ISSN:0144-557X    

DOI:10.1039/AP98926FX025

出版商:RSC    

年代:1989

数据来源: RSC

摘要:

ANPRDI 26(7) 249-280 (1 989) Proceedings of the Analytical Division of The Royal Society of Chemistry 249 Reports of Meetings: Joint Pharmaceutical Analysis Group; Training of Analytical Chemists for Developing Countries 250 Royal Society of Chemistry Awards 1988 250 Analytical Division Honours 250 Royal Society Fellowship 25 1 Analytical Viewpoint ‘Modern Analytical Chemistry’ by Julian F. Tyson 255 SUMMARIES OF PAPERS 255 Fourth Biennial National Atomic Spectroscopy Symposium 255 258 260 ‘Use of the Hydride Generation Technique in the Determination of Bismuth with a d.c. Plasma Atomic Emission Spectrometer’ by Paavo Peramaki, Veli Matti Korvala and Lauri H. J. Lajunen ’Improvement in the Determination of Bismuth by Flame Atomic Absorption Spectro- metry Using a New Design of Slotted Tube Atom Trap’ by Narong Chimpalee, Michael Harriott and D. Thorburn Burns ‘Use of Surface Coatings in the Determination of Bis(tributy1tin) Oxide in Freshwater by Using Graphite Furnace Atomic Absorption Spectrometry’ by C. Donaghy, M. Harriott and D. Thorburn Burns 263 Industrial Applications of IR and Raman Spectroscopy 263 264 ’Applications and Limitations of Fourier Transform Raman Spectroscopy‘ by F. J. Bergin and H. F. Shurvell ‘Fermentation of Cheese Whey-Monitoring by FT - IR‘ by P. Fairbrother, W. 0. George and J. M. Williams 268 Equipment News 275 Ronald Belcher Memorial Lectureship 276 RSC Interdisciplinary Awards 1989 276 Conferences and Meetings 278 Courses Typeset and printed by Black Bear Press Limited, Cambridge, England Analytical Proceedings CONTENTS July 1989

ISSN:0144-557X    

DOI:10.1039/AP98926BX027

出版商:RSC    

年代:1989

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS, JULY 1989. VOL 26 249 Reports of Meetings Joint Pharmaceutical Analysis Group The nineteenth Annual General Meeting of the Group was held at 2.15 p.m. on Thursday, March 16th, 1989, at the Royal Pharmaceutical Society of Great Britain, 1 Lambeth High Street, London SE17JN. The Honorary Secretary presented the Annual Report for 1988. The three nomi- nations for committee members matched the number of vacancies on the commit- tee, hence no election had been held and the three nominated people were declared elected unopposed. The Com- mittee of Management for 1989 will be: Chairman-Mr. D. W. Houghton. Honorary Secretary-Miss M. L. Rabou- hans. Immediate Past Chairman-Dr. P. R. Wood. Ordinary Members-Dr. A. H. Andrews, Dr. G . P. R. Carr, Dr. B. V. Fisher, Mr.P. Graham, Dr. R. C. Hutton and Dr. B . R. Matthews. Members nomi- nated by the sponsoring bodies-Dr. W. G . Thomas (Royal Pharmaceutical Society of Great Britain), Dr. A. Mathias (Royal Society of Chemistry, Analytical Division) and Professor W. B. Whalley (Royal Society of Chemistry, Professional Affairs Board). Training of Analytical Chemists for Developing Countries The following is a report of a meeting of the North West Region of the Analytical Division of the Royal Society of Chem- istry held in the University of Salford on Wednesday, February 8th, 1989, entitled “Some Problems Associated With the Training of Analytical Chemists for De- veloping Countries.” The meeting was Chaired by Dr. C. Peacock, Vice-Chair- man of the Region. The topic was introduced by Professor L.S. Bark, who discussed examples of the effects of a shortage or non-availability of services which are normally provided in the developed countries in laboratories where analytical chemistry is carried out. These include a constant and plentiful supply of water, capable of being used for cooling purposes, for use in stills, etc., to provide water of acceptable analytical purity, an uninterrupted and constant voltage supply, a reasonable access to spares for equipment, to laboratory chemicals, to libraries and other sources of reference materials and to the services of the support staff normally associated with analytical laboratories. The need to ensure that all postgradu- ate workers from developing countries who were trained in this country had some basic training in recognising and remedy- ing simple faults in basic equipment was emphasised, with examples from first- hand experience of problems that were readily solved by the application of lateral thinking.He noted the fact that many training establishments in the less deve- loped countries did not face the trainee with some of the problems encountered in ensuring that laboratories run smoothly, and emphasised that equipment servicing, adequate stocktaking and basic labora- tory management were essential parts of all analytical chemists’ laboratory training and should be included in postgraduate courses in analytical chemistry. He quoted examples of equipment being left to decay because of simple faults being unremedied as a result of the attitude of analytical chemists who had never been exposed to the need to ensure that they made their equipment work, that they standardised it whenever nec- essary and that, as skilled professional analytical chemists, it was part of their responsibilities to ensure that their lab- oratory functioned efficiently, taking into account the provision of basic services as well as those more particular to analytical chemistry.The various methods of train- ing graduate workers were discussed. Professor Bark indicated that for PhD training he favoured the “integrated” or “split” method, whereby a graduate spent part of his time at a UK University and part at his own University, being super- vised and directed in a piece of research work of immediate application to the economy of his home country. First-hand experience of this in several instances revealed that the graduate gained the confidence needed to continue to carry out research after finishing the PhD pro- gramme and was able to start research on viable topics immediately after gradua- tion.The method also has the great advantage that the worker generally has not lost contact with his employers during the training period and has also becove aware of the actual problems involved in carrying out research in a developing country whilst still having the advantage of immediate advice from a research supervisor. The rest of the meeting took the form of a forum. Dr. C. A. Taylor (Liverpool Polytechnic) discussed the training of analytical chemists in Thailand and gave examples of the types of syllabus used in the undergraduate courses of the Univer- sity of Chiengmai; his discussion was illustrated by slides showing the types of laboratories, the major pieces of equip- ment available and the results of some of the applied analytical chemistry projects that had been undertaken by various groups of students.Dr. T. Wallace (Uni- versity of Salford) gave an illustrated discussion of training undergraduates in Papua New Guinea and in Dar-es-Salaam in Tanzania. He mentioned unusual prob- lems that had been encountered, includ- ing that of ensuring that students realised the necessity of wearing adequate foot protection, viz., shoes, in laboratories and the problems associated with low atmospheric pressures in university lab- oratories at high elevations.He gave examples of the lengths of time required for the delivery of chemicals aCter they had been ordered, indicating that not only did the usual problem of having sufficient departmental funds available raise its head, as in all departments whether in developing countries or otherwise, but that the lack of up to date prices for deliveries from the chemical distributors to the university and then the additional problems associated with quotas of foreign exchange created problems not normally encountered in the UK. Dr. A. 0. Fitton (The Overseas Students Advisor for the University of Salford), discussed some of the adminis- trational problems associated with the application and ultimate acceptance of overseas students for work in universities. The roles of the various aid agencies in providing funds for postgraduate workers and for the training of support staff, both in the UK and in the developing coun- tries, were briefly reviewed.Examples of academic links funded by the British Council and the EEC were quoted as illustrations of the types of co-operation that exist for the training of both pro- fessional chemists and support staff. Professor D. Mosha (University of Dar-es-Salaam) gave examples of the effects of academic links on the wellbeing of a Department of Chemistry in a devel- oping country and cited situations where more help should be targetted. He emphasised the need for continued train- ing of technical support staff and the need for help from the developed countries in providing spares, etc., for equipment.He emphasised that there was a need to have the active co-operation of fellow pro- fessional chemists when such items were being ordered and purchased through any of the aid schemes. The need to have integrated training using part of the train- ing time in the UK and the remainder in the graduate’s own university he con- sidered to be an essential part of the modern system of training graduate work- ers. The advantages of such schemes far outweighed the administrational prob- lems that are encountered. Mr. J . D. Openshaw (University of Salford) contributed from his wide experiences of setting up training schools in electrical and electronic engineering for technicians in several developing coun- tries and in establishing intensive short courses in instrumental maintenance in250 the UK for the training of technicians from overseas educational institutions.He amplified several of the problems mentioned by other speakers with examples from his experience of instances where even a small amount of training in basic instrumental maintenance had saved, or could have saved, relatively large amounts of lost time and money. When the discussion was thrown open there were contributions from speakers from several different countries, includ- ing The People’s Republic of China, Egypt, Indonesia, Iran, Mexico, Nigeria, Saudi Arabia, Tanzania, USA, as well as from the UK. One theme that caused lively discussion was the apparently perceived attitude of the RSC towards research workers who graduated with UK qualifications and applied for election to ANALYTICAL PROCEEDINGS, JULY 1989, VOL 26 professional status.The general feeling of most of the chemists present seemed to be that they needed to be recognised as professional chemists. The status of the RSC qualifications was of importance for all those who were intending to become professional analytical chemists on returning to their native land. The prob- lems associated with the payment of subscriptions were also raised and it felt that there should be some attempt made to alleviate these. Several of the speakers from the floor enquired about the situation regarding the possible supply of text-books, jour- nals, etc., to developing countries and the possible provision of a pool of equipment, surplus to UK institution’s requirements, that could be used by institutions in developing countries. Professor Bark summarised the actions of the Interna- tional Committee of the Council of the RSC with regard to several of these points. Although the meeting commenced at 4.30 p.m. and officially closed at 6.45 p.m., when the Section provided light refreshments for the (at least) SO people who attended the meeting, in fact the meeting adjourned to the Junior Com- mon Room and continued for at least 20 of the participants until well past 8.00 p.m. (Comments made to the reporter subsequent to the meeting indicated that several of the people who attended had not previously been aware of the role of the RSC in the training of professional chemists o r in furthering progress in chemistry outside the UK.) L. S. BARK

ISSN:0144-557X    

DOI:10.1039/AP9892600249

出版商:RSC    

年代:1989

数据来源: RSC

摘要:

250 ANALYTICAL PROCEEDINGS. JULY 1989, VOL 26 Analytical Division Honours At its meeting on May loth, the Ana- I. D. Wilson (ICI Pharmaceuticals) and lytical Division Council approved the Dr. P. J. Worsfold (University of Hull). following recommendations from its Nineteenth and twentieth Analytical Honours Committee. Division Distinguished Service Awards: Seventeenth and eighteenth Society for Dr. A. M. G. Macdonald (University of Analytical Chemistry Silver Medals: Dr. Birmingham) and Dr. A. M. Ure (Strathclyde University, formerly of the Macaulay Land Use Research Institute). Schools Lecturer for 1990/1: Professor D. Betteridge (BP Research, Sunbury on Thames). L. S. Theobald Lecturer: Dr. J. A. W. Dalziel (Birkbeck College, Lon- don). Royal Society Fellowship At its meeting on March 16th, 1989, the Royal Society elected Professor T. S. West, CBE, Emeritus Professor of Chemistry in the University of Aberdeen and formerly the Director of the Macaulay Land Use Research Institute, a Fellow.

ISSN:0144-557X    

DOI:10.1039/AP989260250b

出版商:RSC    

年代:1989

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS, JULY 1989, VOL 26 25 1 Analytical Viewpoint The following is a member of a continuing series of articles providing either a personal view of part of one discipline in analytical chemistry (its present state, where it may be leading, etc.), or a philosophical look at a topic of relevance t o chemists in general or analytical chemists in particular. These contributions need not have been the subject of papers at Analytical Division Meetings. Persons wishing t o provide an article for publication in this series are invited t o contact the editor of Analytical Proceedings, who will be pleased t o receive manuscripts or t o discuss outline ideas with prospective authors. Modern Analytical Chemistry Julian F. Tyson Department of Chemistry, University of Technology, Loughborough, Leicestershire LE I I 3TU The supply of analytical chemists has been of concern to the Royal Society of Chemistry (RSC) for some years now.In 1980, the RSC published a report1 of a working party which, amongst other courses of action, recommended that: “(a), improvements are made in the education of analytical chem- ists; and (b), educational establishments should be encouraged to pay more attention to the coherent teaching of analytical chemistry (both theoretical and practical) within the over-all chemistry course.” More recently the RSC’s activities in the production of indicative registers of chemists with particular types of exper- tise has been discussed in the Society’s Professional Bulletin.2.3 The most recent of these stated “The work of professional chemists extends over a broad and diverse range of activities, fields and specialisms, many of which involve responsibilities to maintain standards of quality and safety in the public interest- sometimes (and increasingly) under legislative requirements” and went on to announce that “The Society has already identified several specific groupings of chemists where there is both a need and a demand for a register-a need by the public for a means of identifying competent practitioners in a given field, and a demand for the services that members can provide.We have already reached an advanced stage in developing proposals for indicative registers in two areas-analytical chemistry and health and safety.” The introduction of such a register of analytical chemists has implications for the provision of analytical chemistry teaching in the UK.Almost certainly, following a transition period in which existing practitioners are registered, entry to the register will be open only to those professional members of the Society who have satisfied the requirements of an appropriate study guide. As the register will only be open to Members and Fellows, it seems likely that the contents of the study guide will resemble more closely the contents of an MSc course rather than the recently introduced ACOL programme,4 a distance learning scheme at the senior technician level. It is difficult to assess accurately the current provision of analytical chemistry teaching in British universities and poly- technics, as no detailed survey has been made since 1979.1 A superficial surveys of the present-day level of activity in universities compared with that of the early 1970s suggests that there has been a considerable decline.That the UK is considerably out of step with the rest of Europe is shown in the results of a survey6 conducted by the Working Party on Analytical Chemistry (WPAC) of the Federation of European Chemical Societies (FECS). The questimnaires from 45 UK and 2 Turkish institutions were returned after the results for 159 institutions from 20 member countries had already been returned and analysed by WPAC. Institutions were divided into two groups, those with and those without a separate chair of analytical chemistry. When the results for the UK institu- tions were included, the average number of hours spent on all analytical topics fell from 599 to 579 for the former category and from 456 to 367 for the latter category.The UK institutions7 consisted of almost exactly two-thirds university and one third polytechnic chemistry departments. Of these, only 17 were able to identify a person with over-all responsibility for the teaching of analytical chemistry and many indicated difficulty in completing the questionnaire as ana- lytical chemistry was incorporated into areas of organic, inorganic and physical chemistry and thus could not be distinguished as a separate undergraduate discipline. At least 20% of the UK’s professional chemists are employed in analytical work in one capacity or another8 and many vacancies for graduates are, as the advertisement pages of Chemistry in Britain show, analytical in nature.It may thus be important for institutions to demonstrate that their gradu- ates have indeed covered many of the topics necessary to satisfy the requirements of the study guide for entry to the indicative register of analytical chemists. This may not be too difficult, if indeed analytical topics are taught but not co- ordinated as the responses to the FECS questionnaires seemed to suggest. The purpose of this article is to propose a framework within which analytical material may be viewed and thus to enable the analytical content of any undergraduate programme to be regarded as a co-ordinated set of topics. The Underlying Philosophy of Analytical Chemistry Analytical chemistry covers such a wide range of topics and underpins so many areas of science that it is difficult to provide a concise accurate definition for it.However, the underlying major theme is that analytical chemists provide information about the chemical composition of materials in order that a decision may be taken. The over-all analytical method can be considered to be built up of a number of individual stages, as shown in the first line of Fig. 1. Linking each stage in the method is a procedure such as is shown in line two of Fig. 1. The task facing the analytical chemist is to choose the most appropriate procedures in order that the desired information about the particular material of interest can be provided. To be able to do this, the analytical chemist must firstly have a working knowledge of the characteristics of the availableANALYTICAL PROCEEDINGS, JULY 1989, VOL 26 252 Sampling Chemistry Instrument Ca I i bratio n Evaluation or or Line 2.Procedures involved: I Column 1. Dialogue with client a. Object of the exercise? b. One-off or on-going? c. DeterminandIs)? d. Other components? e. Concentrations of c and d? f. What uncertainties can be tolerated? g. What will be done with results? h. Time-scale? i. How much money is available? j. Nature of sample? I Column 2. Test/l nst ru ment perform a nce a. Working range b. Sensitivity c. Detection limit d. Selectivity e. Multi-determinand capability f. Speed g. costs h. Automation i. Amount of sample j. Calibration requirements k. Sample types I Column 3. Resources a. Chemical knowledge b.Personal contacts c. Skills: manipulative c h em om et ri c computing information retrieval/ management communication personnel management d. Continuing education: courses conferencesimeetings literature Line 3. Errors involved: Contributions to overall k term from each procedure? Fig. 1. The analytical chemist at work procedures, and secondly enter into a dialogue with the end-user of the information. This latter activity is necessary to ascertain under what constraints the method must operate, and will involve the topics listed in column 1 in Fig. 1. As the majority of analytical methods involve an instrumental tech- nique it is important that an appropriate one is chosen. The relevant performance criteria are listed in column 2, It may well be that the most appropriate instrument for the method is a burette or balance.Thus, in this view of analytical chemistry, there is no division between the so-called “classical” and “instrumental” methods. All instruments, i . e . , devices which produce a number related to the chemical composition of the pre-treated sample, are considered to be part of the analytical chemist’s range of techniques, whether they are based on the measurement of volume or of mass-to-charge ratio. In addition to a knowledge of the relevant performance criteria of various instrumental techniques, the analytical chemist makes use of a number of other resources in deciding on or devising an analytical method. It has been said that the most efficient method of devising an analytical method for a problem not previously encountered is to telephone someone who has already dealt with the problem.The problem then becomes one of knowing whom to telephone. The role of personal contacts and how they are made (through various continuing education and professional society activities) is not to be underestimated, as the majority of analytical chemists nearing the end of their careers now will be using techniques which did not feature in courses of study 3040 years ago. The final procedure is possibly the most important of all, as without an indication of the reliability of the chemical information produced, no decision should be taken. Line 3 in Fig. 1 summarises the evaluation procedure. In order to assign an uncertainty to a numerical value, usually in the form of a “plus or minus” term, the analytical chemist has to be able to assess the uncertainty of each of the procedures involved in a particular method. This involves a knowledge of sources of random and systematic error and of how they will propagate through the method.Thus, the analytical chemist must be conversant with the appropriate chemometric techniques for the calculation and manipulation of uncertainties. Depicting the analytical method as progress through a sequence of procedures underlines the cumulative effect of the errors involved and the view of this effect as “no chain can be stronger than its weakest link” is readily appreciated. The weakest link may turn out to be a gross blunder, and analytical chemists should be watchful for transpositions (or worse) during calculations.Nothing should be taken for granted, including the concentrations of the standards, and calculations should always be independently checked. In general, in devising and using an analytical method there will be three sorts of decision to be made. The first and second concern the method itself and are decisions about (a) does the method work, i.e., does it meet the requirements of the client, and (6) once in use, is the method performing satisfactorily. Answering these questions requires a knowledge of strategies for method validation and quality control and of the implica- tions in terms of time and cost of the proper implementation of such strategies. Clients are often reluctant to accept the extra costs of good quality control, but the failure to implement properly such procedures has been demonstrated, by manyANALYTICAL PROCEEDINGS, JULY 1989, VOL 26 253 reports in the literature, to lead to large uncertainties in results.A recent example of such a report9 and the subsequent correspondence generated, illustrate these points nicely. It is important to communicate clearly to the customer the conse- quences of skimping on the quality control procedures, namely cheaper analyses but less reliable results. Of course, it is important to use analytical procedures appropriate to the customer’s requirements. The third sort of decision concerns the use to which the chemical information generated is to be put, and again the appropriate chemometric procedures will have to be invoked if a degree of confidence is to be assigned to the correctness of the decision taken.Many analytical chemistry text-books quite properly stress the importance of being able to assess the over-all uncertainty in a method and include discussions of sampling errors, problems of loss and/or contamination during pre-treatment and of various interference effects in instrumental techniques, but ignore the uncertainties introduced by the calibration procedure adopted. Many chemical instruments are calibrated by recording the off-null registrations of the instrument to the concentration of a discrete number of standards. A calibration function is then constructed by a curve-fitting algorithm of some sort. Linear regression procedures for both straight lines and curves and some commonly used micro-computer based methods introduce considerable errors.10,11 The Role of the Instrument Instrumental techniques occupy a central position in the procedures of an analytical method both literally and meta- phorically. In order to be able to assess the suitability of a technique for a particular method, according to the criteria set out in column 2 in Fig. 1, to adopt appropriate pre-treatment and calibration procedures and to be able to assess the instrument’s contribution to the over-all uncertainty, it is necessary for the analytical chemist to understand how the instruments work. Most chemical instruments can be con- sidered to consist of the internal functions, shown in Fig. 2, that are seen when the “lid is taken off the black box.” ‘ Pre-treated Sample + sample - ------ r Chemical I information- i T i Sample introduction Number -Chemistry- Transducer- Electronics I 1 t----l L I Operating parameters 1 I Fig.2. Taking the lid off the black box There are two main functions inside the instrument, chem- ical and electronic. These interface at the transducer, the device which converts information in the chemical and physical domains into information in the electrical domain. The analytical chemist needs to know how the transducer works, how reliable it is, what factors affect its reliability as well as what is done to the electrical signal before it appears as a number in the digital domain. Some instruments, of course, are not designed to produce a single piece of information in the digital domain but to record the variation of signal (analogue or digital) level with time (which may be related to some other physical parameter, such as wavelength).In this latter instance, the conversion of the instrument output to chemical information will involve interpretation rather than calibration; for example, the success of a partial elucidation of a molecular structure by infrared absorption spectrometry depends on the accuracy with which the wavenumbers and relative intensities of various peaks in the spectrum may be assigned. It is also important that, to avoid the introduction of easily avoidable errors, the analytical chemist knows how changes in the operating parameters affect the working of the instrument. The Role of Chemistry It can be seen from Fig. 1 (line 2) and Fig.2 that chemistry occurs in a number of distinct locations. Firstly, it is bound up with the sampling procedure. A knowledge of the chemical properties of the determinands and of the other components of the bulk material is necessary if an appropriate sampling procedure is to be devised. Secondly, a wide variety of chemical procedures are involved in pre-treatment : these range from preservation or fixing at the scene of sampling, through dissolution, pre-concentration and matrix isolation, to the addition of appropriate reagents. Most of the latter procedures are performed on the bench in the laboratory. It should be noted that a sample which arrives in a laboratory for analysis will probably be sub-sampled before the method continues. The third location of chemistry in an analytical method is inside the instrument. Many instrumental techniques in use in laboratories today perform extensive chemistry on the sample components.Consider, for example, the internal processes of an atomic absorption spectrometer or a gas - liquid chromato- graph. A knowledge of chemistry is required to understand the basis of a number of interference effects and to compensate for these by the design of appropriate instrument operating conditions or calibration procedures. Many interpretation problems concern interpretation of “chemical shifts.” This terminology is widely used in, for example, nuclear magnetic resonance and X-ray photoelectron spectroscopies, but the same principle is involved in interpreta- tion of the results produced by molecular ultraviolet - visible absorption, fluorescence and infrared absorption spectro- metries.In these techniques, no chemical reactions occur inside the instrument as part of its basic operation, but the chemical nature of the sample material influences the behav- iour of the transducer. In some techniques the transducer converts information directly from the chemical domain into the electrical domain as, for example, with ion-sensitive electrodes. Throughout the method, up to the point at which the information required is encoded as an electrical signal, chemistry is involved in assessing the risks of contamination of the sample material, either with the determinand species or interfering species, and a loss of the determinand species. f i e r e is thus no diminution in the amount of chemistry in analytical chemistry, and scientists who wish to pursue a career in this area must have a substantial chemical education (arguably to degree level).Developments in instrumentation have meant that chemistry is performed in locations other than reaction vessels on the laboratory bench, but this has not decreased the requirement for chemical knowledge. Role of Sampling Although it is widely recognised that providing a representa- tive sample from a bulk material for laboratory analysis is not a trivial problem,l* and that errors introduced at this stage cannot be compensated for later on, it is often overlooked that the material for analysis may be sub-sampled several times before the chemical information is encoded in the electrical domain.Take, for example, the analysis of a solid material for254 ANALYTICAL PROCEEDINGS, JULY 1989, VOL 26 a trace element by a method which uses flame atomic absorption spectrometry as the instrumental technique. Once the material for analysis has arrived in the laboratory a sub-sample will be dissolved, a further sub-sample may be taken for pre-treatment and a further sub-sample loaded into a cup in the auto-sampler tray. The auto-sampler selects a sub-sample, which is further sub-sampled by the nebuliser and spray chamber. As the beam of radiation from the hollow cathode lamp passes through a restricted volume of the flame, the resulting population of vapour phase species is further sub-sampled before the photomultiplier tube converts light intensity into electrical current.It should also be borne in mind that sampling is very much part of electrical signal processing. Inappropriate sampling in, for example, analogue to digital conversion procedures, can give rise to problems of aliasing if a regular waveform is being sampled, or errors in peak height and peak area measure- ments, if single transient events are being monitored. Practice, Teaching and Research and Development Fig. 1 summarises the practice of analytical chemistry and it might be argued that, as many scientists make use of information provided by analytical chemists, all scientists should be aware of the contents of Fig. 1 and, in particular, of the constraints under which analytical chemists operate. It is also necessary for such scientists to appreciate why information will be qualified by a statement about its reliability, that uncertainties can be large and that the reduction of uncertainty can be an expensive and time-consuming business.Chemistry students who will possibly enter employment as analytical chemists need not only to appreciate the underlying philosophy of Fig. 1 but to have the appropriate knowledge and skills outlined in column 3 (Fig. l), as well as a knowledge of instrument performance criteria (column 2, Fig. 1) and of instrument function as illustrated in Fig. 2. Research and development in analytical chemistry may be viewed as efforts to improve the performance of analytical methods by improving the performance of the various pro- cedures involved. The criteria set out in column 2 of Fig.1 provide a suitable check-list against which to evaluate the success of such efforts. At present many such efforts are being directed at extending the boundaries of the instrument, as shown by the dotted lines in Fig. 1, so that (a) sample pre-treatment procedures are carried out within the instrument (ideally they would be rendered redundant by developments in internal chemistry and transducer function), and (6) evaluation and calibration procedures are part of the instrument function. The latter development means that it is increasingly im- portant that analytical chemists (or anyone who uses such an instrument) have the necessary knowledge of how the instru- ment has produced its chemical information in order to assess its reliability.These are the views of an academic, but it is time that employers of analytical chemists made their views of training requirements known. 1. 2. 3. 4. 5. 6 . 7. 8. 9. 10. 11. 12. References “Supply of and Demand for Analytical Chemists. Report of an Investigation by a Working Party of the Royal Institute of Chemistry,” Royal Society of Chemistry, London. July, 1980. Royal Society of Chemistry Professional Bulletin, Nu. 80, December, 1985. Royal Society of Chemistry ProfessionaL Bulletin, No. 82, July, 1986. ACOL Project Office, Thames Polytechnic, Wellington Street, Woolwich, London SE18 6PF. Tyson, J. F., Anal. Proc., 1988, 25, 11 1. Kellner, R., and Pungor. E., Trends Anal. Chem., 1985, 4, v . In the UK, the survey was co-ordinated by the Education and Training Group of the Analytical Division of the RSC.The Honorary Secretary, Dr. L. A. Gifford, provided a brief analysis of the UK returns at a committee meeting in September, 1985. “Remuneration Survey, 1986,” Royal Society of Chemistry, London, 1986. Sherlock, J . C., Evans, W. H., Hislop, J . , Kay, J. J., Law, R., McWeeny, D. J., Smart, G. A., Topping, G., and Wood, R., Chem. Br., 1985, 21, 1019. Miller, J. C., and Miller. J. N., “Statistics for Analytical Chemistry,” Second edition, Ellis Horwood, Chichester, 1988, Bysouth, S. K., and Tyson. J. F., J. Anal. At. Specfrom., 1986, 1, 63. Smith, R., and James, G. V., “The Sampling of Bulk Materials,” Royal Society of Chemistry, London, 1981. pp. 102-115. ROYAL SOCIETY OF CHEMISTRY: ANALYTICAL DIVISION ATOMIC SPECTROSCOPY AND CHEMOMETRIC GROUPS AND SOUTH EAST REGION A Meeting on CALIBRATION AND OPTlMlSATlON IN ATOMIC SPECTROSCOPY will be held in Thames Polytechnic, Woolwich on November Ist, 1989 The papers given at this Joint Meeting will be as follows: “Advances in Monte Carlo Modelling of Processes in Graphite Furnace Atomic Absorption Spectrometry,” by W. Wegscheider; ”Possibilities for Automated Method Development in Analytical Atomic Spectrometry Using Expert Systems,” by J. Carroll; ”Solutions to Spectrum Processing and Quantitative Calibration Problems in Energy Dispersive XRF Spectrometry,” by A. T. Ellis; ”Computerised Tomography-Its Use in Atomic Spectrometry,” by S. J. Hill and L. Ebdon; and ”Atomic Spectrometry and Chemometrics-The Dynamic Duo,” by M. Thompson. Registration is necessary. The registration fee is €35 for members of the RSC, f60 for non-members and f5 for students, unemployed and retired members of the RSC. For further information contact Dr. J. R. Dean, Department of Chemical and Life Sciences, Newcastle upon Tyne Polytechnic, Ellison Building, Newcastle upon Tyne NEI 8ST.

ISSN:0144-557X    

DOI:10.1039/AP9892600251

出版商:RSC    

年代:1989

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS. JULY 1989, VO1 26 255 Fourth Biennial National Atomic Spectroscopy Symposium The following are summaries of three of the papers presented at a Joint Meeting of the Atomic Spectroscopy Group and the Spectroscopy Group of the Institute of Physics held from June 29th to July lst, 1988, in the University of York. Twenty-four other papers appeared in full in the March issue of the Journal of Analytical Atomic Spectrometry. Use of the Hydride Generation Technique in the Determination of Bismuth with a d.c. Plasma Atomic Emission Spectrometer Paavo Peramski, Veli Matti Korvala and Lauri H. J. Lajunen Department of Chemistry, University of Oulu, SF-90570 Oulu, Finland The use of the hydride generation technique, together with various atomic spectrometric methods (atomic absorption, atomic emission and atomic fluorescence), has established its position in the determination of trace amounts of germanium, tin, lead, arsenic, antimony, bismuth, selenium and tellurium.1 Applications of the hydride generation method in connec- tion with a direct current plasma atomic emission spectrometer (DCP-AES) are not so numerous, however. The original work was done by Miyazaki et a l . , who determined arsenic and antimony in water samples with a batch-type hydride genera- tor. In their system the evolved hydrides were first collected in a liquid nitrogen trap.' Other uses of batch-type systems are the determination of selenium and tellurium3 and arsenic4 in aqueous solutions and germanium in ferrous dust.5 The determination of antimony in geological samples has also been reported.6 A batch type hydride generator is a simple piece of instrumentation, but a continuous-flow hydride generation system offers some advantages in contrast to a batch-type system, e .g . , the possibility of emission signal integration. Panaro and Krull used a continuous flow hydride generation method for the determination of arsenic in water and fish samples.' Krull and Panaro also interfaced a high-performance liquid chromatograph with a continuous flow hydride genera- tion DCP-AES for the determination of total tin and organotin compounds.8 Further, Ek and Hulden investigated the deter- mination of arsenic and selenium9 and Ebdon and Sparkes determined selenium in environmental samples with a continu- ous flow hydride generation DCP-AES.l o In this work bismuth was determined with a batch type hydride generator coupled to a DCP-AES. The method was applied to the determination of bismuth in geological reference samples. Experimental Instrumentation Bismuth emission signals were measured by use of a Spectra- Span IIIB single channel d:c. plasma atomic emission spec- trometer. A Hewlett-Packard 85 processor, interfaced with the spectrometer, was used for data processing when samples were introduced by pneumatic nebulisation. In the hydride genera- tion method emission signals were recorded by a Goertz 120E chart recorder. The peak heights were also read from the digital display of the spectrometer. The instrumental settings used in the measurements are given in Table 1.~~~~ ~ ~ Table 1. Instrumcntal parameters for determination of bismuth Sample introduction Equipment Hydride generation Nebulisation Spectromerer- Wavclengt h/nm 223.031 223.031,289.798 298.903.306.772 Entrance slit/pm 100.300 100. 300 Exit slit/pm loo. 300 100, 300 Ncbuliser pressurefib in-' 14 20 Integration time/s Active diagnostic 5 , lot Repeats 3.9t Sample volume/ml 10 Sample acidity. YO 5 NaBHl volume/ml 0.5 NaBH., concentration. YO m/V 2 .o Argon flow/l min- 1.5 Reaction time/s None PMT voltageN 800 * Gain 12 * Sleevc pressure/lb in-' 50 50 mode Hydride generutor- Recorder- Sensitivit y/mV 20-100 Chart speedcm min- * 0.5 * Variable settings were used. t Determination of background equivalent concentration and detec- tion limit. Reagents Only analytical-grade reagents were used. The reagents were obtained from Merck, except sodium tetrahydroborate, which was obtained from Fluka AG.The water used was demineral- ised and distilled. A stock solution containing 1000 mg 1-1 of bismuth was prepared by dissolving 1.oooO g of bismuth metal in 50 ml of concentrated nitric acid and diluting the solution to 1000 ml with distilled water. Other stock solutions, containing lo00 mg 1-1 of each element, were prepared from the following reagents: iron, germanium, tin, antimony, selenium and tellurium (metallic elements), nickel(I1) chloride hexahydrate, copper(1) nitrate trihydrate and lead(I1) nitrate. A reductant solution was prepared by dissolving sodium tetrahydroborate in distilled water. The solution was stabilised by adding one sodium hydroxide pellet (approximate mass about 200 mg) per 50 ml of solution.A fresh solution was prepared daily.256 ANALYTICAL PROCEEDINGS. JULY 1989. VOL 26 Procedures Solution nebulisation When characteristics for different wavelengths were measured, solutions were made up in 1% nitric acid and the sample uptake rate during nebulisation was 1.6 ml min-1. The different plasma positions (although they could not be precisely calib- rated) were defined as follows. The position where the entrance slit was just placed inside the excitation region (crook of the “V”) was defined as “-1”. Then the vertical control knob of the jet assembly was turned counter-clockwise, one turn giving the position “0” and two turns “+l”. 110 1 22 2% NaBH, 4% NaBH, Y g 90 1% NaBH, \+ a %loo- -..- r“ Y I-\<\% a 70 \ 3% NaBH, 1 2 4 6 8 10 12 14 Reaction time/s 6o 0 Fig. 1. (reductant volume 0.5 ml) The effect of reaction time on the determination of bismuth Hydride generation In the measurements made with the hydride generation procedure samples were dissolved in 5% hydrochloric acid, which is a suitable medium for hydride generation with bismuth.11,12 During the optimisation procedure, and in interference studies, the bismuth concentration in test solu- tions was 30 pg 1-1. Dilute solutions were always prepared just before use. The hydride generation system has been described else- where.3.h However, a slightly modified system was used in the determination of bismuth. The drying and delaying tubes of the hydride generator were removed and only a cotton wool plug was placed in the outlet tube of the generator.The measure- ment procedure was essentially the same as described in reference 6, except that a 2% (mlv) reductant solu” lion was used instead of a 4% solution. Also, the bismuth hydride was swept into the plasma immediately after the addition of reductant, without any collection time. Digestion of geological samples Reference samples were accurately weighed (0.2 g) into 100-ml beakers. Six millilitres of aqua regia were added and the beakers covered with watch glasses. The beakers were next put in a sand-bath for 1.5 h ( t = 120°C). Then the samples were allowed to cool and they were diluted with water and centrifuged. The solutions were transferred to 100-ml calib- rated flasks and diluted to volume with 5% hydrochloric acid.Table 2. Signal to noise ratios for different bismuth wavelengths* Wavelength/nm Plasma position S:N ratio 223.031 + 1/2 23.0 289.798 + 1/2 14.5 298.903 0 16.4 306.772 - 1/2 6.8 * Analytical solution contained 100 mg 1-l of bismuth. Finally, the solutions were further diluted, and the analysis were made by a standard addition method. Results and Discussion Pneumatic Nebulisation Four different wavelengthsl3 for bismuth were studied in detail (Tables 2 and 3). Although the emission line at 306.772 nm was very sensitive, it had a poor signal to noise ratio. Therefore, the emission wavelength 223.031 nm, which gave the best detec- tion limit, was selected for further use with the hydride generation met hod. 4 - 3.5 - 3.0 - 2.5 8 a - 2.0 $ - 1.5 - 1.0 - 0.5 L 1 I ’0 0 2 4 Red u ct a n t concentration , O/O Fig.2. The effect of reductant concentration in the bismuth determination (no reaction time, VNaBHJ = 0.5 ml) Hydride Generation Op tim isation The hydride generation for bismuth was first tried with the original SpectraMetrics hydride generator,3 but no bismuth emission signal was obtained. This was presumably a result of (thermal) instability* of the bismuth hydride formed’s (the same phenomenon has already been observed with tel- lurium3.16). Bismuthine is easily decomposed when it is swept through the drying and delaying tubes of the generator. Therefore, these tubes were removed and the bismuth hydride was purged directly into the plasma from the reaction vessel. When the hydrogen delaying tube is removed, extra care must be paid to the problems associated with the hydrogen that * The drying tube becomes hot when it absorbs water from t h e gas mixture.Table 3. Analytical characteristics for different bismuth emission lines measured by DCP-AES* Background Relative equivalent Detection Linear dynamic Wavelengt h/nm sensitivity concentratiodmg I- 1 limitlmg I- 1 range/mg I- I 223.031 0.11 2.644 0.056 0-100 289.798 0.04 5.294 0.116 O-lOOO 298.903 0.04 3.690 0.477 0-1o00 306.772 1 11.90 0.359 0-100 * The determinations were made according to procedures described in reference 14.ANALYTICAL PROCEEDINGS. JULY IYXY. VOL 26 5000 v) +- 5 4000 0 KJI 3000 -.. 2 .- Q) r 257 - - - Table 4. Results of the determination of bismuth in the reference samples (results in mg kg-1) This work Sample Material Individual result* Mean A B C GXR- 1 Jasperoid 14-46 1870 k 258 1700 > 100 1725 1876 1879 2037 2111 GXR-4 Copper mill 16.12 22.2 t 5.2 9 22 21.2 heads 1Y.Y7 22.12 22.58 30.37 D 1640 20 * Each value represents different weighting and determination. A.HCI digestion. MIBK extraction. FAAS.l‘’.’” B. Sodium hydrogen sulphate fusion, MIBK extraction, GFAAS.‘O C. KC103 - HCI digestion. MIBK extraction. FAAS.” D. HCI - Hz02 digestion, MIBK extraction, FAAS.” is a by-product in the reaction. A cotton wool plug was inserted in the outlet tube of the generator in order to damp the pressure wave generated. I t was also decided to purge the hydride immediately into the plasma after addition of the reductant so as to keep the hydrogen production to a minimum (Fig.1). A 4% sodium tetrahydroborate reductant solution used earlier3.6 was not suitable on this occasion, because the hydrogen was disturbing the plasma. Therefore, 0.5 ml of 2% reductant solution, giving satisfactory reproducibility for bis- muth hydride generation, was selected for use (Figs. 2 and 3). 120 I 1 8 0 0.2 0.4 0.6 0.8 1 .o Reductant volurne/rnl Fig. 3. bismuth ( CNaBH4 = 2%. no reaction time) The effect of reductant volume on the determination of The effect of argon flow through the reaction cell was also investigated. The best sensitivity was obtained when the flow was about 1.5 1 min-1 (this value was also used in the optimisation procedure). If the argon flow was higher, the plasma became unstable. When the nebuliser pressure was varied and argon flow through the cell kept constant (1.5 1 min-1).the best net signal to noise ratio was obtained at value 14 Ib in-’. The calibration graph for bismuth was linear up to 70 pg 1-1 (Fig. 4). A detection limit of 0.99 ng in a 10-mI sample was obtained (calculations were based on the mean of the blank plus three times its standard deviation, IZ = 10). The RSDs of the method were 2.2 and 1.5% for solutions containing 3 and 30 pg 1-1 of bismuth, respectively (n = 10). The matrix ion effects As a continuation of earlier studies,3.6 the interference effects of the other hydride forming elements and also iron, nickel and copper on the bismuth determinations were investigated. The bismuth concentration in test solutions was 30 pg 1 - 1 and increasing amounts of the other elements (one at a time) were added. As can be seen in Fig.5 , selenium, tellurium and copper interfaced at higher concentrations in the range studied. The interference effects caused by selenium and tellurium were similar to the effects of these elements on the determination of antimony.h Including the interferences of bismuth on the determination of selenium, tellurium and antimony,3.6 the interference effects seem to associate with the fact that at high concentrations bismuth, selenium and tellurium are reduced to free metals or perhaps metal borides” in the reaction vessel during the reduction step. However, the formation of a dark precipitate in the reaction vessel was not seen at this time. The interference effect caused by copper is obviously due to the formation of an inter-element compound with bismuth.6000 r :IlL-- 0 20 40 Bisrnuthipg 60 80 I - 100 120 140 Fig. 4. Calibration graph for bismuth Determination of Bismuth in Geological Samples Bismuth was determined in US Geological Survey reference samples GXR-1 and GXR-4.t The analyses were made by a standard additions method, because interferences were expec- ted in a complex sample matrix (the effects of the other elements can be diminished by using various masking agents, as reviewed by Nakaharal.18). The results of the determinations are shown in Table 4. The variations between individual results ~ ~~ t. The analysis of samples GXR-2 and GXR-5 (soil samples) was also tried. Because thcse materials contained very low levels of bismuth. one gram of each material was weighed.However. the solutions could not be diluted sufficiently and. when analysis from the concentrated solutions was attempted. large amounts of gas were produced. extinguishing the plasma. This problem could probably have becn overcome by evaporating the samples to dryness and re-dissolving the residue.258 a a .- G 40 a - a 20 ANALYTICAL PROCEEDINGS. JULY 1989. VOL 26 - - O 1 2 4 Molar ratio of interferent analyte zot bcu I /I I 1 10 20 40 100 200 0 1 . r ’ 1 2 4 Molar ratio of interferent analyte Fig. 5. bismuth The effect of the other elements on the determination ot are quite large, but the mean values are satisfactory in comparison with other published values. Conclusions The instability of bismuth hydride creates specific require- ments for hydride generator design, as is observed in this work. When the hydrogen delaying tube is removed, hydrogen causes problems with a d.c. plasma.These difficulties may, however, be overcome by careful adjustment of instrumental paramcters and solution concentrations. When bismuthine is swept directly into the plasma, the sensitivity is improved, as long as the quantification is based on measurement of the peak height. However, the linear dynamic range of the method is dimin- ished. In conclusion, the proposed method proved to be a suitable way of monitoring bismuth at low levels, as indicated by the results obtained from the GXR samples. 1. 2. 3 . 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19.20. 21. 22. References Nakahara. T., Prog. Anal. Atom. Specrrosc.. 1983, 6. 163. Miyazaki. A.. Kimura. A., and Umezaki, Y., Anal. Chim Acra. 1977. 90. 119. Hayrynen, H.. Lajunen. L. H. J.. and Peramaki. P.. Arorn. Specrrosc.. 1985.6. 88. Boampong, C.. Brindle, I . D.. and Ponzoni, C. M. C., J. Anal. Afom. Specfrom., 1987. 2. 197. Brindle. I. D.. and Ponzoni. C. M. C.. Analysr. 1987. 112. 1547. Peramaki. P.. and Lajunen. L. H. J.. Anul.yst. 1988. 113. 1567. Panaro. K. W.. and Krull. 1. S.. Anal. Lerr.. 1984. 17. 157. Krull. I. S., and Panaro. K. W.. Appl. Specrrosc.. 1985, 39. 960. Ek, P.. and Hulden. S.-G.. Talanra. 1987. 34. 495. Ebdon. L., and Sparkes. S. T.. Microchem. J . . 1987. 36. 198. Fernandez. F. J.. Atom. Ahsorpr. Newsl.. 1973, 12. 93. Thompson. M..Pahlavanpour. B.. Walton. S. J.. and Kirk- bright. G. F., Analyst. 1978. 103. 568. Meggers. W. F.. Corliss. C. H.. and Scribner. B. F.. “Tables of Spectral Line Intensities. Part 1-Arranged by Elements.” Second Edition. U.S. Government Printing Office. Washing- ton. 1975 (reprinted by SpectraMetrics). “Handbook of Spectral Line Characteristics for thc DC PlasmdEchelle Systems.” SpectraMetrics. Andovcr. MA, USA. Fujita. K.. and Takada. T.. Tulanfa. 1986. 33, 203. Chapman, J. F., and Dale, I. S., Anal. Chim. Acfa, 1979. 111, 137. Bye. R.. Talanra, 1986. 33. 705. Nakahara. T.. Nakanishi. K.. and Wasa. T.. Spectrochim. Acra, 1987.42B. 119. Headridge. J . B.. and Richardson. J.. Analysr. 1970. 95, 930. Ficklin. W. H.. and Ward, F. N., U.S. Geol. S u n ) . J . Res.. 1976.4, 217. Viets. J. G.. Anal. Cliem.. 1978, 50. 1097. O’Leary. R. M., and V i m , J . G.. Arorn. Spectrosc.. 1986.7.4. Improvement in the Determination of Bismuth by Flame Atomic Absorption Spectrometry Using a New Design of Slotted Tube Atom Trap Narong Chimpalee, Michael Harriott and D. Thorburn Burns Department of Pure and Applied Chemistry, The Queen‘s University of Belfast, Belfast BT9 5AG, Northern Ireland The use of a slotted quartz tube as an atom trap in flame spectroscopy was first described by Watling. 1-3 The system has since been studied in a commercial format (STAT, slotted tube atom trap) by Brown et d.4-8 The elements that showed sensitivity improvements were volatile and formed compounds which decomposed thermally in the primary reaction zone of an air - acetylene flame.The improved sensitivity using a STAT was attributed to reduced flame speed, a longer optical path and the partial exclusion of the entrained air. This produces a stable chemical environment and enhanced concen- tration of neutral atoms. This system has been studied by using different tube designs to obtain the best sensitivities for bismuth. Experimental Apparatus A Perkin-Elmer Model 403 atomic-absorption spectropho- tometer was used with a Perkin-Elmer bismuth hollow cathode lamp. Signals were recorded using a Perkin-Elmer Model 56 chart recorder set at the 10-mV range. The spectrometer conditions for bismuth were: wavelength, 223.1 nm; lamp current, 10 mA; band-pass, 0.7 nm; flame, lean air - acetylene; aspiration rate, 5.6 ml min-1.A cradle similar to that of Brown and Taylor5 was built to align the slotted tube directly above the burner head slot along the instrument’s optical path (Fig. 1). The cradle is attached toANALYTICAL PROCEEDINGS, JULY 1989. VOL 26 259 Table 2. Sensitivity for bismuth with the various STATs Fig. 1. STAT and cradle the burner head by using the two burner safety wire retention screws; the slotted tube is held in place on two V-shaped adjustable plates on the loading arm by springs. The design allows a change over from analysis by STAT to that by conventional flame in seconds. The various STAT designs examined are described in Table 1. Table 1. Slotted tube atom trap designs STAT Tube material, dimensions and entrance slot A STAT tubes (A-E) were of B translucent quartz, 140 mm C long, 15 mm i.d.Entrance D slot, 115 mrn X 3 mm wide E I in each instance Exit at 180" to entrance slot, dimensions 1lOmm x 3 mm 90 rnm x 3 mm 50 mrn x 3 mm 30mrn x 3mm STAT E contained a row of 8 holes, 6 mm diameter, 9 mm apart 100mm x 3mrn 90mrnx3mm 50mrn x 3mm 30mmx3mm STAT J contained a row of 6 holes. 6 rnm diameter, 9 rnm apart Reagents All acids and salts used in the interference studies were of AnalaR grade (BDH Chemicals). Trace element stock solution was supplied by BDH Chemicals as 1000 mg 1-1 solution (SpectrosoL). All water used was doubly purified by distilla- tion followed by de-ionisation (Egla C114). Quartz tubes. Satin surface translucent and transparent grades from Thermal Syndicate. Results and Discussion Optimisation and Interference Study The position of the STAT relative to flame was varied by means of the V-ended adjustable plates.The STAT was adjusted in relation to the spectrometer's optical axis by means of the normal lateral and vertical burner position adjustment controls. The highest signals were obtained for STAT A-E with 10-mm gap between the burner head and the bottom of the STAT and for STAT F-J with an 8-mm gap. An enhancement of the bismuth absorbance signal com- pared with that given by the flame was obtained with all STAT tubes (Table 2 ) . The greatest enhancement was with STAT design I; however, because of the length of the tube and the STAT A B C D E F G H I J Flame alone Sensitivity*/pg ml- 1 0.34 0.27 0.26 0.25 0.27 0.30 0.26 0.26 0.24 0.25 0.50 * Concentration to give absorbance of 0.0044 small exit slot the flame deposited material on the spectrometer windows.Designs D and J gave the next highest responses, but the use of D also caused damage to the spectrometer windows. STAT design J was the best compromise between enhance- ment of signal and avoidance of deposition of material on to the spectrometer windows. After coating with lanthanum oxide the STAT tubes were able to withstand prolonged use. Devitrification, spreading outwards from the slots or holes, limited the tube lifetimes to about 300 discrete samples sprayed and measured. Linear calibration graphs were obtained for bismuth stan- dards (in 2% V/V nitric acid) over the concentration ranges 0-10 pg ml-1 (Fig. 2). The enhancement factor for STAT versus flame at the optimum observation height was ~ 2 .2 . The sensitivity, detection limits and precision data are as follows: sensitivity, 0.25 pg ml-* (= 0.0044 absorbance); detection limit, 0.143 pg ml-1 (= 2~ base-line noise); precision, 0.8% (rsd for 10 replicates at 4.0 pg ml-1). 60 1 Concentration of bismuth, p.p.m. Fig. 2. Calibration graph for bismuth. Enhancement factor = 2.2 An interference study was carried out on 4 pg ml-1 of bismuth for the elements expected (calcium, magnesium, sodium and zinc ions) over concentration ranges for calcium and magnesium of up to 500 pg ml-1 and for sodium and zinc of up to 1000 pg ml-1, exceeding the concentrations found in pharmaceutical formulations. The results showed no signifi- cant interferences. However, devitrification of the tube was observed, as noted by Brown and T a y l ~ r , ~ and this was caused by the presence of a high concentration of sodium in the formulations.In order to prolong the STAT tube lifetime, the surface was coated with lanthanum oxide by continuous aspiration of 1% m/V lanthanum chloride solution for 15 min. Analysis of Pharmaceutical Formulations Samples were placed in 100-ml Kjeldahl flasks and 72% perchloric acid and 30% hydrogen peroxide were added. TheANALYTICAL PROCEEDINGS. JULY 1989. VOL 26 260 Table 3. Analysis of selected bismuth containing pharmaceutical formulations Bismuth found/mg Declared bismuth Spectro- Sample con t en t/mg STAT* Flame* photomct rict Bismuth carbonate Bismuth carbonate Bismuth subgallate ointment ( 1 .(K) g ) 19 .x3 19.46 2 0.13 lY.65 f 0.39 19.75 2 0.3') tablet ( 1 tablet) 10.65 11 .O() f 0.07 11.21 * 0.20 10.91 * 0.10 suspension ( 1 ml) 49.17 50.45 f 0.32 52.24 k 0.72 5 1 .ox * 0.06 * Each value is the mcan and standard deviation for 1 0 analyses.t Each value is the mcan and standard deviation of 5 analyses. mixtures were heated gently to complete oxidation and placed (filtered if necessary) into 1 0 ml calibrated flasks and made up to volume with distilled water. Sample solutions were then diluted with 2% ( V / V ) nitric acid to bring them within range of the calibration graph. Results and Conclusions The results for the pharmaceutical formulations by STAT and conventional flame atomic absorption spectrophotometry arc given in Table 3. The formulations were also analysed independently by an ultraviolet - visible spectrophotometric method," the results being in good agreement with those obtained by STAT.With the use of STAT it is possible to determine bismuth with aqueous standard solutions. Results obtained by using a conventional flame system show a slight systematic positive bias compared with those by STAT. The precision attained using STAT was superior to that attained from the conventional flame system. The method described herein is thus considered suitable for the routine determination of bismuth in pharmaceutical formulations. 1. 3. 3. 4. 3. 6 . 7. 8 . 9. References Watling. R. J . . Atzul. Chitn. Actu, 1977. 94. 181. Watling. R. J .. Atiul. C'hitn. Actu, 1978. 97. 395. Watling. R. J . . and Watling. H. R.. Spctrodzitn.Actu, 1980. 35B. 451. Taylor. A . , and Brown. A. A.. Anulyst, 1983. 108. 1159. Brown. A. A.. and Taylor. A.. AtzuIysta 1984. 109. 1455. Brown. A. A.. Milner. B. A.. and Taylor, A.. Atiulyst, 1985, 110. 510. Brown. A. A.. and Taylor. A.. Atznly.\t, 1985. 110. 579. Lee, M.. Brohn. A. A.. and Lcfort. C.. Bioj ( N u n c y ) , 1985. 16. 31. Burns, D. T.. and Tungkananuruk. N.. And. C'hitn. Acrtr. 1987. 285. 197. Use of Surface Coatings in the Determination of Bis(tributy1tin) Oxide in Freshwater by Using Graphite Furnace Atomic Absorption Spectrometry C. Donaghy, M. Harriott and D. Thorburn Burns Department of Pure and Applied Chemistry, The Queens University of Belfast, Belfast BT9 5AG, Northern ire Ian d The rate of generation of the atomic vapour of tin from a graphite surface is a complex function of: surface temperature; the rate of temperature increase; and the physical and chemical nature of the surface.1.' These variations, coupled with the possibility of tin being in some molecular form rather than an atomic cloud, have led to the experimental development of graphite surface treatments.Instrumentation All impregnation studies were carried out with a Perkin-Elmer double-beam atomic absorption spectrophotometer (Model 403) in conjunction with the flameless atomisation device HGA76. The measurements were made with a hollow cathode lamp at the 286.3 nm resonance line with a band width of 0.7 nm. The signals were recorded on a Philips PM8251 chart recorder at 10-mV range. The optimised furnace programme Table 1.Furnace programme conditions Dry Ash Atomisc Cleanout Temperature 150°C 800 "C 3500 "C 200 "C Gas-stop 0 f f Off On Off Time 30 s 30 s -.. ' 5 s 5 s conditions for the atomisation of tin and organotin compounds are given in Table 1. Graphite Surface Treatments A range of metal salts were impregnated on to the graphite surface in order to improve the atomisation efficiency of tin.3 The impregnation method was simply the application of a 10% suspension of a metal salt on to the graphite surface using a BCL 1OO-pl micropipette. This procedure, plus the heating cycle in Table 2, was applied six times in order to give a durable surface coating. Table 2. The heating cycle Step Temperature Time 1 Drying 1 50 "C 60 s 2 Ashing 1 (MU) "C 30 s 3 Atomise 4 Cleanout 2(WX! "C 5 s 26" "C 1 0 s (GS) Standard calibration graphs, Fig.1. for tributyltin oxide, using different impregnated surfaces, were obtained by inject- ing SO yl of each standard solution on to each surface. The most effective metal salts were NH4V03,Ta205 and.4NALYTICAl. PKOCEEDINGS. JULY IYSY. VOL 26 26 1 0.75 7 1 a 0.5 e n <0.25 u C m m U 0.1 0.2 0.3 0.4 0.5 0.6 TBTO, p.p.m. Fig. 1. Calibration graphs ( NHl),Mo7021.3H20. In contrast, thc surface NHJVOl showed a much better long-tcrm stability with enhanced sensitivity, without any significant degradation in prccision. A statistical analysis of the results obtaincd using thesc surface matcrials is given in Tablc 3. Atomisation Profile Comparison Initial studies on the atomisation bchaviour of tin in the graphite furnace as a function of timc, as shown in Fig.2. rcvealed very little scnsitivity and poor precision. v h-.. - Ta I 1 Uncoated 1 t Time (300 mm min-1) Fig. 2. Atomisation profilcs This was attributed to the fact that tin forms a carbidc stable enough to slow down considerably the mass transfer of thc clement to the gaseous phase, even at thc highcst operating temperature of the furnace. Thus, a competitive rcaction for the available free carbon sites on the surface of the graphite tube might improvc the atomisation. A selection of transition metal salts as competitors in the formation of stable carbides were therefore screened. The solutions containing molyb- denum. vanadium and tantalum gave positive results in thcse scrccning cxperimcnts. The best over-all sensitivity and precision were obtained with tubes impregnated with vana- dium. Irish Sea Belfast River Land over 120 m Built-up area Strangford Lough - Key:- organotin Sn4+ 200 “c 100 v) 0 l- m I- 50 L 0 Seawater Estuarine Water Site No. 2 Site No.1 Fig. 3. Biological survey Solvent Extraction and Recoveries using a Vanadium Coated Tube The extraction, determination and speciation of tributyltin in seawater is based on the solvent extraction of organotin species directly into toluene and of inorganic tin as its tin(1V) - quinolin-8-01 chelate into chloroform. Thc detection limit was 10-12 ng with 00-100% recoveries.J.5 However, this concentra- tion - separation procedure, when applied to freshwater estua- rine samples. is hindered by the emulsification of the toluene in the aqueous layer.Recoveries are poor and strong interfer- ences occur in the graphite furnace AAS analysis. However, this emulsified layer can be greatly reduced by the addition of 20 ml of 2.5% analytical-reagent grade sodium chloride and 2 ml of methanol to the extract and centrifugation for 15-20 min at 3000 rev min-1. This procedure produces a clear toluene layer, removes graphite furnace interferences and gives 97- 98% organotin recoveries. Environmental Application There is currently considerablc interest in the monitoring andANALYTICAL PROCEEDINGS. JULY 1989. VOL 26 262 Table 3. Statistical analysis Increase in Detection R.S.D.. peak height. limitl Coating n X S.D. YO O/O I% None 5 72.6 2.32 3.19 Nil 6.0 NHJVO~ Ta205 5 108.1 1.64 1.52 50 5.2 ( N H J ) , , M O ~ O ~ J .~ H ~ O 5 121.4 3.14 2.59 70 4.5 5 150.0 1.82 1.21 100 3.0 impact assessment of tin and organotin compounds on aquatic systems. However, there are problems in the determination of these compounds: uncomplexed inorganic salts hydrolyse very rapidly in water; the solubility of inorganic tin is less than 1-2 p.p.m. over the pH range of 2-8; organotin compounds have a very low solubility in water, of the order of 5-100 p.p.m. Therefore, both inorganic and organotin compounds are likely to be found on sludges and solids in contact with water containing these species. The over-all solvent extraction and detection procedures have lowered the amount of tin and organotin that can be determined in aquatic systems. These methods have been applied to a biologically significant area of Strangford Lough in Northern Ireland (Fig.3). I t is apparent that a consistent and sensitive method of monitoring the possible pathways of organotin compounds into aquatic systems can be achieved. References 1. 2. 3. 3. 5. Vickrey. T. M.. and Harrison. G . V . . Anal. Chem., 1981. 53. 1573. Fritzsche, H., Wedscheider, W., and Knapp, G . , Talanta, 1979, 26, 219. Burns. D . T . . Dadgar, D . , and Harriott. M.. Analyst. 1984. 109. 1099. Burns. D. T.. Glockling. F . . and Harriott. M.. Analyst, 1981, 106, 921. Burns, D. T.. Harriott. M., and Glockling, F . . Fresenius Z . And. Chem.. 1987. 327, 7019. Analytical Applications of Spectroscopy Edited by C.S.Creaser, Uniuersity of East Anglia and A.M.C. Davies, Institute of Food Research, Norwich This book provides a ’ State-of-the- Art’ review of the applications of the major spectroscopic techniques and will prove invaluable to researchers involved in this form of analysis, The book provides wide-ranging coverage of recent developments in analytical spectroscopy, and in particular the common themes of chromatography - spectroscopy combinations, Fourier transform methods and data handling techniques. Each section includes a review of key areas of current research, written by spectroscopists who have made major contributions in their respective disciplines, as well as short reports of new developments in these fields. These common themes have played an increasingly important part in recent advances in spectroscopic techniques and emphasise the multidisciplinary approach of present research, 502 pages ISBN 0 85186 383 3 Price $47.50 ($99.00) ~~~~ ~ ~~ To order or for further information, please write to: Royal Society of Chemistry, Distribution Centre, Blackhorse Road, Letchworth, Herts SG6 IHN, UK or telephone (0462) 672555 quoting your credit card details. We now accept Access/Visa/MasterCard /EuroCard. RSC Members are entitled to a discount on most RSC publications and should write to: The Membership Manager, Royal Society of Chemistry, Thomas Graham House, Science Park, Milton Road, Cambridge CB4 4WF, U.K.

ISSN:0144-557X    

DOI:10.1039/AP9892600255

出版商:RSC    

年代:1989

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS, JULY 1989, VOL 26 263 Industrial Applications of IR and Raman Spectroscopy The following are summaries of two of the papers presented at a Meeting of the Molecular Spectroscopy Group held on November 24th, 1988, in Birkbeck College, London. Applications and Limitations of Fourier Transform Raman Spectro- scopy F. J. Bergin Shell Research Ltd., Thornton Research Centre, P.O. Box I , Chester CHI 3SH H. F. Shurvell Department of Chemistry, Queen's University, Kingston, Ontario, Canada K713N6 In the past the application of Raman spectroscopy as an analytical tool has been severely restricted because of problems of laser induced fluorescence. This fluorescence arises either intrinsically from the material itself or from trace impurities present in the sample.The intensity of this fluorescence is often several orders of magnitude stronger than the scattered Raman signal, and thus any useful spectroscopic information is lost. Many different approaches have been tried to circumvent this problem. These include time resolved spectroscopy, photo- bleaching, resonance enhancement, surface enhancement, and the use of far ultraviolet or far red lasers. Another approach that has been demonstrated recently is that of Fourier transform Raman spectroscopy. In this case an Nd - YAG laser, lasing at 1064.1 nm, is used and an FTIR spectrometer, modified to operate in the near infrared, replaces the conventional Raman spectrometer. The rationale for using near infrared excitation is that the laser excitation energy is, in general, too low to excite fluorescence.Unfortu- nately, whilst considerable fluorescence rejection can be obtained, it is not without its cost. For example, the scattered Raman signal is inversely proportional to the fourth power of the wavelength. This leads to a reduction in signal intensity by a factor of 18 on moving from 514.5 nm to 1064.1 nm excitation. Coupled with this, the near-infrared solid-state detectors are orders of magnitude less sensitive than the photomultiplier tubes used in conventional Raman spectroscopy. Despite these restrictions the technique of FT- Raman opens up new possibilities for Raman spectroscopy. This presentation outlined some initial experiments illustrat- ing some of the benefits and restrictions of this new and emerging technique, coupled with some preliminary experiments on FT - Raman microscopy.Experimental The spectrometer used for these experiments was a Perkin- Elmer, Model 1760, Fourier transform near infrared spec- trometer. The excitation source was a cw Nd - YAG laser from Spectron Lasers, operating at typically 1 W at the laser head. Alignment of the sample optics was facilitated by a He - Ne laser running coaxially with the Nd - YAG laser. Rejection of emission from the laser flash lamp system and the laser plasma lines was achieved by using a combination of a twin prism system and a narrow band interference filter. Narrow band interference filters were also used for both the external alignment and internal reference He - Ne lasers. A 10 cm focal length lens focused the Nd - YAG beam to approximately a 1 mm spot at the sample and the scattered radiation was collected in a 180" geometry by using an ellipsoid mirror supplied by Perkin-Elmer.This ellipsoid mirror, designed to match the spectrometer f-number, gathered the scattered radiation from the 1 mm spot and magnified it up to fill the 8 mm Jacquinot stop. Filtering of the Rayleigh scattered light was achieved by placing two dielectric coated filters in the optical path to give an optical density of approximately 8 at 1064.1 nm. Unfortunately, there was a trade-off between adequate Rayleigh rejection and the detection of low fre- quency Raman signals. In this instance the lower limit of detection was of the order of 300cm-1. The higher limit was set by the detector used. In this instance the liquid nitrogen cooled germanium detector gave an upper limit of approximately 3100 cm-1. For the microscopy studies a conventional Raman micro- 0 500 1000 1500 2000 2500 3000 Raman shifticm-' Fig.1. ( a ) . FT - Raman spectrum of anthracene recorded through microscope; 135 mW at sample ; 100 scans. ( b ) , M - Raman spectrum of anthracene recorded using macro-optics; 135 m W at sample; 100 scans264 ANALYTICAL PROCEEDINGS, JULY 1989, VOL 26 scope was used (a modified Nikon Optipot metallurgical microscope). For this work the macro optics were simply replaced by the microscope system. The laser was brought to the sample via a 12.5% beam splitter and focused by a ~ 4 0 glass objective. The size of the focused spot was dependent on the nature of the sample used but on a glass slide it was of the order of 5-10 pm in diameter.Results and Discussion The advantages and limitations of the technique were outlined by using a single-scan spectrum (6-s analysis time) of anthracene. The advantages included a high degree of fluores- cence rejection, speed and simplicity of analysis, and improved data processing facilities. These advantages were tempered by some restrictions, which included reduced sensitivity and limited spectral range. The applications focused on two main areas of analysis, namely fuels, lubricants and allied materials and coloured polymeric materials. Several examples from each category were shown highlighting the effective fluorescence rejection achieved and the complementary nature of the data obtained from infrared and FT - Raman spectra.The main purpose of using near-infrared excitation is to avoid fluorescing electronic energy levels, and indeed, in most instances, this is achieved. But it is far from true to say that FT - Raman is entirely fluorescence free. Several spectra were presented which showed that even under 1064.1 nm excitation considerable fluorescence can be observed; indeed in some instances little or no vibrational information can be extracted from the observed spectra. Fig. l(a) shows the spectrum of anthracene recorded using the microscope system, while Fig. l ( h ) shows a spectrum recorded by use of the macro optics. Each spectrum was recorded using a solid pressed pellet of anthracene with 13SmW at the sample and with a data collection time of 7.2Smin.Although the spectrum in Fig. l(a) is clearly identifiable as anthracene there is a reduction in signal to noise ratio of approximately 6. This reduced signal to noise ratio was, in part, explained by the sampling geometry, i.e., the ellipsoid had a solid angle of collection of 6.28 sterads as compared with 1.51 for the microscope. Although the spot size of the laser on a glass slide was of the order of 5-10 ym the analysis area in this instance was somewhat larger. This fact was further emphas- ised by the difficulty in obtaining any data from single flakes of the material of the order of 20ym in diameter. A more appropriate example for evaluation was shown using a spec- trum of a polyurethane elastomer. The signal to noise ratio of the observed spectrum recorded through the microscope suggested that the current system is not, as yet, sufficiently sensitive for analytical purposes. Conclusions These initial experiments showed that the use of near infrared excitation gives considerable fluorescence rejection, allowing Raman spectra to be recorded from such highly fluorescing materials as fully formulated oils, additives and coloured polymeric materials. It was noted that in some instances even near infrared excitation does not overcome the fluorescence problem. The possibility of recording FT - Raman spectra on a microscopic scale, using a conventional glass optics system, was demonstrated.

ISSN:0144-557X    

DOI:10.1039/AP9892600263

出版商:RSC    

年代:1989

数据来源: RSC

摘要:

264 ANALYTICAL PROCEEDINGS, JULY 1989, VOL 26 Fermentation of Cheese Whey-Monitoring by FT - IR P. Fairbrother, W. 0. George and J. M. Williams Department of Science and Chemical Engineering, Polytechnic of Wales, Pontypridd, Mid Glamorgan CF37 1DL The production of cheese in the world has been steadily rising. Cheese is made by adding rennin to milk to coagulate the curds which are separated off to ripen as cheese. The liquid remaining is cheese whey, which amounts to about 83% of the volume of the milk feedstock. The composition of whey depends on the type of cheese being manufactured but is typically’ about 5% lactose with fat, protein and other materials amounting to 2-3%, with water as the remainder. In previous times whey has either been fed to pigs or disposed of into the environment: it has a high BOD (35000- 40 000 p.p.m.2).With large factory-type cheese plants concern for environmental impact and appreciation of the unique nutritional and functional properties has prompted research into whey modification and utilisation. In 1955, the dairy industry processed 25% of the liquid whey produced, but by 1975, 75% was processed to utilise its nutritional and energy content. The uses included the production of liquid fuel and biogas and the growing and harvesting of yeast,3 and in the production of speciality products including lactic and citric acids, lysine, threonine, fats, xanthan gum, vitamins, enzymes and antibiotics.4 There have also been substantial uses of whey in the food industry.“.“ Alcohol Fermentation Ethanol is formed by yeast cells as a means of regenerating oxidised pyridine nucleotides in the absence of oxygen.The term “industrial fermentation” is applied to any large-scale cultivation of microbes, including those processes which are aerobic.’ Currently, 75% of bioethanol is produced by batch, stirred tank methods. In general, the investment cost of batch methods and control devices is low but the manpower costs are high. The short time of fermentation decreases the risk of contamination but reduces the economic viability. In a semi-continuous process the medium is only partly removed and the residue serves as inoculum for the next run. In both batch and semi-continuous processes the yield of ethanol is low. In a fully continuous process there is continuous addition of nutrient and continuous removal of cells and fermenter medium.The initial change in concentrations is similar to the batch process but a steady state is soon achieved. Yeast Strain Maiorella and Castillos evaluated an industrial batch process for producing ethanol from cheese whey using Candida pseudotropicalis ATCC 8619. The scale of operation was 250001 of whey per day, corresponding to the output of a typical cheese plant. It was estimated that the plant would yield 720 1 d-1 of 190 degree proof ethanol and 40 kg d-1 dry mass of Candida pseudotropicalis yeast. This would reduce the BOD of effluent by 90% from 35 000 p.p.m. to 3500p.p.m. at a net cost of $9.5 per 1000 1 of whey and would add 7.3 US cents per kg to the cost of cheese. This strain was used in the present work although a number of other strains have been found to be effective in particular circumstances.”10 Materials Cheese whey was obtained from Castle Dairies Ltd., Caer- philly; lactose, ethanol, sulphuric acid, sodium hydroxide, ammonium sulphate and ammonium chloride from BDH;ANALYTICAL PROCEEDINGS, JULY 1989, VOL 26 265 Fig.1. solution Photograph of arrangement of FT spectrometer with cell linked to on-line system for circulating fermentation liquid or calibration yeast extract from Difco Laboratories, Detroit, Michigan; and Candida pseudotropicalis ATCC 8619 from American Type Culture Collection, Maryland, USA. The pre-treatment of cheese whey and the preparation of the starter cultures will be described in more detail elsewhere.11 Spectroscopic Methods All samples were measured in a Spectra-Tech multiple internal reflection “Circle Cell,” arranged for continuous flow measurements within the cell compartment of a Digilab FTS 50 Fourier Transform IR Spectrometer, using the QUANT 32 software for quantitative analysis.For recording a water background spectrum and calibration solutions a 500 ml detachable flask was connected to the cell via a circulatory peristaltic pump. In the spectrum of lactose two strong bands occur at 1076 and 1042cm-1, with weaker bands at 1156,1119 and 998cm-1. In ethanol a strong band occurs at 1046cm-1 with a weaker band at 1085 cm-1. The QUANT 32 programme was used to measure the areas between specific intervals of all seven bands. For recording samples during fermentation the flask was replaced by the fermenter vessel.The configuration of the fermenter, calibration vessel, cell and F T spectrometer are shown in Fig. 1. Spectra were scanned in the range 1300-950 cm-1. Sixty-four repeat scans were averaged for calibration samples. The resolution was 8 cm-1 at a noise level of 0.01 using triangular apodisation. In parallel with changes in ethanol and lactose concentra- tion , growth curves for Candida pseudotropicalis were deter- mined from measurements of absorbance at 550nm, using a Bausch and Lomb, Spectronic 501, ultraviolet - visible spec- trometer. “On-Line” Fermentation Analysis A 900-cm3 sample of sterile, partially deproteinised whey (PDW) (pH 4.57) was transferred to the fermenter, which is shown in Fig. 1, and the heater stirrer set to 30 degrees.The whey was inoculated, aseptically, with 10 cm3 of starter culture using a sterile syringe via an inlet port at the top of the fermenter. The stirrer and peristaltic pump were switched on leading to a continuous flow of medium from the fermenter through the flow cell and back to the fermenter. Following inoculation a computer program was initiated which recorded, saved, and plotted spectra every 30min for 24 h (Fig. 2). At the end of the period the stored spectra were analysed. Calibration of Spectra of Cheese Whey by the K Matrix Approach If the absorptivity, a, and the path length, b, are combined into a single constant, K , then The Beer Law expression then takes the form If the absorbance, A l , for a mixture of components of concentrations, c1 , c2, .. . c,, is assumed from Beer’s Law to be K = a b . . . . . . * f (1) A = K c . . . . . . . . (2)266 ~~~~ ~ Fig. 2. Repeat scans of fermentation mixture at 30-min intervals over 24 h between 950 and 1300 cm-1. Note the diminution of lactose bands at 998, 1042, 1076, 1119 and 1156 cm-l and the growth of ethanol bands at 1046 and 1085 cm-I additive for a particular wavenumber value, 1, A1 = klcl + k2~2 + ... + k,c,, . . . . (3) In general, (2) is a matrix equation and in the case of a two-component mixture such as ethanol and lactose the matrix can take a simple form (4) where c1 is the concentration of ethanol and c2 is the concentration of lactose. Absorbance measurements are made at two wavenumber values, Al and A2. If the two bands are not overlapped then: In general, absorption bands overlap and the entries in the K matrix are non-zero.These entries can be computed by over-determination of calibration data by measurement of a larger number of standards and wavenumber values than the minimum needed (two in the present work). The concentration values of the standards and the wavenumber values at which measurements are made are chosen to optimise the results of a particular unknown systern.I2 The K matrix is determined within the QUANT 32 package by a least-squares regression based on seven measured absorbances on each of 13 solutions of known ethanol and lactose composition as the calibration step. The matrix is then used to calculate concentrations of fermentation liquid from measured absorbances as the analytical step.Precision and Accuracy A printout of the calculated values for the 13 standard mixtures is given in Table 1, which shows a root mean square error of 0.1059 and 0.1196 when compared with known values for ethanol and lactose, respectively. This gives an indication of precision of the on-line fermentation results. The accuracy would be dependent on the nature of other components present in the sample but absent from the standards. In principle, subtraction of standard bands from sample bands would show bands from additional components. It follows that using QuAN.r 32, accuracy is effectively limited by the quantitative physical performance of the instrument and some knowledge of the components present in sample and standards. ANALYTICAL PROCEEDINGS, JULY 1989, VOL 26 Results Fermentations were carried out by using 10 and 25cm3 of inocula with and without 1% supplements of yeast extract and ammonium sulphate or chloride.Typical representations of results from a particular run are shown in graphical form in Fig. 3, but may also be printed out in tabular form. In terms of previous considerations it would be possible to pursue greater accuracy, but in terms of needs for the purpose of the present on-line monitoring work the results have reasonable reliability and enable the following conclusions to be drawn. ~~ Table 1. The composition of calibration mixtures and the back calculation of concentration of each mixture as an indication of precision Ethanol concentration, %mlV Lactose concentration, %mlV Actual Measured Error Actual Measured Error 4.1240 4.1590 -0.0350 0.1500 0.1834 -0.0334 3.9650 4.1518 -0.1868 0.2000 0.1362 0.0638 3.3310 3.2026 0.1284 0.7500 0.7406 0.0094 3.1720 3.0111 0.1609 1.0000 1.0204 -0.0204 2.8550 2.9712 -0.1162 1.2000 1.1600 0.0400 2.5380 2.4265 0.1115 2.0000 1.8791 0.1209 2.2200 2.1951 0.0249 2.5000 2.6848 -0.3848 2.0620 2.0286 0.0334 3.0000 3.1210 -0.1210 1.5070 1.4976 0.0094 3.7500 3.7160 0.0340 1.1100 1.1823 -0.0723 4.0000 3.7857 0.2143 0.9520 0.9500 0.0020 4.2500 4.4751 -0.2251 0.6740 0.8287 -0.1547 4.5000 4.3690 0.1310 0.3970 0.2957 0.1013 4.7500 4.7662 -0.0162 RMS error 0.1059 RMS error 0.1 196 Conclusions Firstly, an increase in inoculum size led to an increase in the rate of ethanol production.Secondly, addition of nutrients increased the alcohol production rate, but led to a decrease in lactose utilisation and ethanol production.Thirdly, the growth of Cundidu pseudotropicalis appeared to parallel the produc- tion of alcohol. Fourthly, increased aeration led to a rise in the growth rate of the yeast, which suggests that forced aeration may lead to a decrease in fermentation time. 5 L I +-+- +. p 4+-+-+, $ 1 +'t. 0 5 10 15 20 25 Timeih Fig. 3. The production of ethanol and the utilisation of lactose by Cundida pseudotropiculis using a 25-cm3 inoculum: a. ethanol; + , lactose Hence, quantitative FT - IR has proved to be an effective method for on-line analysis of the alcoholic fermentation of cheese whey. The technique could readily be transferred from a laboratory or pilot plant scale to an industrial scale with real time process control.Future Developments-FT - IR Using an Optical Fibre? The use of a mid-infrared transmitting optical fibre for on-line analysis has recently been reported by Compton et al.13 TheANALYTICAL PROCEEDINGS, JULY 1989, VOL 26 ~ Light Microscopy is one of the oldest techniques at the disposal of the analyst and is unfortunately greatly undervalued and underused in the analytical laboratory. It is, in fact, a conventional economical technique which should not be overlooked and can be of great value in the analysis of foods, pharmaceuticals, metals, plastics, water, I agrochemicals, textiles and much more. 267 In this book the authors draw upon their considerable experience in industry and consulting practice, to provide examples of the many and varied uses of light microscopy in analysis.They describe in detail its capabilities and seek to encourage its wider use in actual practice, reminding analysts of its qualities and applications. They also advocate good practice in its use. 1 Microscopists, analysts and students alike will gain much from the authors’ enthusiasm and as a result may assist in extending the utility of the instrument into the future. possibility of remote sampling by carrying the spectral informa- tion through an optical fibre opens up exciting new possi- bilities, including studies of samples which are not readily placed in the cell compartment of a spectrometer. These include hazardous materials, processes inside reactors, indus- trial furnaces and remote environmental systems.Currently, the transmittance of optical fibres is limited to about 1200cm-1, but it is to be hoped that this will be extended further into the infrared region and make available the wealth of information in the infrared to sensors which were, hitherto, largely limited to single bulk measurements. References 1 . 2. 3. Kosikowski. F. V., “Cheese and Fermented Milk Products,” Edwards Brothers Inc., Ann Arbor, Michigan, 1977, p. 450. Singh. V., Hsu. C. C., and Tzeng, C. H . , Process Biochem., 1983.37, 13. Mann, E. J . , Dairy Ind. Int., 1987, 52, 12. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. Kosaric, N., and Wieczorek, Dev. Food Sci., 1982, 9, 229. Mann. E. J., Dairy Ind. Int., 1988, 52, 6. Kennedy, J . P., Cultured Dairy Prod., 1985, 20, 13.Primrose, S. B., “Modern Biotechnology.” Blackwell Scien- tific Publications, Oxford, 1987, pp. 5141. Maiorella, B. L., and Castillo. F. J., Process Biochem.. 1983, 19, 157. Castillo, F. J., Izaguirre, M. E., Michelena, V., and Moreno, B., Biotechnol. Lett., 1982, 4, 567. lzaguirre, M. E., and Castillo, F. J., Biotechnol. Lett., 1982,4, 257. Fairbrother, P., George, W. O., and Williams, J . M., In preparation. Crocombe, R. A., Olson, M. L., and Hill, S. L., in McClure, G. L., Editor, “Computerised Quantitative Infrared Analysis, ASTM STP 934,” American Society for Testing and Materials, Philadelphia, 1987, pp. 95-130. Compton, D. A. C., Hill, S. L . , Wright. N. A., Druy, M. A . , Piche, J . . Stevenson, A., and Vidrine, D. W . , Appl. Spec- trosc., 1988, 42. 941. An Introduction to Applications of Light Microscopy in Analysis By D. Simpson and W.G. Simpson, Analysis for Industry, Thorpe-Ze-soken Price 229.50 ($63.00) ISBN 0 85186 987 4. Hardcover 215pp information Services To order or for further information, please write to the: Royal Society of Chemistry, Distribution Centre, Blackhorse Road, Letchworth, Herts SG6 lHN, UK or telephone (0462) 672555 quoting your credit card details. We now accept Access/Visa/MasterCard /EuroCard . RSC Members are entitled to a discount on most RSC publications and should write to: Membership Manager, Royal Society of Chemistry, Science Park, Milton Road, Cambridge CB4 4WF, UK.

ISSN:0144-557X    

DOI:10.1039/AP9892600264

出版商:RSC    

年代:1989

数据来源: RSC

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268 ANALYTICAL PROCEEDINGS. JULY 1989, VOL 26 Equipment News Mass Spectrometer Equally suited to high sensitivity, high resolution GC - MS and high relative molecular weight LC - MS measurements, the SX-102 can detect very small traces of drugs, pesticides and pollutants using the SIMS GC - MS technique. It also has wide LC - MS applications using the FRIT inlet system, including the analysis of amino acids, peptides and proteins, genetic research and pharmaceutical and other studies. It features QQHQC ion optics geometry pioneered by Professor Mat- suda at the University of Osaka. The SX-102 has a practical mass range of 3000a.m.u. at 8kV, but compounds greater than 5000a.m.u., such as bovine insulin, can be measured. Specifications include sensitivities such as 2 X 10.7 C pg-1 methyl stearate and resolu- tions of 60 000 and above.Jeol (UK) Ltd., Jeol House, Grove Park, Colindale, London NW9 OJN. RF Generator Designed to complement the benchtop PU7450 inductively coupled plasma spec- trometer, a new type of free-running RF generator operates at 40.68 MHz and offers several advantages over existing 27.12MHz RF generators. The energy produced by the oscillator is more effi- ciently transferred to the plasma as the frequency increases, so that the plasma source is more robust and hence easier to ignite and more tolerant of difficult sample matrices. Moreover the signal to background ratio is improved for a num- ber of elements, with a consequent ben- eficial effect on detection limits. Philips Scientific, York Street, Cam- bridge CB1 2PX.Fourier Transform Infrared Spectrometer The Model 1725-X is a PC-controlled instrument equally suited to analytical or research laboratories. The standard optical system covers the range 7900 to 370cm-* with a resolution of 2cm-1, upgradeable to 0.5 cm-1. Versions are also available to cover the near-infrared or far-infrared regions. Upgrades and accessories include multiple detectors, external beam, GC - IR, TG - I R and IR microscopy. Perkin-Elmer Ltd., Post Office Lane, Beaconsfield, Buckinghamshire HP9 1QA. Software for Infrared Spectroscopy A range of software packages which run on the IBM (TM) PS/2 Series or Epson (TM) computers is announced. Infrared Data Manager (IRDM) is a program for viewing and manipulating infrared spec- tra. Data can be imported and exported using JCAMP-DX and LOTUS (R) 1-2-3 format.Packages are also available to control the makers’ infrared spectro- meters. PC SEARCH is an expert spectral interpretation program. Many commer- cial libraries are available including the entire Sadtler collection. Perkin-Elmer Ltd., Post Office Lane, Beaconsfield, Buckinghamshire HP9 1QA. Software for Diode Array Spectrometry Two new software packages increase the versatility of the makers’ HP 8452A diode array ultraviolet - visible spectropho- tometer and ChemStation. A QUANTITA- TION software package simplifies single component method development and multi-component analysis. The Enzyme Kinetics System automates many of the processes involved in investigating enzyme reactions and reaction rates. Hewlett-Packard Ltd., Miller House, The Ring, Bracknell, Berkshire RG12 1XN.Benchtop Atomic Emission Detector The first totally automated multi-element atomic emission detector for gas chroma- tography, the HP 5921A, is capable of selectively detecting any element (except Connectors for Capillary Gas Chromatography Press-Fit connectors can be used for connecting broken fused silica columns, €or combining columns of varying polar- ities or for combining different sizes of fused silica columns. No screwed joints, ferrules or adhesive are required. Thames Chromatography, 16 Raymead Court, Maidenhead, Berkshire SL6 8TN. Electrochemical Detectors for HPLC The installation is announced of the UK’s first Coulochem electrode array system (CEAS). Combining the separation abil- ity of gradient liquid chromatography, the selectivity and sensitivity of electrochem- ical array detectors and the power of modern computer technology, this instru- ment was installed at the Reckitt and Colman Psychopharmacology Unit in the University of Bristol Medical School, which will be researching into such mental disorders as drug and alcohol addiction, epilepsy, anxiety, depression and schizophrenia. Severn Analytical Ltd., Unit 2B, St.Francis Way, Shefford Industrial Park, Shefford. Bedfordshire SG17 5DZ. Self-Flush Pump Head Available in stainless steel and titanium (and soon in polymer) the head uses the action of the pump to deliver a wash Hewlett-Packard HP 5921 A atomic emission detector helium) in gas-chromatographic effluents. Combining a new atomic-emission source with a flat focal-plane spectrometer con- taining a movable diode array, and con- trolled by the HP ChemStation, the new detector, autosampler and gas chromato- graph provide total automation from ele- ment selection through report generation. Hewlett-Packard S.A., Route du Nant- d’Avril 150, P.O.Box-CH-1217 Meyrin 2, Geneva, Switzerland. solution to the area behind the high pressure seal. The self-flushing pump head (12-0158 for stainless steel, 12-0159 for titanium) is optional on the makers’ 200 Series pumps and the Model 300 pump. It can be retro-fitted on other makers’ pumps, such as Perkin-Elmer’s Series 10, Isco 2300, ESA 5700 and the BAS PM-48. A self-flushing pump head is also available for the makers’ Model 350 pump in stainless steel (12-0303).ANALYTICAL PROCEEDINGS, JULY 1989, VOL 26 269 Scientific Glass Engineering (UK) Ltd., Potters Lane, Kiln Farm, Milton Keynes MKll 3LA.Cartridge Guard Columns for HPLC A cartridge guard column system has been developed. I t is simple to use and introduces no efficiency loss. Easy to remove without the need for spanners, the cartridges are available packed with every commercial packing material. HPLC Technology Ltd., Wellington House, Waterloo St. West, Macclesfield, Cheshire SK 1 1 6PJ. HPLC Column Adaptor Permitting change from one column to another in 15 s, the new design of adaptor connects HPLC columns regardless of male or female fittings. N o tools are needed, there is zero dead volume, the adaptor is proof tested up to 6000 Ib in-?, and it provides a convenient mounting plate for the injector.Thames Chromatography, 16 Raymead Court, Maidenhead, Berkshire SL6 8TN. Post Column Interlock System for HPLC A new post column eluent flow interlock has been designed to protect against equipment damage caused by accidental reverse flow of rcagents. The device (Part 1100-121 1) includes four 120 V recep- tacles, status lights, re-set button, circuit breaker, power cord and a pressure switch connected by a 5-foot cord. Pickering Laboratories, 1951 Colony Street, Suite S, Mountain View, CA 94043, USA. Oxygen Analyser The Model 326 on-line analyser provides reliable monitoring of per cent. oxygen in a wide range of gases and gas mixtures. Measuring ranges from 0-1% to 0-100% are available with an option of up to 10 bar partial pressure of oxygen for hyper- baric applications.Explosion-proof and intrinsically safe versions can be pro- vided, with certain models to CENELEC standards. Teledyne Analytical Instruments, The Harlequin Centre, Southall Lane, South- all, Middlesex UB2 5NH. Combustion Gas Analysers EDT Analytical Ltd. have been appoin- ted exclusive UK distributor for the range of portable combustion gas analysers manufactured by IMR GmbH of West Germany. The range includes measuring systems for any combination of the fol- lowing gases in air down to the p.p.m. level: oxygen, carbon dioxide (by calcula- tion), carbon monoxide, sulphur dioxide, nitrogen oxides and hydrogen sulphide. In addition the following combustion parameters are determinable: air entry and exhaust gas exit temperatures, draught/pressure, lambda, eta and soot.EDT Analytical Ltd., 14 Trading Estate Road, London NWlO 7LU. Thermal Conductivity Analyser The Model 235 on-line thermal conductiv- ity analyser provides accurate monitoring of gases in a variety of applications, for example: hydrogen in petroleum refinery hydrocarbon streams, ammonia syn- thesis, turbine generators and blanketing gases; gas purity monitoring of argon, oxygen, hydrogen, nitrogen, helium and other gases in air liquefaction; monitoring gas proportions for process control of mixtures such as nitrogen - argon, hydrogen - nitrogen, helium - air and oxygen - nitrogen; and other applications where the thermal conductivity of one gas is significantly different from that of the other gases in the mixture.Teledyne Analytical Instruments Ltd., The Harlequin Centre, Southall Lane, Southall, Middlesex UB2 5NH. Dewpoint Calibrator The Series 4000RS dewpoint meter is a compact, self-contained instrument which enables calibrations to be made down to less than 0.5 p.p.m. or -80°C dewpoint. It is capable of accuracies of 0.1-0.2"C dewpoint over a range from -80 "C to full saturation. Michell Instruments Ltd., Unit 9, Nuf- field Close, Nuffield Road, Cambridge CB4 1SS. Sulphur Monitors and Analysers Hobre Instruments (UK) Ltd. have been appointed sole UK agent for the range of total sulphur, specific sulphur and hydrogen sulphide monitors and analys- ers made by Tracor Atlas of Houston. The systems available provide analyses in p.p.b., p.p.m. or percentage ranges.Total sulphur laboratory analysers utilise sample introduction by syringe for gases and liquids, and sample boat for solids. Versions are available for on-line process measurement of hydrogen sulphide and sulphur compounds in gases and liquids, including water effluents, chemicals, crude oils and petrochemicals. Hobre Instruments (UK) Ltd., Pen- tagon House, 52 Castle Street, Trow- bridge, Wiltshire BA14 8AU. pH Meters A range of instruments is announced: the F14, F15 and F16 for bench use and the D14, which is a dual purpose bench/port- able meter. They offer random order auto-calibration, auto-buffer recognition, locked read-out with auto-hold and a limited number of keys for data entry. They are supplied with a complete set of accessories.Data storage facilities are offered as standard on the F14 and D14, whilst the F15 and F16 have a built-in thermal printer. Horiba Instruments Ltd., Harrowden Road, Brackmills, Northampton NN4 OEB. Haemoglobinmeter A compact, portable instrument, micro- processor controlled and easy to use, offers rapid and accurate measurements necessary for anaemia diagnosis and patient management. It provides direct readings in either cyanmethaemoglobin or oxyhaemoglobin, ranging from 1 .O- 20.0 g dl - 1. Biotron Ltd., Church Lane, Bishop Thornton, Harrogate, North Yorkshire HG3 3JP. Plasmid Ion Exchange Column The HRLC MA7 plasmid column pro- vides a rapid alternative for the purifica- tion of plasmid DNA. In less than 1 h the HRLC MA7 column (7.8 x 50 mm) yields 150 vg of biologically active plasmid DNA which is free from detectable RNA and Hohre Instruments sulphur monitor270 ANALYTICAL PROCEEDINGS, JULY 1989, VOL 26 chromosomal DNA.A 1.0 X 10.0cm preparative HRLC MA7 column is avail- able for the purification of milligram amounts of plasmid. Bio-Rad Laboratories Ltd., Caxton Way, Watford Business Park, Watford, Hertfordshire WD18RP. Protein A and Protein G Affinity Columns Two new Luer Tip Quick (LTQ) affinity columns are designed for rapid purifica- tion of antibodies on a small scale. LTQ columns are available with either Protein A or Protein G immobilised on 0.2g HiPAC silica. They have a capacity of 5 mg human IgG and 2 mg mouse IgG. ChromatoChem Inc., 2837 Fort Mis- soula Road, Missoula, MT 59801, USA. Water Purifier The ROstill reverse osmosis water puri- fier can supply up to 401 daily of high purity water. It employs water pressure rather than electricity and so does not have scaling problems.Purite Ltd., Unit E, Bandet Way, Thame Industrial Estate, Thame, Oxfordshire OX9 3SJ. Adsorbent Tubes for PCBs ORB0 60 adsorbent tubes contain highly purified, deactivated Florisil packings for adsorbing airborne PCBs. They effi- ciently release PCBs by solvent desorp- tion. Their low interfering background contaminant levels and desorption effi- ciencies comply with NIOSH Method 5503. Consistently reproduced bed weights maintain performance from tube to tube and lot to lot. Supelchem UK Ltd., Shire Hill, Saf- fron Walden, Essex CBll 3AZ. Solid Phase Extraction Tubes The DrugPak-T solid phase extraction tube provides efficient sample clean-up in conformational urine analyses for THC and its metabolites.Absolute metabolite recoveries are over 85%. Both the sensi- tivity of the proprietary bonded phase and the recoveries it provides lower the probability of false negatives and un- detected THC abuse. Extracted samples can be quantitatively analysed by GC - MS or GC - FID. Supelchem UK Ltd., Shire Hill, Saf- fron Walden, Essex CBll 3AZ. Standards for US Contract Laboratory Programme All of the volatile organic compounds on the US EPA Target Compound List (TCL) are included in a series of five new calibration standards. Highly concen- trated components (2000 pg ml-1 each) make them suitable for purge and trap analyses, multi-point calibrations or in combinations of two or more mixtures.Starting materials are directly traceable to EPA reference materials from the Quality Assurance Materials Bank. fron Walden, Essex CBll 3AZ. Supelchem UK Ltd., Shire Hill, Saf- Software for Surface Analysis With the MAES software package, which runs on IBM PC or PC AT compatible computers and provides a tool for spec- trometric analysis using Auger and ESCA methods, it is possible to perform both qualitative and quantitative analysis in just 2 min. MAES automatically carries out tasks such as peak detection, element nature identification and background removal. Other functions include peak synthesis with a choice of sophisticated Gaussian, Lorentzian or mixed lines shape synthesis. Spectro Systems, Tour du Credit Lyon- nais, 129 rue Servient, F-69003 Lyon, France.Surface Area Analyser The ASAP 2000 surface area and por- osimetry unit combines fast analysis time, complete automation and a high level of analysis versatility in a single analysis port unit. It can use analysis gases other than nitrogen (krypton for example) by virtue of the high, clean vacuum attained. The menu-driven, multi-tasking controller provides real-time, on-screen display of information. Two analysis units can be attached to a single controller. Micromeritics, One Micromeritics Drive, Norcross, GA 30093-1877, USA. Laboratory Reactors IKA reactors are suitable for pharmacies and laboratories which have to produce small samples of salves, pastes and creams. They are designed for hygienic mixing, kneading, dispersing (under vac- uum or inert gas), homogenising, heating or cooling.There are two models: the LR250, with a capacity of 75-250m1, a stirring speed range of 15-125 revolutions min-1 and which uses an S 25 N-10 G-VS high speed dispersing tool, handles tem- peratures up to 150 "C and attains a vacuum down to 30mbar; and the LR1000, which has a vessel capacity of 300-1000 ml, a stirring speed adjustable between 2.5 and 400 revolutions min-1, uses the S 25 KG-18 G high speed dispersing tool, operates up to 150 "C and attains a vacuum of 30 mbar. Sartorius Ltd., Longmead Industrial Estate, Blenheim Road, Epsom, Surrey KT19 9QN. Precision Scales The IB range of scales are suitable for applications such as parts counting, fill- ing, batching, classification, check weigh- ing and formulation.Their weighing ranges offer a capacity up to 31 kg to an accuracy of 0.lg. They comply with the IP65 and NEMA 4 standards and can be used in dirty environments. Sartorius Ltd., 18 Avenue Road, Bel- mont, Surrey SM2 6JD. Elevator Tube Furnace The Model ETF is a vertical tube furnace featuring an operational temperature range of up to 1700"C, which can be reached within 15min from ambient. It incorporates a tubular work area of up to 5in diameter, which can be profiled in accordance with the needs of the process application. A tube diameter in excess of 5 in can also be specified. Lenton Thermal Designs Ltd., 12-14 Fairfield Road, Market Harborough, Leicestershire LE16 9QQ. Chamber Furnaces The LSF Series is a family of six bench mounted chamber furnaces, three having a maximum operating temperature of 1100 "C and the remainder 1200 "C.Each is available in three standard capacities: 3.5, 7.0 and 13.01. A variety of optional control systems is offered, including two- term (P + D) and three-term (PID) temperature controllers, and sophisti- cated, programmable, multi-segment time - temperature controllers. Lenton Thermal Designs Ltd., 12-14 Fairfield Road, Market Harborough, Leicestershire LE16 9QQ. Pump A new line of 1-in air operated diaphragm pumps, which offer 100% purity of pro- duct, an externally serviceable, oil-free air mechanism and a non-stall feature, are fabricated from pure PTFE or poly- propylene with no contaminants or fillers. The solid-block design permits continu- ous operating temperatures of 225 "C with higher temperature capability available, depending upon the chemicals being han- dled.The 1-in pump has variable capaci- ties up to 151 1 min-1 and pressures up to 758 kPa. There are five sizes: +in, 2 in, 1 in, 14 in and 2 in. American Pump, Osmonics Inc., 5951 Clearwater Drive, Minnetonka, Minne- sota 55343, USA. Pumps The 23500 Series Tonkaflo multi-stage centrifugal pumps offer pulse-free opera- tion and deliver 11-68 m3 h-1 with operat- ing pressures to 2584 kPa. Constructed of durable Noryl and corrosion-resistant 316 stainless steel, they are available with seven different impeller sizes. Tonkaflo Pumps, Osmonics Inc., 5951 Clearwater Drive, Minnetonka, Minne- sota 55343, USA. Centrifuges The Howe - Sigma range of centrifuges are silent and maintenance free because of their brushless drive motors. The range of benchtop, floor-standing and refriger- ated models can take both swing out and angle rotors.Each is microprocessor con-ANALYTICAL PROCEEDINGS, JULY 1989. VOL 26 27 1 trolled and displays all centrifugal parameters, offering simple programming of r.p.m., rotor identification, gravita- tional field, rotor radius, bucket, time, time integral, density, temperature, pro- gression of acceleration and deceleration, up to 100 user programmes, 20 linear and quadratic curves of acceleration or deceleration and pre-coding of rotors. V. A. Howe and Co. Ltd., 12-14 St. Ann’s Crescent, London SW18 2LS. Centrifugal Decanter A solid-bowl type decanter is capable of operating continuously for 24h per day and it has an estimated lifespan of over 20 years.It can be used for clarifying liquids, solid phase concentration (extracting liquid from a solution) and for particle separation. In each of these modes it can handle products with a variety of textures, fibrous, amorphous, thixotropic, col- loidal, granulated and crystalline, in con- centrations from 2 to 70%. Features include speed adjustment (giving a maxi- mum centrifugal force of 5000 s), torque control and choice of draining devices for liquid extraction. It also offers both counter and co-current operation. Guinard Centrifugation, 156 boulevard du General-de-Gaulle, F-92380 Garches, France. Leak Detector The HLT 150 portable helium leak detec- tor offers a detection range of from 10 to 4 x 10-9 mbar 1 s-1.It is the first detector of its kind to feature two test ports, allowing the separation of hydrocarbon-free test- ing from work on other vacuum systems. Balzers High-Vacuum Ltd., North- bridge Road, Berkhamsted, Hertford- shire HP4 1EN. Laboratory Disposables The Media range includes different forms of Petri dishes, cuvettes, specimen con- tainers from 7 to 800 ml, round bottomed polystyrene tubes, serological pipettes and pipette tips. They are manufactured at a purpose-built factory which meets the requirements of I S 0 9002/BS 5750. WHM and Partners Ltd., Cathedral House, 5 Beacon Street, Lichfield, Staf- fordshire WS13 7AA. Complexing Agent Powder Neodisher TR-3 is able to remove metal salts when used in the cleaning of labora- tory instruments.It can be added to water of any hardness to remove contrast media, such as for X-rays, or coupled with an alkaline cleaning agent such as Neo- disher A8 for the removal of both metal salts and grease. It complies with all hygiene laws, being safe and non-toxic in normal use. The Scientific Instrument Centre Ltd., Unit 34D, Parham Drive, Boyatt Wood, Eastleigh, Hampshire SO5 4NU. Process Seals Three cartridge mounted high-perfor- mance process seals have been introduced for high-speed, high-pressure application in refineries, chemical, pulp and paper process plants and in water and slurry services. The 133 single seal has withstood pressures of 35 kg cm-2, surface speeds of 4000 ft min-1 and temperatures of 290 “C. The 233 double seal has the same capabili- ties; its double sealing provides added security in sealing hazardous and costly fluids and gases.The 234 double seal is similar in design to the 233 but its extra- heavy-duty parts permit pressures up to 50 kg cm-2 inboard and 35 kg cm-2 out- board. Bulletin 73930 gives details. Chesterton International Inc., P.O. Box 518, Virginia Water, Surrey GU25 4ST. X-ray Fluorescence Software An optional program for calculation of theoretical “alpha” matrix correction coefficients has been added to the makers’ X40 software package for their range of X-ray spectrometers. Alphas can be derived for any type of material, without need to purchase numerous tables or type in large volumes of data. It is also possible to utilise a combination of theoretical and experimental alphas if necessary.Philips Industrial and Electro-acoustic Division, 5600 MD Eindhoven, The Netherlands. Spectrophotometers Models in the new PUS625 series of ultraviolet - visible spectrophotometers feature just five panel keys for simple set-up and control, and an easy-to-read LCD display which presents results in absorbance, % T or concentration. A built-in analogue output provides the option of monitoring all three parameters continuously with time. Available in visible (325-1100 nm) and ultraviolet - visible (195-1100 nm) versions, the new instruments are suitable for both routine and more demanding applications. There is a bidirectional RS 232C interface and any standard RS 232C printer can be attached. A wide range of accessories includes flow action sample throughput (FAST), which allows the processing of large numbers of samples without the need continually to change the sample by first removing the cell from the cell compartment.Philips Scientific, York Street, Cam- bridge CB12PX. Sequential X-ray Spectrometer The PW1480 is a versatile system for applications requiring high performance and flexibility in the analysis of solids, powders and liquids. It offers a wide choice of collimator and crystal options, plus a &directional, eight-position crystal changer to facilitate custom tailor- ing of the instrument for specific applica- tions. Philips Electronic Instruments Co., 85 McKee Drive, Mahwah, NJ 0743, USA. Software for X-ray Spectrometry The X-40 analytical software package is a program used to control Philips X-ray spectrometers.It provides facilities for both quantitative and qualitative opera- tion of spectrometers and features a user interface which supports both command and menu modes. The package reduces calculation time by allowing automatic qualitative and semi-quantitative analysis of several samples with a single command. User supplied standards eliminate the need for special expensive standards. Philips Electronic Instruments Co., 85 McKee Drive, Mahwah, NJ 07430, USA. Diffractometry System for Powder Analysis The PW1800 is a fully integrated diffrac- tometry system for automated qualitative or quantitative powder analysis in research and industrial applications. It incorporates a recently developed goniometer. All diffractometer functions are automatically controlled by a built-in Philips Scientific PU8625 ultraviolet - visible spectropliotometer272 ANALYTICAL PROCEEDINGS, JULY 1989, VOL 26 array of five microprocessors, which respond to commands stored in the memory, entered via a keyboard terminal or received on-line from an external computer source.Philips Electronic Instruments Co., 85 McKee Drive, Mahwah, NJ 07430, USA. X-ray Diffraction Software PC-APD is an analytical software pack- age for the Philips IPD integrated powder diffractometer, MPD1880 multi-purpose diffractometer system and CPD compact powder diffractometer. Developed for the IBM XT/AT/PS2 or compatible com- puters, such as the Philips P3200 series, the package offers a means of system automation for powder diffractometry applications.Philips Electronic Instruments Co., 85 McKee Drive, Mahwah, NJ 07430, USA. Microanalytical and Image Process- ing System The EDAX PV9900 analyser combines energy dispersive X-ray microanalysis with image processing and analysis cap- abilities. Equipped with a precise, digi- tally controlled electron beam scan gener- ator and a comprehensive library of image processing functions, it provides real-time image collection, manipulation and dis- play. The full-function digital scan gener- ator facilitates the collection of X-ray and electron signals and simplifies the charac- terisation of elemental distribution in a sample region. EDAX International Inc., 85 McKee Drive, Mahwah, NJ 07430, USA. X-ray Fluorescence Spectrometer The PV 9551 is an energy dispersive X-ray fluorescence spectrometer system de- signed for fast, simultaneous multi- element analysis of a wide variety of specimen types.EDAX International Inc., 85 McKee Drive, Mawah, NJ 07430, USA. Ultraviolet Spectroscopy System The combination of the Lambda 6 optical bench with a PC provides a system appropriate to a wide variety of ultra- violet applications. The PC provides instrument control, extensive data hand- ling and outstanding storage capability for complete automation of spectral data analysis. Data automatically acquired from the Lambda 6 can be processed using software packages, such as the makers’ PECSS and the mouse driven ultraviolet data managment package. The Lambda 6 system can be linked to a variety of output devices, and with JCAMP output it is possible to export data to many third-party software pro- grams.Perkin-Elmer Ltd., Post Office Lane, Beaconsfield, Buckinghamshire HP9 1QA. Software for Spectrophotometry The MPG software package is now avail- able to manipulate and process data from the makers’ DU range of ultraviolet - visible spectrophotometers and from liquid scintillation and gamma counters. In the peak area (integrative mode) a baseline is automatically established, peaks are identified and peak area is reported. It is possible to change the base line, add and delete peaks and provide graphic and tabular print-outs. The new dissolution 6/12 Soft-Pac software module, also for use with DU spectropho- tometers, provides convenient automatic on-line dissolution analysis from one or two baths. It integrates system operation and control, sample delivery, data acqui- sition and hard-copy reporting.Analy- tical wavelength can be selected for pro- ductive analysis extending up to 166.6 h determined by the time interval and number of baths. By using one or two wavelengths, the Soft-Pac module also allows for automatic background correc- tion of raised or sloping base lines caused, for example, by sample turbidity . Beckman, Progress Road, Sands Indus- trial Estate, High Wycombe, Bucking- hamshire. Gas Chromatograph - Mass Spec- trometer System The Shimadzu GCMS-QP2000 standard system is comprised of the GC-14A gas chromatograph, equipped with a split - splitless sample injector for capillary columns, and a new mass spectrometer linked through an MS - capillary column interface.By using hyperbolic quadru- pole electrodes, a mass range of 10-920 is provided with a resolution of 2 a.m.u. (maximum 1800) and a detection limit of 1 ng of methyl stearate. The standard data processing software provides mass spec- tra, total ion chromatograms, mass frag- mentograms, mass spectrum analysis, chromatogram analysis and background subtraction. Dyson Instrument Ltd., Hetton Lyons Industrial Estate, Hetton, Houghton-le- Spring, Tyne and Wear DH5 ORH. HPLC System Another System Gold configuration has been added to the makers’ range of HPLC systems: the System Gold Prep 60, which is capable of purifying microgram to multi-milligram amounts of biomolecules. The system automates column equilibra- tion, elution and column wash proce- dures.All system parameters, including flow-rate, composition, solvent selection, wavelength, range and external relays, are a part of files addressed through the system controller. Modules are equipped with preparative liquid heads for flow- rates of 0.003-30 ml min-1; double flow mode provides flow-rates up to 60 ml min-1 for isocratic separations. Beckman, Progress Road, Sands Indus- trial Estate, High Wycombe, Bucking- hamshire. Reversed Phase HPLC Column The Hamilton PRP-3 column is designed for the purification and isolation of proteins and polymers, greater than 90% protein recovery being possible. The poly- meric packing can be regenerated at least five times by a simple overnight process. The column allows operation from pH 1 to 13. V. A. Howe and Co. Ltd., 12-14 St.Ann’s Crescent, London SW18 2LS. Pumping System The Suprex Microflow system, now avail- able from Dyson Instruments, features user-friendly software. It has applications in SFC, SFE - MS, LC - MS and micro- bore or capillary liquid chromatography. Dyson Instruments Ltd., Hetton Lyons Industrial Estate, Hetton, Houghton-le- Spring, Tyne and Wear DH5 ORH. Gas Chromatography Column The DB-FFAP column is now available for the GC analysis of C3-CI8 free fatty acids. It features a cross-linked and sur- face bonded, acidified, polyethylene glycol phase. A wide range of organic acids can be analysed, including phenol, cresol and xylenol, along with acidic pharmaceuticals and other acidic com- pounds of interest. Water based samples can be analysed and the column can be operated at its temperature maximum of 250 “C without losing peak symmetry.If contaminated it can be restored by rinsing with organic solvents other than methanol. J and W Scientific, 91 Blue Ravine Road, Foisom, CA 95630, USA. Electrophoresis System A new technique, High Resolution Dynamic Imaging (HRDI), permits the observation of bands during electro-ANALYTICAL PROCEEDINGS, JULY 1989, VOL 26 273 phoretic separations as they move through the sample gel and the recording of the results of any time in the process. It eliminates the cumbersome steps required with gel staining and autoradio- graphy and it lets the user determine when compounds of interest are suffi- ciently separated. Since HRDI is a non- invasive optical technique it can be used to monitor continuously a separation; it is therefore suitable for investigating the process of electrophoresis itself.Molecular Dynamics, 240 Santa Ana Court, Sunnyvale, CA 94086, USA. Ion Exchange Membranes Bio-Rex ion exchange membranes are composed of ion exchange beads en- meshed in polytetrafluoroethylene mem- brane. The latest addition to the range is the Bio-Rex ion exchange membrane with Chelex 100 chelating resin. The Chelex ion exchange membrane consists of styrene divinyl benzene copolymer resin particles with paired immunodiacetate ions, which acts as chelating groups in bonding polyvalent metal ions. The selec- tivity of the resin for divalent over mono- valent metal ions is 5000 to 1, with a particularly strong attraction for transi- tion metals even in high salt concentra- tions.The resin functions as a chelating resin at pH 4 and above; at very low pH it acts as an anion exchanger. Bio-Rad Laboratories Ltd., Caxton Way, Watford Business Park, Watford, Hertfordshire WD1 8RP. Oxygen Analyser The 1184 dual channel oxygen analyser consists of two identical oxygen trans- ducers mounted together in a tempera- ture controlled environment. Applica- tions include calorimetry experiments in human and animal physiology, where small differential oxygen values measured over long periods need to be measured with time invariant high accuracy. Servomex Ltd., Crowborough, Sussex TN6 3DU. pH Electrode The Ross Sure-flow pH electrode is an all-glass electrode designed to give improved reliability in non-aqueous titra- tion.Non-aqueous titration is used for the assay of many organic chemicals and to measure the total acidity and alkalinity of materials such as used lubricating oil. Typical titrants include solutions of per- chloric acid in glacial acetic acid, or potassium hydroxide in methanol. Sam- ples are prepared in glacial acetic acid or other solvents such as toluene and pro- pan-2-01. Orion Research UK, Freshfield House, Lewes Road, East Sussex RH18 SES. pH - Redox Transmitters Two pH - Redox transmitters in similar wall (Model 4535) and panel (Model 4545) mounting cases are announced. Measured value, programming paramet- ers and information such as alarm set- tings, measured temperature and elec- trode check value are indicated in a 4% digit blue filtered vaccum fluorescent display.Ranges are programmable between -2.00 and +16.00 pH, from 0 to k 1000 mV and - 10 to + 110 "C. Kerlt Industrial Measurements Ltd., Howard Road, Eaton Socon, Hunting- don, Cambridgeshire PE19 3EU. Rheometry Instruments The Rheomat 108E is a rechargeable battery operated viscometer capable of executing shear rate ramp programs with the measured data automatically stored in memory, from which they can be output to a printer or to a computer through the integral Centronics and RS 232 interfaces. The Rheomat 115A is a computer con- trolled viscosity measuring unit offering fully automatic measuring and evaluation processes, optimised output and report programs, and extension possibilities for data management. The Covimat 101/105 series instruments are rotational vis- cometers with concentric cyclinder measuring systems to determine the dynamic viscosity of liquids.Designed for process viscosity monitoring and regula- tory applications, the Covimat 101/105 features the multi-speed capability neces- sary to cover a wide viscosity measuring range with high accuracy. Contraves Industrial Products Ltd., Times House, Station Approach, Ruislip, Middlesex HA4 8LH. Automatic Sampler for Particle Size Analysis The MasterTech 51 is an automatic sampler accessory for the SediGraph 5100 particle size analyser. The SediGraph 5100 - MasterTech 51 system will analyse from one to eighteen samples automatic- ally in sequence. Mechanical and ultra- sonic agitation built into the MasterTech 51 will re-disperse the next sample to its original level of dispersion; it then trans- fers the re-dispersed sample to the Sedi- Graph 5100 for analysis and reporting.Micromeritics, One Micromeritics Drive, Norcross, GA 30093-1877, USA. Cordless Pipetting Controller A portable electric controller is re- charged by leaving it plugged into the mains electricity supply overnight. It is fitted with a disposable sterile filter and a one-way safety valve. Filling and delivery are effected by means of two fingertip controls. The controller accepts all sizes of glass and plastic pipettes from 0.1 to 100 ml (neck sizes of 2-8 mm). A manual version is also available. J. Bibby Science Products Ltd., Tilling Drive, Stone, Staffordshire ST15 OSA. Remote Link for Sensors The International Sensor Technology range of solid-state sensors for toxic or combustible gases is now available in a wireless system.The remote link system is completely integrated. The sensor's 4-20 mA signals arrive at the control room for connection to any IST monitor, IBM or compatible system. Acal Auriema Ltd., 442 Bath Road, Slough SL1 6BB. Portable Air Velocity Meter and Printer Sierra Instruments have introduced the Data-Trak portable air velocity monitor and printer. The microprocessor-based Data-Trak remembers a thousand indivi- dual air velocity or temperature readings, displays them digitally and computes their average. The infrared printer provides instantaneous, hard-copy records and has no electrical cords. Also available are a choice of Sierra velocity probes: the Accu-Flo probe for everyday measure- ments and the Steel-Trak probe for indus- trial and high temperature applications.Acal Auriema Ltd., 442 Bath Road, Slough SL16BB. Test Sieve Shaker The Octagon 300 is designed for 300 mm test sieves. A variation of the established 200 model, it offers quiet operation with larger sieves and sample sizes. It features quick-release clamps, which hold the sieves firmly in place without over- tightening, an intermittent timer and amplitude control. It not only holds seven sieves of 300 mm diameter but it also takes 12 full-height or 2.5 half-height sieves of 200 mm diameter. Endecotts Ltd., Lombard Road, London SW19 3BR.274 Panel Instrumentation Specifically designed for power current applications, the S E l l l recording multi- meter is based on a compact flat-bed recorder and offers 48 calibrated current measurement ranges for both a.c.and d.c. values from 0.6 to 1.5 mA fuse protected and 6 A unprotected, and for voltages from 150 mV to 750 V. The SlOO series of panel meters feature interchangeable scales, enabling them to be easily adapted for different applications. The SE560 high speed digital recorder is ideal for measur- ing, storing and evaluating transient and waveform signals, including those impos- sible to detect with conventional measur- ing instruments such as laboratory record- ers. The SE631 plotter generates high resolution colour graphics up to A3 size in only 2 min; its operating noise level is only 55 dB(A). It has a resident memory for colour separations of graphics data, and high resolution and vivid colour make it ideal for colour-graphic applications, par- ticularly those which involve polygram fill.It also has a built-in character font. AEB Metrawatt Ltd., 4 Imperial Square, Cheltenham, Gloucestershire GL50 1QR. Transmission Electron Microscope Based on the advanced microcontroller operational concept, the CM20 200 kV TEM combines ease of use with powerful materials analysis performance. It offers analysis of micro-areas by using high intensity TEM and STEM probes down to a few nanometres, atomic structure analy- sis by direct imaging, selected area dif- fraction and convergent beam diffraction with large convergence and projection angles, and dynamic imaging, making optimum use of electron beam - specimen interactions such as bright field, dark field, secondary and back-scattered elec- tron signals.The column is designed to allow energy dispersive X-ray analysis, electron energy loss spectrometry and a wide range of other specialised tech- niques. Philips Industrial and Electro-acoustic Systems Division, 5600 MD Eindhoven, The Netherlands. Electron Microscope The 525-M scanning electron microscope facilitates inspection over a wide range of parameters from thin layer chemical com- position to critical dimension and can accommodate specimens up to 8-in diameter. It permits simultaneous opera- tion of several detectors in parallel. Philips Electronics Instruments Co., 85 McKee Drive, Mahwah, NJ 0743, USA. SEM/EDS System PHAX-SCAN is a system for quantitative microanalysis and SEM imaging. A func- tionally integrated SEM and EDS system, it has been designed to take advantage of ANALYTICAL PROCEEDINGS, JULY 1989, VOL 26 the analytical capabilities of the Philips Series 500 scanning electron microscope.It provides user friendliness and high operating speed for a wide range of microanalytical applications, including quantitative digital X-ray maps, digital line-scans, particle analyses, etc. Philips Electronic Instruments Co., 85 McKee Drive, NJ 07430, USA. Tablet Dissolution Tester The SOTAX AT 7 tester features auto- matic centring of the test vessels and exact positioning of the stirrers; the water-bath can be emptied and filled in situ. No additional steps are required to fulfil relevant pharmacopoeia1 requirements. Lasers Low-power carbon dioxide lasers using RF excitation are becoming available as compact and self-contained units.The LGK8000 and LGK8100 are for industrial and medical applications, where precise beam definition is a prime requirement. With continuous power outputs of 5 W and 25 W, respectively, both have a beam purity of better than 95% in the EHll mode and a beam diameter of less than 2 mm measured at the exit point of the resonator tube. Low power lasers can be operated with gas from a sealed reservoir; RF excitation extends the life of the resonator tube and increases the over-all operating efficiency of the laser. SOTAX A77 tablet dissolution tester The SOTAX range includes numerous on- and off-line automated or manual systems, which can be tailored to indivi- dual requirements. SOTAX specialise in the flow-through method for testing the in vitro release of numerous forms of medi- caments ( e .g . , slow-release formula- tions), tablet distintegration and supposi- tory melting-point testers. EDT Analy- tical are exclusive UK distributors for SOTAX pharmaceutical formulation test equipment. Combining Milton Roy’s dis- solution software and dual-beam, high speed scanning Spectronic 1201 spectro- photometer, they can now offer an exten- sive range of formulation equipment. EDT Analytical Ltd., 14 Trading Estate Road, London NWlO 7LU. Water Purifier The STILLplus purifier has been intro- duced to upgrade existing purified water. When fed with distilled, de-ionised or reverse osmosis water, it will remove any remaining minerals, organics or bacteria.The water produced is suitable for atomic absorption, tissue culture, HPLC and ion chromatography. Purite Ltd., Bandet Way, Thame Industrial Estate, Thame, Oxfordshire OX9 3SJ. Siemens Ltd., Siemens House, Wind- mill Road, Sunbury on Thames, Mid- dlesex TW16 7HS. Literature A brochure describes the M-Probe family of ESCA (electron spectroscopy for chemical analysis) systems, which offer sensitivities (count rates) for spectra taken at high energy resolution 3-18 times better than those obtained with the mak- ers’ previous X-Probe systems. Surface Science Instruments, 450 National Avenue, Mountain View, CA 94043, USA. A brochure describes the applications of the two detector systems (pulsed amperometric and suppressed conductiv- ity) used with IonPac polymeric column separations.The columns provide the efficiency of reversed phase but offer selectivities better suited to polar and ionic compounds. Applications include gradient elution of carbohydrates, alco- hols, glycols, amines and other com- pounds. Dionex Corporation, P.O. Box 3603, Sunnyvale, CA 94088-3603, USA.ANALYTICAL PROCEEDINGS. JULY 1989. VOL 26 275 Rheodyne Technical Notes 9, “How to Make Tube Connections Between Injec- tors, Columns and Detectors in Liquid Chromatography,” shows the effects of dead volume and how to reduce it. HPLC Technology Ltd., Wellington House, Waterloo Street, Macclesfield, Cheshire S K l l 6PJ. Issue number 33 of SGE Topics covers BPX70, a new very high stability polar capillary column, Polysil Tubing, Model GAV 200 gas sampler, a fishy solution to on-column injector cooling, cutters for plastic and stainless steel, Valco injection valves and office and exhibition news.Scientific and Glass Engineering (UK) Ltd., Potters Lane, Kiln Farm, Milton Keynes MK11 3LA. A wall chart advises which sensing and reference electrode to use for a wide range of titration reagents and gives information on the cables required, together with comments on suitable titra- tion volumes and cleaning possibilities. V. A. Howe and Co. Ltd., 12-14 St. Ann’s Crescent, London SW18 2LS. Three catalogues describe the Monsanto 2000 series of rheometers and Mooney viscometers. The Rheometer MDR 2000 measures the cure characteristics of com- pounded rubber by using a sealed, rotor- less, moving die system. The Rheometer ODR 2000 measures the cure characteris- tics of compounded rubber in accordance with international testing standards.The Mooney viscometer MV 2000 measures the viscosity and processability of raw or compounded polymers in accordance with international testing standards. Monsanto plc, Edison Road, Dorcan, Swindon, Wiltshire SN3 5HN. A brochure describes the Coulter Delsa 440 for determining the electrophoretic mobility and Zeta potential of colloid systems. The Delsa 440 is ideal for deter- mining the stability of any colloid system, from lymphocytes to metal oxides. Coulter Electronics Ltd., Northwell Drive, Luton, Badfordshire LU3 3RH. Issue 9 of “Laboratory Equipment Info” describes a wide range of equipment, including the Camlab Cub washing machine (on which a brochure is also available), centrifuges, pumps, ultrasonic cleaning baths, syringes and many other items.Camlab Ltd., Nuffield Road, Cam- bridge CB4 1TH. The Winter 1988-89 edition of Chemical Design News describes an automated procedure which constructs 3-D models of proteins from their amino-acid sequences using sequence homology or similarity. The software is based on an approach developed at Birkbeck College, London. There are also items on the development of 3-D GKS drivers for the Apple Macin- tosh 11, customising the Chem-X soft- ware, the ORAC sytem for storage, indexing and retrieval of chemical reac- tion data and other innovations. Chemical Design Ltd., Unit 12,7 West Way, Oxford OX2 OJB. The 1989 Rental Catalogue lists over 400 additions this year and includes over 1600 different products from industrial moni- toring equipment to oscilloscopes, ana- lysers, computers and workstations. It also highlights the new Call Free tele- phone number (0800-88-6000). Livingstone Hire, Livingstone House, 2 4 Queens Road, Teddington, Mid- dlesex TW 11 OLB. A chemometrics consulting group has been created to offer expert solutions to complex data analysis problems in chemistry. InfoMetrix Incorporated, Denny Building, 2200 Sixth Avenue, Suite 833, Seattle, Washington 98121, USA. A bulletin, “DB-23/DB-FFAP,” offers information on applications of two new gas chromatography stationary phases. DB-23 is a polar phase of 50% cyan- opropyl polysiloxane designed for the separation of both cis- and trans-isomers of fatty acid methyl esters and positional isomers. DB-FFAP consists of an acidi- fied polyethylene glycol phase, particu- larly useful for analysing C3-CI8 free fatty acids such as acetic and benzoic acid. J. W. Scientific, 91 Blue Ravine Road, Folsom CA 95630. USA. A brochure shows the applications pos- sible with the Techsphere range of HPLC columns. HPLC Technology Ltd., Wellington House, Waterloo Street West, Maccles- field, Cheshire SKll 6PJ. Water metering and liquid analysis are highlighted in the January issue of Kent Review. Several new product develop- ments in the Kent range of water meters are also covered, as are new extended length Z-CS1 and Z-CS2 carbon sensors, a portable version of the P70M micro- processor-based circular chart recorder and additions to the range of P4000-ICS series of panel mounting instruments. ABB Kent plc, Biscot Road, Luton, Bedfordshire LU3 1AL. A brochure details a broad range of industrial hygrometry instrumentation. In addition to providing operational descrip- tions and specifications of capacitive hygrometers, cooled-mirror dewpoint meters and calibration systems, it de- scribes the principles of capacitive and cooled-mirror hygrometry. Michell Instruments Ltd., Unit 9, Nuf- field Close, Nuffield Road, Cambridge CB4 1SS.

ISSN:0144-557X    

DOI:10.1039/AP9892600268

出版商:RSC    

年代:1989

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS, JULY 1989, VOL 26 275 Ronald Belcher Memorial Lectureship In recognition of the late Professor Ronald Belcher’s interest in education, the Council of the Analytical Division has instituted a Belcher Memorial Lecture to be given annually on an analytical topic by a graduate student. The award will be considered by the Honours Committee, acting on behalf of the Council of the AD. Students will be considered to be eligible if they are registered for an academic session in the year of the award. The decision concerning the award will be made in December. The aim of the award is to commemorate Professor Belcher as a teacher, by encouraging students to make a positive contribution to, and take an active part in, the profession of analytical chemistry. The paper, to be written by the student (see rule 2 below), should be in the form required for submission to “The Analyst.” Rules 1. Candidates must currently be regis- tered postgraduate students of a British University or Polytechnic. 2. The merits of a particular candidate may be brought to the notice of the 3. Honours Committee by any super- visor of postgraduate students regis- tered with a British University or Polytechnic who desires to recom- mend the candidate, by letter addressed to the President of the Division. The letter shall be accom- panied by a paper written by the Student. The award shall be made annually in December and shall be based on an over-all assessment of the originality of the work described in the paper and the significance of its contribu-276 ANALYTICAL PROCEEDINGS, JULY 1989, VOL 26 4.tion to analytical chemistry. The winner of the award will be expected to present his or her work at the Research and Development Topics Meeting following the award. The award will take the form of a presentation scroll plus a sum of E150. The sum is to assist the candi- date to attend a national or interna- tional conference. It will be given to the candidate, up to two years after the granting of the award, on presentation of satisfactory evidence of the candidate’s intention to attend such a conference. 5. An award shall not be made if it is considered by the Honours Com- mittee that none of the papers sub- mitted reaches the required stan- dard. 6. The decision of the Council of the Analytical Division shall be final. 7. Any alteration to these Rules shall be subject to the approval of the Council of the Analytical Division. Submissions should be sent to the President, Analytical Division, Royal Society of Chemistry, Burlington House, London, W1V OBN. The closing date is Friday, September 29th, 1989.

ISSN:0144-557X    

DOI:10.1039/AP9892600275

出版商:RSC    

年代:1989

数据来源: RSC