Chemical Derivatization in Analytical Chemistry Volume 2: Separation and Continuous Flow Techniques
MODERN ANALYTICAL CHEMISTRY Series Editor: David Hercules University of Pittsburgh ANALYTICAL ATOMIC SPECTROSCOPY By William G. Schrenk PHOTOELECTRON AND AUGER SPECTROSCOPY By Thomas A. Carlson MODERN FLUORESCENCE SPECTROSCOPY, VOLUME I Edited by E. L. Wehry MODERN FLUORESCENCE SPECTROSCOPY, VOLUME 2 Edited by E. L. Wehry MODERN FLUORESCENCE SPECTROSCOPY, VOLUME 3 Edited by E. L. Wehry MODERN FLUORESCENCE SPECTROSCOPY, VOLUME 4 Edited by E. L. Wehry APPLIED ATOMIC SPECTROSCOPY, VOLUME I Edited by E. L. Grove APPLIED ATOMIC SPECTROSCOPY, VOLUME 2 Edited by E. L. Grove TRANSFORM TECHNIQUES IN CHEMISTRY Edited by Peter R. Griffiths ION-SELECTIVE ELECTRODES IN ANALYTICAL CHEMISTRY, VOLUME I Edited by Henry Freiser ION-SELECTIVE ELECTRODES IN ANALYTICAL CHEMISTRY, VOLUME 2 Edited by Henry Freiser CHEMICAL DERIV A TIZATION IN ANALYTICAL CHEMISTRY, VOLUME 1 Chromatography Edited by R. W. Frei and 1. F. Lawrence CHEMICAL DERIVATIZATION IN ANALYTICAL CHEMISTRY, VOLUME 2 Separation and Continuous Flow Techniques Edited by R. W. Frei and 1. F. Lawrence
Chemical Derivatization in Analytical Chemistry Volume 2: Separation and Continuous Flow Techniques Edited by R. W. Frei Free University Amsterdam, The Netherlands and J. F. Lawrence Food Research Division oj the Department oj National Health and Welfare Ottawa, Ontario, Canada PLENUM PRESS NEW YORK AND LONDON
Main entry under title: Library of Congress Cataloging in Publication Data Chemical derivatization in analytical chemistry. (Modern analytical chemistry) Includes bibliographies and indexes. Contents: v. 1. Chromatography-v. 2. Separation and continuous flow techniques. 1. Gas chromatography. I. Frei, R. W. (Roland W) II. Lawrence, James F. III. Series. QD79.C45C48 ISBN-13: 978-1-4684-4204-5 DOl: 10.1007/978-1-4684-4202-1 543'.089 e-isbn-13: 978-1-4684-4202-1 81-5901 AACR2 1982 Plenum Press, New York Softcover reprint of the hardcover 1 st edition 1982 A Division of Plenum Publishing Corporation 233 Spring Street, New York, N.Y. 10013 All rights reserved No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher
Contributors William D. Bostick, Chemical Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee Larry D. Bowers, Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota H. B. S. Conacher, Food Research Division, Food Directorate, Health Protection Branch, Tunney's Pasture, Ottawa, Ontario Bo Karlberg, Bifok AB, Sollentuna, Sweden James F. Lawrence, Food Research Division, Food Directorate, Health Protection Branch, Tunney's Pasture, Ottawa, Ontario Wolfgang F. Lindner, Institute of Pharmaceutical Chemistry, University of Graz, Graz, Austria B. D. Page, Food Research Division, Food Directorate, Health Protection Branch, Tunney's Pasture, Ottawa, Ontario Goran Schill, Department of Analytical Pharmaceutical Chemistry, University of Uppsala, Biomedical Center, Uppsala, Sweden Douglas Westerlund, Astra Uikemedel AB, Research and Development Laboratories, S6derHilje, Sweden v
Preface With the second volume in this senes we have continued the theme of Volume 1 and expanded more generally into separation and continuousflow techniques. The first chapter gives an account on flow injection analysis. Thi~ technique has gained considerable interest in the recent past and offers many facets of the use of chemistry in automated analysis procedures. One of these facets is certainly also the use of ion-pairing reactions, and we have been fortunate to get two well-known experts to treat this subject. The use of ion-pairing techniques is being discussed from a batch extraction (sample handling) point of view as well as for flow injection and chromatographic purposes. Immobilized enzymes are another area of major attention and their multidirectional use in analytical chemistry is illuminated in Chapter 3 with special emphasis on their use in connection with liquid chromatography. Needless to say, similar techniques have also found their way into continuous-flow methodology (Auto-Analyzers) and many of the aspects discussed in Chapter 3 are adaptable to this end. The need and recent urgency for separation of optical isomers in many areas, particularly pharmaceutical and clinical analysis, has spurred a flurry of activity in this special section of chromatography. The current status of the field of optical isomer separation is competently reviewed in Chapter 4. Again this is a typical area wherein it is the proper use of chemistry that finally delivers a solution. The last two chapters deal with precolumn or prechromatographic derivatization techniques. More specifically, Chapter 5 comprehensively discusses the types of reactions available for different LC detection modes. Based on an up-tovii
viii Preface date listing of applications it permits the reader to find specific solutions to his problem. The last chapter deals with the analysis of food additives, by gas and liquid chromatography and makes an interesting comparison of techniques with and without the use of chemical derivatization. We believe that in Volume 2 we have been able to illuminate several areas of high actuality without sacrificing the general theme of chemical derivatization techniques. Specialists in many fields (food, agricultural, environmental, medicinal, pharmaceutical, and biochemical) of trace analysis in complex matrices wiii find solutions to their problems, and for the novice this volume will provide an easy and up-to-date access to the literature and know-how of the specific topics discussed. R. W. Frei J. F. Lawrence
Contents 1. Flow Injection Analysis Bo Karlberg 1. Introduction.............. 2. Basic Principles of FlA......... 3. Essential Components of an FIA System. 4. The Development and Performance of a Basic FIA System 4.1. The Development of PIA... 4.2. Performance of a Basic PIA System. 5. Controlled Dispersion.... 6. Stopped-Flow and Intermittent Pumping 7. Sample Gradient Methods 8. Two-Phase Methods-Extraction.... 9. Some Special Manifolds and Applications 10. Detection Principles 10.1. Photometry.... 10.2. Fluorimetry...... 10.3. Ion-Selective Electrodes 10.4. Redox Electrodes... 10.5. Electrochemical Detectors 10.6. Atomic Absorption Spectroscopy 10.7. Other Detection Principles References.... 3 6 10 10 12 13 19 22 24 27 29 29 30 30 31 32 32 37 38 2. Ion-Pairing Reactions in Analytical Chemistry G6ran Schill and Douglas Westerlund 1. Introduction.......... 2. Principles of Ion-Pair Extraction...... 2.1. Extraction Constants......... 2.2. Determination of Extraction Constants. 43 44 45 47 ix
x Contents 2.3. Association and Dissociation Processes.. 2.4. Protolysis in the Aqueous Phase 2.5. Complex Formation in the Organic Phase 2.6. Mechanism of Ion-Pair Extraction 3. Batch Extraction....... 3.1. Influence of Side Reactions 3.2. Back-Extraction... 3.3. Blank Compensations. 3.4. Applications.... 4. Continuous-Flow Systems. 4.1. Auto-Analyzer.... 4.2. Flow Injection Analysis (FIA). 5. Ion-Pair Chromotagraphy. 5.1. Liquid-Liquid Systems.... 5.2. Liquid-Solid Systems..... 5.3. Increase of Detection Sensitivity by uv-absorbing Counterion 5.4. Postcolumn Reactors References.............. 48 49 50 52 53 55 56 57 58 69 70 72 76 77 80 83 89 92 3. Immobilized Enzymes as Precolumn and Postcolumn Modification Reagents in Liquid Chromatography Larry D. Bowers and William D. Bostick 1. Introduction........... 2. Characteristics of Enzyme Catalysis 3. Immobilized Enzyme Technology 3.1. Approaches to Immobilization. 3.2. Effect of Immobilization on Enzyme Characteristics 4. Theoretical Aspects of Enzyme Reactors.. 4.1. Packed-Bed Reactors......... 4.2. Open Tubular Gas-Segmented Reactors 5. Applications......... 5.1. Precolumn Modifications. 5.2. Postcolumn Modifications. References...... 97 99 103 103 106 111 111 114 116 117 119 138 4. Resolution of Optical Isomers by Gas and Liquid Chromatography Structure Requirements of Sorbents and Solutes for Enantioselective Molecular Interactions Wolfgang F. Lindner 1. Why the Growing Interest in Separation Methods of Racemates? 2. Background on Optical Isomerism... 145 147
Contents xi 3. Principles of Enantioselective Chromatographic Separation Mechanisms 149 4. Resolution of Racemates by Gas-Chromatography 151 4.1. Direct Resolution via Chiral Stationary Phases... 154 4.2. Indirect Resolution of Racemates via Derivatization. 159 5. Direct LC Resolution Methods of Racemates..... 160 5.1. Chiral-Ligand Exchange Chromatography (CLEC) 160 5.2. Enantioselective lon-pair Chromatography.... 172 5.3. LC Resolution of Racemates via Multiple Hydrogen Bonding 173 5.4. Enantioselectivity via Charge Transfer Complexation 173 5.5. Resolution of Racemates via Chiral Cavities of Sorbents 175 6. Indirect Chromatographic Separation of Racemates 182 7. Conclusion 185 References....... 186 5. Prechromatographic Chemical Derivatization in Liquid Chromatography James F. Lawrence 1. Introduction. 2. Fluorescence Derivatization 2.1. Introduction..... 2.2. Measuring Techniques 2.3. Derivatization Reactions 3. uv-visible-absorbance Derivatization. 3.1. Introduction...... 3.2. Measuring Techniques 3.3. Derivatization Reactions 4. Derivatization for Other Detection Modes 4.1. Derivatization for Electrochemical Detection 4.2. LC-Atomic Absorption... 4.3. Radiochemical Derivatization References... 6. The Pros and Cons of Derivatization in the Chromatographic Determination of Food Additives B. D. Page and H. B. S. Conacher 1. Introduction 2. Emulsifiers and Stabilizers 2.1. Emulsifiers 2.2. Stabilizers 3. Artificial Sweeteners 3.1. Polyhydric Aleohols 3.2. Other Artificial Sweeteners 191 202 202 202 204 218 218 218 220 232 232 233 233 234 243 245 245 249 250 252 255
xii Contents 4. Antioxidants. 258 4.1. Gas Chromatography. 260 4.2. Liquid Chromatography 264 5. Preservatives. 268 5.1. Organic Acids and Esters. 268 5.2. Other Preservatives. 275 6. Synthetic Food Colors 277 7. Gums. 280 7.1. Gas Chromatography. 281 7.2. Liquid Chromatography 282 8. Waxes 282 References 284 INDEX 293