ISSN:0003-2654    

DOI:10.1039/AN99318BP021

出版商:RSC    

年代:1993

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN99318FX025

出版商:RSC    

年代:1993

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN99318BX027

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

ANALYST, JULY 1993, VOL. 118 81N Book Reviews Analytical Methods for Pesticides and Plant Growth Regulators. Volume XVI. Specific Applications Edited by Joseph Sherma. Pp. ix + 268. Academic Press. 1988. Price US$65.00. ISBN 0-1 2-78431 6-7. This volume of the series begun in 1963 by Zweig continues the valuable reference work for chemists involved with the analysis of pesticides and plant growth regulators. As men- tioned in the preface, this book is the first to be published since the death of Gunter Zweig but the layout follows the familiar style of previous volumes in this series dealing with specific applications. Although the book is divided into three parts (insecticides and insect growth regulators, herbicides, class analysis), it divides naturally into two sections, one dealing with specific insecticides and herbicides and the other with three different compound classes.Part I contains three chapters covering the compounds ethoprop, fenoxycarb and fenvalerate. As usual in this series, the chapters on ethoprop and fenoxycarb have been written by analysts working for the companies producing the pesticides commercially and each chapter follows the standard format with the first part devoted to general information on the nomenclature, history and properties of the compound concerned, and the second part describing methodology for the product and residue analysis of the pesticides. The section on fenvalerate is merely an update to the information on this compound contained in Volume XI11 of the series, and only gives details on the analysis of fenvalerate emulsifiable concentrate formulation.Part I1 includes Chapters 4-8 and covers the herbicides chlorimuron ethyl, chlorsulfuron, glyphosate, metsulfuron methyl and sulfometuron methyl. Four of the chapters deal with compounds of the same chemical class and are written by analysts working for the same company. The sections on residue analysis of glyphosate and metsulfuron methyl are interesting in that the former describes the use of HPLC with post-column fluorogenic labelling for quantification, and the latter the use of multidimensional HPLC for metabolite analysis. Chapter 9 deals with the determination of anticoagulant rodenticides and is written by Hunter, an internationally recognized authority on this subject. The majority of the chapter is devoted to background information and formula- tion and residue analytical methodology for the rodenticides chlorophacinone, diphacinone, brodifacoum, bromadiolone, coumatetralyl, difenacoum and warfarin.Multiresidue meth- ods, which are particularly useful in cases of suspected poisoning, are also described and the chapter concludes with a brief review of immunoanalytical procedures for the determi- nation of rodenticide residues. The penultimate chapter describes advances in pyrethroid determination, updating the analytical methodology for these compounds reported in Volume XI11 of the series. Fairly comprehensive references are given to the analysis of many different pyrethroids by gas and liquid chromatography, and the author has effectively summarized the published meth- odology in a series of tables.Because many of the newer pyrethroid products are often based on the most active isomer(s) of compounds exhibiting both optical and geometric isomerism, it is appropriate that the chapter closes with a review of the published literature on the analysis of pyrethroid enantiomers. The determination of fumigant residues in stored foodstuffs is the theme for the final chapter of this book. Detailed multiresidue procedures based on cold extraction, steam distillation and purge-and-trap extraction are followed by specific sections on a wide range of fumigants. In summary, this book supplements this comprehensive reference series dealing with the analysis of specific pesticides and plant growth regulators and is a useful reference work for those laboratories involved in the analysis of the compounds mentioned above. S.Forbes Analytical Methods for Pesticides and Plant Growth Regulators. Volume XVII. Advanced Analytical Tech- niques Edited by Joseph Sherma. Pp. ix + 272. Academic Press. 1989. Price US$65.00. ISBN 0-1 2-784317-5. This book, which continues the series on product and residue analytical methodology for pesticides and plant growth regulators, deals with a variety of analytical techniques ranging from sweep co-distillation to immunoassay. Conse- quently it can be treated either as a reference work for pesticide analysts planning to take a new technology onstream in their laboratory, or can be read from cover to cover by those wishing to keep abreast of the newer developments in this field. All chapters contain fairly comprehensive lists of references for those wishing to obtain more information on a particular technique.The first chapter deals with sampling techniques for pesticide analysis. Given the importance of correct sampling procedures in analytical work, it is good to see this frequently overlooked subject included in the present volume. Following a short section on sampling theory, the majority of the chapter is devoted to sections describing the sampling of air, food and crops, soil and water. Chapter 2 focuses on universal extraction and clean-up methods for pesticide residue analysis. The author gives a fairly lengthy description of solvent systems for pesticide extraction and the evolution of universal extraction methods; he then proceeds to describe the use of GPC as a universal clean-up procedure.Clean-up of extracts by sweep co-distilla- tion is covered in the third chapter of this book. Commercial and home-built equipment for performing sweep co-distilla- tion are described and then several applications of the technique are given, including the isolation of a variety of pesticide residues from several sample matrices including animal fats and plant material. Useful recovery data are included as are GC traces of extracts following clean-up by sweep co-distillation. Although the majority of this volume is of greatest value to the pesticide residue analyst, Chapters 4-6 (which deal respectively with GC-FTTR, LC-MS, and computer evalua- tion of GC data) are of more general analytical interest.The value of GC-FTIR for pesticide isomer discrimination is demonstrated in Chapter 4 by reference to the analysis of organochlorine insecticides. Chapter 5 starts with a fairly comprehensive description of LC-MS interfaces and proceeds with a review of the application of LC-MS to pesticide analysis in which the author makes reference to a variety of compound types including carbamates, phenoxyacids, organophos- phates, triazines, ureas and organochlorines. The first part of Chapter 6, which describes the instrumentation and operation of chromatographic data systems, does not particularly warrant inclusion in this book and dilutes the more informa- tive section on author-written computer programs for the GC screening of pesticide residues.82N ANALYST, JULY 1993, VOL.118 The final chapter of this volume describes immunoassay techniques for pesticide analysis; such techniques have gained much attention in recent years and this has culminated in commercially available test kits for pesticide residue analysis. Hammock et al. first introduce the reader to the principles and variants of immunoanalytical techniques before describing the systems that have been developkd for the analysis of specific pesticides. In addition to describing the technical aspects of this technology, the authors address other important issues such as the acceptance and validation of immunoanalytical techniques. In summary, this is a book that, owing to the diversity of subject matter covered, holds the reader’s attention.Although of greatest value to those dealing with pesticide residue analysis, a large part of the book is also of interest to those involved in more general aspects of analytical chemistry. S. Forbes Chemical Instrumentation: A Systematic Approach. Third Edition By Howard A. Strobel and William R. Heineman. Pp. xxiii + 1210. Wiley. 1989. Pricef34.85. ISBN 0-471-61223-5. This book is a major update of the second edition published some 15 years earlier. It is claimed that a primary goal in the update has been to reflect the extensive developments in instrumental analytical chemistry. This claim is largely ful- filled with a comprehensive range of measurement techniques. Fundamental principles are developed and their realization in instrumental form described in a logical way.Although somewhat austere in its presentation, the book is packed with information that will benefit the teaching of the subject at both undergraduate and postgraduate levels. Good use is made of worked examples, with exercise questions added to all but two of the 32 chapters, spanning 1200 pages. Useful and pertinent references are included as a bibliography to each chapter. ‘The strength of this book lies in its emphasis on the instrumentation behind the chemical measurements’. As with any all-encompassing texts of this kind, it has both its strengths and its weaknesses. The strength of this book lies in its emphasis on the instrumentation behind the chemical measurements. The sections on optical spectroscopic, chro- matographic and electroanalytical techniques are particularly good in this respect, with a useful section devoted to energetic particle and X-ray methods.These sections are underpinned by 12 chapters devoted to basic electronics, optics and quantification. The basic quantification section includes a useful overview of statistics, measurement quality, calibra- tion , chemometrics and signal-to-noise enhancement. The section on basic electronics is disappointing and outdated and perhaps attempts the impossible in a field that is changing so rapidly. For example, under power supplies no discussion of modern switched-mode devices is given. However, what is lacking in basic electronics is more than compensated for in the excellent section on basic optics, which includes com- prehensive discussion of spectrometer design.If it has a weakness it is the rather sparse use of chemical measurement applications and examples as well as a small number of curious editorial anomalies: for example, why is more space devoted to the discussion of the obsolete liquid chromatographic syringe pump than to its ubiquitous reciprocating counter- part? But, overall, this is a book worthy of serious considera- tion against a handful of the other established ‘giants’ in the competitive field of instrumental analytical chemistry texts. With its emphasis on the facet of instrumentation, it has no equal. P. R. Fielden Algorithms for Chemists By Jure Zupan. Pp. xv + 290. Wiley. 1989. Price f39.50. ISBN 0-471-92173-4. The title Algorithms for Chemists is perhaps an understate- ment of the contents of the book.The book is based on a course taught by Jure Zupan to students at the University of Ljubljana. The contents are, therefore, a comprehensive introduction to understanding and using computers in a chemistry environment. Although writing and developing algorithms are featured, data collection, processing of data and data handling are the real subject material. The book opens with chapers outlining the form and nature of data as represented by measured and multidimensional data using mass spectra and NMR data as examples. Groups of data (files) are then considered and the various structures, formats and types explained with reference to a selection of operating systems such as MS DOS as used on PCs and DEC’s VMS and FORTRAN, BASIC and PASCAL programming languages.Example algorithms include techniques for linking partitioned records, hash algorithms, techniques for genera- tion of random numbers and sorting. Having covered the nature of data and files the scene moves to processing data, using infrared spectra as examples. Techniques discussed include smoothing data, derivatives, peak detection, integra- tion and baseline correction. Optimization and transform techniques frequently feature in modern instruments. It is pleasing to see a readable explanation of methods such as Fourier and Hadamard transformations, principal component analysis, autocorrelation, and deconvolution, whilst optimiza- tion techniques are illustrated by simplex methods. Data handling looks at clustering and pattern recognition methods including the fundamental concepts and the role they play in data handling.Handling of chemical structures explains various representation notations for coding structural fragments, connectivity matrix and connection tables are developed and given for a number of small linear and cyclic molecules. Fractal images have achieved extensive publicity in the popular scientific press but fractal techniques do have serious applications typified by Brownian motion of small molecules, population patterns of micro-organisms and the chaotic flow of gases and liquids. Jure Zupan includes a chapter on fractal processes, which serves as an overview to the subject. The final chapter is in a similar vein with an explanation of expert systems and the key functional com- ponents to a working database system.The theme is developed using a spectroscopic expert system as an example. Although algorithms are scattered throughout the various chapters the book is really an introduction to scientific data handling, processing and filing, with many examples of applications; a sound readable book that can be recommended as a good introductory text on computer techniques for processing and handling data. A . Braith waite Computerised Multiple Input Chromatography By M. Kalijurand and E. Kullik. Ellis Horwood Series in Analytical Chemistry. Pp. 225. Ellis Horwood. 1989. Price f45.00. ISBN 0-7458-01 20-X (Ellis Horwood); 0-470- 21 228-4 (Halstead Press). This book is one of over sixty books covering specialized aspects of analytical chemistry and chemical measurements. Thus the book under review is a thorough treatment of a rather novel approach to chromatographic separations, namely that of using computer control of the sample introduction cycle, with particular emphasis on gas chromato-ANALYST, JULY 1993, VOL.118 83N graphic techniques. A thorough explanation of the mathema- tical principles of the technique and algorithms to process the data output is included and is not for the faint hearted. However, the book is written in a clear, lucid manner and can be used as an introduction to the technique by the curious chromatographer or those with considerable knowledge of computer techniques. Computers can contribute to three aspects of a chromato- graphic analytical procedure: control of the instrument functions, processing the signal output to obtain the chroma- tographic data and finally to derive further information from the data using chemometrics.The book introduces chromato- graphic instrumentation and data processing by considering the response of the chromatographic column to various sample introduction cycles or input functions. Correlation chromatography, which utilizes a random input, is explained in terms of multiplex methods and decorrelation techniques for unscrambling the chromatogram, including Fourier and Hadamard techniques. The text then concentrates on the ‘added value’ of using algorithms to modify the sample introduction time sequence to achieve multidimensional and multiplex chromatography. This is illustrated by a thorough explanation of two-dimensional chromatography utilizing multiple injection and column switching techniques.‘a fascinating account of the other side of gas chromatography’ A description follows on the hardware required to carry out multiple input chromatography and contains two sections: the computer system and the chromatographic instrumentation. A basic set-up for a ‘computerized chromatography system’ is discussed in detail including details of various sample intro- duction methods and apparatus ranging from simple injection and pyrolysis reactors to exponential dilution techniques and diffusion cells, with a short overview of the computer system. Practical aspects are illustrated by considering two application areas: thermochromatography and, briefly, environmental analysis.Thermochromatography or pyrolysis gas chromato- graphy looks at the analysis of gases evolved from pyrolysis of samples, particularly polymers, and includes comments on various approaches to polymer characterization. Having considered the mathematics, chemometrics, hard- ware and applications the authors round off the book with three appendices for those who have mastered the nitty gritty of the main chapters. These are in-depth explanations, equations and listings relating to matrix algebra, fast Hada- mard transforms and correlation chromatography, the algor- ithms being in BASIC. I found the book a fascinating account of ‘the other side of gas chromatography’ and can recommend it to those with a scant knowledge of the subject and for readers who require a ‘review-plus’ treatment, the plus being details of the principles behind the various approaches to multiple input chromatography. It is well written with plenty of references for further reading, thus catering for those readers seeking baptism by fire and the more initiated who want an in-depth treatment of the main aspects of the technique.A. Braithwaite Mass Spectrometry. Volume 10 Senior Reporter M. E. Rose. Specialist Periodical Reports. Pp. xv + 431. The Royal Society of Chemistry. 1989. Price f95.00. ISBN 0-851 86-348-5. Volume 10 of this excellent series covers the mass spec- trometry literature between July 1986 and June 1988. Eleven chapters are included with 3390 references cited. The chapters cover fundamental studies, organic, inorganic and biochem- ical applications, mixture analysis and instrumentation. The senior reporter is to be congratulated in obtaining such a broad coverage of the area.He has also taken care that topics which have not been covered before in the series such as high temperature studies are included. The various authors, who bring considerable experience and expertise to the task, have gone about the difficult task of presenting the wealth of information available to them in different ways. This ranges from a structured listing of the complete work published in an area during the period, enabling the reader to find information relevant to their own interests efficiently, to a more detailed review of the totality of the work carried out indicating the major conclusions and citing the most influential papers.Both these approaches have their attractions, but, in a series that is of necessity a snapshot of the literature in what is a very fast moving area, it is likely that the more judgmental approach will stand the test of time a little better. In order to compete with the increasingly sophisticated forms of computer search- ing now available the use of the experience and expertise of the reviewing author to act as a filter in selecting the most important of the vast numbers of papers that have been published in an area will be a major consideration. The choice of the senior reporter to select an area for natural products (here nucleosides, nucleotides and nucleic acids) is a good one enabling a detailed rather than a very broad coverage.The chapters that have the greatest challenge are those that deal with areas that change very rapidly making even the most astute of predictions often wide of the mark. Those that cover more mature parts of the wide science base of the technique are more able to sum up the work carried out. The use of camera-ready copy, to be expected in a volume under as many time constraints as this one, is acceptable but does lead to varying typefaces and typesize, which can be a little distracting. One of the advantages of this method is, however, the inclusion of a subject index, which is extremely useful. In conclusion, the volume is to be warmly welcomed and recommended to all laboratories seriously interested in mass spectrometry research. To those scientists whose area of research is among those specifically covered the publication is clearly essential but it is also to be hoped that researchers in other areas will find information and discussion relevant to their own area of work.J . H . Scrivens Chemical Sensors and Microinstrumentation Edited by Royce W. Murray, Raymond E. Dessey, William R. Heineman, Jiri Janata and W. Rudolf Seitz. American Chemical Society Symposium Series 403. Pp. xii + 410. American Chemical Society. 1989. Price US$89.95 (USA and Canada); US$107.95 (Export). ISBN 0-841 2-1 661 -4. This book, one in the well known American Chemical Society Symposium Series, is based on the papers presented at the 196th National Meeting of the American Chemical Society held at Los Angeles in 1988. Although a camera-ready format is adopted, the collection of papers is supported by a very comprehensive and useful subject index.The symposium, an amalgamation of two symposia proposed to cover modern chemical sensors and microinstrumen tation , respectively, is led from the chemical sensing aspect. The 25 papers include many of the best known experts in the field of chemical sensors and biosensors amongst the authors. Indeed, a glance at the five editors should inspire confidence that this is a significant work. A useful and well-referenced overview by Murray sets the scene for the papers, which are categorized as being concerned with sensors based on electrical, mass or thermal, and optical84N ANALYST, JULY 1993, VOL. 118 measurements. Each section is also preceded by a brief, but pertinent, introduction.The overall impression of this text is that it is a demonstration of the maturation of sensor research, with each expert showing just how far work has progressed since the early days of sensors in the late 1970s. In this respect, the book is a milestone in sensor development. Dominant themes include membrane and film-based sensors and asso- ciated materials technology. Biosensing as defined by the substrates is also prevalent amongst the papers. ‘specificity at the expense of generality’ As with any text based upon a collection of symposium papers, there is often specificity at the expense of generality. For example, Meyerhoff‘s interesting paper entitled ‘Poten- tiometric sensors’ devotes much of its content to the measure- ment of anions using sensors based on metalloporphyrins.In contrast, an equally fascinating paper by Hill entitled ‘Bioelec- trochemistry at microelectrodes’ majors on band microelec- trodes, but devotes sufficient space to include useful reference to other microelectrode devices. Overall, sensing technology based on potentiometric, amperometric, surface acoustic wave, piezoelectric bulk resonators, fibre optic and optical waveguide devices is covered in the book. It was a surprise that relatively little was reported on the development of sensor arrays, with only two papers being reported: one by Wohltjen using an array of four surface acoustic wave sensors, and one by Giuliani who describes a multi-element optical waveguide sensor array. This book is a specialist text, but nonetheless should appeal to a wide readership in the rapidly expanding field of chemical sensors, biosensors and microinstrumentation.The cost of this book is likely to be prohibitive for many who would benefit from its contents, particularly postgraduate students who are working in the field of sensing. This, however, is an inevitable feature of any specialist text of this type. P. R. Fielden Wilson and Wilson’s Comprehensive Analytical Chem- istry: Volume XXIV. Energy Dispersive X-ray Fluores- cence Analysis Edited by G. Svehla. Pp. xx + 431. Elsevier. 1990. Price US$215.50; DF1420.00. ISBN 0-444-98897-1. It is the self-stated aim of this book ‘to present, in a concise manner, the physical principles and technical aspects of energy dispersive X-ray fluorescence (EDXRF) analysis and to survey its applications’.In fact, I felt that the book, with 14 chapters and 431 pages, dealt with the subject more in a comprehensive than concise manner. The chapters are arranged conventionally and take the reader through Fun- damentals of XRF, Excitation, Secondary Radiation from Samples, Detection then via aspects of the spectrometry and quantification to Applications. Overall the clarity of the descriptions in the Fundamentals section has much to recommend it. It is refreshing to see an author concentrating on photon excitation and also consider- ing energies up to the K lines of the transuranic elements. On the debit side, the source of data in the mass absorption coefficients and line intensity tables was not quoted, which substantially reduces their usefulness. The description of radioisotope sources in the Excitation chapter is very comprehensive.This is an area infrequently or only briefly covered elsewhere and is a particularly valuable contribution. Unfortunately, this complete coverage of radio- isotope systems is very much at the expense of the use of low- power X-ray tubes. The author is unduly concerned with the stability of X-ray tube excitation, which likely reflects the position in Eastern Europe in 1978 (the date of the original Polish text) and is not in tune with current practice. The chapter on Secondary Radiation is disappointing and lacks the clarity often found in treatments describing the fundamental parameter approach. The Detector and Spec- trometry chapters, like the one on Excitation, concentrate on the technology used in benchtop radioisotope-excitation , proportional counter analysers.The coverage of these systems is both comprehensive and excellent but that of contemporary semiconductor detection systems is poor and rather dated. ‘a high degree of readability’ The Selection of Conditions chapter in fact concentrates on analytical calibration, which it covers very well. This is to miss an opportunity to give much-needed guidance on the selection of excitation kV, filters and secondary targets in tube-excited systems. Matrix effects and their correction are covered in considerable (but very readable) detail including a section on particle size effects, which is more comprehensive than any I know and is highly recommended.It is very gratifying to find a whole chapter devoted to Sources of Error, including details on line overlap and background calculation methods and a treatment of detection limits which closely follows that of Currie. The last four short chapters cover a variety of applications. Of particular note is the chapter on Geological Prospecting and Mining, which covers the important topics of field analysis and XRF logging in boreholes and the chapter entitled On- stream Analysis. In general, 1 found the sparing use of italicized keywords and phrases added to the high degree of readability. The translation is first class, the reference list wide (although a little dated) and the overall presentation quality good. Despite the drawback arising from a lack of coverage of contemporary X-ray tube excited, semiconductor detector systems this important book deserves a place in the analytical chemistry section of any library and is essential reading for anyone wanting to know what makes the ever-popular benchtop EDXRF machine tick.A. T. Ellis Liquid Chromatography/Mass Spectrometry. Tech- niques and Applications By Alfred L. Yergey, Charles G. Edmonds, lvor A. S. Lewis and Marvin L. Vestal. Modern Analytical Chemistry. Pp. ix + 306. Plenum Press. 1990. Price US$65.00. ISBN 0-306- 431 86-6. The stated objective of this book is to be of use to people who are beginning to use the techniques as well as more experienced practitioners. Techniques and applications of current importance are to be described while not neglecting descriptions of approaches that may be of significance in the future. These are laudable ideals; however, the book has suffered more than any I can recall in the recent past from the, often rapid, progress of science.After an introduction to the area the book describes three technique areas in some detail, these are: direct liquid introduction, mechanical transport and thermospray. The then new approach of particle beam is covered briefly in two pages. There then follows three applications chapters covering the LC-MS of nucleic acids, conjugated molecules and approaches in amino acids, pep- tides and proteins. A detailed bibliography follows covering the literature to May 1988. There is a very good practical treatment of the techniquesANALYST, JULY 1993, VOL.118 85N covered; this is a very fast moving field, however, and the newer techniques of particle beam (covered here briefly) atmospheric pressure chemical ionization and electrospray have become widely used subsequent to the publication of this book. As a consequence of these developments the book can now only be recommended as part of a more general study of LC-MS methods or to those people with a specific interest in the technique areas described. There is a need for a text in this area, which is growing in importance, and these shortcomings could possibly be overcome by an updated text. The applications chapters are very heavily biased in favour of biochemical methods although this is not clear from the title, or indeed, the introduction. Those readers with an interest in non-biological separations will find little here to help them specifically although the general principles described may be useful.Owing to the technical advances already mentioned and other relevant developments such as matrix assisted laser desorption (MALD) some of the comments made in the book can now be misleading. In the chapter on thermospray for example the indication is given that thermospray might be the technique of choice in the determination of peptide molecular mass. This would now be much better obtained using electrospray or MALD coupled with a time-of-flight analyser. In conclusion, there is much to admire in this book taken as a snapshot in time. It treats an important area well, covering what were then the major methods and combining practical advice with a detailed bibliography.The emphasis on bio- chemical methods is not identified in the title but perhaps reflects the major spread of interest in the area. The rapid advances made in this area, however, have made the book largely a historical document of interest mainly to people with a specific need for one of the techniques described or for those with an interest in seeing how fast an area can develop. The need for a text covering this area is still present but the fast moving nature of the field makes the timing of an update or new publication difficult. J. H . Scrivens Factor Analysis in Chemistry. 2nd edn. By Edmund R. Malinowski. Pp. xii + 350. Wiley. 1991. Price f43.70. ISBN 0-471 -53009-3. This is the second edition of a book first published in 1980.At the time of the initial publication the microcomputer revolu- tion had not yet occurred and most calculations were made on mainframe computers. In the intervening years very significant advances have been made in the area of chemometrics with work in experimental design, signal processing and other areas being carried out. This book, as did the earlier edition, concentrates on the area of factor analysis, here defined rigorously as a multivariate technique for reducing matrices of data to their lowest dimensionality by the use of orthogonal factor space and transformations that yield predictions and/or recognizable factors. A rather more approachable definition is also given in which the objective of factor analysis is defined as the development of a complete, physically meaningful, model for a data set.This combination of rigorous definition followed by the use of a simpler explanation is a feature of this book in which the context and meaning of the mathematical equations and algorithms used is always clearly explained. By judicious skipping one could obtain a clear overview of the principles and applications without needing to follow the detailed argument. This would be a waste, however, as the mathemat- ical concepts have rarely been better explained and a whole chapter is devoted to developing the complete details of a factor analysis calculation using model data. This gives the inexperienced reader the ability to use the computer programs later described, or those available elsewhere, with greater confidence.‘an excellent introduction to an important area of chemometrics’ The second edition has been very considerably updated. The notation has been changed to conform to current practice. A number of key approaches developed since the previous edition such as cross-validation and other methods for rank determination are described and there is a whole new chapter on special methods in factor analysis such as partial least squares, modelling methods and multimode factor analysis. Perhaps slightly disappointingly the applications chapters are largely unchanged although they do cover the basic applica- tion of the methods to practical problems. The book concentrates on the extraction of pure spectra, together with concentrations, from a data matrix of responses.The various approaches to obtaining the number of pure components are described clearly together with the most common methods of transforming the abstract solution to physically meaningful results. The effect of experimental error on target factor analysis, which complicates the application of these methods considerably is treated in some depth detailing how errors affect the various factor analysis steps. Among the various technique areas described are absorption and emission spectroscopy, chromatography, mass spectrometry and nuclear magnetic resonance spectroscopy with biomedical and environmental applications among those covered. Appen- dices cover FORTRAN programs, written by the author, which enable many of the calculations described to be made.In addition, programs written in MATLAB, a useful, but rather expensive, program system are given. There is also a worthy, but rather out-of-date, bibliography with no books listed after 1978. In conclusion, the book is an excellent introduction to an important area of chemometrics with detailed explanations of basic principles. The original book has been updated to take new approaches into account and a wide range of examples are given. This could be usefully updated although all the main areas are covered. The book can be recommended warmly as part of a general chemometric course or as an aid to analytical chemists or spectroscopists in data analysis. J. H. Scrivens PCs for Chemists Edited by J. Zupan. Data Handling in Science and Technology 5.Pp. xvi + 212. Elsevier. 1990. Price US$lOO.OO; Df1195.00. ISBN 0-444-88623-0. The ubiquitous personal computer has become what might be called the third generation tool €or the analytical chemist, that is, after log tables and calculators. However, the PC is a versatile tool capable of being used for much more than number crunching, for example , data analysis using spread- sheets, information organization and archiving, report genera- tion using word processors and drawing and graphics pack- ages. The chemist is now able to collect raw data from instruments, port this into a spreadsheet, carry out calcula- tions, and data analysis, construct databases and produce graphs. These data can then be incorporated into a report produced on a word processor. This may seem a lengthy procedure and to many that will be the case.However, with a little time and careful planning it is surprising how quickly one can achieve excellent results. Help and ideas are always valuable and PCs for Chemists is such a text. The book is a collection of chapters by various authors whose remit it seems was to write a comprehensive account of86N ANALYST, JULY 1993, VOL. 118 the capabilities and applications of a specific software area. Thus, we have ten chapters on mainstream applications such as word processing, databases and spreadsheets, whilst other chapters have a more specialized appeal, for example programming databases, networks and data acquisition. The first chapter on the use of word processors illustrates the general approach followed throhghout the book, that is, a general introduction to the terminology and capabilities of the software followed by applications.Chapter 1 is in fact a short yet thorough introduction to report and document production and includes details on fonts, graphics and scientific equations and symbols. There follows an extensive chapter on databases and spreadsheets. DBASE 111 is used to illustrate database applications using an atomic absorption procedure for analys- ing thallium samples as an example. Programming procedures are used to produce a macro to handle data entry and prompts. A similar approach is followed for Lotus 1-2-3 where a spreadsheet is developed to collate data from a series of experiments to test the ruggedness of the analytical proce- dure. A similar theme is continued in the next chapter where programming chemical databases is considered.Procedures for representing and handling chemical structures are dis- cussed in terms of a connectivity matrix and connection table. Spectra representation and peak tables are also considered. Techniques for extracting information from a database highlight the complexities involved in efficiently searching large databases. It is appropriate, therefore, that a discussion follows on handling large numbers of multivariate data. Two techniques are explained: fast Fourier transform and fast Hadamard transforms. A look at developing expert systems using PROLOG shows the steps involved in developing a database and the systematic rules required. This is illustrated using data from a chromatographic separation of drugs.The final group of chapters focus on hardware aspects by surveying the basic principles of data acquisition and network- ing. The stated aim of presenting an overview is achieved and the reader should be well equipped to discuss requirements with hardware designers and appreciate the contents of instrument manuals. A varied and interesting book covering a wide range of topics. There is sufficient detail for the reader to consider using a PC for additional applications. A . Bruith waite Handbook of U.S. Colorants. Foods, Drugs, Cosmetics, and Medical Devices. Third Edition By Daniel M. Marmion. Pp. xii + 574. Wiley. 1991. Price f71 .OO. ISBN 0-471-50074-7. If this text were solely concerned with the uses of colourants in foods it would be tempting to call it a cook-book.The text is divided into three parts, the first of which deals with the history, regulation and use of colourants, the second with colourant analysis and the third with the resolution of mixtures and the analysis of commercial products. The first part opens with a brief history and lists the permitted colourants. Then follows a brief chapter concerned with areas of use and an equally brief chapter on regulations governing use. Next there is a much longer chapter, containing a lot of tabular information, about the certified colours. Basic chemical information is presented, including structural and molecular formulae. The concluding chapter of this section is concerned with colourants exempt from certification.Each of these is accorded a few hundred words of information about chemical composition (many are of natural origin) and use. Interestingly enough, the list of miscellaneous colourants not requiring certification includes lead acetate. An appendix then lists colourant specifications, including the maximum toxic heavy metal content. Three further appendices list some US suppliers (about 20 companies), provides a glossary of terms and a two-page guide to obtaining the listing by the FDA of a proposed new colour additive, respectively. The second part of the book opens with a chapter concerned with identification. The bulk of this chapter is taken up with reproduction of the instrument output from the most charac- teristic qualitative procedure and includes UV-visible spectro- photometry (some of the spectra have percentage trans- mission as the ordinate), proton NMR, and some DSC traces (the instrument and operating conditions are specified).The next chapter is entitled ‘Determination of Strength’. Strength would appear to mean percentage purity of the major component and some standard titrimetric, gravimetric and spectrophotometric methods are described. The chapter also includes a discussion of the use of assay by determination of the organic S, N or halogen content. A two-page chapter on the determination of insoluble matter is followed by one concerned with the inorganic salt content. Ion chromato- graphy is the recommended procedure, but most of the chapter is devoted to spectrophotometric, gravimetric or titrimetric procedures.The following chapter on metals contains the statement that ‘the battery of techniques in use today for the determining metals ranges from the classical to the ultramodern and includes such procedures as the Gutzeit techniques for arsenic, atomic absorption spectroscopy . . . and X-ray fluorescence’. It is curious to see flame AAS categorized as a ‘newer instrumental method’. However, Marmion does acknowledge that methods involving chemical vapour generation, electrothermal atomization and the use of the ICP should all be useful, but indicates that there would appear to be little in the way of published work so far. The procedures detailed in this chapter have a rather old-fashioned feel to them. The next, equally short, chapter deals with organic im- purities. This chapter is really a broad overview and does not attempt to provide details of methods. These are provided in the two subsequent chapters, which deal with ‘Uncombined Intermediates and Other Low Molecular Weight Impurities’ and ‘Homologous, Isomeric and Other Related Colorants’, respectively. The first of these chapters provides details of a number of methods involving primarily HPLC and visible spectrophotometry . The second chapter contains almost exclusively chromatographic methods including a consider- able number of planar chromatography methods. The first chapter in the third part of the book, ‘Resolution of Mixtures’, is some 35 pages of annotated bibliography presented in alphabetical order with respect to the first named author. The following chapter, ‘Analysis of Commercial Products’ adopts much the same format. The chapter is divided into sections dealing with baked goods, beverages, candy and confections, cosmetics, dairy products, drugs, fats and oils, fruits, grain and grain products, jams and jellies, meat and fish, spices and condiments and concludes with a general section. The authors cited include at least two past presidents of the Analytical Division of the RSC, and, who knows, maybe one or two future Presidents. In addition to the references provided in these last two chapters, each of the preceding chapters is fully referenced. The dates of these show that there has been little relevant work published recently, a comment made by the author and alluded to earlier in connection with the use of atomic spectrometry for the determination of metals. The index is first rate. There is no doubt that this manual serves its purpose well and provides an excellent starting point for anyone with an interest in the nature of, the determination of and/or the analysis of colourants. The text would also act as an extremely useful source-book for anyone contemplating the devising of teaching experiments concerned with aspects of colourants in commercial products. Juliun F. Tyson

ISSN:0003-2654    

DOI:10.1039/AN993180081N

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

ANALYST, JULY 1993, VOL. 118 87N Conference Diary Date Conference August Location 9-1 1 9-1 3 9-13 19 22-25 22-27 22-27 22-27 23-27 23-27 23-27 23-27 26-1 J9 29-319 30-419 3rd Soil and Sediment Residue Analysis Winnipeg, Workshop Manitoba, Canada Asianalysis 11: Second Asian Conference on Analytical Chemistry China Changchun, ILC '93: International Conference on Luminescence and Optical Spectroscopy on Condensed Matter Rocky Mountain Chapter Annual Symposium Storrs, CT, USA Arvada, CO, USA EUROTOX'93 (32nd Congress of Toxicology) Uppsala, Sweden Gordon Research Conference on Reactive Polymers, Ion-exchangers and Adsorbents USA Newport, RI, 206th ACS National Meeting (with Sessions of the Divisions of Analytical Chemistry, Environmental Chemistry, Chemical Health and Safety, etc.) Third International Symposium on Separation Technology Belgium Chicago, IL, USA Antwerp, 9th Meeting of EURO CVD Tampere, Finland 9th International Conference on Fourier Calgary, Transform Spectroscopy Alberta, Canada 6th Hungardtalian Symposium on Lillafured, Spectrochemistry , Advances in Environmental Sciences 9th Danube Symposium on Chromatography Hungary Budapest, Hungary 5th International Conference on Electron Spectroscopy Ukraine 9th International Symposium: Advances and Application of Chromatography in Industry Kiev, Bratislava, Czechoslovakia 13th European Conference on Surface Science Warwick, UK Contact Dr.G. R. Barrie Webster, Pesticide Research Laboratory, Department of Soil Science, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2. Tel: + 1 204 474 6039.Fax: + 1 204 275 6019; or Professor Dr. Joseph Tarradellas, IGE, Federal Technical Institute EPF-L, CH-1015 Lausanne Ecublens, Switzerland Professor Erkang Wang, Asianalysis 11, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, P.O. Box 1022, Changchun, Jilin 130022, China Tel: +86 431 682 801 (ext. 562). Fax: +86 431 685 653 Professor Douglas Hamilton, Physics Department, 2152 Hillside Road, University of Connecticut, Storrs, CT 06269-3046, USA Tom Christensen, University of Colorado, Physics Department, P.O. Box 7150, Colorado Springs, CO Tel: + 1 719 593 3130. Fax: + 1 719 593 3542 Dr. R. A. Ettlin, EUROTOX Secretary General, Sandoz Pharma Ltd., Toxicology, Building 881, P.O. Box, CH-4002 Basle, Switzerland Professor Cs.Horvhth, Department of Chemical Engineering, Yale University, P.O. Box 2159, Yale Station, New Haven, CT06520, USA Tel: + 1 203 432 2217. Fax: + 1 203 432 4360 Mr. B. R. Hodson, American Chemical Society, 115516th Street N.W., Washington, DC 20036, USA Tel: + 1 202 872 4396. Mrs. M. Stalmans, University of Antwerp (UIA), Department of Chemistry, Universiteitsplein 1, B- 2610 Antwerp-Wilrijk, Belgium Tel: +32 3 820 23 75. Fax: +32 3 820 23 74 Ms. Raili Siekkinen, Tampere University of Technology, P.O. Box 527, SF-33101, Tampere, Finland Lois Kokoski, Conference Office, The University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4 Tel: + 1 403 220 5051. Fax: + 1 403 284 5696 Dr. Gy. Zaray, Institute of Inorganic and Organic Chemistry, Eotvos University, P.O.Box 32, H-1518 Budapest 112, Hungary Professor L. Szepesy, Hungarian Chemical Society, Budapest, Hungary Tel: +36 1 186 9000. Fax: +36 1 181 2755 J. J. Pireaux, LISE, rue de Bruxelles, 61, B-5000 Namur, Belgium Assoc. Prof. Jozef Polonsky, Department of Analytical Chemistry, Slovak Technical University, Radlinskeho 9,812 37 Bratislava, Czechoslovakia Tel: +42 7 560 43. Fax: +42 7 49 31 98 Dr. C. F. McConville, ECOSS-13, Department of Physics, University of Warwick, Coventry, UK CV4 7AL Tel: +44 203 523353. Fax: +44 203 692016 80933-7150, USA88N ANALYST, JULY 1993, VOL. 118 Date Conference Location Contact 30-1/9 15th International Symposium on Safety in Lugano, Interaction with Quality, Productivity and Economy 30-2/9 Second European Conference on Near Infrared Kolding, Spectroscopy Denmark Switzerland Secretariate ISSA, Section Chemistry, c/o BG Chemie, P.O.Box 10 14 80, D-W-6900 Heidelberg 1, Germany Lone Vejgaard, Biotechnological Institute, Holbergsvej 10, P.O. Box 818, DK-6000 Kolding, Denmark Tel: + 45 75520433. Fax: + 45 75529989 J. Barek, Department of Analytical Chemistry, Charles University, Albertov 2030,12840 Prague 2, Czechoslovakia Tel: +42 2 292051, +42 2 297541. Fax: +42 2 291958 31-1/9 106th Annual International Meeting and Prague, Exposition of AOAC International Czechoslovakia September 2nd UK International Meeting on Biological and Biomedical Applications of Scanning Probe Microscopy Nottingham, UK The SPM Laboratory, Department of Pharmaceutical Sciences, University of Nottingham, Nottingham, UK NG7 2RD Tel: +44 602 515101.Fax: +44 602 515102 The Conference Secretary (RE), Department of Chemical Engineering, The University of Leeds, Leeds, UK LS2 9JT Professor Th. Theophanides, National Technical University of Athens, Department of Chemical Engineering, Zogratou 15780, Athens, Greece Dr. Shang-Shyng Yang, Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan 106, Republic of China; or Dr. Domy C. Adriano, University of Georgia, Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802, USA Miss P. E. Hutchinson, Analytical Division, The Royal Society of Chemistry, Burlington House , Piccadilly , London, UK W1V OBN Tel: +44 71 437 8656. Fax: +44 71 734 1227 Professor D. J. A. Crommelin, FIP Congress Department, The Hague, The Netherlands Tel: +3170 363 1925.Fax: +3170363 3914 Professor T. J. Parker, Department of Physics, University of Essex, Wivenhoe Park, Colchester, UKC04 3SQ Dr. Juan JimCnez, Drip 5, Universidad de Valladolid, 47011 Valladolid, Spain Professor J. Fraissard, Laboratoire de Chimie des Surfaces, Universitd P. et M. Curie, 4, Place Jussieu (Boite 196), 75252 Paris Cedex 05, France Dr. Bernhard Bliimich, c/o Max Planck-Institute fur Polymerforschung, Postfach 3148, D-6500 Mainz, 2-3 5-10 5-10 5-10 5-1 1 5-1 1 6-10 6-10 6-10 6-10 7-8 7-10 7-12 8-10 Ninth International Biodeterioration and Biodegradation Symposium Leeds, UK 5th European Conference on the Spectroscopy of Biological Molecules Lontraki, Greece Second International Conference on the Biogeochemistry of Trace Elements Taipei, Taiwan, Republic of China Euroanalysis VIII: European Conference on Analytical Chemistry Edinburgh, UK Pharmacy World Congress '93 Tokyo, Japan 18th International Conference on Infrared and Millimetre Waves Colchester , UK Defect Recognition and Image Processing in Semiconductors and Devices 1 lth Specialised Colloque Ampere on Magnetic Resonance in Homogeneous and Heterogeneous Catalysis Second International Conference on Magnetic Resonance Microscopy Santander, Spain Menton, France Heidelberg, Germany Germany Environmental Fate of Chemicals Lancaster, UK Verona and Soave , Italy Dr.D. Osborn, Institute of Terrestrial Ecology, Monks, Abbots Ripton, Huntingdon, UK PE17 2LS Dr. Franco Tagliaro, Scientific Secretariat, c/o Istituto di Medicina Legale, Policlinico Borgo Roma, 1-37134 Verona, Italy Tel: +39 45 8074 618.Fax: +39 45 505 259 12th International Symposium on Biomedical Applications of Chromatography and Electrophoresis and 2nd International Symposium on the Applications of HPLC in Enzyme Chemistry 12th International Symposium on Microchemical Techniques Cordoba, Spain Professor M. Valcarcel, Quimica Analitica, Facultad de Siencias, 14004 Cordoba, Spain Tel: +34 57 234453. Fax: t-34 57 452285 M. Frei-Hausler, IAEAC, P.O. Box 46, CH-4123 Allschwil2, Switzerland Tel: +4161632789. Fax: +4161482 08 05 4th Workshop on Chemistry and Fate of Modern Pesticides and Related Pollutants Prague, CzechoslovakiaANALYST, JULY 1993, VOL. 118 89N Date 8-1 1 9-15 11-15 12-15 12-17 13-17 13-17 19-22 19-22 20-24 20-26 21-22 21-23 22-24 26-1/10 26-1/10 26-1/10 Conference Location 14th International Symposium on Polynuclear Aromatic Hydrocarbons USA Tan-Tar-A, MO, ISEC '93, International Solvent Extraction Conference: Solvent Extraction in the Process Industries EIRELEC 1993: Electrochemistry to the year 2000 Limerick , Surfaces in Biomaterials '93 York , UK Adare , Co.Ireland Cambridge, MA, USA 9th International Conference on Heavy Metals in the Environment Canada Toronto, International Conference on Nuclear Analytical Methods in the Life Sciences Prague , Czechoslovakia Workshop in Liquid Scintillation Counting Loughborough, Leicestershire , UK 4th International Symposium on Chiral Montreal , Discrimination Quebec, Canada 2nd International Symposium on Planar Chromatography: Modern Thin-Layer Chromatography Dioxin 93: 13th International Symposium on Chlorinated Dioxins and Related Compounds Research Triangle Park, NC, USA Vienna, Austria 173rd Annual Meeting of the Swiss Academy of CH-1936 Natural Sciences (including Symposia of the Bagnes-Verbier, Swiss Society for Analytical and Applied Switzerland Chemistry, the Swiss Society for Microchemistry and Instrumental Analysis, the Swiss Association on Environmental Research, and other Societies, in German and French) 4th German Symposium on Near Infrared Spectroscopy Germany Essen , The Royal Society of Chemistry 1993 Autumn Meeting UK Warwick, XIIth Conference of Analytical Chemistry of Romania Romania Constanta, 15th International Nutrition Conference Adelaide, Australia 1993 European Workshop in Chemometrics Leuven, Belgium 12th Australian Symposium on Analytical Chemistry incorporating 3rd Environmental Australia Chemistry Conference Perth, Contact Professor E.Cavalieri, Epply Institute, Medical Center, University of Nebraska, Omaha, NE 68198- 6805, USA Tel: + 1 402 559 4090. Fax: + 1 402 559 4651 Conference Secretariat, SCI, 14/15 Belgrave Square, London, UK SWlX 8PS Tel: +44 71 235 3681. Fax: +44 71 823 1698 Professor M. R. Smyth, School of Chemical Sciences, Dublin City University, Dublin 9, Ireland Tel: +353 17045308. Fax: +353 17045503 ARDEL Management, P.O. Box 26111, Minneapolis, MN 55426, USA Tel: + 1 612 927 6707. Fax: + 1 612 927 8127 Heavy Metals Secretariat, CEP Consultants Ltd. , 26-28 Albany Street, Edinburgh, UK EH1 3QH Tel: +44 31 557 2478.Fax: +44 31 557 5749 Jan Kucera, Nuclear Research Institute, CS-250 68 Rez near Prague, Czechoslovakia Tel: +42 2 685 7831 ext. 2268. Fax: +42 2 685 7567 Dr. Peter Warwick, Nuclear Chemistry Laboratories, Loughborough University of Technology, Loughborough, Leicestershire, UK LEll3TU Tel: +44 509 222585. Fax: +44 509 233163 Chiral Secretariat, Conference Office, McGill University, 550 Sherbrooke St. West, West Tower, Suite 490, Montreal, Quebec, Canada H3A 1R9 Tel: + 1 514 398 3770. Fax: + 1 514 398 4854 Ms. Janet E. Cunningham, Barr Enterprises, P.O. Box 279, Walkersville, MD 21793, USA Tel: + 1 301 898 3772. Fax: + 1 301 898 5596 Symposium Secretariat, Dioxin '93 , Gesellschaft Osterreichischer Chemiker, Nibelungengasse 11 , A-1010 Vienna, Austria Tel: + 43 222 587 3980/4249.Fax: + 43 222 587 8966 General Secretary, Swiss Academy of Sciences, Barenplatz 2, P.O. Box 2535, CH-3001 Berne, Switzerland Professor Dr. H. W. Siesler, University of Essen, Schutzenbahn 70, P.O. Box 103764, D-4300 Essen 1, Germany Miss P. E. Hutchinson, Analytical Division, The Royal Society of Chemistry, Burlington House, Piccadilly, London, UK W1V OBN Tel: +44 71 437 8656. Fax: +44 71 734 1227 Dr. Gabriel-Lucian Radu, The Romanian Society of Analytical Chemistry, 13 Bul.Caro1 I, Sector 3, 70346 Bucharest, Romania Congress Secretariat, CSIRO Division of Human Nutrition, P.O. Box 10041, Gouger St., Adelaide 5000, South Australia, Australia Timshel Conference Service, J. B. Van Monsstraat 4, B-3000 Leuven, Belgium Tel: +32 16 290010.Fax: +32 16 290510 Valerie Landgrebe, Symposium Secretariat, 12AC/ 3EC, Conference and Seminar Management, IJWA Extension, The University of Western Australia, Nedlands, Perth, Western Australia 6009, Australia Tel: +619 380 3181/2433. Fax: +619 380 1088/106690N ANALYST, JULY 1993, VOL. 118 Date Conference Location Contact 27-29 Emerging Technologies in Hazardous Waste Atlanta, GA, Dr. W. Tedder, School Of Chemical Engineering, Management V USA Georgia Institute of Technology, Atlanta, GA 30332-0100, USA Tel: +1 404 894 2856. Fax: +1 404 894 2866 Symposium USA Inc., 814 North Grand Avenue, Covina, CA 91724, USA Tel: +1818 967 3869. Fax: +1 818 967 1861 Dr. Paul Illing, Health and Safety Executive, R425 L20 3QZ Tel: +44 51 951 3420.Fax: +44 51 922 7918 29 26th Annual Southern California Chapter Pasadena, CA, Tony Tumbrello, Associated Vacuum Technology 30 Duration of Repeated Dose Toxicity S t u d i e e Bath, A Commonsense Approach? UK Magdalen House, Stanley Precinct, Bootle, UK October 4-8 5-7 5-7 5-8 10-15 11-13 13 16-17 17-21 17-22 18-22 19-23 20-22 21-22 ECASIA 93,5th Conference on Application of Surface and Interface Analysis 34th ORNL-DOE Conference on Analytical Chemistry in Energy Technology Laboratory Exhibition and Conference 5th Meeting of the Nuclear Magnetism and Biology Group Electrochemical Society Meeting VIth National Symposium on Mass Spectometry FT Microscopy-10 Years On: 4th European Seminar on FT-IR Microscopy Second National Conference on Inductively Coupled Plasma Mass Spectrometry Eighth Symposium on Separation Science and Technology for Energy Application FACSS XX, 20th Annual Meeting of the Federation of Analytical Chemistry and Spectroscopy Societies Modern Electrochemistry in Industry and for the Protection of the Environment EXPOQUIMIA '93: Applied Chemistry Technical Fair Hygiene and Health Management in the Working Environment International Conference on Analytical Chemistry, Biochemistry and Pharmaceutical Sciences Catania, Italy Gatlinburg, TN, USA London, UK Toulouse, France New Orleans, LA, USA Dehradun, India Manchester, UK Detroit, MI, USA Oak Ridge, T N USA Detroit , MI, USA Krakow, Poland Barcelona , Spain Ghent, Belgium Casablanca, Morocco G.Marletta, Consorzio Catania Ricerche, V. Le Andrea Doria, 6,I-95125 Catania, Italy Tel: +39 95 221635.Fax: +39 95 339734 W. R. Laing, Technical Program Chairman, Oak Ridge National Laboratory, P.O. Box 2008, MS 6127, Oak Ridge, TN 37831-6127, USA Tel: + 1 615 574 4852. Fax: + 1 615 574 4902 Evan Steadman Communications Group Ltd., 90 Calverley Road, Tunbridge Wells, Kent, UK TN1 2UN Professor M. Malet-Martino, Laboratoire IMRCP, Universite Paul Sabatier, 118, route de Narbonne, F- 31062 Toulouse Cedex, France Electrochemical Society Inc, 10 South Main Street, Pennington, NJ 08534-2896, USA Dr. Pradeep Kumar, Indian Institute of Petroleum, Dehradun-248 005, India, and Dr. S. K. Aggarwal, Honorary Secretary-ISMAS, c/o Fuel Chemistry Division, Bhabha Atomic Research Centre, Bombay-400 085, Maharastra, India Michelle Barker, Conference Co-Ordinator, Spectra-Tech Europe Limited, Genesis Centre, Science Park South, Birchwood, Warrington, UK WA3 7BH Tel: +44 (0) 925 830 250.Fax: +44 (0) 925 830 252 Society for Applied Spectroscopy/ICP/MS Users Group, 198 Thomas Johnson Drive, Suite-2, Frederick, MD 21702-4317, USA Tel: + 1 301 694 8122. J. T. Bell, Oak Ridge National Laboratory, Post Office 2008, Oak Ridge, TN 37381, USA FACSS, 198 Thomas Johnson Drive, Suite S-2, Fredericks, MD 21702, USA Tel: + 1 301 846 4789. Fax: + 1 301 694 6860 Dr. Andrzej Kowal, Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapiminajek 1,30-239 Krakow, Poland Fira de Barcelona, Avda. Reina Ma Cristina, 08004 Barcelona, Spain 3rd International Symposium, 'Hygiene and Health Management in the Working Environment', c/o TI- K VIV, Attn.Ms. Rita Peys, Desguinlei 214, B-2018 Antwerp, Belgium Dr. V. M. Bhatnagar, Alena Chemicals of Canada, P.O. Box 1779, Cornwall, Ontario, Canada K6H 5v7 Tel: + 1 613 932 7702.ANALYST, JULY 1993, VOL. 118 91N Date Conference November 1-3 2 3 7-10 7-1 1 7-12 8-10 11-12 14-19 14-19 15-19 22-23 30-3112 Chernyaev Conference on Chemistry, Analysis, Technology and Application of Platinum Metals Electro-Membrane Processes Pharmaceutical Applications and Sample Handling Techniques Electrophoresis '93 7th International Forum-Electrolysis in Chemical Manufacture Symposium on Supercritical Fluid Phenomena (1993 Annual Meeting of the AIChE) International Symposium on Plasma Polymerizationhleposition International Conferences on Analytical Chemistry, Biochemistry, Pharmaceutical Sciences, and Water Quality/EnvironmentaI Pollution XV International Congress of Clinical Chemistry OPTCON '93 32nd Annual Eastern Analytical Symposium International Conferences on Analytical Chemistry, Biochemistry, Pharmaceutical Sciences, and Water QualitylEnvironmentat Pollution 13th International Symposium on HPLC of Proteins, Peptides and Polynucleotides Location Moscow, Russia London, UK York, UK Charleston, SC, USA Lake Buena Vista, FL, USA St.Louis, MO, USA Las Vegas, NV, USA New Del hi, India Melbourne, Australia San Jose, CA, USA New Jersey, USA Shanghai, China San Francisco, CA, USA Contact Dr. I. B. Baranovsky, Kurnakov Institute of General and Inorganic Chemistry, 31 Lenin Avenue, Moscow 117907, Russia Dr.T. R. Ralph, Johnson Matthey Technology Centre, Blounts Court, Sonning Common, Reading, Berkshire, UK RG4 9NJJ Tel: +44 734 722811 ext. 2257. Fax: +44 734 723236 Don Clark, Physical Sciences-265, Pfizer Central Research, Ramsgate Road, Sandwich, Kent, UK CT13 9NJ Tel: +44 304 616036. Fax: +44 304 616726 Mrs. Janet Cunningham, Electrophoresis '93, c/o The Electrophoresis Society, P.O. Box 279, Walkersville, MD 21793, USA Tel: + 1 301 898 3772. Fax: + 1 301 898 5596 Dr. N. Weinberg, 72 Ward Road, Lancaster, NY Tel: +17166840513. Fax: +17166840511 Michael A. Matthews, Chemical Engineering Department, University of Wyoming, Box 3295, University Station, Laramie, WY 82071-32, USA Tel: + 1 307 766 5769 Fax: + 1 307 766 4444. Or: Ted W.Randolph, Chemical Engineering Department, Yale University, 9 Hillhouse Avenue, New Haven, Tel: + 1 203 432 4375. Fax: + 1 203 432 7232 K. L. Mittal, Skill Dynamics (an IBM Company), 500 Columbus Ave., Thornwood, NY 10594, USA Tel: + 1 914 742 5747. Fax: + 1 914 742 5594 Dr. V. M. Bhatnagar, Alena Chemicals of Canada, P.O. Box 1779, Cornwall, Ontario, Canada K6H 5v7 Tel: + 1 613 932 7702. 1993 IFCC Congress Secretariat, 232 Bridge Road, Richmond, Victoria, Australia Tel: +613 429 4322. Fax: +613 427 0715 IEEELEOS, 445 Hoes Lane, P.O. Box 1331, Piscataway, NJ 08855-1331 , USA Tel: + 1 908 562 3896. Fax: + 1 908 562 1571 EAS Program Committee, P. 0. Box 633, Montchanin, DE 19710-0633, USA Dr. V. M. Bhatnagar, Alena Chemicals of Canada, P.O. Box 1779, Cornwall, Ontario, Canada K6H 5v7 Tel: + 1 613 932 7702.Ms. Paddy Batchelder, Conference Manager, 7948 Foothill Knolls Drive, Pleasanton, CA 94588, USA Tel: + 1 5 10 426 9601. Fax: + 1 5 10 846 2242 14086-9779, USA CT 06520-2159, USA December 7-9 The First Conference in Chemistry and its Doha, Professor Abdel-Fattah M. Rizk, Department of Applications Qatar Chemistry, Faculty of Science, University of Qatar, 8-10 Laser M2P, Materials Engineering, Medicine Lyon, Richard Moncorgk, Universite de Lyon 1, Bit. 205, P.O. Box 2713, Doha, Qatar and Biology, Physics and Chemistry France F-69622 Villeurbanne Cedex, France92N ANALYST, JULY 1993, VOL. 118 Date Conference 1994 January 10-15 1994 Winter Conference'on Plasma Spectrochemistry February 21-25 22-25 28-413 April 6-8 10-15 12-1 4 19-22 May 8-1 3 8-13 9-13 16-20 16-19 OFC '94: Optical Fibre Communications Conference HTC 3: Third International Symposium on Hyphenated Techniques in Chromatography Pittcon '94: The 45th Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy Electroanalysis: A Tribute to Professor J.D. R. Thomas 207th ACS National Meeting and 5th Chemical Congress of North America (with Sessions of Analytical Chemistry, Environmental Chemistry, Chemical Health and Safety, etc.) 13th Pharmaceutical Technology Conference ANALYTICA'94: 14th International Conference on Biochemical and Instrumental Analysis HPLC '94, Eighteenth International Symposium on Column Liquid Chromatography CLEO '94: Conference on Lasers and Electro-Optics Focus 94The Annual National Meeting and Exhibition of the Association of Clinical Biochemists 24th International IAEAC Symposium on Environmental Analytical Chemistry 24th Annual Symposium on Environmental Analytical Chemistry Locat ion San Diego, CA, USA San Jose, CA, USA Antwerp, Belgium Chicago, IL, USA Cardiff, UK Mexico City, Mexico Strasbourg, France Munich, Germany Minneapolis, MN, USA Anaheim, CA, USA Brighton, UK Ottawa, Ontario, Canada Ottawa, Canada Contact Dr.R. Barnes, 1994 Winter Conference on Plasma Spectrochemistry, % ICP Information Newsletter, Department of Chemistry, Lederle GRC Towers, University of Massachusetts, Amherst, MA 01003- 0035, USA Tel: + 1 413 545 2294. Fax: + 1 413 545 4490 Meetings Department, Optical Society of America, 2010 Massachusetts Avenue, NW, Washington, DC Tel: + 1 202 223 9034.Fax: + 1 202 416 6100 Dr. R. Smits, pla BASF Antwerpen N.V., Central Laboratory, Scheldelaan, B-2040 Antwerp, Belgium Tel: +32 3 568 2831. Fax: +32 3 568 3250 Mrs. Alma Johnson, Program Secretary, The Pittsburgh Conference, Department CFP, 300 Penn Center Boulevard, Suite 332, Pittsburgh, PA 15235, USA 20036-1023, USA Dr. J. M. Slater, Department of Chemistry, Birkbeck College, University of London, 29 Gordon Square, London, UK WClH OPP Tel: +44 7 I 380 7474. Fax: +44 71 380 7464 Mr. B. R. Hodson, American Chemical Society, 1155-16th Street N.W., Washington, DC20036, USA Tel: + 1 202 872 4396. Professor Mike Rubinstein, 13th Pharmaceutical Technology Conference, 24 Menlove Gardens North, Liverpool, UK L18 2EJ Tel: +44 51 737 1993. Fax: +44 51 737 1070 Miinchener Messe- und Ausstellungsgesellschaft mbH, Analytica '94lWerbung Postfdch 12 10 09, D- 8000 Miinchen 12, Germany Tel: +49 89 51 07 143. Fax: +49 89 51 07 177 Ms. J. E. Cunningham, Barr Enterprises, P.O. Box 279, Walkersville, MD 21793, USA Tel: + 1 301 898 3772. Fax: + 1 301 898 5596 Meetings Department, Optical Society of America, 2010 Massachusetts Avenue, NW, Washington, DC Tel: + 1 202 223 9034. Fax: + 1 202 416 6100 Focus 94, P.O. Box 227, Buckingham, Buckinghamshire, UK MK18 5PN Tel: +44 2806 613. Fax: +44 2806 487 Dr. James F. Lawrence, Food Additives and Contaminants, Health and Welfare, Tunney's Pasture, Ottawa, Ontario, Canada KlA OL2 Dr. M. Malaiyandi, CAEC, Chemistry Department, Carleton University, 1255 Colonel By Drive, Ottawa, Canada K1S 5B6 Tel: + 1 613 788 3841. Fax: + 1 613 788 3749 20036-1023, USA Entries in the above listing are at the discretion of the Editor and are free of charge. If you wish to publicize a forthcoming meeting please send full details to: The Analyst Editorial Office, Thomas Graham House, Science Park, Milton Road, Cambridge, UK CB4 4WF. Tel: +44 (0)223 420066. Fax: +44 (0)223 420247.

ISSN:0003-2654    

DOI:10.1039/AN993180087N

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

ANALYST, JULY 1993, VOL. 118 93N Conference Reports The 44th Pittsburg. Conference and Exhibition on Analytical Chemistry and Applied Spectroscopy, March 8-12, Atlanta, GA, USA Some of the Royal Society of Chemistry’s staff and some of this year’s 30000 visitors to the Pittsburg Conference and Exhibition on Analytical Chemistry and Applied Spectro- scopy, (PittCon) were stranded in Atlanta, Georgia, after a freak Winter storm roared up the Eastern US coast. PittCon had just wound down when the storm hit and brought with it up to 12 feet of snow in some areas, gale force winds, closing most East-coast airports and making roads impassable. At the opening ceremony six days earlier, Georgia Governor, Zell Miller had invited PittCon visitors to stay and enjoy the many attractions of Atlanta and to ‘spend money, we need it!’ Many attendees had little choice but to buckle down and stay tuned to ‘The Weather Channel’ for further news of the ‘Blizzard of ’93’ and its destructive progress.PittCon is the largest exhibition and technical programme of its kind in the world attracting over 1000 exhibitors displaying over 5 miles of the latest analytical instrumentation and over 1800 oral presentations in the form of symposia, poster sessions, short courses and mini-meetings. It is much more than an exhibition with lectures, it is a scientific phenomenon! A technological showcase of the fastest, most accurate and state-of-the-art instruments that science has to offer coupled with a fully comprehensive programme of symposia dealing with everything from the infinitessimality of precision measurement through to the more general topics of interest to Everyman’s chemist.PittCon has grown in size over its 44 year history leaving only a handful of US cities with facilities large enough to handle the influx. For the next few years, only Chicago, Atlanta and New Orleans are slated. It started out as a very small gathering of about a dozen exhibits and presented papers hosted by its current sponsors, the Society for Analytical Chemists of Pittsburgh and the Spectroscopy Society of Pittsburg and was held in none other than downtown Pittsburg, Pennsylvania. Since 1967 PittCon has ceased to be Pittsburg based but its premise to benefit science education still endures. In recent years, PittCon has donated half a million US dollars annually, the entire profit of the show.This year’s technical programme lacked lustre in its scope. Sorely missed were the Plenary lectures of previous years, always popular and well attended, and those topics that would normally arouse discussion and debate were few. Conferees looking for content though could not have been disappointed as it was there in abundance and some speakers were courageous in their efforts to amuse and impart a sense of fun and humour in their presentations. Gary Hieftje’s (Indiana University) presentation on ‘Spec- trometric measurements and instrumentation on the horizon’ was a particularly entertaining and enlightening talk on those indicators already in place that might determine future directions. It was included under the symposium title ‘Promis- ing Analytical Techniques on the Horizon’ and was dedicated to the memory of Professor L.B. (Buck) Rogers who pioneered developments in a wide range of analytical tech- niques including electrochemistry, separation techniques and spectroscopy. Hieftje suggested future paths that spectro- metric measurements and instrumentation might follow. Particularly that they will be more biologically oriented, use a greater range of dimensions, make better use of spatial resolution, have increased signal processing capabilities and useful diode lasers. The importance of data visualization will progress, for example, with ICP imaging to show three spatial dimensions for true 3D imaging. The impact of nanotechno- logy points to greater development of molecular level instrumentation and advancements being made now in semiconductor lasers suggest that these types of techniques may become routine and practical in the not too distant future.Hieftje also deduced that spectrometric developments cou- pled with the advancement of new technologies will mean that analytical instruments will be capable of examining a sample as it is being analysed, of tuning their own operating characteristics in order to optimize the sample characteriza- tion and therefore produce accurate analytical results during the initial sample examination. This year’s Maurice F. Hasler award was presented to Professor R. S. Houk, Senior Chemist at the Ames Labora- tory, US Department of Energy, for his work on the fundamental studies and application of plasma ion sources for mass spectrometry.His work has made contributions to ICPs, time-of-flight and ion-trap mass spectrometry. His award address entitled ‘Now for something completely different; the scientific impact of TCP-MS’ was certainly extraordinary in its presentation and very entertaining. Houk was able to show, with the aid of slides, that his career followed a similar path to that of Napoleon Bonaparte during the Napoleonic Wars! For example, he and Napoleon both began their careers with long hair! Environmental science, geochemistry and the nuclear A few of the many guests at the RSC reception at PittCon ’9394N ANALYST, JULY 1993, VOL. 118 The RSC stand at PittCon ’93 and semiconductor industries now make widespread use of the high sensitivity of ICP-MS but Houk feels there are several areas in which TCP-MS is underutilized.For example, stable isotope tracing of minerals in nutrition, particularly zinc and elemental speciation by ICP-MS using a nebulizer. Quality control and IS0 9000 preparedness is of current concern to all manufacturers and laboratories. A series of quality mini-meetings were held in order to answer some of these concerns. The symposium ‘Comparability and Traceabi- lity: An Aid to International Trade’ organized by Bernard King, UK Government Analyst and Deputy Director of the Laboratory of the Government Chemist, sct out to consider the crucial role that valid analytical measurements play in aiding and promoting international trade. Richard Worswick, UK Government Chemist, presented the European scene.The single trading area of Europe now reprcsents 40% of the world’s trade and 30% of the world’s production. The harmonization of standards and the establishment of reliable systems for testing and certification of products is of utmost importance to free trade within Europe and to exports world- wide. Worswick briefly described the organizations that have been set up to establish the mutual recognition and compara- bility of standards, namely the European Organization for Testing and Certification which was established in 1990 to promote voluntary mutual recognition agreements, The Commission of the European Communities through the EC measurements and testing programme which organizes and helps to fund projects needed to solve Community-wide measurement problems, The Western European Laboratory Accreditation Co-operation which was formed to harmonize the requirements for laboratory accreditation based on IS0 Guide 25 and EURACHEM which promotes international agreement and collaboration on issues which affect the quality of measurements in chemical analysis.The president of the Analytical Division of the RSC, Ernie Newman, presented the advantages of laboratory accredita- tion in the UK, the pitfalls that can bc encountered during the accreditation process and the benefits to laboratory personnel in terms of confidence and to the laboratory in increased business once accreditation is achieved. His talk was entitled, ‘The Advantages of Accreditation: a Laboratory Manager’s View’.Meanwhile, the madding crowds were being courted in the exhibition halls with the most impressively packaged techno- logy and slick advertising slogans. The driving force behind most of the latest technology continues to rely heavily on advancements and miniaturization of electronics which trans- lates into faster analysis times and greater flexibility to switch from one analytical technique to another. Developments in computer hardware and software and how these interact have made great strides in data handling and data visualization. Instrument component manufacturers too are having a greater influence on the final product as are those companies involved in sample preparation technology. Microwave heating of samples for example has come a long way in the last ten years from being experimental to a routine, automated method.Also, for some time now, the traditional laboratory instru- ment manufacturers have been busy making their systems more suitable to harsher environments; taking them from the laboratories into industry for process and on-line monitoring and that trend still continues although the laboratory instru- ment still reigns supreme. The Royal Society of Chemistry’s function at PittCon is three-fold: as an exhibitor, promoting its books, journals and databases produced by Information Services; as a host, of an evening reception given each year to thank those US chemists who purchase, contribute to and referee for the Society’s publications; lastly, PittCon provides the RSC with editorial material, potential ideas and authors for books and journals and advertising and gives the marketing personnel the opportunity to come face to face with their customers.Next year, PittCon will be held in Chicago, Illinois, at the end of February and is being billed as the ‘Greatest Science Show Ever’. Whether its greatness will be a measure in linear feet of exhibition space or specific gravity of precipitation remains to be seen! Andrea Bedson PittCon Mini-report Symposium on the lmmunoanalysis of Food Safety This symposium on the whole was very interesting and of particular interest to those of limited exposure to immuno- assay procedures as judged by the questions asked. Richard Durst set the scene on the concepts of immunoassays followed by Jeanette Van Emon and Mary Trucksess who described how the technique has been used in environmental and food monitoring agencies.Finally Rosalyn Y alow discussed some aspects of over- sensitivity of assays. Richard Durst of Cornell University chaired the symposium and gave the first lecture on the immunological concepts and assay techniques. The lecture was targeted at people with limited immunoassay knowledge. The historical background and development of immunoassays were discussed starting with the original work of Berson and Yalow. Durst then went on to discuss the different immunoassay formats and labelling procedures together with the terminology normally associated with them. Jeanette Van Emon of the United States Environmental Protection Agency (EPA) described how immunoassays had been implemented into EPA monitoring programmes.She stressed the importance of the development of simple immunoassay test kits for pesticides ( e . g . , parathion and polychlorinated biphenyls) for use by individuals not trained in analytical methods. Such kits have been used by personnel in the United States army to assess the suitability of drinking water in streams. She also presented data on the correlation of analyses between the immunoassay based methods and GC- MS for the monitoring of pesticides and herbicides. The overall correlation was about 0.92. Mary Trucksess from the United States Food and Drug Administration (FDA) focused on the simplicity, speed andANALYST, JULY 1993, VOL. 118 9SN considerable cost advantages of immunochemical methods in food analysis compared with other methods.She also des- cribed the different types of toxins present in food, their source, their effect on humans and immunoassays that have been developed to monitor them both (qualitative and quantitative). A. P. F. Turner from the Cranfield Institute of Technology continued the theme of immunoassays in food analysis. He described numerous technologies used to measure or enumer- ate micro-organisms, e.g. , impedance and mass and refractive index biosensors. He also discussed the advantages of using disposable dipsticks as sensors in food analysis. The final lecture was presented by the distinguished Nobel Prize winner Rosalyn Yalow entitled ‘The Problems with Oversensitivity’. Dr. Yalow described the work she carried out with Berson in the late 1950s which led to the development of radioimmunoassays (RIA). She talked about the sensitivity achieved by her group in the early years, typically 1 x 1 x 1O-I2 mol 1-l concentrations of peptide hormones and compared it with the sensitivity obtained today. She stated that it was possible to measure picogram amounts of chemicals in the presence of billion-fold higher amounts of other substances and then posed the question whether it was wise to develop and use such assays. The question was answered by stating the ‘Delaney clause’ of 1959, which prohibits the presence of any food additive at any dose level that produces cancer in any animal even at the maximum tolerated dose. Dr. Yalow concluded the lecture by stating the need for develop- ing very sensitive assays if the ‘Delaney clause’ is to be adhered to. Derek Palmer Loughborough University of Technology

ISSN:0003-2654    

DOI:10.1039/AN993180093N

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

ANALYST, JULY 1993, VOL. 118 9SN Future Issues will Include- Dynamic Model of an Optical Absorption-based pH Sensor- Yordan Kostov, Ljubov Yotova and Stoyan Tzonkov Under-determination of Strontium-90 in Soils Containing Particles of Irradiated Uranium Oxide Fuel-Deborah H. Oughton, Brit Salbu, Tom L. Brand, J. Philip Day and Asker Aarkrog Titrations of Non-ionic Surfactants With Sodium Tetraphenyl- borate Using the Orion Surfactant Electrode-Robyn Dahl Gallegos Determination of Citric Acid and Oxalacetic Acid in Foods by Enzymic Flow Injection-Milagros Planta, Fernando Lazaro, Rosa Puchades and Angel Maquieira Relationship Between Geochemical Reference Material Characterization and the Development of New Methods for Geoanalysis-Jean S. Kane Determination of Derivatized Urea Herbicides in Water by Gas Chromatography With a Nitrogen-Phosphorus Detector- Steven Scott Decomposition of Biological Samples €or Inductively Coupled Plasma Atomic Emission Spectrometry Using an Open Focused Microwave Digestion System-Antoaneta Krushev- ska, Ramon M.Barnes and Chitra Amarasiriwaradena Simultaneous Determination of Catalysts Through a Single Catalytic Kinetic Run-Zhi-Cheng Gu, Zhong-Liang Zhu, Rong-Mei Chen, Bing-Liang Lu and Chuan-Qiang Han Speciation of Mercury in Natural Waters by Capillary Gas Chromatography With a Microwave-induced Plasma Emis- sion Detector Following Preconcentration Using a Dithiocar- bamate Resin Microcolumn Installed in a Closed Flow Injection System-HHkan Emteborg, Douglas C. Baxter and Wolfgang Frech Investigation and Elimination of Sodium Nitrate-Borate Interference on Manganese in Electrothermal Atomic Absorption Spectrometry-Yukihiro Koshino and Akira Narukawa Frequency Characteristics of an Electrode-separated Piezo- electric Crystal Sensor in Contact With a Liquid-Yao Shouzhou, Nie Lihua, Kang Qi, Lin Song and Shen Dazhong Determination of Phenol in Wastes and Water Using an Enzyme Sensor-L.Campanella, T. Beone, M. P. Sammartino and M. Tomassetti Simultaneous Determination of Anions and Divalent Cations Using Ion Chromatography and Eth ylenediamine te traace tic Acid Eluent-Christopher A. A. leGras Separation of Atomic Vapours by Sequential Metal Vapour Elution Analysis-Kiyohisa Ohta, Nobuhiro Yamanaka, Syn-Ya Inui, James D. Winefordner and Takayuki Mizuno Enzymic Assays of Organic Peroxides in Microemulsion Systems-Joseph Wang and A.Julio Reviejo Determination of Trace Amounts of Thallium and Tellurium in Nickel-base Alloys by Electrothermal Atomic Absorption Spectrometry-Suh- Jen Jane Tsai and Ching-Ching Jan Application of Poly(ani1ine) as an Ion Exchanger for the Separation of Palladium, Iridium, Platinum and Gold Prior to Their Determination by Neutron Activation Analysis-S. Gangadharan, Sanjiv Kumar and Rakesh Verma Spectrophotometric Determination of Lipohydroperoxides and Organic Hydroperoxides by Use of the Triiodide- Hexadecylpyridinium Chloride Micellar System-Dolores Pkrez-Bendito, Soledad Rubio and Ma Loreto Lunar Solid-phase Spectrophotometric Determination of Niobium in Rocks After Coprecipitation With Iron Quinolin-8-olate- Isoshi Nukatsuka, Toshihide Munakata, Kunio Ohzeki and Ryoei Ishida Modification of an Ultraviolet Spectrophotometric Method for the Determination of Trace Amounts of Phenols With Iodine Monobromide-Peixun Zhang and David Littlejohn Inverted Poly(viny1 chloride)-Liquid Membrane Ion-selective Electrodes for High-speed Batch Injection Potentiometric Analysis-Dermot Diamond, Joseph Wang, Qiang Chen and Jianmin LuEIRELEC 1993 Electrochemistry to the year 2000 September 11-15 Adare, Co.Limerick, Ireland Scientific Programme An international conference dealing with recent advances in electrochemical methodology, technology and sensors will be held at the Dun Raven Arms Hotel, Adare, Co. Limerick, Ireland. The programme will consist of plenary, invited and contributed oral papers and posters, and will be organized to allow for maximum discussion of papers.Plenary lectures will be given by: Professor A. Bard (USA) Professor J.O.M. Bockris (USA) Professor J. Wang (USA) A strong programme of invited and contributed lectures is currently being organized. Location Adare is a small, picturesque, historical village located just a short drive from Shannon International Airport (approx. 35 min). The village has been chosen because of the large range of activities it can provide, both cultural and sporting, and ample opportunity will be given to savour the local environment. The conference will be based in the "Olde Worlde" atmosphere of the Dun Raven Arms Hotel; a large range of accommodation is available within and close to Adare, ranging from the world renowned Adare Manor to pleasant bed and breakfast type lodgings. An option has been taken on several family holiday cottages within the town and these will be available to those delegates wishing to be accompanied by their families. Publication We have planned to publish a Special Issue of The Analyst based on the papers and posters that will be presented at this conference, and authors of invited and contributed papers will be encouraged to submit their papers to Professor M.R. Smyth at the address given below before, or at, the meeting. Those wishing to submit abstracts (1 page A4) or to obtain further details of the meeting should contact Professor Sm yth. The second circular for this meeting will be available in April 1993 and will contain full details of registration fees, accommodation, etc. Contact Address : Professor M.R. Smyth, School of Chemical Sciences, Dublin City University, Dublin 9, Ireland. Tel: +353-1-7045308; Fax: +353-1-7045503

ISSN:0003-2654    

DOI:10.1039/AN993180095N

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

ANALYST, JULY 1993, VOL. 118 Supercritical Fluid Chromatography With Electron-capture for the Determination of Agrochemicals Robert Moulder,* Keith D. Bartlet and Anthony A. Clifford School of Chemistry, University of Leeds, Leeds, UK LS2 9JT 737 Detection The scope for supercritical fluid chromatography with electron-capture detection of several test agrochemicals was investigated using a carbon dioxide mobile phase. Operation with packed capillaries was found to be preferable to conventional (large inside diameter) packed columns. The detector employed was found to be suitable for the detection of the high-melting point fungicides captan and captafol. Keywords: Supercritical fluid chromatography; electron-capture detection; agrochemicals; packed capillary column; high-melting point analyte One of the strengths of supercritical fluid chromatography (SFC) is its compatibility with a wide range of detectors in use with both liquid chromatography (LC) and gas chromato- graphy (GC).1-2 Amongst these is the electron-capture detec- tor (ECD); this has been long recognized in GC as an extremely sensitive means of identification of organic com- pounds con- taining heteroatoms,3~4 especially halogens. Previous studies have demonstrated a promising potential for the ECD as a post-SFC detector.'*2,s--7 Linear dynamic ranges up to four orders of magnitude with low- and sub-picogram detection limits have been reported for halogenated com- pounds.6 Failure to detect the high-melting point fungicides captan and captafol has been attributed to their insufficient volatility in the detector cavity.6 In this study, an ECD was used as an SFC detector for the determination of a variety of agrochemicals, including captan and captafol, using conventional packed columns, packed capillary columns and open-tubular columns.Experimental In all instances SFC was performed with the column in a Varian 3700 gas chromatograph and connected to a Varian h3Ni constant-current ECD8 operated at 300 "C. Nitrogen was passed through an oxygen trap and used as the detector make-up gas. Packed Column SFC Initial work using a 100 x 4.6 mm i.d. packed column ( 5 pm silica, LiChrosorb Si-60) was performed using a Gilson Model 303 reciprocating pump to deliver SFC-grade liquid CO2 (Air Products, Crewe, Cheshire, UK) at flow rates up to 2 cm3 min- I .The mobile phase was cooled by a refrigeration unit (Techne, Princeton, NJ, USA) to -8°C prior to pumping. A Rheodyne Model 7125 valve fitted with a 5 mm3 sample loop and maintained at 40°C was used for injection. The column eluate was split bctween an ultraviolet (UV) detector (Spectroflow 773) and the ECD with a splitting ratio of 200: 1. The flow of C 0 2 was directed through a pulse damper (Gilson Model 802C) prior to the injector. Lengths of 1/16 in stainless-steel tubing, 2.75 m X 0.762 mm i.d. and 20 m x 0.152 mm i.d., were also incorporated prior to the injector and post-UV detector, respectively, in order to effect further pulse damping. * Present address: Department of Analytical Chemistry, University of Uppsala, Sweden. To whom correspondence should be addressed.Packed Capillary and Open-tubular Column SFC Packed capillary and open-tubular column SFC were per- formed using a Carlo Erba 300 Series SFC pump (Fisons, Crawley, Sussex, UK). This was cooled by a Haake D8 refrigeration unit (Fisons) and controlled via an Innotech Systems computer (ITC-286). Injections were- initially per- formed with the Rheodyne valve (as above) fitted with a 0.17 mm3 loop of 50 pm i.d. fused-silica tubing. This was later changed in favour of the Valco CI4W injection valve (VICI, Houston, TX, USA) fitted with a 0.2 mm3 sample loop and pneumatics of a Carlo Erba 3000 Series SFC instrument. The injector was air driven and the solenoids operated from a 24 V power supply (Farnell, Wetherby, Yorkshire, UK). Lengths of 200 pm i.d.fused-silica tubing were slurry packed with 5 pm cyanopropyl-bonded silica (Spherisorb, Phase Separations, Clwyd, UK) from a 100 x 4.6mmi.d. stainless-steel reservoir. The ends of the columns were fitted with graphitized Vespel ferrules (SGE, Milton Keynes, Buckinghamshire, UK) into 1/16 in Valco low dead volume stainless-steel unions with the dead volume made up with poly(tetrafluoroethy1ene) (PTFE) spacers, and the packing was retained by 2 pm stainless-steel micro-screens (Phase Separations). The columns were connected to the injector by a 30 cm length of 75 pm i.d. deactivated fused-silica tubing. A 50 pm i.d. frit restrictor (Dionex, Camberley, Surrey, UK) was used to connect the column outlet to the ECD and trimmed to give the desired flow rate.A 10 m X 50 pm i.d. 30% biphenyl-substituted methylpoly- siloxane (0.25 ym film) open-tubular column (Dionex) was also used in this study. To decrease recorder noise, a 4700 yF capacitor was connected across the input of the chart recorder, thus increasing the time constant. Samples Solutions of heteroatom-containing agrochemicals were pre- pared in GC-grade hexane at concentrations ranging from 10 ng cm-3 to 50 yg cm-3. The following agrochemicals were studied: cypermethrin, tetrachlorvinphos, chlorthiamid, di- chlobenil, captan, captafol, linuron, diuron, p , ~ ' - D D T , -DDE and -DDD, o,p'-DDT, -DDE and -DDD, aldrin and lindane. Results Conventional Packed Column SFC-ECD Whilst operating both the packed and capillary systems, the use of a frit as opposed to a linear restrictor for the eluent split to the ECD was found to be essential.It was assumed that738 ANALYST, JULY 1993, VOL. 118 the rapid depressurization from the restrictor outlet achieved by the former more effectively 'sprayed' the solute into the detector. Optimum make-up gas flow rates and restrictor positioning were investigated. The conventional packed column system suffered greatly from baseline instability and poor day-to-day reproducibility. Sensitivities of at least a factor of 30 less than expected with conventional GC-ECD were observed when studying a series of test compounds, namely aldrin, DDT, DDE, DDD and a mixture of four geometric isomers of the pyrethroid cypermethrin. Fig. 1 is representative of the better results obtained, showing the separation of four geometric isomers of cypermethrin; detec- tion of 250 pg at a signal-to-noise ratio (S/N) marginally greater than 3.Examination of the baseline of this chromato- gram reveals a sawtooth-like effect, which is probably an effect of the pump pulses. Detection limits (DLs) of 20-40 pg (S/N = 3) were indicated for DDT, DDD and DDE isomers. Similarly, a DL near 10 pg was displayed for aldrin. These compounds are amenable to GC analysis but were chosen as simple test compounds for the compatibility of the detector with SFC. In conclusion, the main limitation of the conven- tional packed column system was a general baseline instabil- ity. With this borne in mind, it was hoped that the implemen- tation of a pulseless syringe pump would give better stability.Furthermore, it was expected that the sharper peaks asso- ciated with capillary SFC would further improve the detection capabilities. Packed Capillary and Open-tubular Column SFC-ECD The packed capillary SFC system did indeed show a greater improvement in baseline stability. In fact, for S/N = 3, DLs for DDT, DDE and DDE isomers were observed to be in the range 3-4 pg (Fig. 2). The detection system was, however, subject to long-term drift and although the detector body was well lagged with glass-wool, changes in the baseline were observed in the course of a day. Among the compounds selected for this study were captafol and captan (Fig. 3). Successful detection of levels down to 100 and 500 pg (S/N = 8), respectively, was observed. Chang and Taylor6 have previously reported a failure to detect captan and captafol using SFC-ECD.The Varian 63Ni ECD used in this study features a cell volume of 0.3 cm3,8 which compares with an effective volume of 1.1 cm3 (actual volume 2.1 cm3) of the Hewlett-Packard (HP) detector as used by Chang and Taylor.6 Adopting their argument of insufficient solute volatilization for these compounds in the HP detector, the 0 4 8 12 16 u 0 4 8 1 2 Time/m in Fig. 1 Packed column SFC-ECD separation of four geometric isomers of cypcrmethrin. Column: 100 x 4.6 mm i.d. LiChrosorb Si-60,s pm silica. Mobile phase: C 0 2 at 37.0 MPa (2 cm3 min-1, split at 200 : 1 to detector), 100 "C. Make-up gas: N2, 16 cm3 min-1. (a) and ( h ) 1.25 ng and 250 pg per component, respectively detection of these compounds may be attributed to superior volatilization in the smaller detector cavity; in our work the detector temperature was lower than that used in ref.6. Other agrochemicals included in this study were tetrachlor- vinphos, diuron, linuron, chlorthiamid and dichlobenil. Their elution and detectability were also checked using open- tubular columns (Fig. 4), but without optimization of separa- tion. The order of responses was as expected from the heteroatom content.4 These ranged from DLs of around 50 pg for tetrachlorvinphos and dichlobenil up to about 500 pg for diuron. In previous studies,lJj baseline rise during pressure pro- gramming was overcome by using higher make-up gas flow rates than those providing optimum sensitivity. When using the Varian ECD with nitrogen make-up gas it was found to be very difficult to maintain baseline stability during program- ming.This may also be attributed to the smaller volume of the detector cell. The use of a 1 : 1 split of packed capillary column effluent was seen to lead to increased baseline stability to pressure change. Optimization of the splitting ratio is expec- ted to show a potential improvement in this detection system. In the present study maximum detector response occurred with a make-up gas flow rate of about 15 cm3 min-1. The manufacturer's specified DL for lindane with this design of the Varian ECD in the GC mode is CO.1 pg (S/N = 2) with a linear range of >lo4 and a dynamic range of >105 with nitrogen make-up gas.* For SFC, DLs only down to 2.5 pg of lindane and reduced linear range and dynamic ranges of 103 and 104, respectively, were observed (Fig.5 ) . Standard deviations of approximately 8% peak height were observed for repeated injections. Although less sensitive than nitrogen, argon moderated with 5-10% of methane has the optimum carrier gas properties for ECDs for GC4 and, because of the noise level associated with the former, offers similar DLs. The I 2 3 0 2 4 6 8 1 0 1 2 1 4 Ti me/mi n Fig. 2 Packed capillary SFC-ECD o f y , p ' isomers of DDT (l), DDE (2) and DDD (3); 80,80 and 160 pgon-column, respectively. Column: 420 x 0.2 mm i.d., 5 pm cyanopropyl-bonded silica. Mobile phase: C 0 2 at 27.0 MPA and 100 "C '0 2 0 5 10 15 Time/mi n Fig. 3 Packed capillary SFC-ECD of captan (1) and captafol(2); 1.0 and 0.8 ng on-column, respectively.Column: 420 x 0.2 mm i.d.. S pm cyanopropyl-bonded silica. Mobile phase: C 0 2 at 100 "C and 37.0 MPaANALYST, JULY 1993, VOL. 118 739 Linuron CI Diuron Cl Chlorthiamid qSNH2 “‘0‘‘ Fig. 4 Open-tubular chlorthiamid ( 3 ) ; 1.6, mated). Column: 10 methylpolysiloxane (0. 80 “C 1 2 0 2 4 6 8 1 0 1 2 1 4 Ti me/m in SFC-ECD of linuron ( l ) , diuron (2) and 3.2 and 0.3 ng on-column, respectively (esti- m X 50 pm i.d. 30% biphenyl-substituted 25 pm). Mobilc phase: COz at 20.0 MPa and 4.0 r-- 1 Y 2.2 1 -I I I I 9‘ I I I I , 1.0 - 0 1.0 2.0 3.0 4.0 5.0 Log(amount on column/pg) Fig. 5 lindane. Column and conditions as in Fig. 3 Plot of log(peak height) versus log(amount on-column) for use of argon-methane (as used by Chang and Taylor,b as above) with the present system could conceivably offer further advantages over the nitrogen used here, including baseline stability whilst programming.Conclusions The use of ECD for trace analysis by SFC shows great potential. However, it would appear that a detector with optimized cell volume and geometry is required for sensitive and predictable performance. The lower volumetric flow rates associated with packed capillary and open-tubular capillary columns permit the use of pulseless syringe pumps and reduce the extent of ECD interference when compared with conven- tional-bore packed columns. We thank the Science and Engineering Research Council for financial support through a grant to R. M. References Richter, B . E., Bornhop, D. J., Swanson, J. T., Wangsgaard. J . G., and Andersen, M. R.. J . Chromatogr. Sci., 1989,27,303. Analytical Supercritical Fluid Chromatography and Extraction, eds. Lee, M. L., and Markides, K . E., Chromatography Conferences, Provo, UT, 1990. Detectors for Capillary chromatography, eds. Hill, H. H . , and McMinn, D. G., Wilcy, New York, 1902. Analysis of Pesticide Residues, ed. Moyc, H. A., Wiley-Inter- science, New York, 1981. Kennedy, S . , and Wall, R. J . , LC.GC, 1988, 6, 930. Chang, H.-C. K., and Taylor, L. T., J. Chromatogr. Sci., 1990, 28, 29. Munder, A., Christensen, R. G . , and Wise, S. A., J. Micro- column Sep., 1991, 3, 127. Varian Series 3700 Gas Chromatograph Operation and Main- tenance Manual, Publication No. 85-001139-00, Varian, Palo Alto. CA, 1977. Paper 310021 1 J Received January 13, 1993 Accepted March 19, 1993

ISSN:0003-2654    

DOI:10.1039/AN9931800737

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

ANALYST, JULY 1993, VOL. 118 74 1 Supercritical Fluid Extraction and Chromatography-Mass Spectrometry of Flame Retardants From Polyurethane Foams Graham A. MacKay Laboratory of the Government Chemist (LGC), Queens Road, Teddington, Middlesex, UK TWI I OLY Roger M. Smith Department of Chemistry, Loughborough University of Technology, Loughborough, Leicestershire, UK LEI I 3TU Four chlorinated organophosphate flame retardants present in polyurethane foams were analysed by supercritical fluid chromatography with flame-ionization detection and mass spectrometry. In addition, their amenability to gas chromatography was investigated. Real samples were analysed by using these techniques after on-line extraction with supercritical carbon dioxide. On-line quantitative extraction of the flame retardants from the polyurethane foams was investigated by using an external calibration.Keywords: Flame retardant; polyurethane foam; supercritical fluid chromatography; supercritical fluid extraction; mass spectrometry Flame retardants are incorporated in polyurethane foam mattresses to prevent rapid combustion. The most widely used retardants are chlorinated organophosphates, which are often employed in conjunction with more involatile retardants such as melamine.1 The organophosphates are viscous liquids that are almost totally immiscible with water and which breakdown at temperatures above 200 "C.2 Because of their instability at high temperatures, their extraction and chromatography must be performed at temperatures below 200 "C. The temperature required for their elution by gas chromatography (GC) often also causes thermal decomposition.Indeed, when analysed by gas chromatography-mass spectrometry (GC-MS) it was found that the two retardants with the highest relative molecular mass (Thermolin 101 and Amgard V6) did not elute at all. Their total immiscibility with water and lack of a suitable chromophore make reversed-phase liquid chromato- graphy (LC) difficult. It was found at the Laboratory of the Government Chemist (LGC) that selectivity was difficult to achieve in normal-phase LC as all the flame retardants tended to elute with the mobile phase front, although LC tests have previously been developed for the analysis of the solid flame retardant melamine. 1 The present study has examined the use of supercritical fluid extraction (SFE) and supercritical fluid chromatography (SFC) as a non-destructive test for all the flame retardant components of a foam.Because assays can be carried out under mild conditions, SFC has been proposed as the ideal method for the analysis of thermally labile compounds.3 Because of the temperatures that are commonly employed for carrying out SFC, elution of all the compounds was achieved without any signs of breakdown. Previously, SFE and SFC have been successfully performed on-line for the quantitative analysis of a number of other additives from polymers4-5 and both SFC-Fourier transform infrared spectrometry6 and SFC-mass spectrometry (SFC-MS)73X have been used for the identification of the components. The four flame retardants employed in this study are all chlorinated organophosphates and in common use as additives in foam mattresses.They are normally assayed by their retardant activity in a flame test.9 Experimental The mobile phase was carbon dioxide (SFC grade, Air Products). The standards were obtained from Albright & Wilson. Samples were from the Consumer Hazards sub- division, LGC. Supercritical fluid chromatography with flame-ionization detection (SFC-FID) and SFC-MS were performed on a Lee Scientific Series 600 chromatograph equipped with a 10 m X SO pm i.d., 0.25 pm film thickness, 30% biphenyl polysiloxane column from Lee Scientific, connected to a frit restrictor held at 350 "C. On-line SFE-SFC was performed using a 0.5 ml extraction cell incorporated in the Lee Scientific system.The extract was trapped cryogenically and concentrated at the top of the analytical column prior to chromatography. A Kratos MS50 double-focusing mass spectrometer fitted with an electron impact (EI) source set at 350 "C was used for SFC-MS. The scanning range was between mlz 100 and 600. The SFC column was connected to the mass spectrometer with a length of SO pm i.d. capillary tubing (enclosed in stainless- steel tubing) interposed between the column and the frit.8 Gas chromatography-MS was performed on a Finnigan 4500 quadrupole mass spectrometer fitted with a S:95 phcnyl-dimethyl (substituted) polysiloxane column, 25 m X 0.25 mm i.d., 0.25 pm film thickness, from Chrompack. Both spectrometers were interfaced to a Finnigan data system. Results and Discussion Supercritical Fluid Chromatography Four common flame retardants, Amgard TCEP, Amgard TMCP, Thermolin 101 and Amgard V6 (Fig.l), were studied. They were made up into a single solution in toluene and examined using SFC-FID. The compounds were eluted with no sign of breakdown (Fig. 2). Although, in capillary SFC, compounds are usually eluted in the order of ascending relative molecular mass, Amgard TMCP, which has a higher relative molecular mass than Amgard TCEP, was eluted earlier. This effect was reflected in the relative ease of extraction of the two compounds. At low pressures [lo0 atm (10.13 MPa)] Amgard TMCP was extracted with greater ease than Amgard TCEP. This was supported by further work, which showed that at 80 atm (8.11 MPa) Amgard TMCP was extracted slowly whereas Amgard TCEP was not extracted at all.Apparently the solubility of the retardant in the super- critical fluid is governing the order of elution in the chromato- graphy and the lower relative molecular mass compound is being retained.742 A - a - h~ -- I I I ANALYST, JULY 1993, VOL. 118 Amgard TMCP I (CI- CHZ-CH -0)3P=O CH3 Amgard TCEP (CI-CH2CHz- 0- )3P=O Thermolin 101 CI - CH2CH2 - 0 O-CH2CH2-CI CI-CH2CH2-0 ‘0- CH2CH2-CI >I-,- CH2-CH2- 0 - Amgard V6 O-CH2CH2-CI ;HZ-cI / CI - CH2CH2- 0 >:-O-CH2- C- CH2-0- P, CI- CH2CH2- 0’ I CH2-CI Fig. 1 Structures of the four flame retardants employed in this work 16 k II I m Amgard TMCPl 2 AmgardV6 (T) r; Amgard TCEP Thermolin, 101 I I I I I 1 0 10 20 30 Ti me/m in Fig. 2 SFC trace of the four flame retardants.Condition: column, 30% biphenyl polysiloxane; oven temperature, 100 “C; pressure programme, 100 atm (10.13 MPa) for S min then increased from 100 to 300 atm (10.13-30.40 MPa) at 5 atm (0.51 MPa) min-1; detection, FID at 350 “C On-line Qualitative Extraction In order to analyse polyurethane foams for the presence of the fire retardants, they would normally have to be extracted with a solvent and the retardants isolated and individually identi- fied. If there is a mixture of retardants in the foam, identification of each component will be difficult because of the lack of selectivity of conventional forms of chromato- graphy for these compounds. On-line SFE-SFC was examined as a method of resolving this problem. Three different foams, which contain among them the four most common flame retardants, were analysed by SFE-SFC.These were: ‘Safegard’, which contained Amgard TMCP and Amgard V6; ‘HG35S’, which contained Thermolin 101; and ‘FHR30H’ which contained Amgard TCEP. Usually the flame retardants are present in the foams at levels of 1-3% and, therefore, only a small amount of the foam was required; about 0.2 mg was sufficient to obtain a representative chromatogram. In addition, because of their relatively easy elution from the SFC column, their solubility in carbon dioxide was expected to be sufficiently high to permit easy extraction. Each analysis consisted of sub-sampling a small amount of foam and placing the sub-sample in a 0.5 ml extraction cell. Extraction was then performed for 5 min at 300 atm (30.40 MPa) and 60 “C.The carbon dioxide depressurizes to concentrate the sample at the top of the capillary column. The sample is then chromatographed [Fig. 3(a)-(c)], using the same conditions as in Fig. 2. Q, . m Q m cc 16 0 Thermolin 101 1 . I l6 I (D c9 7 - hl Amgard TCEP Supercritical fluid extraction occurs mainly at the surface and, therefore, the extraction matrix either needs to be permeable in order to allow transport of the additives or needs to have a high surface area.’” It appears that the polyurethane foams possess both properties and as a result enabled easy and representative extraction of the flame retardants to be carried out. When compared with direct injection, however, the peak shapes were found to have deteriorated as a result of the analyte being introduced by decompression at the start of the column. SFC-MS of the Flame Retardants In order to confirm the identity of the retardants, on-line mass spectra of the compounds were obtained (Fig.4). The programme employed for SFC-MS ensured that the pressure was kept to a maximum of 250 atm (25.33 MPa). This enabled a better sensitivity to be obtained than with the programme used for SFC-FID as a higher SFC pressure would reduce the vacuum in the mass spectrometer.8 The source temperature was held at 350 “C in order to minimize the formation of carbon dioxide clusters.8 The peaks showed no deterioration in shape from the SFC-FID separation. This shows that the interface was sufficiently efficient to transport the analyte into the source. The spectra [Fig.5(a)-(d)] were similar to those obtained by probe analysis of standards on the same instrument. However, in each instance there were small differences in the relative abundances of some of the ions. In its development, the SFC-MS system had shown a tendency for a suppression of the higher relative molecular mass ions including the molecular ion when compared with the lighter ions.8 This distortion was thought to be because of the higher source pressures encountered with the SFC instrument when compared with the pressures found in either GC-MS or probe-MS. This effect has been found previously in SFC-MS by Cousin and Arpino.”ANALYST, JULY 1993, VOL. 118 13:~’ 187 205 161 743 249 329 39 1 223 267 SFE-SFC-MS of the Flame Retardants A combination of SFE and SFC-MS led to the possibility of rapid identification of the contents of a foam by SFE-SFC- MS.The extraction conditions employed in Fig. 3, for the analysis of the three foams by SFE-SFC, were combined with the chromatographic conditions employed for SFC-MS in Fig. 4. The peak shapes obtained were of approximately the same efficiency as those observed using SFE-SFC (Fig. 3) but I 200 250 300 350 400 450 500 mlz I I I I I I I I I I 13:50 17:17 20:45 24:12 27:40 31:07 34:35 Time/min : s Fig. 4 Reconstructed ion current of SFC-MS of four flame retar- dants. Conditions: isobaric at 100 atm (10.13 MPa) for 5 min followed by a pressure programme to 250 atm (25.33 MPa) at S atm (0.51 MPa) min-I with the pressurc remaining isobaric at 250 atm (25.33 MPa) for 5 min; isothermal at 80°C for 25 min followed by a negative temperature programme, 50°C at 5 “C min-l with the temperature remaining at SO “C for 9 min 100.0 50.0 8 E o 9 100.0 - > w .- + .- .- w - 0) CT 50.0 0 I99 125 I 157 100 120 140 showed a lower efficiency than the peak shapes of the solvent-injected standards obtained by SFC-MS (Fig.4). However, the spectra obtained were still representative of the standard flame retardants. Even Amgard V6, which elutes at the highest SFC pressure (at this point the mass spectrometer is at its least sensitive), gave a spectrum that was compatible with the probe and SFC standards. Fig. 6 shows the SFE-SFC-MS profile of ‘Safegard’; the presence of Amgard TMCP and Amgard V6 in the extract is evident. Quantitative SFE-SFC Solvent extracts of the foams, in toluene, were examined by SFC and were compared with the standard solution to give the concentrations of the retardants (Table 1).In order to obtain the best reproducibility of injection volume, the smallest injection loop (60 nl) was used. The injection timing was set at 10 s, which would be sufficient for the loop to be fully flushed three times. It had been found that partial loop injection using a split time was not very reproducible, giving a reproducibility of, at best, 8%. The reproducibility of the injector system used here was 3.8%. This method gave calibration graphs (Fig. 7 ) with a good correlation. This study was then extended to on-line extraction-chro- matography, which has been used by several workers for the quantitative analysis of polymer additives.12713 However, in each of these instances packed chromatography was employed and the calibration was performed by adding a standard ‘spike’ to the polymer in the extraction vessel. This approach is more difficult with capillary columns as the volumes and concentrations that would need to be employed are considerably less. Other workers have even suggested that on-line quantitative analysis is not feasible as the extraction times are too long14 and erratic results can be obtained. 100.0 50.0 0 160 180 200 220 240 260 280 100 205 50.0 107 125 21 3 150 200 250 300 350 400 325 (4 223 I 107 I1 !5 205 136 161 1 I 359 i I 1 100 120 140 160 180 200 220 240 :OO 150 200 250 300 350 400 450 500 mlz Mass spectra from SFC scparation of retardants.(a) Amgard TMCP, ( b ) Amgard TCEP, (c) Thermolin 101 and (d) Amgard V6 Fig. 5ANALYST, JULY 1993, VOL. 118 744 100.0 s 2 - w C 3 0 c .4! 50 -0 4- 2 4- v) c 0 a, [r 0 31 4 Amgard TMCP , AmgardV6 100 200 300 400 500 600 mlz I I I I I I I 0 6.15 12:30 18:45 25:OO 31:15 3 7 : 3 0 Timelmin : s Fig. 6 SFE-SFC-MS of 'Safegard' showing the presence of both Amgard TMCP and Amgard V6. Chromatographic conditions as in Fig. 5 . Extraction conditions as in Fig. 4 Table 1 Levels of flame retardants in foams as found by using solvent extraction and SFC determination Foam Flame retardant Level (%)* 'Safegard' Amgard TMCP 1.4 k 0.1 'Safegard' Amgard V6 1.4 k 0.2 'HG35S' Thermolin 101 2.3 k 0.2 FHR30H' Amgard TCEP 0.9 k 0.1 * -t standard deviation (n = 4). 40 1 3 0 5 10 15 20 25 Mass of retardant/l0-7 g Fig.7 Calibration graphs for the flame retardants in SFE-SFC separation. Chromatographic conditions as in Fig. 2. A, Amgard TCEP; B. Amgard TMCP; C. Thermolin 101; and D, Amgard V6 A small weighed amount of each foam was placed in an extraction cell and extracted. The extract was trapped cryogenically at the top of the capillary column. After the extraction was complete, chromatography was performed on the extract. The peak area of the FID response was measured and compared with the calibration graphs obtained by injection. From the mass of retardant extracted from the foam under different conditions, the concentration could be calcu- lated (Tables 2-5). Extraction of Amgard TMCP From 'Safegard' For the extraction of Amgard TMCP from 'Safegard' (Table 2), a Concentration of the retardant that was close to the expected level of 1.4% was obtained after extraction for 10 Table 2 Quantitative SFE-SFC of Amgard TMCP from 'Safcgard' under different conditions Mass of foamlg Mass of retardant/g Yield (YO) 300 atm (30.40 MPa); 60 "C; 10 min- 0.0002 1 2.9 x 10-6 1.4 0.00028 4.8 x 1.7 0.00017 2.8 x 10-6 1.6 0.00029 4.4 x 10-6 1.5 0.00022 7.1 x 10-7 0.3 0.00026 6.7 x 10-7 0.3 0.000 16 1.7 x 10-7 0.1 0.00028 9.1 x 10-7 0.3 0.0001 7 1.1 x 10-6 0.6 0.00051 1.8 x 10-6 0.3 200 atm (20.27 MPa); 60 "C; 10 min- 100 atm (10.13 MPa); 60 "C; 10 min- 100 atm (10.13 MPa); 60 "C; 25 min- Table 3 Quantitative SFE-SFC of Amgard V6 from 'Safegard' under different conditions Mass of foam/g Mass of retardant/g Yield (%) 300 atm (30.40 MPa); 60 "C; 10 min- 0,00032 3.2 x 10-6 1 .0 0.00021 1.4 x 10-6 0.7 0.00029 4.3 x 10-6 1.5 0.00045 4.8 x 10-6 1.1 200 atm (20.27 MPa); 60 "C; 10 min- ~ Table 4 Quantitative SFE-SFC of Amgard TCEP from 'FHR30H' undcr different conditions Mass of foam/g Mass of retardant/g Yield (YO) 300 atm (30.40 MPa); 60 "C; 10 min- 0.00034 3.2 x 10-6 0.9 O.OO048 3.8 x 10-6 0.8 0.00032 2.5 x 10-6 0.8 0.0002s 1.2 x 10-6 0.5 0.00024 1.3 x 10-6 0.5 0.000 15 1.4 x 10-6 0.9 0.00024 1.7 x 10-7 0.1 0.00014 1.5 x 10-7 0.1 0.00017 1.8 x 10-7 0.1 0.0001 7 4.8 x 10-7 0.3 0.00033 5.9 x 10-7 0.2 0.00017 3.9 x 10-7 0.2 200 atm (20.27 MPa); 60 "C; 10 min- 100 atm (10.13 MPa); 60 "C; 10 min- 100 atm (10.13 MPa); 60 "C; 25 min- ~~~ Table 5 Quantitative SFE-SFC of Thermolin 101 from 'HG35S' under different conditions Mass of foam/g 300 atm (30.40 MPa); 60 "C; 0.00026 O.OO026 0.00023 0.00019 0.0004 1 0.00030 200 atm (20.27 MPa); 60 "C; Mass of retardantlg 0 min- 7 .8 ~ 7.4 x 10-6 6.5 x 4.7 x 10-6 8.5 x lo-" 0 min- 1.1 x 10-5 Yield (YO) 3.0 2.8 2.8 2.5 2.7 2.8 min at pressures of 200 and 300 atm (20.27 and 30.40 MPa). At these pressures and with the small amount of foam extracted the process was rapid. At lower pressures the reduced solubility of the retardant in the extraction fluid gave a reduced yield. Alternatively, it is possible that the slow flow rate through the back-pressure restrictor could also be hindering rapid extraction.ANALYST. JULY 1993, VOL. 118 745 Extraction of Amgard V6 From ‘Safegard’ The yields of Amgard V6 from ‘Safegard’, where it is present at a level of 1.470, were relatively low and erratic (Table 3) when compared with the extraction of Amgard TMCP under the same conditions.No extraction occurred at 100 atm (10.13 MPa). This could be explained by the low solubility of Amgard V6 in the supercritical fluid, However, there may be other reasons why Amgard V6 has a slow extraction rate even at the higher pressures. The transport of the retardant in the polyurethane foam may also be slower because of the bulky nature of Amgard V6. If this was true, then the extraction, even at elevated pressures, and hence elevated solvating power, would be expected to be incomplete. This is shown by the small difference in the extraction performance of carbon dioxide at 200 and 300 atm (20.27 and 30.40 MPa).It is most likely, however, that a combination of low solubility in carbon dioxide and slow transport in the foam is responsible for the poor extraction values. In order to achieve a more reliable value for the concentration of Amgard V6 in the foam, a longer extraction time would be needed. Conclusion Supercritical fluid extraction-SFC-MS can be used for the rapid qualitative analysis of flame retardants in polymers. This analysis would be difficult to perform by alternative methods. On-line quantitative analysis is possible because of the high surface area of the polyurethane foams and the reasonable solubility of the retardants in supercritical carbon dioxide, although there is reduced recovery for the less soluble retardants. Both the extraction and the chromatography of the flame retardants are more rapid for the two lighter retardants, TMCP and TCEP, because of the lack of steric bulk acting on the mass transport in the foam arid the higher solubility of these two retardants.Extraction of Amgard TCEP From ‘FHR30H’ In the extraction of Amgard TCEP from ‘FHR30H’, most of the retardant, present at a level of 0.9%, was recovered after extraction for 10 min at 300 atm (30.40 MPa) (Table 4). Approximately 50% was recovered at 200 atm (20.27 MPa) and very little at 100 atm (10.13 MPa). There was a slight increase in recovery when the extraction was carried out for 25 min. This clearly shows the effect of solubility on extraction. Even with small amounts of foam, extraction could be hindered by the poor solvating power of the fluid for a particular retardant.Extraction of Thermolin 101 From ‘HG35S’ At 300 atm (30.40 MPa) there was almost total extraction of Thermolin 101, present at a level of 2.3%, from ‘HG35S’ and, as with the other flame retardants, there was a slight decrease at 200 atm (20.27 MPa), probably because of the reduction in solubility of the retardant in the fluid. The extraction was also attempted at 100 atm (10.13 MPa) with little or no recovery. The extractions observed in theie examples appear very rapid when compared with other work on the extraction of polymers, when hours or days have been required to obtain plasticizers.1”lfJ This can be explained by the structure of the polyurethane foams, which consist of a matrix of fibres.The thickness of these fibres is approximately 30 pm, tapering to a negligible thickness at the edges. Previous work with poly- urethane foam sorbents17 has shown that the surface area is very large and the matrix is very thin; hence the transport of the extracts can be rapid,l0 particularly at pressures above 200 atm (20.27 MPa). The work performed in this study was supported by the Valid Analytical Measurement programme, which is funded by the Department of Trade and Industry, UK. I 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 References Cody, M. K . , and Patterson, I . D., Fire Mazer., 1992, 15, 1. Product Data Sheets, Albright & Wilson, Warley, West Midlands. Analytical Supercritical Fluid Chromatography and Extraction , eds. Lee, M. L., and Markides, K. E., Chromatography Conferences, Provo, UT, 1990, p. 277. Cotton, N. J., Bartle, K. D., Clifford, A. A., Ashraf, S . , Moulder, R., and Dowle, C. J., J. High Resolut. Chromatogr., 1991, 14, 164. Anton, K., Menes, R., and Widmer, H. M., Chromatographia, 1988, 26, 221. Raynor, M. W., Bartle, K. D., Davies, I. L., Williams, A., Clifford, A. A., Chalmers, J. M., and Cook, B. W., Anal. Chem., 1988, 60, 427. Arpino, P. J., Dilettato, D., Nguyen. K., and Bruchet, A.. J . High Resolut. Chromatogr., 1990, 13, 5. MacKay, G. A., and Reed, G. D., J. High Kesolut. Chroma- togr., 1991, 14, 537. BS 5852, Part 2: 1982, Fire Test For Furniture. British Standards Institute, Manchester. Bartle, K. D., Clifford, A. A., Hawthorne, S. B., Langenfeld, J. J.. Miller, D. J., and Robinson, R., J . Supercrit. Fluids, 1990, 27, 143. Cousin, J . , and Arpino, P. J., J. Chromatogr., 1987, 398, 12.5. Ryan, T. W., Yoklovich, S . G., Watkins, J. C., and Levy, E. J . , J. Chromatogr., 1990, 505, 273. Ashraf-Khorassani, M., and Levy, J. M., J. High Resolut. Chromatogr., 1990, 13, 742. Bartle, K. D., Boddington, T., Clifford, A. A., Cotton, N. J., and Dowle, C. J . , Anal. Chem., 1991, 63,2371. Hirata, Y., and Okamoto, Y., J. Microcolumn Sep., 1989,1,46. Kuppers, S . , Chromatographia, 1992, 33, 434. Hawthorne, S . B., Krieger, M. S . , and Miller, D. J., Anal. Chem., 1989, 61, 736. Paper 3100243H Received January 14, 1993 Accepted February 3, 1993

ISSN:0003-2654    

DOI:10.1039/AN9931800741

出版商:RSC    

年代:1993

数据来源: RSC

摘要:

ANALYST, JULY 1993, VOL. 118 747 Application of Supercritical Fluid Extraction in the Pharmaceutical Industry: Supercritical Fluid Extraction of Megestrol Acetate From a Tablet Matrix John R. Dean and John Lowdon Department of Chemical and Life Sciences, University of Northumbria at Newcastle, Ellison Building, Newcastle upon Tyne, UK NE I 8ST The factors that influence the extraction of megestrol acetate from a tablet formulation are discussed. A comparison of the Hewlett-Packard HP7680A and a Jasco supercritical fluid extraction (SFE) system is made. Under similar conditions the HP7680A provides a complete recovery of analyte whereas the Jasco system is prone t o analyte loss after depressurization. It is proposed that different SFE methods be compared using the number of cell volumes swept as the criterion of importance.A direct comparison of SFE with a United States Pharmacopeia (USP) monograph method for the analysis of megestrol acetate from tablet formulations has been investigated. Overall, the USP method provided more precise and accurate determinations for the determination of megestrol acetate from a tablet matrix. Keywords: Supercritical fluid extraction; pharmaceutical analysis; megestrol acetate; tablet matrix Hormones are produced by groups of cells (endrocrine glands) which regulate the various life functions in an organism. The steroid hormones form an important group of hormones of which there are five major classes: 1 progestogens, androgens, estrogens, glucocorticoids and mineralocorticoids. At present, both the number and the amounts of artificial steroid hormones used in therapy greatly exceed those of natural hormones used previously from purified animal extracts, as the strength and specificity of the synthetic hormones often exceed that shown by the naturally occurring analogues.' An important hormone involved in the female menstrual cycle is progesterone-1 It is secreted by the corpus luteum in thc ovary and prepares the lining of the uterus for the reception of the ovum and maintains the lining, preventing ovulation after fertilization.The primary usc of the proges- togens is in the treatment of menstrual irregularities and other gynaecological diseases to maintain endangered pregnancies owing to thcir ovulation inhibitory potency. One such synthetically active progesterone compound commonly avail- able as a prescription medicine in tablet formulation is megestrol acetate (3,20-dioxopregna-4,6-dien-17-yl acetate) (Fig.1). Steroid hormones are used in various dosage forms in therapy and are prepared as formulations in tablets, oily or aqueous suspension injectables, ointments and creams. 1 The most convenient means of extracting steroid hormones from tablets is to treat them with a solvent such that the resulting extract can be used directly in the assay method chosen, e.g., extractions with ethanol or methanol, and the test solution can be obtained directly by filtration or centrifugation of the mixture. However, where binding of the active to polar excipients occurs, e.g., corticosteroids with lactose, the extraction loses its effectiveness. In such instances, in order to reduce the adsorption losses and increase selectivity of the extraction, a two-phase extraction is often used: one of the solvents, e.g., water, dissolves the lactose, thus allowing complete extraction by the other solvent which is immiscible with water, e.g., chloroform or diethyl ether.The two-phase extraction is time consuming and often undissolved excipient gives rise to emulsions during the extraction step. In addition to the type and amount of active ingredient, the manner of preparation of the tablet also has to be considered as this can influence the extractability of the steroid. Supercritical fluid extraction (SFE) is a technique that exploits the properties of a substance in a fluid state at temperatures and pressures near the critical point.Of particular relevance to the solvating power of a supercritical fluid, usually carbon dioxide, are the following parameters:2 temperature, density, time of extraction, primary extraction fluid, the method of introduction and choice of modifiers, sample particle size and mode of sample accumulation. Carbon dioxide has so far been the most widely used supercritical fluid because of its low critical temperature (31.1 "C), modcrate critical pressure 17.38 x 106 Pa (73.8 bar)], and high purity at relatively low cost.*J However, the major limitation of carbon dioxide is its inability to extract polar analytes at typical working pressures [2.4 X 1074.8 X 107 Pa (350Ck7000 psi)]. The extraction of polar analytes requires the addition of modifiers (co-solvents) to the carbon dioxide.These co-solvents, e.g., methanol or acetonitrile, can be introduced via a second pump.4 The potential for SFE as a sample preparation technique to extract steroid compounds"." from tablet/excipient formula- tions selectively is currently of interest in the pharmaceutical industry. This paper evaluates the use of SFE to extract megestrol acetate from tablet formulations and suspensions. Initial work indicated that megcstrol acetate was a suitable steroid for investigation not only because of its solubility in supercritical carbon dioxide2 but also because of its solubility in methanol. The latter provided ease of quantification using utlraviolet-visible (UV/VIS) spectrophotometry . Finally, SFE is compared with an official United States Pharmacopeia (USP) method.Instrumentation Two SFE systems were used. The first was a Hewlett-Packard HP7680A computer driven system with total software control and the sccond a Jasco SFE system with dual reciprocating pumps allowing addition of modifier and carbon dioxide. The HP7680A SFE consists of a twin piston pump which allows liquid carbon dioxide (SFC Grade, Air Products, Sunderland, UK) to be pumped at flow rates between 1 and 4 ml min-1 and at prcssures up to 3.65 X lo7 Pa (365 bar). The sample vessel ( I ml capacity) is a stainless-steel tube with PEEK caps fitted with 10 pm frits at either end. The vessel is inserted into a sample well which is raised under computer control to form a high-pressure seal. Extraction can be performed in either static or dynamic mode.In the latter mode carbon dioxide is continuously flowing through the vessel whereas the static mode allows the sample to 'soak' in carbon dioxide. In practice a combination of static and dynamic extraction has748 0 vMe ANALYST, JULY 1993. VOL. 118 ~~~~ Table 1 Typical operating conditions for SFE Instrument Me Fig. 1 Structural formula of megestrol acetate been found to be the most effective to achieve maximum recovery.6 The system pressure is controlled by an electronic- ally actuated variable restrictor. The variable restrictor allows independent control over the flow and pressure of the system. On depressurization the extracted components are collected onto chromatographic support material while the carbon dioxide is vented to waste.In this study Hypcrsil ODS (30 pm) was employed for the collection of the extracted analyte. Finally, analytes are eluted from the support material by selecting an appropriate solvent, i. e . , methanol. The Jasco SFE system utilizes two reciprocating pumps, a master pump (Jasco 880-PU) fitted with a cooling jacket on the pump head to maintain the liquid state of the carbon dioxide and a second pump for the addition of organic modifier. The extraction cell (1.5 ml capacity) is manually wrenched into the thermostatic- ally controlled oven (Jasco 860-CO). Using the dynamic mode, fresh carbon dioxide is continuously swept through the sample cell prior to depressurization. In-line monitoring of the analyte is possible via a UVNIS spectrophotometer (Jasco UV979).Depressurization is achieved using an oscillating variable restrictor (back-pressure regulator, Jasco 880-81). The extracted analyte was collected in a spring-loaded boiling tube or trap into which was placed a few millilitres of solvent (methanol). This collection device was later modified owing to initial problems with anal yte collection. This involved extend- ing the collector into the collection tube by means of a short piece of plastic poly(viny1 chloride) (PVC) tubing over which was placed a small plastic PVC disc. The disc was positioned at the top of the plastic tubing to prevent loss of analyte as an aerosol and encourage condensation of the analyte within the collection tube. Typical operating conditions for both SFE instruments are shown in Table 1.Megestrol acetate standard was supplied by the Standards and Validation Department at Glaxo Manufacturing Services (Barnard Castle, Co. Durham, UK). This material has a certified purity of 99.5% m/m. Megestrol acetate tablets ('Megace') were supplied as 40 and 160 mg formulations by Bristol-Myers Oncology Division (Bristol-M yers Pharmaceut- icals, Langley, Slough, UK). Tablets are the only formulation in which megestrol acetate is currently available. The extracts were quantified at 288 nm using a Uvikon 860 spectrometer. A calibration plot was constructed by serial dilutions of a solution of megestrol acetate in methanol over an appropriate calibration range. Simple lincar regression was applied to the corresponding absorbance and concentration values and a line of best fit determined using a computer package (Statgraphics, Mercia Software, Birmingham, UK).Various support materials were assessed for their suitability as adsorbents, for megestrol acetate in methanol, prior to extraction from the sample vessel. These included: glass beads, 150-200 mesh, 250 GMX; Chromosorb W AW, 100-120 mesh; and molecular sieve, 100-120 mesh 5A, all supplied by Phase Separations (Clwyd, UK). Celite, 80-100 mesh, was supplied by BDH (Poole, Dorset, UK). USP Method for Megestrol Acetate Tablets7 Megestrol acetate tablets were assayed according to the following procedure. Five tablets of each formulation were Parameter HP7680A COX only Fluid delivery- Density/g ml-1 0.65 Pressurehar (kPa) 149 (14 900) Flow rate/ml min-1 2.0 Temperature/"C 55 Equilibration time/min 2.0 Extraction timdmin 5.0 Cell volume/ml 1.5 Cell volumes swept 9.4 Extruction- Depressurizution- Analyte collection ODS column Collectiordwash solvent MeOH * NA = not applicable to this system.Jasco C 0 2 + modifier (if required) 0.66 2.0 151 (15 100) 55 NA* 3.0 1 .0 8.4 Tube McOH individually weighed and placed into calibrated flasks (50 ml capacity for the 40 mg tablets and 200 ml capacity for the 160 mg tablets). To each flask was added 1 ml of water to disintegrate the tablets. This was followed by methanol added to 75% of the fill volume. The flasks were then shaken for 20 min, diluted to volume with methanol, shaken and finally fiItered through a 0.45 pm Acrodisc. Then, 3 ml of filtrate were diluted to 200 ml with methanol and the absorbance recorded in 1 cm cells against a methanol blank at 288 nm.The concentration of megestrol acetate in solution was determined by comparison with the absorbance obtained from a working curve produced using a standard solution of megestrol acetate. Results and Discussion Previous work from this group on steroids has indicated that the main factors that influence extraction are the density, temperature, time and the flow rate of carbon dioxide.6 Using an experimental design approach to investigate the effect of each of the variables and their associated interactions on the recovery of steroids the main influence on the extraction efficiency was determined to be the density of the supercritical carbon dioxide.h With this in mind, compromise extraction conditions, typical of those previously found to give a high recovery of analyte, were selected (Table 1) .6 Recovery of Analyte From Support Materials A 50 p1 aliquot of a standard solution of megestrol acetate (1.208 mg ml-1) in methanol was placed onto a series of support materials using a microsyringe. The solvent was allowed to evaporate to dryness in a current of warm air prior t6 SFE using the HP7680A system and the conditions outlined in Table 1.Care was taken to ensure sufficient time was allowed for the solvent to evaporate to prevent enhanced recovery of analyte due to modification of the supercritical carbon dioxide. Five support materials were chosen to assess the recovery of megestrol acetate (60.4 pg). The five support materials chosen were: a 1 cm glass tube (4 mm i.d.); glass beads (3 g), molecular sieve (0.4 g), Celite (0.2 g) and Chromosorb W AW (0.25 g).The amount of each support required was experimentally determined to be sufficient to adsorb the 50 p1 volume without being present in excess. The results of this recovery exercise are shown in Table 2. With the exception of the molecular sieve data the mean recovery from the other support materials, i . e . , 14 determinations, is 97.4% with a relative standard deviation (RSD) of 6.4%. This is evidence that supercritical carbon dioxide was able to desorbANALYST, JULY 1993, VOL. 118 749 the analyte residue from each of the support materials successfully with the exception of the molecular sieve. The nature of molecular sieves, i .e . , synthetic alkali metal alumi- nosilicates, with regular channels and pores within a lattice structure, provides ideal adsorption surfaces for both the carbon dioxide and analyte to be retained, and hence a longer extraction time may be required to allow the analyte to diffuse out of the matrix. The low recovery of megestrol acetate demonstrates the unsuitability of this support and further work was therefore unnecessary. Celite was selected for further studies. As outlined above, the variable with the maximum effect on the recovery of steroids was determined to be the density of supercritical carbon dioxide. Further investigations were undertaken in order to assess the recovery of megestrol acetate from the Celite support material. The density for extraction was altered by changing the pressure of the system while maintaining a constant temperature.Four densities were selected to investigate the influence of supercritical carbon dioxide density on the extraction of megestrol acetate. The densities selected were: 0.16; 0.43; 0.66; and 0.81 g ml-1. The effect of density on the extraction recovery of megestrol acetate is shown in Table 3. These data and all subscquent experimentation were obtained on the Jasco SFE system. Comparison of the recovery data at a carbon dioxide density of 0.66 g ml-1 allows a direct comparison of the two SFE instruments. It is clearly seen (Tables 2 and 3) that the recovery of megestrol acetate from Celite was substantially reduced using the Jasco system. Every attempt was made to compare extraction conditions between the systems directly but obviously because of equipment restraints (e.g., extrac- tion cell volumes differ) this was not entirely possible.However, as reported previously6 an important feature to consider in comparing data from laboratories and in this instance manufacturer's instrumentation is the number of cell volumes swept. The number of cell volumes swept can be determined using the following equation:h Table 2 Recovery of megestrol acetate from solid support matrices Number of RSD Support material determinations Recovery (%)* (%> Glass tube 5 90.6 (93.2,85.5,92.4, 3.5 92.4,89.5) Glass beads 3 103.4(100.6,105.6,104.0) 2.5 Molecular sieve 3 67.4 (67.5.71.8,62.8) 6.7 Celite 3 103.0(104.3, lOl.l,103.5) 1.6 Chromosorb W AW 3 97.0 (96.9,99.3,94.8) 2.3 * Mean (individual recoveries).Table 3 Effect of density on the recovery of megestrol acetate Number of RSD Density/g ml- 1 determinations Recovcry (%)* (Yo 1 0.16 4 0 0 0.43 4 68.5 (6S.4,67.4.70.0,71.0) 3.7 0.66 4 69.4(68.4,69.3.68.7,71.3) 1.9 * Mean (individual recoveries). Cell volumes swept = (flow rate of C 0 2 x time of extraction)/ volume of cell We have previously recommended that the number of cell volumes swept be at least 4.6 In this instance the number of cell volumes swept was determined to be 9.4 and 8.4 for the HP768OA and Jasco system, respectively. No recovery of megestrol acetate was obtained from the lowest density (below the critical pressure of carbon dioxide at 5.5 "C), thus demonstrating that megestrol acetate is not soluble in gaseous carbon dioxide.Increasing the density of supercritical carbon dioxide at 5.5 "C increases the recovery of megestrol acetate from the Celite support. Assay of Megestrol Acetate Tablets Using the USP Monograph7 Each of the tablet formulations (40 and 160 mg active ingredient) was assayed according to the USP monograph7 for megestrol acetate tablets. The method was adopted to assay content uniformity in the tablets using five tablets of each formulation. The results are shown in Table 4. The assay values are in good agreement with the claimed dosage. The mg per tablet values demonstrate greater variability than the mgg-1 values. This is expected because tablet masses are more difficult to control in the manufacturing process, whereas the mg g-1 values should remain constant if the tablet mix before pressing is homogeneous.Extraction From Tablet Matrix Using Supercritical Carbon Dioxide Analyte recovery from a tablet formulation depends not only on the extraction conditions used but also on physical properties, e.g., particle size, of the matrix. In addition to the physical properties, the extraction process from a tablet matrix involves several steps, including analyte diffusion and the overcoming of adsorption forces associated with the matrix. In order to aid the extraction process from a tablet formulation all tablets were ground to a powder form. The need for grinding was demonstrated by the poor recovery obtained using supercritical carbon dioxide when extracting directly from a tablet (3%).However, the process of grinding can itself lead in some instances to separation of analyte and excipients owing to particle size differences. A 160 mg tablet was first weighed, then ground to a powder. From this, six 20 mg fractions of the sample were removed and extracted over increasingly longer time periods at supercritical carbon dioxide conditions of 55 "C, 0.81 g ml-1 [2.47 x 107 Pa (3579psi)l and a flow rate of liquid carbon dioxide of 2 ml min-1. The results shown in Table 5 indicate that an extraction time of 20 min is required to achieve the maximum recovery of 70.4%. However, it must be assumed that loss of analyte occurs throughout the extraction procedure; this is probably due to loss of analyte from the collection device. Table 4 USP method for megestrol acetate tablets RSDt RSDi Tablet Tablet mass*/g Assay value*/per tablet (Yo 1 Assay value*/mg g-1 (Yo) Nominal 40 mg formulation 0.4036 (O.4O66,0.3972,0.407Oq 40.47 (40.78,39.84,40.63 ~ 0.90 100.28 (100.30, I00.30,99.83, 0.41 0.4OS0, 0.4020) 40.52,40.57) 100.05,100.93) Nominal 160 mg formulation 0.5570 (O.SS66,0.S600, 0.5635, 163.76 (162.93,166.27,167.1 I, 1.81 293.99 (292.72,296.92,296.56, 0.93 * Mean (individual determinations).+ n = 5 . 0.5502 ~ 0.5547) 159.79,162.72) 290.42,293.35)750 ANALYST, JULY 1993, VOL. 118 Extraction From Tablet Matrix Using Modified Supercritical Carbon Dioxide For example, at SO "C the methanokarbon dioxide contains two phases if the pressure is <9S bar (9500 kPa). Modifier The inability of supercritical carbon dioxide to extract compounds that are polar has been highlighted by several workers.2.3 However, the solvating ability of supercritical carbon dioxide can be increased by the addition of modifiers or co-solvents.Conditions necessary to maintain supercritical conditions in the presence of modifiers are well known and recent work4 has highlighted the requirement to ensure that only one phase is present at the selected extraction conditions. Table 5 Effect of extraction time on the recovery of megestrol acetate from a ground tablet using supercritical carbon dioxide Mass of sub-sample/ Time/min mg 5 20.00 10 22.20 15 19.99 20 20.00 25 22.00 30 22.00 Mass of mcgestrol acetate in sub-sample*/ mg 5.88 6.53 5.88 5.88 6.46 6.46 Mass of megestrol acetate recovered/ mg 3.19 4.06 3.61 4.14 4.04 3.50 ' Using mean assay value of 293.99 mg g-l.Recovery 54.3 62.2 61.4 70.4 62.5 54.2 ("/. 1 (10%; methanol) can easily be introduced using the Jasco system via a second reciprocating pump. A similar experiment to that described above was repeated using a ground 160 mg tablet and the results are shown in Table 6. The reported recoveries are significantly higher in the presence of modifier than those reported without modifier (Table 5 ) . Also, maxi- mum recovery (92.8%) was obtained after 20min. These results demonstrate the necessity to add modifier as an aid to SFE, in the presence of a matrix, even for analytes that are known to be soluble in supercritical carbon dioxide. I t is concluded that the presence of a modifier is required to aid diffusion/desorption of the analyte from its matrix.Effect of Sample Mass on Recovery of Megestrol Acetate From a Tablet Using Modified Supercritical Carbon Dioxide Using the optimum conditions previously determined for the SFE of megestrol acetate from a ground tablet matrix, i.e., 0.81 g ml-1, 55 "C and 10% methanol (as modifier) the effect of sample mass was investigated. Five 160 mg tablets were ground to powder form and sub-sampled to give masses of 10, 15, 20, 25, 40 and 50mg. The results, shown in Table 7 , indicate that extraction is independent of sample mass. Table 6 Effect of extraction time on the recovery of megestrol acetate from a ground tablet using methanol-modified supercritical carbon dioxide Mass of Mass of megestrol megestrol Mass of acetate in acetate sub-sample/ sub-sample*/ recovered/ Recovery Time/min mg mg mg (Yo 1 5 20.40 6.00 4.68 78.0 10 21 .OO 6.17 5.38 87.2 1s 20.80 6.11 5.54 90.7 20 23.20 6.82 6.33 92.8 2.5 20.60 6.06 4.95 81.7 30 21.20 6.23 4.91 78.8 * Using mean assay value of 293.99 mg g-'.Table Assay Using Modified Supercritical Carbon Dioxide Each tablet formulation (40 and 160 mg active ingredient) was assayed using modified supercritical carbon dioxide at a density of 0.81 g 1171-1, 55 "C and with 10%" methanol added. The assay was carried out using five tablets of each formula- tion ground to a fine powder in a mortar with a pestle and sub-sampled. The results using modified supercritical carbon dioxide are shown in Table 8. A comparison of SFE with the USP method is shown in Table 9.Conclusions It is clear that SFE introduced some degree of variability into the procedure studied; this will need to be addressed if SFE is Table 7 Effect of sample mass on the recovery of megestrol acetate from a ground tablet using methanol-modified supercritical carbon dioxide Mass of tablet sub-sample/mg 10.50 14.90 23.20 30.10 41 .OO 50. 00 Mass of megestrol acetate in sub-sample*/mg 3.09 4.38 6.82 8.85 12.05 14.70 Mass of megestrol acetate recovered/mg Recovery (YO) 3.23 104.5 4.22 96.3 6.33 92.8 9.08 102.6 11.84 98.3 14.87 101.2 * Using mean assay value of 293.99 mg g-l Table 9 Comparison of USP monograph and SFE assay values USP SFE mg mg mg g-1 per tablet mg g-1 per tablet 40 mg Tublets- Mean 100.3 40.5 98.0 39.5 RSD* (%) 0.4 0.9 4.3 4.9 160 mg Tablets- Mean 294.0 153.8 303.1 169.4 RSD* (Yo) 0.9 1.8 3.0 3.1 * n = 5 .Table 8 Tablet assay results using modified supercritical carbon dioxide Tablet RSDl RSD' Tablet mass'/g Assay value*/per tablet (% 1 Assay valuc*/mg g- (Yo 1 Nominal 40 mg formulation 0.4030 (0.3985,0.043,0.4020, 39.50 (37.76,41.30,37.29, 4.9 98.00(94.74,102.15,92.77. 4.3 0.4065,0.4035) 41.43.39.71) 101.92.98.41) Nominal 160 mg formulation 0.5588(0.5588,0.5580,0.5593, 169.40(169.69,165.99,175.46, 3.1 303.07(303.66,297.05,313.72, 3.0 * Mean (individual determinations). + n = 5 . 0..5600,0.5578) 173.38,162.50) 309.60,29 1.33)ANALYST, JULY 1993, VOL. 118 75 1 to compete as a sample preparation technique with approved methods in the pharmaceutical industry. However, SFE could well replace approved methods if the extraction and assay occurred in a single step using the in-line UVNIS detector. This would provide a more simple analytical procedure than the USP method and the possibility for automation. The authors acknowledge the assistance of M. Kane in the operation of the SFE instrumentation, Glaxo Manufacturing Services for providing the megestrol acetate standard and Bristol-Myers Ltd. for the Megace tablets. The loan of the HP7680A from Hewlett-Packard (UK) Ltd. is also acknow- ledged. In addition, financial support from ICI plc (Dr.s W. R. Campbell and C. J. Dowle) and Glaxo Manufacturing Services (K. Leiper and Dr R. L. Tranter) is gratefully acknowledged. References 1 Gorog, S . , and Szasz. G. Y., Analysis of Steroid Hormone Drugs, Elsevier, Amsterdam. 1978. 2 Hawthorne, S . B . , Anal. Chem., 1990,62, 633A. 3 Dean, J . R., Applications of Supercritical Fluids in Industrial Analysis. Chapman and Hall, London, 1993. 4 Page, S. H., Sumpter, S. R., and Lee, M. L., J . Microcolumn Srp., 1992, 4, 91. 5 Li, S. F. Y., Ong, C. P. Lee, M. L., and Lee, H. K . , J. Chrornatogr., 1990,515, 515. 6 Kane, M., Dean. J. R., Hitchen, S . M., Dowle, C. J . , and Tranter, R. L., Anal. Chim. Acta, 1993, 271, 83. 7 United States Pharmacopeia, USP XXIIlNutional Formulary XVZZ, US Pharmacopeial Convention, Rockville, MD, 1990, Paper 2f06542H p. 815. Received December 9, 1992 Accepted February 3, I993

ISSN:0003-2654    

DOI:10.1039/AN9931800747

出版商:RSC    

年代:1993

数据来源: RSC