摘要:

Proceedings of the Society for Analytical Chemistry CONTENTS The Analyst Editorial Advisory Board . . . . .. .. Reports of Meetings . . . . Retiring Chairman of TheAnalyst Editorial Committee.. .. Summaries of Papers “Preparation of High-Purity Sub- stances” . . . . . . “Gel Filtration and Gel Permea- tion” . . . . . . . . Papers Accepted for The Analyst Notices . . . . . . . . Announcements . . . . . . I 2 4 5 8 10 10 12 Proc. SOC. Analyt. Chem. Vol. 6 No. I Pages 1-14 Forthcoming Meetings . . Back cover January 1969 Vol. 6 No. I PROCEED1 NGS OF January 1969 THE SOCIETY FOR ANALYTICAL CHEMISTRY President of the Society A. G. Jones Hon. Secretory of the Society W. H. C. Shaw Hon. Treasurer of the Society G. W. C. Milner Hon. Assistant Secretaries of the Society D. I. Coomber; D.W. Wilson Secretary Miss P. E. Hutchinson 9/10 SAVILE ROW LONDON W.1 Telephone 01-734 6205 Editor 1. B. Attrill Telephone 01-734 3419 Proceedings is published by The Society for Analytical Chemistry and distributed to all members of t h e Society and to subscribers w i t h The Ano/yst;:subscriptions cannot be accepted for Proceedings alone. --d - Single copies maybe obtained direct from the Society’s Distribution Agents The Chemical Society Publications Sales Office Blackhorse Road Letchworth Herts. (NOT through Trade Agents) price 0 The Society for Analytical Chemistry 5s. post free. Remittances MUST accompany orders. Methods for the Analysis of Non-Soapy Detergent (NSD) Products by G. F. LONGMAN BSC. F.R.I.C. & J. HILTON B.SC. A.R.I.C. (Unilever Research Laboratory f o r t Sunlight) Society for Analytical Chemistry Monograph No. I -+- This Monograph describes in detail the methods of analysis developed in Unilever’s Laboratories for the identification and assay of components of NSD Products. -0- Available ONLY from The Society for Analytical Chemistry Book Department 9/10 Savile Row London W.I. (Not through Trade Agents) Price 15s. o r U.S. $2.00 Post free A remittance made o u t to “Society for Analytical Chemistry” should accompany every order. Members of the Society may purchase copies at the special price of 5s. post free.

ISSN:0037-9697    

DOI:10.1039/SA96906FX001

出版商:RSC    

年代:1969

数据来源: RSC

摘要:

2 REPORTS OF MEETINGS [Proc. SOC. Analyt. Chem. Reports of Meetings NORTH OF ENGLAND SECTION AN Ordinary Meeting of the Section was held at 7 p.m. on Friday December 6th 1968 at the Blossoms Hotel Chester. The Chair was taken by the Chairman of the Section Dr. W. Cule Davies F.R.I.C. A lecture on “Alcohol and Drugs in Blood and Urine,” was given by A. S. Curry M.A. Ph.D. F.R.I.C. WESTERN SECTION A JOIKT Meeting of the Western Section with the Cardiff and District Sections of the Royal Institute of Chemistry and the Society of Chemical Industry was held at 7 p.m. on Friday December 13th 1968 at University College Cathays Park Cardiff. The Chair was taken by Dr. L. E. Coles B.Pharm. F.P.S. F.R.I.C. representing the three participating Societies. A lecture on “Progress in Drug Control,” was given by D.C. Garratt Ph.D. D.Sc. F.R.I.C. H0n.M.P.S. MIDLANDS SECTION A JOINT Meeting of the Midlands Section with the Midlands Section of the Royal Institute of Chemistry was held at 6.30 p.m. on Wednesday December l l t h 1968 in the Haworth Lecture Theatre Chemistry Department The University Birmingham 15. The Chair was taken by the Chairman of the Midlands Section Mr. H. E. Brookes B.Sc. F.R.I.C. A lecture on “The Precipitation and Determination of Anions with Organic Reagents,” was given by W. I. Stephen Ph.D. F.R.I.C. NORTH EAST SECTION A JOINT Meeting of the North East Section with the Newcastle Section of the Oil and Colour Chemists’ Association was held at 6.30 p.m. on Thursday December 5th 1968 at the Royal Turks Head Hotel Newcastle upon Tyne. The Chair was taken by the Chairman of the North East Section Mr.F. C. Shenton F.R.I.C. A.R.T.C.S. The subject of the meeting was “Some Analytical Topics of Interest to the Paint Industry” and the following papers were presented and discussed “The Use of Scintillation Counting for the Investigation of Adsorption Phenomena in Paints,” by K. Goldsbrough ; “Practical Applications of the Potassium Bromide Wedge and of Inter-esterification Tech- niques in Paint Analysis,” by E. L. Deeley; “The Detection and Identification of Residual Solvent in Thin Paint Films,” by R. A. Turner; “The Determination of the Tributyltin Radical in Sea Water at the Parts per Million Level,” by C. N. Bell and F. R. Boynton. MICROCHEMICAL METHODS GROUP THE twenty-fifth Annual General Meeting of the Group was held at 6.30 p.m. on Friday November 29th 1968 in Lecture Theatre 664 Department of Mechanical Engineering Imperial College London S.W.7.The Chair was taken by the Chairman of the Group Mr. T. R. F. W. Fennell B.A. The following office bearers were elected for the forthcoming year Chairman-Dr. G. Ingram. Vice-Chairman-Mr. S. Bance. Honorary Secretayy- Mrs. D. E. Butterworth Division of Chemical Standards National Physical Laboratory Teddington Middlesex. Honorary Treasurer-Mr. F. H. Oliver. Members of Committee- Mr P. R. W. Baker Mr. T. R. F. W. Fennell Mr. A. T. Masters Mr. A. C. Thomas Dr. D. Thorburn Burns and Mr. D. W. Wilson. Mr. H. Childs and Mr. C. Whalley were re- appointed as Honorary Auditors. The Annual General Meeting was followed by a Group Dinner. c The sixty-sixth London Discussion Meeting of the Group was held at 6.30 p.m.on Tuesday December loth 1968 at “The Feathers,” Tudor Street London E.C.4. The Chair was taken by the Chairman of the Group Dr. G. Ingram M.Sc. A.R.I.C. A discussion on “The Use of Instruments in Practical Inorganic Analysis’’ was opened by D. A. Pantony T.D. B.Sc. Ph.D. A.R.C.S. SPECIAL TECHNIQUES GROUP THE twenty-fourth Annual General Meeting of the Group was held at 7 p.m. on Tuesday November 19th 1968 in Lecture Theatre “C,” Chemistry Department Imperial College London S.W.7. The Chair was taken by the Chairman of the Group Dr. T. L. Parkinson B.Sc. F.R.I.C. The following office bearers were elected for the forthcoming year Chair- man-Dr. T. L. Parkinson. Honorary Secretary and Treasurer-Dr. P. B. Smith Research Department Albright & Wilson (Mfg.) Ltd.P.O. Box No. 3 Oldbury Warley Worcestershire. Members of Committee-Mr. P. E. Arnold Mr. F. E. Banyard Mr. W. Boardman Dr. G. M. S. Duff and Mr. J. K. Foreman. Mr. R. A. C. Isbell and Mr. S. G. E. Stevens were re-appointed as Honorary Auditors. The Annual General Meeting was followed by an Ordinary Meeting of the Group at which the following papers were presented and discussed “Orion Electrodes,” by A. E. Bottom M.Sc. F.R.I.C. ; “Ion-selective Membrane Electrodes with Silicone Rubber as Supporting Material,” by A. M. G. Macdonald M.Sc. Ph.D. Vice-Chairman-Dr. J. H. Glover. THERMAL ANALYSIS GROUP THE fourth Annual General Meeting of the Group was held at 6.30 p.m. on Friday November 15th 1968 in the Meeting Room of the Geological Society of London Burlington House London W.l.The Chair was taken by the Chairman of the Group Dr. J. P. Redfern F.R.I.C. Chairman- Dr. J. P. Redfern. Vice-Chairman-Dr. D. Dollimore. Honorary Secretary-Mr. C. J. Keattch Industrial and Laboratory Services P.O. Box 9 Lyme Regis Dorset. Honorary Treasurer-Dr. A. A. Hodgson. Members of Committee-Dr. B. R. Currell Dr. R. A. W. Hill Dr. R. C. Mackenzie Mr. I. C. H. May Mr. R. P. Miller and Dr. J. H. Sharp. Dr. W. Boardman and Dr. T. L. Parkinson were re-appointed as Honorary Auditors. The Annual General Meeting was preceded by an Ordinary Meeting of the Group at which the following papers were presented and discussed “Some Applications of Differential Thermal Analysis to the Analysis of Oils and Fats,” by K. E. Berger; “Heat Transfer and Coal Pyrolysis,” by W. B. Davies and D.J. Brown; “Thermal Degradation Studies of Elastomers,” by D. A. Smith and J. W. Youren; “Thermogravimetric and Differential Thermal Analysis Studies of Poly (m-Aminostyrene) and Related Polymers,” by P. B. Jones R. H. Still and A. L. Mansell; “The Vacuum Pyrolysis of Poly(m-Aminostyrene),” by P. B. Jones and R. H. Still. The following office bearers were elected for the forthcoming year. RADIOCHEMICAL METHODS GROUP THE second Annual General Meeting of the Group was held at 6 p.m. on Monday November 18th 1968 at the Pharmaceutical Society 17 Bloomsbury Square London W.C.l. The Chair was taken by the Chairman of the Group Mr. D. A. Lambie B.Sc. F.R.I.C. The following office bearers were elected for the forthcoming year Chairman-Dr. H. J. M. Bowen. Honorary Secretary-Mr. M. A. Crook Depart- ment of Chemistry and Chemical Technology Borough Polytechnic Borough Road London S.E.l. Members of Committee-Dr. J. A. W. Dalziel Dr. D. S. Glass and Mr. J. Macmillan. Dr. F. J. Bryant and Dr. T. T. Gorsuch were re-appointed as Honorary Auditors. The Annual General Meeting was followed by an Ordinary Meeting of the Group at which the retiring Chairman D. A. Lambie B.Sc. F.R.I.C. gave an address entitled “Problems in the Provision of Radioactive Materials.” The Chair at this meeting was taken by the new Chairman of the Group Dr. H. J. M. Bowen M.A. Vice-Chairman-Dr. S. J. Lyle. Honorary Treasurer-Dr. D. I. Coomber.

ISSN:0037-9697    

DOI:10.1039/SA9690600002

出版商:RSC    

年代:1969

数据来源: RSC

摘要:

THE SOCIETY FOR ANALYTICAL CHEMISTRY 13 Forthcoming Meetings co.tztinued Thursday 20th LONDON Friday 21st CHEPSTOW Saturday 22nd LIVERPOOL Tuesday 25th NEWCASTLE Wednesday 26th LONDON Thursday 27th LONDON BIOLOGICAL METHODS GROUP Meeting on “Methods of Estimating Allergenic “The Clinical Background of Penicillin Hypersensitivity,” by H. P. Lambert. “Control Methods for Allergenic Impurities in 6-APA and Penicillins,” by “Correlation of Laboratory and Clinical Observations on Hypersensitivity to Meeting Room of the Pharmaceutical Society 17 Bloomsbury Square Properties Associated with Antibiotics.” F. R. Batchelor and Miss J. Dewdney. P-Lactam Antibiotics,” by I?. W. Muggleton. London W.C. 1 ; 2.30 p.m. George Hotel Chepstow; 6.30 p.m. WESTERN SECTION Discussion Meeting on “Automatic Methods in Analysis.” NORTH OF ENGLAND SECTION.“The Application of Newer Techniques in the Analysis of Food Flavours,” Lecture Theatre City Laboratories Mount Pleasant Liverpool ; 2.30 p.m. NORTH EAST SECTION jointly with the Newcastle and North East Coast Section of the Royal Institute of Chemistry. “Forensic Science,” by S. Denton. The University Newcastle upon Tyne; 6.30 p.m. ATOMIC-ABSORPTION SPECTROSCOPY GROUP. Meeting at and visit to Imperial College. Speakers to include K. C. Imperial College South Kensington London S. W. 7. CHROMATOGRAPHY AND ELECTROPHORESIS GROUP and RADIOCHEMICAL London. by K. Durham. Thompson. METHODS GROUP. 14 THE SOCIETY FOR ANALYTICAL CHEMISTRY January Wednesday 22nd LOUGHBOROUGH Wednesday 22nd DURHAM Friday 24th EDINBURGH Saturday 25th MANCHESTER February Wednesday 5th LONDON Thursday 13th MANCHESTER Wednesday 19th STOKE-ON-TRENT Wednesday 19th MANNINGTREE Forthcoming Meetings MIDLANDS SECTION.“14-MeV Neutron Activation Analysis,” by G. F. Oldham. Lecture Room J .002 Edward Herbert Building Department of Chemistry University of Technology Loughborough ; 6.30 p.m. Followed by a visit to the Nuclear Chemistry Laboratories. NORTH EAST SECTION Annual General Meeting followed by an Ordinary “The Examination of Antiquities,” by A. E. Werner. Lecture Theatre CG91 Department of Chemistry The University South SCOTTISH SECTION Annual General Meeting followed by an Ordinary “Silicate Chemistry at 2000’ C and 20,000 Atmospheres,” by G. M. Biggar. “U - Pb Isotopic Stability in Zircons,” by R. T. Pidgcon. “Geochemical Aspects of Recent Manganese Nodules,” by N.B. Price. Room D34 Heriot-Watt University Chambers Street Edinburgh 1 ; 5 p.m. NORTH OF ENGLAND SECTION Annual General Meeting followed by the Midland Hotel Manchester ; 2.30 p.m. Meeting. Road Durham; 6.30 p.m. Meeting on “Geochemical Aspects of Analysis.” Address of the Retiring Chairman W. Cule Davies. SOCIETY Meeting organised by the Special Techniques Group jointly with the Spectroscopy Group of the Institute of Physics on “Radiofrequency Spectroscopy.” “Microwave Spectroscopy of Gases as an Analytical Tcchnique,” by Professor J. Sheridan. “Electron Resonance-An Introductory Survey,” by Professor D. H. Whiffen. “Possible Analytical Applications of Electron Resonance,” by G. R. Luck- hurst. Wellcome Building Euston Road London N.W.l; 3 p.m. NORTH OF ENGLAND SECTION and AUTOMATIC METHODS GROUP Discussion Meeting on “Automatic Chemistry Systems.” Speakers A. H. Gowen Lock and P. G. Jeffery. University of Manchester Institute of Science and Technology Manchester 1 ; 6.30 p.m. MIDLANDS SECTION jointly with the Midlands Section of the Royal Institute of Chemistry. “Electrophoresis,” by G. F. Reynolds. Stoke-on-Trent. EAST ANGLIA SECTION Meeting on “The Analysis of Plastics Formulations.” “The Impact of Physical Sciences on Polymers and Copolymers of Styrene,” “The Identification and Determination of Some Phenolic Stabilisers in “Determination of Certain Additives in Polyethylene and Polystyrene,” by Bakelite Xylonite Ltd. Lawford Place Manningtree; 2.30 p.m. by T. B. Gay. Polyolefins,” by L. H. Ruddle. J . T. Davies. [coPztimed inside back cover Printed by W Heffer & Sons Ltd Cambridge England

ISSN:0037-9697    

DOI:10.1039/SA96906BX003

出版商:RSC    

年代:1969

数据来源: RSC

摘要:

4 RETIRING CHAIRMAN OF THE ANALYST EDITORIAL COMMITTEE [Proc. SOC. Analyt. Chem. The Retiring Chairman of The Analyst Editorial Committee The Analyst Editorial Committee and its fore-runner in all but name the Publication Com- mittee have been responsible for The Analyst from its inception in 1876 until the change just made to the publication of the journal under the auspices of an international Editorial Board and Executive Committee. Although the President of the Society has acted as Zocum tenens for the past nine months while this change has been under discussion the last Chairman of The Analyst Editorial Committee was Dr. K. A. Williams B.Sc. Ph.D. (Lond.) F.R.I.C. A.Inst.P. M.Inst.Pet. during whose ten years of office the journal’s development has been a t its greatest. K. A. Williams joined the Society in 1926 when he was working for E.R. Bolton the then President. He became a member of the Publica- tion Committee in 1939 at a time when the application of physical techniques to analytical chemistry was becoming important and remained a member (Chairman since 1958) while the tech- niques that are now so numerous and so familiar found early recognition in the pages of The Analyst. As Honorary Secretary of the Society and as a member of the Committee he took a considerable part in the planning of Analytical Abstracts which resumed the publication of abstracts for the Society in 1954 after 4 years during which the British Abstracts C was supplied to members and subscribers ; before 1950 abstracts had appeared in The Analyst since the earliest issues. As Chairman he had much to do with the development of the Proceedings and took an active part in the work of The Analyst Development Committee whose deliberations led to the Society’s two primary journals having their present form.He is professionally an Analyst and Technical Consulting Chemist specialising in the analysis and technology of oils fats and related foods. His interests cover many other subjects including giving expert advice on claims arising from damage to goods in transit and on shipping problems generally on patent matters and on litigation. He was President of our Society in 1955 and 1956 having served as Honorary Secretary from 1947 to 1955. In the oils and fats field he has been President (1950-51) of the International Commission for the Study of Fats (now the Oils and Fats Section Inter- national Union of Pure and Applied Chemistry). He was twice a delegate to the Council of I.U.P.A.C. His activities in the British Standards Institution include the Chairmanship of the Oils Fats and Surface Active Agents Industry Committee and of a number of technical commit tees. He is an established authority on the analysis of oils fats and fatty foods having written many original papers and is best known as the author of the third and (current) fourth editions of “Oils Fats and Fatty Foods their Practical Examination.” He rowed for the University of London Boat Club and for the Thames Rowing Club of which he is now Vice-president and has been coaching Queens’ College Cambridge and many other crews with success over many years. Dr. I(. A. Williams He is an expert amateur photographer and can claim to be an artist and sculptor.

ISSN:0037-9697    

DOI:10.1039/SA9690600004

出版商:RSC    

年代:1969

数据来源: RSC

摘要:

January 19691 PREPARATION OF HIGH PURITY SUBSTANCES 5 Preparation of High Purity Substances The following are summaries of some of the papers presented at a Joint Meeting of the Midlands Section and the Special Techniques Group with the Midlands Section of the Royal Institute of Chemistry held on September 25th 1968 and reported in the October 1968 issue of Proceedings (p. 195). The Separation of Milk Proteins by Column Chromatography BY L. IRONS AND M. JONES COLUMN chromatography is one of a number of separation methods dependent on migration for which the driving force is the flow of moving phase relative to the stationary phase and the resistive force is one of attraction to the stationary phase. The types of column chromato- graphy commonly used for protein separations based on the interaction between protein and stationary phase are adsorption ion exchange and molecular sieve chromatography (gel filtration).Adsorption chromatography has been used successfully for many enzyme preparations with calcium phosphate as adsorbent but difficulties are often encountered arising from irreversible adsorption of the protein and lack of reproducibility in the behaviour of the adsorbent. Ion-exchange chromatography is the most widely used technique for protein separations ; the supporting phases in common use being ion-exchange resins and ion-exchange celluloses. Limitations to the use of resins for protein separations are imposed by their cross-linked struc- ture low exchange capacity and hydrophobic nature but they have been used successfully for the separation of small molecules such as peptides and for some proteins especially those of high-isoelectric point and low molecular weight.The modified celluloses carboxymethyl cellulose and diethylaminoethyl cellulose have been widely applied to protein separations as their swollen hydrophilic matrices are readily permeable to large molecules. Elution from these adsorbents is achieved by changing the pH or increasing the salt concentration of the eluant to reduce the number of electrostatic bonds between the protein and the cellulose. Column chromatography on diethylaminoethyl cellulose can be used to purify the maj or casein and whey protein fractions of milk. Whole casein consists of a mixture of proteins which are separated from milk by acidification to pH 4-6 a t room temperature. Moving- boundary electrophoresis resolves whole casein into a- P- and y-caseins.The a-casein fraction can be further separated into calcium-insoluble as-casein and calcium-soluble K-casein. The full complexity of whole casein can only be demonstrated by the method of zoneelectro- phoresis in starch or polyacrylamide gels under conditions in which the casein aggregates are dispersed (7M urea). Whole casein is then resolved into about 20 components the high resolu- tion of the methods being obtained by a combination of charge and molecular-sieving effects. Crude forms of ccs- and p-caseins can be separated from whole casein by their different solubilities in aqueous urea solutions and then purified by chromatography on columns of diethylaminoethyl cellulose. Elution is carried out with 3 . 3 ~ urea and 0 .0 1 ~ imidazole buffers (pH7) and linear sodium chloride gradients ranging from about 0.1 to 0 . 3 ~ . The samples obtained in this way give mainly single bands on zone electrophoresis and are con- taminated with only trace amounts of other proteins. The major whey proteins P-lactoglobulin and a-lactalbumin can be obtained in a cry- stalline form by salt fractionation methods from the protein solution left after removal of casein from milk. However the proteins obtained are often impure even after several recrystallisations. They can be purified further by chromatography on diethylaminoethyl cellulose or by gel filtration on columns of Sephadex GlOO or G200. Separation of proteins by gel filtration depends only on molecular size and different molecules appear in the eluate in order of decreasing molecular weight.With whole whey the immunoglobulins are eluted first followed by bovine serum albumin P-lactoglobulin a-lactalbumin and finally the phos- phoglycoproteins. By using gel filtration as a final purifying stage samples of P-lactoglobulin and a-lactalbumin can be prepared from the impure crystalline preparations which give only single bands on polyacrylamide gel electrophoresis. (Unilever Reseavch Laboratovy The Fvythe Welwyn Hevts.) 6 PREPARATION OF HIGH PURITY SUBSTANCES [Proc. SOC. AnaZyt. Chem. Preparative-scale Gas Chromatography BY R. G. PLEVEY (Department of Chemistry The University Birmingham 15) GAS - liquid chromatography can be used to separate substantial amounts of material in two ways. In the first a chromatographic column of about the size conventionally used for analysis is used.Successive samples of the mixture are applied to the column and the chosen components collected by condensation from the gas emerging from the column. In the second method columns of much greater diameter (30 to 75mm) are used and to these are applied larger samples (1 to 50g) so that substantial amounts of chosen components can be obtained in a single pass by condensation from the emerging gas stream. Apparatus for the first method is available commercially. This paper is concerned with columns of the second type made in this department. The basic design of these instruments is similar to that of gas - liquid chromatographic apparatus available commercially. However larger columns either 30 or 75mm have generally been used. The columns are constructed from two 2-5-m lengths of glass or copper tubing joined together at one end copper tubes are preferable.The columns are packed with a stationary phase supported on Celite except for a portion below the inlet that is filled with metal shot. The columns are arranged vertically or horizontally in electrically heated ovens maintained at suitable temperatures. Samples fall by gravity from a glass vessel (designed so that there is little disturbance of the high back pressure of carrier gas at this point) on to the heated metal shot. The metal shot is usually heated to a temperature some degrees higher than the boiling-point of the least volatile component and this system allows a rapid transfer of heat to the injected sample. The rate of volatilisation is a factor that determines the efficiency of the column.At the other end of the chromatographic column a by-pass transfers about 1 per cent. of the effluent through a katharometer detector. Electronic amplification and recording on a moving-chart recorder of the signals resulting from thermal-conductivity changes in the effluent gas permit the controlled trapping by freezing into glass traps cooled in liquid air of components from the main gas stream. Optimum flow-rates of carrier gas for the smaller column (30mm) are about 15 to 20 litres per hour and for the larger column (75mm) are about 50 to 70 litres per hour. In the small columns from 0.5 to 3g of a single compound in a mixture can be dealt with and in the large columns about 10 to 25g. Fig. 1. The plateage (N) of a gas-chromatographic column Some idea of the efficiency of the columns can be obtained by comparing the performance of analytical columns with the 30 and 75-mm preparative tubes.The simplest way is to compare plateages of the columns working under optimum conditions. The plateage N is defined by the expression- January 19691 PREPARATION OF HIGH PURITY SUBSTANCES 7 Analytical columns usually accept samples of about 5p1. With the same sample loading per unit cross-sectional area of the column it is found that columns have plateage values of about 1000. However bearing in mind the different lengths of the columns (analytical 2m; preparative 5m) it appears that there has been a significant increase in the value of the height of the equivalent theoretical plateage given as the ratio of the column length to plateage.This decrease in efficiency even for relatively small samples has not been a serious problem as successful separations have been performed on 100 to 200-g samples in the 75-mm columns. The recovery from the columns varies between 75 and 95 per cent. depending to some extent on the retention times of compounds. In general separations take from 1 to 8 hours for completion. It should be assumed that materials may be contaminated with stationary phase or its decomposition products ; distillation in vacuo from phosphorus pentoxide is recommended. This bleed-off of stationary phase the so-called “ageing” of the tube is reflected in the gradual shortening of retention times leading to lower plateage values. Experience shows that this process does not seriously affect the performance of columns even after 2 or 3 years or more.The use of large diameter columns in preparative gas - liquid chromatography is a very effective method for separating considerable amounts of volatile materials (boiling-point less than 130 “C) and frequently adequate separations of less volatile mixtures are obtained. Laboratory Techniques of Metal Purification BY I. A. BUCKLOW (Metals Research Ltd. Melbouvn Royston Hevts.) SMALL-SCALE techniques for purification suitable for amounts of up to say 1 kg are described and reference is made solely to purification of metals and not to their compounds. Purification reactions are best conducted in the molten state when reaction rates and mobilities are high but the high temperatures normally required and the reactivity of molten metals often cause considerable difficulty in the choice of a suitable container; containers are therefore best avoided.Levitation would be the ideal state but it has considerable limita- tions and so compromise methods,in which the molten metal comes into contact only with its own kind are used. This is principally achieved in two ways viz. the floating zone and the water-cooled copper crucible. FLOATING-ZONE METHOD- First developed on a large scale for silicon the method involves the use of a vertical rod of metal supported at both ends by chucks that can rotate and move vertically. A small zone of molten material is established across the rod and held in place by surface tension; the zone traverses the rod and purification occurs partly by zone-refining (i.e. fractional crystallisation) and partly by preferential evaporation of impurities (in a vacuum) or by chemical reaction with an atmosphere.In practice the length of the zone is about the same as the rod diameter but as the molten metal is supported only by surface tension a practical limit on rod diameter is reached. The necessity for a sufficient surface tension restricts the method to metals with melting-points above about 1150" C. Rod dimensions are say up to 15mm diameter by 400 mm long and traverse speeds are from 2 to 20 mm per hour. The two principal methods of heating the zone are by electron- beam and radiofrequency induction heating. EZectyon-beam heating-This method requires an extremely good vacuum system (low leak-rate clean and well trapped) if back-streaming pump-oils etc. are not to introduce considerable contamination; beam heating is efficient and power supplies are not too expen- sive.The method is suitable for refractory metals where impurity evaporation is probably as important as zone refining. Radiofrequency induction heating-The generator is expensive but the heater can now be outside the reaction chamber therefore zoning can take place in neutral or reactive atmos- pheres at positive pressure. Evaporation losses of the parent metal are reduced and impuri- ties are removed by reaction with the gas (e.g. carbon is removed from iron as carbon mon- oxide by zoning in wet hydrogen). Induction heating can give some support to the 8 GEL FILTRATION AND GEL PERMEATION [Proc. SOC. Analyt. Chem. molten zone but heating is not very efficient and the method is most often used for metals melting at the lower end of the range.WATER-COOLED COPPER CRUCIBLE- Developed by Standard Telephone and Cables Research Laboratories Harlow Essex the crucible forms either a horizontal trough or a basket of water-cooled copper tubes; the metal charge is melted by an external radiofrequency induction coil. On an atomic scale there is only point contact between the crucible and molten metal within; the charge is frozen at these contact points which due to stirring in the melt are always changing hence the whole charge is effectively molten normally there is no contamination. Reactive atmos- pheres can be used and with the trough several zones can be passed at one time. SOLID-STATE ELECTROLYSIS- Solid-state purification is best avoided because it is slow inefficient and usually limited to impurities that can be converted into gases but solid-state electrolysis is a relatively new method and holds great promise; M.Whittaker at Metals Research is applying it very successfully to rare-earth metals (to be published in “Proceedings of the Second International Congress on Crystal Growth Birmingham U.K. 1968,” North Holland Publishing Co. Amsterdam). A rod is held vertically in a reaction chamber under pressure of argon (again good vacuum standards are required to prevent the ingress of oxygen) and a d.c. current of about 500A per cm2 is passed to heat the rod nearly to melting-point. After about 100 to 150 hours considerable proportions of the impurities the non-metallics especially have drifted to the anode end and are precipitated as inclusions. Crystalline perfection and purification levels are much higher than can be achieved by zoning and rod diameter is not limited by surface tension. SEMANTICS OF METAL PURIFICATION- The speaker thought that probably the only metal to have been truly purified to 99-9999per cent. (i.e. 6N) was tungsten; even the electronic metals which are quoted as 7N or even 9N are purified to this degree only in respect of electronically-active impurities. And yet some of the most reputable suppliers still claim 6N for a wide range of metals. The process that leads to these figures is one of “purification by omission,” in which the supplier (often unwittingly) omits to define the limits of analytical detection and often forgets altogether the existence of for example surface oxide on powders. A note of warning on the meaning of “purity” was given. Let the buyer beware!

ISSN:0037-9697    

DOI:10.1039/SA9690600005

出版商:RSC    

年代:1969

数据来源: RSC

摘要:

8 GEL FILTRATION AND GEL PERMEATION [Proc. Soc. Analyt. Chew. Gel Filtration and Gel Permeation The following are summaries of the papers presented at a Joint Meeting of the Midlands Section and the Special Techniques Group held on October 16th 1968 and reported in the November 1968 issue of Proceedings (p. 216). Sephadex Gel Filtration BY MRS. CELIA MALE (Pharmacia (Great Britain) Ltd. Paramount House 75 Uxbridge Road Ealing London W.5) SINCE its introduction in 1959 Sephadex gel filtration has become a widely used chrornato- graphic procedure both on an analytical and preparative scale. The product known as Sephadex is a white inert powder consisting of bead-shaped particles that swell in aqueous solvents to give a gel suspension. There are eight different Sephadex G-types that swell in aqueous solvents vix.G-10 G-15 G-25 G-50 G-75 G-100 G-150 and G-200. These differ only in their degree of cross-linkage and hence in their porosity and fractionation range. Dextran of bacterial origin is cross-linked with epichlorhydrin. January 19691 GEL FILTRATION AND GEL PERMEATION 9 Sephadex G-10 is the most highly cross-linked and the least porous (exclusion limit about molecular weight 700) while Sephadex G-200 is the least cross-linked and most porous gel (exclusion limit about molecular weight 800,000). Sephadex LH-20 is a lipophilic derivative produced by the introduction of hydroxy- propyl groups into Sephadex G-25. Sephadex LH-20 swells in polar organic solvents and has an exclusion limit of about molecular weight 5000. Slurries of swollen Sephadex particles can be packed into chromatographic columns or the superfine grade can be used for thin-layer chromatography.The resulting gel bed or layer can be used to separate molecules according to size. If no solute-gel interaction effects are in operation the elution position of molecules is determined by their molecular size. Large excluded molecules appear in the effluent first followed by molecules of de- creasing size. On each gel type the elution behaviour of a molecule can be characterised by a distribution coefficient K which is zero for excluded molecules and tends towards unity for very small freely diffusible molecules. Distribution coefficients greater than unity indicate that adsorption is taking place. The three main classes of separations that take place on Sephadex columns are “de-salting,” fractionation and those based on solute - gel matrix interaction effects.The separation of two or more species of molecule differing greatly in size with distri- bution coefficients approaching zero and unity has often been loosely referred to as de- salting because in the historical context the de-salting of high molecular weight materials such as proteins was one of the first practical applications of Sephadex gel filtration. De-salting is normally carried out on Sephadex G-25 and can be scaled-up to commercial proportions. The new Sephamatic gel filters are designed for industrial scale procedures. On the laboratory scale however this type of separation has numerous applications such as removal of low molecular weight impurities from macromolecules binding studies and labelling techniques.Sephadex gel filtration has become a widely used laboratory technique for the fraction- ation of complex mixtures or the separation of two or more components of a mixture in which the components do not differ greatly in molecular dimensions. The Sephadex gels cover a wide fractionation range. Sephadex G-10 can be used for the fractionation of molecules of molecular weight less than 700 while Sephadex G-200 the most porous gel is used for the fractionation of macromolecules. It is generally assumed that interaction effects occurring between the gel matrix and the molecular species under investigation are the basis of separations that do not fall into the above categories. Aromatic substances adsorb on to Sephadex gels and the separation of molecules containing aromatic groups but not necessarily differing in size is often possible.The presence of residual carboxyl groups on the Sephadex matrix causes adsorption of basic and exclusion of acidic compounds. These charge effects are predominant in distilled water and can be largely eliminated by the use of an eluant with an ionic strength of at least 0.02. Solute - gel interaction effects are greatest in the highly cross-linked gels particularly on Sephadex G-10. Gel Permeation Chromatography in Non-aqueous Solvents BY F. W. PEAKER (Chevnistvy Depavtment The Univevsity P.O. Box 363 Bivvnzxghavn 15) THE essential features of equipment required to carry out a gel permeation chromatographic analysis in organic solvents include a solvent de-gassing unit; a pump capable of operat- ing up to 300 p.s.i.; pressure-regulating valves; an injection loop; analysis and reference columns; a detector which is frequently a differential refractometer; and a syphon system to indicate each increment of elution volume passed through the system. Hot-wire detectors and infrared spectrometers have also been used to monitor the eluent but a differential refractometer with a sensitivity of lo-' units is probably the most versatile detector in general use. 10 GEL FILTRATION AND GEL PERMEATION [Proc. SOC. Analyt. Chem. High molecular weight material is excluded from the gel to a greater extent than material of lower molecular weight and a continuous recording of the refractive index of the eluent against elution volume is produced. This record may be converted into a weight distribution curve for the sample once the characteristics of the columns have been established by a study of the elution volumes of well characterised polymers of known molecular weight and narrow molecular weight distribution.After calibration the number weight viscosity and Z- average molecular weights of the samples can be calculated from the distribution curve. This method is most reliable in the measurement of the weight and viscosity average values as they are dependent upon the higher moments of the distribution curve. When calibration samples are not readily available and polystyrenes are the only materials available commercially a universal calibration curve can be drawn up by plotting the product of the limiting viscosity number and the molecular weight i.e. [q] x M against elution volume.This depends upon the assumption that gel permeation is determined by the equivalent hydrodynamic volume of the solute molecules in solution. This approach can be used to carry over the calibration to other polymers and also to branched-chain molecules. As an example of the use of this technique the degradation of natural and synthetic rubber by mechanical forces was discussed. The milling of a natural rubber brings about a narrowing of the molecular weight distribution to a state in which it is unaltered by further milling. In contrast polyisobutylene when degraded in solution produces a significant proportion of very low molecular weight material in the range 50 to 1300 molecular weight units. Cross-linked polystyrene is the most widely used column-packing material and can be made to be effective in the separation of materials of molecular weight of lo7 extending through a range of permeabilities to the least permeable gels capable of handling material of only 10 to 50 units. In this lowest range the separations must be regarded as purely preparative. Attempts at correlating molecular size with elution volume indicate the existence of inter- actions between the solute to be analysed and the packing material. Within an homologous series the elution volume increases with molecular weight but materials with identical mole- cular volumes frequently have different elution volumes depending upon the solvent used and the chemical nature of the solute. The presence of highly polar groups has a very pro- nounced effect.

ISSN:0037-9697    

DOI:10.1039/SA9690600008

出版商:RSC    

年代:1969

数据来源: RSC

摘要:

10 GEL FILTRATION AND GEL PERMEATION [Proc. SOC. Analyt. Chem. Papers Accepted for Publication in The Analyst THE following papers have been accepted for publication in The Analyst and are expected to appear in the near future. “Determination of Specific Gravity and Concentration of Fruit Juice Concentrations and Other Viscous Concentrated Solutions,” by H. B. Basker. “A Rapid Method for the Production Control of the Non-ionic Component in Synthetic Detergents,” by B. M. Milwidsky. “A Rapid Method for Detection of Residual Lipase Activity in Oat Products,” by T. Kazi and T. J. Cahill. “Determination of Trace Metal Contaminants in a Wide Range of Varied Chemicals by Means of the Technicon AutoAnalyzer,” by W. S. Sebborn. “Charge-transfer Chromatography of Polycyclic Hydrocarbons,” by G.D. Short and R. Young. “The Spectrophotometric Determination of Cationic Surfactants with Picric Acid,” by I. Sheiham and T. A. Pinfold. “Effective Removal of Oxygen from Nitrogen Carrier Gas in Gas - Liquid Chromato- graphic Analysis,” by K. Voldum-Clausen. “Preparation and Spectral Characteristics of Microwave-excited Electrodeless Discharge Tubes for Palladium Silver Platinum and Gold,” by K. M. Aldous R. M. Dagnall and T. S. West. “The Determination of Trace Amounts of Tellurium by Inorganic Spectrofluorimetry at Liquid Nitrogen Temperature,” by G. F. Kirkbright C. G. Saw and T. S. West. January 19691 INTERNATIONAL CALENDAR 1969 11 “The Determination of Total Fluorine in Air by a Micro-diffusion Technique,” by B. S. “The Determination of Selenium in Plant Samples,” by R. J. Hall and P. L. Gupta. “A Field Method for the Determination of Organic Aromatic Isocyanates in Air,” by Marshall and R. Wood. D. W. Meddle D. W. Radford and R. Wood. The Preparation of Slides for Lectures Reprints COPIES of “The Preparation of Slides for Lectures,” reprinted from Proceedings November 1968 Volume 5 No. 11 pp. 222 to 227 are now available from the Society for Analytical Chemistry Book Department 9/10 Savile Row London W1X lAF Price 1s. 6d.

ISSN:0037-9697    

DOI:10.1039/SA9690600010

出版商:RSC    

年代:1969

数据来源: RSC

摘要:

January 19691 March 10th-13th March 25th-29th May 5th-9th May 19th-24th May 26th-30th June 4th-7th June 5th-11th July 8th-10th July 14th-18th INTERNATIONAL CALENDAR 1969 International Calendar 1969 11 Symposia Conferences and Exhibitions Physics Exhibition Alexandra Palace ; organised by The Institute of Physics and Physical Society 47 Belgrave Square London s.w.l. LABEX International; Earls Court London E.C.4 organised by UTP Exhibitions Ltd. Racquet Court Fleet Street London E.C.4. Ninth Commonwealth Mining and Metallurgical Congress London ; write to Hon. Sec. 44 Portland Place London W.l. Fifth Radiochemical Conference Zvikov Czechoslovakia ; write to Ing. J. Alexa Institute of Nuclear Research Rex Prague. XVth International Colloquium on Spectroscopy Madrid ; write to Sr. Secretario Serrano 119 Madrid-6.Twenty-first Congress of Union of Textile Chemists and Colorists Baden-Baden ; write to Rohrbecherstr. 78 Heidelberg Fed. Rep. Germany. Fifth International Meeting of Forensic Sciences Toronto Canada; write to Mr D. M. Lucas MSc. 8 Jervis Street Toronto 2. International Symposium on Isotope Effects York; orgaucised by The Chemical Society Burlington House London WIV-OBN. International Atomic Absorption Spectroscopy Conference Sheffield ; organised by the Society for Analytical Chemistry (Atomic-Absorption Spectroscopy Group) 9/10 Savile Row London W. 1. 12 INTERNATIONAL CALENDAR 1969 [Proc. SOC. Avtalyt. Chem. July 15th-18th Symposium on N.M. R. Spectroscopy Birmingham ; organised by The Chemical Society Burlington House London WIV-OKN. July 17th-19th Symposium on Surface Area Determination School of Chemistry University of Bristol; write to Professor D.H. Everett School of Chemistry University of Bristol Bristol BS8 ITS. International Symposium on Analytical Chemistry Birming- ham; Midlands Section Society for Analytical Chemistry; write to D. M. Peake c/o Research Dept. Imperial Metal Industries Ltd. P.O.B. 216 Birmingham 6. August 11th-14th International Symposium on Electron and Nuclear Magnetic Resonance Clayton Australia; write to Dr C. J. Coogan CSIRO Clayton Victoria Australia 3618. Au gtl s t 2 0 t h - 2 7 t h Twenty-second International Congress of Pure and Applied Chemistry Sydney Australia ; write to Chairman Organising Committee Box 2249U GPO Melbourne Australia. Third International Clay Conference Tokyo Japan ; orgavtised by Institute of International Geology University of Tokyo Otsuka Bunkyo-ku Tokyo Japan. Fourth International Congress on Metallic Corrosion Amsterdam; write to Stichting Nederlandse Centrum Postfach 52 Delft Net herlands. July 21st-25th September 5th-1 lth September 7th-14th

ISSN:0037-9697    

DOI:10.1039/SA969060011b

出版商:RSC    

年代:1969

数据来源: RSC

摘要:

12 INTERNATIONAL CALENDAR 1969 [Proc. SOC. Aaalyt. Chem. Announcements For the analyst . . . The A.S.T.M. list of publications issued in September 1968 by the American Society for Testing and Materials is now available. This book is revised annually and the current issue contains 34 pages listing more than 500 A.S.T.M. publications dealing with the knowledge of materials evaluation and the standardisation of methods of test and specification for materials. The A.S.T.M. list of publications will be sent free of charge on request on company headed paper to Dept. HHH; A.S.T.M. 1916 Race St. Philadelphia Pa. 19103 U.S.A. B.D.H. Chemicals Ltd. Poole Dorset have available a new clinical assay set for the determination of D-glucose-6-phosphate NADP oxidoreductase. Glucose-6-phosphate dehydrogenase catalyses the oxidation of glucose-6-phosphate in the presence of nicotinamide adenine dinucleotide (NADP).The assay method is based on the spectrophotometric measurement at 340 nm of the rate of NADP reduction. The set provides glucose-6-phosphate substrate and NADP in dry form and magnesium buffer solution ready for use together with a leaflet detailing the test procedure. Each set provides for 25 tests; and reagents can be prepared for 5 tests at a time. A new range of reference beam attenuators the AT-04 AT-043 and AT-06 has been introduced by Research & Industrial Instru- ments Company. One of the most useful accessories at the disposal of the spectroscopist the reference beam attenuator allows the potentiality of a double-beam spectrophoto- meter to be more fully exploited than would otherwise be possible.The new attenuators incorporate simply controlled high precision combs that can attenuate a beam throughout the full range from 0 to 100 per cent. The spring-loaded cell slide can hold a matching fixed or variable path length cell for simultaneous attenuation and solvent compensation. A removable transmitting screen provides for sensitive linear adjustment in the lower part of the range. A set of screens with nominal trans- mission values of 8 16 26 30 40 and 50 per cent. is also available. The AT-04 and AT-043 have different external features to allow for use with various British and American infrared spectrophoto- meters the AT-06 is a special low-cost variant. A descriptive brochure is available from Research & Industrial Instruments Company Worsley Bridge Road London S.E.26.THE SOCIETY FOR ANALYTICAL CHEMISTRY 13 The Post-Graduate Education Centre A.E.R.E. Harwell announces a course of lectures on seventeen important modern physical tech- niques of analysis to be held from February 17th to 21st 1969. Lectures giving details of the scope limitations applications and inter- relation of these techniques will be presented by specialists actively engaged in these fields in industry universities and government labora- tories. Further details from The Post- Graduate Education Centre (MP) Building 455 A.E.R.E. Harwell Didcot Berkshire. Anderman & Company Limited announce that they will have available for T.L.C. aluminium sheets in rolls from E. Merck A.G. of Darmstadt. The rolls will be 20 cm wide and about 510 cm long so that about 500cm can actually be used.They will be more economical than the packs of the 20 x 20-cm sheets. This new development opens up interesting aspects for descending chromatography with longer travel- ling distance. Further details from Anderman & Company Limited Battlebridge House 87-95 Tooley St. London S.E.l. The Tecam Dip Cooler KU5 is a high-power compact portable refrigeration unit. The portable compressor case has a single flexible hose connection to the flat cooling coil. The coil occupies a minimum of space in the liquid the temperature of which is to be lowered and gives maximum working area within the bath. Efficient circulation of the bath liquid around the cooling element is achieved by attaching the heater controller circulation pump outlet to a connector on a cooling coil. This prevents a cold area forming around the element and ensures a uniform temperature throughout the bath. The RU5 will cool 2 gallons of methanol to -20" C in 45 minutes. The unit is recom.mended for use with the Tecam Constant Temperature bath in which the coil fits along the bottom of the bath. Further details are available from Techne (Cambridge) Ltd. Duxford Cambridge.

ISSN:0037-9697    

DOI:10.1039/SA9690600012

出版商:RSC    

年代:1969

数据来源: RSC