Sample preparation techniques in Analytical Chemistry
Sample Preparation Techniques in Analytical Chemistry
CHEMICAL ANALYSIS A SERIES OF MONOGRAPHS ON ANALYTICAL CHEMISTRY AND ITS APPLICATIONS Editor . D. WINEFORDNER Ⅴ OLUME162 A complete list of the titles in this series appears at the end of this volume
CHEMICAL ANALYSIS A SERIES OF MONOGRAPHS ON ANALYTICAL CHEMISTRY AND ITS APPLICATIONS Editor J. D. WINEFORDNER VOLUME 162 A complete list of the titles in this series appears at the end of this volume
Sample Preparation Techniques in analytical Chemistry Edited by SOMENATH MITRA Department of Chemistry and Environmental Science New Jersey Institute of Technology WILEY-INTERSCIENCE A JOHn WILEY SoNS, INC. PUBLICATION
Sample Preparation Techniques in Analytical Chemistry Edited by SOMENATH MITRA Department of Chemistry and Environmental Science New Jersey Institute of Technology A JOHN WILEY & SONS, INC., PUBLICATION
Copyright o 2003 by John Wiley Sons, Inc. All rights reserved. Published by John Wiley Sons, Inc, Hoboken, New Jersey Published simultaneously in Canada. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc, 222 Rosewood Drive, Danvers, MA 01923. 978-750-8400. fax 978-750-4470, or on the web at ww.copyright. com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley Sons, Inc, lll River Street, Hoboken, NJ 07030, (201)748-6011,fax(201)748-6008,e-mail:permreq@wiley.com Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created xtended by sales representatives or written sales materials. The advice and strategies tained herein may not be suitable for your situation. You should consult with a professional where appropriate. Neither the publisher nor author shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages. For general information on our other products and services please contact our Customer Care Department within the U.S. at 877-762-2974, outside the U.S. at 317-572-3993 or fax 317572-4002 wiley also publishes its books in a variety of electronic formats. Some content that appears in print, however, may not be available in electronic format. brary of Congress Cataloging-in-Publication Data: Sample preparation techniques in analytical chemistry/edited by Somenath Mitra Includes index ISBN 0-471-32845-6(cloth: acid-free paper) I Sampling. 2. Chemistry, Analytic--Methodology. I Mitra, S (Somenath), 1959- II. Series. QD754.S24S262003 543-dc21 2003001379 Printed in the United States of America 10987654321
Copyright 6 2003 by John Wiley & Sons, Inc. All rights reserved. Published by John Wiley & Sons, Inc., Hoboken, New Jersey. Published simultaneously in Canada. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400, fax 978-750-4470, or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748-6011, fax (201) 748-6008, e-mail: permreq@wiley.com. Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best e¤orts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional where appropriate. Neither the publisher nor author shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages. For general information on our other products and services please contact our Customer Care Department within the U.S. at 877-762-2974, outside the U.S. at 317-572-3993 or fax 317-572-4002. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print, however, may not be available in electronic format. Library of Congress Cataloging-in-Publication Data: Sample preparation techniques in analytical chemistry / edited by Somenath Mitra. p. cm.— (Chemical analysis ; v. 162) Includes index. ISBN 0-471-32845-6 (cloth : acid-free paper) 1. Sampling. 2. Chemistry, Analytic—Methodology. I. Mitra, S. (Somenath), 1959– II. Series. QD75.4.S24S26 2003 543—dc21 2003001379 Printed in the United States of America 10 9 8 7 6 5 4 3 2 1
To the hands in the laboratory the heads seeking information
To the hands in the laboratory and the heads seeking information
CONTENTS CONTRIBUTORS vIl PREFACE CHAPTER 1 SAMIPLE PREPARATION: AN ANALYTICAL PERSPECTIVE 11. The measurement process I.1. 1. Qualitative and Quantitative Analysis 1. 1.2. Methods of Quantitation 1. 2. Errors in Quantitative Analysis: Accur 1. 2.1. Accuracy 1. 2.2. Precision 1. 2.3. Statistical Aspects of Sample 13. Method Performance and metho Validation 1.3.1. Sensitivity 1.3.2. Detection Limit 14 1.3.3. Range of Quantitation 1.3. 4. Other Important Parameters 13.5. Method validation 1.4. Preservation of Samples 1. 41. volatilization 19 1. 4.2. Choice of Proper Containers 1.4.3. Absorption of Gases from the 1. 4. 4. Chemical Changes 145. Preservation of unstable solids
CONTENTS CONTRIBUTORS xvii PREFACE xix CHAPTER 1 SAMPLE PREPARATION: AN ANALYTICAL PERSPECTIVE 1 Somenath Mitra and Roman Brukh 1.1. The Measurement Process 1 1.1.1. Qualitative and Quantitative Analysis 3 1.1.2. Methods of Quantitation 4 1.2. Errors in Quantitative Analysis: Accuracy and Precision 6 1.2.1. Accuracy 6 1.2.2. Precision 6 1.2.3. Statistical Aspects of Sample Preparation 10 1.3. Method Performance and Method Validation 12 1.3.1. Sensitivity 13 1.3.2. Detection Limit 14 1.3.3. Range of Quantitation 15 1.3.4. Other Important Parameters 15 1.3.5. Method Validation 16 1.4. Preservation of Samples 17 1.4.1. Volatilization 19 1.4.2. Choice of Proper Containers 19 1.4.3. Absorption of Gases from the Atmosphere 20 1.4.4. Chemical Changes 20 1.4.5. Preservation of Unstable Solids 20 vii
vIll CONTENTS 1.5. Postextraction procedures 21 1.5.1. Concentration of Sample Extracts 1.6. Quality Assurance and Quality Control during Sample Preparation 1. 1. Determination of Accuracy and Precision 16.2. Statistical Control 1.6.3. Matrix Control 164. Contamination control SECTION A EXTRACTION AND ENRICHMENT IN SAMPLE PREPARATION CHAPTER 2 PRINCIPLES OF EXTRACTION AND THE EXTRACTION OF SEMIVOLATILE ORGANICS FROM LIQUIDS Martha J. m. wells 2.1. Principles of Extraction 2.1.1. Volatilization 2. 1.3. Acid-Base Equilibria 2. 1.4. Distribution of Hydrophobic Ionogenic Organic Compounds 2.2. Liquid-Liquid Extraction 2. 2.1. Recovery 770 2.2. 2. Methodology 2.2.3. Procedures 2.2.4. Recent Advances in Techniques 2.3. Liquid-Solid Extraction 2.3.1. Sorption 2 4. Solid-Phase Extraction 2,41. Sorbents in spe 2.4.2. Sorbent selection 2.4.3. Recovery 4588%9 2.4. 4. Methodology
1.5. Postextraction Procedures 21 1.5.1. Concentration of Sample Extracts 21 1.5.2. Sample Cleanup 22 1.6. Quality Assurance and Quality Control during Sample Preparation 25 1.6.1. Determination of Accuracy and Precision 28 1.6.2. Statistical Control 29 1.6.3. Matrix Control 31 1.6.4. Contamination Control 32 References 35 SECTION A EXTRACTION AND ENRICHMENT IN SAMPLE PREPARATION CHAPTER 2 PRINCIPLES OF EXTRACTION AND THE EXTRACTION OF SEMIVOLATILE ORGANICS FROM LIQUIDS 37 Martha J. M. Wells 2.1. Principles of Extraction 37 2.1.1. Volatilization 38 2.1.2. Hydrophobicity 43 2.1.3. Acid–Base Equilibria 50 2.1.4. Distribution of Hydrophobic Ionogenic Organic Compounds 57 2.2. Liquid–Liquid Extraction 57 2.2.1. Recovery 60 2.2.2. Methodology 66 2.2.3. Procedures 68 2.2.4. Recent Advances in Techniques 72 2.3. Liquid–Solid Extraction 74 2.3.1. Sorption 75 2.4. Solid-Phase Extraction 78 2.4.1. Sorbents in SPE 81 2.4.2. Sorbent Selection 96 2.4.3. Recovery 99 2.4.4. Methodology 108 viii contents
CONTENTS 2. 4.5. Procedures 111 2. 4.6. Recent Advances in SPe l13 2.5. Solid-Phase Microextraction 2.5.1. Sorbents 2.5.2. Sorbent selection l18 2.5.3. Methodology l19 2.5.4. Recent Advances in Techniques 124 2.6. Stir Bar Sorptive Extraction 125 2.6.2. Methodology 2.6.3. Recent Advances in Techniques l29 2.7. Method Comparison 130 References CHAPTER 3 EXTRACTION OF SEMIVOLATILE ORGANIC COMPOUNDS FROM SOLID MATRICES Dawven Kou and Somenath Mitr 3.1. Introduction 3.1.1. Extraction Mechanism 3.1.2. Preextraction Proced 3.1.3 Postextraction procedures 14 3.2. Soxhlet and Automated Soxhlet 3. 2.1. Soxhlet Extraction 142 3. 2.2. Automated Soxhlet Extraction 3.2.3. Comparison between Soxtec and 145 33. Ultrasonic extraction Selected A Comparison with Soxhlet 3.4. Supercritical Fluid Extraction 3.4.1. Theoretical Considerations 3.4.2. Instrumentation l52 3.4.3. Operational Procedures 153 3.4.4. Advantages/Disadvantages and Applications of SFE 3.5. Accelerated Solvent extraction
2.4.5. Procedures 111 2.4.6. Recent Advances in SPE 113 2.5. Solid-Phase Microextraction 113 2.5.1. Sorbents 116 2.5.2. Sorbent Selection 118 2.5.3. Methodology 119 2.5.4. Recent Advances in Techniques 124 2.6. Stir Bar Sorptive Extraction 125 2.6.1. Sorbent and Analyte Recovery 125 2.6.2. Methodology 127 2.6.3. Recent Advances in Techniques 129 2.7. Method Comparison 130 References 131 CHAPTER 3 EXTRACTION OF SEMIVOLATILE ORGANIC COMPOUNDS FROM SOLID MATRICES 139 Dawen Kou and Somenath Mitra 3.1. Introduction 139 3.1.1. Extraction Mechanism 140 3.1.2. Preextraction Procedures 141 3.1.3. Postextraction Procedures 141 3.2. Soxhlet and Automated Soxhlet 142 3.2.1. Soxhlet Extraction 142 3.2.2. Automated Soxhlet Extraction 143 3.2.3. Comparison between Soxtec and Soxhlet 145 3.3. Ultrasonic Extraction 145 3.3.1. Selected Applications and Comparison with Soxhlet 147 3.4. Supercritical Fluid Extraction 148 3.4.1. Theoretical Considerations 148 3.4.2. Instrumentation 152 3.4.3. Operational Procedures 153 3.4.4. Advantages/Disadvantages and Applications of SFE 154 3.5. Accelerated Solvent Extraction 155 contents ix
CONTENTS 3.5.1. Theoretical Considerations 3.5.2. Instrumentation 3.5.3. Operational procedures 3.5. 4. Process Parameters 3.5.5. Advantages and Applications of 6. Microwave-Assisted extraction 3.6. 1. Theoretical Considerations 3. 6.2. Instrumentation 3.6.3. Procedures and Advantages/ Disadvantag 3. 6. 4. Process Parameters 3.6.5. Applications of MAE 7. Comparison of the Various Extraction Techniques CHAPTER 4 EXTRACTION OF VOLATILE ORGANIC COMPOUNDS FROM SOLIDS AND LIQUIDS Gregory C Slack, Nicholas H. Snow, and Dawen Kou 4.1. Volatile Organics and Their Analysis 4. 2. Static Headspace Extraction 4.2.1. Sample Preparation for Static Headspace Extraction 4.2.2. Optimizing Static Headspace Extraction Efficiency and Quantitation 4.2.3. Quantitative Techniques in Static Headspace Extraction 4.3. Dynamic Headspace Extraction or Purge and Trap 431. Instrumentation 4.3.2. Operational Procedures in Purge and Trap 4.3.3. Interfacing Purge and Trap with GC 44. Solid-Phase Microextraction
3.5.1. Theoretical Considerations 155 3.5.2. Instrumentation 156 3.5.3. Operational Procedures 158 3.5.4. Process Parameters 159 3.5.5. Advantages and Applications of ASE 161 3.6. Microwave-Assisted Extraction 163 3.6.1. Theoretical Considerations 163 3.6.2. Instrumentation 164 3.6.3. Procedures and Advantages/ Disadvantages 170 3.6.4. Process Parameters 170 3.6.5. Applications of MAE 173 3.7. Comparison of the Various Extraction Techniques 173 References 178 CHAPTER 4 EXTRACTION OF VOLATILE ORGANIC COMPOUNDS FROM SOLIDS AND LIQUIDS 183 Gregory C. Slack, Nicholas H. Snow, and Dawen Kou 4.1. Volatile Organics and Their Analysis 183 4.2. Static Headspace Extraction 184 4.2.1. Sample Preparation for Static Headspace Extraction 186 4.2.2. Optimizing Static Headspace Extraction E‰ciency and Quantitation 187 4.2.3. Quantitative Techniques in Static Headspace Extraction 190 4.3. Dynamic Headspace Extraction or Purge and Trap 194 4.3.1. Instrumentation 194 4.3.2. Operational Procedures in Purge and Trap 199 4.3.3. Interfacing Purge and Trap with GC 199 4.4. Solid-Phase Microextraction 200 x contents
CONTENTS 4. 4.1. SPME Method Development for 4. 4.2. Choosing an SPME Fiber Coating 4.4.3. Optimizing Extraction Conditions 4. 4.4. Optimizing SPME-GC Injection 4.5. Liquid-Liquid Extraction with Large- Volume Injection 208 4.5.1. Large-Volume GC Injectic 08 4.5.2. Liquid-Liquid Extraction for Large-Volume Injection 46. Membrane extraction 212 4.6.1 Membranes and membrane 4.6.2 Membrane introduction mass Spectrometry 4.6.3. Membrane extraction with gas Chromatography 218 4.6.4. Optimization of Membrane Extraction 47. Conclusions 223 References CHAPTER 5 PREPARATION OF SAMPLES FOR METALS ANALYSIS 227 5.1. Introduction 5.2. Wet Digestion Methods Wet ash 5.2.2. Microwave Digestion 5.2.3. Comparison of Digestion Methods 235 5.2.4. Pressure Ashing 5.2.5. Wet Ashing for Soil S 5.3. Dry Ashing 5.3. 1. Organic Extraction of Metals 5.3.2. Extraction with Supercritical Fluids 244 5.3.3. Ultrasonic Sample Preparation 245
4.4.1. SPME Method Development for Volatile Organics 201 4.4.2. Choosing an SPME Fiber Coating 204 4.4.3. Optimizing Extraction Conditions 206 4.4.4. Optimizing SPME–GC Injection 207 4.5. Liquid–Liquid Extraction with LargeVolume Injection 208 4.5.1. Large-Volume GC Injection Techniques 208 4.5.2. Liquid–Liquid Extraction for Large-Volume Injection 211 4.6. Membrane Extraction 212 4.6.1. Membranes and Membrane Modules 215 4.6.2. Membrane Introduction Mass Spectrometry 217 4.6.3. Membrane Extraction with Gas Chromatography 218 4.6.4. Optimization of Membrane Extraction 222 4.7. Conclusions 223 References 223 CHAPTER 5 PREPARATION OF SAMPLES FOR METALS ANALYSIS 227 Barbara B. Kebbekus 5.1. Introduction 227 5.2. Wet Digestion Methods 230 5.2.1. Acid Digestion—Wet Ashing 231 5.2.2. Microwave Digestion 234 5.2.3. Comparison of Digestion Methods 235 5.2.4. Pressure Ashing 237 5.2.5. Wet Ashing for Soil Samples 237 5.3. Dry Ashing 240 5.3.1. Organic Extraction of Metals 241 5.3.2. Extraction with Supercritical Fluids 244 5.3.3. Ultrasonic Sample Preparation 245 contents xi