摘要:

Proceedinas - - - - ~of the Analytical Division ofThe Chemical Society1491491491 54156162169172172173174CONTENTSReports of MeetingsSummaries of Papers'How to Attack Your Sample!''Lasers and Their Analytical'Use of the Microscope'Applications'Equipment NewsAnalytical Chemistry in UKUniversities, Polytechnics andCollegesRobert Boyle Essay AwardsPublications ReceivedCoursesAnalytical Division DiaryVolume 16 No 5 Pages 149-1 74 May 197PADSDZ 16(5) 149-1 74(1979)ISSN 0306-1 396May 1979PROCEEDINGSOF 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.1. Coomber, O.B.E.; D. C. M. Squirrel1Sscretar y 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,Letchworth, Herts., SG6 1HN.Non-members can only be supplied with Proceedings as part of a combined subscription with The Andyrtand Analytical Abstracts.@ The Chemical Society 1979Annual Reports on AnalyticalAtomic SpectroscopyVOLUME 7, 1977This comprehensive and critical report of developments in analytical atomicspectroscopy has been compiled from over 1700 reports received from world-wide correspondents who are internationally recognised authorities in the fieldand who constitute the Editorial Board. In addition to survey; ng developmentsthroughout the world published in national or international journals, a particu -lar aim has been to include less widely accessible reports from local, nationaland international symposia and conferences concerned with atomic spectros-COPY.(Still available: Vols 3-6 covering 7973 to 7976)Clothbound 30Opp 8;" x 6" f 17.50 (CS Members f 13.00)Obtainable from : The Chemical Society, Distribution Centre,Blackhorse Road, Letchworth, Herts., SG6 I H

ISSN:0306-1396    

DOI:10.1039/AD97916FX017

出版商:RSC    

年代:1979

数据来源: RSC

摘要:

Analytical Division DiaryMAYThursday, 31st, 6.30 p.m. : NottinghamMidlands Region.“Luminescence Analysis of Drugs,” byJ . N. Miller.Lecture Theatre, The Boots Co. Ltd.,Pennyfoot Street, S’ottingham.JUNEWednesday, 6th, 11 a.m.: WareBiological Methods Group : Summer Meeting.Visit to Glaxo-Allenburys <Research Labora-tories, Ware, Herts.Wednesday, 6th, 2 p.m. : LoughboroughElectroanalytical and Education and TrainingGroups, joint meeting on “Why TeachElectroanalytical Chemistry ?”“The Teaching and Importance of Polaro-graphy,” by A. G. Fogg.“Potentiometry,” by J . D. R. Thomas.“Why Use Electroanalysis ?” by R. Rooney.Chemistry Department, University of Tech-nology, Loughborough, Leicestershire.Thursday and Friday, 7th and 8th, Stirling,Vorth West, Scottish and North East Regions,with the A utomatic Methods and .JointPharmaceutical Analysis Groups and theScottish Region of the Industrial Divisionon “Analytical Quality Control.”Tliursday, 7th, 9.25 a.m.-Plenary Lecture: “I Analyse; You Assess;He, She or It Controls,” by C.A. Johnson.Statistical Aspects of Quality AssurancePlenary Lecture: “The Analyst and theStatistician,” by Professor A. R. Rogers.“Cumulative Sum Techniques,” by J . D.Chamberlain.“Acceptance Sampling,” by R. Caulcutt.A utomatic Methods and Quality ControlPlenary Lecture : “The Impact of Automationon Quality Control,” by T. E. V. Horsley.“Practical Considerations in the AnalyticalUse of Microprocessors,” by D. Betteridge.“Automated Pharmaceutical Quality ControlTTsing AutoAnalyzers : One Company’s“Analytical Quality Control as an Aid forManagement of an Automated Laboratoryfor Cigarette Smoke Analysis,” by G.K. E.Copeland.Friday, Sth, 9.15 a.m.-Legislation and Case Studies in A nalyticalQuality ControlPlenary Lecture .+ “EEC Legislation : Is Therea Need for Quality Control?” by R.Sawyer.“The Quality Control of Beers and Lagers,”by P. M. Carpenter.“The Quality Control of Wines,” by MissA. J . Fishlock.“The Quality Control of Plastics in Pharma-ceutical Packaging,” by J. E. Pentelow.Plenary Lecture : “A New Systematic Appro-ach to the Control of Accuracy and Pre-cision in Routine Analysis,” by ProfessorG. Ghersini.“‘Trouble a t t’Mill: Somc Problems in theAssay of Animal Feedstuff Additives,”by T. C. Forster.“Our Results are Right, Give or Take aLittlc,” by G. A. Best.Pathfoot Building, The University, Stirling.Saturday and Sunday, 16th and 17th,BuxtonNorth West Region : Summer Meeting.“Minerals of the Peak District,” by J . H.“Peak District Calendar,” by R. Woodall.Palace Hotel, Buxton.Harwood.Wednesday, 20th, 2 p.m.: LondonExtraordinary General Meeting of the Analy-Royal Institute of Chemistry, 30 liusselltical Division.Square, London, W.C. 1 .Wednesday, 20th, 6 p.m.: LondonSouth East Region.“Present and Future Role of Public Analy-Linnean Society, Burlington House, Picca-sts,” by A. J. Harrison.Experience,” by D. E. Faulkner. dilly, London, W.l

ISSN:0306-1396    

DOI:10.1039/AD97916BX019

出版商:RSC    

年代:1979

数据来源: RSC

摘要:

Vol. 16 No. 5 May 1979 How to Attack Your Sample! The following are summaries of two of the papers presented at a Meeting of the Microchemical Methods and Special Techniques Groups held on November 28th, 1978, at the Scientific Societies Lecture Theatre, 23 Savile Row, London, W.l. Development and Applications of High Temperature, High Pressure Dissolution in a Sealed Tube D. Crossley Chemistry Division, A ERE, Harwell, Didcot, Oxfordshire The high temperature, high pressure method of dissolution in a sealed tubel was developed at AERE Hanvell for the dissolution of ceramic materials containing plutonium.Various 149150 HOW TO ATTACK YOUR SAMPLE! Proc. Analyt. Div. Chew. SOC. mixtures of plutonium dioxide with oxides of other metals have been investigated as potential nuclear fuel materials and samples of these materials, when submitted for analysis, present a considerable dissolution problem.Plutonium dioxide, when heated above 1000 "C, becomes very refractory and is very difficult to dissolve completely by conventional methods. Fusion methods2s3 have been developed for the dissolution of highly fired plutonium dioxide and mixtures of plutonium dioxide with other metal oxides or metals, but fusion techniques are not entirely satisfactory for a number of reasons.A fusion introduces large amounts of unwanted salts into a sample solution, which may lead to difficulties under some circum- stances. There is a risk of contamination in trace-element analysis, a risk of loss of a volatile element during the fusion and the dissolution of the sample may not be completed in one step as often a residue has to be separated and re-treated.The sealed-tube method of dissolution completely overcomes these problems and is based on the observation that many refractory materials that are essentially insoluble in acids at temperatures limited by their boiling-points may be completely dissolved at the higher temperatures obtainable in a sealed tube at high pressure.The pressure developed in a tube at a temperature of 300 "C may be as high as 4 000 lbf in-2, therefore steps must be taken to prevent the silica tube from bursting. This is achieved by placing the tube in an autoclave, which can provide a suitable compensating pressure. This technique of dissolu- tion had not been previously used at Harwell because of some apprehension concerning the safety of the method for use with radioactive material.The recommended technique for providing the compensating pressure i.n the original method4 was very crude and exceedingly dangerous when using a sealed bomb with no indication or control over the pressure. The first stage in the development of the method for use with plutonium ceramics was the design and production of an autoclave that could be safely and easily operated within the confined space of a glove box used for handling a-active materials. The autoclave produced and successfully used in the dissolution work is small, approximately 330 mm tall, 80 mm in diameter, with a 40 mm bore and made of stainless steel.It is fitted with a pressure gauge, pressure release valve and a bursting disc safety device that operates at a pressure of 5 000 lbf in-2. The autoclave and heater are enclosed in a water-cooled jacket and the maximum operating pressure at a temperature of 300 "C is 6 000 Ibf in-2.The autoclave is sealed by applying the relatively low torque of 25 f t lb to each of six screws that bear on a plug, which has a copper gasket between it and the seat of the autoclave body.The tem- perature of the autoclave is controlled by an electrical control unit, which also switches off the electrical supply to the heater if the pressure should rise above 4 500 lbf in-2 or if the flow of cooling water should fail. The control unit also has a delay clock to switch off the heater a t a pre-set time.In order to carry out the dissolution of a sample a weighed portion of the sample (50-250 mg) is washed into a silica sample tube with 2 ml of hydrochoric acid and 0.25 ml of nitric or perchloric acid if required. The silica sample tube has the dimensions 230 mm long, 5-6 mm bore and 2-2.5 mm wall thickness, and is sealed at one end with a constriction 50 mm from the open end.The tube is then immersed in a slurry of trichloroethylene and powdered carbon dioxide to a depth of about 100 mm. After a few minutes the tube is sealed off by heating the constriction with an oxygen and town or natural gas torch. Up to four sample tubes can be placed in the brass autoclave liner. Approximately 1OOg of powdered carbon dioxide are added to the liner, the lid is then fitted, and the liner placed in the autoclave.The autoclave is next sealed and heated to 300 "C. During the heating-up period excess carbon dioxide is released from the autoclave via the valve so as to maintain a pressure of 4 000 lbf in-2. After a suitable dissolution time, usually an overnight period, the autoclave is cooled to room temperature, the gas pressure released and the sample tubes removed.If the dissolution of the sample is complete the tube can be opened by first cooling in a slurry of trichloroethylene and solid carbon dioxide and then cracking the top of the tube off in a simple opening device. The contents of the tube are allowed to thaw and run into a beaker. Subsequently the tube and seal are washed with water and the washings are added to the sample solution, which can then be made up to volume and used in the analysis required.Table I lists a variety of materials that have been dissolved by the method described. The solvent and the approximate time required are indicated. The table is not an exhaustive list of materials that can be dissolved by the method; there are undoubtedly many other applications.May, 1979 HOW TO ATTACK YOUR SAMPLE! TABLE I CONDITIONS FOR THE DISSOLUTION OF VARIOUS REFRACTORY MATERIALS 151 Material and condition ,4lumina-Ground sintered material Lump sintered material Calcined, analytical-reagent grade Thorium oxide-Fired a t 2 000 "C Zirconium oxide-Fused, ground t o < 100 mesh Magnesium oxide-Powder, analytical-reagent grade Iron(II1) oxide-Fused Ru thenium-Spec Pure powder Iridium-Spec Pure powder Osmium-Spec Pure powder Rhenium-Spec Pure powder Rhodium-Spec Pure powder Vanadium pentoxide-Analytical-reagent grade Boron carbide-700-1000 pm shot Plutonium dioxide-Arc melted Acid solvent HC1 HC1 HC1 HCI- HNO, HC1- HNO, HC1- HNO, HC1- HNO, HCl- HNO, HC1- HNO, HC1- HNO, HCI- HNO, HCI - HNO, HC1 HNO, HC1 Heating period/h 5 10 15 5 10 5 5 10 5 5 5 17 24 18 16 References 1.2 . 3. 4. Crossley, D., and Milner, G. IV. C., U.K. Atomic Enevgy Authority Report AERE R-6217, HM Stationerv Office, London, 1969. Milner, G. IV. C., Wood, A. J . , Weldrick, G., and Phillips, G., Analyst, 1967, 92, 239. Milner, G. W. C., and Crossley, D., Analyst, 1968, 93, 429. Wickers, E., Schlecht, W. G., and Gordon, C. L., J .RCS. Nat. Bur. Stand., 1944, 33, 363 and 451. The U s e of Fusion Fluxes G. J. Oliver The British Ceramic Research A ssociation, Queens Road, Penkhull, Stoke-on-Trent, ST4 7LQ When analysing ceramic materials, or for that matter geological materials, one has to break the samples down in some way. This breakdown often involves a fusion process, and it has to be carried out whatever the final method of analysis might be. This paper is primarily con- cerned with the preparation of samples for analysis by the most commonly used analytical techniques in ceramics, viz., conventional wet chemical methods, X-ray fluorescence, atomic absorption, flame emission and direct reading spectrometry.Fusion as such is very simple; if the analyst takes a small enough amount of sample, a large enough amount of flux and uses a high enough temperature it is possible to decompose just about anything. The analyst must ask more of the flux than just a means of decomposing the sample.The flux must be considered as an integral part of the whole scheme of analysis and he must ask the following questions: What are the particular peculiarities with regard to fusion of the class of material we are analysing? What does he intend to do with the sample when it is fused? Taking the first question it is necessary to decide which oxides in the sample will cause problems, whether they are difficult to fuse (like zirconium oxide), or volatile (like selenium oxide), or will react and alloy with the platinum dish (like cobalt oxide).Having decided on a flux, it is often possible to find the correct sample to flux ratio by writing down the chemical reaction that is likely to occur during the fusion process.If it is intended to carry out trace element determinations, then one has to use the maximum amount of sample and the minimum amount of flux; if possible it is better to use no flux at all. If a flux has to be used, it should be as pure as possible.This not only means choosing the purest grade of flux, but also the composition of the flux: sodium peroxide tends to be impure and should be avoided for trace work; sodium carbonate should be used in place of fusion mixture as the former is purer; lithium tetraborate can be used in preference to lithium metaborate for the same reason. When macro-scale analysis is to be performed then the whole scheme of analysis must be considered; are aqueous solutions being prepared, as is the case with wet chemical, atomic- absorption and direct-reading techniques, or will glass beads be used, as is the case in X-ray fluorescence analysis (XRF) ? If solutions are being used, is a gravimetric silica determination Now to the second question. What must be done with the sample after it is fused?152 being carried out or must the silica be retained in solution in a stable form? trates these points.HOW TO ATTACK YOUR SAMPLE! Proc. AnaZyt. Div. Chem. SOC. Table I illus- TABLE I REQUIREMEKTS OF FUSIOF TECHKIQVE \Vet chemical Direct Atomic X-ray Requirement analysis reading absorption fluorescence Cravimetric silica .. . . . . bf Stablc solution . . . . . . d Rapid dissolution of melt . . . . J Good glass . . .. . . . . x Clear melt* . . . . . . 1 . J (Silica in solution . . . . - . x * Where a melt is formed. In wet chemical analysis the silica is removed from solution, whereas for instrumental methods it must be retained in solution if it is to be determined. A good glass is necessary only for XRF where the bead must not shatter on storage.For this technique we have the advant- age of a one-stage process. For the other techniques we have to incorporate into our flux a means of rapid dissolution (usually excess carbonate). A rapid dissolution is required because at that intermediate stage between basic flux and acid solution precipitation and polymerisa- tion can occur.The requirement of a clear melt for wet chemical analysis is to be sure that the sample is totally decomposed by the flux. The role of the flus as an integral part of the analy- sis will be expanded by discussing chemical techniques, instrumental solution techniques and XRF in turn. These fluxes have been described by Bennett and Reed [Chemical Methods of Silicate 4nalysis (13CRA4), Academic Table I1 shows some fluxes that are used for wet chemical analysis.Press, London and New York, 19711. Material type Aluminosilicate-high silica Aluminous .. , . Frits and glazes Zircon bearing . . .. (a) Main analysis . . (b) B 0 determination Lead bi%ate . . * . White opacificd glaze . . Chrome bearing (a) Main analysis . . (b) SiO, determination (c) Cr,O, determination Magnesites - dolomites Liinestonc - bone ash } TABLE I1 FLUXES ITOR WET CHEMICAL ANALYSIS Sample Fusion mass/g misturelg .. .. . . 1 3 . . . . . . 1 1.5 . . . . . . 1 3 . . .. . . 1 3 . . . . . . 0.5 10 . . . . . . 1 . . . . .. 1 _- - .. . . . . 1 S .. . . 0.1 4 . . . . . . 0.26 4 S 3 Jiu :n Boric acid/g carbonate/g 0.4 - 0.2 - 2 - .. . . . . Acid dissolution _- 4 2 2 .- - The flux for aluminosilicate and high silica materials has been designed with both the need for a rapid fusion and also a gravimetric silica determination in mind.There is sufficient fusion mixture both to convert the silica to the alkaline silicate and to allow an excess of carbonate to assist in dissolution. The boron(II1) oxide assists in the fusion of silica by glass formation.For aluminous materials less fusion mixture and less boron(II1) oxide are re- quired because of the lower silica content. This latter flux does not, in fact, produce a melt but a sinter, which is easily dissolved in acid because of its large surface area. Zircon-bearing materials require more fusion mixture and boric acid because zirconium oxide does not fuse readily.With glazes boric acid is not required because the sample already contains boron(II1) oxide; lead bisilicates, on the other hand, do not contain it. Alkalis are determined by attack with hydrofluoric acid so the presence of alkalis in the fusion mixture is unimportant. The flux is designed so that with the sample at 1200 "C itMay , I9 79 HOW T O ATTACK YOUR SAMPLE! 153 gives a clear melt, demonstrating complete decomposition.On addition of acid to the melt in the platinum fusion dish the excess carbonate ensures rapid dissolution, and the borate a clear solution, The volume and concentration of the acid is designed to polymerise the silica as the melt dissolves. When dissolution of the melt is just complete, polymerisation has proceeded sufficiently for a gel to start to form, as a first stage in the gravimetric determination of silica.The technique is applied in this manner wherever more than 20% of silica is present, All three fluxes are designed to fuse these particularly difficult samples; the resultant melt contains a large excess of carbonate, which ensures a rapid dissolution of the sample. With silica, quinoline molybdosilicate, which is used for the gravimetric determination of that element, has a large favourable factor, so that only a small amount of sample is required, fused with a large excess of carbonate, thus ensuring a rapid dissolution and hence a stable solution.In Table I1 fluxes for chrome bearing materials are also shown. Unpolymerised silica in solution is required for the production of the complex.Instrumental Methods For solution techniques applied to instrumental analysis the requirements are total decom- position by the flux followed by rapid dissolution of the melt. If the silica is precipitated or polymerised, then erroneous results for the silica determinations may be achieved. Other oxides, such as titanium(1V) and zirconium oxides, cause problems in this way. An excess of carbonate aids rapid dissolution, and if by quenching the dish the melt can be freed from the dish twice the surface area is available for acid dissolution.For full analysis (less silica) hydrofluoric acid decomposition followed by fusion of the residue in a lithium borate flux is applied. The use of lithium ensures that potassium and sodium can be determined.An early attempt at devising a flux for magnesite (1 g of sample plus 7 g of fusion mixture plus 8 g of boric acid) led to one which allowed a rapid fusion, but slow dissolution and unstable solutions could be produced. The final method was to fuse 0.25g of magnesite in 1.5g of sodium carbonate and 1.2 g of sodium tetraborate, i e . , reduction of the scale of decomposition, giving rapid fusion and rapid dissolution.A rapid dissolution requirement existed for the flux chosen for chrome bearing materials (0.5 g of sample, 7 g of fusion mixture and 2.5 g of boric acid). Requirements for a flux here are : a glass that does not devitrify on cooling; a clear melt; a bead that does not crack; minimum dilution of the sample in the flux; preferably a low melting-point flux to ensure rapid mixing of the sample to form a homogeneous melt ; and a more comfortable process for the analyst.In order to achieve the first three requirements, it is necessary to consider the nature of the sample. If the material is basic an acidic flux, such as lithium tetraborate, is used; if it is acid a basic flux, lithium metaborate, is required. If the sample contains oxides that do not form good glasses a higher dilution and a good glass-making oxide are needed.Boron(II1) oxide serves this last purpose and hence a higher dilution in lithium tetraborate will work in this instance. Because of the acidic nature of silica and lithium tetraborate, the former fuses only slowly in the latter. Although alumina will fuse in lithium metaborate, the melt produced devitrifies because both flux and sample are more basic; however, the phase diagram shows that there is a low melting-point eutectic a t a composition of one part of tetra- to four of metaborate.This is sufficiently basic to fuse silica readily and acidic enough for alumina not to devitrify. Hence, it is possible to fuse the complete range of silica - alumina materials in a low-melting flux, which is completely fluid even on a gas burner, Note the use of lithium fluxes in Table 111, rather than sodium or potassium fluxes.This is because both soda and potash can be determined by XRF. Zirconium, magnesium and titaniuni(1V) oxides are poor glass-making elements, and need high dilutions in lithium tetraborate. However, if they occur as silicates, i.e., zircon, talc and titanium silicate, there is sufficient of the good glass-making element, silica, that they will fuse at a ratio of 1 : 5 in the mixed flux.It may be noted that limestones can be fused in a 1 : 3 ratio in lithium tetraborate. An ignited sample is fused so that the effective ratio of the dried sample is 2 : 3. If we are looking at low levels of impurity in calcite then a 1 : 3 fusion is ideal.In nature limestones can vary in composition and approach the composition of dolo- mites. Therefore a 1 : 5 dilution would be needed to include both. If magnesites are being For X-ray fluorescence analysis a fused cast bead is used. All four points are illustrated by the examples in Table 111.154 LASERS AND THEIR ANALYTICAL APPLICATIONS Proc.AnaZyt. Div. Chenz. SOC. TABLE 111 FLUXES FOR X-RAY FLUORESCENCE Parts of flux t o 1 part of sample r -7 2- Material T.i,B,O, LiBO, High silicas . . . . . . . . .. 1 High aluminas . . . . . . . . . . 1 Silica - alumina range . . . . . . . . 1 Steatite (talc) . . . . . . . . . . 1 Magnesite . . . . . . . . . . 10 Bone china . . . . . . . . . . 1 Bone ash (apatite) . .. . . . f . 5 Zircon . . . . . . . . . . . . z Zirconium oxide . . . . . . . . . . 12 Titanium(1V) oxide . . . . . . . . 12 Calcium silicate . . . . . . . . . . 1 Limes tone . _ . . . . . . . . 3 Dolomite . . . . . . .. . . . . 5 Iron(ll1) oxide . . . . . . .. . . 12 Chrome-bearing refractory . . . . . . 12.5 Silicon carbide . . . . . . . . . . 1.5 Boron carbide . , . . .. . . . . 0.88 4 4 4 4 0 4 0 4 0 0 4 0 0 0 10 6 3 62 analysed as well it is advantageous to fuse them all in the same way, at the I : 10 sample to flux ratio required for magnesites. Conclusion It is hoped, by the examples given, that the philosophy at BCeramRA for tailoring fluxes to fit the whole analysis scheme has been demonstrated and here is a summary of some of the points made. If a flux is necessary, use as little as possible, i.e., try a sinter. For the gravimetric determination of silica, design the flux and acid mixture so that the silica will dehydrate after dissolution of the melt. For instrumental solution methods use excess of carbonate in order to allow rapid dissolution of the melt. For X-ray fluorescence produce a good glass bead by considering the acidity and basicity of flux and sample having due regard to any poor glass-making elements present in the sample. For trace analysis avoid a flux if possible. The author thanks the Director of Research, Dr. D. W. F. James, for permission to present the paper and acknowledges the help of Mr. H. Bennett in preparing it.

ISSN:0306-1396    

DOI:10.1039/AD979160149b

出版商:RSC    

年代:1979

数据来源: RSC

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154 LASERS AND THEIR ANALYTICAL APPLICATIONS Proc. AnaZyt. Div. Chenz. SOC. Lasers and Their Analytical Applications The following is a summary of one of the papers presented at the Analytical Division Syrn- posiurn held at the Chemical Society Autumn Meeting on September 19th-21st, 1978, at the University of Warwick. Summaries of five other papers presented at the meeting appeared in the March issue of Proceedings (p.97). Development of a Laser-based Instrument System for Monitoring the Concentration and Characteristics of Solids in Suspension N. G. Stanley-Wood, G. J. Llewellyn and A. Taylor University BD7 1DP of Bradford, Postgraduate School 0 f Studies in Powder Teclznology , Bradford, West Y o rk s h i TC , With the increasing use of automatic control systems in the powder process industry a need has arisen for on-stream or real-time instumentation in order to measure the size and solid con- centration of particles in slurries.Particle characterisation parameters can then be fed back for both process control systems and quality control. Incorporation of either auto- orLasers Hybrid photo- L r A.C. coupled R,,(T) = +J x ( ~ - T ) x(t)dt 0 J where x ( t ) is the input signal and T is the delay time.x ( t ) . The cross-correlation function is Hence x(~-T) is a delayed version of T , A R x y ( ~ ) = '1 x ( ~ - T ) y(t)dt T 0 Detection sub-system __ _ _ ~~ - _____ _ _ where y ( t ) is an input signal and x ( ~ - T ) is a different and delayed input signal. The spectrum display evaluates the power spectral density of the incoming signal by Fourier transformation of the auto-correlation function.The nzodus operandi of this new instrument is the measurement of the mean velocity of particles passing between the two laser beams by cross-correlating the upstream and down- stream photo-detector signals. Essentially, this is a sophisticated version of a tagging process to give a fast and accurate measurement of velocity. Particle size can be determined by the measurement of the signal band width obtained from the power spectral density.The relationship between size and velocity can be expressed as ,, Random electrical signal 1 Particle size Band width K A A Spectrum Hewlett-Packard x-Y plotter display w T correlator 1 -156 USE OF THE MICROSCOPE Proc. Analyt.Div. Chew. SOC. and Band width cc Velocity This is, in effect, a transit time method of determining particle size and once the mean velocity of the particle has been obtained the size of particle can be determined. The concentration of flowing and suspended solids passing between the parallel laser beams can be obtained from the auto-correlation function at zero time delay [R,,(O)].However, R,,(O) is also dependent on size, and therefore the size of particle must be known before the slurry concentration can be determined. The quantity being measured is the mean squared value of the signal rep- resenting scattered light. The conditions under which the above laser system operated were velocities between 0.5 and 3.0 m s-l at concentrations in the range 1 x lo-* to 10% m/m for a sand and water slurry and particle sizes of 268-393, 452-572, 600-1 000 pm.The most critical operation performed by the above system is the measurement of particle size because concentration measurement is dependent upon the size of particle being known. However, in order to evaluate a particle’s size its velocity must be determined. This is achieved to a high degree of accuracy by the cross-correlation method, which is independent of both size and concentration. Therefore, further experimental work is being undertaken with particles of closely controlled size distribution within the range 100-1 000 pni. The total system performance can then be examined and accuracy, resolution and repeatability deter- mined.

ISSN:0306-1396    

DOI:10.1039/AD9791600154

出版商:RSC    

年代:1979

数据来源: RSC

摘要:

156 USE OF THE MICROSCOPE Proc. Analyt. Div. Chew. SOC. Use of the Microscope The following are summaries of three of the papers presented at a meeting of the Joint Pharma- ceutical Analysis Group held on November 30th, 1978, at the Pharmaceutical Society of Great Britain, London. Quality Control of Finished Products Jean Prentice McCrone Research Institute, 2 McCrone Mews, Belsize Lane, London.N W3 5BG Product quality control relies on the checking of certain characteristic parameters. The basic requirements for effective control by microscopy are : each property should be measurable with precision ; the properties should be easily and quickly determinable without extraordinary background training; the determinants should be numerically expressible; and the charac- teristics chosen should form a unique set for that particular compound.The polarising light microscope can be used successfully to identify many parameters, such as refractive index, birefringence and morphology. If a hot stage is used, further charac- teristics can be obtained. The behaviour of compounds can be noted during heating or cooling by using the polarising microscope and properties, such as melting-point, sublimation temperature, the presence of solvent adducts, polymorphic modifications, the refractive index of the melt, purity and eutectic melting-points can be measured.Some of these properties are observable macroscopically, but many tests are required to determine the different properties that form a unique set to characterise one compound.Hot-stage microscopy gives informa- tion on many parameters using one analytical instrument. Any deviations from specification, such as excessive impurities or a change of polymorphic form, can be rapidly observed. Some knowledge of microscopy is naturally needed to set up a quality control programme that relies on the hot-stage microscope. Melting-point The melting-point accepted by microscopists is the equilibrium point, which is the tempera- This allows for a consistency between Organic ture at which the solid and melt are in equilibrium.microscopists’ results, which is not generally achieved by macro-scale methods..May, 1979 USE OF THE MICROSCOPE 157 compounds tend to melt over a narrow temperature range of 1-2 O C , because areas of crystal dislocations tend to melt first. When small amounts of impurities are present this range is extended, and the melting-point becomes sluggish.Large amounts of extraneous materials lower the melting-point because of eutectic meltings. Successive melting-point determinations on the same material are required before the pure melting-point can be used for quality control, as decomposition products lower the melting temperature. If product oxidation is affecting the melting-point, the substance can be mounted in silicone gel in order to exclude air.The melting-point of volatile substances can be determined by commencing heating just before the actual melting, or by sealing the substances under a cover slip, to prevent escape. Sublimation temperatures can vary considerably, depending on the heating rate, so that a rigid method of determination must be applied if this is to be used as an identification characteristic.Eutectic melting-points also provide very characteristic data and many organic materials can be characterised by measuring their pure melting-point, plus the melting-points obtained by individual mixing with two standard substances.l12 Some substances start to decompose at their melting-point.Solvent Adducts and Polymorphism If the solvent escapes during heating, it is often visually observable (e.g., the blackening of oxalic acid at 90-100 “C), or the substance can be heated in silicone gel, so that solvent bubbling can be noted. It is also possible with some substances (e.g., codeine) to observe solvent-free crystals growing in the adduct melt when the melting is inhomogeneous.Some products melt only as the adduct (e.g., penicillin) and the use of silicone gel can provide stable condj tions for determining this melting. Polymorphism is, of course, exceedingly important to the pharmaceutical industry, because a considerable proportion of pharmaceuti- cal products are not marketed in their most stable form.The use of hot-stage methods has been well doc~mented.~-~ Different polymorphs have different stabilities, melting-points, crystal forms and efficiencies. Observations of polymorphism can readily be made by using the hot-stage microscope. Different polymorphs are most easily characterised using hot-stage microscopy, by crystallisation from the melt or from solvents.Crystal films produced from melts eliminate the possibility of adducts and provide the best approach to categorising polymorphs. Phase diagrams, addition compounds and eutectic melting-points can be studied by use of hot-stage microscopy, and after a full microscopical study, using polarised light and hot-stage microscopy, it is possible to extract sufficient numerical data in order to form the basis for efficient quality control of pharmaceutical products.Solvent adducts are easier to detect microscopically than by any other method. References 1 . Kofler, Id., and Kofler, X., “Thermo-Mikro-Methoden zur Kennzeichnung Organischer Stoffe und 2 . Kuhnert-Brandstatter, M., “Thermomicroscopy in thc Analysis of Pharmaceuticals,” Pergamon 3.4. 5. Stoffgemische,” Wagner, Innsbruck, 1954. Press, Oxford, 1971. McCrone, W. C., “Fusion Methods in Chemical Microscopy,” Interscience, New Yorlc, 1957. Grabar, D. G., Hession, J . P., and Rauch, F. C., Microscope, 1970, 18, 241. McCrone, W. C., Microscope, 1970, 18, 257. Quality Control of Plastics Films Using Light Microscopy D. A. Hemsley Institute of Polymer Technology, University of Technology, Lotighbovough, Leicestershive, LEI 1 31'U Packaging films represent one of the most spectacular growth areas in the plastics field.However, the number of different plastics used in film manufacture is perhaps less than might be imagined, bearing in mind the wide range of applications. Polyethylene, polypropylene and poly(ethy1ene terephthalate) films make up the bulk, and it is to films from these plastics15s USE OF THE MICROSCOPE Proc.Analyt. Div. Chem. SOC. that these comments on film quality control apply. To cover a range of applications films are specially tailored by varying their manufacturing processes or the additives that are incor- porated into them. Some of these additives are intended to improve the resistance of the film to its in-service environment.Stabilisers are added to inhibit degradation of the film in use or during pro- cessing. Other additives, such as waxes, silicas or clay, are added to improve the handling characteristics of film during processing and to impart the desired end properties. The distribution and dispersion of additives are therefore most important to these properties and a major task of film microscopy is to identify, locate and assess the distribution of additives.Films as Microscopical Objects Films are, in many ways, ideal objects for light microscopy. The vast majority are thin and transparent enough for direct examination of their internal structure or texture. Also, the surfaces of most films are reasonably smooth, so that depth of field problems are rarely encountered. This, combined with the fact that many practical problems are related to structure larger than about 0.5 pm, means that light microscopy is widely applicable, both in transmitted and reflected light modes.In using the transmitted light microscope one must be aware that most films are optically anisotropic, i.e., refractive index is a function of the direction of propagation of light in the film.The degree of anisotropy is related to the polymerisation and manufacturing process used. We assess the optical anisotropy in terms of birefringence, which is the numerical difference between the principal refractive indices displayed. In practice, birefringence in the plane of the film is most frequently considered as observations are readily made in this plane.Microscopical Observation on Quality The quality control of the film may be based on internal or surface microscopical observa- tions. These can include : the measurement of birefringence using a polarising microscope ; the assessment of contamination levels ; the distribution and dispersion of the additives such as slip or anti-blocking aids and pigments; and surface checks on the general roughness of film resulting from the manufacturing process and additives.Birefringence Measurements on Film The magnitude of the birefringence of drawn film and the directions of the principal axes in the plane of the film can be used to monitor the production process, not only because birefringence is a sensitive measure of molecular orientation, but also because it can, at least in a general way, be related to product properties.I t should be stressed that we cannot fully characterise a film by this single in-the-plane measurement and also that what is being assessed may be some combination of effects from crystalline and non-crystalline regions. Nevertheless, such measurements are useful as a process monitoring aid, at least as a guide to consistency of output and to likely in-service properties.In order to carry out the in-the-plane birefringence measurement we require only a simple polarising microscope equipped with a low-power objective, a compensator slot and a rotating stage. The extinction direction for the film relative to the edge of the film is first recorded, then the film’s rztardation (R) is assessed in the usual way, using a Michel Levy colour chart or, better, a compensator.Film thickness (t) can be measured with a dial gauge to sufficient accuracy for the birefringence to be calculated from An = Rit. I t is also necessary, using an accessory retardation plate, to establish the direction of the higher principal refractive index. This procedure is well covered in the literature.Contamination Studies heat-sealing) or in adulteration of the packaged product. techniques may be called into play to locate and identify contamination. Contamination in or on film can lead to a variety of problems in terms of processing (such as The full spread of microscopicalMay, 1979 USE OF THE MICROSCOPE 159 Particulate Additives If the analyst is examining film in the polarising microscope it is worth extending the study to look at the distribution of particulate additives and any modification of the film bire- fringence around them.Large particles of additives in drawn film can give rise to small sur- rounding voids. The shape and dimensions of these voids relative to particle shape provide additional clues to the way in which the film has been manufactured.Surface Studies The nature of a film surface has a profound effect on its transparency and frictional proper- ties. A perfectly smooth film surface might seem to be desirable for applications requiring high transparency, but such surfaces may lead to film layers sticking together so as to make the unwinding of a reel difficult or even impossible! A rougher surface, produced either by the incorporation of particulate additives or by modifying the film production conditions, might give a film with good frictional characteristics but transparency is sacrificed.,4 critical compromise is therefore necessary, requiring close control of surface roughness. Microscopy is a ready method of achieving this control.Fig. 1. The surface of a polypropylene film. Fig. 1 shows the surface of a polypropylene packaging film. The technique used was to shadow it with aluminium, then immerse the film, held between a slide and a cover slip, in a liquid closely matching its refractive indices, as shown in Fig. 2. When examined in the transmitted light microscope this preparation has a shadowed appearance and the shadow lengths can be used to measure the height of surface structures..- Evaporated metal -Film ~ Coverslip I mmersior: liquid - -Slide - Fig. 2 . Method of mounting film specimens lor surface examination using transmitted light micro- scopy. The shadowing technique is time consuming. Specimen preparation is made simpler and quicker if reflected, rather than transmitted, light microscopy is used.However, the contrast can be improved by sputter coating with metal and sensitivity to surface undulations is160 USE OF THE MICROSCOPE Proc. Analyt. Div. Chem. SOC. greatly improved by the use of the Nomarski differential interference contrast method. For the close examination of film surfaces a “contour map” of the surface topography can be obtained by using double or multiple beam microinterferometry. Microscopy of Contaminants of Pharmaceuticals and their Character isat ion M.F. Godfray Public Analysts Department, Municipal O$ces, Larcorn Street, Walworth Road, London, SE17 1 R Y The type of contaminant that I am going to consider is the solid, particulate contaminant, derived from various sources and manifesting itself in the final pharmaceutical product or an intermediate. Furthermore, as we are concerned with light microscopy, these particulates will be, at least in part, greater than 1-2 pm in size.Obviously what is needed is to establish the nature of the contaminant and, ideally, its source. In order to characterise and identify small particles the analyst will probably need the correct equip- ment, experience, expertise and (perhaps the most essential prerequisite) a measure of self- confidence.The most essential part of his equipment is, in my opinion, a collection of standard materials for microscopy, because a great many of his identifications will be based on the comparison of the unknown particles with these standards. The sort of materials needed in such a collection form an almost endless list, viz., local soils, gaskets from the processing plant, packaging materials, a collection of the company’s products and intermediates, pollen samples from local flowering plants or, in other words, everything and anything.Gaskets and similar materials may need subjecting to a treatment similar to the production process, which might alter their character and may even extract or form the particular contaminant itself. When characterising a particle, the first thing to note is the morphology of the particle.The word note means a written note, in this instance, as detailed, written notes are essential for serious microscopy; never rely on memory alone. The morphological features to note are as follows. Size.SJzape. Surface characteristics. The surface might be smooth, cratered, porous, etc., and some form of incident (top) illumination may be needed for observing such features, as well as the normal transmitted illumination. Unfortunately, there is no easy means of identifying such contaminants. Always have a calibrated graticule in the microscope eyepiece for this purpose. Drawing a diagram of this may help; photography may be better.Crystalline form. Homogeneity. Hardness or texture. Colour. Transparency. An important point about morphology is to ensure that there is a standardised nomenclature to describe the various characteristics, particularly if several personnel are to be engaged in the work. For example, I have used the terms cratered and porous, which are each distinct features but which can be confused when describing a surface.I t might be possible to produce a photographic atlas to illustrate this standardised nomenclature. Other features that might aid in the characterisation of particles are the physical properties and the chemical properties that can be established. This should be noted, if appropriate. This feature, or the lack of it, should be noted.Press the sample with a cover slip or probe with a fine needle. This is preferably observed by both transmitted and incident illumination. This feature, or the lack of it, should also be noted. Physical Properties only an estimate of the figure is required. experiment with. application because it may be a destructive technique. Density. Solubility.Behazriour on heating. This is difficult to determine with small particles, but not impossible, especially if This is of limited application, particularly if there are very few particles to This is best carried out on a hot stage and again is of possibly limited.Way, 1979 USE OF THE MICROSCOPE 161 If the particle is transparent, then the refractive index (or refractive indices, if more than one) can be determined, together with the presence or absence of birefringence.It may be possible actually to determine a numerical value for the birefringence, but this is more usually carried out for fibres rather than particles. Again, with transparent particles, the behaviour exhibited with a dispersion staining objective and standard refractive index fluids can give valuable information about the material; it is possible, with this same equipment, to plot dispersion staining curves to characterise transparent materials.For many crystalline, transparent materials it is possible to observe what are termed interference figures, and very experienced microscopists and crystallographers can identify many materials purely by observation and assessment of such figures.Chemical Properties I suppose that one could consider the behaviour on heating as being a chemical property, under certain circumstances, but what I am mainly concerned with here are microchemical tests. I am not necessarily recommending that a complete qualitative analysis on a single 100- or 1000-pm particle be attempted, but if the analyst has an idea what the particle is, and needs a confirmatory test, then a microchemical test might be suitable.For solving any problem, the correct equipment is, of course, highly desirable, if not essen- I have already mentioned the collection of standard materials, some of which, incident- The tial. ally, might require grinding down to a suitable size for microscopical examination. other desirable equipment is as follows.Steveo-zoom binocular microscope, x 5 to x 150 power. Particle handling equifimeizt. This includes tweezers, glass rods, capillary tubes, tungsten PoZarised light microsco$e. This instrument should possess incident and transmitted illumina- Dispersion staining objective. A hot stage and phase-contrast equipment may be desirable for particular applications. The former is particularly useful when a number of the particulate contaminants encountered are organic in nature, and the application of controlled heating may give useful information.The latter allows more accurate assessment of the refractive index of a transparent contami- nant, which might be essential for its characterisation. The analyst should ensure that the stereo microscope that he will use will give sufficient magnification for handling small particles.The use of supplementary lenses might reduce the working distance but this may often be considered worthwhile when the particles are very small and very finely pointed needles are being used for handling. A polarised light microscope will be far better for particle identification purposes than a biological microscope equipped with a simple polariser and analyser.Such a polarised light microscope would have a rotating stage and compensator plates, which together would assist with the assessment of birefringent materials. A major problem with microscopy, perhaps more so than with most other analytical tech- niques, is the difficulty of obtaining adequate training in the technique. Several establish- ments run short, intensive courses in microscopy: The Polytechnic of the South Bank, Leeds University, McCrone Research Institute, Royal Microscopical Society, etc. However, microscopy generally involves many years of practice before a true expertise develops, even with the aid of such courses. There are many text-books available on microscopical tech- niques. The most useful, in my experience, for the techniques involved in the identification of particulate contaminants are those listed in the Bibliography. wire, etc. tion capabilities. Bibliography McCrone, W. C., and Delly, J . G., “The Particle Atlas,” Volumes 1-6, Ann Arbor Science Publishers, Ann McCrone, W. C., et al., “The Particle Analyst,” Ann Arbor Science Publishers, Ann Arbor, Mich., 1968. Bendetti-Pichler, A. A., “Identification of Materials via Physical Properties, Chemical Tests and Micro- Chamot, E. M., and Mason, C. W., “Handbook of Chemical Microscopy,” Volumes 1 and 2, John Wiley, Arbor, Mich., 1973 to 1978. scopy,” Academic Press, New York, 1964. New York, 1958.

ISSN:0306-1396    

DOI:10.1039/AD9791600156

出版商:RSC    

年代:1979

数据来源: RSC

摘要:

162 EQUIPMENT NEWS PYOC. Annlyt. Div. Chena. SOC. Equipment News High- performance Liquid Chromatograms The LC-XP Series, a new range of higli-perform- ance liquid chromatography instruments, columns and accessories, has been launched. Both isocratic and gradient elution liquid chromatographs are available, based on the dual-piston reciprocating punip. known as the LC-SPD. Other system modules include the LC-XI’ Gradient Programmer, which is able to store up to ten complete programmes in non- volatile memory, the LC-FL fluorinietric detec- tor, which makes possible the high sensitivity selective detection of fluorescing compounds, and the LC-UV, a variable-wavelength ultra- violet detector, having an absorbance range of 0.005, new coated optics and a switchable activc filter.An extended selection of packed columns and acccssories is also available. I’ye Unicam Ltd., York Street, Cambridge, CBl 2PX. Liquid Chromatographs A line of modular liquid chromatographs has been announced. The modules include the 950 pump, which covers a pressure range from ambient to 10 000 lb inr2 a t flow-rates from 0 01 to 40.0 nil min-l by the use of two inter- changeable pump heads, arid the 965 photo- conductivity detector, which provides specific detection of halogenated samples through con- ductivity measurements.Techmation Ltd., 58 Edgware Way, Edgware, Middlesex, HA8 8 J P. Liquid Chromatograph A liquid chromatograph for accurate determina- tions of extremely low concentrations has been developed, the Model 931. With this instru- ment, for example, sugar fractions can be detected down to hundredths of 1 p g inl-I.The high sensitivity refractive index liquid chromatograph Model 93 1 can also be used with other types of detectors, such as ultraviolet, fluorescence and electron capture. Optilab Instrumentation AB, Box 135, S-162 12 Vallingby, Sweden. Valves for High-pressure Liquid Chroma- tography Both pneumatically operated and electrically operated high pressure liquid chromatography valves arc now available, incorporating the Scientific Systems Inc.range of remote actu- ators. Scientific Glass Engineering, 657 North Circular Road, London, NW2 7AY. Regulator The Porter Model 8286 precision regulator can now be supplied with a stainless-steel diaphragm, which could overcome problems associated with the use of rubber diaphragms with capillary columns in gas chromatography.Scientific Glass Engineering, 637 Korth Circular Koad, London, NW2 7-4Y. Chromatogram Columns Kits are available to enable chromatograph columns to be assembled in unit lengths of 30 cni in both 16- and 26-min diameter. Flow adaptors and end-pieces, a three-way valve and sample syringe are included in the kit.A solvent reservoir kit including a column packing device is also available. LKB Instrunicnts Lttl., 232 Addington Road, South Croydon, Surrey, CZ<2 8Y D. Preparative Chromatogram l<ecently announced is the Jobin-Uvon Miniprep LC preparative HPLC instrument to coniple- nient the existing Cliromatospac range, based on a stainless-steel column, 500 nim by 20 mm diameter.Axial compression of the packing results in a column with upwards of 35 000 theoretical plates per metre. The amount of packing material required can be varied from 5 to 50g depending on the separation to be performed. The Miniprep incorporates two reservoir pumps, which are pressure operated and which can be operated to give a “step-gradient” elution. Sample injection can be via syringe or sample reservoir and sample sizes from 1 pg to 1 g can be accommodated.E D T Research, 14 Trading Estate Road, London, NWl0 7LU. Gas Chromatograph A gas chromatograph for headspace analysis that can operate a t temperatures up to 150 OC, the Model F45, incorporates an integral thermo- stat in place of the water-bath of the earlier Models F40 and F42.With column effluent splitting, dual detector combinations of FID, ECD or NPD can be used. The electro-pneumatic sampling system ensures high reproducibility and prevents sample carryover. Up to 30 samples can be acconimodated on the sample turntable and processed automatic- ally. A column backflush accessory can be used to remove high-boiling components with long retention times.May, 1979 EQUIPMENT NEWS 163 Perkin-Elmer Ltd., Post Office Lane, Beacons- field, Buckinghamshire, HP9 1QA.Interface Connecting System A new interface system for connecting a gas chromatograph to a mass spectrometer consists of an all-glass jet separator with the necessary isolation and control valves mounted in a com- pact stainless-steel oven. Provision is niadc for direct capillary column connection or packed column connection via the separator with facilities for solvent dumping.Scientific Glass Engineering, 657 Xorth Circular Road, London, NW2 7AY. Computer for Infrared Spectrometry The Infrared Data Station, a desk-top computer, can be connected directly to most of Perkin- Elmer’s high-performance infrarcd instruments. 7’hc simple operation and low cost of the Infra- red Data Station is designed to make i t suitable for routine use.The Data Station consists of a processing module with integral, dual, micro-scale, floppy disc drive unit, an alphanumeric keyboard and a visual display unit. When used with the hIodel 580H, the Ilata Station provides com- plete instrument control for automated opera- t ion. Perkin-Elmer, Post Office Lane, Beaconsfield, Buckinghamshire, HP9 1QA.Data System X data system h a s been added to the SP2000 and SP4000 infrared spectrophotonieters using a “conversational” Hewlett-Packard desk-top calculator. Communication between the spec- trophotometer and the calculator is provided b y the SP2080 Data Conversion Unit. Litera- ture is being published giving further details of the system and its capabilities.Pye Unicam Ltd., Yorlc Street, Cambridge, CB12PX. Scanning Electron Microscopes The high-performance IS1 l O O X has a G-nni guaranteed resolution ( 5 nm attainable), 10 x to GOO 000 x magnification, 1-40 kV accelerating voltage in l-lcV steps (50 kV option) and dual magnification on two 12-in screens. The stage provides complete coverage O E a 4 in diameter specimen. The IS1 GOA has a 6-nm guaranteed resolution, 10 x to GOO 000 Y magnification and 1-30 kV in l-kV steps.I t offers split-scrocn dual magnification on an extra-large screen, and givcs full coverage of 4-in diameter x 3-in deep specimens. The IS1 40 has n guaranteed resolution of 6 nm with 1Ox to GOO OOOx magnification and 1-39 kV in l-kV steps. I t also offers split-screen dual magnification on an extra-large screen, and gives full coverage of 4-in diameter x 3-in deep specimens.The Super IIIA offers 7-nm guaranteed resolution, magnification of 10 x to 1GO 000 x , 2-30 kV and a 3-in stage. The smallest of the range is the Alpha 9, a 13-nm, 15-kV unit, with a magnification of 30 x to 80 000 x and an automatic micron bar. International Scientific Instruments Inc.(UK), Waterwitch House, Exeter Road, Sew- market, Su ff olk. Fluorescence Detection Micro Flow Cells A new rectangular liquid chromatography micro flow cell for fluorescence detection offers a signal tr, noise ratio 4.5 times better than that obtained with cylindrical cells. Models have been introduced for use with the line of M P F instruments and with the Model 204 fluorescence spcctrophotorncter. Measured signal to noise ratios of the new 20-pl cell approach values obtained with standard 3-1121 cells.Perkin-Elmer Ltd., Post Office Lane, Bcacons- field, Buckinghamshire, HPD IQA. Calibration Source An accurate Model 420 calibration source is available, consisting of an 8-in diameter integrating sphere and a 45-11 tungsten - halo- gen lamp.The lamp is mounted on a moveable platform and an aperture wheel containing five difference apertures is mounted in front of the integrating sphere, to vary the output from the source continuously. The standard source is calibrated over the range of 350-1 200 nm. Calibrations for the range 250-350 and 1200-2500nm are also available. Glen Creston Instruments Ltd., 16 Carlisle Road, London, NW9 OHL.Data Processing Recorder The Bryans BS8000, a inulti-channel recorder with data processing and storage facilities, is announced. The BS8000 can digitise, record and process up to eight channels of analogue data, with raw or processed data plotted in real time on the X - Y plotter or stored on a flexible disc. Each disc is equivalent to 100 yards of chart paper, with any sequence of data retriev- able in graphical form in a few seconds.Simple keyed commands control the instrument or allow data to be processed before plotting. Bryans Southern Instruments Ltd., Willow Lane, Mitcham, Surrey, CR4 4UL.164 EQUIPMENT NEWS Proc. Analyt. Div. Chem. SOC. Disposable Pens for Chart Recorders The range of eight disposable pens including box and cylindrical pens for use with the Bryans 28000 Series and X - Y plotter recorders is announced, to bring fibre-tip pen benefits to users of Bryans instruments and overcome problems associated with capillary inking systems.Graphic Controls Ltd., P.O. Box 774, Clyde Vale, Forest Hill, London, S.E. 23. Micro-sampler for Atomic Absorption The Model AS-3 autosampler for micro-sample injection with flame atomic-absorption spectro- scopy is now available.The model automati- cally injects 50- or 100-pl samples directly into the instrument nebuliser. The AS-3 is compatible with all Perkin-Elmer atomic-absorption instruments, and allows the pre-selection of from one to ten analyses per sample for up to 30 samples. A complete analysis cycle, including a two-step wash, can be carried out in 15 s.Perkin-Elmer Ltd., Post Office Lane, Beacons- field, Buckinghamshire, HP9 1QA. Mercury Hydride System The MHS-10 Mercury Hydride System, an atomic-absorption accessory for the determina- tion of mercury and the hydride-forming ele- ments, is manually operated and offers ease of operation, high sensitivity and good detection limits for Hg, As, Se, Te, Sb, Bi and Sn.The MHS-10 is compatible with all Perkin-Elmer atomic-absorption instruments. Perkin-Elmer Ltd., Post Office Lane, Beaconsfield, Buckinghamshire, HP9 1QA. Focusing Mechanisms A complete line of precision focusing mechan- isms for applications in scientific, engineering and production equipment is now available. The units are available as focusing microscope tubes with magnifications from 4 to 2 O O O x or as focusing supports whereby the top-plates may be adapted to special applications.The assemblies have measuring ranges from 1 to 125 mm with fine-focusing accuracy of 2 pm. Melles Griot B.V., Nieuwe Kade 10, Postbus 567, Amhem, The Netherlands. Off - axis Parabolic Mirrors -4 series of high-precision off -axis parabolic mirrors for use in collimators, laser-beam expanders, spectrophotometers, monochroma- tors and other optical systems such as interfero- meters and astronomical instruments is now offered. With unrestricted access to thc focal point, energy concentrated there can be con- veniently measured and images easily viewed without interfacing with the incoming beam.When used as a collimator the source does not obscure part of the mirror.The mirrors are made of fine annealed Pyrex and have a surface accuracy of 1/20 lambda a t 633 nm, guaranteeing diffraction-limited per- formance. Coated with high-efficiency coating, the reflectance is 94% minimum. Each mirror is supplied in a black anodised aluminium mount. Melles Griot B.V., Nieuwe Kade 10, Postbus 567, Arnhem, The Netherlands.Laser The 25-mW Model 107A helium - neon laser provides high output power for OEM systems. The glass-to-metal seals permit processing of the tube a t very high temperatures for complete removal of moisture and contaminants, to give consistent output power during life. Field tests indicate at least a 20 000-h life. The Spectra-Physics Model 107A laser is available with the Model 207 power supply.Spectra-Physics Ltd., 17 Brick Knoll Park, St. Albans, Hertfordshire, AL1 5UF. Radiometer/Photometer Now offered is the Model 730A Radiometer/ Photometer for accurate measurement of both continuous and pulsed light sources. The wavelength range covered is from 200 to 1100 nm. The sensor consists of a stable, ultraviolet- enhanced silicon yhotodector with an area of 1 cm2 with uniform sensitivity over the entire receiver.Radiometric and photometric filters are provided . Glen Creston Instruments Ltd., 16 Carlisle Road, London, NW9 OHL. Particulate Monitoring A new range of aerosol systems for detecting and monitoring airborne contaminants indoors or out, is announced. The systems comprise Models J M-5000 featuring logarithmic output, JM-6000 with 5-range selectable linear amplifi- cation, and JM-7000, a combination log/linear instrument.Designed for testing and monitor- ing HEPA filters, the photometers include a high sampling rate, 100% solid-state electronics and a choice of 5-decade logarithmic, 5-range linear or combined display. The upper limit of all the JM series photometers is higher than the turbidity of any atmospheric aerosol except dense water fogs, with lower limits that corres- pond to an atmospheric visibility of 930 miles.May, 19 79 EQUIPMENT NEWS 166 'Techmation Ltd., 58 Edgware Way, Edge- ware, Middlesex, HA8 8JP.Balances New PC top-loading balances, incorporating the Delta Range, substantially expand the limits of the capacity/accuracy ratios of conventional balances.The Delta Range is ten times more accurate than the coarse range, covering one tenth of the total weighing range, and has one extra decimal point. When using a PC balance ir? practice, if the weight of the container exceeds the fine range, the tare weight is auto- matically indicated with the readability of the coarse range. Operating the Delta Range now enables weighing to begin at zero with the accuracy of the fine range and continues that way until the limit of the fine range is reached.By connecting in the GC301 application input device, the balance can be used to count small parts, determine mass changes in per cent. and in grams (e.g., moisture content determina- tions), determine running net totals and perform serial weighings to zero (by first entering a negative reference mass).A. Gallenkamp and Co., P.O. Box 290, Technic0 House, Christopher Street, London, EC2P 2ER. Iris Diaphragms A complete selection of precision iris diaphragms, which are widely used as variable apertures in cameras and other optical, opto-mechanical and opto-electronic systems, is now available. The diaphragms have a re-designed leaf profile that allows the use of a larger number of leaves per diaphragm, resulting in a more circular aperture.The new diaphragms withstand in excess of log openings and closings without failure, either through manual or motorised operation. They are factory lubricated and require no service throughout their life, and are available in sizes from 15 to 300 mm. Melles Griot B.V., Nieuwe Kade 10, Postbus 567, Arnhem, The Netherlands.Dissolved Oxygen Meter The Model 9440 dissolved oxygen meter measures dissolved oxygen in parts per million or percentage saturation using a single sensor. The instrument is suitable for mounting in both process control and effluent treatment applica- tions. When combined with a Model 9407 electrode system, the system incorporates self- calibration, to ensure that optimum electrode performance is maintained for long periods of time. Electronic Instruments Ltd., Hanworth Lane, Chertsey, Surrey, KT 16 9LF.Process Titrator The Model 1800 DigiChem process titrator is a fully automated, general-purpose analyser, which can be used to determine any inorganic or organic species and dissolved metals for which titration methods are available.The DigiChem measures the volume of reagent required for the specified end-point on a measured volume of sample, automatically sub- tracts a titration blank, calculates the answer in the specified engineering units and displays or transmits the result on the selected output mode. It can be further programmed to measure two end-points in each cycle and to treat the data arithmetically to obtain the desired results directly.Techmation Ltd., 58 Edgware Way, Edgware, Middlesex, HA8 8 JP. Freeze- dryer A heavy-duty freeze-dryer for research or pilot production has been introduced. The VirTis Freeze-mobile 11, with a total condensate capacity of 18 1, can achieve temperatures of -55 "C in less than 20 min as standard and -85 "C with optional cascade freezing.The condenser has aclear acrylic cover through which the user can observe the ice build-up during drying, and an automatic hot-gas quick defrost allowing the complete removal of the 18-lice-plug in 3 h. Five base models are available. Techmation Ltd., 58 Edgware Way, Edgware, Middlesex, HA8 8JP. Laser Particle Counter The Model 226 laser-illuminated aerosol particle counter and sizing system has been designed to function as a 16-channel, high concentration/ high sensitivity particle counting system.The aerosol particles are counted by collecting the scattered light from each particle over a large solid angle in the sample stream, with an extremely sensitive solid-state photo- detector. The high-sensitivity laser-based optical system is capable of detecting particles as small as 0.1 pm in diameter.Maximum recommended particle concentration is 50 000 000 f V . Gelman Hawksley Ltd., 12 Peter Road, Lancing, West Sussex, BNl5 8TH. Filter Cartridges Three new solvent-resistant micro-filtration cartridge types have been developed for micro- clean filtration of solvents and gases required166 EQUIPMENT NEWS Proc.Analyt. Div. Chem. SOC. by the electronics, chemical, medical and pharmaceutical industries. Each cartridge, containing a large pleated filter surface area, is designed to produce useful fluid flow-rates at low differential pressures. The standard cart- ridge size is 24.9 cm (9.8 in) in length and is available in 0.2-, 1- and 5-pm pore sizes. Each of the three new filter media types is chemically compatible with most aliphatic and aromatic hydrocarbons and solvents.The 0.2-pm pore size cartridges contain 0.2- p m absolute pore size Teflon membrane filter material and resist wetting with aqueous fluids. Solvent cartridges with a 1-pm rating use micro-glass-fibre, and 5- pm cartridges a polypropylene fibre filtration medium. A new series of Acroflow cartridge filters, with extra long-life characteristics, called Acroflow 11 1, incorporate expanded filter area and two-level serial filtration.The 0.45-pm Acroflow 11 1 provides complete particulate matter removal and bacterial rcduc- tion. In filtration of LVP dextrose solutions Acroflow 111 cartridges have five times the life of Acroflow 11. Acroflow 111 is available in pore sizes of 0.45 pm (Product Nos.12680, 12681) for particulate matter removal and bacterial reduction and 0.2 pm (Product Nos. 12682, 12683) for applications requiring finer filtration. Both pore-size variations are avail- able in the single open-end and double open-end variety for installation in competitive housings, or for stacking in high flow-rate applications. Acroflow 11 1 cartridges are sterilisable by ethylene oxide and radiation or can be sanitised by chemically compatible agents.Gelman Hawksley Ltd., 12 Peter Road, Lancing, West Sussex, BN15 8TH. Mixers A series of shaker-mixers is announced, with capacities ranging from 10 to 600 kg. Turbul- ence leading to rapid mixing is due to the three- dimensional motion imparted in a systematically controlled pulsating manner.Glen Creston Ltd., 16 Carlisle Road, London, NLV9 OHL. Bellows Valves Bellows sealed valves with high-temperature, Vespel plastic stem tips are now available. The new valve models provide consistent soft seal shut off a t temperatures from cryogenic to 240 "C. Available in hand and air-operated models, the valves incorporate a flexible metal bellows seal to atmosphere, positive stem re- traction and safety back seat sealing.Pressure ratings are high-vacuum to 2 500 lb in-2 with a 10004 helium leak rate of 4.14 x atm Standard materials are 31 6 stainless steel, Monel and brass with end connections ranging from a- to &-in Swagelok, 6- to l-in butt-weld and 4- and $-in socket-weld. Syndico (Warrington) Ltd., 1G Ltgh Street, Warrington.cm3 s - ~ . Pressure Filter Pressure filtration apparatus with all non- metallic surfaces is designed for field or labora- tory use to separate particulate from dissolved solids in all types of waters. Certified filters of specified metallic ion content can be used to retain the particulate fraction, for subsequent atomic-absorption or other instrumental analy- sis to determine particulate heavy metals.Radionuclides in particulate matter can also be determined. A 0.45-pm membrane filter can separate solids from 500 ml to 6 1 of potable and highly turbid waters in a few minutes. Millipore (U K) Ltd., Millipore House, Abbey Road, London, NWlO 7SP. Laboratory Titrators A range of automatic titrators consisting of Karl Fischer, end-point, pH-stat and recording titrators, incorporating a photo-electric counting device giving precision in dispensing titrant and sample, is announced. Electronic Instruments Ltd., Hanwortli Lane.Chertsey, Surrey, KT 16 9LF. Laboratory Scaffolding The Clinipex 55 range of laboratory scaffoldings includes a large number of clamps and connec- tors for use with tubes of up to 0.55 in diameter, designed to enable almost any structural franie- work to be achieved. Supporting this range is the 25 Series, which is intended for tubes of up to 0.25 in diameter where smaller structures are required.All scaffolding items are sold separ- ately and two kits are also available, one includ- ing a selection of 55 and 25 range fittings, and the other containing a selection of the most popular items from the 55 range.The material is tested to a load strength of 1 ton. Climpex Ltd., Hammers Lane, Mill Hill, London, NW7 41)Y. ,. Regulator 1 he Texcom 44-2200 Series regulators are designed to regulate any gas or liquid, including corrosive media. All media wetted parts are type 316 stainless steel or Du Pont Teflon.May, 19 79 EQUIPMENT NEWS 167 Metal-to-metal sealing of the diaphragm be- tween the body and the bonnet gives further protection from contamination.Models are available for primary pressures of 3 000 and 400 Ib i r 2 with a choice of secondary pressure ranges of 0-25, 0-50 and 0-100 lb in-2. Techmation Ltd., 58 Edgware Way, Edgware, Rliddlescx, HA8 8JP. Literature A series of leaflets on the GasTech range of gas- detecting, measuring and alarm instruments is available.Vertec Scientific, 11 Hag Hill Rise, Taplow, Maidenhead, Berkshire. A brochure entitled “Wilks Miran LC detec- tor,” describing the application of the Miran liquid chromatography infrared detector, is available. An illustrated brochure details thc various uses of the Miran 801 ambient air monitoring system. Wilks Infrared Centre, Foxboro Analytical, P.O.Box 449, South Norwalk, Conn. 06856, USA. A catalogue of the range of portable and installed radiation monitors is available, en- titled “Health Physics Equipment.” h’uclear Enterprises Ltd., Bath Road, Hcen- ham, Reading, RG7 5PR. The May/ June 1978 edition of Intevnationnl Labovatory includes articles on field-flow frac- tionation-single-phase chromatography for macromolecules and particles ; on some applica- tions of GC - MS in the forensic laboratory; and reviews of analytical techniques in isoelectric focusing and of quantitative photometry of thin- layer chromatograms.The September/October edition of Intevnational Labovatovy contains articles on the use of radio- active inert gases as a research tool, and on analysing environmental samples by anodic- stripping voltammetry.International Labovatovy, 16 Argyle Road, London, W13 8AA. A new catalogue details a full product range with accessories and components for chromato- graphy sys terns. Autolab Division, Spectra-Physics Ltd., 17 Brick Knoll Park, St. Albans, Hertfordshire, ALl 5UF. The Ionic 200 series of laboratory monitors for the analysis of natural and waste waters is described in a recent booklet.A catalogue is also available showing the range of liquid and gas chromatography equipment and accessories. Techmation Ltd., 58 Edgware Way, Edgware, Rliddlesex, HA8 8 JP. The Water Research Centre is publishing work on the discharge of sewage to the sea as a series of Technical Reports. TR 67 covers Indicators of Pollution and TR 68 covers Site Investiga- tions.Other publications available are TR 65, reporting the results of the WRC standard analytical samples scheme on the accuracy of inter-laboratory analyses, and TR 66, a manual of analytical quality control for the water industry. Water Research Centre, Stevenage Labora- tory, Elder Way, Stevenage, Hertfordshire, SG1 1TH. A new technical booklet on polyacrylamide gel electrophoresis is available from Pharmacia.Pharmacia (Great Britain) Ltd., Prince Regent Road, Hounslow, Midcllesex, TW3 1NE. A catalogue of the up-to-date range of com- pounds labelled with stable isotopes can be obtained from B.O.C. B.O.C. Ltd., Prochem, Deer Park Road, London, SW19 ].YE. Two technical information sheets on the application of thermal analysis to polymers and catalysts are available.Stanton Redcroft, Copper Mill Lane, London, Sty17 OBN. A series of brochures describing the Model 650- 10 fluorescence spectrophotometer, the Model 420 auto-sampler for liquid chromatography, the HS-6 headspace analyser accessory for the Sigma series gas chromatographs, three new microprocessor systems for sorting and pro- cessing data from high-performance fluorescence spectrophotometers (Models MPF-4, 43A and 44A) and the Model R-600 Fourier Transform nuclear magnetic resonance spectrometer are now available.Also available is an applica- tions data bulletin] “Higher Order Derivation Spectrophotometry,” describing, with examples, fourth derivation analysis using ultraviolet - visible spectrophotometry. The latest issue of the infrared accessories catalogue deals in addition with liquid, gas and solid sampling accessories.Also included are developments in MIK accessories of interest for HPLC. Perkin-Elmer Ltd., Post Office Lane, Beaconsfield, Buckinghamshire, HP9 1QA.165 EQUIPMENT NEWS Proc. Analyt. Div. Chem. SOC. Information is available on two analytical systems using a disposable ion-exchange column technique.Firstly, catecholamines, meta- nephrines and dopamine are isolated and sub- sequently measured by trihydroxyindole fluori- metric assay. Secondly, the Urinary dALA test for lead poisoning depends on isolating dALA followed by colorimetric measurement. Bio-Rad Laboratories Ltd., Holywell Indus- trial Estate, Watford, Hertfordshire, WD 1 8RP. Application notes are available on the simul- taneous measurement of moisture and oil con- tent in oil-bearing seeds, and on the direct mea- surem,ent of the solids content of fat blends, both techniques making use of variable gate widths in the Newport C.W.NMR Analyser. A note on the measurement of oil in petroleum wax using the MK IIIA instrument is also available. Newport Instruments Ltd., Newport Pagnell, Buckinghamshire, MK16 9HF.A brochure is available describing sample filtration to the highest standard. Balston Ltd., Springfield Mill, Maidstone, Kent, ME14 2LE. A data sheet can be obtained describing the range of column-end fitting assemblies, to- gether with information on a slurry packing reservoir for working pressures up to 10 000 lb in-2 in high-pressure liquid chromatography. Scientific Glass Engineering (UK) Ltd., 657 North Circular Road, London, NW2 7AY.A new diagnostic and haematology product brochure includes information on the recently developed gamma-GT test and a mini-vial presentation of the CK-NAC test. J. T. Baker Chemicals B.V., P.O. Box 1, 7400AA, Deventer, The Netherlands. A catalogue describing the range of air and water pollution monitoring instrumentation available from a leading manufacturer is obtain- able. Techmation Ltd., 58 Edgware Way, Edgware, Middlesex, HA8 SJP.A comprehensive catalogue, “Single Source of Supply for Marking Systems,” has been made available. Graphic Controls Ltd., P.O. Box 774, Clyde Vale, Forest Hill, London, S.E. 23. -9 brochure entitled “Products for the Analyst” covers the Specpure range of more than 300 high-purity materials available.The Spectro- flux range of analytical fluxes, the Spectromel range of standard powder mixtures and the JMC electrode materials are also included. Johnson Matthey Chemicals, 100 High Street, Southgate, London, N14 6ET. A new application note, AN 288-5 (Pub. No. 5952-5774), describes the HP glass capillary system used in the splitless mode. Hewlett Packard Ltd., King Street Lane, Winnersh, Wokingham, Berkshire, RGll 5AR.The latest Cerac inorganic chemical catalogue is now available. A number of the items in the catalogue are available in small amounts and many of the entries are rare compounds and alloys. Transatlantic Metals Limited, The Fair Field, Lewes Road, East Grinstead, West Sussex, RH19 3ND.New Materials A range of carrier ampholytes named “Pharma- lyte” for isoelectric focusing is announced. A selected grade of Sephadex G-75, known as Sephadex IEF, has also been developed for this use. High-purity protein standards are provided in a ready-to-use lyophilised mixture in two new electrophoresis calibration kits. The HMW kit covers the relative molecular mass range 669000 to 67 000 in polyacrylamide gradient gels and 330 000 to 18 500 in SDS gels. The LMW kit covers the 94 000 to 14 400 range. Pharmacia (Great Britain) Ltd., Prince Regent Road, Hounslow, Middlesex, TW3 1NE. The Milli-Q system produces reagent-grade water of 18MQ resistivity, free of organic, inorganic and particulate contaminants, to enable it to be used in the preparation of stan- dards and for sample make-up in atomic-absorp- tion and othcr elemental analysis, organics determinations with GLC and HPLC and in algal bioassays. Millipore (U.K.) Ltd., Millipore House, Abbey Road, London, NWlO 7SP. A single incubation Quantimune HTSH immunoradiometric assay system involving simultaneous addition of labelled and solid- phase antibodies prevents sandwiches of HTSH and labelled antibody being formed. The Immunobeads remain in suspension, thus maximising the sensitivity of the system. Reagents for the Quantimune T-4 RIA assay are now supplied in liquid form. The performanceiWadv, 1979 ANALYTICAL CHEMISTRY IN UK UNIVERSITIES 169 characteristics and stability of the complete using Immuno-beads as the support, giving system do not differ from the dry format excellent sensitivity and precision. system. Bio-Rad Laboratories Ltd., Caxton Way, The Quantimune Digoxin RIA test system is Holywell Industrial Estate, Watford, Hertford- now based on the solid-state support technique shire, WD1 8RP.

ISSN:0306-1396    

DOI:10.1039/AD9791600162

出版商:RSC    

年代:1979

数据来源: RSC

摘要:

ANALYTICAL CHEMISTRY IN UK UNIVERSITIES 169 Analytical Chemistry in UK Universities, Polytechnics and Colleges This article is the second in a series that will describe current activities in analytical chem- istry departments and sections in UK Uni- versities, Polytechnics 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 will be published at intervals ; however, con- tributions from any departments with an interest 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 in the University of Wales Institute of Science and Technology, Cardiff The decision of the Welsh College of Advanced Technology, in 1961, t o appoint a Senior Lecturer “to be responsible for all instruction in inorganic and analytical chemistry” with the added requirement “to play a prominent part in developing new courses and research” heralded the way for analytical chemistry per se to have an important place in teaching and research a t what was later to become The University of Wales Institute of Science and Technology (U\VIST).The appointment was given to J. D. R. ‘Thomas. Having held lecturing appointments to degree level in various colleges, albeit in inorganic and physical chemistry, Thomas had already applied to his teaching and research the interest in analytical chemistry obtained by earlier experience in industry and in a public analyst’s laboratory. Also, in 1958 he had devised and planned one of the first “Advanced Analytical Chemistry” courses to exist as an endorsement to the Higher Xational Certificate in Chemistry, which was run a t the South East Essex Technical College (now part of the North East London Polytechnic).Undergraduate Analytical Chemistry There could not have been a more apt moment for an appointment.The planning stage of a 4-year sandwich course for the Diploma in Technology, later to become the BSc(Tech) (Wales) degree in Industrial Chemis- try, soon to be under way, meant that it was possible to start afresh. In this course, analytical chemistry was to have a prominent place alongside the more traditional inorganic, organic and physical chemistry and be supported by the basics of chemical plant and industry (chemical technology), polymer chemistry, mathematics, statistics, computing, physics, communication, economics, business adminis- tration and accountancy.Analytical chemistry is equally well placed in certain other degree courses a t UWIST, where chemistry stands alongside polymer chemistry and technology and environmental science.The result is that all undergraduates in the Chemistry Department, housed in the Redwood Building in Cathays Park, follow lecture courses of about 40 hours duration in analytical chemis- try and most have an option of following a further course of 25 hours. ,41so, students of Applied Biology have a lecture course of 20 hours. These courses are well supported by practical classes (more than 25 hours are provided each week of the university year) and together give the undergraduate direct experience of snalyt- ical chemistry with supplementation for those on analytical work during industrial training or final year projects.Despite the dearth of suitable texts, the challenge of preparing courses in which the lecture and practical material are inter-related has been stimulating and the results are appreciated by students.Some experiments involve minor investigations and literature surveys.170 ANALYTICAL CHEMISTRY IN UK UNIVERSITIES Proc. AnaZyt. Div. Chenz. Soc. The prominence of analytical chemistry in the undergraduate curriculum had the clear support of Mr. A. H. Henson, who headed the Chemistry Department until his retirement in 1976.The activity now has the enthusiastic approval of his successor, Professor David R. Williams. Research Teaching cannot thrive without the spirit of enquiry and research. Members of staff (J. D. R. Thomas, Reader; G. J. Moody, Senior Lecturer; P. M. May, Lecturer; T. P. Jones, Lecturer; P. J. F. Griffiths, Senior Lecturer; K. Fish, Lecturer; W. J. Criddle, Senior Lecturer; and R.Fielding, Demonstrator) concerned with teaching are also normally active with final year undergraduate projects and/or research. For research, the view’ of analytical chemistry as “the examination of a material to establish its properties, its qualities and the identification and/or determination of the amount of some or all of its constituents” needs to be broader and has to extend into the realm of methods for analytical chemistry, including an assessment of their advantages and limitations.Both methods and applications are represented in research activities relating to analytical chemistry a t UWIST and are supported by industry, Research Councils, Government Departments, charitable bodies, etc. Live Research Projects EJectvoanalysis By reason of its activities in ion-selective electrodes, TJWIST has had a considerable hand in one of the more recent and exciting develop- ments in electroanalytical chemistry.This is associated in particular with the new series of PVC matrix membrane ion-selective electrodes, first reported in what has turned out to be a regularly cited key paper.2 The work has led to several new ion-selective electrodes based on sensors of liquid ion exchangers, improvements in calcium ion-selective electrodes and assess- ments of the scope of tetraphenylborate salts of metal ion complexes of polyalkyleneoxyglycoIs as ion sensors.These areas are under con- tinuing study by J. D. R. Thomas, G. J. Moody, B. Doyle, N. S. Nassory, C. G. D. Jones, Ililys L. Jones and S.K. Hassan, as are develop- ments in the grafting of ion sensors to polymeric matrices. Ion buffers can be employed usefully to extend the calibration ranges of ion-selective electrodes and with computer techniques can be used in studies of free ion levels in the presence of complexing agents (Professor David I<. Williams, J. D. R. Thomas, G. J. Moody, P. M. May and A. Craggs) .Crystal membrane ion-selective electrodes are also of considerable interest (J. D. R. Thomas, G. J . Moody, E. Jane Duffield, D. J . Crombie and N. S. Nassory). Applications such as monitoring sulphide produced by sulphate- reducing bacteria, or thiols in process streams, and examining causes of failure and restrictions in detection limits are still under scrutiny. Such work with the copper(T1) ion-selective electrode has involved co-operation from University College, Swansea, a sister college to UlYIST within The University of Wales ; in this work the Auger spectroscopic patterns of electrode mem- branes have been assessed in relation to their potentiometric behaviour.Co-operative programmes are a regular characteristic of the Science Research Council’s CASE i4ward Scheme.The industries con- nected with these programmes in analytical chemistry a t UWIST (Unilever Research, ESSO Research, EDT Research, etc., each in associa- tion with J . D. R. Thomas and G. J . Moody) provide opportunities for additional stimuli during postgraduate research training. This also applies to those projects fully supported by industry, such as the present project in\-olving Lion Laboratories in another area of electro- analysis in which the nature of a novel range of fuel cells as sensors for determining ethanol and other vapours is examined (T.P. Jones, 31. Xeame and M. G. Carter). Polarography has its stake in the possible analytical role of the effect of imidazoles on the half-wave potential of copper(I1) - copper(1) in the presence of citrate (J.D. R. Thomas, G. J . Moody and G. C . F. Clark). Sepavations and extvacfiom A closc association exists with J. Harvey and Sons in work on the sherry maturation process (W. J. Cricldle). This involves solvent extrac- tion and gas chromatography - mass spectro- metry and highlights Criddle’s more general interests in gas chromatography and HPIX. These interests have resulted in pyrolysis - gas chromatography met h ocls for the simultaneous chromatographic determination of paraquat and diquat in pond and river waters and cetri- mide in pharmaceutical preparations.Con- tinuing work on determining herbicide traces and assessing the tainting of potable water supplies (in conjunction with The \Trelsh l17ater Authority) is coupled with studies o f the thermal breakdown of tertiary ammonium compounds (W. J.Cricldle, Judith Thomas and Sandra J. Lucas) .-Way, 1979 ANALYTICAL CHEMISTRY I N UK UNIVERSITIES 171 Interest in the scope of ion exchange and electrophoresis in non-aqueous and mixed solvent systems continues and the ion-exchange sorption properties of surfactants are currently under study (J. D. R. Thomas, G.J. Moody and J. 0. Rutherford). A new tack is the use of foams for supporting liquid ion exchangers and solvent extractants for analytical separations and extractions and this work is helped along by a link with Eotvos University, Budapest (J. D. R. Thomas, G. J. MoodyandM. Maloney). Studies of ion transport through PVC matrices containing various selective agents are well under way.An interesting phenomenon of possible analytical use is the transport of ions against their concentration gradients (J. D. R. Thomas, G. J. Moody and B. Doyle with advice from P. J . F. Griffiths on the use of radio- tracers). Activities outside the chemistry depavtvnent As in other universities, departments other than chemistry have interests in analytical chemistry.Thus, nutritional and other studies of vitamin C in applied biology have stimulated an ion-exchange stage in order to improve the analysis of urinary vitamin C (R. E. Hughes). However, as was recently emphasised by S e l b ~ , ~ it is in pharmacy that analytical chemis- try can occupy a central problem-solving role. In consequence, there are several research lines in pharmacy related to analytical chemis- try.The principal ones concern various pro- cedural improvements and separations by gas, high-performance liquid and thin-layer chro- matography (M. S. F. Ross, P. J. Nichols, D. K. Luscombe, K. R. Brain, P. Girgis-Takla and T. D. Turner) and, of course, particle size analysis (M. I. Barnett and N. A. Armstrong). Kuclear magnetic resonance is focused on methods for determining drugs and related materials, for example, pyrimethamine (V.Askam). Atomic spectroscopy features in determi- nations of lead in plastic containers (P. Girgis- Takla and I. Chroneos). General More general research activities necessarily often involve analytical chemistry. Those in pharmacy as well as those projects in chemistry on compounds of medicinal interest, for example, on the synthesis of chromones, thioamides and ylidenemalononitriles, are heavily dependent on the kind of analytical procedures and methods so vividly expressed by Selby3 as the hub of pharmaceutical development.The pollution and ecological researches of applied biology are also heavily dependent on analytical chemistry and particularly on atomic spectroscopy for assessments of metal contamination in rivers, etc.Even developments in analytical chemistry itself will use established methods, as in the synthesis and appraisal of new ion-selective electrode materials where nuclear magnetic resonance (with advice from K, Fish), ultra- violet and infrared spectroscopy, elemental analysis, gel permeation and thin-layer chro- matography, atomic spectroscopy, radiotracer methods, potentiometry, permittivity methods, etc., have all played their part (J.D. R. Thomas and others). Within this group, members participate in weekly seminars and each member is required to present a talk once every six to eight weeks. Furthermore, written reports are required monthly as evidence of progress. Such experience is complemented by periodic reports to sponsors and participation and attendance a t departmental colloquia and at meetings outside UWIST.Conclusion The breadth of analytical chemistry is such that a single department or institution cannot cover all facets. There must be specialisation and in research members of UWIST concentrate within the areas of electroanalysis and separa- tion. However, the above experiences and the availability and general use of a wide range of analytical methods ensure a full picture of analytical chemistry. This is enriched by many links, manifested by visits and exchanges by several individual researchers between UWIST and universities and other establish- ments in Britain, Eastern and Western Europe, the Middle and Far East, the TJSA, Africa and Australia. References 1. Jones, A. G., Proc. Soc. Analyt. Chem., 1073, 2. Moody, G. J., Oke, R. B., and Thomas, 3. Selby, I. A., Chemistry in Britain, 1978, 14, 10, 101. J. D. R., Analyst, 1970, 95, 910. 606. J. D. R. Thomas Chemistry Department, Redwood Building, UWIST, Cardifl, CF 1 3N U

ISSN:0306-1396    

DOI:10.1039/AD9791600169

出版商:RSC    

年代:1979

数据来源: RSC

摘要:

172 ROBERT BOYLE ESSAY AWARDS Proc. A.lzalyt. Div. Chem. soc. Evaluation and Optimization of Laboratory Methods and Analytical Procedures. A Survey of Statistical and Mathematical Techniques. Desirk L. Massart, Auke Dijkstra and Leonard Kaufman. Techniques and Instvumentation in Analytical Chemistry, Volume 1. Pp. s v i $- 596. Amsterdam, Oxford and New ’l’ork: Elsevier. 1978. Price $57.75; Df1130.00.Publications Received Progress in Analytical Atomic Spectroscopy Editor-in-Chief C. L. Chakrabarti. Volume 1, Nos. 1/2. Pp. iv + 200. Oxford and New York: Pergamon Press. 1978. Subscription price ,523.63; $52. A New Journal. Air Pollution Sampling and Analysis Desk- book. Edited by Paul N. Cheremisinoff and Angelo C . Morresi. Pp. vi + 490. Ann Arbor, Mich.: Ann Arbor Science Publishers.Distributed by John Wiley, Chichester. 1978. Price fll8.60. The Analysis of Nutrients in Food. D. I<. Osborne and P. Voogt. Food Science and Technology: A Series of Monographs. Pp. xvi + 252. London, New York and San Francisco : Academic Press. 1978. Price L10.50; $21.76. Statistique Appliquee a I’Exploitation des Mesures. Tonies 1 and 2. Commisariat B 1’Energie Atomique. Tome 1 , pp.xx + 1-148 + 1-128; Tome 2, pp. sii + 149415. Paris, New York, Barcelona and Pl‘lilan : Masson. 1978. Heteroepitaxial Semiconductors for Elec- tronic Devices. Edited by G. W. Cullen and C. C. FVang. Pp. xx + 300. Berlin, Heidelberg and New York: Springer-Verlag. 1978. Price $79.00; DM158. Liquid Scintillation Counting. Volume 5 . Edited by M. A. Crook and P.Johnson. Pro- ceedings of a Symposium on Scintillation Counting organised by the Radiochemical Methods Group (Analytical Division, The Chemi- cal Society), Bath, England, September 13-16, 1977. Pp. x + 222. London, Philadelphia and Rheine: Heyden. 1978. Price $28; L14; DM64.50. Transform Techniques in Chemistry. Edited by Peter R. Griffiths. Pp. xxii + 386. London, Philadelphia and Rheine : Heyden. 1978.Price L25.25; DM161.50. Silicones Under the Monogram. A Story of Industrial Research. Herman A. Liebhafsky. Pp. xviii + 382. Chichester, New York, Brisbane and Toronto : John Wiley. 1978. Price ,515.70; $31. Physicochemical Application of Gas Chro- matography. Richard J. Laub and Robert L. Pecsok. Pp. xxiv + 300. Chichester, New York, Brisbane and Toronto: John Wiley.1978. Price jJ6.60; $33.May, 1979 COURSES Photoelectron Spectroscopy and Molecular Orbital Theory. R. E. Ballard. Pp. xii + 192. Bristol: Adam Hilger. 1978. Price +J8.00. Carbon Adsorption Handbook. Edited by Paul N. Cheremisinoff and Fred Ellerbusch. Pp. x + 1054. Ann Arbor, Mich. : Ann Arbor Science Publishers. Distri- buted by John Wiley, Chichester.1978. Price L25.15. Instrumentation for High-Performance Liquid Chromatography. Edited by J. F. K. Huber. Journal of Chro- matography Library, Volume 13. Pp. xvi + 204. Amsterdam, Oxford and New York: Elsevier. 1978. Price $34.75; Dfl80. Electron Microscopy and X-ray Applica- tion to Environmental and Occupational Health Analysis. Edited by Philip A. Russell and Allan E. Hutchings. Pp. x + 278. Ann Arbor, Mich.: Xnn Arbor Science Publishers. Distributed by John Wiley, Chichester. 1978. Price L17.65. An Introduction to Microscopy by Means of Light, Electrons, X-Rays, or Ultrasound. Theodore George Rochow and Eugene George Rochow. Pp. xvi + 368. New York and London : Plenum. Price L18.5S. 173

ISSN:0306-1396    

DOI:10.1039/AD979160172b

出版商:RSC    

年代:1979

数据来源: RSC

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COURSES 173 May, 1979 Courses Radioisotope Techniques J u n e 18-22, 1979, Loughborough The Department of Chemistry of Loughborough University of Technology is holding its twenty- third Summer short course in Radioisotope Techniques, June 18-22, 1979. Practically biased, the course provides a broad outline of current radiochemical methods and is suitable for scentists in both industry and the teaching profession.Fee, including full accommodation, is Ll20. Enquiries to G. Oldham, Department of Chemistry, University of Technology, Lough- borough, Leicestershire, LE11 3TU. Postgraduate Summer School on Spectroscopic Interpretation J u l y 2-13, 1979, Manchestev The Summer School, to be held at the Depart- ment of Chemistry, University of Manchester Institute of Science and Technology, will con- sist of three complementary but self-contained courses : (1) Interpretation of Infrared and NMR Spectra (July 2-6).( 2 ) W/1H NMR Interpretation (July 9-13). (3) Interpretation of Mass Spectra (July 9- 13). All enquiries should be addressed to the Registrar, UMIST, P.O. Box 88, Manchester, M60 1QD. Automatic Methods of Analysis July 9-13, 1979, Swansea The Chemical Society is organising a Summer School, to be held a t the University College of Swansea, concerned with new developments in technique and the economic rationale of adopted methods.Lectures, laboratory sessions and group discussions will be included. Topics include automated methods of clinical analysis, segmented continuous flow analysis and flow injection analysis, the problems associated with the automation of single test analysis, GLC spectral and kinetic methods of analysis, the proper use of computers (main frame to micro) and the problems facing the laboratory manager who is considering automation.There will be basic lectures on electronics and the construction of automated systems in the laboratory. For further details, contact Mrs.Susan Leclerq, The Chemical Society, Burlington House, Piccadilly, London, W 1V ORN. Blood Drug Analysis August 28-September 8, 1979, Guildford The Wolfson Bioanalytical Centre is organising an intensive workshop course for novices on the above topic. Full details can be obtained from the Wolfson Rioanalytical Centre, University of Surrey, Guildford, Surrey, GU2 5XH. Environmental Air Pollution November 11-16, 1979, Louglaborough This course is intended for people with special responsibilities for environmental air pollution control, and will include lectures, films, demon- strations and an industrial visit. A wide range of topics includes the detection, identification and control of odours; pollutants in the working environment ; sampling from stack emissions ; and measurement and monitoring of trace elements. All enquiries to the Centre for Extension Studies, Loughborough University of Techno- logy, Loughborough, Leicestershire, LE 1 1 3TU.

ISSN:0306-1396    

DOI:10.1039/AD9791600173

出版商:RSC    

年代:1979

数据来源: RSC