摘要:

Proceedinas ~ - of the Analytical Division ofThe Chemical SocietyCONTENTS197 Summaries of Papers197 Lasers and Their AnalyticalApplications'199 Silver Medal Lectures'208 Affinity Chromatography'211 Equipment News215 Analytical Chemistry in UKUniversities, Polytechnics andColleges: WolverhamptonPolytechnic217 Obituary21 7 Correspondence218 Analytical Division DistinguishedService AwardVolume 16 No 7 Pages 197-21 8 July 197PADSDZ 16(7)197-218(1979)ISSN 0306-1396PROCEEDINGSJ u l y 1979OF THEANALYTICAL DIVISION OF THE CHEMICAL SOCIETYOfficers of the Analytical Divisionof The Chemical SocietyPresidentR. BelcherHon. SecretaryP. G . W. CobbHon. Treasurer Hon. Assistant SecretariesJ. K. Foreman D. I. Coomber, O.B.E.: D. C.M. Squirrel1Secretary Hon. Publicity and Public Relations Officer Editor, ProceedingsDr. A. Townshend. Department of Chemistry,University of Birmingham, Birmingham, B15 2TTMiss P. E. Hutchinson P. C. WestonProceedings is published by The Chemical Society.Editorial: The Director of Publications. The Chemical Society, Burlington House, London, W1 V OBN.Telephone 01 -734 9864. Telex 268001.Subscriptions (non-members): The Chemical Society, Distribution Centre, Blackhorse Road,Letchwonh, Hens., SG6 1 HN.Non-members can only be supplied with Proceedings as part of a combined subscription with The Analystand Analytical Abstracts.0 The Chemical Society 1979CHEMICAL SOCIETY AUTUMN MEETINGANALYTICAL DIVISION SYM PBSIUMonNew Numerical Methods, Optimisation andPattern Recognition in Analytical Chemistrya tThe University of Lancaster18th-20th September, 1979The nvited lecturers are D. Betteridge, T. J. Buggs, I. Calus, D. C. Champeney,L. Kryger, B. A. Moore, W. H. Swann and J. Kittler. The subjects covered willinclude criteria for rejection of data, correlation of data, the optimisation ofresponse in analytical procedures, applications of Fourier methods, a generalreview of pattern recognition and the characterisation of particle size and shape.For further details contact Dr. J. F. Gibson, t h e Chemical Society, BurlingtonHouse, Piccadilly, London, W1 V OBN

ISSN:0306-1396    

DOI:10.1039/AD97916FX024

出版商:RSC    

年代:1979

数据来源: RSC

摘要:

Vol. 16 No. 7 Proceedings July 1979 of the Analytical Division of the Chemical Society Lasers and Their Analytical Applications The following is a summary of one of the papers presented at the Analytical Division Sym- posium held at the Chemical Society Autumn Meeting on September 19th-Z1st, 1978, at the University of Warwick. Summaries of six other papers presented at the meeting appeared in the March (p.97) and May (p. 154) issues of Proceedings. Laser Remote Sensing of Atmospheric Pollutants B. L. Sharp The Macaulay Institute for Soil Research, Craigiebuckler, Aberdeen, AB9 Z Q J A recent study group report published by the Royal Society1 groups the problems of air pollution into three scales of concern. On the global scale the principal problems identified are those related to the emission of carbon dioxide and its potential effect on radiative transfer in the Earth’s atmosphere and thus, possibly, upon the climate, and those that arise from emis- sions of molecules such as the chlorofluorocarbons and dinitrogen oxide, which have a putative effect upon stratospheric ozone concentrations.Regional scale concern is centred on the emissions of sulphur dioxide and nitrogen oxides.These molecules affect the acidity of precipita- tion and are thought to have direct influences on biota, although the mechanisms are not clearly understood (see for example Brough et aL2 and Cowling and Jones3). On the local scale, air pollution problems are more diverse in nature and usually arise from emissions from industrial plants.The Royal Society report noted above emphasises that systematic investigation of air pollu- tion requires that the relevant species be studied both with respect to their spatial distribution and temporal variation. However, most existing analytical procedures employ point sampling, and can only provide spatial information by the establishment of multiple sampling sites. In addition, because it is often necessary to use a long integration time in order to obtain adequate sensitivity, temporal information is limited.These limitations are compounded when it is necessary to make measurements at heights above the land surface or over difficult terrain. The ability of lasers to transmit relatively large radiation fluxes over considerable distances has opened the possibility of extending spectroscopic methods, previously confined to the laboratory, to the direct in situ monitoring of atmospheric pollution.A variety of spectroscopic phenomena can be employed, for example, Raman scattering, fluorescence, long-path absorp- tion and differential absorption Lidar. Raman Scattering Raman scattering has the advantages that only a single line laser is required for excitation and that suitable high-power sources are available.By appropriate selection of the wavelength of the source, the scattered radiation wavelength can be selected to suit the detection system and the Raman shift enables the detection system to discriminate against Rayleigh and Mie scattering of the source beam. Further, as there is no excited state involved in the process, quenching does not affect the intensity of the scattered signal.The disadvantage of Raman scattering is that the sensitivity of the technique is poor, resulting from the low cross-section of the scattering process. Generally, Raman scattering can be considered to be useful only where pollutant concentrations are high, for example in stack monitoring, or for the measurement of major constituents such as water or oxygen.The problem of low cross-section can be partially overcome by employing the resonance Raman effect. It is well established that when the source of excitation is tuned on, or adjacent to, an absorption band, the cross-section for Raman 197198 Proc. Analyt. Div. Chem. SOC. scattering increases by three to five orders of magnitude.However, to exploit fully this advan- tage a tunable laser is required. These devices have a power output that is approximately three orders of magnitude below that of single wavelength lasers and thus most of the potential gain in sensitivity is not realised in practice. In addition, any resulting fluorescence that occurs may overlap the scattered Raman signal and render it undetectable.LASERS AND THEIR ANALYTICAL APPLICATIONS Molecular and Atomic Fluorescence The cross-section for fluorescence from excited electronic molecular states is about 1O1O higher than that for Raman scattering. However, quenching in the atmosphere as a result of the presence of oxygen and nitrogen decreases the effective cross-section by five to six orders of magnitude.An estimate of the attainable sensitivity is that 1 p.p.m. of sulphur dioxide should be detectable at a range of 100 m by averaging data from 100 separate 1-mJ laser shots. Quantifying data from fluorescence signals is difficult as estimates of the beam intensity in the sampling region are required, as well as a detailed knowledge of the quenching rate, in order to calculate the concentration from the fluorescence photon flux.The cross-sections for atomic fluorescence are exceptionally high, of the order of 10-13 cm2, which, allowing for quenching, reduces to 10-l6 em2, a factor of 1013 improvement on Raman cross-sections. Thus, atomic fluorescence should provide a suitable method for determining ambient or enhanced concentrations of free atomic species (for example, mercury).However, for homogeneously distributed pollution the strongly absorbing atoms would cause severe source beam depletion over short ranges (a few hundred metres) and the corresponding fluorescence signal would be greatly self-absorbed on its return to the detector. Thus, the calculation of concentration is rendered difficult by having to work with a non-linear growth curve and, once again, detailed estimates of the quenching rate are required. Bowman et aL4 have used atomic fluorescence in order to obtain measurements of the sodium atom concentra- tion in the 80-100 km altitude range.The laser transmitted a few millijoules of radiant energy and a 1-m diameter receiving telescope was used to collect the fluoresced photons. This measurement represents ideal conditions for employment of the atomic-fluorescence technique, because the path between the atomic cloud and the observer is largely free from absorbing species and quenching in the sample volume is minimal.Long-path Absorption Spectrometry The simplest scheme for atmospheric monitoring with lasers is to take advantage of the high degree of collimation of the beam and perform a long-path absorption measurement.To over- come the difficulty of locating the transmitter and detector remote from each other a retro- reflector is usually employed, which, for a range of angles of incidence, will return the beam back along the incident direction with a small lateral displacement. The long-path absorption method is particularly useful in the infrared region where tunable sources are generally of low power and detectors are less efficient than those used for visible and ultraviolet spectrometry.Such systems have been employed for the determination of a range of molecular species such as SO,, NO,, NH,, N20 and C2Hq.5 Improvements in the sensitivity of infrared detection by up to four orders of magnitude can be achieved with use of the heterodyne signal recovery technique.6 This is the optical analogue of the normal radio reception method in which the incoming radiofrequency signal is mixed with that from a local oscillator to produce a difference or intermediate frequency, which is then amplified and demodulated to recover the information.Although the method has advant- ages it has not been widely used for optical detection because it requires two lasers of stable frequency, one to act as the transmitter and one as the local oscillator.Mixing is accomplished by allowing the two optical waves to impinge on a specially fabricated photodiode made from copper-doped germanium or mercury cadmium telluride. Recent improvements in laser tech- nology should result in heterodyne spectrometry being more widely used in practical field instruments.Differential Absorption Lidar The advent of semiconductor technology has reduced electronic switching times to the sub- nanosecond region. This reduction, in conjunction with high-speed photoelectric detectors, makes it possible to measure optical events which are separated by only a few nanoseconds.July, 1979 SILVER MEDAL LECTURES 199 During such short time spans light travels only a few metres and thus it is possible to use reflected or backscattered light in order to determine the range of distant objects.The term Lidar is an acronym for Light Detection and Ranging, derived from the more common term Radar. Differential absorption Lidar, therefore, is essentially long-path absorption spectro- metry employing backscattering from the atmosphere in place of a retro-reflector.Measure- ment entails sequentially transmitting into the atmosphere a laser beam tuned alternately to an absorption band of the pollutant molecule and then to an adjacent non-absorbing region of the spectrum. Mie scattering by aerosols and atmospheric particulates returns portions of the beams back towards the transmitter where they are received by a collecting telescope.By measuring the time-lapse between the transmitted and received photons, and from a knowledge of the differential absorption cross-section (the difference between the absolute absorption cross-sections at the measurement wavelengths), the concentration and range distribution of the pollutant can be measured.By appropriate selection of the absorption transition, inter- ference from other background absorptions can be minimised. A measurement would normally involve firing several hundred laser shots and signal-averaging the backscattered information to provide acceptable signal to noise ratios. Currently a number of systems are under development in the UK and the first industrial applications should appear during the coming decade.Performance estimates indicate that it should be possible to detect down to about 10 p.p.b. (parts per lo9) of, for example, sulphur dioxide up to a range of 5 km with approximately 1 km range resolution. This is sufficient for the measurement of ambient concentrations in both rural and urban environments, although improvements would be necessary before the technique could be used to detect pollution in truly remote areas, such as over the oceans or polar regions.I t is perhaps appropriate to end this brief review of laser methods for monitoring atmos- pheric pollution by looking to the future. All of the currently available laser techniques are expensive in comparison with the traditional chemical methods and there is still much work to be done in improving the accuracy and precision of the results obtained.However, it is possible, using laser techniques, to obtain information about the temporal and spatial distribu- tion of atmospheric components that it is impossible to obtain by any other means. Thus, depending on the need, the expense may well be justified.The massive advances that have occurred in electronics and data processing have rendered this aspect of the technology rela- tively straightforward and inexpensive. The development of laser-based equipment into routine instruments, capable of being used by technical staff, depends on further improvements in the performance and reliability of laser sources. It is this aspect which currently limits laser remote sensing of the atmosphere to use as a research tool only. References 1 . 2. 3. 4. 5 . 6. “Pollution in the Atmosphere, A Study Group Report,” The Royal Society, London, 1978. Brough, A., Parry, M. A., and Whittingham, C. P., Chemy I n d . , 1978, 21, 51. Cowling, D. W., and Jones, L. H. P., Soil Sci., 1970, 110, 346. Bowman, M. R., Gibson, A. J., and Sandford, M. C. W., Nature, Lond. 1969, 221, 456. Hinkley, E. D., Ku, R. T., and Kelley, P. L., in Hinkley, E. D., Editor, “Laser Monitoring of the Menzies, R. T., in Hinkley, E. D., Editor, “Laser Monitoring of the Atmosphere,” Springer-Verlag, Atmosphere,” Springer-Verlag, Berlin, 1976, p. 237. Berlin, 1976, p. 297.

ISSN:0306-1396    

DOI:10.1039/AD9791600197

出版商:RSC    

年代:1979

数据来源: RSC

摘要:

July, 1979 SILVER MEDAL LECTURES 199 Silver Medal Lectures The following are the Silver Medal lectures delivered by Drs. C. W. Fuller and J. N. Miller, the fifth and sixth SAC Silver Medallists, at a Meeting of the Division held on December 13th, 1978, in London. Interference Effects in Industrial Inorganic Analytical Chemistry C. W. Fuller Tioxide International Limited, Central Laboratories, Stockton-on-Tees, Cleveland, TS18 2NQ Analytical chemistry is without doubt the most important branch of chemistry in industry as it is of significance in the production of almost every commodity produced today.It is therefore200 SILVER MEDAL LECTURES Proc. Analyt. Div. Chem. SOC. not surprising that the number of analytical chemists working in industry outnumbers any other single group of chemists.The aim of this paper is to illustrate the diversity of interests with which many industrial analytical chemists are concerned by using examples from the author’s laboratory. The paper is entitled “Interference Effects in Industrial Inorganic Analytical Chemistry’’ for two reasons. First, it frequently seems that for every new analysis required there are a number of reasons (or interferences) why the analysis is not straightforward.Second, the comments refer to inorganic analytical chemistry, as this is the area in which the author has worked for some years. The paper is divided into sections representing some of these “interferences” against which industrial analytical development has to proceed. Published Literature The first step in investigating a new analytical determination is to turn to the published literature to find out what, if any, information is already available, then, having found the information, to assess how useful it may be.A factor that one often considers in assessing a published analytical procedure is the calibra- tion graph. However, authors can mislead the unwary reader by misrepresenting their data. For example, an author may illustrate the advantages of his work by carefully selecting a concentration range for calibration purposes that produces a linear graph and then comparing it with another set of results, using a different concentration range, which produced a non- linear calibration graph.The method of standard additions can often be used incorrectly by authors to show the apparent absence of interference effects in an anaIytica1 method.Even though parallel lines are obtained using internal and external calibration graphs it is not certain that interference effects are absent. This may be the result of, for example, the occurrence of an uncorrected background signal, an effect that is normally (now) well appreciated.A more serious problem, and one that is not always appreciated, can occur when the analyst does not consider fully the chemistry involved in a determination. The determinations of mercury and of arsenic, selenium and tellurium using vapour generation techniques coupled with atomic-absorption spectrometry illustrate this point. In both instances the sensitivities of the methods are dependent on the chemical form in which the elements are present in the samples.Therefore, if one uses the method of standard additions, one will always obtain the same sample signals but the slope of the calibration graphs, and hence the concentrations of these elements determined, will depend on the chemical form in which the additions are made. The problems arise when the analyst developing the method fails to appreciate the difficulties and therefore does not avoid the problem when he formulates his analytical procedure.Instrumentation Frequently an industrial analytical chemist is called upon to develop an analytical method for a specific task on a production plant or in the associated control laboratories. One often finds, for various reasons, that commercial analytical instruments are either not available or not suitable for this type of environment.By using good design principles, building one’s own dedicated equipment can provide a more suitable piece of apparatus for the application. A few examples will illustrate the type of equipment which can be constructed. ( a ) In many process industries accurate pH measurement is of considerable importance in ensuring a high and reproducible quality for a Company’s products.Over many years it has been found that commercially available equipment is not robust enough for use on our pro- duction plants ; as a result pH meters have been designed and built to operate specifically under these difficult conditions. (b) The largest expansion in analytical chemistry over the past few years has been in the area of environmental analysis. One specific problem has been the determination of those ele- ments forming volatile hydrides by use of atomic-absorption spectrometry, e.g., arsenic, antimony, selenium and tellurium.Published papers on this work used a hydrogen diffusion flame, a flame-heated silica tube or an electrically heated, wire-wound silica tube as the atom- iser.Although the basic technique was felt to be adequate, none of these systems was completely suitable for routine analytical work.July, 1979 SILVER MEDAL LECTURES 201 An atomiser was designed which consisted of a silica tube housed in a small, electrically heated furnace.l This furnace operated from a variable transformer, in order to enable tem- peratures up to 1100 "C to be obtained.The equipment proved to work well and has since been refined to produce a compact, easy to use, sensitive instrument. (c) Process control laboratories often have specific, repetitive determinations by titration to perform. In the titanium dioxide pigment industry the determination of titanium in final and intermediate products is of great importance. In order to minimise labour involvement an automatic titrator has been designed and built to carry out this determination.(d) Another quality control test carried out in our laboratories is the determination of organic coating levels applied to a pigment. Some pigments have only a single organic coating while other pigments have two organic coatings applied. For single organic coatings a simple carbon determination is adequate for control purposes.However, this is not applicable to the determination of the levels of two organic additions and for these determinations a pyrolysis - gas - liquid chromatographic instrument was built that enabled the rapid determination of both components. Theory of Analytical Techniques Until recent years it has been difficult to overcome unexpected problems, with some analytical techniques, without carrying out a considerable amount of experimental work, because only a poor understanding of the theory of the technique was available.An attempt at illustrating the usefulness of the theory of analytical techniques was made in a series of papers describing the kinetics for the formation of atoms in an electrothermal a t ~ m i s e r .~ - ~ The aim of this work was to develop a relatively simple theoretical model of the atomisation processes, which could then be used to describe various analytically important parameters. To ensure that the theory did not become too complicated and therefore unacceptable to the great majority of analytical chemists two criteria were imposed.The first was that the theory was developed for atomisers operating under isothermal conditions, and the second was that com- mercial graphite furnaces achieved isothermal conditions for the greater part of the atomisa- tion process. The following equation was obtained to describe the rate of change in the number of atoms in an atomiser: __ = k,M(O)exp(-klt)-k2M .. .. .. .. .. dM dt where M is the number of atoms in the gas phase a t time t, M(0) is the amount of element introduced into the cell initially, k, is a first-order rate constant for the formation of atoms and k , is a first-order rate constant for the removal of atoms. This equation can be integrated to give equation ( 2 ) , which describes the number of atoms present in the gas phase at any time t.x M(0) [exp ( - k,t) - exp ( - k2t)] Absorbance ( M ) = p x ___ kl k2--k, where 9 relates the amount of material vaporised to the measured absorbance; it is tempera- ture dependent and is related to the dissociation of metal compounds to form free metal atoms. From these two equations several important factors could be studied and their behaviour predicted. 3-6 Calibration by peak height OY integration measurement.Equation (2) can be differentiated in order to obtain a peak absorbance signal and integrated to obtain the integrated signal. The ratios of these two functions can be compared to obtain the conditions where the measurement of the integrated signal is advantageous compared with peak height measurement. Stopped gas jlow. Graphite furnaces are routinely operated under conditions of stopped gas flow during the atomisation stage, in order to obtain increased sensitivity for many elements.The maximum signal enhancement that can be obtained is given by the ratio of M(0) to the normal peak height signal [i.e., the differential of equation (2)]. Matrix control. It is possible to predict whether the determination of element A in the202 SILVER MEDAL LECTURES Proc.Analyt. Div. Chem. SOC. presence of matrix element B is feasible and to define the optimum analytical conditions for the determination. Interference studies. From equation (2) it is possible to show how the measured absorbance signal changes with variations in the values of k,, k, and @. These theoretical changes can be compared with observed results.Knowing that k, refers to the atomisation process, that k , refers to the removal of atoms from the atomiser and that @ refers to the ratio of atomic to non-atomic species produced during the atomisation process, then predictions can be made regarding the causes of changes in the atomisation process itself. Reaction mechanisms. As with all kinetic measurements, it is possible to postulate reaction mechanisms that are consistent with the data obtained.Applications A major problem encountered in industrial analytical chemistry is the complexity of many analytical procedures appearing in the published literature. In an industrial analytical labora- tory one is always looking for the simplest, quickest and cheapest solution to a problem, while retaining the desired level of accuracy and precision for the determination.Ways in which analytical problems can be significantly simplified are illustrated by the following examples. (a) The determination, by spark-source mass spectrography, of trace elements that have isotope mass numbers close to those of the major matrix elements presents difficulties. These arise from a high degree of fogging, which occurs on the photographic plate in the vicinity of the major element mass numbers, causing a high background signal for which it is difficult to compensate.One way in which this high background signal can be reduced greatly is to fit a small shield to the photographic plate holder.’The shield is positioned on the holder such that secondary ions coming from the surface of the photographic plate strike the shield and therefore do not return to the photographic plate to give the characteristic fogging effect.( b ) When a large number of samples are to be analysed by atomic-absorption spectrometry using the method of standard additions a considerable time is involved in the preparation of the solutions. However, use of a branched capillary tube in place of the standard capillary tube on the spectrometer obviates the need to prepare these solutions.* The analyst instead has only to aspirate the sample solution through one of the two capillary tubes while, in turn, aspirating water and then normal standard solutions through the second capillary tube.The result is that the two solutions mix before they enter the spectrometer’s spray chamber, effectively pro- ducing solutions with standard additions.The calculation of concentrations is made in the normal way, with interference effects corrected for. (c) An additional problem with the use of the standard additions procedure in atomic- absorption spectrometry is the time involved in plotting graphs or calculating results for each determination.The normal standard additions procedure consists of aspirating a blank solution and zeroing the spectrometer readout, followed by aspirating the sample and sample plus addition solutions in turn. The graph of addition against absorbance is then plotted and the unknown concentration in the sample determined from the negative intercept on the con- centration axis.If, however, the analyst has access to a modern spectrometer with a digital readout facility, this procedure can be greatly simplified. The spectrometer readout should, in this instance, be zeroed while aspirating the sample solution. The spectrometer readout should also be set to correspond to the magnitude of the standard additions when aspirating these solutions, using the concentration and curve correction facilities available.Now, when the blank solution is aspirated a negative readout will be obtained on the spectrometer, correspond- ing to the concentration of the element being determined in the sample s o l ~ t i o n . ~ (d) The determination of trace elements in refractory oxides by means of atomic-absorption spectrometry presents two major difficulties: (i), the problem of dissolving the samples; and (ii), the problem of keeping the blank levels low while overcoming problem (i), by using high volumes of acids or by using fusion techniques.These problems were largely overcome by developing a slurry technique for sample prepara- tion in place of the established solution procedures. This approach was used initially for the analysis of titanium dioxide pigments.lO The method was particularly appropriate as these pigments are readily dispersed in aqueous solvents to form stable suspensions.They also have aJuly, 1979 SILVER MEDAL LECTURES 203 particle size of less than 1 pm, which enables them to be analysed directly either by flame atomic-absorption spectrometry, using the discrete sample injection technique with aliquots of 100 pl, or by electrothermal atomisation.The potential of the slurry technique was further improved by adding thixotropic reagents to the suspension media. This enables samples which themselves are not readily dispersed, e.g., ground mineral samples, to be held homogeneously in suspension and thereby allow representa- tive sampling.ll Assessment of Analytical Methods Perhaps the most difficult problem that most analytical chemists encounter is critically to assess the originality, significance and competence of their own work.While this assessment undoubtedly involves a considerable amount of self-criticism, it is an essential part of any work. It is particularly important where research results are to be published because it is often very difficult for other workers, unfamiliar with the work being described, to make these judge- ments without repeating much of the work for themselves.1 . 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. References Broughton, J . R. S., and Fuller, C. W., Proc. Analyt. Div. Chem. Soc., 1977, 14, 112. Fuller, C. W., Analyst, 1974, 99, 739. Fuller, C. W., Analyst, 1975, 100, 229.Fuller, C. W., Proc. Analyt. Div. Chem. SOC., 1976, 13, 273. Fuller, C. W., Analyst, 1976, 101, 798. Fuller, C. W., “Electrothermal Atomization for Atomic Absorption Spectrometry,” Analytical Fuller, C. W., and Whitehead, J., Analyst, 1971, 96, 779. Fuller, C. W., Atom. Absorption Newsl., 1976, 15, 73. Fuller, C. W., Atom. Absorption Newsl., 1972, 11, 65. Fuller, C. W., Analyst, 1976, 101, 961.Fuller, C. W., and Thompson, I., Analyst, 1977, 102, 141. Sciences Monographs, No. 4, The Chemical Society, London, 1977. Recent Advances in Molecular Luminescence Analysis J. N. Miller Department of Chemistry, Loughborough University, Loughborough, Leicestershire, LE 11 3TU The application of fluorescence and phosphorescence to the problems of analytical chemistry began just over 20 years ago with the production of the first commercially available spectro- fluorimetersl and the publication of a crucial paper on phosphorimetry.2 The subsequent development of these methods has been steady rather than dramatic, but a uniquely large number of luminescence methods of analysis are now available (Table I).In practice, they are used almost exclusively in analytical biochemistry, in particular in clinical chemistry, toxicology, food analysis, pharmaceutical analysis and the detection and determination of pollutants.Analyses in these fields present a number of formidable problems, especially (i), the immensely complex sample matrices, e.g., blood and animal tissues, (ii), the small samples, often containing only trace concentrations of analyte, and (iii), the labile nature of the mole- cules under study.Suitable analytical methods must thus be very sensitive (i.e., with ng ml-l TABLE I MOLECULAR LUMINESCENCE ASSAYS 1. 2 . 3. 4. 5 . 6. 7. 8. 9. Direct assays based on the intrinsic F,* P* or RTP* of the sample. Direct assays based on the F (or P?) of labelled or modified samples. Luminescence detection of thin-layer chromatographic and electrophoretic separations (F, P, RTP) .Luminescence detection of HPLC and gas - liquid chromatographic separations (usually F). Chemiluminescence and bioluminescence assays. Fluorimetric enzyme assays (P also 1). Fluorescence immunoassays (FIA ?-several approaches). Fluorescence microscopy. Automation of many assays, e.g., the AutoAnalyzer, centrifugal analysers, flow-injection analysis (FIA ? ? ) .* F = fluorescence, P = phosphorescence, RTP = room- temperature phosphorescence.204 SILVER MEDAL LECTURES PYOC. Analyt. Div. Chern. SOC. or pg ml-l detection limits), and highly selective. The extreme sensitivity of luminescence analysis is well known, and the incorporation of components such as pulsed light sources, photon counters and holographic gratings into luminescence spectrometers is providing con- tinuing improvements ; further improvements can be expected, for example, when laser sources become more widely used.Great sensitivity may, however, be of little value in the absence of adequate selectivity; the analysis of serum levels of the /%blocking drug propanolol provides a recently cited example of the selectivity problems often en~ountered.~ It is thus not sur- prising that many recent advances in luminescence spectroscopy have been directed towards obtaining improved selectivity.These advances can be conveniently classified under three major headings (Table 11). In the present paper I shall survey some of these developments, emphasising in particular those involving optical and electronic modifications of luminescence spectrometers, combinations of thin-layer chromatography and phosphorimetry, and fluores- cence immunoassays. TABLE I1 INCREASED SELECTIVITY IN LUMINESCENCE SPECTROSCOPY A.Optical and electronic modifications of conventional procedures- 1. Derivative spectroscopy. 2. Synchronous-scanning spectroscopy. 3. Use of polarising films.B. Combinations of luminescence spectroscopy and separation techniques- 1. HPLC with fluorimetric detection. 2. TLC - fluorimetry. 3. TLC - phosphorimetry (room temperature or 77 K). C . Combinations of jluorimetry with speci$c biochemical interactions- 1. 2. Fluorescence immunoassays. Enzymatic analysis with fluorimetric detection. Derivative Spectroscopy, Synchronous Scanning and Polarising Films Derivative techniques have been used in conjunction with several spectroscopic methods for many years, but have only recently been applied to luminescence spectro~copy.~~~ The spectra, which show dI/dh, d21/dh2, etc., plotted against h (where I is intensity and h is the wavelength), can be obtained optically (using wavelength modulation, for example) or by electronic processing of the zero-order ( I against A) spectrum.The latter approach, although not without its disadvantages, is much the more convenient and can readily be used to obtain second, third and higher derivative spectra. The signal to noise ratio degrades, however, at each successive differentiation. Differentiation is found to reduce spectral band widths and enhance minor spectral features, thus improving the selectivity of multi-component spectra.Although mostly used in the analysis of hydrocarbon mixtures, in which most of the solutes exhibit well-defined vibrational fine structure, derivative spectroscopy can also be used to resolve broad-band spectra. A recent publication by the present author6 described its applica- tion to the problem of resolving the tyrosine and tryptophan components of protein fluores- cence spectra.It involves the simul- taneous scanning of the excitation and the fluorescence monochromators of a fluorimeter, while maintaining a fixed wavelength difference (Ah) between them. The resulting spectra are much simpler than conventional excitation and emission spectra and have narrower band widths.The method has the further advantage that discrete peaks caused by Rayleigh scattering do not occur, although Raman signals are still dete~table.~ Again, the method has largely been applied to the analysis of hydrocarbon mixtures; at a particular Ah value different hydrocarbons may yield synchronous fluorescence maxima at different wavelengths, and may thus be readily resolved.The reduction of spectral band width is also obtained when broad, featureless spectra are studied. In addition, a further analytical approach is available, vix., using different Ah values in order to isolate the components of a mixture. Table I11 shows the application of this method to the resolution of tyrosine and tryptophan fluorescence. At small Ah values the synchronous fluorescence of a tyrosine - tryptophan mixture is characteristic of tyrosine, whereas at large Ah values spectra similar to that of tryptophan are seen.Synchronous fluorescence spectroscopy was introduced by Ll0yd.~98July, 19’19 SILVER MEDAL LECTURES 206 TABLE I11 RESOLUTION OF TYROSINE AND TRYPTOPHAN FLUORESCENCE BY SYNCHRONOUS SCANNING 7 A/nm 10 20 30 40 50 60 70 80 90 100 h / n m 305 3 14 324 333 343 352 362 371 381 391 Tyr* 7 - +SX/nm 13 14 14 15 15 14 15 14 17 - Trp* h / n m 316 324 333 342 350 359 367 376 384 393 @X/nm - 20 19 20 21 22 22 23 22 Tyr + Trp (equal absorption a t 280 nm) ks/nm 305 315 324 337 350 360 37 1 378 389 395 7 @h/nm 13 15 21 25 24 22 22 23 22 22 * Tyr = tyrosine, Trp = tryptophan.The inclusion of polarising films in the light beam of the fluorimeter is a further method of improving selectivity. In addition to their applications in obtaining polarised luminescence spectra, such films can be used to reduce substantially the scattered light signals in the instrument.1° This leads not only to the removal of interfering Rayleigh and Raman scattered light peaks, but also to a general improvement in signal to background ratios, and hence to improved limits of detection.11 Table IV (adapted from reference 11) demonstrates this effect, which was achieved in this example by the use of a single, horizontally orientated polariser in the excitation beam.It is especially noteworthy that the limit of detection for warfarin in deproteinised blood plasma, using the polariser, is superior to that for pure warfarin in aqueous solution in the absence of a polariser.TABLE IV EFFECT OF POLARISERS ON THE LIMITS OF DETECTION OF LOW RELATIVE MOLECULAR MASS SOLUTES Solute Limits of detection/pg ml-l No polariser Polariser* r A 7 Quinine sulphate 90 5 Warfarin in plasma 6 200 280 Riboflavin 150 5 Warfarin 1500 150 * Horizontally orientated polariser in the excitation beam.Band width 32 nm throughout. It should also be noted that combinations of these three approaches can be valuable. For example, the synchronous fluorescence data in Table I11 were obtained by using a polariser in order to reduce the background scattered light, and derivative synchronous spectra have also been studied.12J3 More sophisticated approaches to increased selectivity include the use of contour spectra,l* which have recently been shown to be closely related to synchronous spectra.l 5 Combinations of Luminescence Spectroscopy and Chromatography In very many fluorimetric determinations, additional selectivity is provided by the use of a chromatographic method. This field is perhaps the most rapidly growing aspect of lumines- cence analysis, involving, in particular, thin-layer chromatography - fluorimetry and high- performance liquid chromatography (HPLC) with fluorimetric detection.In thin-layer chromatography - fluorimetry (reviewed in references 16 and 17) the impetus has come from the development of suitable fluorigenic reagents and the introduction of precise and accurate fluorescence densitometers. Additional recent advances include the development of reversed- phase and high-performance thin-layer chromatographic media.The latter, which facilitate the rapid chromatography of minute samples, can be successfully combined with both fluori-206 SILVER MEDAL LECTURES Proc. Analyt. Div. Chem. SOC. metry18 and phosphorimetry (see below). Fluorimetric detectors for HPLC are used in con- junction with both pre- and post-column derivatisation procedures, and confer an extra- ordinary sensitivity on this rapidly growing m e t h ~ d .~ ~ . ~ ~ The facility for making rapid scans of the fluorescence spectra of the separated fractions is of value in identification, and optical multi-channel analysers21 will be especially useful in this application. The Loughborough research group has been interested for some years in the analytical applications of pho~phorimetry.~~-~~ A thin-layer phosphorimeter has been d e ~ i g n e d ~ ~ , ~ and applied to a number of analytical problems, including determinations of sub-nanogram amounts of 6-mercaptopurine and related compounds6 and phenothia~ines.~~ This instrument, which is designed as an accessory for a spectrofluorimeter, can be used either at 77 K or at room temperature. The development of analytical methods based on the room temperature phosphorescence (RTP) of solutes adsorbed on to chromatographic surfaces has recently accelerated28; this is hardly surprising as the use of liquid nitrogen as a coolant constitutes the most serious obstacle to the widespread use of conventional phosphorimetry.The use of RTP to detect materials separated by high-performance liquid chromatography has also been suggested.29 A further advantage of detecting phosphorescence at a solid surface is that, compared with conventional sampling procedures, improved precision is obtained.26 Fluorescence Immunoassays Analyses combining the sensitivity of fluorimetry with the specificity provided by a bio- chemical reaction are well established.In particular, fluorimetric enzyme assays are in common US~.~O Some of these assays rely on the native fluorescence of compounds normally participating in enzyme-catalysed reactions, especially the co-f actors NADH and NADPH. Others utilise fluorigenic substrates, such as those including the umbelliferyl group. More recently, there has been a rapid growth of interest in fluorescence immunoassays, in which the specificity is provided by the reaction between an antibody and the corresponding antigen or hapten.It seems likely that many analyses currently performed using radioimmunoassays or enzyme immunoassays might be satisfactorily carried out using one or more of the fluores- cence immunoassays listed in Table V.Of the assays listed there, the heterogeneous assays (i-e., assays exactly analogous to radioimmunoassays, which of necessity include a separation step) seem unlikely to be widely applied. Solid-phase assays, on the other hand, are already commercially available, although apparently the only kits so far marketed are for the assay of macromolecular antigens (see, for examples, references 31 and 32).Of the remaining methods, fluorescence protection33 and chemiluminescence assays34 have thus far been little used, though a good deal of development work is certainly in progress. Most attention has focused on the remaining techniques listed in Table V. These techniques all utilise a change in the fluores- cence properties of the labelled molecule, which occurs when it binds to an appropriate anti- body.The assays are thus homogeneous, that is, they do not include a separation step and are thus more easily automated. This advantage, along with the low cost, stability and safety of the fluorescent labels, is the main merit of fluorescence immunoassays. TABLE V FLUORESCENCE IMMUNOASSAY METHODS 1. Heterogeneous FIA.2 . Solid-phase IAs. 3. Fluorescence enhancement IA. 4. Fluorescence quenching IA. 5. Fluorescence polarisation IA. 6. Energy-transfer IAs. 7. Fluorescence protection IA. 8. Fluorescence probe IAs. 9. Chemiluminescence and bioluminescence IAs. The phenomenon of energy transfer is of great value in the development of immunoassays. This eff ect35 involves a non-radiative transfer of energy from one excited fluorescent molecule or group to the ground state of a neighbouring group.Amongst the necessary conditions are that the two groups should be very close together (less than approximately 5 nm) and that the fluorescence spectrum of the donor should overlap the excitation spectrum of the acceptor. Ullman et aZ.36 showed that fluorescein and rhodamine provided a suitable pair of fluorescent labels, and their approach has been used to develop a number of assay^^'-^^; in my laboratory this method is used in the determination of albumin, an assay that can be automated by using flow-injection principle^.^^ Other donor - acceptor label pairs are also under active study.41July, 19 79 SILVER MEDAL LECTURES 207 A different approach to fluorescence immunoassay involves measurements of changes in fluorescence intensity which occur when labelled antigens bind to antibodies. Smith42 developed an immunoassay for thyroxine (T4), based on the quenching effect exerted on fluorescein by the iodine atoms in T4.In the presence of anti-T4 antibodies, this effect is diminished, so that the fluorescein-T4 fluorescence is enhanced.Addition of sample T4 displaces the labelled T4 from the antibody and reverses the effect. We have developed a similar assay using the more convenient flu~rescamine~~ (Fluram, Roche Diagnostics Ltd.) as a label. Contrary to our earlier report,6 however, the mechanisms of the fluorescamine- and fluorescein-based assays are not the same. The quantum yield of fluorescamine-labelled T4 is not significantly lower than the quantum yields of fluorescamine derivatives of other amino acids.Reiterer et al.44 likewise found that the fluorescamine derivatives of both T4 and T3 (triiodothyronine) are not quenched by a heavy-atom effect. It is thus likely that the fluores- cence enhancement observed when fluorescamine-T4 binds to antibodies reflects a change in the polarity of the environment of the fluorophore; this effect can be correlated with the en- hanced fluorescence shown by fluorescamine derivatives in certain organic solvents.45 It might be expected that such an effect would be encountered with many fluorescamine-labelled antigens, and might thus form the basis of a generally applicable fluorescence enhancement assay.Other types of immunoassay which might have general application include fluorescence quenching methods4’ and fluorescence polarisation immunoassays.The principle of this last assay, the increase in fluorescence polarisation when a low relative molecular mass fluorescent species is bound to a high relative molecular mass antibody, has been established for some time,48 and assays for, for example, insulin49 and gentamkin50 have been developed.However, attempts to develop such an assay for T4 failed as the increase in polarisation that occurred was too small to provide an analysis over a useful range of concentrations. Current work in this laboratory suggests that this is indeed the case.46 Future Developments In addition to further advances in the fields outlined above, the next few years will almost certainly see several other important developments in the field of luminescence analysis.Chief amongst these may be the application of microprocessors to data handling problems. It will become much easier to correct luminescence spectra for instrumental characteristics, which will in turn facilitate inter-laboratory comparisons of spectral data and encourage the wider use of the various types of fluorimetric and phosphorimetric analysis.Alternative methods of presenting spectra, e g . , contour spectra, will become easier, and optical multi-channel analy- sers will be of value in studying unstable species and fractions derived from chromatographic separations. Lasers will become more common as excitation sources; they are not without problems (e.g., possible photodecomposition of the sample), but their principal disadvantage, the cost and complexity of producing lasers with suitable ultraviolet excitation wavelengths, is now being overcome.There is thus little doubt that the sensitivity, as well as the selectivity, of luminescence spectroscopy will continue to improve and that this group of methods will continue to play a major role in analytical chemistry.I am deeply grateful for the support and encouragement given to the work of my research group by Professors R. F. Phillips and K. W. Bentley, successively heads of the Department of Chemistry, Loughborough University, and to many collaborators in this research, in particular, Professors J. W. Bridges and D. T. Burns, Drs.L. A. Gifford, T. K. Hwang, L. A. King, D. L. Phillipps and B. F. Rocks, Messrs. G. Handley, C. S. Lim, E. U. Akusoba and H. N. Sturley and Misses A. Al-Mosawi and J. I. Braithwaite. I also acknowledge generous support from the Medical Research Council and the Department of Health and Social Security. References 1 . 2. 3. 4. 5 . 6. Bowman, R. L., Caulfield, P. -4., and Udenfriend, S., Science, N .Y . , 1955, 122, 32. Kiers, R. J., Britt, R. D., and Wentworth, W. E., Analyt. Chem., 1957, 29, 202. Kraml, M., and Robinson, W. T., Clin. Chem., 1978, 24, 169. Green, G. L., and O’Haver, T. C., Analyt. Chem., 1974, 46, 2191. O’Haver, T. C., in Wehry, E. L., Editor, “Modern Fluorescence Spectroscopy,” Plenum Press, New Handley, G., Miller, J . N., and Bridges, J .W., Proc. Analyt. Div. Chem. Soc., 1979, 16, 26. York, 1976.208 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23 24 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. AFFINITY CHROMATOGRAPHY Proc. Analyt. Div. Chem. SOC. Lloyd, J . B. F., Nature Phys. Sci., 1971, 231, 64. Lloyd, J . B. F., J . Forens.Sci. Soc., 1971, 11, 83. Lloyd, J. B. F., Analyst, 1977, 102, 782. Duggan, D. E., Bowman, R. L., Brodie, B. K., and Udenfriend, S., Archs Biochem. Biophys., 1957, 68, Lim, C. S., Miller, J. N., and Bridges, J. W., Analytica Chim. Acta, 1978, 100, 235. O’Brien, I . P., MSc Dissertation, Loughborough University, 1977. Eastwood, D., Fortier, S. H., and Hendrick, M. S., I n t . Lab., 1978, 51.Rho, J. H., and Stuart, J. L., Analyt. Chem., 1978, 50, 620. Weiner, E. R., Analyt. Chem., 1978, 50, 1583. Pollak, V., and Boulton, A. A., J . Chromat., 1972, 72, 231. Lawrence, J . F., and Frei, R. W., J . Chromat., 1974, 98, 253. Seiler, N., and Knodgen, B., J . Chromat., 1977, 131, 109. Slavin, W., Rhys Williams, A. T. R., and Adams, R. F., J . Chromat., 1977, 111, 222. Wheals, B.B., Vaughan, C. G., and Whitehouse, M. J., J . Chromat., 1975, 106, 109. Johnson, D. W., Callis, J . B., and Christian, G. D., Analyt. Chem., 1977, 49, 747A. Gifford, L. A., Hayes, W. P., King, L. A., Miller, J. N., Burns, D. T., and Bridges, H. W., Analyt. Bridges, J . W., Gifford, L. A., Hayes, W. P., Miller, J . N., and Burns, D. T., Analyt. Chem., 1974, 46, Gifford, L.A,, Miller, J . N., Phillipps, D. L., Burns, D. T., and Bridges, J . W., Analyt. Chem., 1975, Gifford, L. A., Miller, J. N., Burns, D. T., and Bridges, J . W., J . Chromat., 1975, 103, 15. Miller, J. N., Phillipps, D. L., Burns, U. T., and Bridges, J. W., Analyt. Chem., 1978, 50, 613. Al-Mosawi, A., Miller, J. N., Phillipps, D. L., and Bridges, J . W., in preparation. Vo Dinh, T., and Winefordner, J. D., Appl. Spectrosc. Rev., 1977, 13, 261. Vo Dinh, T., Walden, G. L., and Wincfordner, J. D., Analyt. Chem., 1977, 49, 1126. Roth, M., Meth. Biochem. Anal., 1969, 17, 189. Harte, R., Clin. Chem., 1978, 24, 1033. Burgett, M. W., Fairfield, S. J., and Monthony, J . F., Clinica Chim. Acta, 1977, 78, 277. Ullman, E. F. U.S. Pat. 3,998,943, 1976. Pratt, J . J., Wolding, M. G., and Villerius, L., J . Immunol. Meth., 1978, 21, 179. Forster, T., Ann. Phys., 1948, 2, 55. Ullman, E. F., Schwarzberg, M., and Rubenstein, K. E., J . Biol. Chem., 1976, 251, 4172. Rodgers, R., Schwarzberg, M., Khanna, P. L., Chang, C.-H., and Ullman, E. F., Clin. Chem., 1978, Eimstand, W. M., Schwarzberg, M., Rodgers, R., Khanna, P. L., Chang, C.-H., and Ullman, E. F., Lim, C. S., Miller, J . N., and Bridges, J . W., Clinica Chim. Acta, submitted for publication. Braithwaite, J . I., and Miller, J . N., Analytica Chim. Acta, in the press. Lim, C. S., Miller, J . N., and Bridges, J . W., in preparation. Smith, D. S., FEBS Lett., 1977, 77, 25. Udenfriend, S., Stein, S., Bohlen, P., Dourman, W., Leingruber, W., and Weigele, M., Science, N.Y., Reiterer, F., Nachtmann, F., Knapp, G., and Spitzy, H., iWikvochim. Acta, 1978, 1, 115. Froehlich, P. M., and Cunningham, T. D., Analytica Chim. Acta, 1976, 84, 427. Handley, G., Lim, C. S., Miller, J . N., and Bridges, J. W., in preparation. Shaw, E. J., Watson, R. A. A., Landon, J., and Smith, D. S., J . Clin. Path., 1977, 30, 526. Kierszenbaum, F., Dandliker, J., and Dandliker, W. B., Immunochemistry, 1969, 6, 125. Spencer, R. D., Toledo, F. B., Williams, B. T., and Yoss, N. L., Clin. Chem., 1973, 19, 838. Watson, R. A. A,, Landon, J., Shaw, E. J., and Smith, D. S., Clinica Chim. Acta, 1976, 73, 51. 1. Chem., 1974, 46, 94. 1010. 47, 1699. 24, 1033. Clin. Chem., 1978, 24, 1015. 1972, 178, 871.

ISSN:0306-1396    

DOI:10.1039/AD9791600199

出版商:RSC    

年代:1979

数据来源: RSC

摘要:

208 AFFINITY CHROMATOGRAPHY Proc. Analyt. Div. Chem. SOC. Affinity Chromatography The following is a summary of one of the papers presented at a Meeting of the Analytical Division held on February 7th, 1979, at the Scientific Societies Lecture Theatre, London. A summary of one of the poster presentations given at the meeting was published in the June issue oE Proceedings (p. 182). Alternatives in t h e Design of Affinity Matrices P.D. G. Dean Biochemistry Department, The UYziversity, Liverpool, L69 3BX Ten years ago, the term affinity chromatography was associated with a radical change in the biochemist’s approach to protein purificati0n.l Prior to this time the only plentiful papers onJuly, 1979 AFFINITY CHROMATOGRAPHY 209 the subject came from immunoadsorption studies.Since then the range of immobilised species has expanded very rapidly, mainly because of the discovery of a suitable support material and a simple activation procedure. The last ten years have not produced many reports of com- parisons of either of these factors and it seems appropriate to review the state of the art in these areas. Apart from these factors, immobilised ligands have developed into a highly complex and very widespread subject .Group-specific ligands have emerged as a highly diverse area ; lectin, nucleotide, hydrophobic, amphiphilic and triazine dye ligands are all examples. The desorption of materials from affinity matrices has also been a matter of continued interest. Matrix Supports and Activation Procedures A widely used combination of support and activation procedure has been agarose and cyanogen bromide.However, very few comparisons with alternatives have been r e p ~ r t e d . ~ - ~ Kohn and Wilchek5 recently described a method for comparing the efficiencies of cyanogen bromide activations of polymers and have demonstrated significant differences between Sephadex and cellulose on the one hand and agarose on the other. These authors concluded that agarose-immobilised amines are largely derived from cyanates, whereas iminocarbonates were more likely to be the active intermediates with Sephadex and cellulose.Cross-linking is probably more likely to occur with the latter matrices than with agarose when these polymers are activated by cyanogen bromide. These considerations have lead to the examination of triazine-based ligands, originally as a means of comparing different matrices with each other, and more recently as an alternative to cyanogen bromide.6 We have examined 2 and 4% agaroses (both cross-linked and untreated gels) ; from studies with both immobilised Cibacron Blue F 3GA and Procion Red HE 3B, we conclude that these ligands behave with comparable efficiency throughout the range of agaroses We have used the Sephadex gel series with similar ligands to extend the concepts of affinity gel filtration (cyanogen bromide activation causes extensive bead damage with SephadexJg which has limited such studies to low ligand concentrations).In several instances Procion Red HE 3B - Sephadexes have been used as alternatives to the agarose-based dye in protein purification.' ,lo We have preferred to use frontal analy~isl1-l~ to examine affinity matrices and conclude from such studies that polyacrylamide, polyacrylamide - agarose copolymers (Ultrogels) and cellulose are unsuitable as supports for triazine-based dyes.Spacers A number of recent studies comparing cyanogen bromide and triazine- (cyanuric chloride) based ligands show that the latter can be superior to cyanogen bromide in several ways : (i), the linkage to the polymer is essentially neutral6; (ii), the linkage is more stable; (iii), the reactivity of the triazine can be adjusted simply and to a considerable degree6,14; and (iv), the ligand can be pre-assembled and activated prior to attachment of the assembly to the support.One recent clarification of the role of spacers has been demonstrated using triazine- immobilised spacers to which oxamic acid has been attached.6 This ligand will bind lactate dehydrogenase in the presence of NAD(H) and was thought to be a rare example of un- complicated affinity chromatography.15 However, Wood and his colleagues6 have shown that hydrophobic spacers are necessary for the NAD (H)-dependent adsorption of the enzyme when cyanogen bromide activation is replaced by triazine coupling.In many nucleotide affinity systems, hydrophobic spacers are likely to continue to be widely used. A valuable synergistic combination of biospecific and hydrophobic elements seems best able to explain the mechanism of these affinity column^.^ Choice of Ligand The development of the concept of group-specific ligands has continued over the last 2 years ; examples of almost every conceivable class of immobilised nucleotide have been reported.A novel demonstration of the use of group-specific supports in the purification of dihydrofolate reductase from L. casei involves chromatography of crude extracts on NADP - agarose, the fractions containing enzyme being re-chromatographed in a subsequent step on the same column following reduction of the NADP to NADPH (using dithionite).The second chromatographic stage produces virtually homogeneous enzyme.ll~210 AFFINITY CHROMATOGRAPHY Proc. AnaZyt. Div. Chem. SOC. The disadvantages of nucleotides as ligands in group-specific affinity chromatography include cost, difficulty of preparation of defined chemical species, instability, sensitivity to bacterial and enzymic degradation and poor capacity.This last has caused us to review triazine-based dyes as alternative^.^ An excellent example of an application of these dyes to protein purification is in the isolation of albumin. A single passage of human serum through a Cibacron Blue - agarose column produces 95-98% pure albumin (by eluting with thiocyanate).The column has a capacity of 2040 mg of albumin per ml (column bed volume). It is inter- esting to note that this phenomenon is species-specific; thus, rat albumin behaves in a similar fashion. However, rabbit, bovine and sheep albumins do not bind effectively to immobilised Cibacron Blue. It has been observed that many NAD-dependent dehydrogenases bind to the column.On the other hand, several NADP-dependent enzymes are more selectively ad- sorbed on to immobilised Procion Red HE 3B. Thus, purifications of dihydrofolate reductase13 from L. casei and 6-phosphogluconate dehydrogenase from B. stearothermophilztsll and A cer psezcdopZatan~s~~ can be achieved by using tandem chromatographic steps on red and blue columns.It should also be mentioned that the above dye columns have considerable potential as negative adsorbents. Thus, the purification of plasma protein spl is greatly facilitated by the removal of albumin using Cibacron Blue - agarose.17 The success of such columns reflects a parallel series of applications of the hydrophobic ligands described by Shaltiel18 and others.A comparison of these two types of ligand indicates that important hydrophobic as well as ionic interactions contribute to the mechanism of protein binding to dye columns. Optimisation Procedures for Affinity Chromatography Of these, temperature has received recent attention. The effects of varying both the temperature of adsorption and desorption have been studied for nucleotide columns using mesophiliclg and thermophilic20 enzymes.The response of these columns to increasing temperatures was found to be quite different ; thermophilic enzymes bound more tightly with increasing temperature whereas mesophilic enzyme binding was weakened under these conditions. On the other hand, the same experiments carried out with triazine dye columns containing immobilised Cibacron Blue F 3GA and Procion Red HE 3B show that increasing column temperatures results in in- creased concentrations of salt being required to elute both thermophilic (I?.stearothermophilus) and mesophilic (yeast) 6-phosphogluconate dehydr~genases.~ I t is concluded that these results indicate the relative importance of the hydrophobic contribution to the binding of these enzymes to triazine-dye columns.Further, this contribution seems to be more important in triazine-dye chromatography than in nucleotide chromatography. Many different parameters can be considered when operating affinity separations. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. References Cuatrecasas, P., Wilchek, M., and Anfinsen, C. B., Proc. Natn.Acad. Sci. U.S.A., 1968, 61, 636. Cuatrecasas, P., J . Biol. Chem., 1970, 245, 3059. Angal, S., and Dean, P. D. G., Biochem. J . , 1977, 167, 301. Dean, P. D. G., and Watson, D. H., J . Chromat., in the press. Kohn, J., and Wilchek, M., Biochem. Biophys. Res. Commun., 1978, 84, 7. Lang, T., Suckling, C. J., and Wood, H. C. S., J . Chem. SOC. Perkin Trans., 1977, 2189. Qadri, F., and Dean, P.D. G., in preparation. Lowe, C. K., and Dean, P. D. G., F E B S Lett., 1971, 18, 31. Doley, S., Dean, I?. D. G., Dietz, G., Harvey, M. J . , and Neame, P. J., in Epton, R., Editor, “Ad- vances in the Chromatographic Separation of Macromolecules,” Ellis Horwood, Chichester, 1976, p. 179. Baird, J. K., Sherwood, R. F., Carr, R. J. G., and Atkinson, A., FEBS Lett., 1976, 70, 61.Dean, P. D. G., and Watson, D. H., in Hofmann-Ostenhoff, O., Breitenbach, M., Koller, F., Kraft, D., and Scheiner, O., Editors, “Affinity Chromatography,” Pergamon Press, Oxford, 1978, p. 25. Dunn, B. M., and Chaiken, I. M., Proc. Natn. Acad. Sci. U.S.A., 1974, 71, 2382. Watson, D. H., Harvey, M. J., and Dean, P. D. G., Biochem. J., 1978, 173, 591. Smolin, E. M., and Rapaport, L., “s-Triazines and Derivatives,” lnterscience, New York, 1950. Barry, S., and O’Carra, P., Biochem. J . , 1973, 135, 595. Atkinson, A., and Dean, P. D. G., unpublished observations. Angal, S., and Dean, P. D. G., FEBS Lett., 1978, 96, 346. Shaltiel, S., in Hofmann-Ostenhoff, O., Breitenbach, M., Koller, F., Kraft, D., and Scheiner, O., Editors, “Affinity Chromatography,” Pergamon Press, Oxford, 1978, p. 141.July, I979 EQUIPMENT NEWS 21 1 19. 20. Harvey, M. J., Lowe, C. R., and Dean, P. D. G., Eur. J . Riochem., 1974, 41, 353. Comer, M. J., Craven, D. B., Harvey, M. J., Atkinson, A., and Dean, P. D. G., Eur. J . Biochem., 1975, 55, 201.

ISSN:0306-1396    

DOI:10.1039/AD9791600208

出版商:RSC    

年代:1979

数据来源: RSC

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July, I979 EQUIPMENT NEWS 21 1 Equipment News Circulator The C-500 Model circulator incorporates vari- able control of the heater power up to a maxi- mum of 3 kW and three fully variable pre-set controls. The temperature range is from -20°C (with flow cooling) to 80°C with a stability of h0.02 "C a t 40 "C. It can be used on large- or small-bore circuits and incorporates a powerful pump. Two cut-out devices protect against overheating and a.gainst low liquid level. Techne (Cambridge) Ltd., Duxford, Cam- bridge, CB2 4PZ.Illuminated Stirrer The IMS-1 assists in the problem of distinguish- ing end-points when carrying out single or multi-stage titrations. The solution is stirred a t a pre-set constant speed, which is fully variable up to 1400 rev min-l, and the top plate illuminates the solution in the vessel to give maximum sensitivity and visibility. The IMS-1 can be used as a high capacity magnetic stirrer for numerous applications other than titrimetric work.Techne (Cambridge) Ltd., Duxford, Cam- bridge, CB2 4PZ. Alternating Current Air Stirrer The ACA-3 heatless stirrer uses low pressure, alternating current air, generated by a special pulsator which requires only 8 W and is connected to the stirrer head by triple-bore silicone rubber tubing.The stirrer is entirely pneumatic and is both explosion proof and heatless. The stirrer head is autoclavable and requires no lubrication. Techne (Cambridge) Ltd., Duxford, Cam- bridge, CB2 4PZ. Microprocessor - based Titration System The Metrohm E636 titroprocessor offers fully automatic operation in chemical titrations with full calculator facilities.Sensitivity, speed, reaction kinetics or any other normal para- meters involved in titration procedures can be programmed into the unit. Full titrations or titrations to a pre-set end-point can be per- formed. The unit can be made to stop after a pre-selected number of end-points have been found, or a t a given mV, pH or ml value. Results are printed out in millilitres to 3 decimal places, together with the mV or pH value a t each end-point and the mV or pH value a t the start of the titration.The burette accepts complete plug-in assem- blies of 1-, 5-, lo-, 20- or 50-ml capacity. All parts in contact with the titrant are made of glass or Teflon, and the burette tap is of a micro-column, flat disc, self-lubricating Teflon design.The integral reservoir is of 1-1 capacity. Roth Scientific Ltd., Alpha House, Alexandra Road, Farnborough, Hampshire. Automatic Beer Analyser SCABA, an automatic beer analyser, measures the alcohol concentration and density of beer samples, then computes, displays and prints original extract, alcohol concentration, apparent and real extract and apparent and real attenu- ation.The sample carrier will accommodate 30 beer samples. An air stream is drawn over the thermo- statically maintained sample and the alcohol in the vapour phase is burned catalytically, the heat generated being measured electrically. In the densitometer the sample passes into a glass resonance cell where the resonance frequency changes in accordance with the density.L. H. Engineering Co. Ltd., Bells Hill, Stoke Pogcs, Buckinghamshire, SL2 4EG. Electronic Sensor An electronic sensor is used for detecting when the filter of portable fume cabinets has reached saturation point. The sensor can also indicate if the wrong filter is being used for that particular gas or chemical. Bigneat Limited, 64 Solent Road, Havant, Hampshire, PO9 1JH.Autoclave Sterilizers The Conclave range of autoclaves, made in stainless steel, incorporate an integral thermal lock to prevent accidental door-opening a t temperatures above 80 "C. Ten models are available with round, square or rectangular chambers in either front or top loading or212 EQUIPMENT NEWS Proc. Analyt. Div. Chcm. SOC. double ended formats.The range also incor- porates a steam exhaust exit from the pressure vessel to enable the required temperature to be set rather than converting from pressure. Cabburn Sterilizers I,td., 9 Towerfield Road, Shoeburyness, Essex. Melting-point Apparatus The apparatus allows direct observation of the specimen under test, using a 3 mm square Platfilm platinum resistance thermometer element as a precisely controlled heater platen, which can be mounted on the stage of a standard microscope.Less than 1 min is required to reach the maximum temperature of 300 O C , with the cooling rate of the same order. Specimens are placed in pure aluminium, disposable dishes, 2.3 mm in diameter by 0.5mm deep, placed on the platen. The melting head is connected to a separate control unit with digital indication of temperature of 0.1 "C accuracy.The heating rate is set by an adjustable control knob, and a hold button enables the observer to "freeze" the reading at the instant the melting-point is reached. A more sophisticated version has a means of pre-setting the temperature and selecting the heating rates to international pharmacopoeia requirements.Rosemount Engineering Co. Ltd., Durban Road, Bognor Regis, Sussex, PO22 9QX. Digital Thermometers The 3501 series of bench and panel mounted digital thermometers can operate in ambient temperatures of -10 to +50 "C with a temperature coefficient of 0.02% "C-l. The Model 3501 is calibrated in "C with a range from -50 to +lo00 "C and a resolution of 0.5 "C. The Model 3502 has a similar range and resolution but is calibrated in O F .Comark Electronics Ltd., Brookside Avenue, Rustington, West Sussex, BN16 3LF. Thermostats The Colora range of constant temperature control instruments is now available through UK agents. Included are five basic types of thermostats with temperature ranges up to a 150 "C maximum. Baird & Tatlock, P.O. Box 1, Romford, Essex, RM1 IHA.Incinerator The Bactiburner incinerator incorporates two independently controlled burners from one gas source. One burner is angled in order to permit easy loop introduction to the flame, which is shielded by a glass tube to prevent spatter. The upright burner is useful for, for example, tube flaming. Models are avail- able for natural gas or butane - propane. A. Gallenkamp & Co.Ltd., P.O. Box 290, Technic0 House, Christopher Street, London, EC2P 2ER. Balance A new model in the Grambuster range, the 1 lTDS, weighs to laboratory standards and is designed for continuous operation even under the harshest conditions. It employs powerful magnetic damping to speed up the weighing process, making the new model capable of rapid catchweight weighing.The inclusion of a 1000-g tare offers the alternative of gross or net weights. Oertling Ltd., Orpington, Kent, BR5 2HA. Bottle Top Dispenser The Fortuna Optifix range of bottle top dispensers now have a PTFE piston giving trouble free dispensing of all media, including concentrated mineral acids and metal alkali solutions. Five models are available covering volumes from 0-100m1, and a full range of adaptors enables almost any size of container to be used.Anderman & Company Ltd., Central Avenue, East Molesey, Surrey, KT8 OQZ. Membrane Filtration Syringe A re-designed version of the Antlia pneumatic syringe pump for pressure filtration has thicker walls in the syringe body and easier pumping action. It finds application where pressure filtration with membrane filters is required on a small scale. Anderman & Company Ltd., Central Avenue, East Molesey, Surrey, KT8 OQZ.Dosing Pump A range of 14 pump types with capacities from 0-401h-l to 0-19001h-1 are made of boro- silicate glass casings and PTFE plungers and valves. The standard equipment of dosing pumps designed for operating temperatures of up to 100 "C includes stroke adjustment and an explosion-proof motor as well as a priming device for the pump head.Jenaer Glaswerk Schott, Hattenbergstrasse 10, D6500 Mainz, West Germany. Sample Injector The Autojector Mk. I1 sample injector is an improved model that extends its usefulness across a wider range of syringes. For use withJuly, 1979 EQUIPMENT NEWS 213 flanged syringes the unit is now supplied with two interchangeable barrel sleeves, one for syringe diameters up to 7 mm, e.g., Terumo MS and UMS, Hamilton 701 and Kloehn Triple-0 series, and another for barrel diameters 7-8.2mm, e.g., Hamilton 710 and 7001 and Kloehn Micro-Fit types.A third design of barrel sleeve is available for use with plain (unflanged) syringes with diameters of approxi- mately 8 mm, e.g., SGE. Clandon Scientific Ltd., Lysons Avenue, Ash Vale, Aldershot, Hampshire, GU12 5QF.Leak Detector - Gas Chromatograph The battery-operated, portable, combined, continuously-sampling gas-leak detector and gas chromatograph incorporates a high sensi- tivity electron-capture detector and uses sulphur hexafluoride as the tracer gas, with the column in the gas chromatograph specific to sulphur hexafluoride.This combination permits 1 part of hexafluoride in 10l1 parts of air to be detected. The detector, chromatograph, associated electronics and the rechargeable batteries are contained in a single unit, which is mounted inside a carrying frame with the controls located under a transparent cover. A1 Industrial, London Road, Pampisford, Cambridge, CB2 4EF. Pumping System for HPLC The Micromeritics 750 solvent delivery system is a dual-piston, reciprocating design, incorpor- ating a hypercompensated cam and electronic flow multiplexing synchronisation in order to achieve a high degree of flow precision, typically better than &0.50% a t flows from 0- 20 ml min-l and pressures to 6000 lb in-2.The 750 system is universally adaptable to other HPLC components and can be upgraded to microprocessor control.Micromeritics Instrument Corporation, 5680 Goshen Springs Road, Norcross, Ga. 30093, USA. Carbohydrate Analysis HPLC Columns HPLC Columns are available in two sizes, 300 x 7.8mm and 250 x 4mm, filled with Aminex Carbohydrate HPX87 resin. They are designed to suit the requirements of the brewing and foocl industries and are applicable to a variety of carbohydrate analysis problems that require high resolution and high speed separa- tion.The columns are constructed of Lichroma ID Type 316 stainless-steel tubing. Bio-Rad Laboratories Ltd., Caxton Way, Holywell Industrial Estate, Watford, Hertford- shire, WDl 8RP. Microprocessor Based HPLC System The Micromeritics 7500 system, an integrated liquid chromatograph system, incorporates a microprocessor-based 740 control module.In addition to a chromatogram, the printout gives gradient - solvent conditions, flow-rate, pressure, temperature and operational status. Automation of the 7500 system is achieved by the Micromeritics 725/726 autoinjector. Other 7500 system components include a 753 ternary solvent mixer, a precision heated column compartment universal injector and a choice of detectors, including the 786 variable wave- length detector, the 791 fixed wavelength detector and the 771 RI detector.Micromeritics Instrument Corporation, 5680 Goshen Springs Road, Norcross, Ga. 30093, USA. Desk-top Computer The System 35 makes available the memory size (64-256 kbytes) and input/output capabili- ties of a mini-computer in a desk-top size, employing enhanced BASIC language.Hewlett-Packard Ltd., King Street Lane, Winnersh, Wokingham, Berkshire, RG11 5AR. Laboratory Data Systems A family of laboratory data systems, the LDS Series, has been introduced for use in the characterisation of synthetic and biopolymers. This new series provides real-time processing of gel-permeation chromatography data, rela- tive molecular mass, relative molecular mass distributions, diffusion coefficients and mole- cular size. The systems consist of Chromatix developed software in disc form plus the Digital Equipment Corporation LSI-11 micro- computer, part of the PDP-11 family, operating under Digital’s RT- 11.LDS-1, intended for general purpose labora- tory use, includes Digital RT-11 software, system discs, an LSI-11 microcomputer with a 20k RAM memory, dual floppy disc drive, hardware multiply - divide and a printer - plotter.The LDS-2, designed for polymer characterisation employing a gel-permeation chromatograph (GPC) or a combined system with a GPC and a KMX-6 light scattering photometer, includes the same elements of the LDS-1 system, plus a two-channel analogue to digital interface for GPC and light-scattering detectors.Two separate disc-based software programmes are available, one for GPC, the other for GPC and light scattering.214 EQUIPMENT NEWS Proc. Analyt. Div. Chem. SOC. The LDS-3 is designed for diffusion co- efficient and molecular size applications in the study of biopolymers, using the KMX-6 and a digital correlator, such as the Chromatix hlodel 64.It consists of software for these para- meters, the same system elements as LDS-1, plus a serial interface for a digital correlator Other options for the LDS series include BASIC and FORTRAN software, two channel analogue to digital interface, and serial input/ output interface. A kit is available to convert the Chromatix KMX-6/DP Molecular Weight (relative molecular mass) Data Processor to an LDS-2 or -3. Rofin Ltd., Winslade House, Egham Hill, Egham, Surrey, TW20 ORZ.output. Tunable Laser The ESDI is a compact, bench top tunable laser source, which covers the range 400-700 nm. The system includes a pulsed nitrogen laser for pumping and a dye laser, which has an output of 30 pJ a t 25 Hz, peak power of 10 kW or greater and spectral line width of approxi- mately 1 nm.Glen Creston Instruments Ltd., 16 Carlisle Road, London, NW9 OHL. Differential Refractometer A differential refractometer using a laser as a light source, the KMX-16, incorporates a coherent laser source that provides signifi- cantly greater beam collimation than mercury or tungsten light sources. The sensitivity is improved ten-fold, to 2 x lo-' refractive index units.The temperature range is from -10 to + 165 "C and the reproducibility specified as 1 x refractive index units. Rofin Ltd., Winslade House, Egham Hill, Surrey, TW20 OAZ. Recorders The Series 50000, available in standard formats plus an OEM version, has a slewing speed of a t least 250 cm s-l with a O-lOO% full-scale pen excursion in 160 ms for the A3 size Y axis, while maintaining a maximum axial overshoot of 1 mm.The mainframe will accept multi- range amplifiers with sensitivities from 50 pV cm-l and single range amplifiers from 1 mV cm-l while the servo system is protected by an automatic electronic safety circuit. Size A4 charts can be used on an A3 frame and the paper hold-down system can be either magnetic strip, vacuum or electrostatic.Bryans Southern Instruments Ltd., Willow Lane, Mitcham, Surrey, CR4 4UL. Recorder A recorder suitable for battery or mains opera- tion is available for horizontal or vertical rack or wall mounting. With a wide range of chart speeds, it can accept roll or fan-fold chart paper with single- or two-pen operation. J. J . Lloyd Instruments Ltd., Brook Avenue, Warsash, Southampton, SO3 6HP.Amplifier The 2300 Series multi-channel amplifier and signal conditioning system can deliver three simultaneous buffered outputs and a playback mode to filter from previously recorded magnetic tapes, with excitation from 0.5 to 15V d.c. and operation exceeding 25 kHz. Welwyn Strain Measurement Ltd., Arm- strong Road, Rasingstoke, Hampshire, IiG24 OGA.Freeze-etching Accessory A rotary cold stage makes possible the conical shadowing or rotary replication of freeze- etched samples. This technique is particularly useful to the electron microscopist in the field of membrane research, making it possible, for example, to resolve small membrane particles into their sub-units. This rotary cold stage can also be used for the conical shadowing of DNA and RNA molecules, etc.Balzers High Vacuum Ltd., Northbridge Road, Herkhamsted, Hertfordshire, HP4 1EK. Literature A leaflet describes the new Countapart System, designed to connect to any Oertling electronic balance with BCD output. Oertling Ltd., Orpington, Kent, BR5 2HA. The December 1978 number of the Hewlett- Packavd Journal features articles on the use of a microprocessor-controlled digitiser to speed up the transfer of positive information from maps, slides, photographs, etc., into a computer for analysis.Other articles describe the use of a logging multimeter to manipulate data, and the use of a 1-50MHz signal source to provide test stimuli for automatic or bench-test appli- cations. Hewlett-Packard S.A., P.O. Box 529, Van Heuven Goedhartlaan 121, Amstelveen 1 134, The Netherlands. A pamphlet describes the range of analytical instruments available from Hewlett-Packard Ltd., P.O.Box CH-1217, Meyrin 2, Geneva, Switzerland.July, 1979 ANALYTICAL CHEMISTRY I N UK UNIVERSITIES 215 The November, 1978, edition of Gallenkavnp News and Review features the System M range of laboratory furniture, together with other recent additions to the range of laboratory equipment. A.Gallenkamp & Co. Ltd., P.O. Box 290, Technic0 House, Christopher Street, London, ECZP 2ER. The November - December, 1978, edition of the News pamphlet features System 35, a desk top computer, the 8901-A modulation analyser, other new interface boards and a fibre-optic link. Hewlett-Packard Ltd., Winnersh, Wokingham, Berkshire, RG11 5AR. A series of booklets under the following headings are available : Patch Test Kit; Gravimetric Analysis ; Fluid Sampling Kit for Gravimetric and Patch Testing Analyses ; Particle Counting Analyses. A comprehensive manual on ultra- filtration is also available. Millipore (UK) Ltd., Millipore House, Abbey Road, London, NWlO 7SP. A booklet entitled “Filtration in the Chemical Laboratory” has been prepared by Schleicher and Schuell of Dassel, Germany. Anderman & Co. Ltd., Central Avenue, East Molesey, Surrey, KT8 OQZ. A second edition of “Measuring Colour” has been produced. Tioxide International Ltd., 10 Stratton Street, London, W1A 4XP. The complete Oxford range of disposable pipette tips is described in a pamphlet. BCL, Bell Lane, Lewes, East Sussex, BN7 ILG. A complete “spillage” kit for laboratories, the range of pH papers, Lancer glassware washing machines, Vitrex disposable micropipettes, and Peristaltic pumps, are described in a series of pamphlets. A booklet entitled “Data on Hazardous Chemicals” is also available. Cam- lab Ltd., Nuffield Road, Cambridge, CB4 ITH. A pamphlet describing impedance measuring instruments is available. Hewlett-Packard Ltd., P.O. Box 85, CH 1217, Meyrin 2, Switzerland.

ISSN:0306-1396    

DOI:10.1039/AD9791600211

出版商:RSC    

年代:1979

数据来源: RSC

摘要:

July, 1979 ANALYTICAL CHEMISTRY I N UK UNIVERSITIES 215 Analytical Chemistry in UK Universities, Polytechnics and Colleges This article is the third in a series that describes current activities in analytical chemistry depart- ments and sections in UK Universities, Poly- technics and Colleges. It is hoped that the details that will be given of individual projects being undertaken by the various members of staff in each establishment will be of use to analytical chemists elsewhere and will help to generate contacts between workers in similar areas who may be unaware of research being carried out within their own sphere of interest.As far as possible the names of staff and their current research activities will be detailed in order to facilitate personal contacts.Several articles have been invited so far and are being published a t intervals; however, con- tributions from any departments with an inter- est in analytical chemistry are welcome and should be sent to the Editor, who will also be pleased to advise on the general content of the articles. Analytical Chemistry at The Polytechnic, Wolverhampton In this Polytechnic the Department of Physical Sciences, headed by Dr.J . V. McLaren, caters for a large number of students based in local industry and studying chemistry a t levels ranging from HNC to first degree and postgradu- ate levels. Analytical chemistry is well repre- sented in the part-time BSc Degree in Applied Chemistry and there are well-established Post- graduate Diploma and MSc courses in the sub- ject.There are currently 23 students enrolled on these postgraduate courses. Close liaison of the Polytechnic with local industry has resulted in a considerable develop- ment of consultancy work carried out by the Department of Physical Sciences within the last few years. Within the Department, the Physical and Analytical Section headed by Dr. D. R. Crow consists of nine staff of whom the following have active research interests, either specifically in Analytical Chemistry or more generally as related to fundamental studies in Physical Chemistry : D.R. Crow, Principal Lecturer; R. G. Anderson, Principal Lecturer, G. Boden, G. Brumfitt, K. Miller and D. A. E. Rendell, Senior Lecturers. Further, there are staff in216 ANALYTICAL CHEMISTRY IN UK UNIVERSITIES Proc.Analyt. Div. Chem. SOC. other sections of this and other departments who are engaged in various analytical research programmes. Dr. Crow joined the Department in 1973 from Thames (formerly Woolwich) Polytechnic. Al- though a physical chemist, concerned primarily with both theoretical and practical aspects of the electro-reduction mechanisms of metallic com- plexes, he has made contributions to the literature concerned with electrochemical analy- sis.He is the author of “Polarography” (with J . V. Westwood), “Polarography of Metal Complexes,” “Polarographie” (in French, with J. V. Westwood) and “Principles and Applica- tions of Electrochemistry” (now in its Second Edition). Current research interests include : studies of migration of molecular and ionic species through polymer membranes (with Dr.G. Boden and Miss Asha Gogna), factors affecting the unique voltammetric behaviour of the Ki(I1) ion (with Dr. G. Brumfitt, M. E. Rose, G. Darlington and L. Price), the electro- chemical investigation of metal - ligand equi- libria, determination of rates and mechanisms of electrode processes and the development of new indicator electrode systems.Dr. R. G. Anderson, who worked on the development of electrothermal techniques for atomic absorption with Professor T. S. West a t Imperial College, London, is currently engaged in developing new analytical methods using atomic absorption, particularly with solvent extraction. He is also interested in the mass- spectrometric analysis of drugs. Earlier studies by Dr.K. Miller of the auto- matic interpretation of lH nuclear magnetic resonance spectra using a digital computer have lead (with R. Jones) to investigation of the automatic prediction of nuclear magnetic resonance spectral details (now extended to 13C) from a chemical structure, or structure repre- sentation, used as a computer input. Currently, effort is aimed a t the application of micro- processors as controllers for chemical and physical processes (with Mr.J. E. Willett). Dr. J . V. McLaren, the Head of Department, is engaged in a collaborative study, with the National Coal Board, of the gel-permeation chromatography of oligomers (with R. Taylor). The analysis of boron in steels and fluorescent complexes of boron is a current major interest of Dr. D.A. E. Rendell (with D. Donnelly). Further investigations are the interpretation of vibra- tional spectra of complex ions (with M. Perry), use of the pyrolysis technique in infrared spectroscopy (with D. Dodd), use of spectro- scopic methods in the study of plastics (with D. M. Jacks) and semi-quantitative analysis using the large quartz spectrograph and arc excitation with powdered samples (with J.Barton). The application of analytical tech- niques to problems with a more biological bias is the concern of several staff, notably Dr. J. J . Cox. He is studying the behaviour of heavy metals in soils and in plants, in particular the uptake of heavy metals by plants (with C. Moore) and the behaviour and fate of heavy metals in the treatment of sewage by the activated sludge process (with P.Garratt). Drs. I. C. Trueman and C. B. Clarke (both of the Department of Biological Sciences) are currently investigating the biological activity of airborne lead using the techniques of atomic absorption and X-ray fluorescence and diffraction (with D. Atkcins). In collaboration with the Midlands Associa- tion for Qualitative Analysis, Dr. B. W. Rockett and Dr.G. Marr are engaged in the development and evaluation of systematically reliable qualitative tests for selected inorganic species. Drs. Rockett and Marr are joint authors of “Practical Inorganic Chemistry.” Dr. Marr is also engaged, in collaboration with Dr. R. Eptm (Reader), in the preparation and evalua- tion of supports for gel-permeation chromato- graphy, which can be used with both aqueous and non-aqueous solvents. A growing amount of consultancy work in analytical chemistry is undertaken by the Department as related to the problems of local industry. Of particular significance in this respect is the work of Dr. C. D. Whiston, who oversees the application of X-ray fluorescence and X-ray powder techniques in a wide variety of analyses. It is hoped that this brief review of current work and interests will give some indication of the commitment of this Polytechnic to the increasingly significant applications of analytical chemistry. D. R. Crow Department of Physical Sciences, The Polytechnic, Wolverhanzpton, W V 1 1 L Y

ISSN:0306-1396    

DOI:10.1039/AD9791600215

出版商:RSC    

年代:1979

数据来源: RSC

摘要:

July, 1979 OBITUARY 217 Correspondence Correspondence is accepted on all matters of interest to analytical chemists. Letters should be addressed to the Editor, Proceedings of the Analytical Division, The Chemical Society, Burlington House, London, W1 V OBN. Definition and Priorities of Chairs in Analytical Chemistry Sir, The recent article1 on R. M. Caven raises the questions of the definition and the priorities of Chairs of Analytical Chemistry in the United Kingdom of Great Britain and Northern Ireland and in Ireland as a whole.Various definitions can be given for the term “Professor”; the most authoritative is probably that in the NED,2 the appropriate portion being I1 4: “A public teacher or instructor of the highest rank in a specific faculty or branch of learning; spec.one who holds an endowed or established chair in a university or one of its colleges. Also fre- quently applied to the tutors or lecturers on the staff of theological and other professional or technical colleges, academies and seminaries. ” Caven’s3 title derives from the University of Glasgow, for from 1912 the college founded under thc will of John Anderson was known as the Royal Technical College Glasgow, and was affiliated with the University of Glasgow in 1913.Further, it was recognised by the U.G.C. and placed on the list of university institutions receiving a grant from the Treasury in 1919.4 Other colleges running degree courses for uni- versities have also had heads of department with university-granted titles of Professor, e.g., West of Scotland Agriculture College, Belfast College of Technology ; notable exceptions were the London colleges which ran London internal degree courses via the “Recognised Teacher” scheme.Academies are also allowed “Chairs” under the NED definition.2 Possibly the most famous example of such a body is the Royal Institution of Great Britain,5 of which Professor Sir George Porter is the present Fullerian Professor of Chemistry.6 Porter and his predecessors Davy, Faraday, Tyndal, Dewar and Bragg are cert- ainly of the highest rank or quality in their218 A D DISTINGUISBED SERVICE AWARD branches of learning.On these grounds, the chair of Analytical Chemistry of the Royal Dublin Society held by James Emerson Reynolds7-9 was the first in these islands. The title Professor can also be “assumed as a grandiose title by professional teachers and exponents of various popular arts and sciences.” Thus, the title should not be accepted or indeed used in Colleges not of University rank or affiliation unless it is clearly seen that those to whom the title is given are of the highest level of achievement and recognised, both at home and abroad, as such.References 1. Belcher, R., Proc. Analyt. Div. Chem. SOC., 1979, 16, 175. 2. Murray, J. A. H., Editor, “A New English Dictionary on Historical Principles,” Volume VII, Part 11, Clarendon Press, Oxford, 1909, p. 1428. Professor Belcher replies as follows- I think the main difficulty arises from the very loose usage of the title “Professor” in the English language. In the USA the term is used for all university and college staff and even for school- teachers; when I was a child, I remember there were Professors of Fencing, Dancing, etc.Perhaps that is not surprising in a country which, until 1922, allowed anybody without qualifications, training or experience, to set up as a dentist. I was careful to state “the 20th century definition” and if this is kept in mind, I consider that Professor Burns’ argument is not tenable.The NED was published in 1909 and the author would have been using 19th century definitions. The most important argument advanced by Professor Burns is the existence of the Fullerian 3. 4. Cumming, W. M., J . Chem. SOG., 1934, 1469. University of Strathclyde in Springer, H. W., Craig, T., and Archer, E.A., Editors, “Common.u~ealth Universities Year Rook 1979,” Association of Commonwealth Universities, London, 1979. 5 . British Council, Editors, “Scientific and Learned Societies of Great Britain,” 61st Edition, G. Allen and Unwin, London, 1964. 6. “Who’s Who 1978,” A. and C. Black, London, 1978. 7. Thorburn Burns, D., Proc. Analyt. Div. Chem. Soc., 1977, 14, 171. 8. Thorburn Burns, D., and MacDaeid, D., Orbital, 1978 ( 2 ) , 14.9. Thorburn Burns, D., Lecture given at Euro- analysis 111, Dublin, 1978. D. Thorburn Burns Department of Chemistry, The Queen’s University of Belfast, Belfast, BT9 5AG, Northern Ireland Professorship a t the Royal Institution. But this was a 19th century installation and, in any case, involves direction of a research staff. The appointment, therefore, is more in keeping with a university post than that held by Reynolds. I am not clear whether Reynolds was simply given the title, or if the appointment was termed a “Chair.” If only the former, then I acknowledged his priority in my article, but even if it was the latter, it does not accord with the 20th century definition. I have great respect for Professor Burns’ scholarship and his ability to unearth unusual and odd historical information, but he has failed to convince me that the first Chair in the United Kingdom, associated with Analytical Chemistry was held by any other than R. M. Caven.

ISSN:0306-1396    

DOI:10.1039/AD979160217b

出版商:RSC    

年代:1979

数据来源: RSC

摘要:

218 A D DISTINGUISBED SERVICE AWARD Ana I yt ica I Division Distinguished Nominations are invited for the Division’s Distinguished Service Award, the Rules for which are as follows: 1. The aim of the Award is to recognise exceptional service over a period of years to the Analytical Division of the Chemical Society (including that to the Society for Analytical Chemistry). 2. The Award shall normally be in the form of an illuminated address which may be accompanied by such additional recognition as Council of the Division shall agree.3. Nominations for the Award will be invited annually from members of Council of the Division, and may be received from any Service member of the Division. They shall be made in writing, with supporting evidence, to the President of the Analytical Division.4. Nominations shall be considered by the Honours Committee of the Analytical Division, which shall recommend to Council of the Division (a) to whom an award should be made, ( b ) the nature of the award or (c) that no award should be made. 5. The Award shall be made by the Council of the Analytical Division, which must ap- prove any alteration of these Rules. Nominations for the Award should be sent to the President of the Analytical Division before September 15th, 1979. Printed by Heffers Printers Ltd Cambridge England

ISSN:0306-1396    

DOI:10.1039/AD9791600218

出版商:RSC    

年代:1979

数据来源: RSC