ISSN:0003-2654    

DOI:10.1039/AN99520FX015

出版商:RSC    

年代:1995

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN99520BX017

出版商:RSC    

年代:1995

数据来源: RSC

摘要:

Analyst, April 1995, Vol. 120 41N Book Reviews Chemical Analysis by Nuclear Methods Edited by Z. B. Alfassi. Pp. xx + 556. Wiley. 1994. Price f90.00. ISBN 0-471-93834-3. This text, written by a group of 25 specialist authors from ten different countries, provides a comprehensive review of the wide range of nuclear techniques that can be employed in chemical analysis. The book comprises 20 self-contained chapters with appropriate references up to 1993. The text is divided into five sections dealing with: (1) basic background in nuclear physics and chemistry; (2) elemental analysis with neutron sources; (3) elemental analysis with particle accelera- tors; (4) use of radioactive (alpha, beta and gamma) sources; and ( 5 ) use of radiotracers. The book provides a good balance between rigorous, mathematically-based treatment of theoretical aspects of the subject and reviews of practical applications.The 5 chapters forming Part 1 provide essential background information on interaction of radiation with matter, instrumentation, radiation sources, prompt and delayed measurements and radiation protection. Part 2, containing 4 chapters devoted to the use of neutrons in chemical analysis, includes detailed consideration of the various methods of neutron activation analysis and descriptions of neutron thermalization, scattering and absorption techniques. Part 3, with 5 chapters, deals with analysis using particle accelerators and includes charged particle activation analysis, charged particle scattering and recoil methods, particle induced X-ray emission and microprobes.In Part 4, which contains 4 chapters, descriptions are given of the use of radioactive sources for X-ray fluorescence analysis, radiation scattering techniques, Mossbauer spectroscopy and analytical methods based upon positron annihilation. Finally, Part 5 has two chapters dealing with isotope dilution analysis and radio- immunoassay . ‘This text, written by a group of 25 specialist authors from ten different countries, provides a comprehensive review of the wide range of nuclear techniques that can be employed in chemical analysis.’ The last two decades have seen a rapid expansion in the use of nuclear techniques for analytical purposes and this book provides a valuable addition to the literature by bringing together descriptions of more than 70 of such methods (and their acronyms).The growing importance of nuclear analy- tical methods is indicated by the applications described in a diverse range of disciplines including medicine, biology, environmental studies, agriculture, geology, archaeology, metallurgy, semiconductors, on-line production monitoring, nuclear fuel analysis, monitoring of nuclear fuel storage pond water, oil-well borehole logging and airport security. The text is generally well written, but with a surprising number of typographic errors and considerable variations in style and ease of reading between chapters. There is some degree of repetition of aspects that are common to more than one method (e.g., radiation sources and instrumentation) but this has been minimized to a level consistent with making each chapter self contained.This book, providing a detailed, quantitative treatment of the subject matter. will primarily be of value to chemists and physicists at honours degree or research level and would be a useful addition to appropriate libraries or for individual use by those actively involved in this area. The background information and descriptions of appli- cations will also be of considerable value for ‘customers’ in other disciplines who make use of the analytical methods. A. B. MacKmzie Scottish Universities Research & Reactor Centre Glasgow, UK Flame Chemiluminescence Analysis by Molecular Emission Cavity Detection Edited by David Stiles, Anthony Calokerinos and Alan Townshend. Volume 729 in Chemical Analysis: A Series of Monographs on Analytical Chemistry and its Applica- tions.Series Editor, J. D. Windfordner. Pp. vii + 206. Wiley. 1994. Price f50.00. ISBN 0-471-94340-1. Molecular emission cavity analysis (MECA) was first reported in 1973 by Belcher, Bogdanski and Townshend. It was developed from a qualitative flame test for bismuth (from Feigl’s Spot Tests in Inorganic Analysis) which, when mixed with alkaline earth carbonates, gives a cornflower-blue colouration to a hydrogen flame. This phenomenon is now known as candoluminescence and MECA is essentially the quantitative measurement of this phenomenon. The sulfur/ phosphorus detector (flame photometric detector) used in gas chromatography is probably the most well known example of qualitative analysis based on emissions from cool hydrogen- based flames.For the potential user, MECA instrumentation is no longer commercially produced but purpose built appa- ratus can be constructed relatively easily from a flame photometer. ‘Recommended for its complete coverage of the historical development and current status of MECA and for the obvious enthusiasm that the contributors have for the technique’. The major attraction of the technique is its good sensitivity for non-metals, particularly sulfur, phosphorus and the halides, a fact that is emphasized by the contents of this book. The first three chapters cover historical aspects, basic prin- ciples, instrumentation and automation. Particularly impor- tant in this regard is the design of the cavity itself, which is most commonly a metallic or carbon rod in which a small aperture is cut to accommodate the sample.The remaining four chapters cover in detail the application of the technique to the determination of various groups of compounds, namely; sulfur, selenium and tellurium; arsenic, antimony, boron, silicon, germanium and tin; nitrogen, phosphorus and carbon; and halogens and metals. The most significant aspects of these chapters are that the technique can be used for analysis of solids (as well as gases and liquids), e.g., sulfur in coal, and for the speciation of elements, e.g., the determination of organic and inorganic species containing phosphorus and the analysis of S2-, SO3’- and S042- in a single run. This book, which is volume 129 in the Chemical Analysis series published by Wiley, is well presented and easy to read and is the only comprehensive account of a niche technique in atomic spectrometry. It may well be that with modern array detectors there is some scope for revisiting a technique that is currently pursued by a small but dedicated band of research- ers.The reference lists cited at the end of each chapter show that there was a steady output of papers throughout the 1970s and 1980s.42N Analyst, April 1995, Vol. 120 I t is rccomrnended for its complete coverage of the historical development and current status of MECA and for the obvious enthusiasm that the contributors have for the technique. P. J . Worsfold Department of Environmental Sciences IJniversity of Plymouth, UK Fluorescent Chemosensors for Ion and Molecule Recognition Edited by Anthony W.Czarnik. ACS Symposium Series 538. Pp. x + 236. Price US $69.95. American Chemical Society. 1994. ISBN 0-841 2-2728-4. This book, developed from a symposium of similar title, contains a series of specialist papers consisting of past and current research plus reviews on the topic, and is written by experts from a wide range of fields. It is presented in a camera ready type publication format in order that the symposium papers could be published as soon as possible. All papers address the fluorescent chemosensor field and the valuable contributions that synthetic organic chemists can make to this important technology. Application papers deal with sensing of many biological analytes of importance in the biomedical field. The book, on the whole, stresses the need for the design and synthesis of a wide variety of receptors for ions and molecules, and the need for more basic research to accomplish and realise working chemosensory systems.‘The book stresses the need for the design and synthesis of a wide variety of receptors for ions and molecules, and the need for more basic research to accomplish and realise working chemosensory systems’. The book contains 13 chapters, all dealing with some fundamental aspect of fluorescent chemosensors. Chapter 1 deals with the basics of supramolecular chemistry, fluores- cence and sensing supported by an excellent bibliography. The synthesis of crown ether-type reagents are discussed in Chapter 2 with a view to develop alkali metal ion sensors and also includes a discussion on the different schemes used to accomplish this.Chapters 3 and 4 present comprehensive notes on the detection of ions and molecules using photo- induced energy transfer mechanisms. Molecular recognition of organic compounds are discussed in Chapters 5 and 6; while the former discusses a variety of new supramolecular systems with fluorescence emission of the receptor molecule tunable to the guest molecule, the latter presents molecular recognition by the use of chromophore modified cyclodextrin molecules. Both chapters emphasize the structural aspects of recognition molecules. Chapter 7 deals with the incorporation of chromo- phores and fluorophores into the structure of a synthetic molecular receptor resulting in ‘intrinsic’ chemosensor systems. Chapter 8 discusses the mechanisms of recognition and of fluorescent signal transduction using a variety of examples involving guests such as cations, anions and car- bohydrates.Chapters 9 to 11 discuss, in somewhat detail, the use of fluorescent probes for the detection and measurements of ions/molecules in cells and blood, particularly calcium and potassium ions. Chapter 12 similarly discusses the use/applica- tion of fluorescent probes in studics pertaining to proteases. Finally, Chapter 13 is devoted to sensors based on fluores- cence lifetime rneasuremcnts with discussions on the advan- tages of the technique by the use of flow-cytometry and its potential use in fluorcsccnce microscopy. The references provided at the end of each chapter are fairly comprehensive and cover the literature up to 1992.This book provides information of great value of those involvcd, or those that wish to become involved in the field of optical fluorescence based sensors, and is considered to be a useful reference text. The material is well presented and the choice of topics reflects a good balance. The book has been produced in hardback form and is priced at a reasonable level for a book of this type. I t is highly recommended. R. Narayanaswamy Department of Instrumentation and Analytical Science UMIST, Manchester LIMS: Implementation and Management By Allen S. Nakagawa. Pp. xiv + 180. Royal Society of Chemistry. 1994. Price f37.50. ISBN 0-851 86-8241X. The preface of the text has some well chosen aims for the volume. It asks, in respect of Laboratory Information Management Systems (LIMS), the following questions.Are the costs justified? Do they make organizations stronger or do they just increase overheads? Are LIMS only appropriate for certain laboratories? How should the technology be evaluated and implemented? The measure of the book’s value is best judged by how well the above are answered. For many laboratories (deciding on LIMS purchase) the purchase decision is made on the basis of a consultant’s investigation and report. The book could well be regarded as a consultant’s methodology and would form a sound basis for a laboratory manager to perform a DIY exercise on LIMS purchase and implementation. The book contains several potentially interesting case studies, but deals with them in a superficial manner, which contrasts with its more comprehensive approach to the issues surrounding LIMS.One case study cites the software develop- ment needing 25 years of effort, but with a projected benefit of 15 to 20 years of effort per year, both difficult concepts to digest in that type of unit measure. Another study suggests an over-all productivity improvement of 30%, with payback of the system occurring within one year. The studies are there to attempt to answer the question; are LIMS costs justified and the intended answer is that for some laboratories they appear to be cost effective. Other examples suggest an increase in workload concomitant with staff reduction. In those instances one is left pondering if the LIMS introduction may have provided a convenient opportunity for re-organization, thus, clouding the actual benefits of the LIMS introduction. ‘The book is genuinely honest and helpful in its treatment of common misconceptions of LIMS introduction’.A chapter is devoted to the effects of LIMS on the laboratory operation and includes consideration on individual work patterns and methods of work. This is a novel and useful piece of narrative to those who live in a laboratory environ- ment, but one suspects the ideas are closely derived from manufacturing industry and the impact of automation. The book is genuinely honest and helpful in its treatment of common misconceptions of LIMS introduction. The book adequately demonstrates LIMS strengthening of laboratory management, simply by the availability of timely and useful information.Without such systems, how many large labora- tories would accurately know their workload and current output *?Analyst, April 1995, Vol. 120 43N ~~~~~~~ ~ ~ In respect of technology employed, LIMS are simply a reflection of general hardware and software computer deve- lopment. Nothing is demonstrated in the text that shows LIMS to be unique or especially demanding in the technology applied. The text is a useful and essential aid in laboratory management (with or without LIMS) and I recommend it to all concerned with labratory management. David Rest Yorkshire Water Bradford, UK The Colloidal Domain: Where Physics, Chemistry, Biology and Technology Meet By D. Fennel Evans and Haksn Wennerstrom. Pp. xxxii + 516. VCH (Weinheim). 1994.Price. DM98.00. ISBN 1-56081 -525-6. Every book naturally reflects the interests of the author(s), and this one is no exception. Evans and Wennerstrom have approached their explanation of ‘The Colloidal Domain’ by concentrating on association colloids formed by molecular self-assembly, rather than relying on the more traditional lyophobic colloids as examples. The book is based on lectures given by the authors at the University of Minnesota and its primary value will be as an aid for teaching colloid science in university or college courses. It forms part of the Advances in Interfacial Engineering Series published by VCH Publishers. As a text book, it covers the usual aspects found in ‘traditional’ works, albeit in the unconventional style of approaching colloid and interface science from the different perspective of self-assembled structures.The authors have taken the trouble to explain their reasoning behind this approach. To aid learning, the authors have used sentenced statements as chapter headings and sub-headings, and the provision of ‘concept maps’ summarizing the contents of each chapter. At the end of each chapter, examples/questions (which are particularly useful) and a limited bibliography based on established texts are provided. To anyone experienced in the field, this book offers limited new material or interpretation. Some areas have been covered well, especially the treatment of colloidal forces, phase behaviour, solvency, micellization and the role of polymers in colloid science, whereas other aspects normally regarded as being fundamental to the subject, have been given less attention.For example, even considering their technological importance, lyophobic colloids have mainly been used to illustrate principles, and the authors have avoided dealing specifically with experimental methods in their own right, preferring instead to describe or discuss techniques where and when they are associated with, or relevant to, a particular topic. In taking this approach, some discussions are far from comprehensive, e.g., rheology is briefly covered in connection with polymer systems, and in the section on surface/interfacial tension, only passing reference is made to the importance of ‘dynamic’ surface effects, with no reference being made to the measurement of dynamic tensions.‘Students of colloid science may benefit from its modem style, and the principles which it describes are sound. For the more experienced reader or researcher, however, it is unlikely to displace established texts as a reference book.’ Even though amphiphiles provide the foundation of the book, discussion on commercial aspects and applications (technology) of surfactants arc largely absent (the HLB concept, however fragile it may be regarded, is mentioned once!). In fact, as one attracted by the title, I was disappointed that examples of the meeting of physics, chemistry, biology and (unashamedly as an industrialist, especially) technology that have been discussed in any detail in ‘The Colloidal Domain’ are themselves only dispersed very thinly throughout the 500+ pages.In their introduction, the authors observe, rightly in m y opinion, that ‘Nearly all industrial processes involve colloidal systems’. However, the attention given to association colloids has restricted the scope of the book almost exclusively to aqueous-based systems, with some brief excursions into the realms of polar non-aqueous solvent systems, in line with the authors‘ interests. A further disappointment is that little or no consideration has been given to non-polar systems which, arguably, form the basis of many industrial processes and products which ‘involve colloidal systems.’ Notwithstanding the shortcomings of this book in terms of content and approach, ‘The Colloidal Domain’ has been well-produced, with newcomers to the subject in mind.Students of colloid science may benefit from its modern style, and the principles which it describes arc sound. For the more experienced reader or researcher, however, it is unlikely to displace established texts as a reference book. S. E. Taylor Applied Science Group BP Research and Engineering Centre Middlesex, UK Environmental Analysis By Roger N. Reeve. Analytical Chemistry by Open Learning. Pp. xx + 264. Wiley. 1994. Price f19.50. ISBN 0-471 -93833-5. Environmental Analysis is one of a series of ACOL (Analy- tical Chemistry by Open Learning) books, of which there are already 32 books and 8 computer-based packages. The books are designed to be easy to read and are for training, continuing education and updating in the various fields of analytical chemistry. Details are given in the book about how to achieve full benefit from them.In addition to a study guide and bibliography the book discusses the reasons for concern about the environment and has chapters on the transport of pollutants in the environment, the analysis of water (both for main components and for trace analysis), analysis of gases, of solids, of particulates in the atmosphere, and a chapter about ultra-trace analysis. Throughout the book there are numerous small ‘boxes’ containing ‘self-assessment questions’ pertinent to the imme- diate text, spaces being left, presumably, for the answers and for discussion. ‘The importance of careful and meaningful sampling procedures is stressed throughout, and types of samplers and analysers are dis- cussed where relevant’. Analytical techniques to which references are made in this book, and of which a basic knowledge by the reader is assumed, include: atomic absorption spectrometry and flu- orescence; chemiluminescencc; inductively coupled plasma- mass spectrometry; inductively coupled plasma-optical emis- sion spectrometry; gas, ion, and high-performance liquid chromatography; emission and X-ray spectrometry; and infrared spectrometry, among others.44N Aiinlyst, April 1995, Vol.120 The importance of careful and meaningful sampling proce- dures i s stressed throughout, and types of samplers and analysers are discussed where relevant. There are numerous useful illustrations throughout, some of which appear to be hand drawings (with rather an unusual perspective shown in the drawing of Kjeldahl apparatus).There appears to be an error in the formula shown for o,p’-DDT inasmuch as an additional chlorine is included, and this affects the example illustrating increase of water solubil- ity. Nevertheless, this is a useful little book, not over- expensive, and I would recommend it for purchase by people involved in such environmental studies and by libraries (although it is not to be expected that the latter would appreciate borrowers writing or drawing in the book in the spaces provided). D. Simpson Analysis For Industry Essex, UK planning to analyse cationic surfactants in almost any system. Important practical details specific to cationic surfactants, such as ways of overcoming the interfering effects of ubiqui- tous anionic surfactant and the difficulties caused by the surfactant’s propensity to adsorb strongly on solid surfaces, are adequately described.This book is a valuable addition to the Surfactant Science Series and a useful companion to Volume 37 (‘Cationic Surfactants; Physical Chemistry’). Its cost is likely to deter private owners but it should be an essential addition to the libraries of any institution; academic, research or industrial, that has an interest in cationic surfactants. B. T. Ingram Procter & Gamble Limited Newcastle Upon Tyne, UK Cationic Surfactants. Analytical and Biological Evalua- tion Edited by John Cross and Edward J. Singer. Pp. viii + 374. Marcel Dekker. 1994. Surfactant Science Series. Volume 53. Price US$150.00. ISBN 0-8247-9177-0. An earlier volume on cationic surfactants in the Surfactant Science Series devoted 64 pages to analytical evaluation but now Johii Cross, the author of that 1970 review and co-editor of this new volume, has assembled a group of authors whose chapters on analysis cover 232 pages.This expansion demon- strates not only the improvement in analytical techniques but also the increasing importance of being able to detect and analyse cationic surfactants in particular. Although cationic surfactants have a wider variety of applications than any other type of surfactant their share of the total surfactant market is less than 10%. Nevertheless, annual usage is several hundred kilotonnes and is still rising. Most of this comes from the use of cationic surfactants as textile conditioners and fabric softeners.However, the biological activity of cationic surfactants, which incidentally gives them several useful applications, produces a greater risk of environmental damage than with anionic and non-ionic surfactants and it is for this reason that analysis of cationics has received increasing attention. The biological aspects are dealt with in the section edited by Edward Singer. Chapters on ‘Biological Properties and Applications of Cationic Surfactants’ (Fredell), ‘Current Topics on the Toxicity of Cationic Surfactants’ (Drobeck), and ‘Environmental Aspects of Cationic Surfactants’ (Boeth- ling) give comprchensive coverage of properties, test methods and references. ‘An essential addition to the libraries of any institution; academic, research or industrial, that has an interest in cationic surfactants.’ The second section covers analytical evaluation.Chapters written by experienced practitioners on ‘Volumetric Analysis’ (Cross), ‘Potentiometry’ (Moody and Thomas), ‘Tensammet- ric Determination’ (Bos), ‘Analysis of Low Concentrations of Cationic Surfactants in Laboratory Test Liquors and Environ- mental Samples’ (Waters), ‘Mass Spectrometry’ (Kalinoski), ‘Chromatography’ (McPherson and Rasmussen), and ‘Mole- cular Spectroscopy’ (Mozayeni) will be useful to anyone Solution Calorimetry Edited by K. N. Marsh and P. A. G. O’Hare. Experimental Th ermo d yn am ics. Volume I V. IU PAC Commission on Thermodynamics. Pp. xviii + 332. Blackwell. 1994. Price f69.50. ISBN 0-86542-852-2. Some years ago calorimetry was a branch of research that was pursued in a reasonable number of University Research Schools in Chemistry within the UK.This area of research has seen a decline in interest within the UK and most development and interest is now shown by continental Europeans, together with American and East European colleagues. Perhaps the time has arrived for there to be a resurgence in calorimetry in the UK, although the volume reviewed here has (strictly) only one contributor from the UK. Proving that the subject is very much alive and perceived as important is evidenced by the appearance of these IUPAC sponsored volumes. ‘rich variety of material to be found within this volume, however, the information is for the specialist’ This book, the fourth in the series, is a pleasure to review. It, like the previous volumes, has an impressive list of contributors; all experts in the field. The contributions range widely from; Reduction to Standard States (Vanderzee: to whom, together with Stanley Gill, the book is dedicated) through Excess Enthalpies by Flow Microcalorimetry (Ott and Wormald) via Aqueous and Biological Systems (Wadso) to Calorimetric Determination of Pressure Effects (Randzio). This, incomplete, listing gives some idea of the rich variety of material to be found within this volume. It also, however, gives a clear indication that the information is for the specialist although the calorimetrist with a desire to be informed over the range of solution phase calorimetry should emerge from reading this book well informed and stimulated. Necessarily in a book of this coverage of a particular, and hugely important area, a reviewer can find some, albeit small, deficiencies. Amongst these I am surprised at the. rather limited coverage given to titration calorimetry, especially in the area of biological studies, given the appearance of high sensitivity, rapid titration equipment. This small objection apart, the book is welcomed as a most useful addition to, in the main, library shelves. A . E. Beezer Chemical Laboratory The University, Canterbury, Kent, UK

ISSN:0003-2654    

DOI:10.1039/AN995200041N

出版商:RSC    

年代:1995

数据来源: RSC

摘要:

Analyst, April 1995, Vol. 120 45N Conference Diary Date 1995 3 May 7-10 7-1 1 7-1 1 9-12 14-18 16-18 20-24 21-25 21-26 21-26 22-24 28-216 June 5-7 5-8 6-9 Conference Location New Techniques in Bioanalysis Bradford, UK Handling of Environmental and Biological Samples in Chromatography Sweden Lund , 86th AOCS Annual Meeting & Expo Texas, USA Seventeenth International Symposium on Virginia, Capillary Chromatography and USA Electrophoresis Metal Compounds in Environmental and Life Jiilich, Sciences &Analysis, Speciation and Specimen Germany Banking EMAS 95 on Modern Developments and St Malo, Applications in Microbeam Analysis France Fourth International Conference on Progress Luxembourg in Analytical Chemistry in the Steel and Metals Industry Electron Microscopy in Solid State Science Lund, Sweden ASMS Conference on Mass Spectrometry Atlanta, USA CLEO '95: Conference on Lasers and Electro- Baltimore, Optics USA QELS '95: Quantum Electronics and Laser Science Conference USA Baltimore, Eighth International Symposium on Polymer Analysis and Characterization (ISPAC-8) USA Sanibel Island, 19th International Symposium on Column Liquid Chromatography Austria Innsbruck, Image Techniques and Analysis in Fluid Mechanics Italy Rome, 5th Symposium on our Environment and 1st Asia-Pacific Workshop on Pesticides Singapore Convention City, 8th International Symposium on Loss An twerp, Prevention and Safety Promotion in the Process Belgium Industries Contact A.J. Crooks, 'Cartref', 35 Queensbury Road, Salisbury, Wiltshire, UK SP1 3PH Tel: +44 (0)1722 334974.Mrs. M. Frei-Hausler, Postfach 46, CH-4123 Allschwil 2, Switzerland Fax: +41 61 482 0805 AOCS EducationMeetings Department, P. 0. Box 3489, Champaign, IL 61826-3489, USA Tel: +1 217 359 2344. Fax: +1217 351 8091 Dr. Milton L. Lee, Department of Chemistry, Brigham Young University, Provo, UT 84602- 4672, USA Tel: +1 801 378 2135. Fax: +1 801 378 5474 H. W. Durbeck, Institute of Applied Physical Chemistry, Research Center Jiilich (KFA), P.O. Box 1913, D-5170 Jiilich, Germany EMAS Secretariat, RIKILT-DLO, P.O. Box 230, 6700 AE Wageningen, The Netherlands R. Jowitt, British Steel plc, Technical, Teesside Laboratories, P.O. Box 11, Grangetown, Middlesbrough, Cleveland, UK TS6 6UB Fax: +44 (0)1642 460321 A. Sjogren, The Swedish National Committee for Chemistry, Walligatan 24 3 Tr, 11124 Stockholm, Sweden ASMS, 815 Don Gaspar, Santa Fe, NM 87501, USA Tel: +1 505 989 4517 Meetings Department, Optical Society of America, 2010 Massachusetts Avenue, NW, Washington, Tel: + 1 202 223 9034.Fax: + 1 202 416 6100 Meetings Department, Optical Society of America, 2010 Massachusetts Avenue, NW, Washington, Tel: +1 202 223 9034. Fax: +1 202 416 6100 ISPAC Registration, 815 Don Gaspar, Sante Fe, NM 87501, USA Tel: +1 505 989 4735. Fax: +1 505 989 1073 HPLC '95 Secretariat, Tyrol Congress, Marktgraben 2, A-6020 Innsbruck, Austria Tel: +43 512 575600. Fax: +43 512 575607 DC 20036-1023, USA DC 20036-1023, USA. A. Cehedese, Department of Mechanics and Aeronautics, University La Sapienza, Via Eudossiana 18, 00184 Rome, Italy The Secretariat, 5th Symposium on our Environment, c/o Department of Chemistry, National University of Singapore, Kent Ridge, Republic of Singapore 0511 Fax: +65 779 1691 The Organising Committee, 8th International Symposium on Loss Prevention, c/o Ingenieurshuis V2W, Desguinlei 214, B-2018 Antwerpen, Belgium46N Analyst, April 1995, Vol.120 Date 7 7-9 11-14 12-16 13-16 July 2-6 2-7 9-13 9-14 9-15 10-13 30-5/8 Conference Location Joint Meeting of the Molecular Spectroscopy Oxford, Group and the Infrared and Raman Discussion UK Group-Vibrational Spectroscopy and Imaging LIMS 95-International Conference and Bonn, Exhibition Germany 1995 International Symposium, Exhibit and Workshops on Preparative Chromatography, USA Ion Exchange, and AdsorptionDesorption Processes Washington DC, 50th Annual Molecular Spectroscopy Columbus, Symposium USA ESIS 95-New Infrared Spectroscopy and Microspectroscopy: FTIR and Raman France Lyon, VII International Congress of Toxicology Seattle, USA 12th International NMR Meeting Manchester, UK 3rd International Symposium on Applied Mass Barcelona, Spectrometry in Health Sciences and 3rd Spain European Tandem Mass Spectrometry Conference 13th Australian Symposium on Analytical Chemistry/4th Environmental Chemistry Australia Conference Darwin, SAC 95 Hull, UK Vth COMTOX Symposium on Toxicology and Vancouver, Clinical Chemistry of Metals Canada XXIInd International Conference on Hoboken, Phenomena in Ionized Gases USA August 5-10 1995 International Symposium on Soil and Wageningen, Plant Analysis The Netherlands 6-11 NIR '95-The Future Waves Montreal, Canada 13-17 ICFIA '95, 7th International Conference on Seattle, Flow Injection Analysis and JAFIA, Japanese Association for Flow Injection Analysis USA 14-16 41st International Conference on Analytical Windsor, Science and Spectroscopy Canada Contact Dr.J. M. Chalmers, ICI plc, Wilton Research Centre, P.O. Box 90, Wilton, Middlesbrough, UK TS90 8JE JAY Conference Services, 45 Hilltop Avenue, Hullbridge, Hockley, Essex, UK SS5 6BL Mrs. Janet Cunningham, PREP '95 Symposium/ Exhibits Manager, Barr Enterprises, 10120 Kelly Road, P.O. Box 279, Walkersville, MD 21793, USA Tel: + 1 301 898 3772. Fax: + 1 301 898 5596 T. A. Miller, International Symposium on Molecular Spectroscopy, Department of Chemistry, Ohio State University, 120 West 18th Avenue, Columbus, Ohio 43210, USA G.Lachenal, Laboratoire des Materiaux Plastiques et Biomateriaux, Universite Claude Bernard Lyon 1,43 Boulevard du 11 Novembre, 69622 Villeurbanne Cedex, France Jada Hill, The Sterling Group, 9393 W, 110th Street, Suite, Overland Park, KS 66210, USA Tel: +1 913 345 2228. Fax: +1 913 345 0893 Dr. J. E. Gibson, Royal Society of Chemistry, Burlington House, Piccadilly, London, UK W1V OBN Professor Emilio Gelpi, Palau de Congressos, Departamento de Convencions, Avda, Reina Ma Christina, 08004 Barcelona, Spain 13AC/4EC, Symposium Secretariat, Convention Catalyst Int., GPO Box 2541, Darwin NT 0801, Australia Tel: +61 89 811 875. Fax: +61 89 411 639 Analytical Division, The Royal Society of Chemistry, Burlington House, Piccadilly, London, UK W1V OBN Tel: +44 (0)171437 8656.Fax: +44 (0)171 734 1227 F. William Sunderman, Jr., M.D., Departments of Laboratory Medicine and Pharmacology, University of Connecticut Medical School, P.O. Box 1292, Farmington, CT 06034-1292, USA Tel: + 1 203 679 2328. Fax: + 1 203 679 2154 E. E. Kunhardt, Physics Department, Stevens Institute of Technology, Hoboken, NJ 07030 USA Tel: +1 201 216 5099. Fax: +1201 216 5638 Soil and Plant Analysis Council, Georgia University Station, P.O. Box 2007, Athens, GA 30612-2007, USA Tel: + 1 706 546 0425. Fax: + 1 706 548 4891 NIR '95, The Canadian Grain Commission, Grain Research Laboratory, 1403-303 Main Street, Winnipeg, Manitoba, Canada R3C 3G8 Gary D. Christian, Department of Chemistry, BG-10, University of Washington, Seattle, WA 98195, USA Tel: +1 206 685 3478.Fax: +1 206 543 5340. E-Mail: christia@chem.washington.edu William E. Jones, Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario. Canada N9B 3P4Anulyst, April 1995, Vol. 120 47N Date 20-25 27-219 27-119 27-119 27-30 Conference Location 12th International Symposium on Plasma Chemistry USA Minneapolis, CSI XXIX: Colloquium Spectroscopicum Leipzig, Internationale Germany 46th Annual Meeting of the International Society of Electrochemistry (ISE46) China Xiamen, Third International Conference on Magnetic Resonance Microscopy Germany Wiirzburg, EUROTOX September 1-4 3-6 3-8 5-8 6-8 6-9 10-14 12-15 12-16 17-20 Prague, Czech Republic CSI XXIX, Post-symposium ICP-MS and 11th Wernigerode, German ICP-MS Users Meeting Germany Third International Meeting on Recent Louvain la Neuve, Advances in Magnetic Resonance Application Belgium to Porous Media 6th European Conference on the Spectroscopy Villeneuve of Biological Molecules d'Ascq, France RSC Autumn Meeting.Analytical and Faraday Sheffield, Symposium: Ions in Solution UK 5th Symposium on Chemistry and Fate of Modern Pesticides France Paris, Joint Meeting of the Royal Society of Chemistry Fast Reactions in Solution Discussion Group and the Molecular Spectroscopy Group on Ultrafast Processes in Laser Spectroscopy Ion-Ex '95, The Fourth International Conference and Industrial Exhibition on Ion Exchange Processes Norwich, UK Wrexham, UK 5th International Symposium on Drug Analysis Leuven, Belgium European Symposium on BiOS Europe '95: The European Biomedical Optics Symposium Week Barcelona, Spain 6th Surrey Conference on Plasma Source Spectrometry UK Jersey, Contact L.Graven, 315 Pillsbury Drive, SE, University of Minnesota, Minneapolis, MN 55455-0139, USA Tel: +l 612 625 9023. Fax: + l 612 626 1623 GDCh-Geschaftsstelle, Abt. Tagungen, Varrentrappestr. 40-42, Postfach 90 04 40, D-6000 Frankfurt am Main 90, Germany Tel: +49 69 791 7358. Fax: +49 69 791 7475 Secretariat, XLVIth ISE Annual Meeting, P.O. Box 1995, Xiamen University, Xiamen 361005, China Tel: 1-86 592 208 5349. Fax: +86 592 208 8054 Dr. A. Haas, Physikalisches Institute, Universitat Wiirzburg, Am Hubland, D-97074 Wiirzburg, Germany Czech Medical Association J. E. Purkyn6, EUROTOX '95, P.O.Box 88, Sokolska 31, 120 26 Prague 2, Czech Republic Tel: +42 2 24 915195. Fax: +42 2 24 216836 Professor Lieselotte Moenke, Department of Chemistry, Martin-Luther University, Halle- Wittenberg, Institute of Analytical and Environmental Chemistry, Weinbergweg 16, D-06120 Halle, Germany Professor J. M. Dereppe, Universitk de Louvain, Place L. Pasteur 1, B-1348, Louvain la Neuve, Belgium Professor J. C. Merlin, ECSBM '95, LASIR, UST Lille B5t. C5, 59655 Villeneuve d'Ascq Cedex, France Dr. J. F. Gibson, The Royal Society of Chemistry, Burlington House, Piccadilly, London, UK W1V OBN Tel: +44 (0)171 437 8656. Fax: +44 (0)171 734 1227 Mrs. Frei-Hausler, IAEAC Office, Postfach 46, CH-4123 Allschuril2, Switzerland Fax: +41 61 482 08 05 Professor B. H. Robinson, School of Chemical Sciences, University of East Anglia, Norwich, UK NR4 7TJ Ion-Ex '95 Conference Secretariat, Faculty of Science, The North East Wales Institute, Connah's Quay, Deeside, Clwyd, UK CH5 4BR Fax: +44 (0)1244 814305 Professor J.Hoogmartens, Institute of Pharmaceutical Sciences, Van Evenstraat 4, B-3000 Leuven, Belgium Tel: +32 16 32 34 40. Fax: +32 16 32 34 48 Ms. Karin Burger, BiOS Europe '95, EUROPTO Series, c/o Direct Communications GmbH, Xantener Strasse 22, D-10707 Berlin, Germany Tel: +49 30 881 SO 47. Fax: +49 30 881 50 40 E-Mail: Burger,100140.321 l@compuserve.com Dr. Kym Jarvis, NERC ICP-MS Facility, CARE, Imperial College, Silwood Park, Ascot, Berkshire, UK SL5 7TE Tel: +44 (0)1344 294517/6. Fax: +44 (0)1344 87399748N Analyst, April 199.5, Vol.120 Date Conference Location 17-21 109th AOAC International Annual Meeting Tennessee, and Exposition USA 24-28 11 th Asilomar Conference on Mass Pacific Grove, Spectrometry-Molecular Structure USA Determination: Activation, Mass Analysis and Detection 25-28 5th Symposium on 'Kinetics in Analytical Moscow, Chemistry' (KAC '95) Russia October 1-5 21st World Congress of the International The Hague, Society for Fat Research (ISF) The Netherlands 9-13 ECASIA '95 Montreux, Switzerland 15-20 22nd Annual Conference of the Federation of Cincinnati, Analytical Chemistry and Spectroscopy Societies 19-20 Biotechnology Now and Tomorrow 24-27 BCEIA '95-The International Sixth Beijing Conference and Exhibition on Instrumental Analysis 26-27 Sensors and Signals November 5-10 5-10 8-9 14-15 1st Mediterranean Basin Conference on Analytical Chemistry OPTCON '95 Biological Applications of Inorganic Mass Spectrometry International Conference for Chemical Information Users December 17-22 International Symposium on Environmental Biomonitoring and Specimen Banking 20-21 2nd LC/MS Symposium USA Bucharest, Romania Beijing, China County Dublin, Ireland Cordoba, Spain San Jose, USA Norwich, UK Manchester, UK Hawaii, USA Cambridge, UK Contact Meetings and Education Department, AOAC International, 2200 Wilson Boulevard, Suite 400, Arlington, Virginia, 22201-3301, USA Tel: +1 703 522 3032.Professor R. Graham Cooks, Department of Chemistry, 1393 Brown Building, Purdue University, West Lafayette, IN 47907, USA Dr. I. F. Dolmanova, Analytical Chemistry Division, Chemical Department, Lomonosov Moscow State University, 119899 Moscow, Russia Tel: +7 095 939 3346.Fax: +7 095 939 2579 Mrs. J. Wills, ISF Secretariat, P.O. Box 3489, Champaign, IL 61826-3489, USA Tel: +1 217 359 2344. Fax: +1 217 351 8091 EPEL-ECASIA 95, Department des Materiaud LMCH, CH-1015 Lausanne, Switzerland Fax: +4121 693 3946 Joseph A. Caruso, FACSS National Office, 198 Thomas Johnson Dr., Suite S-2, Frederick, MD 21702, USA Tel: +1 301 694 8122. Fax: +1 301 694 6860 Mrs. Gestiana Munteanu, Biotechnos S.A., Str. Dumbrava Rosie, nr. 18, Bucuresti 70254, Romania Tel: +40 1 210 20 15. Fax: +40 1 210 97 05 General Service Office, The International Sixth BCEIA, Room 585, Chinese Academy of Science Room, San Li He, Xi Jiao, P.O. Box 2143, Beijing 100045, China Dr. D.Diamond, School of Chemical Sciences, Dublin City University, Glashevin, Dublin, Ireland Tel: +353 1 704 5308. Fax: +353 1 704 5503 Professor Alfredo Sanz-Medel, Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, C/Julian Claveria, no. 8 33006 Oviedo, Spain Tel: +34 85 10 34 74. Fax: +34 85 10 31 25 Meetings Department, Optical Society of America, 2010 Massachusetts Avenue, NW, Washington, Tel: +1202 223 9034. Fax: +1 202 416 6100 Institute of Food Research, Norwich Laboratory, Norwich Research Park, Colney Lane, Norwich, UK NR4 7UA Dr. M. P. Coward, Chemistry Department, UMIST, P.O. Box 88, Manchester, UK M60 1QD Tel: +44 (0)161 200 4491. Fax: +44 (0)161228 1250 DC 20036-1023, USA K. S.Subramanian, Environmental Health Directorate, Health Canada, Tunney's Pasture, Ottawa, Ontario, Canada K1A OL2 Tel: +1 613 957 1874. Fax: +1 613 941 4545 Dr. J. Oxford, Glaxo Research and Development, Park Road, Ware, Hertfordshire, UK SG12 ODJAnalyst, April 1995, Vol. 120 49N ~ ~~ Oate Conference Locat ion 1996 January 8-13 1996 Winter Conference on Plasma Florida, Spectrometry USA 21-25 VIth Latin American Congress on Caracas, Chromatography Venezuela February 6-9 Fourth International Symposium on Bruges, Hyphenated Techniques in Chromatography Belgium (HTC 4); Hyphenated Chromatographic Anal ysers March 17-21 3 1-414 April 9-12 23-26 May 7-9 20-24 23-25 June 16-2 1 July 8-12 17-19 47th Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy USA Atlanta, 7th International Symposium on Supercritical Indianapolis, Fluid Chromatography and Extraction 26th International Symposium on Environmental Analytical Chemistry Analytica Conference '96 VIIth International Symposium on Luminescence Spectrometry in Biomedical Analysis-Detection Techniques and Applications in Chromatography and Capillary Electrophoresis 18th International Symposium on Capillary Chromatography XIIIth National Conference on Analytical Chemistry HPLC '96: 20th International Symposium on High Performance Liquid Chromatography XVI International Congress of Clinical Chemistry 8th Biennial National Atomic Spectroscopy Symposium (BNASS) USA Vienna, Austria Munich, Germany Monte-Carlo, Monaco Riva del Garda, Italy Craiova, Romania San Francisco, USA London, UK Norwich, UK Contact R.Barnes, Department of Chemistry, Lederle GRC Tower, University of Massachusettes, P.O. Box 34510, Amherst, MA 01003-4510, USA Tel: + 1 413 545 2294. Fax: + 1 413 545 4490 Irene Romero, Interep SA, P.O. Box 76343, Caracas 1070-A, Venezuela Dr. R. Smits, Royal Flemish Chemical Society (KVCV), Working Party on Chromatography, BASF Antwerpen N.V., Central Laboratory, Haven 725, Scheldelaan 600, B-2040 Antwerp, Belgium Tel: +32 3 561 2831. Fax: +32 3 561 3250 The Pittsburgh Conference, 300 Penn Center Boulevard, Suite 332, Pittsburgh, PA 15235-5503 USA Tel: +1 412 825 3220. Fax: +1 412 825 3224 Janet Cunningham, Barr Enterprises, 10120 Kelly Road, P.O. Box 279, Walkersville, MD 21793 USA Tel: +1 301 898 3772. Fax: +1 301 898 5598 Professor Dr. M. Grasserbauer, Institute for Analytical Chemistry, Vienna University of Technology, Getreidemarkt 9/151, A-1060 Wien, Austria Fax: +43 15867813 Congress Center, Messegelande, D-80325 Miinchen, Germany Tel: +49 89 5107 159. Fax: +49 89 5107 180 Professor Willy R. G. Baeyens, University of Ghent, Pharmaceutical Institute, Department of Pharmaceutical Analysis, Harelbekestraat 72, B-9000 Ghent , Belgium Tel: +32 9 221 8951. Fax: +32 9 221 4175 Professor D. P. Sandra, I. 0 .P.M.S., Kennedypark 20, B-8500 Kortrijk, Belgium Tel: +32 56 204960. Fax: +32 56 204859 Romanian Society of Analytical Chemistry, 13 Boulevard Repubiicii, Sector 3, 70346 Bucharest, Romania Tel: +40 1 631 00 60. Fax: +40 1 631 00 60 Mrs. Janet Cunningham, Barr Enterprises, P.O. Box 279, Walkersville, MD 21793, USA Tel: +1 301 898 3772. Fax: +1 301 898 5596 Mrs. Pat Nielsen, XVIth International Congress of Clinical Chemistry, P.O. Box 227, Buckingham, UK MK18 5PN Fax: +44 (0) 1280 6487 Dr. S. J. Haswell, School of Chemistry, University of Hull, Hull, UK HU6 7RX Tel: +44 (0)1482 465469. Fax: +44 (0)1482 466410

ISSN:0003-2654    

DOI:10.1039/AN995200045N

出版商:RSC    

年代:1995

数据来源: RSC

摘要:

SON Arzalyst, April IY95, Vol. I20 Courses Date 1995 M W 10 17 18 21 22-25 30-1/6 June 5-7 7-12 6-7 6-8 8 16-20 26-30 Conference Location Education and Training of Chromatographers London, UK Clinical Waste Meat Authenticity: Introduction to Immunoassay Test Kits Techniques for Polymer Analysis and Characterization Modern Practice of Gas Chromatography Sixteenth Annual Introductory HPLC Short Course Advanced HPLC Short Course 4th Annual Course on Practical Methods of Digestion for Trace Analysis Industrial Waste Water Part I 5th Annual Flow Injection Atomic Spectrometry Short Course DSC Calibration-Temperature, Enthalpy, Heat Capacity Short Course Capillary Electrophoresis, Routine Method for the Quality Control of Drugs: Practical Approach Radioisotope Techniques Short Course Sheffield, UK Campden, UK Sanibel Island, USA Pensy Ivania, USA Pensylvania, USA Pensylvania, USA Amherst, USA Sheffield, UK Amherst, USA Leeds, UK Mon tpellier , France Loughborough, UK Contact Dr.D. Simpson, Analysis for Industry, Factories 2/3, Bosworth House, High Street, Thorpe-le- Soken, Essex. UK C016 OEA Tel: +44 (0)1255 861714. Fax: +44 (0)1255 662111 Maria Baldham, The Division of Adult Continuing Education, The University of Sheffield, 196-198 West Street, Sheffield, UK S1 4ET Tel: +44 (0)114 282 5391. Fax: +44 (0)114 276 8653 Training Department, Campden Food and Drink Research Association, Chipping Campden, Gloucester, UK GL55 6LD Tel: +44 (0)1386 840319. Fax: +44 (0)1386 841306 Dr. Petr Munk, Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA Tel: +1 512 471 4179.Fax: +1 512 471 8696 Sally Stafford, Hewlett-Packard, Little Falls Site, 2850 Centerville Road, Wilmington, DE Tel: +1 302 633 8444 Bill Champion, DuPont Merck Pharmaceutical Company, PRF Building, Chambers Works, Deepwater, NJ 08023, USA Tel: +1 609 540 4826 19808-1610, USA Jim Alexander, Rohm and Haas Laboratories, 727 Norristown Road, Spring House, PA 19477, USA Tel: +1 610 619 5226 Nancy Teranto, Questron Corporation, 4044 Quakerbridge Road, Mercerville, NJ 08619, USA Tel: +1 609 587 6898. Fax: +1 609 587 0513 Maria Baldham, The Division of Adult Continuing Education, The University of Sheffield, 196-198 West Street, Sheffield, UK S1 4ET Tel: +44 (0)114 282 5391. Fax: +44 (0)114 270 8653 J. Tyson, Department of Chemistry, LGRC Tower, University of Massachusetts, Box 34510, Amherst, MA 01003-4510 USA Tel: +1 413 545 0195.Fax: +1 413 545 4846 Professor Edward Charsley, Head of the Thermal Analysis Consultancy Service, Leeds Metropolitan University, Calverley Street, Leeds LS1 3HE Tel: +44 (0)113 283 3121/3122. Fax: +44 (0)113 283 3120 Professor H. Fabre, Laboratory of Analytical Chemistry, Faculty of Pharmacy, 15 Avenue Charles Flahault 34060 Montpellier, France Tel: +33 67 54 45 20. Fax: +33 67 52 89 15 Dr. P. Warwick, Department of Chemistry, Loughborough University of Technology, Loughborough, Leicestershire, UK LEll 3TU Tel: +44 (0)1509 222585 Entries in the above listing are included 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 Analvst Editorial Office, Thomas Graham House, Science Park, Milton Road, Cambridge, UK CB4 4WF. Tel: +44 (0)1223 420066. Fax: +44 (0)1223 420247. E-mail:Analyst@RSC.ORG.

ISSN:0003-2654    

DOI:10.1039/AN995200050N

出版商:RSC    

年代:1995

数据来源: RSC

摘要:

Anul.yst, April 1995, Vol. 120 51N Conference Report Geoanalysis 94: An International Symposium on the Analysis of Geological and Environmental Materials* Geonanalysis 94 attracted more than 120 delegates from 25 countries including the USA, Canada, Australia, Russia, Sweden and the UK. The conference allowed for almost 100 oral and poster presentations embracing a wide field of analytical research. Although the conference officially opened on Monday, September 19th, the Conference Chairman, Doug Miles (BGS), gave a welcoming address diiting Sunday evening’s drinks reception, provided courtesy of Varian Ltd. Monday’s program was dedicated to the usage, production and development of reference materials. Dr. K. Govindaraju (Geostandards, CRPG), the first invited speaker, presented a lecture illustrating the features and attributes of the GeoStan series of databases.GeoStan allows easy computer access to a reference material database compiled from information col- lected by an international working group. The database represents over 900 pages of printed text and tables, making information on available geostandards easily accessible via computer. This lecture was followed by an invited presenta- tion from Jean Kane (NIST) who highlighted the growing impact of ICP-MS in certifying geochemical reference materials. The remainder of Monday morning concentrated on the preparation of natural and synthetic reference materials for laboratory use. A particularly interesting lecture was given by Dr. David Cohen from the University of New South Wales, Australia.Dr. Cohen reported on the development of customized synthetic standards with the aim of reducing possible inhomogeneities that could potentially occur in natural geochemical reference materials. Following a buffet lunch, the afternoon speakers empha- sized the need for international cooperation in quality control. Invited lectures were given by Dr. Michael Thompson (University of London), and also by Dr. Chris Riddle (Management Board Secretariat, Canada) who presented a Canadian perspective. Further presentations were concerned with laboratory programs to ensure reliability and accuracy of data produced. Professor R. K. O’Nions of the University of Cambridge presented the final plenary lecture of the day on ‘High Resolution SIMS Instrumentation in the Earth Sciences’.A varied poster display was also available for viewing throughout the day. On Monday evening, an informal drinks gathering was followed by dinner and an opportunity to attend a workshop on a potential Gcoanalytical Accreditation Program led by Dr. Riddle. As an alternative, a midnight bar extension, along with the close proximity of Ambleside allowed an enjoyable end to the day. Tuesday’s first plenary lecture was given by Dr. G. Remond of BRGM, Orleans, who discussed the advantages and limitations of layered and ion-implanted specimens as possible reference materials to calibrate analytical instruments. The lecture program was then streamed to accommodate presenta- tions concerning neutron activation analysis and ion and electron probe techniques.The ion and electron probe stream chaired by Drs. Stephen Reeder (BGS) and Richard Hinton (University of Edinburgh) presented academic research as well as highlighting the commercial applicability of such techniques. Dr. Susan Parry (Imperial College Reactor Centre) and Professor Eiliv Steinnes (University of Trond- heim) chaired the neutron activation stream, which included a presentation by Peter Bode of Delft University of Technology describing a developed INAA method that allows multi- element analysis of samples as large as 100 cm in length and 15 cm in diameter. Professor Peter Vaganov of St. Petersburg University illustrated the use of INAA in the study of Conference delegates outside British Nuclear Fuel’s reprocessing plant at Sellafield.The Conference Dinner at Merewood Coiintr)l House. Clockwise from left: Dr. K. Gorindarajrr, Dr. J . M . Richardson, Dr. P. J. Potts, Ms. G. E. Hall, Mr. D. L. Miles, Dr. C . Riddle and Ms. J . M. Cook. * Geoanalysis 94 Special Issue of The Atzalyst will be published in May 1995.52N Analyst, April 1995, Vol. 120 combustion products from power plants in China and Estonia. On an environmental note, Dr. Marina Frontasyeva (Frank Laboratory of Neutron Physics, Russia) highlighted the role of INAA in the study of mosses, which have been used to study changes in the atmospheric deposition of metals around an iron smelter complex in Northern Norway. In the afternoon, Professor Iain Thornton (University of London) presented a well-received lecture concerning chal- lenges to the analyst in the assessment of contaminated land.The environmental theme was continued throughout the afternoon in the first stream of lectures which focused on the role of geochemical analysis in pollutant studies of soils and waters. Professor Xuejing Xie (IGGE, China) presented a lecture on the analytical requirements for international geochemical mapping, and this was complemented by an open discussion of the subject later in the evening. The parallel session on ICP-MS, chaired by Dr. Kym Jarvis (Imperial College at Silwood Park) and Jenny Cook (BGS), highlighted the excellent sensitivity and accuracy of ICP-MS in the study of minor and trace elements including gold, the PGEs, yttrium, boron and the REEs. Again, a variety of research posters and commercial displays complemented the day’s lectures.Wednesday’s plenary lecture, given by Gwendy Hall of the Geological Survey of Canada, gave a comprehensive review of the GSC’s research into the analysis of natural background levels of elements where detection limits must be in the range of ppb or ppt. As an example, the research has shown that terbium and other REEs in the lakes of Baie d’Espoir, Newfoundland, clearly delineate the bedrock geology, even at low ppt concentrations. The first stream of lectures on Wednesday morning centred on exploration and waters. Presentations were wide ranging, including Angela Giblin’s (CSIRO-DEM, Australia) lecture on the use of high quality groundwater analysis in the detection of concealed ore deposits to a presentation discussing trace metal analysis in oils and source rocks given by S.Olsen of Rogaland Research, Stavanger, Norway. A simultaneous stream on laser ablation ICP-MS included presentations on the use of this technique in the analysis of minerals, biologically derived materials and tree ring profiles. Wednesday afternoon was devoted to recreational activities and arrangements had been made for 30 delegates to visit British Nuclear Fuel’s reprocessing plant at Sellafield. For the remaining delegates, fine sunny weather provided excellent conditions for an organized boat trip on Lake Windermere, or to explore the scenic surroundings. In the evening, the conference dinner was held at the Merewood Country House Hotel, close to the lake, with views of the Cumbrian Mountains.A relaxed sherry reception allowed delegates to socialize before an excellent dinner. A return to the confer- ence centre was made at around midnight where drinks continued to flow well into the early hours, accounting for a few absences at Thursday’s breakfast! The final day of the conference was opened with a plenary lecture by Professor Klaus Heumann of the University of Regensburg, Germany, entitled ‘Developments in Thermal Ionization Techniques for Isotope Analysis’. The lecture programme was then split to allow streams on isotope geochemistry and X-ray fluorescence. The isotope geoche- mistry stream was varied and included presentations highlight- ing the latest isotopic analytical developments and their applications. Similarly, the XRF stream presented a broad range of research and applications. Lecture topics included the analysis of water treatment plant sludges, given by Margaret West of Sheffield Hallam University, and XRF analysis of environmental Pb by Dr. Jacques Renault of the New Mexico Bureau of Mines and Mineral Resources. The closing afternoon was dedicated to innovations in analytical developments, whilst the poster programme centred on exploration and geochemical techniques. The conference was officialy closed after these presentations although the programme continued into Friday with a Lake District field trip and a workshop on geological reference materials. Geoanalysis 94 brought together a wide range of scientists from national geological surveys, research institutes, commer- cial operators and universities. The organising committee are to be praised in succeeding in making Geoanalysis 94 a truly international conference. Robert Adkins Department of Geology Royal Holloway, University of London

ISSN:0003-2654    

DOI:10.1039/AN995200051N

出版商:RSC    

年代:1995

数据来源: RSC

摘要:

Analyst, April 1995, Vol. 120 53N The Royal Society of Chemistry Library can usually supply copies of cited articles. For further details contact: The Library, Royal Society of Chemistry, Burlington House, Piccadilly, London W1V OBN, UK. Tel: +44 (0)171-437 8656. Fax: +44 (0)171-287 9798. Telecom Gold 84: BUR210. Electronic Mailbox (Internet) LIBRARY@RSC.ORG. If the material is not available from the Society’s Library, the staff will be pleased to advise on its availability from other sources. 1 Please note that copies are not available from the RSC at Thomas Graham House, Cambridge. Future Issues will lnclude- Modified Method for the Analysis of Anionic Surfactants as Methylene Blue Active Substances-Steven K. Dentel, Srinivasarao Chitikela and Herbert E. Allen Simultaneous Determination of Organic Acids, Inorganic Anions and Cations in Beverages by Ion Chromatography With a Mixed-bed Stationary Phase of Anion-exchanger and Cation-exchanger-Ming-Yu Ding, Yoshihito Suzuki and Hitoshi Koizumi Continuous and Flow-Injection Potentiometry of Complex- Bonded Metal Ions by the Standard Addition Method-Ivelin Rizov and Liliana Ilcheva Reversed-phase High-performacne Liquid Chromatography Separation of Titanium, Vanadium, Niobium and Tantalum Ternary Complexes with Hydrogen Peroxide and 2-(5-Bromo- 2-pyriylazo)-5-diethylaminophenol. Determination of Titan- ium, Vanadium and Tantalum in Real Samples-Slawomir Oswaldowski Photoluminescence of Pyrenebutyric acid Incorporated Into Silicone Film as a Structural Probe and its Applciation for Luminescent Oxygen Sensor-Masao Kaneko and Toru Ishiji Improved Detection Limits for Transient Signal Analysis of Fluid Inclusions by Inductively Coupled Plasma Atomic Emission Spectrometry Using Correlated Background Cor- rection-M.H. Ramsey, Barry J. Coles, Sarah Gleeson and Jamie J. Wilkinson Measurement of Boron Isotope ratios in Groundwater Studies-N. C. Porteous, J. N. Walsh and Kym E. Jarvis Flow Injection Based Renewable Fibre Optic Sensor Principle and Validation on Colorimetry of Chromium(v1)-Jaromir RhZiEka and Oleg Egorov Prediction of Some Physico-Chemical Parameters in Red Wines From Ultraviolet-visible Spectrum Using a Partial Least-Squares Model in Latent Variables-Carmen Garcia- Jares and Bernard Medina Thermal Lens Spectrometry-R. D. Snook and R.D. Lowe Estimation of Uncertainty in Multivariate Vibrational Spec- troscopy-S. J. Haswell, Allison J. Hardy, Wolfhard Wegsc- heider and Perry A. Hailey Using Instrumental Techniques to Increase the Accuracy of Classical Analyses. Part 1. The Gravimetric Determination of Sulfate-Thomas W. Vetter, Kenneth W. Pratt, G. C. Turk, Charles M. Beck and Therese A. Butler Determination of Platinum in Human Blood by Using Inductively Coupled Plasma Atomic Emission Spectrometry With Ultrasonic Nebulizer-Vito Di Noto, Dan Ni, Lisa Dalla Via, Fabio Scomazzon, Maria Viviani, Francesca Bortolozzo and Maurizo Vidali Determination of Iodine Concentrations in Human Milk, Cow’s Milk and Infant Formula-I. G. Gokmen and G. Dagli Prototype, Solid-phase, Glucose Biosensor-Markas A.T. Gilmartin, John P. Hart and David T. Patton Determination of Tributyltin and Triphenyltin Compounds in Hair Using Hydrolysis Technique and Gas Chromatography With Flame Photometric Detection-Makoto Nagase, Hiro- yuki Kondo and Kiyoshi Hasebe Quantatitive Analysis of 2,6-Ditertiarybutyl-4-methylphenol (Butylated-Hydroxytoluene, BHT) Antioxidant in a Solvent- formulated Liquid Polychloroprene Adhesive and in Cured Pol ych I oropre ne Adhesive Fi 1 m s-Robert A. Franich, Hank W. Kroese and Gerry Lane Complexometric Determination of Thallium(Ii1) Using Sodium Sulfite as a Selective Releasing Agent-B. Narayana, C. H. Raghavan Nambiar, B. Uralidhara Rao and Biju Mathew Design and Characterization of Sodium-Selective Optode Membranes Based on Lipophilic Tetraester of Calix[4]arene -Wing Hong Chan, Albert W.M. Lee, Ching Man Lee, Kei Wang Yau and Kemin Wang Penzothiazole Derivatives as Substrates for Alkaline Phosp- hatase Assay with Fluorescence and Chemiluminescence Detection-Kazumi Sasamoto, Gang Deng, Tamano Ushi- jima, Yosuke Ohkura and Keiyu Ueno Analysis of Pharmaceutical Preparations Containing Cate- cholamines by Micellar Liquid Chromatography with Spectro- photometric Detection-R. M. Villanueva Camanas, J. M. Sanchis Mallols, J. R. Torres Lapasio and G. Ramis-Ramos Determination of the Concentrations of the Steroids Estrad- iol, Progesterone and Testosterone in Bovine Sera: Compari- son of Commercial DELFIA Kits with Conventional Radio- and Enzyme-Immunoassays-C. T. Elliott, Kathryn s. Francis, Hugh D. Shortt and William J. McCaughey Spectrophotometric Determination of Anionic Surfactants in Seawater Based on Ion-pair Extraction with Bis[2-(5-trifluo- romethyl-2-pyridylazo)-5-diethylaminophenolato] Coba1t(111) as Counter Ion-Issei Kasahara, Kanae Hashimoto, Tomoko Kawabe, Akiko Kunita, Keiji Magawa, Noriko Hatta, Shigeru Taguchi and Katsumi Goto Utilization of Thermal Decomposition of Immobilized Com- pounds for the Generation of Gaseous Standard Mixtures Used in the Calibration of Gas Analysers-Jacek Namiesnik, Piotr Komeczka, Andrej Przyjazny, Elzbieta Luboch and Jan F. Biernat Edible Fats and Oils Reference Materials for Sterol Analysis With Particular Attention to Cholesterol. Part 2. Certification of Sterols Mass Fraction-G. Lognay, John Pearse, W. Dennis Pocklington, A. Boenke, Barbel Schurer and Peter J. Wagstaffe COPIES OF CITED ARTICLES

ISSN:0003-2654    

DOI:10.1039/AN995200053N

出版商:RSC    

年代:1995

数据来源: RSC

摘要:

54N Analyst. April 199.5, Vol. 120 Technical Abbreviations and Acronyms The presence of an abbreviation or acronym in this list should NOT be read as a recommendation for its use. However those defined here. need not be defined in the text of your manuscript. AAS ac AID ADC ANOVA AOAC ASTM bP BSA BSI CEN cPm CMOS c.m.c. CRM CVAAS C.W. CZE dc DRIFT dPm DELFIA DNA EDTA ELISA emf ETAAS EXAFS EPA FAAS FAB FAO-WHO FIR FT FPLC FPD GC GLC HGAAS HPLC ICP id INAA IR ISFET iv im IGFET ISE LC LED LOD atomic absorption spectrometry alternating current analogue-to-digital analogue-to-digital converter analysis of variance Association of Official Analytical Chemists American Society for Testing and Materials boiling point bovine serum albumin British Standards Ins ti tuti an European Committee for Standardization counts per minute complementary metal oxide silicon critical micellization concentration certified reference material cold vapour atomic absorption spectrometry continuous wave capillary zone electrophoresis direct current disintegrations per minute diffuse reflectance infrared Fourier transform spectroscopy dissociation enhanced lanthanide fluorescence immunoassay deoxyribose nucleic acid ethylenediaminetetraacetic acid enzyme linked immunosorbent electromotive force electrothermal atomic absorption spectrometry extended X-ray absorption fine structure spectroscopy Environmental Protection Agency flame atomic absorption fast atom bombardment Food and Agriculture Organization, far-infrared Fourier transform fast protein liquid chromatography flame photometric detector gas chromatography gas-liquid chromatography hydride generation atomic absorption spectroscopy high-performance liquid chromatography inductively coupled plasma internal diameter instrumental neutron activation infrared ion-selective field effect transistor intravenous intramuscular insulated gate field effect transistor ion-selective electrode liquid chromatography light emitting diode 1 i m i t of determination assay spectrometry World Health Organization analysis LOQ mP MRL mRNA MS NIR NMR NIST od OES PBS PCB PAH PGE PIXE PPt PPb PP" PTFE PVC PDVB QC QA REE rf RIMS rms rPm RNA SCE SE SEM SIMS SIMCA SRM STM STP TIMS TLC TOF TGA TMS tris TRIS uv UV/VIS VDU XRD XRF YAG Commonly Used Symbols M r M,.S U limit of quantification melting point maximum residue limit messenger ribonucleic acid mass spectrometry near-infrared nuclear magnetic resonance National Institute of Standards and Technology outer diameter optical emission spectrometry phosphate buffered saline polychlorinated biphenyl polycyclic aromatic hydrocarbon platinum group element particle/proton-induced X-ray parts per trillion (1012; pg g-l) parts per billion (109; ng g-') parts per million (106; pg g- ) poly( tetrafluoroethylene) poly(viny1 chloride) poly( divinyl benzene) quality control quality assurance rare earth element radiofrequency resonance -i onization mass spectrometry root mean square revolutions per minute ribonucleic acid saturated calomel (reference) electrode standard error scanning/surface (reflection) secondary-ion mass spectrometry soft independent modelling of class analogy, statistical isolinear multicategory analysis emission electron microscopy Standard Reference Material scanning tunnelling (electron) standard temperature and pressure thermal ionization mass thin-layer chromatography time-of-flight thermogravimetric analysis trime th ylsilane 2- amino-2-( hydroxyme t hy1)- tris( hydroxymethy1)methylamine ultraviolet ultraviole t-visible visual display unit X-ray diffraction X-ray fluorescence yttrium aluminium garnet microscopy spectrometry propane-l,3-diol molecular mass relative molecular mass correlation coefficient standard deviation atomic mass

ISSN:0003-2654    

DOI:10.1039/AN995200054N

出版商:RSC    

年代:1995

数据来源: RSC

摘要:

Analyst, April 1995, Vol. 120 985 Routine Analytical Fourier Transform Raman Spectroscopy Part 2.* An Updated Review Patrick J. Hendra, Heather M. M. Wilson, Peter J. Wallen, Ian J. Wesley, Philip A. Bentley, Morella Arruebarrena-Baez, James A. Haigh, Paul A. Evans, Christopher D. Dyer, Ralph Lehnert and Martin V. Pellow-Jarman Department of Chemistry, University of Southampton, High field, -- _. UKSOl71BJ This paper provides an update on an earlier paper published in 1989 and summarizes the contemporary value of Fourier transform (FT) Raman spectroscopy as an analytical tool. In particular the value of sample heating and cooling, the uses of the technique in the fields of polymer characterization, pharmaceutical analysis and biochemical identification are highlighted. Fourier transform Raman studies on surfaces, gases and in inorganic systems are also discussed.The review concludes with a critical consideration of the use of alternative wavelengths to 1064 nm (that of the neodymium yttrium aluminium garnet laser) in the future development of the field. Keywords: Fourier transform Raman spectroscopy; near-infrared; design; sampling; application; review Introduction In 1986 Chase and Hirschfeldl demonstrated the feasibility of using a near-infrared laser as a source for Raman spectroscopy by collecting the scattered radiation and analysing it using a modified Fourier transform infrared (FTIR) spectrometer. Since the original paper appeared a considerable body of literature has developed describing instrumental develop- ments, the production of combined IR-Raman spectrometric systems and a bewildering range of applications of the technique to chemistry, physics, materials and biological sciences.Progress has been summarized in a recent book2 whilst an annual update is provided in the spectroscopic journal, Spectrochimica Acta.3,4,5,6 In 1989 we prepared a short review paper for the Analyst showing how the near- infrared (NIR)-FT technique had successfully lifted Raman methods from the research environment into the routine analytical laboratory.7 The burthen of the message was that: (i) Raman scattering, the ‘other half‘ of vibrational spectro- scopy to IR, is now easy to use, rapid, versatile and works in the vast majority of cases providing new qualitative and quantitative analytical opportunities. (ii) The combination of speed, ease of sampling and feasibility makes the cost per analysis highly competitive, and further, as the sample areas are interlocked with the laser source, the instruments operate in complete safety.(iii) A range of applications including the determination of unsaturation in natural oils, studies on natural rubber and its vulcanization and the identification of forensic drugs were surveyed to demonstrate the new found versatility. In this paper, we offer an ‘update’ in which we elaborate on the improvements in the already highly developed versatility of * For Part 1, see ref. 7. Southampton, the methods that have appeared recently and survey some of the latest applications to be announced. Experimental All the leading manufacturers of FTIR instruments now offer ‘Raman accessories’ enabling users to record both the IR and the Raman spectrum on the same instrument and to present both on the visual display unit and hard copy output.As a result, comparisons of both spectra are simple and analytical deductions can be made as appropriate. An example of the approach is given in Fig. 1. The instruments used at Southampton to record the spectra given in this paper are a peculiar ‘hotch potch’ of a rather old prototype based on a model 1720 combined FTIR-Raman (modified to operate in the NIR), a commercial Model 1760 ETIR instrument and a Model 2000 FTIR-Raman instrument, all manufactured by Perkin-Elmer (Norwalk, CT, USA). A very wide range of accessories have been developed at Southampton enabling spectra to be recorded at both low and high temperatures of liquids, solids and gases, of electrochem- ical systems studied in situ, of catalysts, films and of fibres.In all instances the cells can be rapidly inserted into the sample areas of any of the spectrometers and used with the sample area lids closed and hence in complete safety. All our spectrometers carry 2 in x 3 in IR style holders in the sample areas and cells are built on metal cards and slotted into the instrument. Although far from precise, location is perfectly I 1 I I 1 I I 3500 3000 2500 2000 1500 lo00 500 Wavenumbedcm-’ Fig. 1 phenone. A, Infrared and B, Raman spectra of 2.5-dichloroaceto-986 Analyst, April 1995, Vol. 120 > c .- E adequate and no alignment between sample changes is required.Several of the cells are described below as we outline a range of applications of FT Raman spectroscopy to analytical chemistry. j u C I Polymers One of the most rapidly growing areas of analysis and research where vibrational spectroscopy has a major role is in the polymer industry. Although in classical organic chemistry infrared has 'lost out' to nuclear magnetic resonance (NMR), the versatility of IR has kept it in a prime analytical position. Fourier transform Raman is as versatile and has the further advantage that sampling is much less demanding. Thus, it is routine to record spectra of lumps or fibres, films or coatings, melts or solutions provided a sufficient depth of sample is available. If the material is oriented, then depending on the nature of the orientation (cylindrical or three dimensional) Raman methods can be used to measure the degree of orientation.Clearly, there is not room here to describe in detail all the applications that have appeared, but readers may wish to consult a brief review on synthetic polymer characteri- zation8 and another on the analysis of elastomers.9 Recently a book has appeared in this field.10 Four applications have been selected here, to illustrate significant points. Polymerization and Crosslinking Polymerization reactions and their inverse, degradation of materials in service, have been described but the field considered here in detail is the vulcanization of natural and synthetic rubbers. Rubber is vulcanized almost exclusively with sulfur and the reaction, accelerated with the appropriate additives, is normally carried out at approximately 150 "C.It is simple to devise a heated Raman cell suitable for us in an NIR excited FT machine. The cell is very simple in design, as shown in Fig. 2. The main body consists of an aluminium block that is mounted centrally on the standard 2 in x 3 in IR card. A small heating element is incorporated into the end of the block and a thermocouple is mounted in the top just behind the sample position. The samples for analysis can either be placed in a standard test-tube if they are powders or liquids, or in a metal inset fitted into the sample hole if they are in solid form. The temperature and heating rate are controlled using a CAL 9000 thermostatic unit. Using this cell, temperatures of over 200 "C can be achieved, but it must be noted that at these temperatures the region of the spectrum above 2000 cm-* is obscured by the intense blackbody background.Although the temperature range is restricted, it has been possible to follow the complex reactions that occur during the sulfur accelerated vulcanization of unsaturated rubbers in situ. This is particularly advantageous because some of the species thought to form during the process are unstable and would no longer be present if the sample was allowed to cool to room Thermocouple /position Heating element Laser directi Fig. 2 Diagram of a hot cell. temperature prior to analysis. In the first series of experiments reported, the interaction between the vulcanization agents sulfur, zinc oxide and the accelerator mercaptobenzothiazole (MBT) was explored in an inert medium.The Raman spectrum of a ZnO-MBT-S mixture ( 5 + 2 + 4 m/m/m) in liquid paraffin heated to the vulcanization temperature of 150°C is shown in Fig. 3, €3. A number of changes in the spectrum are apparent when it is compared with that recorded at room temperature (Fig. 3, A). Two separate processes were identified. (i) When crystalline sulfur is melted, the normally intense bands near 470 and 220 cm-1 are reduced in intensity. Using their presence or absence as evidence, the solubility of sulfur versus temperature in both natural rubber and ethylene propylene diene monomer (EPDM) has been assessed. (ii) Formation of a Zn-MBT complex by a solid-liquid phase acid-base reaction accounting for the changes in the region 1600-600 cm-1, at temperatures around 60°C.On cooling back to room temperature and re-recording the spectrum the reaction was predictably found to be non- reversible. The hot cell was also used to investigate the reactions occurring when heating a mixture of MBT-S (1 + 4). These results showed some interesting changes that occur to the thiazole as shown in Fig. 4. MBT is known to exist as two tautomers, the thione and the thiol. At room temperature the thione form is preferred, whereas at higher temperatures MBT adopts the thiol form. From the spectra recorded at elevated temperatures it is clear that there is partial, but by no means complete, conversion to the thiol form. At present it is not clear if these changes are caused by the action of heat alone or the solution of MBT in molten sulfur or a combination of both processes.However, on cooling back to room temperature and re-recording the spectrum, the sample found to be identical to the initial one, indicating a reversible process. Clearly, the reactions described above, although relevant to rubber chemistry are really inorganic in nature. When mixed 1600 1400 1200 1000 800 600 400 200 Raman shiftkm-' Fig. 3 Raman spectra of a ZnO-MBT-S mixture in liquid paraffin at A, room temperature and B, 150 "C. AddL-,*iA __ _______ A * ji_ I I I I I I I 1600 1400 1200 1000 800 600 400 200 Raman shifvcm-' Fig. 4 Raman spectra of an MBT-S mixture at A, room tempera- ture, B, 150 "C and C, as in B but cooled back to room temperature.Analyst, April 1995, Vol.120 987 with the rubber and heated the bands near 1680 cm-1 owing to YC=C in cis-polyisoprene develop lower frequency shoulders; unquestionably due to re-isomerization, ring formation and other perturbations of the crosslinking process. Further, as the reaction proceeds bands owing to the sulfur disappear. This field is being investigated using FT methods and extended to synthetic rubbers such as polybutadiene or ethylene propylene diene tercopolymers. In all instances, FT Raman is of unique value because, unlike its visible relative, NIR method is free from fluorescence. As mentioned above, there is a severe restriction in the temperature to which samples may be heated before the black body emissions 'swamp' the Raman bands. This is a serious problem because so many polymers melt or undergo phase changes or reactions above 200 "C.There are, however, ways of reducing the nuisance of blackbody backgrounds. The vibrational spectrum of a polymer melt usually differs markedly from those of the crystalline or partially crystalline materials. This is owing to the larger number of molecular conformations present in the molten state and also a break- down of the crystal and molecular symmetry. The spectro- scopic selection rules can then cause 'crystalline' bands to disappear, new bands to appear and also existing bands to widen and become diffuse. An example of a polymer that shows different behaviour is shown in Fig. 5 where the Raman spectrum of poly(tetrafluoroethy1ene) (PTFE) at 36 "C is compared with that recorded at 380 "C.It has been noted above that using the conventional laser for FT Raman spectroscopy [neodymium yttrium aluminium garnet (Nd: YAG) operating C.W. at 1064 pm] it is impossible to record adequate spectra at temperatures much above 20 "C due to blackbody emission. The spectrum of PTFE recorded at 380 "C was obtained using two spectroscopic ruses. (i) The laser source wavelength was reduced to 780 nm moving the whole spectrum towards the visible and hence reducing the nuisance of blackbody emission. (ii) A cut-off filter was incorporated after the sample to reduce the emission still further. The laser filter used in this experiment was of modest quality, hence radiation was detectable only above Av = 500 cm-1, but it did serve to allow us to explore some of the differences that occur when a high melting polymer is fused.In the frequency range that could be investigated none of the bands present in the spectrum of the crystalline material disappeared in Fig. 5 , the only major change in the spectrum Raman shiftkm-' Fig. 5 Raman swctra of PTFE at (u) 36 and ( h ) 380 "c'. being a slight softcning of the frequencies and ii marked band broadening . The vibrational behaviour of PTFE is that of a helix of severity 6 turns in a chain of 13 CF,s or 7 in 15 depending on temperature. The vibrational modes of a non-helical rando- mized chain of CF2s would be very different and give rise to broad, diffuse IR or Raman spcctra. Exactly this bchaviour is found in polyethylene, which o n melting randomizes from a planar zig-zag structure.The minor changes in the PTFE spectrum on melting requires that the helical structure persists over lengths of several rotation5 (probably = C2()). Citation5 to this reasoning based on studies on oligomers of PTFE are given in refs. 11 and 12 The use of Raman methods to measure the degree of crystallinity in solid PTFE specimens and to do so rapidly and reliably has been reported very recently. 13 Effect of Stress Stretching polymer specimens can have two profound effects: crystalline materials may reorganize themselves into oriented fibrillar morphologies and do so in an isothermally irreversible manner (e.g., the production of high tenacity fibre and film). Rubbers kept well above their 'glass transition' temperatures undergo orientation and even cryqtallization when stretched and the relaxation and melting processes are partially revers- ible.Several accounts are now available describing stress- induced (and thermally-induced) crystallization in natural rubber. It seems that the Raman evidence conforms to what is already known; that on straining to >400% oriented crystal- lites form with a morphology identical to those found when rubber is kept at around - 10 "C for long periods.13.14 Natural rubber is not the only elastomer to behave in this way. Recently we have investigated the stress-induced crystalli- zation in cross-linked poly(isobuty1ene) (PIB) using FT Raman methods. Rubber-like polymers can be stressed to yield oriented, or in some instances, even oriented crystallized materials, above their glass transition temperatures. PIB is a common example of an elastomer that is known to show such behaviour when stretched.Vibrational spectroscopy has already been used to investigate stress-induced crystallization in this polymer, but most work has been carried out using IR, the information presented here was obtained using FT Raman spectroscopy. The spectra shown in Fig. 6 are of butyl rubber (unstretched and stretched = ~ 1 0 ) . The huge differences between the spectra are surprising, the bands at 725 and 810 cm-i being caused by stress-induced crystallization. It is, however, worth mentioning that natural rubber also changes its Raman characteristics markedly when it crystallizes. As carried out in an FT Ranian accessory, all measurements contain an anisotropic element because the laser is polarized. If the sample is isotropic and no polarization analyser is incorporated into the optical train, the spectrum collected can be assumed to contain no anisotropic information.If an analyser is incorporated, two spectra are available, one where the analyser and laser sector are parallel((, the other where they are perpendicular I. The intensity 1 , /I 11 can be highly informative in assigning bands to fundamental modes and all textbooks cover this subject.' It' the sample is anisotropic further series of spectra become possible. Thus in the presented example of stretched rubbers the laser can be polarized 1) and I to the stretch direction and again the scattered light can be analysed. In crystalq six cxperimcnts are possible.Thc details of the analysis of thcce spectra i n polymers and/or their use in defining dcgrees of orientation are given in in ref. 9. In Fig. h the polariration of the laser and samnle orientation are indicatcd.988 Analyst, April 1995, Vol. 120 Use of Low Temperature Sampling One of the restrictions involved in FT Raman spectroscopy is that the NIR laser radiation is absorbed to some extent and the sample heats. In the vast majority of situations the tempera- ture rise is small (e.g.7 < 20 "C) and the problem non-existent. In others, the temperature rise can be significant. I n these instances the use of a low temperature cell is highly desirable and such a cell has been devised that is compact enough to fit inside the closed sample area of the spectrometer.It is of the transfer gas type and made entirely of glass. The Dewar vessel is sealed and no external connection is required. Temperature can be monitored with a thermocouple passed down central sample supporting tube to the aluminium sample holder. Apart from the avoidance of destructive sample heating, cooling a sample can be very beneficial as the bands narrow and hence increase in height. However, a word of caution: if the morphology changes as the sample cools, spectral changes are to be expected. To demonstrate the point about the spectral quality, Fig. 7 shows a spectrum of semicrystalline polystyrene recorded at room temperature and at - 130 "C. There are dramatic differences between these spectra, par- ticularly noticeable is the splitting of the band at 1000 cm-'.The band profile is related to the degree of crystallinity of the polystyrene and a report on the subject has recently been published. 15 Gases No one interested in gas analysis and deciding upon Raman methods would use an FT Raman instrument from choice. The ability to identify quantitatively homopolar diatomics is attractive but conventional Raman spectroscopy with its inherent simplicity and sensitivity is perfectly feasible in these situations. Fourier transform Raman methods are an 'over- kill': fluorescence is not a problem here. However, analysts equipped with FT instruments are likely to be asked to do their best with what they have. We have devised a special gas cell and recently demonstrated its value.16 The cell consists of a long tube of glass (1.4 mm id) and gold-coated down the bore.The tube is mounted into the spectrometer in the normal sample position with the laser projected down its centre. Raman radiation is multiply reflected back along the tube and into the collection lens. An example of the spectra that can be obtained is shown in Fig. 8. Surfaces Fourier transform Raman methods have already found a place in surface science. Several accounts have appeared where 5.0 1- -0.00 I II I I I I 4000 3000 2000 1600 1200 800 400 Raman shiftlcm-' Fig. 6 Raman spectra of butyl rubber: ( N ) unstrctched and ( h ) stretchcd X 10. Extension direction horizontal. laser polarization vertical. pyridine has been sorbed onto zeolite and other oxide surfaces, the Raman spectra being used to characterize the surface acidic sites, i.e., to quantify the proportion of Bronsted, Lewis and H-bonded ~ites.1~9~8 It is also feasible to examine and characterize changes that occur in oxides as they are treated with a variety of reagents. One such change concerns the hydration of gamma alumina, a project invohing cooperation between ourselves and the University of Luleii in Northern Sweden. The remarkable ease with which the hydrated surface may be characterized as bayeritic AI(OH)3 using near-infrared FT Raman is noteworthylg; the latest results20 show that the adsorption of phenylphosphate anion onto the gamma alumina surface prior to hydration blocks the reaction almost completely.Only the harshest hydration conditions produce a little bayerite. The two spectra shown in Fig.9 demonstrate the blocking effect on the surface layer transformation. Surface Enhanced Raman Scattering Fourier transform Raman methods have also been applied to electrochemical cells in situ. It has been known for many years that illumination of copper, silver and gold surfaces electro- chemically roughened in a cell produces a great enhancement of the Raman spectrum of species adsorbed and/or coordi- nated to the metal surface, i.e., the spectrum observed originates in a monolayer in the electrical double layer.21 It is 1250 1 200 1150 1100 1000 950 Raman shiftlcm-' Fig. 7 and B, room temperature. Raman spectra of semicrystalline polystyrene at A, -130 "C 1400 1200 1000 800 600 400 200 Raman shift/cm-' Raman spectra of ( a ) H2 and ( b ) D2 at 1 atm.Fig. 8Analyst, April 1995, Vol. 120 989 now clear that this type of spectroscopy [the technique is called surface enhanced Raman scattering (SERS)] can be carried out using NIR excitation, and, with remarkable speed and convenience, using the FT approach,z2 thus providing the potential for rapid ultra-sensitive analysis. Confining SERS activity to Cu, Ag and Au is obviously a severe limitation. One of several available techniques to extend the scope of the method is to coat the non-active metal surface with colloidal silver and then to lay the adsorbate onto the ‘sandwich’. Fig. 10 shows the spectrum of the corrosion inhibitor MBT adsorbed onto smooth, and hence inactive, copper foil using 780 nm excitation. The SERS enhancement is provided by concentrated silver colloid deposited onto the smooth metal substrate.The term ‘smooth’ is used to indicate an unroughened metal surface which showed no sign of SERS enhancement without the addition of the silver colloid. Details of the preparation of the colloid and foil are given in a published account.23 By using this technique it should be possible to identify the presence of trace organics on other non-SERS active substrates. However, it is important to note that the MBT is not a free uncomplexed state on the copper surface making this kind of technique especially valuable in corrosion studies. Inorganic Compounds In some respects NIR FT Raman methods have been disappointing in inorganic chemistry because in many instances absorption occurs or fluorescence is excited by the 200 ,-?!I i I 160 2- u) al c .- c.3700.0 3000 2000.0 1600 1200 800 400 150.0 Raman shift/cm-’ Fig. 9 phosphate and (b) hydrated without phenylphosphate. Raman spectra of gamma A1203 (u) hydrated with phenyl- lr” v1 1 I I I I I 1600 1400 1200 1000 800 600 400.0 Raman shift/cm-’ Fig. 10 colloid. Raman spectrum of copper foil treated with MBT and silver Nd:YAG laser. The situation has been reviewed.24 In some instances the NIR laser is particularly appropriate, e.g., in situations where photosensitivity is a problem, such as in photographic chemistry. One such application is the study of fixing solution species used in photography. In solution, the reaction occurs between thiosulfate, often the ammonium salt, and the silver halide on the photographic film, which is usually composed of a mix of bromide and iodide.The principle products are silver thiosulfate complexes but other species do occur such as the thionates. It has been possible to produce Raman spectra from the thiosulfate reactants25 and minor products such as the polythionates. (Fig. 11). A11 the advantages of FT Raman spectroscopy apply in the inorganic field; freedom from sampling convenience and lack of skill but fluorescence can be a particularly annoying problem. This situation occurs in the study of fixing solutions; spectra are obtained, but over a persistent background. To avoid these and absorption problems it is essential to have available sources other than 1064 nm; this point is addressed below. Biosamples A considerable literature is developing where biochemists are examining a wide range of species using NIR methods.These range from bones26 and eyes27 to deposits inside arteries.28 Similarly, we are just beginning to see results from systematic investigations of molecular systems, e.g., edible fats where the degree of unsaturation can be rapidly quantified29 carbohy- drate characterization,30 pharmaceutical analyses (there are several of these)3* 3 and peptides.33.34 To demonstrate just one application, NIR FT Raman spectroscopy has been shown to be very effective in the differentiation of hard and soft woods.35 The major difference in the spectra is due to the type of lignin found in the sample. Lignin is a random polymer with a complex three dimensional structure. The lignin found in hardwoods is classified as Type GS (guaiacyl-syringyl) and is believed to be formed by the free-radically initiated polymerization of the precursors trans- coniferyl and trans-sinapyl alcohols (Fig.12). Softwood lignin is classified as type G (guaiacyl) and is based almost entirely on trans-coniferyl alcohol. The spectra of beech, a typical hardwood, and spruce, a typical softwood, are shown in Fig. 13 and the spectra of their respective milled wood lignins (MWLs) are shown in Fig. 14. The spruce MWL consists of 99 mol% trans-coniferyl alcohol whilst the beech MWL consists of 33 mol% trans-coniferyl alcohol and 67 mol% trans-sinapyl alcohol. The bands which differentiate between the two whole woods are also clearly observable in the MWL spectra. Raman shift/cm-’ Fig.11 tetrathionate and C, potassium pentathionate. Raman spectra of A, sodium trithionate, B, potassium990 Analyst, April 1995, VoL. I20 Further information on the assignments of bands in the Raman spectra are discussed in greater detail in another article.”) I t is likely that Raman spectroscopy will become a useful method in several areas of bioscience particularly if sources in the ‘deep red’ arc available. Use of ‘Deep Red’ Sources for FT Raman Spectroscopy An alternative approach to Raman spectroscopy that has become popular recently is to use a spectrograph and a position sensitive detector. By far the best of the latter is the charge-coupled dcvice (CCD). This combination can offer very high sensitivity because the detector has a very high quantum efficiency and the spectrograph exploits the multi- plex” advantage. Previously, the shorter wavelength required by CCDs meant that these devices were used with blue-green sources and hence the fluorescence problem was large. However, CCDs are now available operating efficiently into the ‘far red’ (down to -830 nm) and hence the use of ‘deep red’ laser sources with these new detectors has proliferated recently37.38 and offer now perhaps best practice in current Raman technique.CH,d CH30 1 2 Fig. 12 and 2, rrans-sinapyl alcohol. Structures of the lignin precursors 1, trans-coniferyl alcohol Fig. 13 >. m a, K a, Y .- Y .- .- *- - a, oi The most popular approach is to couple the spectrograph to a microscope and to carry out the Raman experiment on the microscope stage.This in turn makes microscopic Raman spectroscopy versatile and a powerful analytical method but greater skill is, of course, needed in its use than is typical of the FT methods where speed, convenience and the routine nature of sampling are the strong points. The advantages and disadvantages that might arise from using sources shorter in wavelength than 1064 nm have been mentioned above and discussed elsewhere .39 Briefly these might be listed: 3000 2500 2000 1500 1000 Raman spectra of A, bcech wood and B, spruce wood. Raman shiftkm-’ I, 1 > m a, a, c) .- c .- .- I - a, 01 A dvan tages- that dilute aqueous solutions might become accessible. (i) Removal of water absorption leading to the possibility (ii) An increase in value in inorganic chemistry.(iii) The use of cheaper detectors lowering the cost of instruments. Disadvantages- (i) An inevitable increase in fluorescence in organic analy- tical samples. (ii) Possible increases in the incidence of laser absorption and hencc sample heating and destruction. To assay these conflicting considerations we have set up an instrument to operate at 780,835,920 and 1064 nm and a wide range of samples are being studied to quantify the advantages versus the disadvantages. On comparing the spectra of poly(pheny1ene sulfide) (PPS) and MBT excited at four wavelengths (see Figs. 15 and 16), the trends are apparent. Although the samples fluoresce using 780 and 835 nm sources moving to 920 nm yields a significant improvement. It is too early to judge the value of sources in the very near IR but preliminary results indicate that across a wide range of samples it will be inappropriate to reduce the wavelength much below 900 nm.This in turn means that low cost silicon detectors cannot be used and hence moving from the established Nd:YAG sources seems unlikely. These comments do not apply to inorganic compounds where the availability of several sources is highly desirable. Conclusions Fourier transform Raman methods have made significant strides in the analytical field since our earlier report I I I 3000 2000 1000 E 3000 2000 1000 3000 2500 2000 1500 1000 Raman shiftlcrn-’ Fig. 14 spruce. Raman spectra of milled wood lignin of A, beech and B , Raman shift/cm-’ “ Unlike ii scanning spectrometer. a spectrograph views the whole spectrum f o r t h e duration o f the euperinient.Fig. 15 835; and D, 780 nm. Raman spectra of PPS obtained using A, 1064; B , 920; C,Analyst, April 1995, Vol. 120 99 1 B 3000 2600 2200 1800 1400 1000 600 Raman shiftkm-' Fig. 16 Raman spectra of MBT obtained using A, 1064; B, 920; C, 835; and D, 780 nm. appeared? Instruments have improved applications are prol- iferating and the machines are being installed worldwide at a rapid rate. Several sources of information exist and are to be recommended including a chapter in an encyclopedia of analytical chemistry41 and as already mentioned above, an annual series of special editions of a learned journal dedicated to the technique. 1 2 3 4 5 6 7 8 9 10 References Chase, B., and Hirschfeld, T. B., Appl. Spectrosc., 1986, 40, 133.Hendra, P. J., Jones, C. H., and Warnes, G. M., Fourier Transform Raman Spectroscopy, Ellis Honvood, Chichester, 1991. Spectrochim. Acta, Part A , 1990.46 (2), 121. Spectrochim. Acta, Part A , 1991, 47 (9/10), 1133. Spectrochim. Acta, Part A , 1993,49 (5/6), 609. Spectrochim. Acta, Part A , 1994, 50 ( I l ) , 1811. Ellis, G., Hendra, P. J., Hodges, C. M., Jawhari, T., Jones, C. H., le Barazer, P., Passingham, C., Royaud, I. A. M., Sanchez BIBsquez, A., and Warnes, G. M., Analyst, 1989, 114, 1061. Edwards, H. G. M., Johnson, A. F., and Lewis, I. R., J . Raman Spectrosc., 1993, 24, 475. Maddams, W., Spectrochim. Acta, Part A , 1994, 50, 1967. Bower, D. I . , and Maddams, W. F., The Vibrational Spectro- scopy of Polymers, Cambridge University Press, Cambridge, 1989.~~ I1 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 Lyerla, J. R., and Vanderhort, D. L.. J . Am. Chem. SOC., 1976, 98, 1697. Rabolt, J. F., and Fanconi, B., Polymer, 1977, 18, 1258. Lehnert, R., and Hendra, P. J., Polymer, submitted for publication. Jackson, K. D. 0.. and Hendra, P. J . , Spectrochim. Acta, Part A , 1994, 50, 1987. Wesley, I. J., and Hendra, P. J., Spectrochim. Acta, Part A, 1994, 50, 1959. Dyer, C. D., and Hendra, P. J . , Analyst, 1992, 117, 1393. Ferwerda, R., van der Maas, J. J., and Hendra, P. J., J. Phys. Chem., 1993,97, 7331. Ferwerda, R., van der Maas, J. H., and Hendra, P. J., Vib. Spectrosc., 1944, 1, 37. Dyer, C. D., Hendra, P. J., and Forsling, W., Spectrochim. Acta, Part A , 1993, 49, 715.Dyer, C. D., Hendra, P. J . , Forsling, W., and Ranheimer, M., Spectrochim. Acta, Part A , 1993, 49, 691. Review, Surface Enhanced Raman Scattering, ed. Chang, R. K . , and Furtak, T. E., Plenum Press, New York, 1982. Angel, S. M., Katz, L. F., Archibald, D. D., Lin, L. T., and Honigs, D. E., Appl. Spectrosc., 1988,42, 1327. Wilson, H. M. M., Vib. Spectrosc., 1994, 7, 287. Almond, M. J., Yates, C. A., Horrin, R., and Rice, D. A., Spectrochim. Acta, Part A , 1990, 46, 177. Day, T. N., Hendra, P. J., Rest, A. J . , and Rowlands, A. J., Spectrochim. Acta, Part A , 1991, 47, 1251. Haigh, J. A., Hendra, P. J., Rowlands, A. J., Degen, I. A., and Newman, G. A., Spectrochim. Acta, Part A , 1993,49, 723. Nie, S . , Bergbauer, K. L., Ruck, J. F. R., and Yu. N. T., Spectroscopy, 1990, 5 , 24. Nie, S . , Bergbauer, K. L., Kuck. J. F. R., and Yu, N. T., Exp. Eye Res., 1990, 51, 619. Rava, R. P., Baraga, J. J . , and Feld, M. S., Spectrochim. Acta, Part A , 1991, 47, 509. Sadeghi-Jorabchi, H., Hendra, P. J . , Wilson, R. H., and Belton, P. S . , J. Am. Oil Chem. SOC., 1990, 67, 483. Goral, J . , and Zichy, V., Spectrochirn. Acta, Part A , 1990, 46, 253. Davis, M. C., Binns, J. S., and Melia, C. D., Spectrochim. Acta, Part A, 1990,46, 277. Cutmore, E. A., and Skett, P. W., Spectrochim. Acta, Part A , 1993, 49, 809. Gani, D., Hendra, P. J., Maddams, W. F., Passingham, C., Royaud, I. A. M., Willis, H. A., and Zachy, V., Analyst, 1990, 115, 1313. Hallmark, V., and Rabolt, J. F., Macromolecules, 1989,22,500. Evans, P. A., Spectrochirn. Acta, Part A , 1991, 47, 1441. Wienstock, I. A., Atalla, R. H., Agarwal, U. P., Minor, J. L., and Petty, C. J . , Spectrochim. Acra, Part A , 1993, 49, 819. Schulte. A., Appl. Spectrosc., 1992, 46, 891. Wang, Y., and McCreery, R., Anal. Chem., 1989, 61, 2647. Hendra, P. J., Pellow-Jarman, M., and Bennett, R., Vib. Spectrosc., 1993.5, 31 1. Hendra, P. J., Encyclopedia of Analytical Chemistry, ed. Townsend. A., Academic Press, London 1995.43994497. Paper 4103870C Received June 27, I994 Accepted October 28, 1994

ISSN:0003-2654    

DOI:10.1039/AN9952000985

出版商:RSC    

年代:1995

数据来源: RSC

摘要:

Analyst, April 1995, Vol. 120 993 Qualitative and Semi-quantitative Trace Analysis of Acidic Monoazo Dyes by Surface Enhanced Resonance Raman Scattering C. H. Munro, W. E. Smith and P. C. White* Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, GI I X L UK Resonance Raman (RR) and surface enhanced resonance Raman scattering (SERRS) procedures are described for the analysis of acidic monoazo dyes. By the comparison of the RR spectra, discrimination is achieved between 20 acidic monoazo dyes, including structural isomers. However, difficulties are experienced due to fluorescence, to the narrow concentration range over which scattering is observed (10-3-10-4 mol 1-1) and to the relatively high detection limit (approximately 3-5 pg). These difficulties were overcome by the development of a robust, sensitive and selective SERRS procedure.Controlled aggregation of a citrate-reduced silver colloid and strong SERRS of the adsorbed dyes can be obtained if a 0.01% aqueous solution of poly(~-lysine) is added to an aliquot of colloid followed by aqueous solutions of the dye and ascorbic acid. The enhancement in scattering intensity compared to solution resonance is approximately 105-106 and strong SERRS is observed for sub-nanogram amounts of dye. In addition, the fluorescence background is quenched and a wide concentration range can be examined. Models are proposed for the bonding of poly(L4ysine) with o-hydroxy-, p-hydroxy- and o-dihydroxyarylazo dyes and a single model of interaction is proposed for the adsorption of the full set of dyes on the silver surface in the presence of ascorbic acid. The results of a blind trial confirm the usefulness of SERRS for qualitative analysis and highlight the importance of sample purity.Linearity in a plot of concentration versus scattering intensity was observed at low solution concentrations (<3 x 10-6 mol I-l), supporting the application of SERRS for both qualitative and semi-quantitative analysis of trace amounts (2300-500 pg) of acidic monoazo dyes. Keywords: Surface-enhanced resonance Raman scattering; monoazo dyes Introduction Acidic dyes are used to colour a large number of materials, including food, drink, water-based paints, cosmetics, inks, leather and a range of fibres (wool, nylon, silk and modified acrylic). The discrimination of these dyes in low-concentration mixtures is an important analytical problem. For example, it is often necessary within forensic science to examine materials that have been coloured using these dyes.Simple qualitative methods such as thin-layer chromatography are generally employed to compare control and suspect dye samples. * To whom correspondence should be addressed. However, the ability to characterize the molecular structure of small amounts of dyes (typically 10 ng or less) would be highly advantageous. A high-performance liquid chromatographic (HPLC) technique that utilizes multivariate analysis of data generated from a polystyrene-divinylbenzene (PSDVB)- packed column combined with a multi-wavelength detection system is capable of providing structural information. 1 However, some difficulties are still experienced in their characterization. In particular, the discrimination between structural isomers is limited. Surface enhanced resonance Raman scattering (SERRS) has emerged as a potentially useful analytical technique for the examination, under electronic resonant conditions, of trace amounts of Raman-active compounds adsorbed on silver.2-9 The SERRS process is extremely efficient , allowing detection levels in the region of 10-~-10-11 mol I-* to be achieved.3-5 In addition, fluorescence from adsorbed species is often quenched by radiationless energy transfer to the metal surface, and this has enabled Raman spectra to be obtained for compounds for which this would normally be hindered by the presence of a strong fluorescent background.l0.11 In a recent study, a SERRS procedure was described for the analysis of acidic mono-azo dyes.12 SERRS of these com- pounds was obtained if a 0.01% solution of poly(L-lysine) was added to a citrate-reduced silver sol. Further enhancement of the SERRS intensities was obtained by the addition of ascorbic acid. Significant differences in the recorded SERR spectra were reported between dyes of different structural type, indicating that SERRS may have unique advantages for the selective determination of specific dyes at low concentra- tions in mixtures. To assess the applicability of the technique to the analysis of acidic monoazo dyes, a primary test set of 20 of these dyes was examined. This set included three main subsets of dyes; o-hydroxy-, p-hydroxy- and 0, o-dihydroxy- arylazo dyes.The dyes examined correspond to those examined by a current HPLC method.' An additional set of six unknown dyes was examined in a blind trial. Experimental Sodium citrate, silver nitrate (Johnson Matthey), ascorbic acid (Aldrich) and poly( L-lysine) hydrobromide, M , 4000- 15 000 (Sigma) were of analytical-reagent grade. The dyes used were Acid Brown 102 (CI 14615), Acid Orange 8 (CI 15575), Acid Red 88 (CI 15620), Mordant Violet 5 (CI 15670), Mordant Black 15 (CJ 15690), Mordant Black 17 (CI 15705), Acid Orange 12 (CI 15970), Food Orange 2 (CI 15980), Food Yellow 3 (CI 15985), Acid Orange 16 (CI 16011), Food Red 17 (CI 16035), Acid Red 13 (CI 16045), Acid Orange 14 (CI 16100), Mordant Red 9 (CI 16105), Acid Red 26 (CI 16150), Food Red 6 (CI 16155), Acid Red 27 (CI 16185), Acid Orange994 Analyst, April 1995, Vol.120 10 (CI 16230), Acid Red 44 (CI 16250) and Acid Red 18 (CI 16255). Dye samples were provided from the reference dye collection in the Forensic Science Unit, University of Strathclyde. Purified dye samples were obtained by preparative thin- layer chromatography (TLC). Preparative TLC plates were prepared by applying a 50% m/v aqueous slurry of Merck silica gel 60G to 100 X 200 mm glass plates at a thickness of 0.5 mm using a spreader. The plates were dried for 1 h at 110°C prior to use. The TLC solvent system used was butanol-acetone-water-ammonia ( 5 + 5 + 1 + 2 v/v). Each dye was applied individually as a line 15 mm from the long edge of the preparative plates.The plates were then deve- loped over a distance of 75 mm in a sealed, saturated TLC tank. After development, the major coloured band was scraped from the plate, extracted with methanol and filtered. The filtrate was evaporated to dryness and the purified dye dissolved in distilled water. Silver sols were prepared according to a modified Lee and Meisel method.* All glassware was rigorously cleaned before use by treatment with aqua regia [HN03-HCl (1 + 3 v/v)] followed by gentle scrubbing in a soap solution. A sample of silver nitrate (90 mg) was suspended in distilled water (500 ml) and heated rapidly to 100°C. A 1% solution of sodium citrate (10 ml) was added under vigorous stirring and the solution was kept boiling for 80 min with continuous stirring.A 50% v/v solution of the resultant silver colloid was prepared in distilled water prior to SERRS analyses. For determinations by resonance Raman spectrometry, individual solutions containing concentrations of 10-3-10-4 rnol 1-1 of each dye were prepared in distilled water. For SERRS, individual solutions containing concentrations of approximately 10-5-10-8 mol 1-1 of each dye were prepared in distilled water. To promote adsorption of the dye and controlled aggregation of the silver colloid a 0.01% aqueous solution of poly(L-lysine) (150 pl) was added to an aliquot of the silver sol (2 ml), followed by an aqueous solution of the purified dye (10-5-10-8 mol 1-1; 100 ~ 1 ) and ascorbic acid (1 mol 1-1; 150 pl). Visible absorption spectra in distilled water were recorded with a Unicam 8700 Series spectrophotometer using 10 mm quartz cuvettes.Resonance Raman spectra were recorded using a Spectra-Physics Model 2020 argon ion laser (100 mW) as the excitation source (457.9 nm), with conventional 90" geometry. The spectra were dispersed by an Anaspec-modi- fied Cary 81 scanning monochromator with a spectral resolu- tion of 4 cm-1. A cooled Thorn EM1 9658R photomultiplier tube was used for detection, with photon-counting electronics €or data acquisition. A micro-positionable quadrant cell holder was used for accurate and precise positioning of a 10 mm cuvette. Each spectrum took approximately 12 min to acquire. Results and Discussion The structures of the 20 test dyes in this study are shown together with their generic names and Colour Index (CI) numbers in Fig.1. The visible absorption spectra (400- 700 nm) of the dyes were recorded in universal buffer at pH 3, 6 and 12. The spectrum for each dye recorded in distilled water (pH 6) matched that recorded in universal buffer at pH 6. Comparison of the absorption spectra confirmed that, under the present conditions, the hydrazone form (I) is predomi- nantly adopted by these dyes. The spectra recorded at pH 6 are virtually identical with those recorded at pH 3 for all but one of the dyes [Mordant Black 15 (CI 15690)l. The absorption spectrum for this dye at pH 6 undergoes a bathochromic shift in comparison with that for pH 3. However, it was virtually identical with the absorption spectrum recorded at pH 12, thereby indicating that the azo form (11) is predominant in this case.I Hydrazone form II Azo form On examination of the remaining absorption spectra recorded at pH 12, strong hypsochromic shifts are observed for the sixteen o-hydroxyarylazo dyes, consistent with a tautomeric shift to the azo form (Ahmax = 40 nm). However, the other dyes examined do not fit this model, and bathoch- romic shifts were observed at pH 12. These dyes are the p-hydroxyarylazo dye Acid Brown 102 (CI 14615) and the o, o-dihyroxyarylazo dyes Mordant Violet 5 (CI 15670), Mordant Black 15 (CI 15690) and Mordant Black 17 (CI 15705). The bathochromic shift observed at pH 12 for Acid ' % ~ ~ ~ \ ~ m 3 a&N\Nq' AcidRed26 so; S 4 Acid Brown 102 CI 14615 CI 15980 C116150 Food Orange 2 Food Red6 Acid Orange 8 Food Yellow 3 CI 16155 CI 15575 CI 15985 Acid Red 88 CI 15620 \ .AcidOrange 16 CI I601 1 Acid Red 27 lo; CI 16185 Mordant Viokt 5 CI 15670 -- Acid Orange 10 CI 16230 Food Red 17 CI 16035 -09 olNgN\N% "gN$~% 6 1 Mordant Black 15 Acid Red 13 so; Acid Red44 CI 15690 CI 16045 CI 16250 So; Acid Red 18 Mordant Black 17 Acid Orange 14 CI 15705 CI 16100 CI 16255 Acid Orange 12 CI 15970 CI 16105 Mordant Red 9 Fig. 1 generic name and colour index (CI) numbers. Chemical structures of the 20 test dyes together with theAnalyst, April 1995, Vol. 120 995 Brown 102 (CI 14615) is consistcnt with the reported sensitivity of the tautomeric equilibrium of the 4-phenylazo-l- naphthol system to solvent and pH effects.13 These dyes are readily ionized, even by weak bases, to form a red mesomeric anion.An analogous ionization may provide an explanation for the similar behaviour of the o,o-dihydroxyarylazo dyes. At pH 9, strong bathochromic shifts are reported for the resul- tant anionic species in both the azo and hydrazone tautomeric forms, and on further ionization at pH 13 an additional bathochromic shift is observed. The fully ionized species can only exist in the azo form.14 At pH 6, the visible absorption spectra have maxima in the range 455-510 nm for all the dyes except Mordant Black 15 (CI 15690) (544 nm). The frequency of the argon ion laser line at 457.9 nm lies in the range covered by the adsorption band of the majority of the dyes in the set and was selected as the excitation source for the Raman examinations under elec- tronic resonant conditions.Mordant Black technically is pre-resonant with the incident radiation at 457.9 nm rather than resonant, but significant resonance enhancement may be expccted. Maximum resonant scattering may be achieved for some dyes owing to a coincidence of the absorbance maxima with the excitation frequency (457.9 nm) and tunable lasers could be used to maximize resonance enhancement for each dye. However, the greater frequency stability of a fixed line gives a better reference point which can be reproduced more simply and readily in other laboratories, hence a fixed excitation frequency was preferred. Resonance Raman Examination of Acidic Monoazo Dyes Resonance Raman (RR) spectra were recorded for each of the 20 dye samples in the test set. Examples of RR spectra for two structural isomers are illustrated in Fig.2. As a result of the selective enhancement of certain bands due to resonance, the observed spectra were relatively simple and well resolved at a spectrometer slit width of 4 cm-1. Strong fluorescence was seen to obscure partially the spectra of ten of the dyes (CI 14615, CI 15670, CI 15590, CI 15705, CI 15980, CI 15985, CI 16035, CI 16105, CI 16155 and CI 16230). In particular, the spectra for CI 14615, CI 15705 and CI 16155 were almost I I I I I I 1600 1400 1200 1000 800 600 400 200 Wavenumbedcm-' Fig. 2 Food Orange 2 (CI 15980) and ( b ) Food Yellow 3 (CI 15985). Resonance Raman spectra of structural isomers. Dyes: (a) entirely obscured by the underlying fluorescence. Similarities were observed in the RR spectra across the set of dyes and many of the strong resonance Raman bands appear to be common within the set of monoazo dyes (-1600, =1550, -1480, -1340, -1235 cm-I).The strongest resonance Raman bands were observed in the region of the spectra between 1100 and 1700 cm-I. These bands correspond to vibrations with significant in-plane skeletal nuclear displace- ments which vibronically couple the ground and excited electronic states (n, d). The majority of these bands are assigned to vibrations with atomic displacements predomi- nantly on the phenyl or naphthyl moieties, but the bands at -1235 and -1340 cm-1 are assigned to vibrations with atomic displacements predominantly on the bridging atoms (>C-NH-N=C<).ls The less intense bands that are observed between 200 and 1100 cm-1 correspond to out-of-plane skeletal deformations and C-H stretches and deformations. A notable feature was that, although similar, no two resonance Raman spectra were identical.Therefore, discrimination between all of the dycs in the test set, including structural isomers that differ only in the position of one or more substituents, is possible by Raman spectrometry. For most of the dyes examined, the substitiients (predomi- nantly sulfonic acid) are auxochromes and are not themseleves chromophoric. Mordant Black 15 (CI 15690) does contain a nitro group. However, this group will act principally as a strong electron-withdrawing group, resulting in both the stabilization of the azo tautomer at pH 6, which was observed only for this dye and the bathochromic shift of the azo form relative to the hydrazone.The vibrations with nuclear displacements predominantly on the substituent groups are not observed in the resonance Raman spectra and the strong similarities observed in the spectra are therefore expected for dyes that share the same chromophore. The differences that are observed are due to the effect of the substituent on specific normal vibrational modes of the chromophore, resulting in shifts in the vibrational frequencies. In addition, the influence of the auxochromes on the electronic structure of the chromophore will alter the Franck-Condon overlap and result in variations in resonance enhancement for some of the bands. Therefore, the relative intensity of each band is as useful as its vibrational frequency for the discrimination of the dyes in the test set examined, particularly for those bands common to this set.RR scattering was observed only within a narrow concentra- tion range of the aqueous dye solutions (10-4-10 -3 mol 1-1). At concentrations greater than 10-3 mol 1 - 1 the radiation was effectively absorbed by the dye and no appreciable scattering was observed. At concentrations less than 10-4 mol 1-1 the scattering was weak and the signal-to-noise ratio was low. The lower limit corresponds to a total dye quantity of approxi- mately 3-5 pg (based on 100 p1 of 10-4 mol 1-1 dye solution). SERR Scattering Examination of Acidic Monoazo Dyes The ultraviolet-visible (UVNIS) absorption spectrum of the silver sols showed maxima at approximately 404 nm, which can be associated with the dipolar surface plasmon for silver spheres with small radii ( ~ 2 0 nm) compared with the illumi- nation wavelength.Addition of an aqueous solution of each dye to the silver sol produced no aggregation or SERRS. Further, on acid aggregation (1% HN03; 35 PI) only non- anionic dyes gave good SERRS. This was attributed to poor adsorption of the anionic dye molecules to the sol particles owing to the negatively charged organic layer at the surface of the silver.16 To overcome this difficulty and to provide a more general method, poly(L-lysine) was added along with the dye. Poly(L-lysine) is a polycationic molecule for which the ability to promote cell adhesion to solid substrates has been996 Analyst, April 1995, Vol.120 reported. 17 On addition of poly(L-lysine) solution (0.01% ; 150 PI) to the silver sol immediately prior to the addition of the dyes, aggregation and intense SERRS were observed. Subse- quent addition of ascorbic acid (1 mol I-’; 150 PI) to the colloidal suspension resulted in an over-all increase in the observed SERRS intensity for the 16 o-hydroxyarylazo dyes and both an increase in scattering and strong shifts in the vibrational frequencies observed for the p-hydroxyarylazo dye, Acid Brown 102 (CI 14615), and also for the o,o- dihydroxyarylazo dyes, Mordant Violet 5 (CI 15670), Mor- dant Black 15 (CI 15690) and Mordant Black 17 (CI 15705). The SERR spectra of the acidic monoazo dyes are illustrated in Figs. 3-9 and the corresponding vibrational frequencies are listed in Table 1.The most intense bands are listed in decreasing order in parentheses. On examination of the SERRS spectra, three effects were observed. First, the fluorescence background that had par- tially obscured many of the resonance Raman spectra was no longer observed. Second, there was an over-all enhancement in scattering intensity compared with solution resonance of approximately 105-106-fold. Finally, the vibrational frequen- cies of the strongest SERR bands observed in the presence of both poly( L-lysine) and ascorbic acid coincide approximately with the strongest resonance enhanced bands for most of the dyes examined. However, close comparison of the RR and SERR data indicates a slight change in the relative intensities for many of the observed bands.Mordant Black 15 (CI 15690) was found earlier to predomi- nate in the azo form at pH 6. Therefore, the differences in the vibrational frequencies observed in the SERRS before and after the addition of ascorbic acid are rationalized by a switching of tautomeric form of the dye molecule from the azo to the hydrazone consistent with that expected for a decrease in pH. The other o,o-dihydroxylated dyes, Mordant Violet 5 (CI 15670) and Mordant Black 17 (CI 15705), were previously found to predominate in the hydrazone tautomeric form under the current pH conditions. However, the differences in the vibrational frequencies observed are also consistent with a switch from the azo form in the presence of poly(L-lysine) to the hydrazone form on the subsequent addition of ascorbic acid.Therefore , poly( L-lysine) appears to alter the tautomeric equilibrium in favour of the azo tautomer. The differences observed in the SERRS for the p-hydroxyarylazo dye Acid Brown 102 (CI 14615) before and after the addition of ascorbic acid are less marked than those observed for the 0, o-dihydrox- yarylazo dyes, but are significant enough to indicate that the addition of ascorbic acid does in some way affect the interaction of poly(L-lysine) and the dye. Effects of Poly(L-lysine) and the Subsequent Addition of Ascorbic Acid To provide a basis for understanding the action of poly(~- lysine), its interactions with the dye solutions were studied by visible absorption spectrometry and SERRS. Following this, the interaction between the poly(L-1ysine)-dye complexes and the silver surface was investigated and a model for their adsorption proposed.t > v) al C c .- .I- .- s oc CI CH, (4 I I I I I I I 1600 1400 1200 1000 800 600 400 200 Wave nu m be r/cm-’ Fig. 3 SERR spectra of poly(L-lysine)-dye complexes in the presence of ascorbic acid. Dyes: (a) Acid Brown 102 (CI 14615), ( b ) Acid Orange 8 (CI 15575) and (c) Acid Red 88 (CI 15620). $3 -0,s 1600 1400 1200 1000 800 600 400 200 Wavenumberkm-’ Fig. 4 SERR spectra of poly(L-lysine)-dye complexes in the presence of ascorbic acid. Dyes: (a) Mordant Violet 5 (CI 15670), ( b ) Mordant Black 15 (CI 15690) and (c) Mordant Black 17 (CI 15705).Analyst, April 199.5, Vol. 120 997 1600 1400 1200 1000 800 600 400 200 Wave nu m be r/cm-' Fig. 5 SERR spectra of poly(~-lysine)-dye complexes in the presence of ascorbic acid.Dyes: (a) Acid Orange 12 (CI 15970), (b) Food Orange 2 (CI 15980) and (c) Food Yellow 3 (CI 15985). I 1 I I I r J 1600 1400 1200 1000 800 600 400 200 WavenurnbeVcm-' Fig. 7 SERR spectra of poly(~-1ysine)-dye complexes in the presence of ascorbic acid. Dyes: (a) Acid Orange 14 (CI 16100), (b) Mordant Red 9 (CI 16105) and (c) Acid Red 26 (CI 16150). so; I I I I I I I I 1600 1400 1200 1000 800 600 400 200 Wavenumbe r/cm-' Fig. 6 SERR spectra of poly(L-lysine)-dye complexes in the presence of ascorbic acid. Dyes: (a) Acid Orange 16 (CI 16011), (6) Food Red 17 (CI 16035) and (c) Acid Red 13 (CI 16045). I I I I I I I 1 1600 1400 1200 1000 800 600 400 200 W aven u m be r/cm-' Fig. 8 SERR spectra of poly(~.-1ysine)-dye complexes in the presence of ascorbic acid.Dyes: (a) Food Red 6 (CI 16155), (b) Acid Red 27 (CI 16185) and (c) Acid Orange 10 (CI 16230).998 Analyst, April 1995, Vol. I20 The UV/VIS absorption spectra of the dyes in the test set (10-5 mol I - I ; 2 ml) were recorded after the addition of poly(I--lysine) solution (0.01%; 500 PI), and again after the addition of ascorbic acid (1 mol I--'; 150 pl) and compared with those obtained for the dye solutions prior to the addition of the poly(L-lysine) and the ascorbic acid. The addition of poly(I,-lysine) to the dye solutions at pH 6 resulted in changes in the absorption spectra. Hypsochromic shifts were observed for the o-hydroxyarylazo dyes and bathochromic shifts were 1600 1400 1200 1000 800 600 400 200 Wave nu m be r/cm-' Fig. 9 SERR spectra of poly(L-1ysine)-dye complexes in thc presence of ascorbic acid. Dyes: ( a ) Acid Red 44 (CI 16250) and (h) Acid Red 18 (CI 16255).Fig. 10 Proposed O H observed for the p-hydroxyaryl azo and the 0, o-dihydroxyary- lazo dyes. On the subsequent addition of ascorbic acid the hypsochromically shifted o-hydroxylarylazo dyes showed little change in the recorded spectra; a number showed a further slight hypsochromic shift. However, a hypsochromic shift was observed for the bathochromically shifted p-hydroxyarylazo dye and the o,o-dihydroxyarylazo dyes. The effects of poly(L-lysine) and the ascorbic acid on the o-hydroxyarylazo dyes indicate interaction between the dye molecules and poly(L-lysine) via the anionic sulfonic acid substituent.In each instance, the hypsochromic shift observed on the addition of poly(L-lysine) to the dye solutions at pH 6 was not as strong as that recorded when the pH was changed to 12, and clearly from the SERR data was not due to switching from the hydrazone to the azo tautomeric form. Instead, the hypsochromic shift may result from an increase in the electron-withdrawing nature of the sulfonic acid substituents as a result of their interaction with the protonated amino groups of the lysine residues. The further slight hypsochromic shift observed on the subsequent addition of ascorbic acid is also consistent with this model and is due to the promotion of protonation of the amino groups, enhancing the over-all process. The proposed model of interaction between poly(~- lysine) and the o-hydroxyarylazo dyes in the presence of ascorbic acid is illustrated in Fig.10. The observations for the p-hydroxyarylazo and the o,o- dihydroxyarylazo dyes cannot be explained by the same proposed model of interaction of poly(L-lysine) and ascorbic acid. The bathochromic shift observed for Acid Brown 102 (CI 14615) on addition of poly(L-lysine) is very similar to that observed at pH 12 and therefore is possibly due to the ionization of the molecule, followed by binding of the poly(L-lysine) at the new anionic site on the dye molecule in competition with binding at the sulfonic acid substituent. On the addition of ascorbic acid ionization would be hindered, favouring binding at the sulfonic acid group and resulting in a hypsochromic shift as observed.There is no obvious explana- O H HO % '1 O H It cY model of interaction of 7 H - - 0 O H poly(L-lysine) and ascorbic acid with an o-hydroxyarylazo dyc [Acid Orange 12 (CI 15970) 1.Table 1 SERRS frequencies (cm-l)* of poly(L-lysine)-dye complexes in the presence of ascorbic acid CI 14615 CI 15575 CI 15620 C115670 CI 15690 CI 15705 CI IS970 CI 15980 C115985 C116011 CI 16035 CI 16045 CI 16100 CI 16105 CI16150 CI 16155 CI 16185 CI 16230 CI 16250 CI 16255 1662 m 1603 vs (1) 1592 vs (2) 1577 m 1572 vs (4) 15.50 vs (2) 1552 vs (3) 1482 vs (3) 1510vs(l) 1451s(9) 1480 s (6) 1410 s (8) 1450 vs (5) 1376 s (7) 1400s(7) 1334vs(5) 1603 vs (5) 1599 vs (1) 1599 vs (2) 1575 vs (6) 1550 vs (5) 1550 s (8) lSSls(7) 1502vs(6) lSlOs(10) 1517s(9) 1480vs(3) 1480vs(3) 1480 vs (1) 1450 s (8) 1450 s (9) 1453 s (8) 1385 vs (4) 1385 vs (6) 1438 m 1337 vs (2) 1350 vs (4) 1402 m 1261 s (9) 1335 vs (1) 1372 s (1 1) 1329 s (8) 1274 m 1224 m 1195 m 1163 m 1137 m 1100 vw 1090 vw 1042 w 998 w 950 vw 925 vw 873 w 849 w 827 vw 780 vw 750 vw 725 vw 702 vw 624 vw 575 vw 520 w 475 m 426 vw 380 vw 350 vw 320 w 250 vw 1350s (9) 1302 s (10) - - I 1274 m 1363 vs (3) 1227 vs (7) 1260 s (1 1) 1257 m 1341 s (10) 11.58 m 1227 vs (4) 1288 m 1143 m 121 1 s (6) 1173m 1152 m 1140m 1098 m 1082 w 1040 w 989 w 914 w 869 w 806 w 722 m 689 w 652 w 610 w 570 w 550 w 518m 474 w 428 w 360 w 340 w 317 w 2x0 L w 223 w - - I - - __ 1260s(ll) ll00m 1231 vs (2) 1085 m 1213 vs (4) 1040 m 1161 m 1141 m ll00m 1026 w 988 w 945 vw 900 vw 872 w 819 w 786 w 740 w 711 w 688 vw 646 w 617 w 595 vw 532 w 500 w 480 w 428 w 347 w 300 w 275 vw - - - - - 990 m 940 w 880 w 828 w 770 w 730 m 695 w 665 w 610 w 540 w 525 w 473 w 430 w 335 vw 320 vw - - - - - - - - -.- - - - 1221 s (5) 1210 s (7) 1158m 1140 m 1098 m 1040 w 1015 w 995 w 955 vw 890 w 872 w 828 w 811 w 780 vw 767 vw 732 m 662 w 638 w 590 vw 562 vw 538 w 520 w 484 w 465 w 433 w 354 w 320 w 295 vw - - - __ - 1618s(4) 1594vs(3) 1598s(5) 1596vs(l) 1603m 1603m 1602m 1597vs(3) 1608s(5) 1623m 1607m 1600s(7) 1620w 1624w 1630m 1603s(5) 1548m 1551 m 1548s(8) 1582m 1582s(5) 1574s(5) 1550s(7) 1583m 1594s(4) 1587m 1573vs(5) 1590s(3) 1588m 1593m 1585s(6) 1492vs(2) 1482vs(2) 1499vs(6) 1548m 1550s(6) 1550m 1498vs(2) 1552s(4) 1533m 1547m 155Ovs(4) 1532m 1572s(2) 1576s(4) 1555 s (7) 1478 vs (4) 1433 m 1475 s (4) 1477 vs (2) 1501 vs (1) 1516 m 1480 s (6) 1490 vs (1) 1499 vs (3) 1488 vs (2) 1517 s (6) 1491 s (2) 1530 w 1538 rn ., ., 1518m ‘ 1433m 1388vs(4) 1417s(9) 1433m 1480s(3)’ 1479vs(2) 1507 m 1385 vs (5) 1337 vs (3) 1387 vs (3) 1383 s (4) 1437 w 1460 m 1480 m 1340 vs (6) 1290 m 1333 vs (5) 1340s (3) 1412 m 1438 m 1453m 1315m 1260m 1307m 1304m 1387s(7) 1403m 1357 vs (2) 1275 m 1230 vs (1) 1257 m 1262 m 1334 s (4) 1365 vs (1) 1228vs(2) 1232vs(l) 1270m 1328m 1334vs(l) 1258m 1178m 127Svs(3) 1231vs(l) 1131w 1215 m 1161 m 1148 m 1103 m 1049 w 1020 w 994 w 980 w 950 w 908 w 848 w 821 w 788 w 742 w 718 w 660 vw 647 w 559 w 547 w 484 vw 438 w 390 vw 354 vw 340 vw 318vw 292 vw __ - - 1176 m 1151 w 1131 w 1097 w 1078 w 1037 w 988 w 968 vw 928 vw 903 w 854 w 800 vw 739 m 688 vw 665 vw 619 vw 590 vw 545 vw 510 w 472 m 420 vw) 390 vw 360 vw 304 vw 225 w - - - - 1097 m 1040 w 992 w 904 w 822 vw 756 m 718 vw 687 vw 658 vw 617 vw 598 w 550 vw 513 w 474 m 450 vw 424 vw 385 vw 360 w 300 w 240 vw - - - - - - - - - 1180 s (7) 1157 m 1127 m 1093 m 1037 w 1006 w 985 w 920 vw 900 w 860 w 802 w 747 m 717 vw 673 w 638 w 600 vw 550 vw 533 vw 513 w 470 m 421 vw 357 vw 320 w 290 w - - - - - - 1160w 1130w 1092 w 1040 w 989 w 903 w 862 w 820 vw 783 w 731 m 683 vw 603 w 570 vw 550 w 530 w 520 w 469 m 426 vw 589 vw 358 vw 319 w 272 vw 227 w - - - - I I - 1262m 1290w 1224 vs (2) 1260 m 1 , 1191 m 1131 m 1096m 1073 vw 1038 w 994 w 904 w 856 w 834 vw 807 vw 756 s 729 w 698 vw 663 vw 641 w 597 w 537 w 494 m 440 vw 420 w 406 w 360 w 318 vw 298 w 278 vw 240 vw -- - - _- 1231 vs (4) 1218 vs (3) 1164 w 1133 m lloow 1040 w 1026 w 987 w 945 vw 904 w 843 w 796 vw 775 w 722 w 678 w 644 vw 618 w 597 vw 568 vw 536 w 507 w 491 w 437 vw 425 vw 405 w 357 vw 326 vw 293 vw 271 vw - ~, ., ., 1419m.’ 1453m 1463m 1480s(3)‘ 1482vs(2) 145.5~ 1513m 1518s(5) I384 s (5) 1417 m 1423 vs (2) 1416 m (I) 1462 m 1424 m 1484 m 1490 m 1347 vs (1) 1388 s (7) 1378 m 1378 m 1286 m 1261 m 1227 m 1188m 1172 s (4) 1141 m 1108 w 1080 vw 1056 w 1039 w 1003 w 939 m 900 w 842 vw 749 m 715 vw 678 vw 645 vw 619vw 586 vw 538 vw 480 m 422 vw 372 vw 355 vw 310 w 255 vw - - - - - - - - 1348 vs (2) 1330 m 1342 vs 1289 w 1299 s (5) 1299 m 1261 m 1277m 1273m 1222s(6) 1237vs(l) 1249m 1169vs(3) 1167m 1142m 1111 w 1086 w 1054 w 1040 w 1000 vw 940 m 904 w 858 vw 801 vw 750 m 686 vw 628 vw 587 vw 541 w 496 w 468 w 416 w 373 vw 358 vw 314 vw 279 vw 210 vw - - - - - - - 1141 m 1118w 1045 w 1007 vw 985 vw 941 w 921 vw 869 w 832 w 813 w 787 vw 713 w 652 w 624 vw 580 vw 556 vw 535 w 473 m 420 vw 394 w 368 vw 286 w 242 w - - - - I - - 1223 m 1180m 1168m 1138w 1102w 1052 w 1033 w 998 vw 939 m 896 w 819 vw 743 m 717vw 703 vw 630 vw 575 vw 559 w 492 w 472 w 435 vw 404 vw 376 vw 327 vw 278 vu’ 225 w I - - - - - 1437m 1376m 1450m 1460m 1401 s (10) 1328 m 1132 s (3) 1443 vs (3) 1363 vs (3) 1302 s (4) 1408 m 1403 m 1343 vs (1) 1280m 1372 m 1363 vs (2) ~, 1287 m 1252 1229 m s (9) 1207 m 1172s(8) 1138 m 1108 w 1054 w 1039 w 994 w 939 m 895 w 806 w 741 m 702 w 678 vw 637 w 618 vw 582 w 565 w 543 w 520 w 504 w 470 vw 433 vw 404 w 365 vw 350 vw 186 w 77s w - - 1234vs(l) 1351m 1318m 1178 m 1144w 1117w 1081 vw 1048 w 1002 vw 982 vw 943 w 867 vw 835 w 790 w 714 w 700 vw 620 vw 574 vw 550 w 517 vw 474 w 410 vw 392 vw 372 vw 325 vw 304 w 270 vw - __ - - - - - 1303 s (4) 1302 m 1252 m 1238 vs (1) 1238vs(l) 1219s(6) 1208 m 1178 w 1146 w 1122 w 1090 vw 1048 w 982 vw 945 w 884 vw 824 w 794 vw 758 vw 745 vw 696 m 636 vw 620 vw 580 vw 567 w 532 w 517 w 481 vw 427 \#w 390 vw 372 vw 347 vw 317 vw 271 w 222 VH 1167 w’ I150 w 1126 w 1051 w 1030 vw 987 vw 946 w 860 vw 829 w 795 vw 767 vw 697 m 648 vw 620 w 585 w 542 w 502 w 475 vw 429 w 393 vw 367 vw 338 vw 293 w 268 vw - - - - * vs = Vcry strong; s = strong; rn = medium; w = weak; vw = very weak; - = no band.1000 Analyst, April 1995, Vol.120 tion for the effect of poly(L-lysine) and ascorbic acid on the o.o-dihydroxyarylazo dyes from these observations alone. The effect on the 0, o-dihydroxyarylazo dye Mordant Violet 5 (CI 1.5670) was examined at a series of concentrations (1 x 10-5-2 x 10-4 mol 1-1). To reproduce better the effect of poly(L-lysine) at various dye concentrations, the concentra- tion of the poly(L-lysine) was increased accordingly (0.01% to 0.2% m/v) to maintain the ratio of lysine residues to dye molecules. On the addition of poly(L-lysine) to the highest concentration Mordant Violet .5 solution (2 x 10-4 rnol 1-1) no bathochromic shift was observed in the UV/VIS spectrum. However, on dilution of the mixture with distilled water a bathochromic shift was observed. Further investigations confirmed that at a fixed ratio of lysine residues to dye molecules the effect of the poly(L-lysine) is dependent on the concentration of the dye and also on time.At concentrations below .5 X 10-5 rnol 1-1 strong bathochromic shifts are observed. At higher concentrations the initial shifts observed were considerably smaller, but increase when the poly(L- 1ysine)-dye mixtures were left for several days. A plot of absorption (SO0 nm) versus the concentration of aqueous solutions of Mordant Violet 5 (Fig. 11) indicates a deviation from Beer's law above 5 x 10-5 mol 1-1, consistent with the aggregation of dye molecules and the formation of dimers that is typically observed in the concentration range 10-4-10-6 It has been reported that an equilibrium exists between the dye monomer and dimer species in solution.17-*9 From the results of this study it has been observed that the number of mol 1- 1.17-19 O.;: 12 16 20 Concentrationll w5 mol I-' Fig.11 Graph of absorbance (500 nm) versus concentration of Mordant Violet 5 (CI 1.5670). A, absorbance measured and B, absorbance calculated. O H free monomer units is decreased on the formation of poly(i_-1ysine)-dye complexes, and therefore, in order to maintain equilibrium, a number of the dimer species will split to form dye monomers. The interaction of the poly(r.-lysine) with the released monomers will continue to upset the equilibrium, repeating the process and resulting in the increase in bathochromic shift with time observed at concen- trations above 5 x 10-5 rnol 1 - 1 .These observations indicate that the effect of poly( 1.-lysine) is greatly hindered by the formation of dimers at high concentrations in aqueous solution, suggesting that the sites of poly(L-lysine) interaction on the dye molecules are involved in dimerization. The literature suggests that parallel plane dimers are formed, with interaction of the resonance circuits of aliphatic or cyclic systems of double bonds, i.e., the two-ring systems and the azo group.18-20 Aggregation does not involve the sulfonic acid groups, which would in fact promote solvation of the molecule, thus hindering dimerization. This would suggest that the site of poly(L-lysine) interaction that induces the bathochromic shift is not the anionic sulfonic acid substituent of the dye molecule.In the presence of chromium(iir), cobalt(Ii1) and copper(i1) ions, the mordant dyes act as tridentate ligands, forming complexes with the metals via the two o-hydroxy groups and the azo group.13 Correct conformation of the dyes in the azo tautomer is essential for complex formation of this type and both o-hydroxy groups are required to be on one side of the plane of the azo group before bonding with the metal centre can occur. On the formation of parallel plane dimers, the monomer dye units will be held in a fixed confirmation with the two o-hydroxy groups oriented on opposite sides of the plane of the azo group. Thus, the formation of dye-metal complexes is largely prevented by dimerization and high dye concentrations. It is proposed that the protonated amino groups of the lysine residues are complexed with the dye in a similar fashion.At low concentrations (<5 x 10-5 mol I-]), this interaction will affect the azo-hydrazone tautomeric equilibrium in favour of the azo form. This is consistent with the bathochromic shift observed in the visible absorption spectra and the observation that the SERR spectra are in the azo tautomeric form. On addition of ascorbic acid, the hydrazone form would be stabilized, preventing complex formation of this type. In this case the poly(L-1ysine)-dye interaction would occur via the sulfonic acid group. This is consistent with the hypsochromic shift observed in the visible O H . 1 1 H I . HO %c N' Ascorbic acid - w 0 -0,s N T +N I o~ 1 2 Fig. 12 ascorbic acid being prescnt. Proposed modcl of interaction of poly(L4ysine) with 1, an o,o-dihydroxyarylazo dye (Mordant Violet 5 ) and 2, the result ofAnalyst, April 1995, Vol.120 1001 absorption spectra and the SERRS of the hydrazone tau- tomeric forms on the addition of ascorbic acid. The proposed model of interaction between the poly(L-lysine) and the o, o-dihydroxyarylazo dyes with and without the presence of ascorbic acid is illustrated in Fig. 12. Mordant Red 9 (CI 16105) also acts as a tridentate ligand, but chelation is notably weaker via the carboxylate group of this dye type than via a hydroxy group and hence it acts in a similar fashion to the other o-hydroxyarylazo dyes. In the presence of ascorbic acid, the bonding of all the acidic monoazo dyes to the poly(L-lysine) is proposed to be analogous to the action of these dyes in the colouring of wool fibres.The lysine residues of the wool a-keratin are the primary sites of attachment of the anionic dye molecules. Under the correct conditions for dyeing, the amino groups of the residues will become protonated, attracting the negatively charged dye molecules. In a similar fashion, the ionic interactions between the poly(L-lysine) and the sulfonic acid groups of the dye molecules lead to the formation of poly( L-1ysine)-dye complexes. The proposed model of inte- raction between poly(L-lysine) and the full set of acidic monoazo dyes individually in the presence of ascorbic acid is the same as that for o-hydroxyarylazo dyes (Fig. 10). Role of poly(L-lysine) andAscorbic Acid in the SERRS Procedure The protonated amino groups of the unbound lysine residues of the poly(L-1ysine)-dye complexes are attracted to and readily adsorbed onto the negatively charged organic layer at the surface of the sol particles, leading to controlled aggrega- tion of the particles and an intense SERRS effect.The amount of ascorbic acid used will promote the protonation of the lysine residues and will also hinder the ionization of the p-hydroxylated and the 0, o-dihydroxylated dyes. It does not directly promote aggregation and thus provides a more stable aggregate than that obtained on the addition of a mineral acid, e.g., nitric acid or hydrochloric acid. Ascorbic acid is a mild reducing agent capable of cleaving monoazo species at the N=N bond to form two colourless primary amines.However, reduction of these dyes was found to be negligible under the present conditions. From the absorbance spectra recorded at a concentration where linearity is observed for Beer’s law, a maximum of 7.5% of azo dye was found to be reduced over 100 h. Poly(L-lysine) is commonly used for the determination of the secondary structure content of proteins by Raman I spectrometry.21.22 As such, the Raman spectra of the a-hel- ical, (J-sheet and random coil conformations are well charac- terized. Under the conditions used in this study, the literature would support a preference for the random coil conforma- tion.23 For random coiled poly(L-lysine) in solution, the amide I and 111 frequencies are reported to be at 1665 and 1243-1248 cm-1, respectively. However, these bands are absent in the SERR spectra of the poly(L-lysine)-dye com- plexes indicating that poly(L-lysine) makes no observable contribution to the spectra.Comparison of the SERRS spectra with the RR spectra of the individual dyes confirmed that the Raman bands observed can be attributed in full to the dye molecule. This observation is attributed to the magnitude and selectivity of SERRS enhancement. The excitation wavelength (457.9 nm (lies directly under the principle absorbance bands of the dyes examined. However, poly(~- lysine) does not absorb in the visible region. The principle absorption band is in the vacuum ultraviolet region (approxi- mately 218 nm). Although the poly(L-lysine)-dye complex may form an extended chromogen, only the bands corre- sponding to certain vibrations with atomic displacements within the resonant chromophore, i.e., the parent dye structure, will be enhanced.Therefore, Raman scattering due to the vibrations of the poly(L-lysine) are not observed in the SER spectra as the intensity of these bands is very small relative to the SERR bands of the parent dye structure. Reproducibility of the SERRS Procedure Surface enhancement is greatest when aggregation is induced in the silver colloids as the electromagnetic field is strongest in the interstices of the aggregates. Therefore, the stability and reproducibility of the aggregation procedure are vital to ensure a consistent surface enhancement of the Raman-active species. This is of particular importance when scanning instrumentation is employed to ensure that the degree of surface enhancement is maintained throughout the duration of a single scan.Otherwise the relative intensities of bands will be falsely represented. Precise sample alignment is also very important for all Raman spectrometry and small variations can greatly affect the scattering intensity observed, thereby increasing the between-run error. The SERR spectrum (1000-1700 cm-1) for a single colloidal mixture aggregated by the above procedure was recorded six times at 20 min intervals with the sample cell being removed and replaced between each scan. The relative standard deviations (s,) in scattering intensity (counts s-1) for four individual Raman bands were all found to be approximately 4.8%. This was found to be consistent across the set of dyes.This was repeated for a sample of pure ethanol. The s, in scattering intensity fos the principle Raman band of ethanol (885 cm-1) was found to be 1.9%. This corresponds to the random error associated with minor fluctuations in excitation intensity, the precision of photon counting and the precision of sample alignment. Therefore, the within-run error resulting from instability of the aggregates with time should be no greater than 3%. The SERR spectra of the 20 dyes were recorded at various undetermined intervals over an 8-week period. The same instrumentation was used for all analyses but three separately prepared silver colloids and six separate poly( L-lysine) solu- tions (three each from two batches) were used. In addition, ascorbic acid solutions were freshly prepared before each analysis.The between-run error varied between individual dyes. The s, for the principle band of each ranged between 5.7% for CI 15690 and 25.0% for CI 16035 (means, = 13.0%). A notable feature was that low between-run errors were observed for the p-hydroxy- and 0, o-dihydroxyarylazo dyes. However, no other relationship between dye structure and between-run error provided an explanation for the large variation observed. The deviation observed in vibrational frequency was negligible (<3 cm-1) and could be attributed to operator error. Concentration Dependence and Detection Limits The SERRS for Acid Orange 10 (CI 16230) was recorded at a number of initial dye concentrations <lO-5 rnol 1-1. Plots of initial dye concentrations of 0-3 x 10-6 rnol 1-1 and 0-10-5 rnol 1-1 versus scattering intensity (1234 cm-1) are illustrated in Fig.13. Over the concentration range 0-3 x 10-6 mol 1-1, the plot is linear, but the deviation from linearity is outwith the expected within-run error at concentrations above 3 x 10-6 rnol 1-1. At higher concentrations (3 x 10-6-1 x 10-5 mol l-l), increased absorption of the radiation by the dye results in a reduction in scattering intensity from that expected. The linearity at concentrations <3 x 10-6 mol 1-1 supports the application of this SERRS procedure for both qualitative and semi-quantitative analyses of trace amounts of dyes.1002 Analyst, April 1995, Vol. 120 The final concentration examined corresponded to a total amount of dye of approximately 300-500 pg.However, this is not the true detection level as only a small portion of the 2.5 ml of colloidal suspension is irradiated. A fraction of the bulk sample size may be examined easily by Raman micro- scopy, improving sensitivity, and charge-coupled device (CCD) detection is expected to further this improvement. Fingerprint Analysis Resonance enhancement plays a major role in the SERRS of the acidic monoazo dyes and, as with the resonance Raman spectra, strong similarities in the vibrational frequencies were expected for dyes that share the same chromophore. The differences observed in the SERR spectra are due to the effect of the auxochromes on specific normal vibrational modes of the chromophore, resulting in shifts in the vibrational frequen- cies, and are also due to the influence of the auxochromes on the electronic structure and therefore the relative intensities of each band.The differences in relative intensity are more significant than the shifts in vibrational frequency and greatly aid discrimination between the dyes. Discrimination between all the dyes was possible on the basis of their five principal bands compared in order of relative 80 I B 3 60 Y > 2 40 \ c .- a 0 - .- f 20 t: 0 8 0 10 20 30 0 40 80 Concentration/lo-’ mol I-’ Fig. 13 Graph of SERRS intensity (1234 cm-1) versus initial dye concentration (Acid Orange 10 (CI 16230). Initial dye concentration ranges: (a) 0-3 x mol I-1 and (b) 0-10-5 mol 1-1. Table 2 Five principal bands in order of relative intensity of the test set of 20 acidic monoazo dyes.Principal bands required for discrimination of individual bands are in bold type Dye Principal SERRS bandkm-1 Colour Generic name Index No. 1 2 3 4 5 Acid Orange 12 CI 15970 Acid Orange 10 CI 16230 Food Orange 2 CI 15980 Acid Orange 16 CI 16011 Acid Red 26 CI 16150 Acid Red 44 CI 16250 Acid Red 18 CI 16255 Mordant Black 15 CI 15690 Mordant Black 17 CI 15705 Acid Orange 14 CI 16100 Food Red 6 CI 16155 Acid Red 27 CI 16185 Acid Red 13 C116045 Acid Red 88 CI 15620 Mordant Red 9 CI 16105 Acid Brown 102 CI 14615 Food Red 17 CI 16035 Acid Orange 8 CI 15575 Mordant Violet 5 CI 15670 Food Yellow 3 CI 15985 123 1 1234 1230 1232 1237 1238 1238 1335 1334 1347 1342 1343 1365 1480 1490 1510 1501 1603 1599 1596 1492 1491 1482 1477 1423 1572 1363 1599 1357 1498 1488 1488 1479 1231 1348 1592 1224 1550 1337 1228 1594 1590 1337 1340 1499 1432 1443 1480 1275 1597 1480 1363 1218 1363 1169 1552 1480 1482 1480 1387 1478 1385 1302 1424 1388 1598 1383 1548 1594 1299 1303 1484 1576 1518 1350 1221 1618 1603 1172 1384 1378 1223 1550 1573 1231 1574 1213 1603 1552 1608 1572 1450 1334 1582 1227 1334 1385 1550 1475 1333 intensity.The five principal bands of the acidic monoazo dyes are reported in Table 2. The identification of one of the 20 dyes is possible on the basis of the first principal band, 13 dyes require two bands, two dyes require three bands, two require four bands and the final two dyes require all five principal bands to ensure complete discrimination. Blind Triuls Six unknown samples (A-F) were examined as a blind trial to assess the above SERRS procedure.Initial SERRS examina- tions were carried out for each sample without purification of the dye mixture. The vibrational frequencies and the relative intensities of the five principle bands for each sample were compared with those recorded for the 20 dyes in the test set. The vibrational frequencies of the principle bands in order of intensity for each sample are listed in Table 3. From the initial examination, samples C, D and F were correctly identified as each containing single dye components, Food Red 17 (CI 16035), Acid Red 27 (CI 16185) and Food Orange 2 (CI 15980), respectively. Sample B was correctly identified as containing two dye components, Acid Red 44 (CI 16250) and Acid Red 18 (CI 16255). The recorded spectrum for this mixture was dominated by Acid Red 44, although the actual mixture was 1 + 1.TLC indicated more clearly that the sample mixture was approximately 1 + 1 and enabled the SERR spectra to be recorded for the individual components of sample B [Acid Red 44 (CI 16250) and Acid Red 18 (CI 16255)l extracted from the TLC plate. Samples A and E were identified as both being phenylazo- naphthol dyes, but were not believed to correspond to any of the dyes in the test set. This was confirmed for sample E, which was revealed to be the acidic bis-azo dye Biebrich Scarlet (CI 26905). However, the initial examination had failed to identify sample A from the dye test set. TLC of sample A indicated the presence of a second minor dye component (RF = 0.39) in the sample mixture in addition to the principle dye component (RF = 0.57).From the subse- quent SERRS examination of the predominant component extracted from the TLC plate, sample A was found to have new principle bands at 1237, 1425, 1501,1595 and 1300 cm-1, and was correctly identified as containing Acid Red 26 (CI 16150). Although Acid Red 26 was the predominant com- ponent of sample A, the absorbance maximum of the unknown minor dye component was approximately 480 nm compared with approximately 505 nm for Acid Red 26. Therefore, with excitation at 457.9 nm the resonance enhan- cement will be greater for the minor component. Conclusions The initial resonance Raman studies indicate that Raman scattering can be applied to the characterization of acidic monoazo dyes. By the comparison of the RR spectra discrimination between the 20 dyes examined, including Table 3 Five principal bands in order of relative intensity of the unknown dye samples Principal bandkm- Blind trial sample 1 2 3 4 5 A 1419 1235 1593 1497 1381 B 1237 1431 1572 1298 1358 C 1498 1222 1478 1332 1580 D 1345 1480 1365 1550 1573 E 1480 1392 1602 1450 1332 F 1228 1480 1335 1388 1598Analyst, April 1995, Vol.120 1003 ~~ ~~ structural isomers, was achieved. However, some difficulties were still experienced owing to the underlying fluorescence background, the narrow concentration range over which scattering is observed (10-4-10-3 mol 1-1) and the relatively high detection limit. Therefore, although highly selective, RR spectrometry does not provide the sensitivity required.Addition of an aqueous solution of each dye to the silver sol produces no aggregation or SERRS. This is attributed to poor adsorption of the anionic dye molecules to the sol particles due to the negatively charged citrate layer on the surface of the silver. However, the addition of the poly(L-lysine) solution, prior to that of the dye solution, produces aggregation and intense SERRS of the poly( L-1ysine)-dye complexes. In addition to an enhancement of approximately 105-106-fold in scattering intensity compared with solution resonance, the fluorescence background that partially obscures the RR spectra for many of the dyes is quenched by radiationless energy transfer to the metal surface. The bonding of the poly(L-lysine) with the acidic monoazo dyes is dependent on the subset to which the individual dye belongs. For the o-hydroxyarylazo dyes the effect of poly(L- lysine) of the UV/VIS spectra suggests the interaction of the protonated amino group of the lysine residues with the sulfonic acid sites on these dyes.The presence of ascorbic acid promotes the protonation of the amino groups and increases the efficiency of the process. On the addition of poly(L-lysine) to the p-hydroxyarylazo dyes ionization occurs and subse- quent binding at the new anionic sites is in competition with binding at the sulfonic acid substituent. The addition of ascorbic acid hinders ionization and favours binding at the sulfonic acid group. For the 0, o-dihydroxyarylazo dyes the addition of poly(L-lysine) results in the ionization of the two hydroxy groups.The ionized dyes act as tridentate ligands, forming complexes with the protonated amino groups of the poly(~4ysine) via the two o-hydroxy groups and the x-elec- trons of the azo group. The addition of ascorbic acid prevents ionization and favours binding at the sulfonic acid groups of the dyes. For the last two subsets of dyes the interaction of poly(L-lysine), in the presence of ascorbic acid, appears to revert to that observed for the former. This is reflected in the observed SERR spectra. Therefore, a single model can be used to describe the action of poly(L-lysine) with the set of acidic monoazo dyes collectively. The between-run error varied greatly between individual dyes. However, the within-run error was both consistent and low across the set (s, d 5 % ) , indicating the possibility of quantitative dye analysis. Linearity of concentration versus scattering intensity was observed at low concentrations (<3 x 10-6 mol 1-1). This supports the application of this SERRS procedure for both qualitative and semi-quantitative analysis of trace amounts of acidic monoazo dyes. The findings of the blind trials confirm the usefulness of SERRS for qualitative analysis. Howcver, the importance of sample purity is also demonstrated, indicating that the technique may be of greatest use in forensic science following an initial TLC examination of unknown dye samples. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 References White, P. C., and Harbin, A.-M., Analyst, 1989, 114, 877. Lee, P. C., and Mcisel, D., J . fhys. Chern., 1982, 86, 3391. Hildebrandt. P., and Stockburgcr, M., J. Phys. Chem., 1984, 88, 5935. Xu, Y., and Zheng, Y . , Anal. Chim. Actu. 1989, 225, 227. Sheng, R.-S., Zhu, L., and Morris. M. D., Anal. Chem.,. 1986, 58, 1116. Xi, K., Sharma, S . K., and Mucnow, D. W., 1. Ramuii Spectrosc. , 1992, 23, 62 1. Xi, K., Sharma, S. K., Taylor, G. T., and Mucnow, D. W., Appl. Spectrosc.. 1992, 46, 819. Tran, C. D., Anal. Chem., 1984, 56, 824. Kncipp, K., Hinzmann, G., and Fassler, D., Chern. fhys. Lett., 1983, 99, 503. Ohshima, S . , Kajiwara, T., Hiramoto, K.. and Sakata, T., J. Phys. Chem., 1986, 90, 4474. Pincda, A. C., and Ronis, D. J., J . Chem. Phys., 198.5,83,.5330. Munro, C . H., Smith, W. E., and White, P. C., Analyst, 1993, 118, 731. Gordon, P. F., and Gregory, P., Organic Chernistrly in Colour, Springer, Berlin, 1983. Sagaster, H.-R., Schadlich. H., and Robisch, G., Z. Chern., 1987,27, 298. Munro, C. H . , Smith, W. E.. Armstrong, D. R., and White. P. C., J. Phys. Chem., 1995. 99, 879. Jolivet, J. P., Gzara, M., Marieres, J., and Lefebvre, J., J. Colloid Interfuce Sci., 1985, 107, 429. Jacobson, B. S., and Branton, D . , Science, 1977, 195, 302. Monahan, A. R., and Blosscy, D. F., J . fhys. Chem., 1970,74, 4014. Monahan, A. R., Germano, N. J . , and Blossey, D . F., J . Phys. Chem.. 1971, 75, 1227. Sheppard, S. E., and Geddcs, A. I., J . Am. Chem. Soc., 1944, 66, 1995. Chen, M. C., and Lord, R . C., J . Am. Chem. SOC., 1974, 96, 4750. Lippert, J. L., Tyminski, D., and Desmeules, P. J . , J. Am. Chem. SOC., 1976, 98, 707.5. Yu, T.-J.. Lippert, J . L., and Peticolis, W. L., Biopolymers, 1973, 12, 2161. Puper 4106415A Received October 19, 1994 Accepted November I , 1994

ISSN:0003-2654    

DOI:10.1039/AN9952000993

出版商:RSC    

年代:1995

数据来源: RSC