t h e r cases. Thus, t h e advantages one f i n d s a r e t h a t :
( 1 ) t h e s i g n a l from t h e d e t e c t o r i s t h e same
order of magnitude as I f one had e x t r a c t e d w l t h a l a r g e r s o l v e n t volume (l.e., t h e
95 chromatograms
look t h e same) and ( 2 ) t h e evaporation step and
its allied
loss o f
sample were by-passed.
CAPlLLA
F i g . 4.1 Representative m i c r o - e x t r a c t i o n f l a s k .
TABLE 4.2
Comparison o f macro- and m i c r o - e x t r a c t i o n techniques
Sample:
1 t o f waste water c o n t a i n i n g 1 mg/e
n-hexane.
o f contaminant C,
F i n a l volume o f s o l v e n t a f t e r evaporation:
i.e.,
r;
1 ppm.
Solvent
1.00 ml (except 200 u l e x t r a c t ) .
KD o f contaminant C = 15.
2 i n f i n a l Samp I e I Q u a n t i t y o f
h o u n t of C
volume(mg) vo I ume
injected***
inject-
jetted**
(mg)
ed ( u t )
0.4000 0.8696 0.9302 0.9970
100.0 10.0 5.0 0.200 *'remaining
** ***
= 'initial
0.6000 0.1304 0.0698 0.0030
0. 3000 0. 0652 0.0349 0. 0030
50 50 50 0
(V~/(K,,V~
+
50 50 50 50
0.015 0.00326 0.001745 0.00075
3.0003 3.000652 3.000698 3.00075
vW)).
E x t r a d i g i t s c a r r i e d t o demonstrate p o i n t . Amount i n j e c t e d i n a 50
I sample from o r i g i n a l e x t r a c t ,
i.e.,
no e v a p o r a t i o n .
The m i c r o - e x t r a c t i o n technique has been a p p l i e d t o several o f t h e EPA p r i o r i t y p o l l u t a n t methods w i t h a h i g h degree o f success.
A r e c e n t paper by Rhoades and N u l t o n
( r e f . 32) has demonstrated t h i s technique f o r t h e e x t r a c t i o n o f aromatics, p h t h a l a t e s , polynuclear aromatics and phenols.
4.3.2
Gas-liquid extraction I n t h i s system f o r sample treatment t h e s o l v e n t f o r t h e water p o l l u t a n t s i s a
gas ( c l e a n a i r ,
The p o l l u t a n t s which may be e x t r a c t e d by t h i s
n i t r o g e n o r helium).
technique must have a h i g h enough p a r t i a l pressure ( P i ) t h a t t h e y can e a s i l y d i s t r l b u t e between t h e gas and l i q u i d phases,
i.e.,
t h e i r p a r t i a l pressure ( i n terms o f
moles) should exceed t h e i r water s o l u b i l i t i e s (expressed i n m o I e s / I i t e r ) . few
data
available
pol i u t a n t s .
on
the
solubilities
Several reasons
of
the
hydrocarbon
types
can account f o r t h i s discrepancy
There are of
in the
priority
Iiterature:
( 1 ) Hydrocarbons and hydrocarbon t y p e s a r e r e l a t i v e l y i n s o l u b l e i n water and p r i o r t o
environmental r e g u l a t i o n s they were usual i y c l a s s i f i e d slmply as "insoluble18. these r e g u l a t l o n s ,
Due t o
i n many c o u n t r i e s these c o n c e n t r a t i o n s had t o be c a l c u l a t e d because
( 2 ) No one r e a l l y needed t h e
most p o l l u t a n t s a r e present a t t h e ppm o r ppb l e v e l s . data so they were never determined.
( 3 ) I n t h e past,
a n a l y t i c a l techniques were n o t
a v a i l a b l e t o determine these low concentrations. Several
techniques a r e
available
under
the
general
heading o f
gas-liquid
extractions. ( 1 ) Headspace a n a l y s i s o r vapor e q u l l i b r a t i o n ( S e c t i o n 4 . 3 . 2 . 1 ) .
This
is a
A volume of i n e r t gas i s e q u i l i b r a t e d w i t h a known volume o f
t r u e e q u i l i b r i u m system.
water sample ( r e f s . 33-36).
( 2 ) Gas s t r i p p i n g o r purge-and-trap nonequi I i brium technique.
technique ( S e c t i o n 4 . 3 . 2 . 2 ) .
phase c o l l e c t e d by a d s o r p t i o n on a s o l i d ( s e e S e c t i o n 3 . 4 1 , containing a solvent condensed component.
i n which gases o f
i n a t r a p which
This
is a
The water sample i s sparged w i t h an i n e r t gas and t h e gas absorbed by a t r a p
I n t e r e s t are absorbed (see Section 3.7)
I s cooled below t h e b.p.
of
the
or
lowest b o i l i n g gaseous
I n t h i s l a t t e r case t h e c o l d t r a p may c o n t a i n a s o l i d adsorbent o r simply
g l a s s wool ( r e f . 37-42).
( 3 ) Gas-i i q u i d e x t r a c t i o n f r o m a w a t e r sample t o w h i c h has been added a s u f f i c i e n t q u a n t i t y o f a s o l u b l e s a l t (e.g.,
KCI, Na2S04. NaCI, e t c . )
t o Increase t h e
i o n i c s t r e n g t h o f t h e sample ( t h i s i s r e a l l y a m o d i f i c a t i o n o f technique No. The presence o f t h e s a l t decreases t h e s o l u b i l i t y o f
Section 4.3.2.3)).
i (see nonpolar
and/or s l i g h t l y p o l a r organic solutes, t h u s a l l o w i n g more vapor t o e n t e r t h e gas phase ( r e f s . 43 and 4 4 ) . Each o f these w i l l be discussed i n subsequent sections.
Gas-liquid extraction
i s being used more and more i n t h e area o f environmental a n a l y s i s . more d i r e c t a p p l i c a t i o n t o waste water e f f l u e n t s .
I t w i l l soon have
Many organic molecules which were
not p r e v i o u s l y determined by t h i s technique are now e a s i l y measured, advantages (see Section 3.9) and t h e s e n s i t i v i t y of d e t e c t o r s (e.g.,
because o f t h e flame i o n i z a t i o n
and electron-capture d e t e c t o r s ) . Kojima ( r e f . japonica.
4 5 ) s t u d i e d t h e pungent odors
Components
i d e n t i f i e d and
p r o p y l - i s o - t h i o c y a n a t e and 3-butenyl Reshetnikova e t coatings
during
al.
setting.
(ref.
determined
from t h e h y d r o i y z a t e o f
were
ally1
Wasabia
isothiocyanate,
iso-
isothiocyanate. 46)
sampled
Compounds such
as
the
volatiles
CO,
acetaldehyde,
(b.p.
20-300°C)
acetone,
from
toluene,
97 benzene,
b u t y l alcohol,
b u t y l acetate,
isobutanol and e t h y l benzene Yere i d e n t i f led. 3 mg/m N l k l t i n e t a l . ( r e f . 47) determined
.
S e n s l t i v l t y o f method I s g l v e n as 0.05-0.1 hydrocarbons i n a i r ,
snow, t r e e bark and leaves by p l a c i n g t h e sample i n a s a t u r a t e d
sodium c h l o r i d e s o l u t i o n and h e a t i n g t o 80-90'C. o u t o f t h e c o n t a i n e r s w i t h c a r r i e r gas.
The v o l a t i l e hydrocarbons were swept
Fedchenko and Vigdergauz ( r e f . 48) showed t h e
e f f e c t o f water vapor as e l u e n t as compared t o n i t r o g e n .
C5-,
C8-,
and Cl0-acid
C,3-alkanes.
C4-.
nltriles;
Compounds s t u d i e d were t h e
Cll-
and C8-,
and C g - a l c o h o l s
C7-,
and
The HETP ( h e i g h t e q u i v a l e n t t o a t h e o r e t i c a l p l a t e ) values decreased
w i t h t h e t r a n s i t i o n from n i t r o g e n t o water vapor.
E l u t i o n t i m e s were 2.4X
longer w i t h
n itrogen. Methane,
e t h y l e n e and n i t r o u s o x i d e were
above s o i l samples u s i n g t h i s technique.
identified
using b o t h a Porapak N and a Porapak S column ( r e f . 49). iosmers up t o C column.
50).
)
i n t h e headspace vapor
The v o l a t i l e s were separated and determined V o l a t i l e f a t t y acids (plus
i n u r i n e samples were determined on a 3% F l u o r a d FC 430/Chromosorb G
5 The c a r r i e r gas was n i t r o g e n and t h e d e t e c t i o n was by flame i o n i z a t i o n ( r e f .
Headspace sampling o f t h e v o l a t i l e s over r o a s t e d c o f f e e ( r e f s .
used t o study t h e aging process.
51 and 52) was
N i t r o g e n c a r r i e r gas and flame i o n i z a t i o n and flame
p h o t o m e t r i c d e t e c t o r ( t h e l a t t e r i s s p e c l f i c f o r s u l f u r compounds) were used. V o l a t i l e m a t e r i a l s decreased more i n q u a n t i t y w i t h t i m e f o r t h e whole-roasted than for t h e ground-roasted beans.
Using t h e headspace technique,
53) were a b l e t o determine Cog i n HCI gas a t t h e 5-100 ppm l e v e l . t h e c a r r i e r and TCD was t h e means of detection.
Rath e t a l .
bean (ref.
Hydrogen gas was
V o l a t i l e s i n beer were determined by
t h e headspace technique ( r e f . 5 4 ) by means o f adding 28 g o f NaCl t o 100 m l o f beer and h e a t i n g i n a c l o s e d c o n t a i n e r t o 4 O O C .
Diketones,
high-molecular-welght
alcohols
and e s t e r s were determined using e l e c t r o n - c a p t u r e and flame i o n i z a t i o n measurements. Tarasova substances.
and
Kataeva
(ref.
55)
determined
The polymeric sample was placed i n water,
o i l added and t h e c o n t a i n e r sealed.
separated on a Apiezon L/Chromosorb W column.
as a s u r v e y o f
chlorinated
i n water
in
polymeric
sampled by s y r i n g e and
Drozd and Novak ( r e f . 56) have w r i t t e n
Various aspects o f t h e technique a r e discussed as
applicatlons.
hydrocarbons
chloride
aqueous alcohol o r sunflower
The c o n t e n t s were heated,
a review o f headspace gas a n a l y s i s . well
vinyl
The t e c h n i q u e has been used t o d e t e r m i n e
samples
(refs.
57 and 58).
Volatile
m e t a b o l i t e s from b i o l o g i c a l t i s s u e have been s t u d i e d by M a i o r i n o e t a l . They were able t o d e t e c t 2 pmoles/ml
i n b l o o d and 10 pmoles/g
in
halothane (ref.
59).
l i v e r samples.
Aromatic hydrocarbons I n gases s a t u r a t e d w l t h water vapor have a l s o been done by t h i s technique ( r e f . 60).
These same authors determined t h e KD values f o r benzene, t o l u e n e
and m-xylene between water and a i r a t temperatures r a n g i n g from 10-30°C.
Kolb e t a l .
( r e f . 52) u t i l i z e d t h e technique f o r samples i n j e c t e d o n t o c a p i l l a r y columns.
This
e l i m i n a t e d t h e need f o r i n l e t s p l i t t e r s and i n l e t pressure was r e g u l a t e d w i t h narrow bore c a p l l l a r i e s .
T h e i r system was used f o r a n a l y s i s o f f l a v o r s ,
crude o i l vapor e x t r a c t s .
water p o l l u t a n t s and
Vinyl c h l o r i d e and d l c h l o r o e t h a n e I n e t h y l e n e g l y c o l were
98 determined i n t h e headspace from sealed c o n t a i n e r s a t 30°C ( r e f . 6 1 ) .
5 5%.
volume percent w i t h a r e l a t i v e e r r o r
o f t h e method i s 5 x
The s e n s i t i v i t y Benzene, t o l u e n e
and xyiene were measured i n a i r samples c o l l e c t e d i n a c e t i c a c i d ( r e f . 62).
The a c i d
s o l u t i o n was made basic w i t h potassium hydroxide and t h e headspace vapors analyzed by 3 The standard d e v i a t i o n o f t h e technique i s 0.02-0.04 mg/m
.
gas chromatography.
N i t r o u s oxide has been determined by headspace sampling and e l e c t r o n capture d e t e c t i o n (ref.
P r e c i s i o n b e t t e r t h a n 2% was a c h i e v e d w i t h w a t e r samples > 60 m i .
63).
Long-ter? storage o f samples showed a 2 . 3 % v a r i a t i o n i n c o n c e n t r a t i o n o f t h e n i t r o u s
A study o f headspace sampling by standard a d d i t i o n f o r t h e d e t e r m i n a t i o n o f
oxide.
benzene i n water a t t h e 1-1000,g
range i n a c o n t a i n e r w i t h 50 ml o f a i r and 50 ml o f
water, showed 8-28 e r r o r a t t h e r e s p e c t i v e l e v e l s ( r e f . 6 4 ) . t o 0.02-2
ppm benzene i n t h e aqueous phase.
t h e determination of
water
These l e v e l s correspond
A r a v e r s e use o f headspace sampling was
in sincalide at
100°C
(ref.
65).
The water
determined by gas chromatography u s i n g a Porapak Q column and thermal detection.
was
conductivity
Hydrogen s u l f i d e i n heated m i l k was determined by g a s - l i q u i d
graphic headspace a n a l y s i s ( r e f . 66), also.
vapor
chromato-
The headspace sample was separated on a
p o l y t e t r a f l u o r o e t h y l e n e column o f poly(pheny1 e t h e r ) and phosphoric a c i d and detected by flame i o n i z a t i o n . The headspace technique vinegars
and alcohol i t
has been a p p l i e d t o a n a l y s i s of
beverages
(ref.
671,
monomer i n p l a s t i c packaging and beverages monochlorobenzene and dichlorobenzene)
wine
(ref.
aromas
(ref.
vinyl 68,
chloride
in
acryionitrile
69) and t r a c e o r g a n i c s (benzene,
i n HCI gas,
methylene c h l o r i d e and methylene
bromochloride i n HBr gas ( r e f . 70) and v o l a t i l e aromas from t h e gardenia flower ( r e f . 71).
Smith e t a l .
(ref.
72) converted hexafluoroacetone from i n d u s t r i a l waste water
t o f l u o r o f o r m (CHF3) f o r headspace a n a l y s i s by gas chromatography. l i n e a r f o r CHF
4.3.2.1
3
The method was
c o n c e n t r a t i o n o f 10 ppb-1000 ppm.
Headspace and/or vapor e q u i l i b r a t i o n .
Headspace a n a l y s i s i s a method
o f determining v o l a t i l e o r g a n i c components as p o l l u t a n t s i n water i n which t h e aqueous phase i s e q u i l i b r a t e d w i t h an i n e r t gas phase u s u a l l y of equal volume.
The fundamen-
t a l s o f t h i s technique have been described by M c A u i I f f e ( r e f . 35). The method may be defined as t h e e x t r a c t i o n o f components o f i n t e r e s t by a gas and t h e subsequent a n a l y s i s o f t h i s gas phase by gas chromatography.
T h i s technique
may broadly be separated i n t o two c l a s s i f i c a t i o n s :
( 1 ) The a n a l y s i s o f t h e vapor phase,
i n e q u i l i b r i u m w i t h t h e l i q u i d phase, from
a closed s t a t i c system;
( 2 ) The sparging o f t h e l i q u i d phase by an i n e r t gas f o i lowed by a n a l y s l s o f t h e gas phase.
I n t h i s c l a s s l f i c a t i o n , t h e gas phase may be trapped by a d s o r p t i o n or
condensed a t cryogenic temperatures ( r e f s . 73-77). In t h e f i r s t c l a s s i f i c a t i o n ,
t h e c o n c e n t r a t i o n s o f t h e components i n t h e gas
phase do not change appreciably unless a large sample has been withdrawn.
In the
second c l a s s i f i c a t i o n , Thus,
the
system
t h e component c o n c e n t r a t i o n s decrease c o n t i n u o u s l y w i t h time.
devlates
from e q u i l i b r i u m ;
in
fact
t h e cmponent
concentration
approaches zero a s y m p t o t i c a l l y . D i f f i c u l t i e s may a r i s e i f t h i s technique i s used improperly, and q u a n t i t a t i v e l y . cial
both q u a l i t a t i v e l y
One c o u l d n o t expect a complete q u a l i t a t i v e a n a l y s i s o f a commer-
sample by t h i s technique because many o f
present a t t h e ppm l e v e l or even ppb l e v e l .
the
sample
components
Bassette e t al.
may o n l y
be
78) s e l e c t i v e l y
(ref.
removed components from t h e sample by use o f s p e c i f i c chemical reagents.
For example,
they were a b l e t o remove ketones from t h e e q u i l i b r a t e d gas phase by r e a c t i o n w i t h acidified
hydroxylamine
Sulfur-containing
reagent
and
esters
with
alkaline
hydroxylamine
reagent.
compounds were s e l e c t i v e l y removed w i t h m e r c u r i c c h l o r i d e .
Palo
( r e f . 79) employed t h e same technique f o r q u a l i t a t i v e headspace a n a l y s i s . L i t t l e a t t e n t i o n has been g i v e n t o t h e design o f t h e headspace e q u i l i b r a t i o n equipment.
R e l i a b l e p e r f o r m a n c e o f t h e e q u i p m e n t i s one o f t h e most
One must be a b l e t o c o n t r o l
r e q u i r e m e n t s f o r q u a n t i t a t i v e headspace a n a l y s i s .
t h e o p e r a t i n g c o n d i t i o n s and be a b l e t o reproduce them.
It
headspace gas a n a l y s i s than f o r o t h e r q u a n t i t a t i v e techniques. careful
important
i s more important
for
The chemist must be
i n b o t h c o l l e c t i n g and t r a n s f e r r i n g t h e sample so .that changes do n o t occur
because o f condensation or
leakage.
Clean equipment
components are n o t present from a previous sample.
i s essential
so t h a t
This i s especially
residual
important
in
environmental s t u d i e s because o f t h e concern about c o n c e n t r a t i o n l e v e l s . Cal i b r a t i o n o f such a system can be accompl ished by separate p r e p a r a t i o n o f an a p p r o p r i a t e model
standard,
initial
or by p r i o r determination o f t h e d i s t r i b u t i o n c o n s t a n t w i t h a
analysis,
by d i r e c t
d e f i n e d l i q u i d phase c o m p o s i t i o n .
addition
of
a standard t o t h e sample a f t e r
An a l i q u o t of t h e e q u i l i b r a t e d g a s phase is
t r a n s f e r r e d t o a gas chromatograph f o r a n a l y s i s u s i n g e i t h e r a g a s - t i g h t gas-sampling v a l v e ( i n c e r t a i n circumstances).
s y r i n g e or a
The method can be a p p l i e d t o a wide
v a r i e t y o f v o l a t i l e o r g a n i c compounds which are p o l l u t a n t s i n water. i n v e s t i g a t e d ( w i t h normally v o l a t i l e compounds),
I n every case
the application of t h i s technique I s
u s u a l l y s e n s i t i v e t o l e v e l s o f 10 ppb or less i n t h e o r i g i n a l sample. A v a r i a n t o f t h e headspace gas a n a l y s i s technique has been described by Gottauf
( r e f . 80) i n which he determined t h e t r a c e v o l a t i l e s i n water samples.
The headspace
gases were concentrated by adsorption on a cooled adsorbent and losses by a d s o r p t i o n o r adsorption i n t h e o r i g i n a l sample were minimized. w i t h an R.S.D.
The l i m i t o f d e t e c t i o n was below
o f 20.05%.
The type of m a t e r i a l used i n t h e seal when sampl i n g by means o f a s y r i n g e has
el),
been shown t o i n t r o d u c e e r r o r s .
Maier
(ref.
Nursten
have
demonstrated t h e
(ref.
83) independently
because o f r u b b e r s e a l s (e.g., s i l i c o n e rubber septa.
serum b o t t l e s ) .
Davis ( r e f .
82) and G i I l i v e r and
loss o f
sample
components
S i m i l a r l o s s e s were n o t e d w i t h
Davis's ( r e f . 82) data r e v e a l e d t h a t exposure t o rubber s e a l s
f o r t h i r t y minutes decreases component c o n c e n t r a t i o n o f
hydrocarbons and aldehydes.
100 The r a t e of
d i f f u s i o n among t h e various
components i s another
q u a n t i t a t i v e d a t a by t h i s t e c h n l q u e .
source o f
for
T h i s e r r o r becomes p r o n o u n c e d when t h e
e q u i l i b r a t i o n t i m e i s s h o r t and t h e headspace volume i s l a r g e ( r e f . samp I i ng and
advantages and d I sadvantages o f
error
i n j e c t i n g w It h
a
84).
The
have
been
syringe
t r e a t e d by Binder ( r e f . 8 4 ) . The i n i t i a l r e s u l t o f t h e headspace gas a n a l y s i s because t h e m a t r i x gas i s not measured. (which i t u s u a l l y does),
t h e c a l c u l a t i o n o f t h e c o n c e n t r a t i o n f o r t h e n t h component
may not n e c e s s a r i l y be v a l i d because a partial
i s o n l y a r e l a t i v e measure
I f t h e gas c o n t a i n s more than one component linear
relationship w i l l
n o t e x l s t between
pressures and c o n c e n t r a t i o n s unless t h e s o l u t i o n s and gaseous phases both
approach
ideality.
components,
Since most
the t o t a l
pressure
headspace gases a r e m i x t u r e s (vapor
pressure)
i s the
of
sum o f
several the
volatile
partial
vapor
pressures:
p
t
= p t p t Pj t 1 2
... t Pn = X1PY
.+
x2P'I
.+
. a .
.+ XnPZ
(4.10)
where Pt = t o t a l vapor pressure o f system; P, e t c . = p a r t i a l pressure o f each component; Py e t c . = vapor pressures o f t h e pure components; x1 e t c . = mole f r a c t i o n s o f each component.
Using eqn. 4.10,
one assumes t h a t t h e p a r t i a l pressures are s u f f i c i e n t l y small
so t h a t they may be i d e n t i f i e d w i t h D a l t o n ' s p a r t i a l pressures:
P
= (n
T)/V
(4.11)
T h i s imp i e s t h a t t h e number o f moles nl, chemical a n a l y s i s o f t h e vapor volume, V.
(
)
n2,
......nn
a r e e a s i l y determined from the
Thus, one must consider two s i t u a t i o n s :
As t h e pressure o f t h e headspace gas increases, c o m p i i c a t i o n s a r i s e because
o f d e v i a t i o n s from t h e i d e a l gas laws. ( 2 ) Total pressure ( P t ) dependence on the sum of t h e p a r t i a l pressures v a r i e s from system t o system,
and i t i s m r e accurate t o i n c o r p o r a t e a c t i v i t y c o e f f i c i e n t s
y
i n eqn. 4.10. P =',X1Py t
t y2X2P20 t
...... t Yn x nPnO
Because of t h e v a r i e t y o f
(4.12)
samples encountered
i n headspace gas a n a l y s i s ,
a
number o f s i t u a t i o n s may present themselves.
( A ) The components o f s i m i l a r t y p e molecules).
the
sample could
show no mutual
Linear dependence o f t h e t o t a l
interaction
(i.e.,
pressure w i t h t h e p a r t i a l
101 pressures w i l I f o l l o w , as shown i n eqn. 4.10. y,
I n t h i s case, t h e a c t i v i t y c o e f f i c i e n t s
w i l l equal 1 .
( B ) The i n t e r a c t i o n s between l i k e molecules are g r e a t e r than t h e i n t e r a c t i o n s between u n l i k e molecules i n t h e vapor phase.
The l i k e molecules tend t o d i s p l a c e each
o t h e r from the m i x t u r e and increase t h e i r p a r t i a l pressures. t i v e d e v i a t i o n from R a o u l t ' s
law.
This r e s u l t s i n a posi-
I t a l s o means a l i q u i d phase o f these components
w i l I b o i i a t a temperature lower than e i t h e r o f t h e pure l i q u i d s . some o f t h e molecules have p o l a r groups and some o f groups (e.g.,
a l c o h o l s and hydrocarbons).
a c t i v i t y coefficients, (C)
y,
T h i s i s p r e d i c t e d by eqn.
4.12,
when t h e
are not equal t o 1.
The reverse o f
u n l i k e molecules
T h i s occurs when
t h e molecules have non-polar
s i t u a t i o n B could
i s g r e a t e r than
the
occur
interaction
(i.e.,
the
between
I n t e r a c t i o n between
l i k e molecules).
This
decreases t h e p a r t i a l vapor pressures from t h e values f o r an ideal m i x t u r e and causes negative d e v i a t i o n s from R a o u l t ' s components w i l l
boil
at
law.
The l i q u i d phase o f t h e m i x t u r e s o f these
a temperature higher
than e i t h e r o f
t h e pure components.
Systems l i k e t h i s occur when t h e a t t r a c t i v e f o r c e s a r e o f e l e c t r o s t a t i c o r i g i n ,
i.e.,
t h e molecules possess permanent o r induced d i p o l e s which can lead t o t h e f o r m a t i o n o f hydrogen bonds or o t h e r l a b i l e bonds between t h e molecules.
( D ) A combination o f B and C,
i.e.,
b o t h p o s i t i v e and n e g a t i v e d e v i a t i o n s
in
t h e gas phase. S i t u a t i o n s 6, C and D w i l l ,
i n many cases,
show p a r t i a l pressures n o t v a r y i n g
l i n e a r l y w i t h c o n c e n t r a t i o n o r which are completely
independent o f c o n c e n t r a t i o n i n
Headspace gas a n a l y s i s under these c o n d i t i o n s w i l l n o t
t h e high-concentration ranges.
g i v e q u a n t i t a t i v e r e s u l t s or may even g i v e t h e same r e s u l t f o r d i f f e r e n t concentraThe systems described i n B, C and D can be minimized i f t h e experimental work
tions.
i s performed a t h i g h d i l u t i o n ( r e g i o n o f shown t h a t
headspace gas analysis; i s linear. ketones,
i n fact,
alcohols,
i n water
at
low
concentrations
using
t h e r e l a t i o n s h i p between peak area and c o n c e n t r a f i o n
Ozeris and Bassette ( r e f .
aldehydes,
Hachenberg ( r e f . 8 5 ) has
ideal m i x t u r e s ) .
a c r y l o n i t r i l e may be determined
86) demonstrated t h a t ,
at
low c o n c e n t r a t i o n s ,
d i e t h y l s u l f i d e and e s t e r s show a l i n e a r r e l a t i o n s h i p
between peak h e i g h t and c o n c e n t r a t i o n (0.01-10
ppm l e v e l s I n water).
Sometimes t h e c o n c e n t r a t i o n s of t h e components of i n t e r e s t a r e a t l e v e l s where the detector signal
i s o f t h e same order o f magnitude as t h e noise.
one simply enriches t h e components i n t h e headspace gas. t h e headspace gas i s t o increase t h e
I f t h i s occurs,
The e a s i e s t way t o e n r i c h
i o n i c s t r e n g t h o f t h e , aqueous s o l u t i o n .
a d d i t i o n o f h i g h l y s o l u b l e s a l t s w i l l do t h i s very c o n v e n i e n t l y .
s u l f a t e ( r e f . 87). ammonium s u l f a t e or sodium c h l o r i d e ( r e f . 87) have been used. c a l c i u m carbonate (which I s not t h a t s o l u b l e
I n water)
The
S a l t s such as sodium Even
has been used s u c c e s s f u l l y
( r e f . 88). The b i g advantage o f headspace gas a n a l y s i s by gas chromatography s o l v e n t peak i s e l i m i n a t e d .
i s t h a t the
Combining t h i s advantage w i t h t h e enrichment technique
p e r m i t s one t o do an a n a l y s i s w i t h g r e a t l y reduced d e t e c t i o n l i m i t s .
T h i s advantage
a p p l i e s e q u a l l y t o systems where one i s d e a l i n g w i t h nonaqueous s o l v e n t s ( r e f . 8 8 ) . The d i s t r i b u t i o n contant of a s o l u t e I n headspace gas a n a l y s i s i s r e a l l y t h e inverse o f Henry's law;
however, t h e chemist i s more concerned w i t h t h e mass balance
o f t h e s o l u t e between t h e two phases.
he f i n d s i t m r e convenient t o d e f i n e t h e
Thus,
d i s t r l b u t i o n constant I n terms o f t h e r a t i o o f t h e e q u i l i b r i u m c o n c e n t r a t i o n s o f t h e s o l u t e i n t h e condensed and gaseous phases. KD = (WL/VL)/(WG/VG)
(4.13)
where W
and WG = mass o f t h e s o l u t e I n t h e condensed and gaseous phases, L t l v e l y , and VL and VG = volumes o f these two phases.
respec-
I t i s f a i r l y easy t o o b t a i n q u a n t i t a t i v e data i f one has a one-phase
system.
However,
i n headspace gas a n a l y s i s t h e s o l u t e component
i s d i s t r i b u t e d between two
phases.
Thus one must know t h e magnitude o f t h e mass d i s t r i b u t i o n between t h e two
phases.
To o b t a i n t h i s i n f o r m a t i o n a l l one needs i s t h e t o t a l amount o f t h e s o l u t e
i n t h e system and t h e amount of t h e s o l u t e which has been equi I i b r a t e d i n t o t h e gas phase.
W
n
= c
Thus t h e t o t a l amount o f t h e solute, Wn,
nG
(K V
D L
+
can be expressed as:
VG)
(4.14)
where cnG = WnG/VG-
By q u a n t i t a t i v e gas chromatography one can o b t a l n a value f o r c of VL and VG are known and i f one knows KD, t h e v a l u e o f Wn p r o b l e m Is t h a t one v e r y seldom knows t h e v a l u e o f
The values nG' Is e a s i l y c a l c u l a t e d . The
KD.
T h i s p r o b l e m may be
circumvented i n several ways ( r e f . 5 6 ) .
( 1 ) Use experimental c o n d i t i o n s i n which t h e value of KD i s e s s e n t i a l l y equal t o zero.
This may be achieved by working a t e l e v a t e d temperature.
I n t h i s case, eqn.
4 . 1 4 becomes:
wn
=
(4.15)
CnGVG'
Using q u a n t i t a t i v e gas chromatography, method i s very seldom used;
i t i s easy t o determine t h e value o f cnG.
( 2 ) Use a standard system s o l u t i o n , components of t h e unknown sample determined.
The
preference i s given t o ambient c o n d i t i o n s .
plus
i.e.,
-
a sample which c o n t a i n s a l l
the
a known amount o f t h e sample component being
I f one keeps VL and VG t h e same f o r both samples, t h e KD f o r both samples
has t o be t h e same.
T h i s being t h e case,
because i t . i s common t o bcth systems.
t h e f a c t o r (KDVL + V G ) I f Wn*
I s the t o t a l
w i l l be e l i m i n a t e d
amount o f
the solute
103 i n i t s gas
component i n t h e standard system s o l u t i o n and cnG* i s i t s c o n c e n t r a t i o n phase one o b t a i n s :
w * = c nG*(KDVL
+ VG)
(4.14A)
VG)*
(4.148)
and
Wn = c
nG
(K'V
D L
+
D i v i d i n g eqn. 4.148 by eqn. 4.14A:
W"
=
(4.16)
Wn*CnG/CnG*'
Determining c value f o r Wn.
and cnG* under t h e same gas chromatographic c o n d i t i o n s g i v e s us t h e
nG
T h i s method i s n o t used because
it
i s almost
i m p o s s i b l e t o make a
standard system s o l u t i o n which i s t h e same as t h e unknown.
( 3 ) Use o f t h e standard a d d i t i o n method.
The assumptions made h e r e a r e t h a t
t h e added amount o f t h e component t o be determined i n v o l v e s l i t t l e o r no change i n t h e values o f VG and V L change o f change.
(i.e..
the r a t i o of VL/VG).
t h e thermodynamic
properties of
This,
i n turn,
causes l i t t l e or no
KD does n o t
t h e s o l u t i o n and t h e r e f o r e
The main c o n s t r a i n t p l a c e d on t h i s method i s t h a t t h e sample,
a f t e r t h e a d d i t i o n o f t h e known amount o f component n, identical conditions.
b e f o r e and
must b y a n a l y z e d u n d e r
The amount o f added component must be g r e a t e r
than t h e
e s t i m a t e d c o n c e n t r a t i o n i n t h e unknown ( a minimum o f 2-3 t i m e s g r e a t e r ) .
F o l l o w i n g these c o n d i t i o n s t h e q u a n t i t y Wn may be c a l c u l a t e d :
wn
= (WS
-
WOn)/((COnG/CnG)
-
1)
(4.17)
where Ws = mass o f added standard;
Won = e s t i m a t e d amount o f component n b e f o r e standard a d d i t i o n ; conG = c o n c e n t r a t i o n i n gas phase a f t e r standard a d d i t i o n .
T h i s t h i r d method o f a n a l y s i s i s t h e one recommended f o r t h e a n a l y s i s o f aqueous waste e f f l u e n t s f o r t h e presence o f p r i o r i t y p o l l u t a n t s . There are a number o f
good p u b l i c a t i o n s
concerning
headspace
analysis:
a
review w r i t t e n by Drozd and Novak ( r e f . 561, two books ( r e f s . 89 and 90). and a r e c e n t paper
describing
i t s applications t o the analysis of
water e f f l u e n t s ( r e f . 91).
p r i o r i t y pollutants
i n waste
Any o f these r e f e r e n c e s w i l l f u r n i s h t h e needed background
f o r someone u s i n g t h e technique f o r t h e f i r s t t i m e .
M c A u l i f f e ( r e f . 35) p u b l i s h e d a method o f headspace gas a n a l y s i s which i s more
s p e c i f i c a l l y t i t l e d "vapor e q u i l i b r a t i o n analysis".
H i s o r i g i n a l work was concerned
w i t h hydrocarbons i n water b u t has now been extended t o many o t h e r t y p e s of compounds. The technique involves e q u i l i b r a t i n g equal volumes o f an aqueous s o l u t i o n and an i n e r t gas ( u s u a l l y helium o r n i t r o g e n )
A t t h i s p o i n t i n the
i n a l a r g e g l a s s syringe.
procedure t h e chemist has two o p t i o n s : ( 1 ) The e n t i r e gas phase may be i n j e c t e d i n t o t h e sample loop o f a gas sampling
valve m u n t e d on t h e gas chromatograph. into
the
syringe.
The
procedure
A second equal volume o f
is
repeated
several
i n e r t gas i s drawn
times.
The
original
concentration o f components i n t h e sample can be c a l c u l a t e d from t h e dependence o f c o n c e n t r a t i o n i n t h e headspace on t h e s e r i a l number o f e x t r a c t i o n s performed.
( 2 ) A f t e r f i l l i n g t h e s y r i n g e w l t h equal volumes o f aqueous sample and i n e r t gas ( c l e a n a i r may a l s o be used), t h e s y r i n g e may be capped w i t h a rubber septum and a l i q u o t volumes removed by means o f another smaller smaller-volume the
sample
s y r i n g e may be i n j e c t e d
injection
port.
syringe.
The c o n t e n t o f t h i s
i n t o t h e chromatograph through t h e septum of
R e p l i c a t e samples may
be
injected
without
seriously
a f f e c t i n g t h e q u a n t i t a t i v e r e s u l t s o f t h e method. The method o f
standard
e q u i l i b r a t i o n technique.
a d d i t i o n may a l s o be used w i t h t h i s
s y r i n g e vapor
T h i s has been demonstrated r e p e a t e d l y ( r e f s . 64, 92 and 9 3 ) .
One removes a volume VG o f t h e headspace gas from t h e e q u i l i b r a t e d system and i n j e c t s The component o f i n t e r e s t w i I i have a peak area A
i t i n t o t h e gas chromatograph.
.
A
known mass W s i s then introduced i n t o t h e e q u i l i b r a t e d s y r i n g e system and allowed t o re-equilibrate.
A second volume V o G
i s t h e n removed and i n j e c t e d i n t o t h e gas
chromatograph g i v i n g a peak area A',.
The mass o f t h e component
in the original
sample may then be c a l c u l a t e d :
Wn = ( W s
- Won)/((AonVG/AnVoG)
Using t h i s
-
technique,
aromatic hydrocarbons (0.001
(4.18)
1)
a hydrophilic
-
solute
(1-100
ppm)
and
aliphatic
and
20 ppm) have been determined w i t h r e l a t i v e e r r o r s o f
approxlmately 20-22$ and 10-12%, r e s p e c t i v e l y ( r e f . 9 4 ) . C u r r e n t l y t h e method developed by B e l l a r and Lichtenberg ( r e f s . 95-95) has been w i d e l y applied f o r s i m l l a r analyses. trap",
T h e i r method,
d i f f e r s from t h e v a p o r - e q u i l i b r a t i o n
requires s i g n i f i c a n t l y
more e l a b o r a t e
trapping e f f i c i e n c y of
each component o f
commonly designated
method.
equipment
and
a reliance
concern o r a c a r e f u l
t r a p p l n g e f f i c i e n c y and p r e c i s e d u p l i c a t i o n o f sample processing. v a p o r - e q u i l i b r a t i o n a n a l y s i s i s f a r lower,
"purge and
The p u r g e and t r a p method upon
either
delineation of
100% the
Equipment c o s t f o r
and i t s use i s c o n s i d e r a b l y s i m p l e r .
In a
number o f cases t h e purge and t r a p system may be more s e n s i t i v e because t h e t o t a l v o l a t i l e organlc content of
an aqueous sample (5-60 m l )
instrument f o r a s i n g l e a n a l y s i s . e q u i l i b r a t i o n analysis.
However,
can be t r a n s f e r r e d t o t h e
T h i s i s g e n e r a l l y n o t t r u e i n t h e case o f vapor r e p l i c a t e analyses o f t h e same sample a r e much more
105 r e a d i l y o b t a i n e d b y vapor e q u i l i b r a t i o n . transfer
of
t h e sample
i t s original
from
extreme care i s exercised w i t h t h i s step,
The p u r g e and t r a p s y s t e m r e q u i r e s a c o n t a i n e r t o t h e purge t h e most v o l a t i l e
and/or
t h e o r g a n i c contaminants can be l o s t i n unknown p r o p o r t i o n .
system.
Unless
least soluble of
Alternatively,
even
If
t h e purge system c o n t a i n e r i s used t o o b t a i n t h e sample ( n o t common p r a c t i c e because o f t h e l i m i t e d sample s i z e ) ,
i t must g e n e r a l l y be opened i n o r d e r t o mount it i n t h e
instrument system, w i t h p o t e n t i a l attendant vapor losses. One m a n u f a c t u r e r ( r e f s . technique
of
analysis."
98-101)
Volatile
uses what
organic
i s d e s i g n a t e d as t h e "dynamic
components
in
a
water
sample
are
continuously purged by a gas and then q u a n t i t a t i v e l y t r a n s f e r r e d t o an a d s o r p t l o n t r a p where t h e y a r e l a t e r t h e r m a l l y desorbed and b a c k f l u s h e d o n t o an a n a l y t i c a l gas chromatographic column. multi-sample
unit
Another manufacturer ( r e f s .
i n which
the
detectors
102-105) has o f f e r e d a dedicated,
and c o n t r o l
units
samples can be accommodated w i t h f u l l y automatic o p e r a t i o n . of flame-ionization w i r e detector,
detector,
phosphorus d e t e c t o r ,
i n a d d i t i o n t o column-effluent
a r e modular.
electron-capture
d e t e c t o r o r hot-
s p l i t t i n g and dual-detector
operation.
The u n i t w i I I accept i i q u i d or s o l i d samples and can be used f o r alcohol residual
monomers
i n polymers,
lndustrial
hygiene
(e.g.,
Thirty
The u n i t o f f e r s a c h o i c e
vinyl
chloride
f o r e n s i c work (amphetamines i n u r i n e ) and environmental s t u d i e s (e.g.,
i n blood, in air),
hydrocarbons i n
water). With v a p o r - e q u i l i b r a t i o n a n a l y s i s i t i s p o s s i b l e t o t a k e t h e sample i n t h e same c o n t a i n e r u l t i m a t e l y used f o r i t s a n a l y s i s . once obtained,
t h e sample
i s never
T h i s c o n t a i n e r i s septum-sealed so t h a t ,
again opened,
even d u r i n g t h e a n a l y s i s .
losses are precluded as long as t h e septum m a t e r i a l components o f
interest.
equilibration
analysis
A number of such septum m a t e r i a l s a r e a v a i l a b l e .
method
has
shown
distinctive
Vapor
i s not permeable t o t h e sample
superiority
The vapor
because
of
this
s i m p l i f i e d sampling i n t h e a n a l y s i s o f chemical process waste l i n e s which a r e o b t a i n e d a t elevated temperatures. Residual acetone.and
vinyl
chloride
injected directly
in
poly(viny1
c h l o r i d e ) ( P V C ) may
be
extracted
by
I n t o t h e gas chromatograph or a sample o f PVC may be
heated (sealed c o n t a i n e r ) w i t h a small amount of d i e t h y l e t h e r and a headspace sample taken
(ref.
Cowen e t a l .
106). (ref.
Both techniques
are consid ered good approaches t o t h e problem.
107) r e p o r t e d t h e c o n s t r u c t i o n o f a device t o a i d i n septumiess
i n j e c t i o n s o f headspace gas and compared i t t o t h e s y r i n g e i n j e c t i o n technique. I n a t y p i c a l analysis, 50-mi
using McAuliffe's
technique ( r e f .
35). one would use a
glass s y r i n g e c o n t a i n i n g 25 m l o f t h e water sample and 25 ml o f an i n e r t gas.
A f t e r t h e two phases have e q u i l i b r a t e d ,
one may use t h e e n t i r e gas phase or an a l i q u o t
taken w i t h a smaller s y r i n g e (see above).
Unless one knows t h e v a l u e o f t h e d i s t r i -
b u t i o n constant KD, t h e data w i l l be more q u a l i t a t i v e than q u a n t i t a t i v e . water phase i s not a problem;
Loss o f any
t h e second gas e q u i l i b r a t i o n i s c a r r i e d through w i t h a
gas volume equal t o t h e decreased l i q u i d volume.
The c r i t i c a l parameter i s c o n t r o l o f
106 temperature;
t h i s should remain constant from one equi I i b r a t l o n t o t h e n e x t .
Determination of t h e d i s t r i b u t i o n constant KD can e a s i l y be performed. ( A ) E q u i l i b r a t e equal volumes o f i n e r t gas and water sample I n a 50-ml syringe.
(8) I n j e c t a known volume of t h e gas phase i n t o t h e gas chromatograph and measure e i t h e r t h e peak a r e a o r t h e peak h e i g h t and r e l a t e t h i s measurement t o concentration.
(C) Remove any remaining gas phase i n t h e 50-ml s y r i n g e . ( D ) E q u l l l b r a t e t h e water phase w i t h several a d d i t i o n a l equal volumes of i n e r t gas and repeat steps B and C w i t h each.
(E)
it can be shown ( r e f . 35) t h a t t h e f o l l o w i n g equation w i l l r e l a t e KD t o
c o n c e n t r a t i o n i n t h e water phase: log ( ( X I
g n
= -nlog(KD
+
1)
+
log KD(Xll
(4.19)
where ( ( X )
) = q u a n t i t y of component X i n t h e gas phase a f t e r n e q u i l i b r a t i o n s , g n ( X I , = i n i t i a l q u a n t i t y o f X i n t h e water phase.
and
A log p l o t of area o r peak h e i g h t ( i n terms o f c o n c e n t r a t i o n ) versus t h e number of e q u i l i b r a t i o n s . w i l l produce a s t r a i g h t l i n e having a slope o f -log(KD intercept of
l o g KD(X)l.
Having t h i s p l o t ,
A r e p r e s e n t a t i o n of
such a p l o t
+
11,
and an
i s shown i n Flg.
4.2.
one can s e l e c t any two adjacent gas phase c o n c e n t r a t i o n p o l n t s ,
d i v i d e t h e smaller value i n t o t h e l a r g e r value and s u b t r a c t one from t h e q u o t i e n t t o One then d i v i d e s t h e i n t e r c e p t log KD(X)l
o b t a i n t h e numerical value o f log KD.
by
1000 800
-
sz P
0
604 0 1 0 1
1 2
1 3
1 4
1 5
1 6
1 7
8
I
9
:
EQUILIBRATION NUMBER F i g . 4.2 P a r t i t i o n i n g of a s o l u t e between equal volumes o f H20 and an I n e r t gas (e.g., hei ium)
107 l o g K and o b t a i n s ( X I l , D o r l g i n a l water sample.
t h e c o n c e n t r a t i o n o f t h e component o f
Interest in the
I n a d d i t i o n t o t h e ease o f o b t a i n i n g t h e numerical value o f KD,
as described
above, t h i s technique has two o t h e r o u t s t a n d i n g f e a t u r e s . ( 1 ) Most enfironmental water samples need o n l y be equi i l b r a t e d two times.
The
f i n a l data w i l l n o t be as accurate as a m u l t i - p o i n t p l o t b u t w l i l have a h i g h degree I f two equi I i b r a t l o n s are performed,
o f accuracy. flrst
equilibration
((X)
M u l t i p l y t h i s quotient, Knowing t h e KD, I n t e r c e p t by K
Q,
d i v i d e t h e c o n c e n t r a t i o n from t h e
second e q u i l i b r a t i o n ( ( X ) 1 g l 9 2' by t h e f i r s t c o n c e n t r a t i o n t o o b t a i n t h e i n t e r c e p t value.
1
by
concentration
(previous analysls of
from
samples
from t h i s
system) one d i v i d e s t h e
D t o o b t a i n t h e c o n c e n t r a t i o n of t h e component i n t h e water sample.
(4.20) (4.21)
(4.22)
( 2 ) I f t h e water samples come from a g i v e n l o c a t i o n , which i s being monitored, (i.e.,
i f one has a llconstantll
m a t r i x composition),
t h e KD v a l u e need be checked
p e r i o d i c a l l y ( i t should be c o n s t a n t ) and each sample can be e q u i l i b r a t e d o n l y once. One may then 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 o f X i n t h e i n i t i a l sample by:
(4.23) The q u a n t i t y o f organic m a t e r i a l found i n t h e vapor four v a r i a b l e s : ionic strength.
( a ) concentration; McAuliffe ( r e f .
(b) partial
pressure;
phase
i s dependent upon
( c ) temperature;
and ( d )
108) presented t h e r e s u l t s of t h e e f f e c t s o f these
v a r i a b l e s a t a symposium on environmental a n a l y s i s .
The r e s u l t s o f h i s study showed:
( I ) a decrease i n s o l u b i l i t y ( i n c r e a s e i n q u a n t i t y found i n gas phase) o f s i x t o seven orders o f magnitude as t h e n-alkane hydrocarbons ( C 6
- CZ4)
pressure;
(3)
and
( 2 ) aromatic
i s changed from methane t o dodecane;
showed a s i m i l a r decrease i n s o l u b i l i t y or increase i n p a r t i a l
aromatic
hydrocarbons
are
cycloalkanes w i t h t h e same number o f atoms (e.g.,
mre
soluble
than
n-alkanes
or
benzene > cyclohexane > hexane).
The method o f vapor e q u i l i b r a t i o n has been shown t o have h i g h p r e c i s i o n ( r e f .
35) provided one c o n t r o l s t h e gas:water volumes and temperature ( b o t h remain c o n s t a n t throughout
replicate
measurements).
standards,
McAul i f f e
obtained
Using
standard
hexane,
deviation
cyclohexane of
20.78,
and
+0.8$
toluene and
as
20.58,
respectively. This method i s not r e s t r i c t e d t o systems where t h e gas:water 1:l.
i t has been shown ( r e f .
(sample) r a t i o i s
108) t h a t an increase i n t h e gas:water
r a t l o glves a
108 corresponding percentage Increase i n t r a n s f e r o f t h e i n d i v i d u a l gas phase.
Alkanes,
hydrocarbons t o t h e
alkenes and cycloalkanes show a decrease i n c o n c e n t r a t i o n per
u n i t volume o f gas phase whereas aromatic hydrocarbons g i v e e s s e n t i a l l y a constant r a t i o ranges o f 1 : l O
c o n c e n t r a t i o n per u n i t volume o f gas phase over t h e gas:water 1O:l.
One f i n a l comment:
and
Although t h e hydrocarbon classes p a r t i t i o n t o almost t h e
same extent, they a l l demonstrate an increase i n p a r t i t i o n i n g t o t h e gas phase w i t h an increase i n molecular weight.
One would expect t h i s t r e n d because water s o l u t i l i t i e s
( A s o l u b i l i t i e s ) decrease more r a p i d l y than vapor pressures increase ( b P i ) .
4.3.2.1.1
laboratory-prepared
I t i s the authors' opinions t h a t
standards are easy t o prepare and t h u s p r e f e r a b l e t o o t h e r o p t i o n s
where c a r e i s p r o p e r l y e x e r c i s e d . presented here.
L e t us describe t h e prepara-
P r e p a r a t i o n o f gas standard mixtures.
t i o n o f a gas standard f o r these types o f analyses.
I t i s f o r t h i s reason t h a t t h e d e t a i l s a r e
One should use a p p r o p r i a t e s a f e t y precautions f o r h a n d l i n g compressed
gases and c y l i n d e r s (Chapter 7).
For 1000 ppm standard gas mixture, one takes 100 m l
o f an i n e r t gas ( h e l i u m or n i t r o g e n ) i n a standard 100-ml c o n t a i n some 2-mn g l a s s beads (6-8 beads) f o r mlxing.
s y r i n g e which a l s o should
T h i s 100-ml s y r i n g e i s capped
i m m e d i a t e l y w i t h a r e d r u b b e r septum cap o v e r a n e e d l e hub.
A lecture b o t t l e
c o n t a i n i n g t h e pure standard gas(es) has e i t h e r a commercial pressure-reducing system o r a standard l e c t u r e - b o t t l e valve added.
valve
The l e c t u r e - b o t t l e system w i t h t h e
added valve o r pressure reducer i s f i t t e d w i t h a septum seal a t t h e e x i t end. valve system(s1 between t h e e x i t and t h e l e c t u r e - b o t t l e
A l l the
v a l v e a r e opened and t h e en-
closed volume i s evacuated by means o f a l a r g e standard g l a s s s y r i n g e by i n s e r t i n g t h e syringe needle ( w i t h t h e s y r i n g e plunger a l l t h e way down i n t h e s y r i n g e b a r r e l ) .
The
i n t e r n a l volume or o f t h e o p e r a t o r ' s
plunger i s p u l l e d back t o t h e I i m l t e i t h e r o f
a b i l i t y t o withstand t h e atmospheric pressure o p p o s i t i o n .
I f t h e s y r i n g e chosen f o r
t h i s purpose i s t o o smal I, t h i s procedure should be repeated unt i I an e v i d e n t vacuum i s contained i n t h e i n t e r i o r space o f concern.
The a u x i l i a r y v a l v e i s t h e n c l o s e d and
t h e main tank v a l v e i s opened long enough t o f i l l t h e space between t h e two valves and then
imnediately closed.
I n s e r t a standard
glass
mounted septum and then open t h e a u x i l i a r y valve. 'ihould a l l o w a 5-
t o 10-ml
syringe
carefully
through
the
The l i m i t i n g o f t h e volume segments
s y r i n g e t o absorb a l l
t h e gas expansion which r e s u l t s
without exceeding e l t h e r t h e s y r i n g e c a p a c i t y o r t h e o p e r a t o r ' s a b i l i t y t o c o n t r o l t h e s y r i n g e plunger.
Close t h e a u x i l l a r y valve, withdraw t h e s y r i n g e and i t s contents and
discharge t o an adequately v e n t i l a t e d system.
Any r e s i d u a l pressure I n t h e space
between t h e a u x i l i a r y v a l v e and t h e septum should be r e l i e v e d by again i n s e r t i n g t h e s y r i n g e and withdrawing gas u n t i l an e v i d e n t vacuum e x i s t s w i t h i n t h e a c t i v e space. T h i s e n t i r e process should be repeated a t l e a s t t h r e e times t o minimize t h e d i l u t i o n of pure gas w i t h a i r which was o r i g i n a l l y contained i n t h e system and t o avoid bleedi n g unreasonable q u a n t i t i e s o f p o t e n t i a l l y t o x i c gas i n t o t h e l a b o r a t o r y atmosphere. F i n a l l y , t h e l a s t sequence i n v o l v i n g opening o f t h e second valve should be done w i t h
109 an empty s y r i n g e needle through t h e septum t o a c t as a f i n a l purge. t h e empty needle should be withdrawn and t h e a u x l l i a r y v a l v e closed. involves f i r s t , opening t h e main t a n k v a l v e and c l o s i n g it;
Following this, The l a s t step
second, opening t h e aux-
i l i a r y v a l v e and c l o s i n g it, removing 0.2 t o 0.3 m l o f t h e contained gas i n t o a lockable v a l v e s y r i n g e such as t h e Pressure-Lok t h e s y r i n g e valve.
Series A-2
syringe,
f o l l o w e d by c l o s i n g
The removed volume should be discharged t o t h e v e n t i l a t i o n system
w i t h opening o f t h e s y r i n g e v a l v e which should be immediately closed. again i n s e r t e d through t h e septum and 0.2-0.3 s y r i n g e v a l v e closed.
The s y r i n g e i s
ml, t r a n s f e r r e d t o t h e syringe,
The s y r i n g e plunger should be c o l l a p s e d t o t h e 0.1-ml
excess pressure r e l i e v e d t o t h i s p o l n t .
and t h e mark and
To assure t h a t an excess pressure e x i s t s , t h e
needle t i p should be placed below a l i q u i d surface t o a l l o w f o r v i s u a l o b s e r v a t i o n o f t h e r e l e a s e o f t h e gas. r e l i e v i n g t h e pressure.
The s y r i n g e v a l v e s h o u l d be i m m e d i a t e l y c l o s e d a f t e r
The needle o f t h i s s y r i n g e then should be placed through t h e
s y r i n g e cap on t h e 100-ml syringe.
i n d i v i d u a l gas. (I-ml
s y r i n g e and t h e 0.1-ml
I f gas m i x t u r e s a r e d e s i r e d ,
volume t r a n s f e r r e d t o t h e
larger
t h i s p r o c e s s must be r e p e a t e d w i t h each
Lower e r r o r w i l l r e s u l t i f one prepares a 1000-ppm standard m i x t u r e
pure standard gas + 99-ml o f m a t r i x gas) and subsequently removes 10-ml
c a r e f u l l y mixed 1 % standard and t r a n s f e r s t h i s t o a second 100-ml
of the
syringe containing
90-ml o f clean m a t r i x gas.
4.3.2.1.2
Error involved when p r e p a r i n g a b i n a r y gas m i x t u r e .
One may c a l c u l -
a t e t h e ppm o f a standard gas i n a d i l u e n t gas ( m a t r i x gas) by t h e f o l l o w i n g equation:
(4.24)
where Vs term
= volume o f standard gas and VD = volume o f
i n t h e denominator
diluent
may be neglected when p r e p a r i n g c o n c e n t r a t i o n s
because t h e c o n t r i b u t i o n o f Vs t o t o t a l volume i s i n s i g n i f i c a n t . r e p r e s e n t a t i v e data f o r t h e p r e p a r a t i o n of gas standards.
The Vs
( m a t r i x ) gas.
Table 4.3
5
5000 ppm l i s t s some
Examination o f t h e data i n
Table 4.3 demonstrates t h e f a c t t h a t any e r r o r involved i n u s i n g a 100-ml s y r i n g e f o r d i l u e n t ( m a t r i x ) gas and a 1-5-ml
4.3.2.2
s y r i n g e f o r t h e s o l u t e standard gas i s v e r y small.
Purging, sparging and/or vapor s t r i p p i n g .
I f t h e o r g a n i c components o f
a water sample are v o l a t i l e or can be v o l a t i l i z e d , one may analyze t h e r e s u l t i n g vapor w i t h a h i g h degree o f
sensitivity.
The t h r e e terms
s t r i p p i n g e s s e n t i a l l y mean t h e same t h i n g ,
i.e.,
purging,
sparging
and vapor
a technique wherein an i n e r t gas i s
used t o evacuate or f r e e organic components by means o f a g i t a t i o n o f t h e sample.
What
i s d i f f e r e n t among t h e t h r e e techniques i s how it i s performed and how t h e equipment i s p h y s i c a l l y set-up.
Purging o f a water sample u s u a l l y i m p l i e s a continuous f l o w o f
110 TABLE 4.3 C o n t r i b u t i o n o f V 4 t e r m i n denominator of Eqn. 4 . 2 4
Accounting f o r
V,
+
V
Neglecting
term
Relative error ($)
Vs term
(PPm)
(PPm)
1
1.000001
Io
-~ -~
10
10.0001
1o
100
100.01
1 o-2
1000
1001.0
1 0-1
5000
5025.0
0.5
Relative error = ((exact value
-
approximate v a l u e ) / e x a c t v a l u e ) x 100.
an i n e r t gas through t h e sample and t h e passing o f t h e v o l a t i l e s t h r o u g h a t r a p p i n g tube wherein t h e v o l a t i l e components a r e adsorbed.
Sparging o f
a solution
a g i t a t i n g t h e s o l u t i o n w i t h an i n e r t gas b y means o f a sparger (e.g.,
implies
a f r i t t e d disc)
charcoal)
e i t h e r by a d s o r p t i o n on a s o l i d adsorbent (Tenax GC or or f r e e z i n g - o u t t h e v o l a t l l e s i n a t r a p submerged i n d r y i c e acetone. l i q u i d
nitrogen,
etc.
and c o l l e c t i n g v o l a t i l e s
Vapor s t r i p p i n g i s an a l l - i n c l u s i v e t e r m which c o u l d r e f e r t o e i t h e r
technique. I f t h e v o l a t l l e s a r e adsorbed on a s o l i d , i n t o a gas chromatograph.
t h e y may be desorbed and b a c k f l u s h e d
I f t h e v o l a t i l e s have been condensed i n a c o o l e d t r a p ,
f i n a l sample w i l l c o n t a i n a c e r t a i n q u a n t i t y o f water, gas chromatographic a n a l y s i s . t r a p w i t h a d e s i c c a n t tube. b u t c r e a t e s another,
i.e.,
the
which may i n t e r f e r e w i t h t h e
T h i s problem may be minimized by p r e c e d i n g t h e c o o l e d The presence o f t h e d e s i c c a n t tube e l i m i n a t e s one problem
some of t h e v o l a t i l e s a r e adsorbed on t h e d e s i c c a n t .
The technique of p u r g i n g a s o l u t i o n o f
i t s v o l a t i l e components and t r a p p i n g
them i s commonly r e f e r r e d t o as t h e "purge and t r a p " method o f s e p a r a t i o n . i s c r e d i t e d t o B e l l a r and L i c h t e n b e r g ( r e f s . 95-97 and 109).
The U.S.
The method
EPA has adapted
t h i s s e p a r a t i o n t e c h n i q u e t o s e v e r a l o f i t s a n a l y t i c a l procedures ( r e f s . 110-112). The technique o f s p a r g i n g a water sample o f
i t s v o l a t i l e s and c o l l e c t i n g them
i n a cooled t r a p i s c r e d i t e d t o Swinnerton and Linnenbom ( r e f s . Their
main work
in t h i s
hydrocarbons i n seawater.
area
was
the
identification
A sensitivity of
0.1
and
38,
4 2 and 113-115).
q u a n t i f i c a t i o n of
p p t was a c h i e v a b l e because o f
lower the
l a r g e sample volume and t h e c o n c e n t r a t i n g step i n t h e procedure. Vapor s t r i p p i n g t e c h n i q u e s p r e s e n t a p r o b l e m o f c a l i b r a t i o n b e c a u s e t h e e f f i c i e n c y i s a f u n c t i o n o f t h e s o l u t e and t h e i o n i c s t r e n g t h .
The use of an i n t e r n a l
111 standard o r an i n t e r n a l standard o f a labeled isotope o f t h e component o f (e.g.,
interest
deuterated benzene) w i l l e l i m i n a t e t h i s problem ( r e f . 116). T h i s sample treatment technique i s very s i m i l a r t o t h e sampling technique by
adsorption discussed
i n Chapter 3 ( S e c t i o n 3.4).
The reader
Is referred t o t h i s
chapter f o r more i n f o r m a t i o n . Several b o i l i n g p o i n t l i m i t s ( f o r purgeable compounds) have been s t a t e d i n t h e literature.
Grote and Westendorf ( r e f . 1 1 7 ) s e t t h e b o i l i n g p o i n t l i m i t a t 15OOC and
a water s o l u b i l i t y o f 3%. whereas H i t e s ( r e f . 118) has s t a t e d a l i m i t o f 100°C f o r t h e b o i l i n g point. Be1 i a r e t a l .
(ref.
applied t h e i r
119)
determination o f v i n y l c h l o r i d e ,
a t t h e vg/e
"purge
and t r a p "
l e v e l by gas chromatography.
was t h e purging gas and t h e adsorbent was e i t h e r s i l i c a gel
A halogen-specific
temperature.
technique t o t h e
d e t e c t o r was used.
Nitrogen
o r Carbosieve a t room
Some new columns were used f o r
t h e separation and determination of organic p o l l u t a n t s i n water by Mindrup ( r e f . 120). The v o l a t i l e s were removed by "purge and t r a p "
technique and determined on a 80-100
mesh Carbopack C/O.2%
Oowty
Carbowax
1500 column.
et
al.
(ref.
121)
determined
halogen and nonhalogen c o n t a i n i n g p r i o r i t y p o l l u t a n t s a t t h e < 1 vg/& ( 1 ppb) l e v e l . They increased t h e i r b y e (ref.
from t h e sample. ethers,
s e n s i t i v i t y by use o f "purge and t r a p "
and mass spectrometry.
122) trapped p o l a r water-soluble compounds on Tenax GC a f t e r g a s - s t r i p p i n g The types o f compounds t e s t e d were alcohols,
halogenated hydrocarbons and aromatic hydrocarbons.
methanol
and ethanol,
l e a s t 75% e f f i c i e n t . n i t r o g e n gas.
most o f
the strippings,
adsorptions
aldehydes,
ketones,
With t h e e x c e p t i o n o f and d e s o r p t i o n s were a t
Dissolved n i t r o u s oxide i n seawater was s t r i p p e d (purged) u s i n g
The gas was adsorbed on molecular s i e v e 13X a t 0°C.
Thermal d e s o r p t i o n
was done a t 250OC and t h e n i t r o u s o x i d e determined on a molecular s i e v e 5A column a t 25OOC u s i n g e l e c t r o n - c a p t u r e d e t e c t i o n ( r e f . 123).
4.3.2.3
Change i n i o n i c s t r e n g t h o f sample s o l u t i o n .
The removal of nonpolar
o r compounds o f low p o l a r i t y from t h e aqueous phase i n t o t h e gas phase may have t o be enhanced f o r several reasons. ( 1 ) The c o n c e n t r a t i o n level
equilibration,
a t which they are present
i s very low and vapor
p u r g i n g or sparging may not t r a n s f e r a s u f f i c i e n t a m u n t t o t h e gas
phase f o r accurate d e t e c t i o n .
( 2 ) One d e s i r e s t o approach q u a n t i t a t i v e t r a n s f e r
( a t l e a s t 95%) o f t h e
components from aqueous phase t o gas phase. The s i m p l i e s t technique t o increase t h e amount o f p o l l u t a n t i n t h e gas phase i s t o increase t h e i o n i c s t r e n g t h o f t h e sample. compounds w i l l
The r e s u l t i s t h a t t h e low p o l a r i t y
have more i n t e r a c t i o n among themselves which r e s u l t s
i n t h e i r p a r t i a l pressures. o f t h e aqueous phase ( i . e . ,
Thus, one has "squeezed" one has s a l t e d them o u t ) .
i n an
increase
these low p o l a r i t y molecules o u t T h i s i s accomplished by adding
enough o f a s o l u b l e e l e c t r o l y t e t o form a very concentrated s o l u t i o n o r i n some cases
112 Compounds such as NaCl, Na2S04 and (NH4)2S04 ( r e f . 8 7 )
t o s a t u r a t e t h e aqueous phase.
as we1 1 as CaCOj ( r e f . 8 8 ) have been used. The same e f f e c t i s seen I n performing a l i q u i d - l i q u i d e x t r a c t i o n w i t h water as The a d d i t i o n of a l a r g e s a l t c o n c e n t r a t i o n t o t h e water phase
one o f t h e phases.
It Is
would enhance t h e e x t r a c t i o n o f low p o l a r i t y compounds i n t o t h e o r g a n i c l a y e r . n o t w i t h i n t h e scope o f t h i s book t o discuss t h e t h e o r y o f
out, etc.
i o n i c strength,
salting
One may f i n d i n f o r m a t i o n r e g a r d i n g i t s b e n e f i t s by reading t h e a p p r o p r i a t e An e x c e l l e n t treatment o f t h i s t o p i c
s e c t i o n i n a p h y s i c a l chemistry textbook. given by Glasstone ( r e f . 1 2 4 ) .
i n c r e a s e d i o n i c s t r e n g t h f o r t h e headspace gas a n a l y s i s t e c h n i q u e , addltlon,
for hydrophilic
is
Drozd and Novbk ( r e f . 92) have s t u d i e d t h e e f f e c t o f
s o l u t e s (e.g.,
acetone,
methanol,
ethanol
by standard
and p r o p a n o l ) .
The increase i n i o n i c s t r e n g t h demonstrated an Increased s e n s i t i v i t y f o r acetone and propanol.
4 . 4 CLEAN-UP
Sample clean-up
i s used when an environmental sample c o n t a i n s o r
t o c o n t a i n a wide v a r i e t y o f components.
i s suspected
The goal o f t h i s procedure i s t o i s o l a t e
groups o f compounds so t h a t I n j e c t i o n o f an a l i q u o t o f t h e e x t r a c t i n g s o l v e n t does n o t r e s u l t i n a very complicated chromatogram ( l . e . , which
leave t h e data
t h e removal of unwanted components
i n doubt as t o r e l i a b i l i t y ) .
The s i m p l i e s t approach t o t h i s
problem i s t o pass t h e sample as r e c e i v e d ( o r an e x t r a c t o f t h e sample) through a clean-up column t o o b t a i n an i n l t i a l group separation. A c t i v a t e d charcoal
( r e f s . 125 and 126) and t h e v a r i o u s porous o r g a n i c polymers
a r e w i d e l y used t o ' c l e a n up and c o n c e n t r a t e p o l l u t a n t s f r o m w a t e r . techniques,
carbon-chloroform
illustrations
of
adsorption-extraction
Charcoal has advantages (e.g., and disadvantages (e.g., not
always
e x t r a c t (CCE) and carbon-alcohol
quantitative
systems
for
clean
The t w o
e x t r a c t (CAE) a r e two up
of
water
h i g h a d s o r p t i o n c a p a c i t y and h i g h thermal
samples. stability)
organic compounds a r e n o t adsorbed completely; d e s o r p t i o n I s and t h e
desorption
process
sometimes changes
the
sorbate
molecules) ( r e f . 1 2 7 ) . Porous polymers a r e good f o r
c l e a n i n g up water
samples
because t h e proper
sorbent causes a s h i f t i n e q u i l i b r i u m towards t h e sorbent more than toward t h e o r g a n l c phase i n a I l q u i d - l l q u i d e x t r a c t i o n .
The c o n c e n t r a t i o n f a c t o r
l i q u i d - s o l i d e x t r a c t i o n than f o r l i q u i d - l i q u i d e x t r a c t i o n .
will
be g r e a t e r
for
Porous polymers have some
unique p r o p e r t i e s which make them t h e choice f o r c l e a n i n g up and c o n c e n t r a t i n g water pollutants.
I f t h e proper porous polymer i s selected, t h e d i s t r i b u t i o n constants (KD)
tend toward i n f i n i t y . surface
i s inert;
Adsorption o f water
and t h e i r
"wetability"
organlc p o l l u t a n t s from t h e water.
is
i s minimal low which
a t best;
t h e porous polymer
increases t h e a d s o r p t i o n o f
The more hydrophobic i s t h e sorbent surface,
more adsorption c a p a c i t y i s a v a i l a b l e f o r non-polar
the
(or low p o l a r i t y ) molecules i n t h e
113 water phase ( a s molecule p o l a r i t y decreases, t h e water solubility decreases). Removal o f organic molecules from t h e surface o f t h e porous polymer may be accomplished
by
liquid-desorption
(see above,
Solvents o t h e r
than c h l o r o f o r m and alcohol
d i e t h y l ether,
n-hexane,
pyridine.
acetone,
Experience
with
e.g.,
which
isopropanol,
thin
layer
or
CCE and CAE) have been used
methanol,
methyl
liquid-solid
or
by
lsobutyl
are
ketone and
chromatography
advantageous i n t h e sample clean-up process and f a m i l i a r i t y w i t h Snyder's
will
(ref.
be 128)
A word o f c a u t i o n i n
e l u o t r o p i c solvent s e r i e s would be a g r e a t asset t o t h e novice. t h e use o f t h e e l u o t r o p i c s o l v e n t s e r i e s :
heating.
successfully
when using non-polar
porous polymers an
increase i n s o l v e n t s t r e n g t h wiI I g i v e t h e o p p o s i t e e f f e c t (more a d s o r p t i o n and less desorption). n-hexane
The best
solvents
benzene
>
> d i e t h y l e t h e r > propanol > acetone > ethanol
>
for
> e t h y l acetate > butanol
desorption
would
follow t h e order
methanol > water ( r e f . 1 0 ) . Desorption volume o f t h e e l u e n t
i s usually
i n t h e range o f
10-25
mi.
This
l i q u i d desorption step as w e l l as t h e c o n c e n t r a t i n g step ( e v a p o r a t i o n t o a smaller volume) which f o l l o w s ,
introduces e r r o r .
sample may a l s o cause an e r r o r I t may
solvent.
i n t e r f e r e or
s o l v e n t peak may be removed,
The
because o f
large amount o f e l u e n t
the
completely cover
e.g.,
if
l a r g e peak
i n the final
which r e s u l t s from t h e
a p o l l u t a n t peak.
p y r i d i n e were used f o r
Sometimes t h e
t h e desorption,
the
sample pulse could pass through a small precolumn c o n t a i n i n g CuCI2 and t h e p y r i d i n e s e l e c t i v e l y removed ( r e f . 129). of high p u r i t y measuring.
-
NOTE:
The s o l v e n t ( s ) used f o r t h e d e s o r p t i o n must be
they may c o n t a i n no more than a ppm o r ppb o f t h e component one i s
One
should
purify
all
solvents
chromatographed, a t a h i g h s e n s i t i v i t y s e t t i n g , Table 4 . 4
used,
unless,
when
they
i s a t a b u l a t i o n o f a number of comnonly used s o l i d s i n clean-up
c o n c e n t r a t i o n o f p o l l u t a n t s i n water.
are
no i n t e r f e r e n c e peaks a r e noted. and
We have given p r o p e r t i e s and s e l e c t i v i t i e s o f
these v a r i o u s s o l i d adsorbents so t h a t they may be used as a r e f e r e n c e p o i n t i n water p o l l u t i o n analysis.
A c i d i c compounds were found t o be e a s i l y desorbed w i t h aqueous
NaOH, whereas b a s i c components a r e e l u t e d w i t h d i l u t e HCI.
TABLE 4 . 4 S o l i d sorbents used f o r clean-up and c o n c e n t r a t i o n o f water p o l l u t a n t s Sorbent
AmberIite XAD-2
Chemical make-up
Styrene-divinyl-benzene copol ymer
Chemical and p h y s i c a l properties
Compounds sorbed*
Recovery
Ref.
Hydrophobic. Pore diameter, 85-90 A. S p e c i f i c surface2 area: 290-330 m /g. 20-50 mesh.
alcohol^ ( 1 0-1 00 PPb)
91-102
130
A I dehydes and ketones (10100 ppb)
92-1 02
130
(Z)
114 Sorbent
Chemical make-up
Chemical and p h y s i c a l properties
Compounds sorbed*
Recovery
Ref.
E s t e r s (10100 p p b )
91-103
130
PAHs (10100 p p b )
92-101
130
Alkylbenzenes (10-100 PPb)
ca. 93
130
(%)
Ha I ogen93-99 ated arom a t i c hydrocarbons (10-100 p p b )
130
Aromatic amines ( 1 0 100 p p b )
130
91-100
Nitro-cornpounds, a n i I ines, quinol i n e s , (10100 p p b )
AmberIite
Styrene-divinylbenzene copolymer
Hydrophobic. Specifi c s u r f a c e a r e a : 750 m2 /g.Av. p o r e diame t e r , 50 A .
Ethers 91-99 (aromatic) (10-100 p p b )
130
Pesticides herbicides (20 p p t )
93-96
130
Alcohols (2-10 p p b )
93-103
131
Esters (2-10 ppb)
91-99
131
Aldehydes and k e t o n e s (2-10 p p b )
92-105
131
(65-30) A l k y l benzenes ( 2 - 1 0 PPb)
131
PAHs (2-10 ?Pb)
(83-87)
131
93-105
131
Phenols (alkylated) (2-10 p p b )
115 Sorbent
Chemical make-up
Chemical and physical properties
Amber-
Styrene-divinyl-
Ilte XAD-1
benzene copolymer
Specific surface 2 area: lOOm /g. Mean,, pore diameter: 200 A.
Compounds sorbed*
Recovery
Aromat ic ch Io r 0 compounds (2-10 ppb)
91 -93
131
Ac I ds (2-10 ppb)
90-1 07
131
Pheno I s (ha I ogenated) (210 ppb)
91 -99
131
Deter-
100
132
Insect i cides, pH = 2.0
100
132
Methy I ene blue, rhodamine blue, pH = 7.6
100
132
Hum ic acids. pH = 2.0
100
132
Vitamins B2 and B,2
100
132
100
132
93
133
Benzene
100
133
Methy I i sobuty I ketone
100
133
o-Ethy I p heno I
97
133
90
135
Ref.
(P)
gents, pH = 2.0
-
DH = 2.0 and 7.6 respectively. Cholesterol pH = 2.0 Chromosorb S t y r e n e - d i v i n y l 102 benzene copolymer
Tenax-GC
Hydrophobic. Chloroform S p e c i f i c surface area 2 300-400 m /g. Meano pore diameter: 95 A.
Poly
S p e c i f i c surface
Pest i c I des
(2,6-d ipheny l -
area: 19-30 m'/g. Pore volume: 0.667
( f r e e C12 i n water
116 Sorbent
Chemical make-up
Chemical and physical properties ml/g ( r e f . 134). Av pore r a d l u s : 720 A. Good sorbent up t o 320°C. Reaction w i t h n l t r o g e n oxide o r n l t r l c a c i d does not a f f e c t i t s e f ficiency or capacity.
p-pheny Iene oxide)
Polyurethane, open pore
Urethane PO I ymer
1-10 um agglomerated s p h e r l c a l p a r t i c l e s bonded together. Bases break up openpore s t r u c t u r e . S t a b i l i t y increased as pH o f water sample decreased.
Po l yurethane porous foam
U r ethane polymer.
pH 6-9. Increased water f I ow r a t e causes decreased ads o r p t ion.
Compounds sorbed"
Recovery
Ref.
(I)
causes oxidation of pesticides)
-
PAHs (0.1 ppb l e v e l )
85-90
135
Benzene, aniline, p-creso I
89-99
136
92-108
137
.
PAHs
Ch l o r i nated insect 1 c i d e s and poly-chlor1 nated b 1 pheny I s.
97-114
138
-
-
PAHs Amberl y s t A-26 i o n ex-
MacroretlcuI ar
change resin.
porous po I ymer
*By
.
Anion-exchange r e s i n with trimethylamine group. S p e c i f i c sur2 face area: 25-30111 / g. 27% p o r o s i t y .
Pheno I s (pH 1212.5)
pH 3.0,62 pH 10.0,76
139
95-102
127
group or i n d i v i d u a l compound l i s t i n g .
**Individual
compounds l i s t e d had t o have a minimum o f 90% recovery.
Recovery ( $ ) =
((Amount remaining a f t e r c o n c e n t r a t i o n s t e p ) / ( A m u n t o r i g i n a l l y present I n s o l u t i o n ) ) x 100.
Once t h e components o f
t h e water
sample have been removed ( d e s o r b e d ) a g r o u p
s e p a r a t i o n may be used t o s e l e c t i v e l y remove g r o u p s o f compounds. separation i s dependent on pH ( r e f . compounds are not sorbed.
T h i s group
140) because s t r o n g l y i o n i c organic o r i n o r g a n i c
117 WATER SAMPLE clean-up by a d s o r p t i o n
Wash w i t h
REMOVAL OF
I
I M HCi*
I
AC iD I C SORBATE:
REMOVAL OF
Wash w i t h __j
BAS I C SORBATES
*
COMPONENTS CONCENTRATED ON SOLID SORBENT
0.05 M NaOH
REMOVAL OF
A
d i e t h y l ether
Recoveries 7-75 $ w i t h o n l y d i s t i l l e d water; 40-108
Use o f a f i n e r p a r t l c l e s l z e (ca. ppm range,
Wash w l t h
NEUTRAL SORBATES
%
w i t h HCI.
150 mesh), v a r y i n g s o l u t e c o n c e n t r a t i o n from ppb t o
changing t h e f l o w r a t e o f t h e moblle phase, and t h e a d d i t i o n o f up t o 50 g
NaCl per l i t e r produced l i t t l e or no change I n t h e r e c o v e r i e s . The Amberlite XAD-7 sorbent i s a h y d r o p h l l l c m e t h a c r y l a t e polymer having a 0 T h i s i s a good s p e c i f i c surface area o f 450 m2/g and a mean pore diameter o f 80 A . clean-up sorbent f o r f a t t y acids, phenol,
and m-chlorophenol.
Adsorption increases as
t h e f a t t y a c i d chain length Increases ( s o l u b i l i t y decreases).
The polymer i s u n s t a b l e
i n a l c o h o l i c sodium hydroxide s o l u t i o n (causes h y d r o l y s i s o f t h e e s t e r group). A m b e r l i t e XAD-8 r e s i n i s a methyl m e t h a c r y l a t e r e s i n w i t h average p o r e diameter
2
o f 250 A and s p e c i f i c surface area o f 140 m /g.
The r e s i n adsorbs a l i p h a t i c systems
i n p r e f e r e n c e t o a l i c y c l i c a n d / o r a r o m a t i c c a r b o n systems.
> -NH2. f u n c t i o n a l groups i s -CH3 > -COOH > -CHO > -OH an inverse of s o l u b i l i t y trends.
One o f
The p r e f e r e n c e f o r
Both o f these preferences a r e
i t s main uses i s t h e c o n c e n t r a t i o n o f
molecular weight organic s o l u t e s and n a t u r a l o r g a n i c p o l y e l o c t r o l y t e s (e.g.,
low
fulvic
and humic a c i d s ) . A n o t h e r g r o u p o f s o r b e n t s w h i c h may be used f o r c l e a n - u p Polymers (manufactured by Waters Associates,
Framingham, MA,
USA).
i s t h e Porapak Porapak Q I s an 0
ethylvinylbenzene-divinylbenzene copolymer having a mean micropore diameter o f 74.8 A 0
a v a i l a b l e up t o 500 A )
142).
and a s p e c i f i c s u r f a c e area o f
2 630-840 m /g
(refs.
The polymer has i t s b e s t a p p l i c a t i o n f o r t h e c o n c e n t r a t i o n o f
hydrocarbons (e.g.,
benzene, toluene, o-xylene,
naphthalene).
Adsorbed o r g a n o s i l i c o n
compounds can be removed by e l u t i o n w i t h methyl i s o b u t y l ketone ( r e f . 143). (manufactured by Lachema, s i m i l a r t o Porapak Q.
Brno,
Czechoslovakia)
141 and aromatic
Synachrom
i s a copolymer w i t h p r o p e r t i e s very
The s o r p t i o n process i s physical
sorption;
thus,
s o r p t i o n on
t h i s copolymer i s i n v e r s e l y p r o p o r t i o n a l t o s o l u b i l i t y o f sorbates i n water. Porapak N i s n o t a very good copolymer f o r clean-up purposes. Porapak Q i t i s found t h a t 143).
Comparing i t t o
i t possesses no abi I i t y t o t r a p s i I icon compounds ( r e f .
118 TABLE 4.5 Comparison o f various types o f a m b e r l l t e ( r e f . 144)
Compound
Concentratlon (ppb) 50
Acenaohthene 2-benzothiazole Bis(2-chloroisopropyl)Bther p-Cresol D i benzof uran n-Hexadecane I-Methylnaphthalene 2-Methylnaphthalene o-Nitrotoluene Naphthalene Pheno I -Ter p i neo I sym-Tetrachloroethane Dehydroabietic a c i d 100 Di-2-ethylhexyl phthal a t e 2-Ethyl hexanol lsophorone Palmitic acid Pentachlorophenol 1 -BHC L i ndane -B Hc Aldrin Die I d r i n Cumene 10,000 Ethylbenzene Naphthalene n-Hexane Pheno I Octanolc a c i d o-Creso I Chiorophenol
Recovery(%) f o r XAD r e s i n t y p e 1 2/4 8 217 2 2/8 2/4/1/8 50 40
84 82
81
81
81 14
76 50 83 8 15 72 79 77 32 71
16 44 93 3 76 15 82 79 14 81
80 69 82
64 63 53 64 19 36
11 47 95 80 11 11 78 29 62
71 83 80 38 80
82 68 84 11 19 77 83 80 46 80
35 31
59 85
66
61 94
12 86
-12
22 74 46 12 83 -
13 79 41 16 11 28 11
---
33
11 91 86 79 84 90 107 81 50 107
13
3
-
61 59 93 83 45 81 67 a5 ..
-
63 82
-
85
12
20 75
33
99
4/8
68 53
-
72
4
-
77
85 16 61 84 53 45 71 51 61 61 60 90 82 27 58 59 70
Ref. >
145
145
9
146
10 32 25 25
-
-
-
141
(by permission o f p u b l i s h e r . )
Another group o f polymers which may be used i s t h e Chromosorb Century Series. Chromosorb 105 I s a p o l y a r m a t l c t y p e polymer having an average p o l a r i t y , and average 2 T h i s polymer pore diameter of 0.04-0.06 p m and s p e c i f i c surface area of 600-700 m /g. i s not recommended f o r clean-up
properties.
Chromosorb 106 i s very s i m i l a r t o t h e
Chromosorb 105. Table 4.5
i l l u s t r a t e s a comparison o f t h e various types and/or m i x t u r e s o f t h e
Amberlite XAD r e s i n s . the
most
efficient
The data show t h a t a 1 : l m i x t u r e o f XAD-4 and
that
resin
XAD-4
is
very
and XAO-8 r e s i n s i s
efficient
for
chlorinated
119 insecticides.
XAD-7
i s a b e t t e r sorbent than XAD-2 for p o l a r compounds,
has a h i g h e r p o l a r i t y . water
studies
XAD-8
because
it
i s most s u i t a b l e ( a s compared t o XAD-2) has
less
tendency
to
become
because XAD-7
f o r natural
clogged
by
natural
p o l y e l e c t r o l y t e s ( r e f . 144). A comparison o f t h e r e c o v e r i e s w i t h XAD-2
300) was made by C h r i s w e l l e t a l . ( r e f . 148). d a t a show t h a t t h e p o r o u s p o l y m e r ,
XAD-2,
and a c t i v a t e d charcoal
(Filtrasorb
These data a r e shown i n Table 4.6. i s more s u i t a b l e t h a n c h a r c o a l
The for
r e c o v e r i e s o f t h e v a r i o u s sorbates except f o r a c i d i c t y p e compounds ( n e i t h e r sorbent i s acceptable) o r alkanes.
A s i m i l a r study between A m b e r l i t e XAD-4
and Spherocarb
(carbon molecular s i e v e ) f u r n i s h e d e s s e n t i a l l y t h e same i n f o r m a t i o n ( r e f . adsorption
capacity of
carbon
is
lower
than Amberlite
XAD r e s i n s ,
131).
The
Synachrom and
open-pore polyurethanes ( r e f . 10).
TABLE 4 . 6
Comparison o f r e c o v e r i e s w i t h A m b e r l i t e XAD-2 and a c t i v a t e d carbon ( r e f . 148) (by permission o f p u b l i s h e r ) Compound
Number o f i n v e s t i g a t e d compounds
Recovery ( % 1 Resin Carbon
A I kanes Esters A l coho I s Phthalate esters Pheno I s C h l o r i n a t e d alkanes and alkenes C h l o r i n a t e d aromatic compounds Aromatic compounds Aldehydes and ketones Amines C a r b o x y l i c acids Pesticides M i sce I I aneous
5 4
5 61 73 82 45 43 70 68 74 54 1 34 33
a
3 10 5
13 7 3
13 11 4 14
15 49 47 24
7 55 11 6 4 54 2 16 11
M a r c e l i n ( r e f . 149) used Tenax-GC as a clean-up packing when a n a i y z l n g m i x t u r e s of
permanent gases
and heavy organic
compounds.
A
short
pre-column
of
Tenax-GC
adsorbed t h e organic m a t e r i a l and passed t h e permanent gases and water i n t o a column o f Chromosorb 101 f o l l e d by a column o f Porapak QS f o r separation.
Thermal d e s o r p t i o n
o f t h e organic m a t e r i a l and separation on a 10% XE-60/Chromosorb WHP column followed. A clean-up
and c o n c e n t r a t i o n system f o r
described by Solomon ( r e f .
150).
chlorinated
i n s e c t i c i d e r e s i d u e s has been
Hexane s o l u t i o n s o f t h e c h l o r i n a t e d p e s t i c i d e s were
chromatographed on a F l o r i s i l column and e l u t e d w i t h hexane-dlethyl Recoveries o f 87-100% were reported.
Baird e t a l .
t h e e f f l u e n t s from four p i l o t t e r t i a r y waste-water compounds.
ether
solvent.
( r e f . 1 5 1 ) c a r r i e d o u t a study on treatment systems f o r t r a c e o r g a n i c
The e f f e c t s of ozone and f r e e and combined c h l o r i n e were a l s o studied.
They used various combinations o f alum f l o c c u l a t i o n , for
removal
of
volatile
chlorinated pesticides,
filtration,
polynuclear
and p o l y c h l o r i n a t e d biphenyls.
and carbon a d s o r p t i o n aromatic
hydrocarbons,
Gas chromatography was t h e
Carbon adsorption reduced t h e t r i h a l o m e t h a n e l e v e l s almost 90%.
method o f analysis. Chang and F r i t z
halogenated organics,
152) used macroporous
(ref.
XAD-2
r e s i n t o c o n c e n t r a t e and then
determine various p o l l u t a n t s i n water. Average recovery was 83% a t t h e 3-200 9 ( 1 0 ) l e v e l , w i t h an o v e r a l l r e p r o d u c i b i l i t y o f 5-8$.
ppb
4 . 5 DERlVATlZATlON D e r i v a t i z a t i o n i s t h e process o f c h e m i c a l l y m o d i f y i n g a molecule i n order t o make I t more ccmpatible w i t h an a n a l y t i c a l procedure.
T h i s i s n o t a process unique t o
D e r i v a t i z a t i o n s are performed f o r a v a r i e t y o f reasons:
chromatographic separation.
( 1 ) To increase v o l a t i l i t y o f a component or t o increase I t s thermal s t a b i l i t y
i .e.,
f o r gas chromatography,
improve t h e chromatographic behavior o f t h e component.
An example would be t h e s l l y l a t i o n o r a c e t y l a t i o n r e a c t i o n s o f hydroxyl o r c a r b o x y l i c a c i d groups.
In l i q u i d chromatography t h i s may be used t o change t h e p o l a r i t y o f t h e
parent molecule, The
sensitivity
e.g.,
conversion o f a l c o h o l s t o e t h e r s o r c a r b o x y l i c a c i d s t o e s t e r s .
in
liquid
chromatography
may
nitro-substituted ester of the carboxylic acid. nitro-substituted
ester
is
greater
than
the
be
increased
simple
ester.
The
f l u o r m e t r i c d e r i v a t i v e p r i o r t o t h e Separation a l l o w s t h e use o f d e t e c t o r and increases t h e s e n s i t i v i t y a hundred-fold
(21 To f a c i l i t a t e t h e s e p a r a t i o n o f
by
forming
a
The m o l a r a d s o r p t i v i t y o f t h e making
of
a
a fluorometric
( r e f . 153).
components
i n a mixture:
The p a r e n t
molecule may be changed t o another chemical form which has a r e t e n t i o n t i m e d i f f e r e n t
from t h e parent molecule.
This technique may be used i n gas chromatography as w e l l as
i n l i q u i d chromatography; however,
i t s use i n l i q u i d chromatography i s l i m i t e d because
o f t h e v a r i e t y o f s o l v e n t systems a v a i l a b l e . n o t g i v e a more s e n s i t i v e s i g n a l e.g.,
f r e e acids o r amines,
In t h i s a p p l i c a t i o n t h e d e r i v a t i v e need
than t h e parent molecule.
Very p o l a r compounds,
are d i f f i c u l t t o separate b y gas chromatography as are
some t h e r m a l l y l a b i l e compounds.
The chemical m o d i f i c a t i o n o f t h e f u n c t i o n a l
group
improves t h e chromatographic behavior of t h e molecules ( i t s abi I i t y t o be determined b y gas chromatography).
( 3 ) To increase t h e d e t e c t a b i l i t y by imparting a measurable c h a r a c t e r i s t i c t o t h e parent molecule:
P o l l u t a n t s are u s u a l l y present i n t h e ppm o r ppb range and one
may increase t h e s e n s i t i v i t y o f t h e method by forming a halogen or acyl ( t a g g i n g w i t h a p e r f l u o r o a l k y l o r acyl group).
c a r r i e d o u t by use of an e l e c t r o n - c a p t u r e d e t e c t o r .
A minimal r e s u l t a n t Increase i n
s e n s i t i v i t y by a f a c t o r o f a thousand i s o f t e n obtained. or s o i l s may e a s i l y be detected i n t h i s manner.
derivative
In t h i s manner t h e d e t e c t i o n can be
P e s t i c i d e r e s i d u e s i n food
One may extend t h e u t i l i t y o f
iiquid
chromatography d e t e c t o r s by t a g g i n g molecules o f i n t e r e s t w i t h s t r o n g UV chromophores
121 o r w i t h a flUorophore ( f o r f l u o r e s c e n t d e t e c t o r s ) .
There a r e a number of reagents
a v a i l a b l e f o r making d e r i v a t i v e s o f molecules t o enhance t h e i r d e t e c t a b l l i t y .
These
reagents may be grouped according t o t h e type o f parent molecule and reagent type. Parent molecules having a r e p l a c e a b l e hydrogen e a s i l y react, and phenols.
Halogenated t r i m e t h y l s i l y l
trifluoroacetic
anhydride
(TFAA),
h e p t a f l u o r o b u t y r i c anhydride
(TMS)
e.g.,
derivatives
pentafluoropropionic
(HFBA) are commonly used.
amines,
are
very
anhydride
form d e r i v a t l v e s w i t h
Also
(PFPA),
and
These d e r i v a t i v e s n o t o n l y
increase t h e d e t e c t a b l l l t y b u t a l s o a i d i n v o l a t i l i t y and s t a b i l i t y . amines
alcohols
good.
A l c o h o l s and
N-trifluoroacetylimidazole and N - h e p t a f i u o r o b u t y r i m i -
A very good reagent f o r primary and secondary amines i s p e n t a f l u o r o b e n z o y l -
dazole. ch Io r i de.
I f d e r i v a t i z a t i o n i s t o be used, one must decide I f t h e chemical t r a n s f o r m a t i o n
w i l l t a k e place b e f o r e i n j e c t i o n o n t o t h e column (pre-column d e r i v a t l z a t l o n ) ,
during
t h e separation process i n t h e column (on-column d e r i v a t i z a t i o n ) o r a t t h e completion o f t h e separation (post-column d e r i v a t i z a t i o n ) . ( a ) Pre-column d e r i v a t i z a t i o n
i s used when t h e d e r i v a t i v e f o r m a t i o n r e a c t i o n
t i m e I s long o r may r e q u i r e d r a s t i c c o n d i t i o n s .
The chemical r e a c t i o n may t a k e p l a c e
o v e r n i g h t followed by gas o r l i q u i d chromatographic s e p a r a t i o n o f t h e product. ( b ) On-column d e r i v a t i z a t i o n may make use o f t h e heated i n J e c t i o n p o r t and/or column ( i n gas chromatography) t o e f f e c t t h e chemical r e a c t i o n .
D e c i s l o n making on
t h e system can n o t w a i t u n t i l t h e n e x t day because d e r i v a t i v e s made t h i s way must have f a s t r e a c t i o n t i m e and be a c l e a n r e a c t i o n .
This technique i s p r e f e r r e d over
p r e - c o l u m n d e r i v a t i z a t l o n because of t h e speed and s i m p l i c i t y .
These t y p e s o f
d e r l v a t i v e s (gas chromatography) mean m o d i f i c a t i o n t o system equipment. procedures are t o be used on a r o u t i n e basis,
Unless these
one should consider doing pre-column
derivatization. ( c ) Post-column rather
than
enhanced. derivative; derivative.
derivatization
i n gas chromatography
is
primarily
used
in
liquid
chromatography
so t h a t t h e d e t e c t a b i l i t y o f t h e components
is
This i n v o l v e s t h e separation o f p a r e n t compounds and t h e d e t e c t i o n of t h e whereas,
w i t h a and b.
t h e Separation and d e t e c t i o n a r e based upon t h e
T h i s mode o f d e r i v a t l z a t l o n introduces t h e p o s s i b i l i t y o f m i x i n g o f t h e
separated components of t h e sample a f t e r they e x i t from t h e column and b e f o r e t h e y enter t h e detector. I n a l l t h r e e techniques, m a t r i x e f f e c t s can I n t e r f e r e . be c e r t a i n o f t h e q u a l i t a t i v e make-up o f t h e sample. i n t e r f e r e n c e i s pH,
Thus It i s e s s e n t i a l t o
One parameter which can cause an
because t h e change i n hydrogen i o n c o n c e n t r a t i o n may i n h i b i t t h e
r e a c t i o n o f I n t e r e s t o r a c c e l e r a t e an unwanted r e a c t i o n .
A reagent t o be useful f o r d e r i v a t i z a t l o n should meet c e r t a l n c r i t e r i a : ( 1 ) it should form no more than one d e r i v a t i v e w l t h each p a r e n t compound.
( 2 ) Reaction completion should r e q u i r e minimum t i m e under m l l d c o n d i t i o n s .
122 ( 3 ) Any by-products or excess reagent should not I n t e r f e r e w i t h t h e s e p a r a t i o n o f t h e compounds o f i n t e r e s t .
I n o t h e r words,
non-UV a d s o r b l n g o r s u f f i c i e n t l y d l f f e r e n t
r e a c t i o n by-producfs
should be e l t h e r
i n s t r u c t u r e from t h e d e r l v a t l v e o f
i n t e r e s t t h a t separatlon i s no problem.
( 4 ) D i f f s r e n c e s among t h e p a r e n t compounds should be preserved t o a l l o w t h e i r separation. S u b s t i t u t e d aromatic compounds are t h e most commonly used UV chromophores f o r l i q u i d chrunatography d e r i v a t i v e s .
They r e p r e s e n t t h e b e s t general compromise among
s i z e , p o l a r i t y , and molar a d s o r p t i v i t y . The most commonly used d e r i v a t i v e reagent f o r gas chromatography has been t h e s i l y l ether.
The r e a c t i o n between sample component and s i l y l a t l o n reagent i s f a s t and
A s i l y l d e r i v a t i v e may be made I f t h e
leaves a pure d e r l v a t l v e I n f a i r l y h i g h y i e l d .
sample component has a f u n c t i o n a l group w i t h sllyl acceptor a b i l i t y . with
oxygenated
derivatlve.
or
nitrogen-containing
functlonal
groups
Most compounds
w!lI
form
this
type
One can rank these f u n c t i o n a l groups I n o r d e r o f t h e i r a b i l i t y t o r e a c t
w i t h a s l l y l reagent.
Alcohols a r e more r e a c t i v e than phenols which are more r e a c t i v e
than c a r b o x y l i c acids,
which are b e t t e r t h a n amines and amides.
grouping t h e order o f
reactivity
Within a functional
I s primary > secondary > t e r t i a r y because s t e r i c
f a c t o r s p l a y an Important r o l e i n t h e formation o f d e r i v a t i v e s . There I s a wide v a r i e t y o f l i q u i d Chromatography.
derivatives
discussed here.
and
I l t t l e interest
carbohydrates and amlno a c i d s ) and so w i l l n o t be
t o t h e environmental chemlst (e.g.,
King ( r e f .
a v a i l a b l e f o r gas chromatography
Many o f these a r e f o r compounds which a r e o f
For a general d i s c u s s i o n o f d e r i v a t l z a t i o n see t h e book by B l a u and
1 5 4 ) , t h e book by Lawrence and F r e i ( r e f .
1 5 5 ) , and t h e s p e c i a l
issue o f
t h e Journal o f Chromatographic Science e d i t e d by Lawrence ( r e f . 1 5 6 ) .
A t t h e present tlme, pollutants.
gas chromotography, However,
t h e making o f
derivatives
i s not o f t e n performed f o r
The p o l l u t a n t s which a r e o f t h e most concern can e a s i l y be determined by gas chromotographyhass
spectrometry,
t h i s does not r u l e o u t t h e p o s s i b i l i t y
of
or
l i q u i d chromotography.
d e t e r m i n i n g by d e r i v l t l z a t l o n
p o l l u t a n t s which may be added t o t h e various p r i o r i t y p o l l u t a n t l i s t s throughout t h e w o r l d or t h e d e r i v a t i z a t i o n o f p o l l u t a n t s t o i n c r e a s e d e t e c t a b i l i t y .
We have
t a b u l a t e d d e r i v a t i v e s w h i c h may be used a t t h i s t i m e ( s e e T a b l e 4 - 7 1 , w i t h t h e p r o j e c t i o n t h a t higher molecular weight or interest.
I f t h i s comes t o pass,
compound w i l l
be needed.
less v o l a t i l e p o l l u t a n t s w i l l
become of
d e r i v a t i v e s which are more v o l a t i l e than t h e parent
Another
justification
for
derivatives
will
d e t e c t i o n o f p o l l u t a n t s i f t h e maximum a l l o w a b l e l i m i t s a r e lowered. t h e a n a l y t i c a l chemist w i l l need more s e n s i t i v e means of
detection.
be
for
the
I f t h i s occurs, lncorporatlng
f u n c t i o n a l groups i n t o a parent p o l l u t a n t molecule may make i t more e a s i l y detected (e.g.,
halogenated d e r i v a t i v e s so t h a t smaller amounts may be detected by e l e c t r o n -
capture d e t e c t o r s i n l i e u c f flame I o n i z a t i o n d e t e c t o r s ) .
123 The f o r m a t i o n o f d e r i v a t i v e s can impose some p e n a l t i e s w h i c h s h o u l d b e F i r s t o f a l I t h e t i m e f o r an a n a l y s i s w i l l
considered.
cost per sample analyzed.
-
derivatives
again
increase t h u s l n c r e a s l n g t h e
a d d i t i o n a l reagents w i l l be necessary t o form t h e
Secondly,
increasing t h e c o s t per sample analyzed.
Thirdly,
additional
Although most pol l u t a n t s a r e easi l y determined a t t h e present time,
t h e use o f
equipment w i l l become necessary w l t h i t s a d d i t i o n a l costs.
a derivative
and
i t s subsequent
determination
i s a straightforward
c o n f i r m i n g - t h e presence o f a p a r t i c u l a r p o l l u t a n t .
technique
for
T h i s i s e s p e c i a l l y t r u e f o r those
l a b o r a t o r i e s which do not have mass spectrometry c a p a b l l i t l e s . Sulfur-containing
acids,
I n atmospheric
diazomethane and t h e r e s u l t i n g e s t e r s
aerosols,
have been methylated w l t h
separated on a d i e t h y l e n e g l y c o l
column and d e t e r m i n e d w i t h a s u l f u r - s e n s i t i v e
detector ( r e f .
succinate
A similar
214).
technique converted carbamate p e s t i c i d e s t o s u l f o n i c e s t e r s and separated them on a LSX-3-1295
o r W-98 on CHromosorb W column 2 2 0 T ( r e f .
122).
N i t r o g e n was t h e c a r r i e r
gas and d e t e c t i o n was w i t h e i t h e r e l e c t r o n - c a p t u r e o r sulfur-mode detectors.
123) separated and q u a n t i f i e d 2,4,6-trichloro-
Solomon and K a l l a s ( r e f .
l e v e l s u s i n g a 0.1% QF-1
phenyl e t h e r d e r i v a t i v e s a t sub-ppb
flame photometric
chromotographic column and electron-capture
detection.
+ 0.1% OV-17 g a s - l i q u i d
C h l o r i n a t e d phenols may be
d e r i v a t i z e d w i t h diazomethane o r diazoethane o r a s i l a n l z i n g agent and then determined a t ng/ml
(ppb) l e v e l s using e l e c t r o n - c a p t u r e d e t e c t i o n ( r e f . 2 1 5 ) .
i f t h e phenol does
not c o n t a i n a group w i t h e l e c t r o n capture response, h e p t a f i u o r o b u t y r a t e may be used as the derivatizing
agent.
Recoveries o f
20-200 ppb level were g r e a t e r than 75%. of
phthalate esters
by
formatlon
of
the
f l u o r i n a t e d phenol
derivatives
at
the
Giam e t a l . ( r e f . 216) confirmed t h e i d e n t i t y the
N-(2-chloroethyl)phthalimlde
derivatives
f o l l o w e d by separation on a 3% SE-30 column and d e t e c t i o n w i t h a 63NI e l e c t r o n - c a p t u r e detector.
Cochrane
217)
(ref.
has reviewed t h e use o f chemical
p e s t i c i d e s p r i o r t o gas chromatographic o r analysis.
high-performance
derivatization of
l i q u i d chromatographic
I n gas chromatography t h e p e s t i c i d e s are d e r i v a t i z e d t o more s t a b l e and
v o l a t i l e products;
while
made t o
detectability.
increase
introduces e i t h e r
i n high-performance In
a chromophoric o r
I l q u i d chromatography,
high-performance
fluorophoric
group
liquid
derivatives are
chromatography,
i n t o t h e molecules.
one This
lowers t h e d e t e c t i o n l i m i t s below t h e ppm l e v e l . Cyanide ion may be detected by gas I i q u i d chromatography by c o n v e r t i n g I t t o cyanogen c h l o r i d e u s i n g c h l o r a m i n e T ( r e f . 218). H a l l c a n i d M-18
on Anakrom ABS
d e t e c t o r used f o r q u a n t i t a t i o n . environmental converted
to
--diketones chelating
i s used f o r
t h e separation
chelate
and an e l e c t r o n - c a p t u r e
D e t e c t i o n l i m i t s are 25 ng/ml
samples may be d e t e r m i n e d by gas metal
A p a c k e d column made f r o m 7 %
complexes
which
are
(25 ppb).
Metals i n
l i q u i d chromatography stable.
Fluorine
if first
substituted
a r e e x t r e m e l y s e n s i t i v e t o e l e c t r o n - c a p t u r e d e t e c t i o n and t h u s t h e
agent
of
choice.
The
hexafluormonothioacetyl
C u ( I I ) , Z n ( I i ) , N i ( l I ) , C d ( I I ) . and P b ( i i ) have been prepared.
acetonate
cmpiexes
of
D e t e c t i o n I i m i t s range
124 from t h e nanogram.to t h e picogram l e v e l s ( r e f . 219).
TABLE 4.7 D e r i v a t i z a t l o n used i n gas and l i q u i d chromatography P o l l u t a n t type
D e r l v a t l v e and/or
Comnents
Ref.
179
d e r i v a t i v e reagent Acidsccar-
o-p-Nitrobenzyl-N,N'-
L i q u i d chromatography
boxyl i c )
dllsopropyllsourea
pre-column d e r i v a t i v e . Long-
(PNBDI)
chain a c i d s separated from s h o r t - c h a i n a c i d s by adsorption.
p-Bromophenacyl
L i q u i d chromatography pre-
bromide (PBFB) w i t h
column d e r i v a t i v e .
18-Crown-6( 1,4,7,10,
s o l u t i o n may be chromotographed
13,16-hexaocxcyclo-
d ir e c t I y
180
Resulting
.
octadecane). Ac I ds
bis-Trimethyl-
Gas chromatography
(Fatty)
silyltrifiuoroace-
derlvative-pre-column.
157
tamide(BSTFA) + t r i methylchlorosilane (TMCS). 4-Bromomethyl-7-
L i q u i d chromatography pre-
methoxy coumarin
column d e r i v a t i v e .
181
( BMC )
Acids
BSTFA
+ TMCS
(phenolic)
A I coho I s
Gas chromatography d e r i v a t i v e
157
pre-column. Trimethyl-silyl
Gas chromatography d e r l v a -
(TMSIether
tive-pre-column.
158-1 62
3,5-Dinltrobenzoyl
L i q u i d chromatography,
155, I56
chloride(DNBC)
no f u r t h e r workup needed,
163,164
125 Pol I u t a n t t y p e
Der i v a t i ve and/or
Cmmen t s
Ref.
d e r i v a t i v e reagent
pre-column d e r i v a t i v e .
Pyruvoyl c h l o r i d e
L i q u i d chromatography,
(2.6-dini tropheny I )
f u r t h e r workup needed,
hydrazone
column d e r i v a t i v e .
p-lodobenzenesul-
L i q u i d chromatography,
fonylchloride
f u r t h e r clean-up,
no
165
requires
165
pre-column
derivative.
Benzoyl c h l o r i d e
L i q u i d chromatography,
166
pre-column d e r i v a t i v e , r e q u i r e s f u r t h e r clean-up.
p-N i trobenzoy I
L i q u i d chromstography, pre-
chloride
column d e r i v a t i v e ,
167
requires
f u r t h e r clean-up.
Aldehydes
Ox ime
Gas chromatography pre-
168
column d e r i v a t i v e .
and ketones
Methoxime
Gas chromatography pre-
169
column d e r i v a t i v e .
Phenylhydrazone
Gas chromatography p r e -
170
c o l umn d e r i v a t i v e .
Dinitrophenyl-
Gas chromatography p r e -
hydraz i ne
c o l umn der i v a t i ve.
p-Nitrobenzyl-
L i q u i d chromatography p r e -
oxyamine HCL(PNBA)
column d e r i v a t i v e .
Dansyl hydrazine
L i q u i d chromatography pre-
( 1 -dimethy I amino
c o l umn der i v a t i ve.
naphthalene-5s y l f o n y l hydrazine)
171-173
163,174
181
126
Pollutant type
D e r i v a t i v e and/or
Ref.
Comments
d e r i v a t i v e reagent
Am Ines
BSTFA
Gas chromatography precolumn d e r i v a t i v e ,
175
90°C
f o r 15 min, e t h y l a c e t a t e so Ivent.
N-DNP
Gas chromatography pre-
176-1 78
column d e r i v a t i v e .
N-Dimethylamino-
Gas chromatography pre-
methylene(DMAM1
column d e r i v a t i v e .
N-TMS
Gas chromatography pre-
182
183
column d e r i v a t i v e .
N-Trifluoro-
Gas chromatography pre-
acetamide(TFA)
column d e r i v a t i v e
N-Heptafluoro-
Gas chromatography pre-
160,189-
b u t y r i c acid(HFB)
column d e r i v a t i v e .
191
N-Pentafluorophenyl-
Gas chromatography pre-
1 89,192-
e s t e r (N-PF Pheny I 1
column d e r i v a t i v e
194
N-Pentafluoro-
Gas chromatography pre-
1 89,192-
benzylidine(N-PF)
column d e r i v a t i v e
194
184-1 88
Benzylidine).
N-Pentafluoro-
Gas chromatography pre-
189,192-
benzamlde(N-PF
column d e r i v a t i v e .
194
N-Pentafluoropro-
Gas chromatography pre-
195-1 98
p i o n y l (FFP)
column d e r i v a t i v e .
Benzamide)
PFB-car barnate
Gas chromatography pre-
1 99-20 1
column d e r i v a t i v e . Hoffman degradation
Gas chromatography pre-
202
127 Pollutant type
D e r i v a t i v e and/or
Ref.
Comnents
d e r i v a t i v e reagent
column d e r i v a t i v e .
Amines
CS2 w i t h -NH
(phenolic)
group. BSTFA w i t h
2
Gas chromatography pre-
175
column d e r i v a t i v e .
-OH group.
DNBC
L I qu i d chromatography derivative,
155,163
clean-up n o t
necessary, pre-column derivative.
2,6-(Nitrophenyl)
L i q u i d chromatography pre-
hydrazone
column d e r i v a t i v e ,
165
no clean-
up necessary.
p-Methoxybenzoyl
L i q u i d Chromatography pre-
ch l o r i de
column d e r i v a t i v e ,
203
clean-up
necessary b e f o r e sample i n jection.
Am i nes
N-Succinimidyl-p-
L i q u i d chromatography pre-
(primary
nitrophenyl acetate
column d e r i v a t i v e .
+
( SNPA)
secondary)
2,4-Di n i t r o - l -
L i q u i d chromatography pre-
f I uorobenzene
column d e r i v a t i v e ,
163
155
clean-up
necessary b e f o r e sample i n j e c t ion.
AmInes
( pr
imary )
5-N,N-dimethylamino-
L i q u i d chromatography pre-
naphthalene-1-sulfonyl
column d e r i v a t i v e ,
chiorlde(DNS c h l o r i d e )
necessary.
DNS c h l o r i d e
Reaction c a r r i e d o u t i n
155
clean-up
a l k a l i n e b u f f e r . L i q u i d chromatography pre-column d e r i v a t l v e .
181
128 P o l l u t a n t type
D e r i v a t i v e and/or
Ref.
Comments
d e r i v a t i v e reagent
Amines
7-Chloro-4-nitro-
L i q u i d chromatography, pre-
(primary and
benzo-2-oxa-1,3-di-
column d e r i v a t i v e .
secondary)
azole(NBD c h l o r i d e )
m i l d l y a l k a l i n e conditions.
Herbicides
Trimethylanilinium
Gas chromatography pre-
hydroxide (TMAH)
column d e r i v a t i v e .
181
Formed under
204
Also on-
column w i t h h i g h temperature I n j e c t i o n port.
Isocyanate monomers
p-Nitrobenzyl-N-n-
L i q u i d chromatography pre-
propylamine hydro-
column d e r i v a t i v e .
chloride(PNBPA)
I l m l t s of 0.7ppb(v/v)toluene
205
Detection
isocyanate i n 2 0 - l i t e r a i r samp i e
Pesticides
BSFTA
.
Gas chromatography pre-column
206,207
derivative.
N-methy I car-
o-Phthaldehyde(OPA1
bamate i n -
L i q u i d chromatography post-
21 3
column d e r i v a t i v e .
sect i c i des. Pheno I s
TMS e t h e r
DNBC
Gas chromatography pre-column
161,
derivative.
208-21 2
L i q u i d chromatography precolumn d e r i v a t i v e ,
155,163
no d e r i v a -
t i v e clean-up necessary b e f o r e injection. 2,6-N it r o p hen y I
L i q u i d chromatography pre-
hydrazone
column d e r i v a t i v e ,
165
no clean-up
necessary.
p-iodobenzenesul-
L i q u i d Chromatography pre-
fonylchloride
column d e r i v a t i v e ,
clean-up
necessary b e f o r e i n j e c t i o n .
165
129 Pol I u t a n t type
Der i v a t i ve and/or
Comments
Ref.
L i q u i d chromatography pre-
155
d e r i v a t l v e reagent
DNS c h l o r i d e
column d e r i v a t i v e ,
clean-up
necessary b e f o r e i n j e c t i o n .
Thlols
NBD c h l o r i d e
L i q u i d chromatography pre-
181
column d e r i v a t i v e .
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E I sev i er, Amsterdam, 1976. J. F. Lawrence (Ed.), Special Issue, D e r i v a t i z a t i o n i n Chromatography, J. Chromatogr. Sci., 17 (1979) 113-176. M. R. Guerin, G. O l e r i c h and W. T. Rainey, Anal. Chem., 56 (1974) 761. A. E. Pierce, S i l y l a t i o n o f Organic Compounds, P i e r c e Chemical Company, Rockford, IL, 1968. P. S. Mason and E. D. Smith, J. Gas Chromatogr., 4 (1966) 398. T. Walle and H. Ehrsson, Acta Pharm. Suec., 7 (1970) 389. F. Karoum, C. F. R. Ruthven and M. Sandler, Biochem. Med., 5 (1971) 505. J. B. Brooks, J. A. L i d d l e and C. C. Alley, Anal. Chem., 47 (1975) 1960. T. H. Jupi I le, Amer. Lab., May (1976) 85. H. D. Durst, M. Milano, E. J. Kikta, S. A. Connelly and E. Grushka, Anal. Chem., 47 (1975) 1797. R. W. Rms, J. Chromatogr. Sci., 14 (1976) 505. J. W. Higgins, J. Chromatogr., 121 (1976) 329. E. Nachtmann and K. W. Budna, J. Chromatogr., 136 (1977) 279. J. W. Vogh, Anal. Chem., 43 (1971) 1618. H. M. Fales and T. Lauakkainen, Anal. Chem. 37 (1965) 955. J. Korolczuk, M. Daniewski and Z. Mielniczuk, J. Chromatogr., 88 (1974) 177. L. J. Papa and L. P. Turner, J. Chromatogr. Sci., 10 (1972) 744. H. K a l I io. R. R. Linko and J. K a i t a t a n t a . J. Chromatoar.. 65 (1972) 355. R. J. Soukup. R. J. Scarpell i n o and E. Danielczik, Anal. Chem., 36 1964) 2255. F. A. F i t z p a t r i c k , M. A. Wynalda and D. G. Kaiser, Anal. Chem., 49 1977) 1032. N. Narasimhachari and P. Vouros, Anal. Biochem.. 45 (1972) 154. S. Baba, J. Chromatogr., 88 (1974) 373. T. Walle, Acta Pharm. Suec, 5 (1968) 367. 0. J. Edwards and K. Blau, Anal. Biochem., 45 (1972) 387. 0 . R. Knapp and S. Krueger, Anal. L e t t . 8 (1975) 603. H. D. Durst, M. Milano, E. S. K i k t a , S. A. Connelly and E. Grushka, Anal. Chem., 47 (1975) 1797. "Fluorotags", Technical B u l l e t i n , Regis Chemical Co., Morton Grove, IL. J. P. Thenot and E. C. Horning, Anal. L e t t . 5, (1972) 519. M. G. Horning, A. M. Moss and-E. C. Horning, Biochem. Biophys. Acta, 148 (1967) 597. E. Anggard and G. Sedval I, Anal. Chem., 41 (1969) 1250. M. Donike, J. Chromatogr.. 78 (1973) 273. P. Cancalon and J. D. Klingman, J. Chromatogr. Sci., 10 (1972) 253. M. Donike, J. Chromatogr., 103 (1974) 91. M. Donike, Chromatographia, 7 (1974) 651. S. B. Matin and M. Worland, J. Pharm. Sci., 61 (1973) 1235. M. G. Horning, A. M. Moss, E. A. Boucher and E. C. Horning, Anal. L e t t . , 1 (1968) 31 1 . J. Vessman, K. H a r t v i g and M. Hoiander, Anal. L e t t . 6 (1973) 699. B. Maume, P. Bournot, J. C. Lhugenot, C. Baron, F. B a r b i e r , G. Maume, M. P r o s t and P. Padieu, Anal. Chem., 45 (1973) 1073. D. D. Clarke, S. WiIk and S. E. G i t l o w i n H. A. Szymanski (Ed.) Biomedical A p p l i c a t i o n s of Gas Chromatography, Plenum Press, New York, 1964, p. 53. J. C. Lhugenot and B. F. Maume, J. Chromatogr. Sci., 12 (1974) 411. F. Karoum. F. Cattabeni. E. Costa, C. R. J. Ruthven and M. Sandler, Anal. Biochem., 47 (1972) 550. E. Gelpi, E. P e r a l t a and J. Segura, J. Chromatogr. Sci., 12 (1974) 701. E. C. Horning, M. A. Horning, W. J. A. VandenHeuvel, B. Holmstedt and C. J. W. Brooks, Anal. Chem., 36 (1964) 1546. D. D. Clarke, S. WiIk and E. Gitlow, J. Gas Chromatog., 4 (1966) 310. P. H a r t v i g and J. Vessman, Anal. L e t t . 7 (1974) 223. P. H a r t v i g and J. Vessman, J. Chromatogr. Sci., 12 (1974) 722. P. Hartvig, W. Handl, J. Vessman and C. M. Smith, Anal. Chem., 48 (1976) 390. H. V. Street, J. Chromatogr., 73 (1972) 73. C. R. C l a r k and M. M. Wells, J. Chromatogr. Sci., 16 (1978) 332. F. S. Tanaka and R. G. Wien, J. Chromatogr., 87 (1973) 85. K. L. Dunlap, R. L. Sandridge and J. K e l l e r . Anal. Chem., 48 (1976) 497.
- -
134 206 207 208 209 21 0 21 1
21 2 21 3 214 21 5 21 6 21 7 218 21 9
S . J. Yu, U. Kilgemazi and L. C. T e r i e r e , J. Agr. Food, 19 (1971) 5. G. T. F I l n t and W. A. Aue, J. Chromatogr., 52 (1970) 478. I . E. Smiley and E. D. Schall, J. Ass. O f f l c . Anal. Chem., 52 (1969) 107. N. E. Hoffman and K. A. Peteranetz, Anal. Lett., 5 (1972) 589. F. K. Kawahara, Anal. Chem., 40 (1968) 1009. I. C. Cohen, J. Norcup, J. H. A. Ruzicka and B. B. Wheals, J. Chromatogr., 44 (1969) 251. H. Ehrsson, J. T. Wal l e and H. B r o t e l l , Acta Pharm. Suec., 8 (1971) 319. J. Muth and J. Giles, A l t e r Chromatogram, 3, No. 2 (1980) 5. R.-D. Penzhorn and W. G. F i I b y , Staub-Relnhalt L u f t , 36 (1976) 205; Anal. Abstr., 33 (1977) 2H14. L. L. Larnparskii and T. J. N e s t r i c k , J. Chromatogr., 156 (1978) 143. C. S . Giam, H. S . Chan, T. F. Hamargren, G. S . Ness and D. L. S t a l I I n g , Anal. Chem., 48 (1978) 78. W. P. Cochrane, J. Chromatogr. Sci., 17 (1979) 124. I. Sunshine, Methodology f o r A n a l y t l c a l Toxicology, CRC Press, West Palm Beach, FL, 1975, p. 116. T. D. Luckey and R. Venugapol, Metal T o x i c i t y I n Mammals, Plenum Press, New York, 1977, Ch. 1 and 5.
135 RELATED READINGS ON SAMPLE TREATMENT
1 2 3
The Gas Phase E x t r a c t i o n and A n a l y s i s o f V o l a t i l e O r g a n i c P o l l u t a n t s I n Water U s i n g a Tenax-GC A d s o r p t i o n Tube. B . I . Brookes, S.H. J i c k e l l s and R . S . N i c o l s o n , J. Assoc. P u b l i c Anal., 16(4)(1978)117-21. Problenis and P i t f a l l s i n Acetaldehyde D e t e r m i n a t i o n s . C.J.P. E r i k s s o n , A l c o h o l . C l i n . Exp. Res., 4 ( 1 ) ( 1 9 8 0 ) 2 2 - 9 . Tenax-GC E x t r a c t i o n Technique f o r Residual P o l y c h l o r i n a t e d B i p h e n y l and P o l y a r o m a t i c Hydrocarbon A n a l y s i s i n B i o d e g r a d a t i o n Assays. F1.P. S h i a r i s , T. S h e r r i l l and G.S. Sa,yler, Appl. E n v i r o n . Microbial 39(1)(1980)165-71. Study o f t h e Composition and Content o f P e t r o l e u m Hydrocarbons i n B a l t i c Sea Water Using C a p i l l a r y Gas Chromatography and I R S p e c t r o p h o t o m e t r y . K. T i k s , S i n t . I s s l e d . B i o l . Swedin., T e z i s y Dokl. Konf. Holodykh Uch., 6 t h ( 1978)91-2. D e t e r m i n a t i o n o f P e t r o l e u m Hydrocarbons i n Tap \dater by Gas Chromatography. V. D u r d o v i c , A c t a Hydrochim. H y d r o b i o l . , 7 ( 5 ) ( 1 9 7 9 ) 5 2 7 . Gas Chromatographic Headspace A n a l y s i s i n Brewing. E. G e i g e r . I n A p p l i e d Headspace Gas Chromatography, B. Kolb, ed., Heyden, London, 1980, pp. 73-9. GC Headspace A n a l y s i s Used i n Government F o o d s t u f f s C o n t r o l - A p p l i c a t i o n s f o r T e s t i n g R e q u i s i t e s . J.J. Doemling. I n A p p l i e d Headspace Gas Chromatography, B. Kolb, ed., Heyden, London, 1980, pp. 171-0. Simple Rapid and S e n s i t i v e Method f o r t h e Simultaneous Q u a n t i t a t i o n o f E t h a n o l and Acetaldehyde i n B i o l o g i c a l M a t e r i a l s Using Head-Space Gas Chromatography. C.L. Mendenhall, J. FlacGee, and E.S. Green, J. Chromatogr., 190( 1 ) (1980)197-200. A n a l y s i s o f Headspace Gases f o r P a r t s Per B i l l i o n C o n c e n t r a t i o n s o f V o l a t i l e Organic Contaniinants i n Water Samples by Gas Chromatography. D.A.J. Murray, E n v i r o n . S c i . Res., (1980)?07-16. t4easurement and A n a l y s i s o f A i r P o l l u t i o n . 6. D e t e r m i n a t i o n o f T r i n i e t h"v l amine i n A i r . S. Sano, Kanagawa-ken T a i k i Osen Chosa Kenkyu Hokoku, 21 (197911 17-23. Acetaldehyde, Methanol, and E t h a n o l A n a l y s i s by tieadspace Gas Chromatography. R.M. Anthony, C.A. Sutheinier and I . Sunshine, J. A n a l . T o x i c o 1 . , 4 ( 1 ) ( 1 9 8 0 ) 43-5. D e t e r m i n a t i o n o f Residual Acetaldehyde i n P o l y ( e t h y 1 e n e t e r e p h t h a l a t e ) B o t t l e s , Preforms and Resins b y Automated Headspace Gas Chromatoqraphv. M. Dong, A.H. DiEdwardo and F. Zitonier, J . Chromatog. S c i . , 1 8 ( 5 ) ( 1 9 3 0 ) 2 4 2 - 6 . A Gas Chromatographic Method f o r t h e A c c u r a t e D e t e r m i n a t i o n o f Low Concent r a t i o n s o f V o l a t i l e S u l f u r Compounds i n A l c o h o l i c Beverages. O.Leppanen, J. Denslow and P. Ronkainen, J . I n s t . Brew., 85(6)(1979)350-3. Gas Chromatographic Head-Space Assay o f Formic A c i d as M e t h y l Forniate i n B i o l o g i c F l u i d s : P o t e n t i a l A p p l i c a t i o n t o Methanol P o i s o n i n g . C . A b o l i n , J.D. McRae, T.N. Tozer and S. T a k k i , Biocheni. Pled. 2 3 ( 2 ) ( l!I80)209-13. D e t e r m i n a t i o n o f Hydrogen Cyanide i n B l o o d U s i n g Gas Chromatography w i t h A l k a l i T h e r m i o n i c D e t e c t i o n . R.W. D a r r , T.L. Capson and F.O. Hileman, Anal. Chem., 52(3)(1980)1379-81. Supplementary Report to"Gas Chromatographic D e t e r m i n a t i o n o f COHb by t h e Use o f a Heated Gas Sampler." K. Yaniamoto, and Y. Yamamoto, Nippon Hoigaku Zasshi, 3 3 ( 6 ) ( 1 9 7 9 ) 7 1 8 - 2 0 . Study o f F l a v o r o f Wines f r o m " T i e r r a de B a r r o s " ( S p a i n ) by Phase Separat i o n Through S a l t A d d i t i o n and Gas L i q u i d Chromatography o f t h e O r g a n i c Phase. J.L. Mesias, J . I . Maynar and I . Mareca, Rev. Agroquim. Tecnol, A1 inient, 20( 2 ) ( 1 980)240-6. Methods o f D e r i v a t i z a t i o n i n A n a l y t i c a l Gas Chromatography: General P r i n c i p l e s and Recent Developments. A . P a n n a t i e r , B. Testa, Pharm. Acta Helv., 5 5 (4)( i g a o ) 100-1 3. Use o f Headspace Gas Chromatosraphic A n a l v s i s f o r D e t e r m i n a t i o n o f V o l a t i l e I m p u r i t i e s i n Polymers. B . V . - I o f f e and T:L. Reznik, Zh. A n a l . Khirn., 3 5 ( 7 ) (19ao)i410-27.
.,
4
5 6 7
a 9
10
11 12 13 14 15 16
17
ia 19
136 20 21 22 23 24 25 26
Enhancement of Electron-Capture D e t e c t i o n o f Chlorocarbons by I o d i n a t i o n . A.J. Watson, G.L. B a l l and D.H. Stedman, Anal. Chem., 53(1)(1901)132-4. I s o l a t i o n and C h a r a c t e r i z a t i o n o f Odorous Components i n S o l i d Swine Manure. A. Yasuhara, and K. Fuwa, A g r i c . B i o l . Chem., 44(10)(1980) 2379-85. Determination o f Halogenated Hydrocarbons i n S i l i c o n Halides w i t h Two GasRath, and Chromatographic Methods and a Comparison o f These Ana1yses.H.J. J. Wimner, Fresenius' Z. Anal. Chem., 303(1)(1980)14-17. Determination o f Cyanides and Thiocyanates i n Water by Headspace Gas Chroma tography w i t h a Nitrogen-Phosphorus Detector. G. Hota, V.R. W i r a g l i a , C. Improta and A. Acampora, J. Chromatogr., 207(1)(1981)47-54. A p p l i c a t i o n o f Headspace Gas Chromatography t o t h e Determination o f C h l o r i nated Hydrocarbons i n Waste Waters. L. Lukacovic, M. f l i k u l a s , A. Vanko and G. Kiss, J. Chromatogr., 207(3)(1981)373-7. Preconcentration f o r Trace A n a l y s i s o f Organic Compounds, F.W. Karasek, R.E. Clement and J.A. Sweetman, Anal. Chem., 53(1981)1050 A. Preconcentration f o r Trace Element Determination i n Aqueous Samples. D. E. Leyden and W. Wegscheider, Anal. Chem., 53(1981)1059A.
CHAPTER 5
THE USE OF GAS CHROMATOGRAPHY I N ENVIRONMENTAL ANALYSES
5.1
INTRODUCTION The preceding chapters have discussed t h e environmental
(Chapter 11,
t h e c r i t e r i a used f o r
sampling
these
environmental
samples,
u s i n g gas
2),
(Chapter
(Chapter 3 ) and t h e sample treatment (Chapter 4 ) .
problem I n general
the
sampling process
We can now discuss t h e analyses o f
chromatography
and
l i q u i d chromatography
(Chapters 5 and 6). There i s a v a s t amount o f s c i e n t i f i c l i t e r a t u r e a v a l l a b l e r e g a r d i n g t h e use o f gas Chromatography chromatography.
for
environmental
analyses,
much more t h a n e x i s t s
There are a number o f reasons f o r t h i s ;
for
liquid
paramount among these i s
t h e f a c t t h a t gas Chromatography has been more r e a d i l y a v a i l a b l e when environmental problems came t o t h e f o r e f r o n t and t h a t t h e m a j o r i t y o f compounds t o be determined are e a s i l y handled by t h e gas chromatographic process. an a i r pol l u t i o n problem e x i s t s .
T h i s i s e s p e c i a l l y t r u e when
To present an a l I - i n c l u s i v e discussion o f analyses
by gas chromatography would r e s u l t i n a very long monograph i t s e l f .
Thus,
we s h a l l
h i g h l i g h t t h i s area o f a n a l y s i s and f u r n i s h many e a s i l y o b t a i n a b l e references.
To
condense many of these references we W I I I make use o f t a b l e s t o summarize t h e s a l i e n t features of the a r t i c l e s .
5.2 STANDARDS AND CALIBRATION We
have
presented
in
components which are a v a i l a b l e .
Chapter
2
necessary procedure t o have q u a n t l t a t l v e system.
Meanlngful
sources
information
Information w i l l r e s u l t
r e g a r d i n g t h e volume o f sample,
of
many
reference
(standards)
C a l i b r a t i o n by use o f these standard components i s a for
any environmental
i f r e l i a b l e information
volume o f standard s o l u t i o n ,
sample
i s given
and f l o w measurements
f o r gas and l i q u i d samples. Perhaps one o f t h e most d i f f l c u l t aspects o f c a l i b r a t i o n and q u a n t i f i c a t i o n i s being able t o express t h e small c o n c e n t r a t i o n s found i n environmental samples.
Table
5.1 summarizes many o f t h e mass-volume o r volume-volume r e l a t i o n s encountered i n t h e area o f t h e a n a l y t i c a l chemistry o f environmental systems. The p r e p a r a t i o n o f standard aqueous s o l u t i o n s
I s best performed by s t a r t i n g
w l t h a concentrated s o l u t i o n and making t h e a p p r o p r i a t e d i l u t i o n s t o f u r n i s h l e s s concentrated standards.
The choice o f
p r e d i c a t e d upon t h e t h e o r y t h a t must be mlnimlzed.
containers
for
these
solutions
should be
loss o f s o l u t e and contamination from t h e c o n t a i n e r
These two g o a l s can be achieved by using clean g l a s s v o l u m e t r i c
138 f l a s k s and/or v i a l s w i t h e i t h e r standard tapered stoppers o r screw-on l i d s l i n e d w l t h T e f l o n (PTFE) o r aluminum f o i l . t o r or freezer. when needed.
Once prepared, they should be s t o r e d i n a r e f r i g e r a -
Very d i l u t e standard s o l u t i o n s (10 ppm o r l e s s ) a r e b e s t prepared
Prolonged storage of very d i l u t e standards r a i s e s questions r e g a r d i n g
their stability.
Adsorption on w a l l s o f c o n t a i n e r s and/or loss by v o l a t l l i z a t i o n a r e
t h e most frequent causes o f t h i s decreased concentration.
TABLE 5.1 Mass-volume and volume-volume r e l a t i o n s h i p s f o r environmental samples.
I.
Mass-vol ume mg/a = 1 ppm
= 1000 ppb
ug/ml = 1 ppm
= 1000 ppb
ug/5.0 m l = 0.2 ppm = 200 ppb ,,g/IO.O
m l = 0.10 ppm = 100 ppb
pg/20.0 m l = 0.05 ppm = 50 ppb ug/IOO.O m l = 0.01 ppm = 10 ppb (grams/1000 m l
Equation f o r c a l c u l a t i o n : mg/ml = 1000 ppm = 1,000,000
) x
lo6 = ppm
ppb
II. Volume-volume pl/ml = 1000 ppm = lo6 ppb = 0.1% ml = 100 pprn = ppb = 0.01% ~1/10.0 pl/lOO.O ml = 10 ppm = lo' ppb = 0.001% pl/1000.0ml = 1 ppm = lo3 ppb = 0.0001% 100pl/lO.Oml = 10,000ppm = lo7 ppb = 1.0% lOpl/l.Oml = 10,000ppm= lo7 ppb= 1.0%
lo5
Equation for calculation: (Ctl/ml) X
lo6 = ppm
I l l . Inter-relationships
%
PPm
100.00 10.00
I .oo 0.1 0.01 0.001 0.0001 0.00001 0.000001 0.0000001
rng/100 m l
PPb
I , 000,000 000 10,000 1,000 100 10 0.1 0.01 0.001
UNIT
1 00,000 10,000
too,
I
gluI
I , 000 100 10 1 1 ,000
100 10 1
0. I 0.01 0.001 0.0001
10-6
10-7 10-8 10-9 10-10 10-11 10-12
u9
ng
P9
139 Preparation of water s o l v e n t .
aqueous standards p r e s e n t s another
T h i s "pure"
w a t e r must be f r e e o f
( v o l a t i l e as w e l l as n o n - v o l a t l l e ) .
I n many cases,
problem,
that
of
rtpurelf
s o l u b l e o r g a n i c substances
r e g u l a r d i s t i l l e d water
i s not
adequate and must be p u r i f i e d f u r t h e r . (1) V o l a t i l e contaminants. I f o n l y v o l a t i l e contaminants a r e present, t h e Ifpure" water may be prepared by b o i l i n g t h e water i n a clean atmosphere. Standards prepared i n Itpure" d i s t i I l e d water should have no gas phase above t h e I i q u i d phase. The standard s o l u t i o n s should completely f i l l t h e c o n t a i n e r . ( 2 ) N o n - v o l a t i l e contaminants. These contaminants may be removed by u s i n g t h e sampling techniques discussed I n Chapter 3. Adsorbents used can be Porapak Q o r Bondapak ( r e f . 1 ) . Amberlite XAD-2 r e s i n o r a c t i v a t e d charcoal ( r e f . 2 and 3 ) and Tenax GC ( r e f . 4 ) . Creed ( r e f . 1 ) c a u t i o n s t h a t " p u r e " w a t e r made by t h e s e techniques should n o t be stored longer than t h r e e days. A f t e r t h e f i r s t couple o f days, t h e blank c o r r e c t i o n begins t o increase. ( 3 ) Non-aqueous solvents. I t has been t h e authors' experience t h a t l a r g e volumes of "clean" s o l v e n t s ( > 500 m l ) should be s t o r e d i n another room t h a n t h e laboratory. Only small volumes (ca. 100 m l ) should be k e p t i n t h e l a b o r a t o r y . R e f i l l i n g o f t h e l a b o r a t o r y supply should be performed i n t h e storage area. A good philosophy f o r s o l v e n t s used i n t r a c e environmental a n a l y s i s i s t h a t no s o l v e n t should be considered pure. Acetone and methanol can be p u r i f i e d by d i s t i l l a t i o n i n a glass apparatus, whereas n-pentane, n-hexane and isooctane should be d i s t i l l e d a f t e r s u l f o n a t i o n o f t h e aromatic i m p u r i t i e s and n i t r a t i o n ( r e f . 5).
R e s t r i c t i o n s placed on s o l v e n t s and c o n t a i n e r s are more s t r i n g e n t t h a n those placed on t h e p u r i t y o f t h e standards.
Standard compounds need be no h i g h e r p u r i t y
than 99% f o r environmental t r a c e a n a l y s i s . S o l u b i l i t y o f many organic compounds (e.g.,
hydrocarbons) i n water i s very low
and aqueous standard s o l u t i o n s may have t o be prepared by u s i n g an o r g a n i c s o l v e n t which i s s o l u b l e i n water. e x t r a c t i o n of
the
A disadvantage t o t h i s technique i s t h a t ,
aqueous s o l u t i o n ,
a
large quantity of
i n subsequent
t h e organic
solvent
is
c a r r i e d through and may overlap s o l u t e peaks of i n t e r e s t i n t h e chromatogram. A i r o r gas samples o f f e r a unique a p p l i c a t i o n f o r gas chromatography.
s o l v e n t here i s a i r and blanks must be made f r o m "zero a i r . " appeared
i n T i t l e 40 of
t h e U.S.
Federal Regulations,
P a r t 86 o f
Control
P o l l u t i o n f o r New M o t o r V e h i c l e s and New M o t o r V e h i c l e E n g i n e s , requirement
for
the
flame
ionization
detector
(FID)
and
other
TABLE 5 . 2 Federal R e g i s t e r 33(108),
< < <
columns.
However, the
number of theoretlcal 1.5 pm).
The large-bore
can accommodate stationary phase fiims u p t o 2.0-2.5
and thus are able to be used with direct
Injection techniques,
larger sample
These added advantages do bring sizes, and a larger sample concentration range. 3 disadvantages: lower column efficiency (ca. 10 plates per meter) and longer analysis times.
The outstanding advantage of capillary columns versus packed columns
is that the choice of stationary phases becomes less of a problem because their efficiency is so high.
This translates into the fact that a smaller number of phases
will be necessary, 1.e..
a nonpolar phase (e.g.,
SE-30 or OV-101), a polar phase
(e.g., Carbowax ZOM), and an Intermediate polar phase (e.g., OV-17). This does not imply that packed columns will disappear from the laboratory. They will always have a place for the separation and analysis of samples containing
10 components, low molecular-weight gases, preparative work and separations coupled with detectors (e.g., infrared or nuclear magnetic resonance) for low sensitivity. The reader i s referred to a number of excellent books concerning capillary columns in order of their publication:
Open Tubular Columns in Gas Chromatography b y
154 51 1,
Ettre (ref.
Gaschromatographie,
Chromatography by Freeman
(ref.
by Schmberg ( r e f .
53)
521,
High R e s o l u t l o n Gas
and Gas Chromatography w i t h Glass C a p i l l a r y
Columns by Jennings ( r e f . 54). An important concern i n c a p i l l a r y chromatography i s q u a n t i t a t i o n . most common mode o f sample i n t r o d u c t i o n onto c a p i l l a r y columns which a s y r i n g e - i n j e c t e d column and a vent, usually
seen
I s w i t h valves
wide
boiling-point
range
samples
T h i s problem i s
and/or
polar
compounds.
increasing t h e I n l e t temperature may help i n some cases, b u t it i s n o t a c u r e - a l l t h i s problem.
in
sample i s dynamically s p l i t i n a heated tube between t h e
d i s c r i m i n a t i o n o f sample components can occur.
with
Because t h e
The c o l d on-column
for
I n j e c t i o n i n t o an unheated i n j e c t i o n p o r t has been
demonstrated t o be i n d l s c r i m i n a t e as f a r as t h e sample components are concerned ( r e f . 54A).
A s p e c i a l l y designed i n l e t f o r c o l d on-column
c o m m e r c i a l l y a v a i l a b l e from H e w l e t t P a c k a r d Co., Strumentazlone ( r e f s . 548 and 54C)). method cannot be automated.
i n j e c t i o n i s needed. Avondale,
(This i s
PA and C a r l o E r b a
U n f o r t u n a t e l y , t h i s c o l d on-column
injection
(See Appendix 1 1 . )
5.5 DETECTION OF SAMPLE COMPONENTS A number o f d e t e c t o r s a r e a v a i l a b l e t o t h e environmental f o r use i n gas chromatography ( r e f s . 55-57).
a n a l y t i c a l chemist
The two most w i d e l y used d e t e c t o r s a r e
(FID) and t h e e l e c t r o n c a p t u r e d e t e c t o r
t h e flame i o n i z a t i o n detector
(ECD).
flame I o n i z a t i o n d e t e c t o r destroys t h e sample d u r i n g i t s measuring process;
a predetermined percentage o r r a t i o o f t h e column
by use o f gas stream s p l i t t e r , effluent
can
Identification.
be
diverted
The
however,
away
from
the
detector
for
further
study
and/or
I n t e r f a c i n g t h e gas chrcinatograph w i t h a mass spectrometer ( r e f . 58)
provides a means o f both i d e n t i f i c a t i o n and q u a n t i f i c a t i o n . To o b t a i n good gas chromatography-mass necessary techniques,
to
optimize
the
gas
spectrometry (GC-MS)
chromatographic
and t h e i n t e r f a c e techniques.
method,
operation,
mass
As a f i r s t e s t i m a t i o n ,
pumped mass spectrometer can r e c e i v e 1 cm3 atm/min (1.3 x c a r r i e r e f f l u e n t gas.
the
it i s
spectrometric
a differentially
l i t e r Torr/sec) o f the
The mass spectrameter can accomodate t h e c a r r i e r e f f l u e n t
from e i t h e r packed o r open-tubular w i t h a gas chromatographic-mass
columns.
To achieve good q u a l i t a t i v e a n a l y s i s
spectrometric system,
pure chemicals a r e necessary.
The best gas chromatographic-mass spectrometric d a t a come from chromatography systems which have high column e f f i c i e n c y p r i o r t o t h e mass s p e c t r o m e t r i c a n a l y s i s . high column e f f i c i e n c y i s not always necessary because unresolved peaks can, cases, be I d e n t i f i e d by GCMS. troublesome using t h i s
technique,
especially
if
the
compounds being e l u t e d
chemically s i m i l a r ( a l c o h o l s and aldehydes a r e t h e most troublesome). probably
react
i n many
The t a i l i n g of peaks from p o l a r compounds can be very
chemically with t h e adsorption s i t e s o f
whereas non-ionlc s u r f a c t a n t s probably f u n c t i o n more as w e t t i n g agents.
are
This problem
may be m i n i m i z e d by a d d i n g s u r f a c t a n t s t o t h e l i q u i d s t a t i o n a r y phase. surfactants
This
Ionic
t h e column,
Some common
155
surfactants used are: lgepal CO880, Alkaterge T, and Span 20. The carrier gas used in GC-MS must ( 1 ) be chemically inert, (24 not interfere with the mass spectrometric pattern, ( 3 ) enable enrichment of the sample components in the gas stream, and ( 4 ) not interfere with the total ion detection. The most commonly used carriers in GC-MS are helium, hydrogen, and nitrogen. Helium is the best. Hydrogen interferes with total ion detection and nitrogen does not always enrich the sample components in the carrier stream, interferes with the total ion detection, and interferes with mass spectral patterns' in the low mass range. Additional qualitative information may be obtained when specific chromatographic detectors are used in combination with the mass spectrometer. For example, a flame photometric detector for compounds containing phorphorus and/or sulfur, the coulometric detector for compounds containing sulfur, nitrogen and/or halogens, the thermionic detector for compounds containing phosphorous, halogen and/or nitrogen, and the electron capture detector for compounds containing halogen and/or sulfur as well as functional groups, i.e., conjugated carbonyls, di- and trisuifides, and nitriles. Gas chromatographic detectors may be placed in two categories: ( 1 1 detector response is concentration-dependent, or ( 2 ) mass-flow-rate dependent. The sensitivity is the ability of the detector to respond to compounds entering its environment. The sensitivity of concentration-dependent detectors is expressed as: Sensitivity = (peak area x flow-rate)/sample weight 3
= (mV x cm /min)/mg
(5.17) (5.18)
The sensitivity of mass-flow-rate dependent detectors is expressed as: Sensitivity = peak area/sample weight =
A/g
(5.19) (5.20)
The lower limit of detection (LLD) is the smallest amount of sample which.will cause a measurable signal (i.e., twice the noise) over the noise signal. This is also known as the minimum detectable limit (MDL) or minimum detectable quantity (MDQ). Detector specificity is the ratio of the detector response of a contaminant (interfering substance) to that of the desired component. Detector linearity is the range over which the detector maintains constant sensitivity to increasing concentration of a specific component, i.e., it is the range over which the response is directly proportional to the mass flow-rate or the concentration of a component. If a larger quantity passes through the detector the output is no longer proportional and the detector is "saturated." The component peak in the non-I inear range wi I I be rounded at the apex. Detectors are also described by their response time (time necessary for the detector signal to reach 63% of its true value). A recorder which has a response time slower than that of the detector limits the detector response time.
156 Table 5.6 sumnarizes some o f t h e more w i d e l y used detectors.
The a n a l y t i c a l
c h e m i s t must choose t h e d e t e c t o r on t h e b a s i s o f t h e t y p e o f compound t o be q u a n t i f l e d and i t s c o n c e n t r a t i o n range i n t h e samples. TABLE 5.6 Widely used gas chromatographic d e t e c t o r s
Type
Components detectable
Linearity
Flame i o n i z a t i o n
Organic
5 x
( F ID)
compounds
7 x
E I e c t r o n capture
Halogenated,
10' -1 OL
(ECD)
oxygenated
Response category
lo6lo7
*
MFR*
Minimum detectable Iimits
10-l'
Samp I e compound
g(C)/sec.
Propane
moles/cm3
Lindane
-
C**
compounds Flame photometric
Phosphorous
5 x 102(S) MFR*
and s u l f u r
1 x 103(P)
10-l' g(S)/sec 2 x 10-1'g
Thiophene
(FPD)
compounds
l o g / l o g scale
(P)/sec
phosphate
Phorphorous
lo3
5
Azobenzene
Thermionic/alkal I
MFR*
10-l~
containing
5
compounds
(P)/sec
1 o4
Organic,
-
(N)/sec
flame (TID)/(AFID) and n i t r o g e n
Thermal conducti-
Tr i b u t y I
C**
Tr 1buty I
10-l~
5 x 10-l'
-
phosphate g/ml
Propane
1 norgan Ic,
v l t y (TCD)
compounds *Mass f l o w r a t e dependent,
(mv/mg/sec)
**
Concentration dependent,
(mv/mg/ml) -
Permanent gases may be detected i n t h e ppb range w i t h t h e use o f a h e l i u m detector.
A beta-source
(250 mC) e x c i t e s t h e helium atoms which i n t u r n e x c i t e
molecules having an i o n i z a t i o n p o t e n t l a l lower than t h a t of helium.
Representative
If t h e gases t o be determined a r e i n t h e ppb range, a 400 V e l e c t r i c f i e l d w i l l y i e l d measurable i o n c u r r e n t s o f about 4 x i o n i z a t i o n p o t e n t i a l s a r e shown i n Table 5.7.
10' A.
The helium d e t e c t o r r e q u i r e s h i g h l y p u r i f i e d h e l i u m for t h e c a r r i e r gas and
has a s e n s i t i v i t y
h i g h e r than t h e thermal
ionization detector (FID).
conductivity c e l l
(TCD) o r
the
flame
157 TABLE 5 . 7 I o n i z a t i o n p o t e n t i a l s (eV) o f s e l e c t e d gases
10.4
H2S O2 s02
co2
15.5
N2
13.1
co
14.5
CH4
12.5
15.6
14.1
H2 Ar
15.7
14.4
Ne
21.5
He
24.5
5.6 QUALITATIVE AND QUANTITATIVE INFORMATION
The realm o f q u a l i t a t i v e and q u a n t i t a t i v e a n a l y s i s i n GC i s much broader than t h e 'luser''
o f chromatography r e a l l z e s .
To t h e a n a l y t i c a l chemist these two d l v l s l o n s
o f a n a l y s l s are v e r y s p e c i f i c categories.
I n t h e general sense o f t h e word,
qualita-
t l v e denotes t h e k i n d s o f components present, whereas q u a n t i t a t i v e conveys t h e amount of
each
component
chromatographic
that
Is
present.
Obtaining
system i s a s t r a l g h t f o r w a r d
quantitative
data
from
process once t h e chromatographer
a has
e s t a b l i s h e d accurate q u a l i t a t i v e data. There
I s no e r r o r - p r o o f
solely from t h e chromatogram.
way o f
obtaining
reliable
qualitative
information
There a r e a number o f very b a s i c reasons f o r t h i s .
( 1 ) The number o f peaks present from an unknown sample i s no guarantee o f t h e number
of components I n t h e sample. t i m e ( o r volume)
Several components c o u l d have t h e i d e n t l c a l r e t e n t l o n
under t h e c o n d i t i o n s t h a t t h e .separation
( 2 ) The
was obtalned.
assumption t h a t one makes i s t h a t t h e e n t l r e sample was t r a n s p o r t e d through t h e column.
P a r t o f t h e sample may be deposlted a t t h e t o p o f t h e column and never moved
down t h e column. s t a t l o n a r y phase,
( 3 ) Improper c o n d l t i o n s ( i . e . , etc.)
temperature,
pressure,
column
may have been used and e i t h e r p y r o l y s i s o f t h e sample
components o r r e a c t i o n o f t h e sample components w i t h t h e column r e s u l t e d .
What t h i s
means t o t h e a n a l y t i c a l chemlst i s t h a t each peak must correspond t o a s i n g l e sample component.
The authors wish t o emphasize t h i s p o i n t because we have seen many
persons come t o t h e wrong c o n c l u s i o n uslng t h e chromatogram as t h e i r s o l e source o f information. component,
I f t h e chromatographer succeeded I n s e p a r a t i n g each and every sample there
i s no absolute method o f e s t a b l i s h i n g e x a c t l y t h e correspondence
between peaks and sample components from r e t e n t l o n data alone. 5.6.1 Q u a l i t a t i v e a n a l y s l s by qas chromatography
Q u a l l t a t i v e data I n gas chromatography gories of
Information:
(1)
a r e o b t a l n e d from two general c a t e -
I n f o r m a t i o n o b t a i n e d from r e t e n t i o n data and ( 2 )
formation obtalned by employing a u x l l l a r y technlques.
In-
R e t e n t i o n 'data a r e a f u n c t i o n
o f t h e p a r t l t l o n c o e f f i c i e n t ( a thermodynamic f u n c t i o n ) ;
however,
t h e y may n o t be
158 t o o i n f o r m a t i v e unless t h e component make-up of a sample i s known o r t h e components a r e a l l members of an homologous series.
The use of
r e t e n t i o n data t o
identify
components of a complete unknown sample leaves much t o be desired. 5.6.1.1
Retention data.
Retention data i n terms o f tlme,
i.e.,
retention time
It
(tR) and adjusted r e t e n t l o n t i m e (tIR) a r e t o o dependent upon column parameters. i s b e t t e r t o use r e t e n t l o n volume,
VR. (5.21)
VR = tRFc
adjusted- r e t e n t i o n volume, V I R V I R = (tR- t M ) F c
n e t r e t e n t i o n volumn, V
VN = j V l
(5.22)
N
(5.23)
R
o r s p e c i f i c r e t e n t i o n volume, V
9 (5.24)
where Fc = volumetric f l o w r a t e of mobile phase a t column o u t l e t i n ml/mln.,
tM= r e t e n t i o n t i m e of an unretained peak, j = p r e s s u r e g r a d i e n t c o r r e c t i o n f a c t o r = 3/2 ((pl/po)2-l)/((pi/po)3-l
);
pi
and po a r e t h e mobile phase i n l e t and o u t l e t pressures; T = column temperature
(OK),
and
wL = welght of s t a t i o n a r y phase i n column,
because t h e s e p a r a m e t e r s a r e l e s s dependent upon column c o n d i t i o n s . r e l i a b l e term f o r q u a l i t a t i v e a n a l y s i s I s r e l a t i v e r e n t e n t l o n volume, r
The more
a/b'
because one i s canparing t h e r e t e n t i o n volume of a component t o t h e r e t e n t i o n volume o f a s t a n d a r d s u b s t a n c e under t h e same column c o n d i t i o n s . standard I s dependent upon ( 1 )
i t s a v a l l a b i l l t y and ( 2 )
other components I n t h e sample (should be half-way
The c h o i c e
of t h e
I t s r e t e n t i o n compared t o
i n t h e range o f r e t e n t i o n volumes
being compared). Additional qualitative informatlon may be obtained If one separates the sample components on two columns of different polarity and plots the log adjusted retention volume ( V f R ) versus the reciprocal of absolute column temperature. The slopes of the data lines from each column usually are different and even the order of elution of some components change. 5.6.1.2 Retention Index.
The retention index of Kovats (refs. 59-62) compares
retention data to a series of standards, rather than one compound standard. series
of
standards
was
the
even-carbon-atom
n-alkanes
and
their
index,
definition, was 100 times the number of carbon atoms in the molecule, i.e., was 200;
hexane was 600, etc.
The
by
ethane
This index system is described mathematically as
I = lOON t 100( logVIR(A)-logVIR(N)I / ( logVIR(n)-logVIR(N))
(5.26)
where A = unknown component;
N and n
= the smaller and larger n-alkanes which bracket the unknown component
A.
The n-alkanes which are chosen should give peaks compIetely separated from the sample component.
Hupe (ref. 63) has constructed a nomogram from which one may calculate I
values without doing the lengthy calculations. Polar compounds display greater temperature dependence than do non polar compounds on the Kovats' index scale.
When reporting temperature dependent data it
is useful to give the temperature coefficient of the I value In reference to a 10' C temperature change plus the temperature range covered, e.g., (5.27) Some general guidelines for using thls index from data collected on a single stationary phase are:
( 1 ) as the number of carbon atoms increases in an homologous
series, the retention index Increases b y 100 units,
( 2 ) the same functional groups
on compounds having similar structures increase the retention extent,
index to the same
( 3 ) a simple relationship exists between boillng point and retention index
on a nonpolar phase (thus index systems can be used to predict boillng points of unknown components) and the difference between the retention indlces of
isomeric
compounds can be approximated by the difference in boiling points ( 6 1 = 56 b.p.). Guiochon (ref. 64) extended Kovatsl work on the index system to molecular structure and concluded that
( 1 ) I values of nonpolar compounds are usually constant
using any stationary phase,
(2) I values for some components on different polarlty
phases are characteristic of molecular structure, same on nonpolar stationary phases, and
( 3 ) I value of any compound is the
(4) the presence of unsaturatlon sites,
functional groups and rings in a compound add incremental values to the basic
160 retention Index. The Kovats retention index Is more accurate than other retention data parameters, provided the support material causes no adsorption effects with polar compounds, the column temperature and the mobile phase flow rate are controlled, and the sample size is in the linear portion of the partition isotherm.
Reproducibility of
retention indices are very good for nonpolar compounds and within 2% for polar compounds. 5.6.1.3 Auxiliary techniques. The use of retention data does not give the analytical chemist unequivocal identification of sample components so other techniques must be employed.
This additional
information may be obtained from
modification of the chromatographic system per se or b y employing measurements of detection other than the usual chromatographic detectors.
(i)
Chromatographic measurements may be obtained b y
detector or a combination of detectors or As pointed out in Section 5.5,
using a specific
(1)
( 2 ) using other chromatographic systems.
various detectors respond t o certain types of
compounds or functional groups, e.g.,
electron capture detectors for compounds con-
taining halogens, the flame photometric detector for phosphorus- and sulfur-contain-
ing molecules, and radioactive detectors f o r the detection of labeled compounds (ref. Additional information may be obtained b y doing a preliminary separation using liquid chromatography (Chapter 6 and ref. 66), thin-layer chromatography (ref. 6 7 ) or paper chromatography (ref. 68). Golovkin et al. (ref. 69) combined retention indices and selective detectors for the quaiitatlve identification of halogen, phosphorus and
65).
sulfur containing pestlcides. ( i i ) Qualitative Information may be obtained b y combining other detection tech-
niques than the usual chromatographic detectors.
The combination of GC and MS is a
widely used system for qualitatively identifying components in environmental samples (ref. 70). Dioxin in tissue has been determined b y the combination of capillary GC and atmospheric pressure negative chemical ionization (ref. 71);
mirex pollution in
water has been assayed b y using capillary GC-MS (ref. 721, and the light fractions in tar have been identified using GC-MS (ref. 73).
Infrared spectro-chemical detection
was used by Baranski et al. (ref. 74) to study the catalytic properties of NaHY zeolites, whereas cresols in work area air were detected b y 75).
Vistocco and
Beggio (ref.
Sulfur compounds in flue gases were identified a n d determined b y non-flame,
source-induced sulfur fluorescent detectors (ref. 76) and Chow and Karmen (ref. 77) Derivatives were determined primary amines b y on-line fluorescence measurements. made of amino acids (oxazolidinones) and measured b y flame ionization detection (ref. 78).
Pannatier and Testa (ref. 79) have written a review article about the use of
derivatives to aid in the identification of components in unknown mixtures. ancillary technique which may be mmbined with GC is that of pyrolysis.
Another
Kessel'man
and Ogloblina (ref. 80) did a preliminary separation of organic compounds with thirrlayer chromatography and then pyrolyzed the spots followed by GC.
Eight Bacillus
161 microorganisms i n c e l l s were i d e n t i f i e d by p y r o l y s i s GC by Chou ( r e f . 81). 5.6.2
Q u a n t i t a t i v e a n a l y s i s by gas chromatography Q u a n t i t a t i v e GC i s concerned w i t h how much o f
sample.
a component
i s present
in a
For a more d e t a i l e d coverage of t h e v a r i o u s techniques o f obta4ning q u a n t i -
t a t i v e data, t h e reader i s r e f e r r e d t o t h e e x c e l l e n t chapter by Debbrecht ( r e f .
82)
and t h e book by Novak ( r e f . 83).
All
t h e commonly used d e t e c t o r s i n GC (TCD,
differential
chromatogram,
flows through t h e c e l l
FIO,
ECD,
FPD,
etc.)
produce a
I f c o n d i t i o n s a r e i d e a l and t h e column e f f l u e n t
i.e.,
uniformly,
one o b t a i n s peaks which a r e gaussian
i n shape.
These may be mathematically described by eqn. 5.28:
n = 0.5m
-
-1/2 (dt)
i2/4Dt
(5.28)
where n = c o n c e n t r a t i o n o f gas molecules;
m = t o t a l quantity of d i f f u s i n g material; n = constant = 3.1416;
D = diffusion coefficient; t
time; and
i = distance molecules d i f f u s e .
The s i z e o f t h e peak i s p r o p o r t i o n a l t o t h e amount o f component I n t h e sample.
i f t h i s i s true,
t h e peak area and/or t h e peak h e i g h t w i l l
be p r o p o r t i o n a l t o t h e
Peak h e i g h t I s p r o p o r t i o n a l t o the amount
amount o f t h e component causing t h e peak.
o f a component c o n t r i b u t i n g t o t h e peak i f t h e r e !s no change i n t h e system which w i i i cause a change i n t h e peak w i d t h when comparing a sample t o a standard.
parameters may I n f l u e n c e t h e peak width:
( 1 ) temperature,
mobile phase, ( 3 ) sample I n j e c t i o n , and ( 4 ) column overload.
To m a i n t a i n an accuracy
o f 1 % i n t h e a n a l y s i s t h e temperature must be c o n t r o l l e d t o w i t h i n +0.3OC,
-+0.loC
and t h e f l o w r a t e c o n t r o l l e d t o w i t h i n 20.1%.
an e f f e c t on peak width;
are a f f e c t e d t h e l e a s t .
preferably
Poor sample i n j e c t i o n w i l l have
peaks which emerge q u i c k l y (i.e.,
volume) are a f f e c t e d t h e most.
Four
( 2 ) flow r a t e of the
1-2 t i m e s t h e hold-up
Peaks which a r e a t l e a s t t e n t i m e s t h e hold-up volume
Component adsorption on t h e column a f f e c t s peak w i d t h t h e
most when t h e c o n c e n t r a t i o n i s low.
When t o o l a r g e a sample i s I n j e c t e d ,
the
s t a t i o n a r y phase becomes saturated, which broadens t h e peak and consequently reduces peak h e i g h t . The peak h e i g h t o r area may be obtained by manual methods o r by use o f integrator. measurements.
Fig.
A
5.1
Illustrates
the
constructions
necessary
for
an
manual
l i n e AB i s drawn along t h e base o f t h e peak so t h a t it connects both
sides o f t h e peak t o t h e baseline. maximum and labeled CD.
A
perpendicular t o l i n e
AB
I s drawn from t h e peak
A t a p o i n t halfway up t h e p e r p e n d i c u l a r CO,
i s drawn p a r a l l e l t o t h e base
AB.
This l a s t
another
l i n e EF
l i n e i s known as t h e peak w i d t h a t
162 half-height.
The product o f CD and EF i s t h e area of t h e peak.
F i g . 5.1 Lines and p o i n t s o f c o n s t r u c t i o n f o r peak s i z e measurements. I n t e g r a t o r s r e c e i v e t h e d e t e c t o r response s i g n a l and i n t e g r a t e I t d i r e c t l y on a t i m e b a s i s ( p r o v i d e d t h e number o f c o u n t s p e r u n i t t i m e a r e p r o p o r t i o n a l
to
d e t e c t o r response) which g i v e s a simple r e l a t i o n s h i p between t h e t o t a l number of peak counts and t h e peak area.
T h i s can be shown mathematically by eqn. 5 . 2 9 :
n i = KA,B-'(db/dt)-' where
(5.29)
ni = t o t a l number o f i n t e g r a t o r counts;
K = p r o p o r t i o n a l i t y constant; B = recorder constant db/dt = recorder c h a r t speed; and A, = peak area. Returning t o F i g .
5.1
one sees t h a t t h e r e are t h r e e measurements which are
p r o p o r t i o n a l t o t h e amount o f a component from t h e chromatographic peak: ( 1 ) t h e peak height, CD;
( 2 ) t h e peak area measured by t h e product o f peak h e i g h t CD and t h e peak w i d t h a t h a i f - h e i g h t EF, and
( 3 ) t h e peak area measured by t r i a n g u l a t i o n , GHI, which i s GD times one-half
t h e base H I .
i.e.,
t h e area of t h e t r i a n g l e
163 Once t h e chromatogram has been i n t e r p r e t e d by use o f peak h e i g h t o r peak area, i t i s necessary t o use some S t a n d a r d i z a t i o n technique t o r e l a t e one o r b o t h o f these
measurements t o standards. ization.
We s h a l l
Alternatively, analysis.
we
There are several
techniques
n o t discuss each one and/or shal I
present
t h e more
wldely
More d e t a i l may be obtained from r e f s .
a r t i c l e i n American Laboratory by I. G.
the variants o f used methods
for
environmental
82 and 83 or from a t h r e e - p a r t
Young ( r e f . 8 4 ) .
from t h e column separated from a l l components o f t h e sample,
( 1 ) elutes
( 2 ) elutes close t o the
( 3 ) has a s i m i l a r f u n c t i o n a l g r o u p ( s ) t o t h a t o f t h e
( 4 ) i s s t a b l e and u n r e a c t i v e w i t h sample components,
desired component,
standard-
t h e techniques.
for
A standard substance i s chosen t h a t
( I ) Internal standardization.
desired component under study,
available
or (5) i s
n o n - v o l a t i l e enough t h a t standard s o l u t i o n s may be made and s t o r e d f o r long p e r i o d s o f time.
Several standard s o l u t i o n s c o n t a i n i n g known weights o f t h e chosen standard
and d e s i r e d component t o be s t u d l e d should be prepared. for
these standard s o l u t i o n s should be
desired component
i n t h e sample,
The weight range chosen must
A p l o t o f weight r a t i o versus area r a t i o
not overload t h e column or t h e d e t e c t o r .
linear.
To determine t h e amount o f
a known weight o f
the standard
i s added.
the The
response f a c t o r , F, o f t h e desired component i s c a l c u l a t e d from any o f t h e standard s o l u t i o n s prepared and t h e f o l l o w i n g equation:
F =
weight o f d e s i r e d component/weight o f standard peak area o f desired canponent/peak area o f standard
The weight o f t h e desired component, Wc,
(5.30)
i n t h e unknown can then be c a l c u l a t e d using
eqn. 5.31:
Wc
= (Ac x W i ) / ( A i
where W.
x F)
(5.31 1
and A . are t h e weight and peak area o f I n t e r n a l standard i n t h e sample,
i s t h e peak area o f t h e desired component,
AC
and F I s t h e response f a c t o r o f d e s i r e d
component ( c a l c u l a t e d from eqn. 5.30). ( i i ) External standardization.
A c a l i b r a t i o n c u r v e 1s p r e p a r e d ( u s i n g
i d e n t i c a l c o n d i t i o n s as t h e sample) f o r each substance i n t h e sample which i s t o be quantitated.
This curve may be ( 1 ) peak area versus c o n c e n t r a t i o n o r ( 2 ) peak h e i g h t
versus concentration.
When t h e sample i s run,
t h e peak h e i g h t o r peak area o f t h e
substances t o be q u a n t i t a t e d I s compared t o t h e c a l i b r a t i o n curves. ( i i i ) Internal normalization.
To use I n t e r n a l normalization,
sample component must produce i t s own i n d i v i d u a l peak.
each and every
One o f t h e sample components
may be used as t h e reference, or another component which i s separated from a l l sample components may be used. each component.
A standard sample
i s made up c o n t a i n i n g known weights o f
The r a t i o o f peak area ( o r peak h e i g h t ) o f each substance t o a c t u a l
164 weight percent i n Standard sample i s c a l c u l a t e d f o r each component. component
F,
i s assigned a response f a c t o r ,
of
The r e f e r e n c e
100 ( r e f .
unity or
85),
and t h e
response f a c t o r o f t h e o t h e r components i n t h e standard are c a l c u l a t e d by d i v i d i n g t h e r a t l o of each component by t h e r a t i o of t h e r e f e r e n c e component. i l l u s t r a t e s data f o r a standard sample and Table 5.9
Table 5.8
i l l u s t r a t e s data f o r an unknown
sample using t h e response f a c t o r s from Table 5.8 TABLE 5.8
I n t e r n a l n o r m a l i z a t i o n o f standard sample Component
Weight used(mg)
Weight
Peak area
Area
Area
%
%
wt.5
Response factor,F
1 2 3 4
354.3 296.7 542.3 441.5
21.67 18.15 33.17 27.01
3901 3654 5236 4768
22.22 20.81 29.82 27.15
180.0 201.3 157.8 176.5
1.000 1.118 0.877 0.981
Total
1634.8
100.00
17559
100.00
TABLE 5.9
C a l c u l a t i o n o f weiaht Dercent o f each comDonent i n unknown samDle Component
Peak area
Area
Area F
Weight
%
4265 3231 5496 3765
25.45 19.28 32.80 22.47
4265 2890 6267 3838
24.71 16.74 36.31 22.24
16757
100.00
11260
100.00
%
~~
1 2 3 4 Total
~~
( i v ) Standard a d d i t i o n . addition
are very
similar
I n t e r n a l s t a n d a r d i z a t i o n (see i above) and standard
techniques;
however,
the
r e q u i r e s no new component t o be added t o t h e sample. determined i s t h e standard which "spiking"
a sample.
t a t i v e technique. (1)
i s added.
standard In fact,
a d d i t i o n technique t h e component t o be
Standard a d d i t i o n
i s a l s o known as
Two i n j e c t i o n s o f t h e sample are necessary t o use t h e q u a n t i There are several v a r i a t i o n s o f t h e standard a d d i t i o n technique;
measurement o f t h e sample component o f
r e f e r e n c e s u b s t a n c e i n t h e sample, substance t o t h e sample.
interest,
( 2 ) measurement o f
and ( 3 ) measurement o f
For t h i s discussion we are o n l y concerned w i t h t h e system
where a sample component I s used as t h e standard substance, The f i r s t s t e p chromatographic unknown.
another
an added r e f e r e n c e
is to
inject
a known amount
i.e.,
(l.e.,
v a r i a t i o n 1. volume,
v)
of
The component o f i n t e r e s t , c, w i l l have a peak area A
t h e c o n c e n t r a t i o n o f component c,
i s expressed i n m o l a r i t y o r
C'
i n weight,
the If the
165 technique may be used.
The sample
N o w t h e component c w i I I have a peak area,
component t o be determined. means standard added). added.
i s then "spikedvf w i t h a known amount o f
Acs
T h i s increased peak area i s due t o t h e amount o f
the
(sub s "spiket1
Knowing t h e peak areas and t h e amount o f standard component c added, one i s
able t o c a l c u l a t e t h e amount o f c i n t h e o r i g i n a l sample. Assume 1.0 u l o f an unknown sample ( t o t a l volume = 1.0 m l ) produced a peak of 2 area equal t o 40.0 mn To t h e sample one add 10.0 p I o f t h e pure component having a
.
d e n s i t y o f 0.900 g/ml.
(0.900 g/ml) x 0.010 mi = 9 x
g = 9 mg
The o r i g i n a l volume o f sample was 1000 o f o r i g i n a l sample.
I f t h e volumes o f sample and added standard are a d d i t i v e ,
mg/1009 p I of 'Ispikel1.
2
150 mm
component c.
.
less t h e 1.0 u I i n j e c t e d g i v e 999
(1.0 m l ) ,
s o l u t i o n has a volume o f 1009
f i n a l "spiked"
peak of
p l
(5.32)
1.e..
pl,
9 x
g/1009
1.0 P I sample i n j e c t i o n o f t h e "spiked"
T h i s means t h e
increase o f
p1
the
or 9.00
s o l u t i o n produces a
110 mm2 i s due t o 8.92 x
mg o f
Thus,
t h e o r i g l n a l sample i n j e c t e d corresponded t o 3.24 x mg o f 2 m g ) / l l O mm ) . So t h e o r i g i n a l sample (1.0 ,I) Component c (40 rm2 x (8.92 x contained:
(3.24 x 10
3
mg/p1)(1000
p l )
= 3.24
(5.33)
mg component c
5.7 ANALYSIS O f AIR AND WATER CONTAMINANTS In t h i s section,
we p r e s e n t a number o f t h e more r e c e n t methods f o r t h e
a n a l y s i s o f b o t h a i r and w a t e r pollutants.
samples
The l i s t i n g i s by no means complete;
The methods a r e i n t w o c a t e g o r i e s : samples,
f o r many o f t h e commonly e n c o u n t e r e d however,
( 1 ) a i r samples,
it i s representative.
T a b l e 5.10
and ( 2 ) w a t e r
No d e t a i l e d e v a l u a t i o n s a r e presented f o r any o f t h e methods.
Table 5.11.
The main j u s t i f i c a t i o n o f such a s e c t i o n i s t o g i v e t h e reader a p o i n t o f o r i g i n a t which he may f i n d a discussion o f one or more o f h i s problems.
In addition,
we have
not given any references p r i o r t o 1978, unless they represent an e x i s t i n g p r e s e n t day state-of-the-art
methodology.
The r e a d e r d e s i r i n g more i n f o r m a t i o n a b o u t gas
chromatography methodology f o r a i r and water samples may c o n s u l t several v e r y good sources: Columbus,
( 1 ) Chemical A b s t r a c t s p u b l i s h e d by t h e American Chemical OH,
USA,
( 2 ) Gas and L i q u i d Chromatography
Abstracts
Society,
p u b l i s h e d by t h e
Chromatography Discussion Group o f Great B r i t a i n , Trent P o l y t e c h n i c , Nottingham,
( 3 ) The Preston Technical Company o f
Niles,
IL,
A p p l i c a t i o n Reviews of odd-numbered
USA.
A b s t r a c t s published by t h e Preston Technical Two o t h e r
Analytical
excellent
Chemistry ( r e f .
years and the Fundamental
Reviews o f
which a r e published i n t h e even-numbered years.
sources o f
and
Abstracts
information
are the
8 6 ) which a r e p u b l i s h e d i n t h e Analytical
Chemistry
(ref.
87)
Both a r e p u b l i s h e d by t h e American
166 Chemical Society,
Washington,
Dc,
USA.
The Fundamental Reviews cover t h e t o p i c of
gas chromatography whereas t h e A p p l i c a t i o n Reviews c o v e r a i r p o l l u t i o n , pollution,
water
and p e s t i c l d e residues.
TABLE 5.10 A I R SAMPLES Cmpound(s) tvoe
Column(s)
Tetra-,Hexa-, Hepta-,Octachlorodibenzop-dioxin isomers
2 m x 210 cm Low-resolution glass. 0.6% OV-17 MS +0.4$ P o l y S-179. 80-100 mesh Permabond methyl s i l i c o n e .
F l y Ash, Low p p t Activated Sludge, P a r t i culate Matter
N-nitrosamines
Basic A1203
Thermal energy anal y s i s
Cigarette smoke
0.1 ng
89
ECD, TID
Air
1-5 ng
90
F ID
Tobacco smoke
Organophosphorus SE-30 Pesticides Carbowax 20M Polycycl l c aromatic hydrocarbons and naphthalenes
--
Detector(s)
Sample twe
Detectlon I imit(s)
Reference 88
--
91
1,2-Dibromoethane
1.5% ov-17+ 1.95% ov-210
ECD
Ambient a i r
3 P9
92
1 ,2-Di bromo-3chloropropane
1 .5$ OV-l7+ 1.95% OV-210
6 3 ECD ~ ~
Ambient a i r
0.02 ppb
93
Nitrogen containing compounds
--
MS
C i g a r e t t e smoke
N i t r i c oxide
--
ECD
Air
0.01 ppm
95
Rel. Error
96
Waste gases from tetrachloroethane production. CI, HCI, CZH2, C02
6 nrn x 3 m TC D Silokhrom S-120 = ( l m ) + Porokhrom 3 (2m) coated w i t h di-buty lphthal ate
Waste gas
s-Triazine herbicides
Carbowax 20M WCOT
FID. AFlD
Environmental samp I es
Vinyl c h l o r i d e , ethyl chloride, Tetrachloroethy I ene
Carbowax 1500 on Carbopack A
F I D , Microwave plasma
Air
Pesticides
3% OV-17 on Chromosorb W-AW
ECD
Air
Hydrogen cyanide
Porapak Q
AFlD
A i r in f i r e environment
--
