Handbook of GC/MS: Fundamentals and Applications PDF
Preview Handbook of GC/MS: Fundamentals and Applications
Hans-Joachim Hubschmann Handbook of GUMS Hans-Joachim Hubschmann Handbook of G U M S Fundamentals and Applications ~BWILEY-VCH - Weinheim New York Chichester Brisbane Singapore .Toronto * * * Dr. Hans-Joachim Hiibschmann OmegaTech GmbH Mikroforum Ring 2 D-55234 Wendelsheim Germany This book was carefully produced. Nevertheless, author and publisher do not warrant the informa- tion contained therein to be free of errors. Readers are advised to keep in mind that statements, data, illustrations, procedural details or other items may inadvertently be inaccurate. Die Deutsche Bibliothek - CIP-Cataloguing-in-PublicationD ata A catalogue record for this publication is available from Die Deutsche Bibliothek ISBN 3-527-30170-4 0 WILEY-VCH Verlag GmbH, D-69469 Weinheim (Federal Republic of Germany), 2001 Printed on acid-free paper All rights reserved (including those of translation in other languages). No part of this book may be reproduced in any form - by photoprinting, microfilm, or any other means - nor transmitted or trans- lated into a machine language without written permission from the publishers. Registered names, trade- marks, etc. used in this book, even when not specifically marked as such. are not to be considered unpro- tected by law. Composition: ProSatz Unger, D-69469 Weinheim Printing: betz-druck GmbH, D-64291 Darmstadt Bookbinding: Wilh. Osswald & Co., D-67433 Neustadt/Weinstr Printed in the Federal Republic of Germany Foreword The coupling of gas chromatography with mass spectrometry is probably the oldest hybrid technique in instrumental analysis. The number of articles alone which were written on each individual technical aspect during the development of the method is enormous, not to mention articles on its applications. It is therefore to be expected that there would be a sufficient number of comprehensive and instructive books on the subject. However, this is not the case. Since the classical text of Bill McFadden (Techniques of Combined Gas Chromatogruphy/Muss Spectrometry written in 1973), which is, of course, completely out of date but should still be read for historical inter- est, there is nothing which really meets current demands. This deficit is all the more serious as GUMS has been regarded as a single method and has been developed as such for some time. Benchtop instruments, which have been available from many suppliers for several years, can be used in almost all routine operations and in mobile form even outdoors in the field far away from a laboratory. A large majority of analysts will probably work with such an instrument at some point. A comprehensive account of the methods is therefore not only very important, but also necessary. In addition the number of analyses prescribed by legislation, which must be carried out using GUMS, is constantly increasing. Now at last a scientist experienced in the field has taken up the challenge of filling the gap with the present book. It cannot be easy to find one’s way through the large quantity of technically relevant information, the complex theoretical aspects and the large number of important applications in widely varying areas of analytical chemis- try. The presentation needs to tread the difficult path between not being removed from the practice of the art, while not concentrating so intensively on everyday pro- blems that it carries within it the seed of its own decay. Another matter of concern here is that such a text might give rise to prejudice and perhaps also to incorrect prac- tices. Here also the greatest care is therefore necessary in the choice of words and ex- amples. However, with the present treatise the author has succeeded in overcoming these problems. He has prepared a book which is more than just a handbook. It has not only been written for the practical chemist who needs to consult it in the laboratory, but also for the analyst who wishes to familiarise himself with any or all the aspects of GUMS. The instrumental aspects of sample preparation, gas chromatographic separation and mass spectrometry are described carefully and comprehensively, including the most recent developments. A comparison with other common methods of detection is also included. The particular features of GUMS coupling are then discussed and fi- nally a large number of selected examples are given, showing how far this method has penetrated the field of analysis in environmental chemistry and medicine. VI Foreword After the chapter on sample preparation, in which the versatile possibilities of var- ious extraction methods are described, injection techniques are discussed. The author then deals with the important aspects of separation by gas chromatography and gives the relevant theoretical background and parameters for effecting and optimising it. The chromatography section ends with a short comparison of different GC detectors. The book then turns to mass spectrometry, explaining the most important terms with great clarity and concentrating on the most important aspects. After giving the strengths and weaknesses of the types of interface still in use today, the role of data systems in the production, determination and evaluation of data is given in appropriate detail. Finally the important classes of substance are listed and their analysis described with all the important practical aspects from separation to the choice of the correct in- ternal standard. Special emphasis is placed on quantitative determination, showing that the idea that GUMS coupling is difficult to use for precise quantitative measure- ments is no longer justifiable. The opposite is, in fact, the case. Comprehensive qual- ity assurance is more possible with GUMS because of the higher information content of the results, compared with classical detectors. Inaccuracies and errors are easier to find and to avoid than with nonspectrometric GC detectors. The final chapter contains examples of applications, a large number of which come from analysts in industry, research institutes and universities. Through its extensive and precise presentation of the most important parameters and results, this chapter gives the practical chemist some useful ideas which will make his everyday work more reliable and successful. Even if a particular application is no longer being used at some future time, the analyses presented here are so instructive that they will still be of value for a long period. Finally it should be mentioned that the references have been set out in such a way that both experienced personnel and beginners can find hrther details in the most important primary literature. This book, therefore, fills a long existing gap. It should enable the practical chemist to compare his procedure for the detection of a substance with others and perhaps to optimise it, to get stimulation or simply to recognise that the procedure which he is looking for has been well worked out in a similar form. The beginner will find preli- minary advice on working out his own procedures and clear information on problems and special cases, besides all the important basic concepts. The book can definitely be used to teach the use of GUMS, even though the scope, intention and price of this book do not directly suggest it as a textbook. It certainly contains much important ma- terial of the required quality. Prof. Michael Linscheid Humboldt University Berlin Preface to the English Edition More than three years have elapsed since the original German publication of the Handbook of GUMS. GUMS instrument performance has significantly improved in these recent years. GUMS methodology has found its sound place in many “classical” areas of application of which many application notes are reported as examples in this handbook. Today the use of mostly automated GUMS instrumentation is standard. Furthermore GUMS as a mature analytical technology with a broad range of robust instruments increasingly enters additional analytical areas and displaces the “classi- cal” instrumentation. The very positive reception of the original German print and the wide distribution of the handbook into different fields of application has shown that comprehensive in- formation about functional basics as well as the discussion about the practical use for different applications is important for many users for efficient method development and optimization. Without the support from interested users and the GUMS community concerned, the advancement and actualisation of this handbook would not be possible. My special thanks go to the active readers for their contribution to valuable discussions and de- tails. Many of the applications notes have been updated or replaced by the latest meth- odology. I would like to express my personal thanks to Dr. Brody Guggenberger (Thermo- Quest Corp., Austin TX), Joachim Gummersbach (ThermoQuest GmbH, Egelsbach), Gert-Peter Jahnke (ThermoQuest APG GmbH, Bremen), Prof. Dr. Ulrich Melchert (Robert-Koch-Institut, Berlin), Dr. Jens I? Weller (Institut fur Rechtsmedizin der Medizinischen Hochschule, Direktor Prof. Dr. med. H. D. Troger, Hannover), and Dr. John Ragsdale jr. (ThermoQuest Corp., Austin TX) for their valuable discussions and contributions with application documentation and data. My sincere thanks to Dr. Elisabeth Grayson for the careful text translation. I wish all users of this handbook an interesting and informative read. Comments and suggestions concerning further improvement of the handbook are very much ap- preciated. Sprockhovel, August 2000 Hans J. Hubschmann The great extension of the use of mass spectrometers has been accelerated consider- ably through their coupling with gas chromatography. From the middle of the 1980s integrated GUMS systems have been increasingly used in what were previously purely gas chromatography laboratories. At first the detector philosophy predomi- nated, as expressed in the trade names ‘mass specific detector’ or ‘ion trap detector’. Now, more than ten years later, highly developed powerful mass spectrometers have replaced mass spectrometric detectors. As far as GUMS coupling compatibilities are concerned, these benchtop machines are just as powerful as the early large instru- ments for organic analysis. Gas chromatography frequently provides the only inlet in GUMS benchtop instru- ments. The construction of the instruments, their operation and the software for data evaluation are specially orientated towards total integration (hyphenated technique). In this aspect GUMS systems differ significantly from large mass spectrometers (which can also be connected to a gas chromatograph). In the operation and in the evaluation software there are correspondences or direct connections with chromatography data systems. In this book GUMS is treated as a developed, stable and flexible coupling techni- que. The mutual dependence, effects and increase in power achieved by the coupling are clearly covered in the consideration of the basic functions and in the examples of applications. In the individual areas of gas chromatography and mass spectrometry ex- tensive and up to date books have been published. However, the analytical potential of the coupling of the two processes with consideration of the special instrumental tech- nique and its applications has, up till now, only been covered on the periphery. In this handbook both the basis of the GUMS coupling technique and the practical aspects of the evaluation of analyses are described. This is followed by detailed cover- age of current applications. The discussion of typical sample preparation procedures, which are coupled with GUMS either on- or off-line, takes into account the emerging trend of integrated sample preparation in GUMS systems. The basis, coupling techni- ques and parameters for selected instrumental methods, which are frequently used in direct association with GUMS analysis as well as classical procedures, are also given. The practical aspects of sample injection into capillary columns and the choice of columns for gas chromatography are described in detail. The possibilities for optimis- ing a particular separation are outlined. For GCiMS applications, as with classical de- tectors, the quality of the chromatography is the limiting factor for the whole system. In mass spectrometry emphasis is placed on practice of GUMS applications. The analytical background and the use of the ionisation techniques El and CI are dealt with in detail. The interested reader can consult the extensive current literature avail- able on the basics of the production of mass spectra and their interpretation. The X Preface to the German Edition widely used techniques for obtaining full scan mass spectra and the recording of indi- vidual masses (SIM) are supplemented by the GUMS techniques currently available even with benchtop instruments. The interpretation of GUMS chromatograms for qualitative and quantitative analy- sis has been given special consideration and explored in detail for everyday applica- tions. The comparison of mass spectra with those already published can initially be used for identification of substances. Modern computer techniques give rapid results and can also tempt the user into reaching rash positive or negative conclusions. A scheme for the interpretation and details of the decoding of mass spectra can form a starting point for further work in the explanation of unknown signals. For quantitative determinations, calibration procedures are given, in particular the use of labelled in- ternal standards. As a compendium for practical work there is also extensive coverage of applica- tions from different areas. For selected groups of substances methods of resolving pro- blems from recognised laboratories are presented. The aim of this section is to give in- formation and stimulus for practical situations and to promote the exchange of experi- ences between users. My grateful thanks extend to all those who have made writing this handbook possi- ble through their contributions, support and critical discussions: P. Bachhausen (Lan- desumweltamt NRW, Dusseldorf), H. Bittdorf (Kernforschungszentrum, Karlsruhe), P. Brand (Axel Semrau GmbH, Sprockhovel), Dr. U. Demme (Institut fir Rechtsmedi- zin, Klinikum der Friedrich-Schiller-Universitat, Jena), Th. Egert (Institut Fresenius, Taunusstein), H.-D. Eschke (Ruhrverband, Essen), Dr. P. Fiirst (Chemisches Landes- untersuchungsamt Nordrhein-Westfalen, Munster), W. Gatzemann (Dortmunder Stadt- werke AG, Schwerte), B. Grass (Institut fur Spektrochemie und angewandte Spektro- skopie, Dortmund), Dr. K. Grob (Kantonales Labor, Zurich, Switzerland), F. Heimlich (Institut fiir Spektrochemie und angewandte Spektroskopie, Dortmund), Dr. D. Henne- berg (Max-Planck-Institut fur Kohleforschung, Miilheim/Ruhr), H. Korpien (Stadt- werke Frankfurt am Main), Dr. J. Kurz (Institut Fresenius, Taunusstein), M. Landrock (Institut Fresenius Sachsen, Dresden), P. Lonz (Terrachem Essen GmbH, Essen), U. Matthiesen (Heinrich-Heine-Universitat, Dusseldorf), L. Matter (Dinslaken), H. Merten (Institut Fresenius Sachsen, Dresden), M. & M. Mierse (Berlin), A. Mulle (Axel Semrau GmbH, Sprockhovel), J. Niebel (Axel Semrau GmbH, Augsburg), Dr. J. Nolte (Institut fir Spektrochemie und angewandte Spektroskopie, Dortmund), Dr. W. Ockels (Spectralservice GmbH, Cologne), H.-G. Ostrop (AGR mbH, Gelsen- kirchen), Dr. Th. Paschke (Gesamtuniversitat Siegen), H. Richter (Institut Fresenius Sachsen, Dresden), Dr. H. Sachs (Institut fir Rechtsmedizin, Munich), Dr. C. Schlett (Gelsenwasser AG, Gelsenkirchen), Prof. Dr. H.-F. Scholer (Institut fir Sediment- forschung, Ruprecht-Karls-Universitat, Heidelberg), A. Semrau (Axel Semrau GmbH, Sprockhovel), Prof. Dr. H.-J. Stan (Institut fir Lebensmittelchemie, Technische Uni- versitat, Berlin), M. Tschickard (Landesamt fur Umweltschutz und Gewerbeaufsicht Rheinland-Pfalz, Mainz), Dr. H. Vorholz (Ingenieurgemeinschaft Technischer Um- weltschutz, Potsdam), Dr. M. Wislicenus (Staatliche Milchwirtschaftliche Lehr- und Forschungsanstalt, Kempten). I would like to thank the following companies for their generous provision of pro- duct documentation and application descriptions: Baker Chemikalien (Gross-Gerau), Bakers Hochvakuum GmbH (Wiesbaden-Nordenstedt/Asslar), Chrompack GmbH Preface to the German Edition XI (Frankfurt), Finnigan MAT GmbH (BremedSan Jose CA, USA), Fischer GmbH (Meckenheim), HNU/Nordion (Helsinki, Finland), ICT GmbH (Bad Homburg v. d. H.), ISCO Corporation (Lincoln NE, USA), Palisade Corporation (Newfield NY, USA), Perkin Elmer GmbH (Uberlingen), Pyrol AB (Lund, Sweden), Restek Corporation (Bellafonte PA, USA), Fa. Seekamp (Achim), SGE GmbH (Weiterstadt), Supelco Deutschland GmbH (Bad Homburg v. d. H.), Suprex Corporation (Pittsburgh, PA, USA), Tekmar Company (Cincinatti, OH, USA). I would also like to express my gratitude to the VCH editors Mrs Cornelia Reine- muth and Dr. Steffen Pauly for their generous support and Mrs Claudia Gross1 for her untiring assistance in the compilation of this book. For much stimulation and valuable help in drawing up the manuscript, I particularly thank my wife Gudrun. I am also grateful to our children for their limitless patience and the many coloured pictures they drew on my manuscripts! Sprockhovel, November 1996 Hans-Joachim Hubschmann Contents Foreword ......................................................... V Preface to the English Edition ........................................ VII Preface to the German Edition ........................................ IX 1 Introduction .............................................. 1 2 Basics ................................................... 7 2.1 Sample Preparation ......................................... 7 2.1.1 Sample Preparation by Solid Phase Extraction .................... 10 2.1.2 Sample Preparation by SFE ................................... 14 2.1.3 HeadspaceTechniques ....................................... 26 2.1.3.1 Static Headspace Technique .................................. 27 2.1.3.2 Dynamic Headspace Technique (Purge & Trap) ................... 35 2.1.3.3 Headspace versus Purge & Trap ............................... 45 2.1.4 Adsorptive Enrichment and Thermodesorption ................... 51 2.1.5 Pyrolysis ................................................. 59 2.2 Gas Chromatography ..................................... 67 2.2.1 GUMS Sample Inlet ............... 67 2.2.1.1 Hot Sample Injection ........................................ 68 2.2.1.2 Cold Injection Systems .......................... 72 2.2.1.3 Injection Volumes ........... ........................ 81 2.2.1.4 On-column Injection ........................................ 83 2.2.1.5 Cryofocusing .............................. ........... 86 2.2.2 Capillary Columns ................................... 88 2.2.2.1 Sample Capacity .................... ................... 89 2.2.2.2 Internal Diameter ..................... ............ 89 2.2.2.3 Film Thickness ........ ....................... .... 97 2.2.2.4 Column Length ............... ......................... 98 2.2.2.5 Adjusting the Carrier Gas Flow ..... ..................... 99 2.2.2.6 Properties of Stationary Phases ................................ 100 2.2.3 Chromatography Parameters .................................. 103 2.2.3.1 The Chromatogram and its Meanin .......................... 103 2.2.3.2 Capacity Factor k' ............. .......................... 106 2.2.3.3 Chromatographic Resolution ........... ................... 107 2.2.3.4 Factors Affecting the Resolution .............. ............. 110 2.2.3.5 Maximum Sample Capacity .................... ........ 112
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