Analytical Supercritical Fluid Extraction Techniques

Analytical Supercritical Fluid Extraction Techniques

Edited by

E.D. RAMSEY School of Applied Sciences University of Glamorgan

Pontypridd UK

~

" SPRINGER SCIENCE+BUSINESS, MEDIA, B.V.

Library of Congress Cataloging Card Number: 98-67006

ISBN 978-94-010-6076-9 ISBN 978-94-011-4948-8 (eBook) DOI 10.1007/978-94-011-4948-8

Printed on acid-free paper

Ali Rights Reserved © 1998 Springer Science+Business Media Dordrecht

Originally published by Kluwer Academic Publishers in 1998 Softcover reprint of the hardcover l st edition 1998

No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical,

inc1uding photocopying, recording or by any information storage and retrieval system, without written permission from the copyright owner.

Contents

Contributors

Preface

Abbreviations

x

xiii

xv

1 Introduction to supercritical fluid extraction in analytical science

A.A. CLIFFORD

1

1.1 Introduction I1.2 Pure and modified supercritical fluids 21.3 Density of a supercritical fluid 51.4 Viscosity and diffusion 81.5 Solubility in a supercritical fluid 91.6 Factors affecting supercritical fluid extraction 101.7 Modelling of supercritical fluid extraction 121.8 Continuous dynamic supercritical fluid extraction controlled by diffusion 131.9 Continuous dynamic supercritical fluid extraction controlled by both

diffusion and solvation 191.10 Continuous dynamic supercritical fluid extraction controlled by diffusion,

solvation and matrix effects 251.11 Extrapolation of continuous extraction results 301.12 Derivations and discussions of model equations 31

1.12.1 Extraction from a sphere controlled by transport only 321.12.2 Extraction from a film controlled by transport only 331.12.3 Extraction from a film, with non-uniform concentration distribution,

controlled by transport only 341.12.4 Extraction from a sphere controlled by transport and solvation 351.12.5 Extraction from a film controlled by transport and solvation 371.12.6 Extraction from a sphere controlled by transport, solvation and

matrix effects 381.12.7 Extraction from a sphere controlled by transport, solvation and matrix

effects, with non-uniform initial concentration 401.12.8 Extrapolation using the models 41

References 42

2 Supercritical fluid extraction instrumentation

D.C. MESSER, G.R. DAVIES, A.e. ROSSELLI,e.G. PRANGE AND l.W. ALGAIER

2.1 Introduction2.2 Analyte and matrix2.3 Modifier addition2.4 On-line and off-line supercritical fluid extraction

43

43434344

VI

3

CONTENTS

2.5 Supercritical fluid delivery2.5.1 Syringe pumps2.5.2 Reciprocating piston pumps2.5.3 Pneumatic amplifier pumps

2.6 Extraction vessels2.7 Supercritical fluid extraction flow-control devices and restrictors

2.7.1 Fixed-flow restrictors2.7.2 Variable-flow restrictors2.7.3 Summary

2.8 Supercritical fluid extraction collection modes2.8.1 Off-line liquid trapping2.8.2 Off-line solid phase collection2.8.3 Off-line solventless collection2.8.4 On-line collection modes2.8.5 Summary

2.9 Automation of supercritical fluid extraction2.9.1 Parallel supercritical fluid extraction systems2.9.2 Sequential supercritical fluid extraction systems2.9.3 Summary

2.10 Future developments2.10.1 Supercritical fluid extraction in the production environment2.10.2 Field portable systems2.10.3 Pressurized fluid extraction

References

Off-line supercritical fluid extraction for solid matrices

J.M. BAYONA

444547484851515457586060616162626264676768686868

72

3.1 Introduction 723.1.1 Sample preparation for supercritical fluid extraction 723.1.2 In situ supercritical fluid derivatization extraction schemes 753.1.3 In-line supercritical fluid extraction cleanup procedures 82

3.2 Experimental parameters of supercritical fluid extraction 853.2.1 Type of fluid 853.2.2 Effect of density 863.2.3 Selection of supercritical fluid extraction temperature 883.2.4 Selection of organic modifier 90

3.3 Extract collection 953.3.1 Extract trapping using solvents 953.3.2 Extract trapping using solid-phase sorbents 98

3.4 Mathematical models used for optimizing supercritical fluid extractionparameters 993.4.1 Supercritical fluid extraction kinetic models 993.4.2 Strategies for the optimization of supercritical fluid extraction

variables 100References 103

4 Supercritical fluid extraction strategies of liquid-based matrices

E.D. RAMSEY, B. MINTY AND R. HABECKI

109

4.1 Introduction 1094.2 General considerations 110

4.2.1 Vessels for direct liquid supercritical fluid extraction 1124.2.2 Vessels for indirect liquid supercritical fluid extraction 1164.2.3 Liquid supercritical fluid extraction vessel safety considerations 1184.2.4 Selection of support media for indirect liquid supercritical fluid

extraction 119

CONTENTS Vll

4.2.5 Restrictors and analyte traps for direct and indirect liquidsupercritical fluid extraction 123

4.3 Procedures involving pH control and use of additives to improvesupercritical fluid extraction efficiencies of analytes from aqueous samples 129

4.4 Aqueous sample derivatisation procedures 1334.5 Supercritical fluid extraction of metal ions from aqueous media 1354.6 Supercritical fluid extraction of analytes from enzymic reactions 1384.7 Inverse supercritical fluid extraction 1424.8 Selected liquid supercritical fluid extraction applications 1444.9 Conclusions 150References 153

5 Supercritical fluid extraction coupled on-line withgas chromatography

M.D. BURFORD

158

5.1 Introduction 1585.2 Techniques for coupling supercritical fluid extraction with gas

chromatography 1615.3 External trapping of analytes 1625.4 Internal accumulation of analytes 1655.5 Construction of supercritical fluid extraction-gas chromatography

instrumentation 1695.6 Optimisation of supercritical fluid extraction-gas chromatography 172

5.6.1 Extraction flow rate 1725.6.2 Column trapping temperature 1775.6.3 Column stationary phase thickness 181

5.7 Quantitative supercritical fluid extraction-gas chromatography 1845.8 Optimisation of extraction conditions for supercritical fluid extraction-gas

chromatography 1885.9 Supercritical fluid extraction-gas chromatography applications 195

5.9.1 Environmental samples 1955.9.2 Plant and plant-derived samples 201

5.10 Conclusions 204References 205

6 Coupled supercritical fluid extraction-capillary supercriticalfluid chromatography

H.J. VANDENBURG, K.D. BARTLE, N.J. COTTON ANDM.W. RAYNOR

208

6.1 Introduction 2086.2 Samples for which supercritical fluid extraction-capillary supercritical

fluid chromatography is applicable 2096.3 Influence of the sample matrix 2156.4 Instrumentation 2166.5 Extraction vessels 2166.6 Supercritical fluid extraction-capillary supercritical fluid chromatography

interface 2176.6.1 Aliquot sampling 2186.6.2 Trapping of analytes 221

6.7 Trapping procedures 2236.7.1 Trapping on uncoated fused-silica retention gaps 2236.7.2 Trapping on coated fused-silica retaining pre-columns 2256.7.3 Trapping on sorbent traps 225

Vlll CONTENTS

6.8 Use of modifiers and solvent venting 2276.9 Supercritical fluid extraction as a sample introduction technique 2296.10 Optimisation of conditions for supercritical fluid extraction-capillary

supercritical fluid chromatography 2306.11 Selected applications of supercritical fluid extraction-capillary supercritical

fluid chromatography 2306.12 Conclusions 235References 237

7 Supercritical fluid extraction coupled to packed columnsupercritical fluid chromatography

I.G.M. ANDERSON

239

7.1 Introduction 2397.2 Supercritical fluid chromatography: packed versus capillary columns 241

7.2.1 Efficiency 2437.2.2 Selectivity 2437.2.3 Sample capacity 2467.2.4 Detectors 2467.2.5 Analysis times 2487.2.6 Restrictors 2487.2.7 Temperature 248

7.3 Supercritical fluid extraction coupled to packed column supercritical fluidchromatography 2497.3.1 Supercritical fluid mobile phase 2507.3.2 Supercritical fluid extraction 2507.3.3 Supercritical fluid chromatography 2517.3.4 Supercritical fluid extraction coupled to packed column supercritical

fluid chromatography 2527.4 Instrumental aspects 257

7.4.1 Back pressure regulators 2577.4.2 Extraction vessels 2587.4.3 On-line analyte trapping and concentration 2667.4.4 On-line sample introduction 2677.4.5 Columns 2697.4.6 Detectors 2697.4.7 Fraction collection 270

7.5 Selected applications 2717.6 Future prospects 281Acknowledgement 282References 282

8 Supercritical fluid extraction for off-line and on-linehigh-performance liquid chromatographic analysis

AT REES

287

8.1 Introduction 2878.2 Supercritical fluid extraction-high-performance liquid chromatography 2888.3 Supercritical fluid extraction followed by off-line high-performance liquid

chromatography analysis 2898.4 On-line supercritical fluid extraction-high-performance liquid

chromatography sample preparation techniques 3308.5 Selected analyses performed using on-line supercritical fluid

extraction-high-performance liquid chromatography 3408.6 Conclusions 348References 349

9

CONTENTS

Supercritical fluid extraction coupled on-line with massspectrometry and spectroscopic techniques

B. MINTY, E.D. RAMSEY, A.T. REES, OJ. JAMES,P.M. O'BRIEN AND M.1. LITTLEWOOD

IX

353

9.1 Introduction 3539.2 On-line supercritical fluid extraction-Fourier transfonn infra-red

spectroscopy 3549.2.1 Flow cell supercritical fluid extraction-Fourier transfonn infra-red

spectroscopy 3569.2.2 Stop-flow supercritical fluid extraction-Fourier transfonn infra-red

spectroscopy 3619.2.3 On-line supercritical fluid extraction-supercritical fluid

chromatography-Fourier transfonn infra-red spectroscopy andsupercritical fluid extraction-capillary supercritical fluidchromatography-Fourier transfonn infra-red spectroscopy 362

9.3 On-line supercritical fluid extraction-nuclear magnetic resonancespectroscopy 368

9.4 On-line supercritical fluid extraction-gas chromatography-massspectrometry 369

9.5 On-line supercritical fluid extraction-capillary supercritical fluidchromatography-mass spectrometry 373

9.6 On-line supercritical fluid extraction-packed column supercritical fluidchromatography-mass spectrometry 379

9.7 On-line supercritical fluid extraction-liquid chromatography-massspectrometry 387

9.8 Conclusions 388References 389

10 Modern alternatives to supercritical fluid extraction

l.R. DEAN AND N. SAIM

10.1 Introduction10.2 Microwave-assisted extraction

10.2.1 Theory of microwave heating10.2.2 Instrumentation10.2.3 Selection of solvent and extraction conditions10.2.4 Applications of microwave-assisted extraction

10.3 Accelerated solvent extraction10.3.1 Theoretical considerations10.3.2 Instrumentation10.3.3 Applications: environmental matrices10.3.4 Applications: food matrices10.3.5 Applications: polymeric matrices

10.4 ConclusionsReferences

Appendix

Subject index

Matrix index

Analyte index

392

392393393394397397403403404405409413415416

418

423

426

428

Contributors

J.W. Aigaier

I.G.M. Anderson

R. Babecki

K.D. Bartle

J.M. Bayona

M.D. Burford

A.A. Clifford

N.J. Cotton

G.R. Davies

J.R. Dean

D.1. James

M.I. Littlewood

Isco Inc., PO Box 5347, 4700 Superior Street,Lincoln, NE 68504, USA

British American Tobacco, Regents Park Road,Millbrook, Southampton SO15 8TL, UK

School of Applied Sciences, University ofGlamorgan, Pontypridd, Mid GalmorganCF37 IDL, UK

School of Chemistry, University of Leeds,Leeds LS2 9JT, UK

Department of Environmental Chemistry,Centro de Investigacion y Desarrollo, Jordi Girona,18-26-E-08034 Barcelona, Spain

Unilever Research, Port Sunlight Laboratory,Quarry Road East, Bebington, Wirral L63 3JW, UK

School of Chemistry, University of Leeds,Leeds LS2 9JT, UK

Smith and Nephew, Group Research Center,York Science Park, Heslington, York YOI5DF, UK

Isco Inc., PO Box 5347,4700 Superior Street,Lincoln, NE 68504, USA

Department of Chemical and Life Sciences,University of Northumbria at Newcastle,Ellison Building, Newcastle upon Tyne NEI 8ST, UK

Nicolet Instruments Ltd, Budbrooke Road,Warwick CV34 5XH, UK

Nicolet Instruments Ltd, Budbrooke Road,Warwick CV34 5XH, UK

D.C. Messer

B. Minty

P.M. O'Brien

e.G. Prange

E.D. Ramsey

CONTRIBUTORS

Isco Inc., PO Box 5347, 4700 Superior Street,Lincoln, NE 68504, USA

School of Applied Sciences,University of Glamorgan, Pontypridd,Mid Galmorgan CF37 IDL, UK

Nicolet Instruments Ltd, Budbrooke Road,Warwick CV34 5XH, UK

Isco Inc., PO Box 5347, 4700 Superior Street,Lincoln, NE 68504, USA

School of Applied Sciences,University of Glamorgan, Pontypridd,Mid Galmorgan CF37 IDL, UK

xi

M.W. Raynor l

A.T. Rees

A.C. Rosselli

N. Saim

H.J. Vandenburg

Department of Chemistry and Applied Chemistry,University of Natal, Durban 4041, South Africa

Nycomed Amersham, Cardiff Laboratories,Forest Farm, Whitchurch, Cardiff CF4 8YD, UK

Isco Inc., PO Box 5347, 4700 Superior Street,Lincoln, NE 68504, USA

Department of Chemistry, Faculty of Physical andApplied Sciences, Universiti Kebangsaan, 43650UKM Bangi, Selangor, Malaysia

School of Chemistry, University of Leeds,Leeds LS2 9JT, UK

I Now at Matheson Gas Products, Advanced Technology Center, 1861 Lefthand Circle,Longmont, CO 80501, USA.

Preface

Since the late 1980s supercritical fluid extraction (SFE) has attractedconsiderable attention as a sample preparation procedure. The successfulimplementation of this technique can lead to improved sample throughput,more efficient recovery of analytes, cleaner extracts, economic replacementof halogenated solvents and a high level of automation compared withconventional sample preparation procedures. The present text was conceivedas an update of Supercritical Fluid Extraction and its Use in ChromatographicSample Preparation, edited by Dr. S.A. Westwood, which largely focused onthe on-line combination ofSFE with chromatographic techniques. However,in keeping with current trends, this book has also been expanded to providemore details of off-line SFE, with newer developments being described inseparate chapters. The topics described within this text are illustrated withmany 'state-of-the-art' applications, and each chapter provides a comprehen­sive list of references.The first chapter deals with the basic principles of SFE, discussing theproperties of supercritical fluids, factors affecting the kinetics of extractionand modelling of SFE. Chapter 2 is devoted to the essential aspects ofSFE instrumentation, describing the features and benefits of various instru­ment configurations, automation and future developments. Off-line SFE ofsolid matrices is covered in Chapter 3, which provides important details con­cerning sample preparation, in situ chemical derivatisation, extract cleanupprocedures, high-temperature SFE, extraction of metals and methods foroptimising SFE experimental parameters. Techniques involving SFE ofliquid matrices form the subject of Chapter 4 which deals with relevantinstrument considerations for such applications. Other topics covered inthis chapter include factors affecting the choice between direct and indirectliquid SFE procedures, in situ sample derivatisation, modifications toliquid samples to promote analyte extraction efficiencies, recovery of metalions from aqueous media, enzymes and inverse SFE. The next three chaptersare devoted to the on-line coupling of SFE with gas chromatography (GC),capillary and packed column supercritical fluid chromatography (SFC), withthe emphasis being placed on practical considerations for the selection of thebest techniques for different applications and sample matrices. The on-linecombination of SFE with high-performance liquid chromatography(HPLC) remains largely unexplored; reasons for this form the subject ofChapter 8, which also reviews off-line SFE as a sample preparation pro­cedure for HPLC. The applications cited within this chapter serve to dispel

xiv PREFACE

any notion that SFE is applicable only to analytes which are amenable to GCand SFC. The on-line combination ofSFE with spectroscopic techniques andmass spectrometry are covered in Chapter 9, which describes how theseprocedures offer great potential for the rapid confirmation or quantitationof target analytes along with the provision of structural information forunknown species. Insofar as all current sample preparation techniqueshave limitations which prevent their universal application, the final chapterdescribes the principles and applications of microwave-assisted and acceler­ated solvent extraction as emerging alternatives to SFE. For the convenienceof the reader, an appendix which contains pressure conversion scales andsupercritical fluid carbon dioxide density tables appear at the end of thebook.

E.D. RamseyPontypriddApril 1998

Abbreviations

AAAASACAESANOVAAPCIAPEASEAVRBECBHCBHT

BSTFABTEXCBsCCCICIDCPTHcSFCDADDBCPDBDTCDCMDODDOEDDTDDVPDEDTCDEHPDESDEXDHADHTDMACDIMPDIP

acetic anhydrideatomic absorption spectroscopyJr -acetylsulphamethazineatomic emission spectroscopyanalysis of varianceatmospheric pressure chemical ionisationalcohol phenol ethoxylateaccelerated solvent extractionautomated variable restrictorBond Elute Certifybenzene hexachloride2,6-ditertiarybutyl-4-methylphenol/butylatedhydroxytolueneN,O-bis(trimethylsilyl)trifluoracetamidebenzene, toluene, ethylbenzene, xylenechlorinated benzenescryogenic collectionchemical ionisationcollision-induced dissociation3-chloro-p-toluidine hydrochloridecapillary supercritical fluid chromatographyphotodiode-array detector1,2-dibromo-3-chloropropanedibutyldithiocarbamatedichloromethanedich!orodiphenyldichloroethanedichlorodiphenyldichloroethylenedichlorodiphenyltrichloroethanedichlorvosdiethyldithiocarbamatedi(2-ethylhexyl) phthalatediethylstibestrol and desaminosulphamethazinedexamethasonedocosahexanoic aciddihardenetallowdimethylammonium chloridediisopropyl methylphosphonatedirect insertion probe

XVI

DMHADTDMACECDEIELISAEPA

ESEESIFAMESFDDCFlDFOD%FOYFPDFTIRGCGPCGRGSRHAPA

HADHCBHCHHDCPHFAHPLCHPMCHTSFEi.d.IPALCLDPELLEMAEMBCMDPMEBOHMEKCMGAMIMOCMSD

ABBREVIAnONS

dimethylhexylamineditallowdimethylammonium chlorideelectron capture detectionelectron ionisationenzyme-linked immunosorbent assayeicosapentaenoic acid/CDS) Environmental ProtectionAgencyenhanced solvent extractionelectospray ionisationfatty acid methyl estersbis(trifluoroethyl)dithiocarbamateflame ionisation detection2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedionepercentage finish on yarnflame photomeric detectionFourier transform infra-red spectroscopygas chromatographygel permeation chromatographyN 4-glucuronylsulphamethazineGram-Schmidt reconstructed (chromatogram)halogenated aromatic phenoxy derivative of an aliphaticalkanehalogenated derivative of ureahexachlorobenzenehexachlorohexane/hexachlorocyclohexanehigh-density crystalline polymerhexafluoroacetylacetonehigh-pressure (or high-performance) liquid chromatographyhydroxypropyl methylcellulosehigh-temperature SFEinner diameterisopropyl alcoholliquid chromatographylow-density polyethyleneliquid-liquid extractionmicrowave-assisted extractioncarbendazimmedroxyprogesteronemebeverine alcoholmicellar electrokinetic chromatographymelengestrol acetatemethyl iodidemethoxychlormass selective detector

MTOAN4NISTNMRNNANPDOCPo.d.ODSOPPPACPAH

PBTPCBPCCDPDTCPEEKPETPFBBrPFEPTFEPTVPUFRPDRSDSDBSDMSFCSFDESFESFRSIMSMISMOPSMOZSMRSMZS04SPASPESQXSRMTACA

ABBREVIATIONS

methyltrioctylammonium chlorideN4-acetylsulphamethoxazoleNational Institute of Standards and Technologynuclear magnetic resonance spectroscopyneutron activation of analysisnitrogen phosphorus specific detectororganochlorine pesticideouter diameteroctadecylsilyl-modified silicaorganophosphate pesticidepolycyclic aromatic compoundpolycyclic aromatic hydrocarbon/polynuclear aromatichydrocarbonpoly(I,4-butylene terephthalate)polychlorinated biphenylpolychlorinated dibenzo-p-dioxinspyrollidinedithiocarbamatepoly(ether-ether-ketone)poly(ethylene terephthalate)pentaflourobenzylbromidepressurised fluid extractionpoly(tetrafluoroethene)programmed temperature vaporiserpolyurethane foamradiofrequency plasma detectorrelative standard deviationstyrene-divinyl benzenesulphadimethoxinesupercritical fluid chromatographysupercritical fluid derivatisation extractionsupercritical fluid extractionsupercritical fluid reactorsingle ion monitoringsulphamethizolesulphamethoxypyridazinesulphamethoxazolesulphamerazinesulphamethazineN4 -sulphatosulphamethazinesolid phase absorptionsolid phase extractionsulphaquinoxalinestandard reference materialtriamcinolone acetonide

XVll

XVlIl

TAMTBATBOHTBPTBPOTBZTCPTEATEPPTFATGATHATHABTHFTHPABTICTIDTLCTMAOHTMPATOPOTPHTPPOTTAZER2,4-D2,4,5-T

ABBREVIAnONS

trialkylaminetetrabutylammonium hydroxide/cationtrenbolonetributyl phosphatetri-n-butylphosphine oxidethiabendazole2,4,6-trichlorophenoltriethylamine and thermal energy analysistetraethylpyrophosphatetriflouroacetic acidthermal gravimetric analysistetrahexylammonium hydrogen sulphatetetrahexylammonium bromidetetrahydrofurantetraheptylammonium bromidetotal ion chromatogramthermionic detectionthin-layer chromatographytetramethylammonium hydroxidetrimethylphenylammonium hydroxidetri-n-octylphosphine oxidetotal petroleum hydrocarbontriphenylphosphine oxidethienoyltrifuoroacetylacetonezeranol2,4-dichlorophenoxyacetic acid2,4,5-trichlorophenoxyacetic acid