摘要:

Proceedings of the Society for Analytical Chemistry CONTENTS Reports of Meetings . . . . 113 Elwell Award Presentation . . 115 Thin-layer Chromatography . . 118 .. 124 Papers accepted for The Analyst 125 . . 126 Membership changes . . . . 126 Publications Received . . . . 127 . . 128 Notices .. Forthcoming Meetings . . Back cover Meeting . . . . Ionic Equilibria . . . . Obituary .. . . . . .. . . Proc. SOC. Anal. Chem. Vol. I No. II Pages 113-128 November 1964 Vol. I No. I I November I964 PROCEEDINGS THE SOCIETY FOR ANALYTICAL CHEMISTRY OF President of the Society D. C. Garratt Hon. Secretory of the Society S . A. Price Ron. Treasurer of the Society D. T. Lewis C.B. Hon. Assistant Secretaries of the Society B. S. Cooper; D. W. Wilson Secretary Miss P. E. Hutchinson 14 BELGRAVE SQUARE LONDON S.W.1 Telephone BELgravia 3258 Editor 1.B. A t t r i l l Proceedings i s published by The Society for Analytical Chemistry and distributed t o members and all subscribers t o The Analyst without charge Single copies may be obtained direct from the Secretary The Society for Analytical Chemistry a t the above address (NOT through Trade Agents) price 2s. 6d. post free. Remittances payable to “Society for Analytical Chemistry” MUST accompany orders Determination of Trace Elements with Special Reference to Fertilisers and Feeding Stuffs A Report of the Analytical Methods Committee Recommended methods for determining traces of- B Ca CI- Cr Co Cu F I Fe Mg Mn No Ni Se Zn Pp. viii + 39 21s. net Members of the Society for Analytical Chemistry are entitled to buy copies at the special Members’ price of 12s. 6d. provided they order direct from Remittances made o u t to “Society for Analytical Chemistry” must accompany Members’ orders The Editor The Analyst 14 Belgrave Square London S.W.1 Published for the Society for Analytical Chemistry by W. HEFFER AND SONS LTD. PETTY CURY CAMBRIDGE

ISSN:0037-9697    

DOI:10.1039/SA96401FX035

出版商:RSC    

年代:1964

数据来源: RSC

摘要:

Friday 1 1 th LEEDS Friday 1 1 th c A R D I FF THE SOCIETY FOR ANALYTICAL CHEMISTRY Forthcoming Meetings-coi2tinz4ed December Tuesday 8th MIDLANDS SECTIOK. F~II~MINGHAILI “Experience in U.S.A. on Boilers,” by D. H. Johns B.Sc. .%.1<.1.C. 4.Inst.F. “Principles o€ Chemical Control of High Pressure Boilers,” bj- E. C. Potter Haworth Lecture Theatre The Lniversity Birmingham 13 ; 6.30 p.m. BIOLOGICAL METHODS GKOUP A.G.M. folloxved by IXscussion Meeting. “Present Position with Regard to Microbiological Assay,” to be opened by “The Feathers,” Tudor Street London E.C.4; 6.30 p.m. NORTH OF ENGLAND SECTION and SPECIAL TECHNIQUES GROUP. “Some Aspects of Polarography,” by M. L. Kichardson A\.C.T. A. R.I.C. Great Northern Hotel Leeds; 7.30 p.m. WESTERN SECTION jointly 7uitJ~ the Cardiff and District Section of the Royal “Thin-Layer Chromatography,” by E.17. Truter B.Sc. Ph .D. .2.1I.C.S. University College Cardiff; 6.30 p.m. ATOMIC-ABSORPTION SPECTROSCOPY GROUP A.G.M. follo\ved l)!- a Discussion “Special Assemblies and Adaptation of Atomic-Absorption _%pparatus.” Meeting Room of the Chemical Society Hurlington House Imidon JV. 1 ; H.Sc. Ph.D. D.I.C. F.R.I.C. Thursday 10th 1.OXDOX E. C. Barton-Wright D.Sc. F.R.I.C. M.I.Bio1. Institute of Chemistry. Tuesday 15th LOXDON Meeting. 6.30 p.m. REPORTS OF THE ANALYTICAL METHODS COMMITTEE Reprinted from The Analyst Additives in Animal Feeding Stuffs Five Reports of the Additives in Animal Feeding Stuffs Sub- committee recently published in The Analyst are now available as individual reprints. They may be obtained direct from the Secretary The Society for Analytical Chemistry 14 Belgrave Square London S.W.1 (not through Trade Agents) price Is.6d. t o members of the Society and 2s. 6d. to non-members. A remittance made out t o “Society for Analytical Chemistry” MUST accompany every order. Part 1. Repovt of the Antibiotics Panel ’The Determination of Penicillin Chlortetracycline and Oxytetracycline in Diet Supplements and Compound Feeding Stuffs. Part 2. Kepovt of the Hovmoizes Panel The Determination of Stiboestrol and Hexoestrol in Compound Feeding Stuffs. Part 3 . Kepoid of Prophylactics Panel The Determination of Nitrofura7one in Compound Feeding Stuffs. Part 4. Repovt of the Vitamins (Watev Soluble) Panel The Determination of Water-soluble Vitamins in Compound Feeding Stuffs. Part 5 . Kepovt of the L’itamins ( F a t Soluble) Panel The Determination of Fat-soluble Vitamins in Diet Supplements and Conipound Feeding stuffs.THE SOCIETY FOR ANaLYTICAL CHEMISTRY Forthcoming Meetings November Thursday 19th COVENTRY Friday 20th CHESTER Tuesday 24th LONDOX Friday 27th GLASGOW Friday 27th SEWPO RT December IYednesday 2nd LAO N D 0 N Thursday 3rd GL ASGOW Friday 4th GLASGOW Monday 7th” LONDON nlInLAn.us SECTION. “Photometric Titrations,” by J . R. Headridge Ph.D. F.K.I.C. Lanchester College of Technology Priory Street Coventry ; 7 p.m. NORTH OF ENGLAND SECTION and SPECIAL TECHNIQUES GROUP. “High Kesolution Mass Spectrometry,” by IV. Sneddon B.Sc. Ph.D. The Blossoms Hotel Chester; 6 p.m. SPECIAL TECHNIQUES GROUP A.G.M. followed by Ordinary Meeting consisting of three short films. “Analysis by Mass.” “Infra-red Spectroscopy.” “Gas Chromatography.” Meeting Room of the Chemical Society Burlington House London \Y. 1 ; 7 p.m. SCOTTISH SECTION. “Some Aspects of Chemical Toxicological Xnalysis,” by H. IT. Strec,t hI.Sc. The University of Strathclyde Glasgow ; 7.15 p.m. \VESTERN SECTIOX jozntly with the Cardiff and District Section of the Royal “Recent Advances in Complexometric Analysis,” by T. S. IT‘est B.Sc n.Sc College of Advanced Technology Sewport; 6.30 p.m. Ph.D. M.I.Biol. F.K.I.C. Institute of Chemistry. F.R.I.C. SOCIETY Afternoon and Evening Meeting on “Solvent Extraction in Analytical Opening Lecture by Professor H. M. S . H. Irving M.-\. I).Phil. D.Sc . “Back Extraction by Addition of Organic Liquids,” by I\’. Milkow ski H.Sc. “Some Analytical Applications of Solvent Extraction in the Atomic Energy Industry,” by T.B. Pierce B.Sc. M.A. D.Phi1. “A New Method for the Determination of Traces of Some Surface Acti1.e Materials by Solvent Extraction and its Application to Continuous Analysis,” by G. R. E. C. Gregory. Chemistry. ” F.R.I.C. L.R.A.M. \Yellcome Building Euston Road London N.IV 1 ; 3 p.m. SCOTTISH SECTION jozntl-v with the Chemical Society the Royal Institute of The Ramsay Dinner. Central Hotel Glasgow; 7 p.m. SCOTTISH SECTION jointly with the Chemical Society the Royal Institute of “The Scientific Examination of Documents,” by Professor C. L. IYilson. The University of Strathclyde Glasgow ; 6 p.m. MICROCHEMICAL METHODS GROUP Discussion Meeting. “The Characterisation of Organic Compounds,” to be opened by D. At‘. Mathieson and L. C. Cross. “The Feathers,” Tudor Street Imndon E.C.4; 6.30 p.m. Chemistry and the Society of Chemical Industry. Chemistry and the Society of Chemical Industry. Ph.D. D.Sc. F.I.C.I. F.K.I.C. * Please note change of date from October 9th. Continued inside back cover PRINTED BY w. ~ E F F E R & SONS LTD.. CAMBRIDGE. ENGLAND.

ISSN:0037-9697    

DOI:10.1039/SA96401BX037

出版商:RSC    

年代:1964

数据来源: RSC

摘要:

November I964 Vol. I. No. I I PROCEEDINGS OF THE SOCIETY FOR ANALYTICAL CHEMISTRY Reports of Meetings ORDINARY MEETING AN Ordinary Meeting of the Society was held at 3 p.m. on Wednesday November 4th 1964 at the Wellcome Building Euston Road London N.W.1. The Chair was taken by the President Dr. D. C. Garratt Hon.M.P.S. F.R.I.C. The subject of the meeting was “Toxic Substances in Air” and the following papers were presented and discussed “The Significance of Maximum Permissible Concentrations,” by J. C. Gage R.Sc. Ph.D. F.R.I.C. ; “Air Sampling for Industrial Hygiene,” by S. G. Luxon F.K.I.C. ; “The Determination of Toxic Substances in Air by Gas Chromatography,” by S. Kaminsky B.Sc. A.R.C.S. D.I.C. ; “The Conductimetric Determination of Microgram Quantities of Phosphine in Air,” by S.Greenfield L.I.M. R. Perry B.Sc. and H. A. Mode B.Sc. A.R.I.C. ; “Radioactive Fall-out-Some Meteorological Aspects,” by D. H. Peirson B.Sc. F.Inst .P. ; “The Behaviour and Analysis of Radio-iodine at Verv Low Concentrations,” by A. E. J. Eggleton B.Sc. Ph.D. A.R.C.S. D.I.C. NORTH OF ENGLAND SECTIOK A JOINT Meeting of the Section with the Leeds University Union Chemical Society was held at 6.15 p.m. on Friday October 16th 1964 in the Chemical Lecture Theatre The University Leeds. The Chair was taken by the Chairman of the Section Mr. C. J. House B.Sc. A.R.C.S. F.R.I.C. A lecture on “Some Recent Developments in Analytical Techniques” was given by H. N. Wilson F.R.I.C. SCOTTISH SECTION AND MICROCHEMICAL METHODS GROCP A JOINT Meeting of the Scottish Section and the Microchemical Methods Group was held on Friday and Saturday September 25th and 26th 1964 at the University Aberdeen.The subject of the meeting was “Automatic Methods of Analysis.” The Chair was taken by the Chairman of the Scottish Section Dr. R. A. Chalmers at a scientific session at 6.45 p.m. on September 25th. The following papers were presented and discussed “Nomenclature,” bv T. €3. F. W. Fennell R.A. ; “Process Gas Chromatography,” by C. S. F. Pine B.Sc. Ph.D. A.R.C.S. ; “Automation in Clinical Chemistry,” by C. F. M. Rose F.K.I.C. ; “Differential Thermal Analysis,” by €3. D. Mitchell B.Sc. A.K.I.C. At 7.30 p.m. on September 26th a Discussion Meeting on aspects of automation that are of particular interest to micro-analysts was opened by the Chairman of the Microchemical Methods Group Mr. D. W. Wilson M.Sc.F.R.I.C. who also took the Chair. During the two-day meeting visits were paid to the Torry Research Station the Macaulay Institute for Soil Research the Chemistry Laboratories of the University and Chivas Rros. Distillery. MIDLANDS SECTION-ELlVELL AWARD PRESENTA4TIOS MEETING 1964 THE Elwell Award Presentation Meeting was held at 6.30 p.m. on Wednesday September 16th 1964 in the Haworth Lecture Theatre Chemistry Department The University Edgbaston Birmingham 15. The meeting was held under the joint Chairmanship of the T’ice-Chairman of the Section Mr. W. T. Elwell F.R.I.C. and the Honorary Secretarv of the Section Mr. M. L. Richardson A.R.I.C. A.C.T.(Birm.). The following papers were presented “The Determination of Olefinic Unsaturation on the Sub-micro Scale,” by B. Fleet M.Sc.A.R.I.C. ; “The Volumetric Determination of Aluminium with EDTA,” by M. A. Jenkins; “The Determination of Dialkyl and Diary1 Phosphites by High-frequencv Titration,” by D. G. Willetts L.R.I.C. (see summaries on p. 115). 113 114 REPORTS OF MEETINGS [Proc. Soc. Anal. C h e w The Elwell Award for the winning paper was presented to Mr. Fleet and the runner-up was Mr. Willetts. During the final judging a film “Black Monday,’’ was shown by courtesy of Imperial Chemical Industries Ltd. MIDLANDS SECTION A JOINT Meeting of the Midlands Section with the Birmingham and Midlands Section of the Royal Institute of Chemistry was held at 6.30 p.m. on Monday September 14th 1964 at the Haworth Lecture Theatre Chemistry Department The University Edgbaston Birmingham 15. The Chair was taken by the Vice-chairman of the Midlands Section Mr.IV. T. Elwell F.R.I.C. A lecture on “The Interpretation of Ionic Equilibria by Graphical Methods” was given by Professor H. Freiser and Professor Q. Fernando. A summary is printed on p. 124. MIDLAKDS SECTION SPECIAL TECHNIQUES GROUP AND THIN-LAYER CHROMATOGRAPHY GROUP A JOIST Meeting of the Midlands Section the Special Techniques Group (formerly Physical Methods Group) and the Thin-Layer Chromatography Group of the Society with the Birming- ham and Midlands Section of the Royal Institute of Chemistry was held at 1.30 p.m. on IVednesday October 14th 1964 at the Medical School The University Edgbaston Birming- ham 15. The subject of the meeting was “Thin-layer Chromatography” and it was divided into four Sessions. The Chairman of the first Session was Dr.E. V. Truter B.Sc. A.R.C.S. D.I.C. and the following papers were presented and discussed “Thin-layer Chromatography in Clinical Biochemistry,” by J. G. Lines MSc. Ph.D. A.R.I.C. ; “Exploitation of Thin-layer Chromatography in Plant Chemistry,” by E. J. Shellard B-Pharm. Ph.D. F.P.S. F.R.I.C. The Chair at the second Session was taken by Professor J. R. Squire M.A. M.D. F.R.C.P. at which the following Plenary Lecture was presented “Some New Techniques and Apparatus in the Field of Thin-layer Chromatography,” by Professor Dr. Egon Stahl. The Chairman of the third Session was Professor J. C. Robb B.Sc. Ph.D. D.Sc. F.R.I.C. and the following paper was presented and discussed “The Use of Thin-layer Chromatography in Biosynthetic Studies,” bv B. H. Davies B.Sc. Ph.D.A.R.I.C. The final Session was Chaired by Mr. W. H. Stephenson F.P.S. D.B.A. F.R.I.C. at which the following papers were presented and discussed “Recent Developments in Thin-layer Chromatography Equipment,’’ by R. P. Hirsch; “The Selection of Media for Thin-layer Chromatography,” by \-. C. Weaver B.Sc. A.R.C.S. (see summaries on p. 118). MIDLASDS SECTION AND ATOMIC-ABSORPTION SPECTROSCOPY GROUP A JOINT Meeting of the Midlands Section and the Atomic-Absorption Spectroscopy Group was held at 6.30 p.m. on Wednesday October 7th 1964 in the Grand Hotel Colmore Row Birmingham 3. The Chair was taken by the Chairman of the Atomic-Absorption Spectro- scopy Group Mr. ITT. T. Elwell F.K.I.C. The meeting took the form of a discussion on “Applications and Problems of Atomic- Absorption Spectroscopy” and was opened as follows “Applications and Problems in Gas Analyses,” by A.B. Densham; “The Determination of Lead in Gasoline and the Determina- tion of Silver,” by T. S. West B.Sc. D.Sc. F.R.I.C. ; “Applications and Problems in Agri- cultural Analyses by Atomic-Absorption Spectroscopy,” by T. R. Williams ; “The Determina- tion of Magnesium in Iron and Nickel Based Alloys,” by G. T. P. Humphreys and W. Rryson. MICROCHEMICAL METHODS GROUP THE forty-sixth London Discussion Meeting of the Group was held at 6.30 p.m. on Wednesday October 21st 1964 at “The Feathers” Tudor Street London E.C.4. The Chair was taken by the Chairman oE the Group Mr. D. W. Wilson M.Sc. F.R.I.C. A discussion on “The Determination of Phosphorus Applied to Organic Inorganic and Biological Materials” was opened by E. Q. Laws B.Sc. F.R.I.C.

ISSN:0037-9697    

DOI:10.1039/SA9640100113

出版商:RSC    

年代:1964

数据来源: RSC

摘要:

November 19641 ELWELL AWARD PRESEKTATION MEETING 115 Elwell Award Presentation Meeting The following are summaries of the papers presented by the finalists at the Elwell Award Presentation Meeting held on September 16th 1964 and reported in this issue of the Proceedings (p. 113). The Determination of Olefinic Unsaturation on the Sub-micro Scale BY B. FLEET (Chemistvy Depavtment The Univevsitji Edgbaston Bivminghawz 15) MR. FLEET said that for several years a programme of investigation had been in progress in the Chemistry Department to develop a scheme for the analysis of organic compounds (elemental and functional-group analysis) in which samples in the range of 40 to 80 pg were used. This was to anticipate the need for methods capable of analysing microscopic amounts of sample that would arise and was now in fact arising from the biochemical medical and related fields.This paper described the attempts to solve one of the few remaining problems the determination of olefinic unsaturation. The basis of the method was the addition of bromine monochloride to the double bond and subsequent iodimetric determination of the excess of reagent. The major problem encountered in the development of a method for determining olefinic unsaturation was the wide variation in the reactivity of this functional grouping in different molecules. This was reflected by the fact that there were now around 3000 published methods for the determination of this functional group. In this work two halogen-addition reagents had been compared firstly a solution of bromine in methanol containing an excess of potassium bromide (Kaufmann reagent) and secondly a solution of bromine monochloride in hydrochloric acid.Bromine monochloride had been found to be the most effective reagent as it was more reactive towards olefinic double bonds than elementary bromine because of its polar nature; whereas bromine mono- chloride added to the double bond in a,@ unsaturated acids elementary bromine under normal analytical conditions only added very slowly. The unreactive nature of many of the olefines analysed precluded the use of an instrumental method i.e. a coulometric generation of the halogen or even an instrumental method of end-point detection as the slow rate of addition caused the end-point to be diffuse. Halogen addition suffered from certain disadlrantages mainly the lack of specificitj- ; substitution at carbon atoms remote from the double bond occurred to varying degrees and eli- mination of hydrogen halide could also occur with certain compounds particularly high157 branched olefines and polymers.Interference from enols aromatic amines phenols etc. was also a complicating factor and a further disadvantage was that some of these reagents would not react with olefines in which the double bond was de-activated i.e. by conjugation to an electron-attracting group such as - COOEt - C=N or - F. In spite of these disadvantages halogen addition from an analytical point of view was very convenient and hence it was preferred to the more specific hydrogenation and per- oxidation reactions. The olefines investigated had been divided into four classes according to their reactivity- (i) cc unsaturated compounds (ii) isolated olefinic linkages (iii) conjugated dienes and (iv) vinyl-type (allytic) compounds and the rate of addition of a standard solution of bromine monochloride measured.The object of this study had been to investigate the effect of the various factors reagent concentration reaction time effect of catalysis etc. on the addition of bromine monochloride reagent to the different types of olefinic linkages. It had been found that whereas the less reactive olefines were unaffected by quite large excesses of bromine monochloride the more reactive olefines under similar conditions gave results that corresponded to 200 to 300 per cent. of the theoreti- cal value. With all of the samples analysed the composition and hence the double-bond 116 ELWELL AWARD PRESENTATION MEETIKG [Pvoc.SOC. Anal. Chem. content was accurately known. However when the sample to be analysed was of unknown composition there was a great possibility of high results being obtained owing to over- bromination. It had been decided therefore that for estimating the degree of unsaturation of unknown olefines a kinetic method must be applied. This consisted of allowing several samples containing varying mole ratios of bromine monochloride to double bond to react for a certain length of time and then determining the excess of reagent in the usualway. When the results of this experiment were plotted graphically (consumption of bromine monochloride against the ratio of bromine monochloride to sample) it was possible from the shape of the curve to deduce an approximate value for the degree of unsaturation.I t was then possible to obtain an accurate value for the degree of unsaturation by plotting a normal rate curve by using samples containing mole ratios of bromine monochloride to olefine corresponding to the position on the first graph where the initial steep portion levelled out. This kinetic procedure had been verified by applying it to the analysis of compounds of widely differing reactivity. The Volumetric Determination of Aluminium with EDTA BY M. A. JEKKISS (Reseavch Depavtment Impwial A4etals Itzdustries (liJ*nuch) Linzzted If-iffoi? Bi~iiziizgham 6 ) THE introduction of EDTA and metal-sensitive indicators Mr. Jenkins said had led to the development of comparatively rapid and simple analytical procedures for determining many elements including the determination of aluminium in copper-base alloys.The direct titration of aluminium with EDTA was impracticable because of the slow rate of formation of the complex and it was better to add an excess of EDTX and after the zolution had been boiled to ensure complete formation of the complex to back-titrate the EDTA with a solution of a suitable metal cation. EDTA reacted with many metals present in copper-base alloys and therefore separation or masking of these potential interferences was necessary. Many interferences had been overcome by the preliminary separation of aluminium as its benzoate succinate or as sodium aluminate. The degree of isolation was less important when masking agents such as tri- ethanolamine or sodium fluoride were used. These reagents formed strong complexes with aluminium and reacted with the aluminium - EDTX complex to liberate an equivalent amount of EDTA.The procedure which was first used by Sajo was outlined as follows- An excess of EDTA was added to a solution of the sample at pH 6 which was then boiled to form the complex between EDTA and aluminium. The excess of EDT-1 was titrated with a standard 0.05 M copper sulphate solution and PAN as indicator. Sodium fluoride was then added and the solution boiled to form the insoluble alumino-fluoride and an equivalent amount of EDTA was liberated. The released EDTA u’as titrated with the standard 0-05 11 copper sulphate solution to give a measure of the aluminium present. By using this method 0.25-g samples of aluminium bronze containing 5 to 10 per cent.of aluminium had been analysed with good results. S o interference had been found from alloying amounts of iron nickel manganese cobalt lead silver phosphorus and zinc. High results had been obtained when more than 0.1 per cent. of tin ivas present but this interference could be overcome by dissolving the sample in nitric acid and filtering off the metastannic acid formed. ,4 sample weight greater than 0.25 g was necessary when the aluminium content was less than 5 per cent. but the greater amount of copper then present modified the end-point. This situation was further aggravated because copper added as the back-titrant increased the blue colour of the solution so that the end-points before and after the addition of sodium fluoride were not identical. Thus when less than about 5 per cent.of aluminium was to he a d y s e d a preliminary separation was desirable and for aluminium contents belo;v I per cent. a separation was essential. Copper (and other interfering ions) could be removed by mercury-cathode electrolysis giving a colourless solution containing aluminium and manganese. Further greater sensitivity could be obtained by titrating the solution after electrolysis with a colourless metal ion rather than with copper. November 19641 ELWELL AWARD PRESENTATION MEETING 117 Samples containing 7 per cent. of aluminium had been titrated with zinc nitrate and xylenol orange indicator as described by Korbl and Pfibil but manganese interfered by causing the end-point to fade. PAN had been substituted for xylenol orange as originally described by Sajo but there had been no improvement in the end-point.Flaschka had shown that the very stable copper - PL4N complex which was an intense violet colour was formed with small amounts of copper when other cations were present in an excess of EDTA. Addition of copper ions to the solution before the titration with standard zinc solution had improved the end-point considerably. Use of complexing agents such as citric acid tartaric acid or potassium cyanide did not eliminate the interference due to manganese which had significance when more than 18 mg of this element was preFent. With this limitation however the final method which incorporated a mercury-cathode electrolysis and titration with 0-05 M zinc nitrate solution and a PL4N - copper indicator system could be applied to copper-base alloys containing from at least 0-1 up t o 10 per cent.of aluniinium. The standard deviation at these levels was 0.005 and 0-1 per cent. respectively. The Determination of Dialkyl and Diary1 Phosphites by High-frequency 'kitration BY D. G. WILLETTS (Research Uepnrtmeult A lbvight 6 Wilson (I'M&.) Lid. Oldbzw? Bivnzingham) MK. ~YILLETTS said that the methods available for the assa!- of dialkyl and diaryl phos- phites and for their determination in the corresponding trialkyl and triaryl phosphites either involved the determination of other acidic components preient or were time consuming. Further some methods were not applicable to diaryl or dichloroalkyl phosphites or both and chromatographic methods were inapplicable to volatile phosphites e.g. lower-alkyl phosphites. I t had therefore been thought that there was a need for an accurate rapid and specific method for determining dialkyl and diaryl phosphites.The proposed method was fairly rapid; a complete determination could be carried out in about an hour. I t was based upon the reaction of dialkyl and diaryl phosphites with carbon tetrachloride in the presence of an excess of ammonia or strong primary or secondary amines yielding chloroform. an aminophosphonate or a substituted aminophosphonate and the base h y drochloride- (RO),POH + CCl + 2R;NH -+ (RO),P=O + CHC1 + RiNH.HC1. I N R ; and the subsequent titration of the base hydrochloride with sodium methoxidc in methanol - benzene solution in the presence of pyridine- RAKH.HC1 + KaOMe -+ R:NH + NaCl + MeOH. A high-frequency titrimeter was used to detect the end-point and the hydrochloride was titrated in the reaction mixture prior separation being unnecessary.The volume of sodium methoxide solution used in the titration afforded a measure of the dialkyl or diaryl phosphite content of the sample. I t had been reported in the literature that no reaction occurred with trialkyl or triaryl phosphites and the results obtained confirmed this. Diethylamine had been used as the base and the titrant had been standardised against benzoic acid in methanolic solution with either methanolic phenolphthalein or methanolic o-cresolphthalein as indicator or alternatively by using a pH meter to detect the end-point. Initially attempts had been made to titrate the diethylamine hydrochloride in the reaction mixture by using either visual indicators or a pH meter to detect the end-point but these had been unsuccessful.The addition of pyridine to enhance the acidity of the diethylamine hydrochloride gave no improvement but under these conditions it had been found possible to detect the end-point of the titration with a high-frequency titrimeter. The amount of pyridine present during the titration and the amount of methanol present in the titrant had been fairly critical if good end-points and reproducible results were to be obtained. The presence of acidic impurities in the solvents used had given rise to high results. The error had been accounted for by carrying out a blank titration. This had been achieved by using a 118 ELWELL AWARD PRESENTATION MEETING [Proc. SOC. AnaZ. Chew. known weight of diethylamine hydrochloride in place of the sample under which conditions the blank value had been given by the difference between the actual titre and the theoretical titre equivalent to the added diethylamine hydrochloride.The high-frequency titrimeter had been used as a null-point instrument a Pye galvano- meter being used in place of the microammeter of the instrument to give a more accurate adjustment of the null point. It was essential that the lead connecting the instrument to the galvanometer should be screened and the screening connected to the earthed case of the instrument. The method had been successfully applied to the assay of dialkyl and diaryl phosphites and also to the determination of dialkyl and diaryl phosphites in the corresponding trialkyl or triaryl phosphites. It had been used for dimethyl- diethyl- dioctyl- and diphenylphosphites. Reproducible results had been obtained with dichloroalkyl phosphites but these results did not agree with results obtained by chromatographic methods of analysis. The lack of substantially pure dichloroalkyl phosphites at the present time made it impossible to state whether or not this method was applicable to dichloroalkyl phosphites.

ISSN:0037-9697    

DOI:10.1039/SA9640100115

出版商:RSC    

年代:1964

数据来源: RSC

摘要:

118 ELWELL AWARD PRESENTATION MEETING [Proc. SOC. AnaZ. Chew. Thin-lay er Chromatography The following are summaries of the papers presented at the Joint Meeting of the Midlands Section the Special Techniques Group and the Thin-Layer Chromatography Group of the Society held on October 14th 1964 and reported in this issue of the Proceedings (p. 114). The second of the four Sessions comprised the Plenary Lecture given by Professor Dr. Egon Stahl. Thin-layer Chromatography in Clinical Chemistry BY J. G. LINES (Biochemistry Department The Children’s Hospital Birmingham 16) DR. LINES said that thin-layer chromatography was particularly iduable in clinical chemistry because the amount of material available for analysis was frequently very limited and might even be inadequate for other forms of chromatography.There were alsosome applications of the technique in which its other major advantage namely the short time required for development might be of vital importance. Although thin-layer chromato- graphy had been applied to some of the more common chromatographic analyses undertaken in clinical biochemistry it would appear that further study was required before the technique superseded other forms of chromatography. However it would seem likely that as the tech- nique is more widely explored and its potential fully developed it would become a standard tool in clinical laboratories for all common analyses requiring the chromatographic separation of mixtures. At the present time thin-layer chromatography was being used in clinical chemistry mostly for research purposes. Although it had been found useful for a wide variety of investi- gations it had been of special value in the study of lipids.By the thin-laver technique very small amounts of total lipid extracts could be separated into each of the major lipid classes (e.g. tri- di- and mono-glycerides fatty acids phospholipids sterols and sterol esters) in a single dimension and by development with a suitable solvent in a second dimension the more comprehensive of these classes e.g. the phospholipids could be further subdivided into their components. In addition thin-layer chromatography could be used as a preparative pro- cedure to obtain a particular class of lipid for further analysis by some other techniques. Dr. Lines and his colleagues had found all these applications of thin-layer chromatography to be of value in the study of several metabolic problems.November 19641 THIN-LAYER CHROMATOGRAPHY 119 On the basis of the results of unidimensional separations of total lipid exti-acts from blood plasma or serum obtained under various physiological conditions he and 0. C. Forbes had been able to postulate the metabolic significance of hyperlipemia (in work to be published in Proceedings of the Association of Clinical Biochemists). This work started from the observa- tion that although monoglycerides had been present with all other classes of lipids in the intestinal lumen of rats and in the blood after a fat meal none had been found in the chyle collected simultaneously. The absence of monoglycerides from chyle was contrary to the expected result because the accepted route of fat absorption was into the chyle (A.C. Frazer Physiol. Rev. 1946 26 103). It appeared therefore that all absorbed monoglj-cerides were re-esterified into higher glycerides in the intestinal cells presumably through the enzymic pathway suggested by B. Clark and G. Hubscher (Biochinz. Biophys. Acta 1961,26 103) before being incorporated into chylomicra and discharged into the chyle. To explain the occurrence of monoglycerides in the blood plasma it had been postulated that they were formed bj- lipolysis of the triglyceride fraction of chylomicra during the clearing of these fat-bodies from the blood stream because fatty-acid release during this clearing process was a well recognised pheno- menon. The hypothesis accounting for monoglyceride production in blood had been sub- stantiated by both in vitro and iiz vivo experiments.In the former group of experiments samples of the lipemic plasma or chyle had been mixed with plasma from a heparinised rat; and in the latter heparin had been administered intravenously to a child with essential hyper- lipemia. In both instances the turbidity of the specimen had decreased (i.e. clearing of the lipemia occurred) and monoglycerides had been formed. The fatty acids produced during this lipolytic clearing process were normally bound immediately to the albumin fraction of the plasma proteins. Should the fatty acids not be bound the clearing factor which had been shown by E. D. Korn to be an cc-lipoprotein lipase (1. Biol. Cheiiz. 1955 215 15) is rapidly inhibited (B. S. Gordon E. Boyle R. K. Brown A. cherkes and C. B.Anfinsen Proc. SOC. Exp. Biol. N.Y. 1953,84,168; B. Shore Ibid. 1955 88 73). In nephrosis the plasma albumin might be reduced to less than 20 per cent. of its normal concentration and therefore it would seem probable that the hyperlipemia associated with this condition was due to inhibition of the clearing process because of accumulation in the plasma of fatty acids which would normally be bound to the albumin. Examination of the plasma lipids from a considerable number of nephrotic subjects showed monoglycerides to be markedly reduced or even completely absent. Further one patient with nephrosis (serum albumin 0.8 g per 100 ml) who had received a meal containing 40 g of butter fat did not have any detectable plasma monoglycerides at l+ 3 or 8 hours post-prandially although the degree of lipemia had increased during this period.I t had been concluded that the accumulation of chylomicra in the plasma of nephrotic subjects was probably due at least in part to the inhibition of the clearing factor. From theoretical considerations alone there were several possible causes of hyperlipemia. I t might be that the ingress of fat into the blood stream was increased the fat arising either from the diet from the fat depots including the liver or through carbohydrate metabolism. Alternatively hyperlipemia might be due to the impaired removal of chylomicra which would normally occur either by uptake of fat particles by the liver or by a lipolytic clearing process. From the evidence available at the present time it appeared that the latter cause of hyper- lipemia namely failure to clear chylomicra from the plasma by involvement of the lipoprotein lipase was the most important.This normal physiological process could be impaired for several possible reasons; either the enzyme might be deficient or it was either not released from its site of formation or was not activated; or alternatively normal action of the enzyme was inhibited because of the imperfect nature of the substrate the presence of an inhibitor in the plasma or due to a deficiency of the fatty-acid acceptor. I t might be tentatively con- cluded therefore that the metabolic significance of hyperlipemia was mainly representative of some fault in the lipolytic clearing of chylomicra from the blood stream. The validity of this hypothesis would have to be re-examined when more evidence was available on all the possible causes of this pathological condition.The value of thin-layer chromatography as a useful analytical technique had been demonstrated in this work for it had provided the most important information on which the postulate of the metabolic significance of hyperlipemia had been based. Indeed it could be stated that with the amounts of material available it probably would not have been possible to have detected the monoglycerides by any other chromatographic procedure. 120 ‘THIN-LAYER CHROMATOGRAPHY [Proc. SOC. Anal. Chem. The Exploitation of Thin-layer Chromatography in Plant Chemistry BY E. J. SHELLARD (Chelsea College of Science a i d Technology Manvesa Road Loxdon S . W . 3 ) DR. SHELLARD said that during the past four years examination of various species of hfitragyna had permitted him and his colleagues to note the presence of at least 24 alkaloids and to isolate 18 of them.Some of these had not previously been described. The fact that so many different alkaloids could be distinguished and isolated whereas previous workers on these plants had only obtained six was due to the high sensitivity of thin-layer chromato- graphy and the use of this technique as a preparative method. However it had been neces- sary to develop systems whereby mixtures of alkaloids in the plant extracts could be separated and distinguished with certainty. This problem arose acutely during the investigations of the leaves of the West African Mitragyna sti$ulosa (A. H. Beckett E. J. Shellard and A. N. Tackie J . Pharnz. Phannacol. 1963 15 158~) and Mitragyna ciliata two plants that were extremely difficult to distinguish from each other and which some authorities regarded a5 identical species.Four known alkaloids rhynchophylline jsorhynchophylline rotundifoline and isorotundifoline had been obtained (together with traces of mitraphylline from some samples) from hf. stipulosa. The same alkaloids had been found to be present in M . ciliata as indicated by melting-point infrared spectra and approximate RF value found by thin-layer chromatography on alumina with chloroform as solvent and on silica gel with ether as solvent. However it had been found by chance that the [.IL value of the “rhynchophylline” from 144. ciliata differed from that of the rhynchophylline from M . stipulosa (this agreed with the [a] value reported by previous workers).Further work had shown that this alkaloid was a second isomer of rhynchociline and was subsequently named ciliaphylline (A. H. Reckett E. J. Shellard and A. K. Tackie J . Plzarm. Pharmacol. 1963 15 1661.). Thus thin-layer chromatographic systems that would distinguish between these tNo alkaloids and any others that might have similar RF values to the already known alkaloids had been necessary. D. Ji’aldi K. Schnackerz and F. Munter ( J . Chromatog. 1961 6 61) had described a scheme that they claimed would permit them to identify any one of 54 named alkaloids. This had been based on RF values obtained with various systems and on colour reactions of the alkaloids. Dr. Shellard’s experience had been that no reliance could be placed on RF values of alkaloids separated from mixtures and no use could be made of colour reactions since all the alkaloids he had used were indoles or oxindoles.However he and his colleagues had devised a scheme based on that of Waldi Schnackerz and Munter details of which had been given by himself and J. D. Phillipson to the XXIII International Congress of Pharmaceutical Sciences (FIP) Munster 1963 (reported in the Proceedings published by Govi-Verlag G.m.b.H. Frankfurt-am-Main 1964 p. 209). By means of this scheme he and his colleagues had been able to distinguish 12 alkaloids rh ynchoph ylline isorh ynchoph ylline rot undif oline isoro tundif oline mi traph ylline and isomitraphylline speciofoline* ciliaphylline” rhynchociline mitragynine mitraciliatine* and an unnamed alkaloid from M . rotundifolia (E. J. Shellard and J . D.Phillipson Planta Medica 1964,12 27). Isomitraphylline had not been obtained from natural sources but by isomerisa- tion of mitraphylline according to the method of J. C. Seaton R. Tondeur and L. Marion (Canad. J . Chew. 1958,36,1031). Subsequently Phillipson had isolated an alkaloid that appeared to be identical with isomitraphylline (details to be published elsewhere) and the initial evidence for its presence in a plant had been its similarity to the synthetic isomitraphylline on all the thin- layer chromatographic systems. Of the alkaloids mentioned only mitragynine and mitra- ciliatine were indole alkaloids but recent work by Phillipson had revealed the presence of more indole alkaloids. Thin-layer chromatography would indicate that they could belong to two different isomeric groups but so far only the structure of mitragynine had been definitely elucidated.The mitragynine group had relatively high RF values whereas the mitraciliatine group had relatively low KF values though the alkaloids in each group followed the same pattern of movement with the various systems. It was thus an interesting speculation whether isomeric structure had some relationship with the absorption isotherms. One of the alkaloids in the mitragynine group separated from an impure sample of mitragynine could not easily be distinguished from mitragynine by any of the systems * Hitherto undescribed alkaloids. November 1964 THIN-LAYER CHROMATOGRAPHY 121 previously described and this had necessitated a new system alumina and chloroform - ben- zene (1 + 1) mixture in order to detect its presence.Thus this work continually demanded further exploitation of thin-layer chromatography in order to be certain that aZZ alkaloids present could be separated and identified. The lecturer expressed his thanks to Mr. J. I>. Phillipson for his work in connection with this contribution to the Symposium. Some New Techniques and Equipment for Thin-layer Chromatography BY EGON STAHL ( U9ziversity of Saarlandes Saavbvucken West GermanJl) PROFESSOR STAHL said that thin-layer chromatography on uniform smooth inorganic or organic layers had in the past 6 years developed into a valuable tool. Already 5 mono- graphs in book form had appeared. To increase the efficiency of the method further he and his colleagues had investigated the preparation of gradient layers and their use the influence of lower temperatures on the development of chromatograms and the direct qualitative and quantitative evaluation of chromatograms in the ultraviolet region.GRADIENT THIN-LA4\YER CHROMATOGRAPHY- After several years of experiments he and his colleagues had succeeded in developing a procedure for preparing gradient layers. It was based on their previous thin-layer spreading device. With the use of additional parts e.g. the “divider” and the mixing shaft the usual spreading device could be converted into a gradient mixer - spreader. The principle of the preparation of gradient layers was simple. When the divider was attached its diagonal partition divided the slurry compartment into two chambers. One of these could for example be filled with a suspension of acidic alumina and the other with a similar basic suspension.The bottom of the divider was then opened by tipping and the slurries were allowed to drop into the mixing compartments. The rotating discs prevented mixing along the shaft axis but ensured homogeneous mixing across this axis. Ry spreading this slurry on glass plates a layer was obtained that in the example they had chosen showed a continuous transition from “basic” to “acidic” alumina. On such layers the development of chromatograms could be carried out in three different directions. I t was now possible to combine the properties of two different sorbents and to establish for example which ratio gave the optimum separation. In this instance the direction of solvent flow was perpendicular to the gradient. On pH-gradient layers specific profiles were obtained for substances with basic or acidic functional groups.For development in the direction of the gradient layers with a transition from kieselguhr to silica gel had proved to be particularly useful. Gradient-layer chromatography opened up numerous new possibilities. The first publication about this technique had appeared in Che?~.ie-Ingenieur-Teclz.izik 1964 36 No. 5 and would appear in English in the international edition of Angewandte Ckzemie. A paper on gradient-layer chromatography of hydrophilic substances had been presented by P. J. Schorn at the International Symposium on Chromatography in Brussels September 1 964. LOW-TEMFERATURE THIN-LAYER CHROMATOGRAPHY- To carry out thin-layer chromatography at lower temperatures the usual Desaga S-chamber with the tubular trough was shielded with a transparent cooling-mantle connected to a cryostat.Refrigerant gases (e.g. monofluorodichloromethane) were used as developing solvents. In several instances he and his colleagues had succeeded in achieving a clean separation of complex mixtures by using low temperatures. Chromatography at low temperatures could also be applied to advantage to the separation of very unstable substances. DIRECT EVALUATION IN THE ~JLTRAVIOLET REGION- I t had appeared desirable to obtain ultraviolet-absorption and fluorescence spectra directly on the layer for the identification and quantitative evaluation of substances in the spots. In co-operation with C. Zeiss Oberkochen an attachment to the PMQ I1 spectro- photometer had been developed that allowed a direct evaluation.I t was now possible with this instrument to obtain an ultraviolet-absorption spectrum of substances on the chromato- gram directly by a reflectance technique. This instrument and the first results obtained with it had been discussed by H. Jork at the same Symposium. 122 THIN-LAYER CHROMATOGRAPHY [Proc. SOC. Anal. Chew. The Use of Thin-layer Chromatography in Biosynthetic Studies BY B. H. DAVIES (Department of Agricultuval Biochemistvy Uniueysity College of Wales -4 ber.tstwyth) DR. DAVIES said that many of the difficulties inherent in studies of the biosynthesis of natural products were due to the lability of intermediate compounds and often to the very small amounts of these compounds that occurred in nature. Thin-layer chromatography a technique characterised by its small scale and rapidity of operation was therefore ideally suited to work in this field.Its versatility in methods for the separation purification and identifica- tion of natural compounds had contributed in no small degree to many of the more recent advances in the field of terpene biosynthesis. Some of the best examples of the use of the technique in this field were concerned with the recent elucidation of certain stages in the biosynthesis of the tetraterpenes the carotenoid pigments. For the purposes of his paper he said that this biosynthesis could be divided conveniently into three stages- (a) Formation of the primary C, unit and its subsequent dehydrogenation to form a typical carotene e.g. lycopene (h) ring closure of the ends of the polyene chain to form cyclised carotenes e.g.p- carotene and (c) insertion of the oxygen function to form typical xanthophylls e.g. canthaxanthin spirilloxanthin. Phytoene rather than the C, analogue of squalene (lycopersene) had been established as the first tetraterpene formed in the biosynthesis. This had been largely the result of experiments based on the separation of squalene phytoene and lycopersene on thin adsorption layers. Lycopersene could not be detected in any of the carotenogenic organisms that had been examined. The removal of the layers from the supporting glass plates permitted the thin films to be passed under a radioactivity scanner when it was shown that whereas sterols carotenoids phytoene and squalene were highly radioactive after the incorporation either of labelled mevalonate into fungi or of labelled carbon dioxide into plants carrier lycopersene had acquired no radioactivity.Phytoene was then successively dehydrogenated through phytofluene r-carotene and neurosporene to lycopene. Thin-layer chromatographic studies had tended to rule out the possibility of ring closure at earlier stages in this sequence but the cyclisation of neurosporene to fl-zeacarotene had been shown in further studies by thin-layer chromatography of the recovery of the formation of cyclised carotenoids by Phyconz_vces blakesleeaizz,ts after a pre- liminary inhibition with diphenylamine. Diphenylamine also inhibited the formation of spirilloxant hin in Rlzodospirillwz YubYuwz. The removal of the inhibitor resulted in the recovery of xanthophyll biosynthesis; the sequence of this process had been convincingly demonstrated by the application of thin-layer chromato- graphy.The formation of keto-carotenoids such as canthaxanthin by the brine shrimp had recently been studied by feeding pure p-carotene and following its metabolism by thin-layer chromatographic methods. The instability of xanthophylls on adsorption layers could be overcome by using a reversed-phase partition system. The value of thin-layer chromatography to the current approach to the biosynthesis of other terpenes the quinones and sterols could not be overemphasised. In fact many of the key experiments as with those in the carotenoid field would have been much more difficult if not impossible without this simple and elegant technique. November 19641 THIbi-L-4YER CHROMATOGRAPHY Recent Developments in Thin-layer Chromatography Equipment 123 were based on one th a fifth possible RY R.P. HIRSCH (Camlab (Glass) L t d . Canzbvidge) MR. HIRSCH introduced his talk by describing slurry applicators that (1) stationary plate - moving spreader (2) moving plate - stationary spreader (3) stationary plate - spray applicator and of the four possible methods of obtaining layers- (4) application of dry powder on plate by rollers - spread layer w solution especially suitable for work with microscope slides i.e. simple dipping. He summarised that whereas Professor Stahl’s method of producing plates had been generally accepted initially as the best and only method of spreading layers on plates other ways had soon been considered by researchers and manufacturers of equipment. The adequate descriptions of these methods were enlarged upon by the display of slides.Next the preparative chromatography equipment of both Messrs. Shandon and Messrs. Desaga were reviewed emphasis being- given to the possible merits or demerits of 1-metre long plates as compared to-40-cm longpiates. Whereas Stahl et aZ. considered a layer of 1.5 mm a reasonable maximal practical layer hitherto preparative quantitative work had been carried out on layers of 4 and even 6 mm thickness. After this coverage was given to the range of ultraviolet lamps available; particular emphasis was laid on the popular two-wavelength Camag model on the one hand and the new Desaga seven-tube lamp (four ultraviolet and three daylight) and the Baird & Tatlock which offered like the Camag a choice of two wavelengths were introduced on the other.A more comprehensive section followed dealing with equipment for the detection of radioactive isotopes and the principles of procedure i.e. autoradiography scintillation counting and automatic scanning were compared to the Desaga Scanner specifically designed for the automatic evaluation of radioactive thin-layer chromatograms. His findings were tabulated iinder six respective headings- (2) Speed. (ii) Ease of operation. (iii) Was the layer of any use after evaluation? (in) Was it quantitative? ( n ) Could the contamination factor be ruled out? (vi) Did it detect tritium and cc-particle emitters? The speaker next covered the field of thin-layer electrophoresis and described both Dr. Kohn’s Mark I1 thin-layer electrophoretic apparatus and the more recent1.- introduced equipment from Messrs.Desaga. He regretted the sparseness of the literature dealing with this specific method. This topic was followed by a description of the BN chamber (devised by Professors Rrenner and Nietwisser of Basle University) with special reference to horizontal thin-layer chromatography as a variant to ascending-solvent chromatography in the conventional chamber and continuous thin-layer chromatography for the analysis of mixtures that could only be separated with difficulty. The chamber which worked on the “covered-plate” principle of construction contained a stainless-steel cooling-block that might be used to prevent the condensation of solvent vapour on the cover plate as well as a heating-block which facilitated the evaporation of the solvent after it had travelled over the run.Heating might be effected by steam warm water or an electrical heating element. The paper was concluded with a reference to low-temperature thin-layer chromato- graphy mention was made of the gradient spreader described earlier in the Symposium by Professor Stahl and finally the possible merits or demerits of the various types of adsorbents were briefly considered. 124 THIN-LAYER CHROMATOGRAPHY [Proc. SOC. Anal. Chem. The Selection of Media for Thin-layer Chromatography BY V. C. WEAVER ( W . R . Balsiofi Ltd. Spvingjield .Wills Maidenhead Kent) OKE important aspect of the expanding interest in thin-layer chromatography Mr. Weaver said was the resultant transfer of emphasis to the stationary phase. There was no universal adsorbent for thin-layer chromatography performance of a layer with respect to the solute and solvent was dependent on firstly separating the centres of solute zones and secondly keeping the zones compact.The former requirement that of separating solute-zone centres was dependent on the chemical nature of the mobile and stationary phases. Cellulose and silica gel were the most common stationary phases encountered in thin-layer chromatography. Cellulose was a polymeric material of molecular weight up to 500,CCO and was composed of anhydroglucose units. This was a strong hydrogen-bonding system that could donate and accept hydrogen atoms. Silica gel was a polymeric form of dehydrated silicic acid and presented two distinct types of interacting forces hydrogen bonding and induction interaction. Although cellulose and silica gel were both capable of a hydrogen-bonding mechanism the cellulose was more efficient.However only silica gel was effective for inducing molecular polarisation. This suggested that basically the solute should be compatible not only with the solvent but with the stationary phase as well. The second requirement of maintaining compact zones was dependent on minimising the molecular- and eddy-diffusion processes by enhancing the equilibrium kinetics between the two phases. This required a compromise in physical characteristics so that a thin-layer material must be designed for use with the most common solvent systems associated with it and the chromatographic system considered as a whole. I t was shown that cellulose powders were acceptable for use with polar solvents and silica gel with non-polar solvents.In addition the chemical nature of the materials made cellulose the choice for separating polar materials such as sugars and amino-acids whereas silicia gel could handle non-polar materials. Apart from the practical difficulties involved the systems were not ideal and with the growing range of thin- layer materials would no doubt be superseded. However sometimes an over-riding considera- tion such as the method of detection dictated the type of non-ideal system that should be used. In such instances the loading must be small if acceptable separations were to be obtained. Sature did not often supply mixtures containing equal amounts of the components so that minor constituents could be inadvertently overlooked if non-ideal systems were selected. ,Although cellulose and silica gel were the most common stationary phases alumina had been used extensively and for specific separations the use of polyamides cellulose acetate and ion-exchangers had been invoked to good effect. In the past stationary phases had been modified by impregnation.

ISSN:0037-9697    

DOI:10.1039/SA9640100118

出版商:RSC    

年代:1964

数据来源: RSC

摘要:

124 THIN-LAYER CHROMATOGRAPHY [Proc. SOC. Anal. Chem. Ionic Equilibria The following is a summary of a paper presented to a Joint Meeting of the Midlands Section of the Society with the Birmingham and Midlands Section of the Royal Institute of Chemistry held on September 14th 1964 and reported in this issue of Proceedings (p. 114). The Interpretation of Ionic Equilibria by Graphical Methods BY H. FREISER AND Q. FERNAXDO (Univevsity of 4vizona Tuscon Avizona 7Y.S.A .) PROFESSOR FREISER’S lecture dealt with a new approach to an old subject namely “A? Improved Method of Teaching Ionic Equilibrium Calculations with the Aid of Log Chart Transparencies.” This method an extension of the approach used in the recent text “Ionic Equilibria in ,4nalytical Chemistry” by H. Freiser and Q. Fernando (John Wley & Sons Inc.1963) which was the first text designed for undergraduates and presented the graphical November 19641 PAPERS ACCEPTED FOR PUBLICATION 125 methods of ionic equilibrium calculations involved a combined algebraic and graphical approach that greatly simplified the teaching of this important topic. The student was first introduced to the method in acid - base calculations ( i . ~ . pH cal- culations) in which the concentration of any species was shown to be the product of the total concentration of the component acid or base C and the appropriate fraction of this amount 01 that was present in the solution. A systematic approach to writing cc functions was developed in which the student learnt to identify each mathematical term in the expression with the concentration of a particular species in solution.Thus for a tribasic acid H,A the follow-ing terms were proportional to the concentrations of H,A H2A- HA2- and -4,- respectively [H+I3 K,[H+I2 K,K,[H+] and K,M,K3 and the proportionality constant was the reciprocal of the sum of these terms. At this point the logarithmic plot of cc as a function of pH was intro- duced because ( a ) since the pH was a logarithmic function it was convenient to express other concentrations in a similar manner (b) the logarithmic concentration of any species could be obtained by a simple addition of log cc and log C (constant €or any particular solution) and (c) these log - log graphs were simple linear functions except for limited regions where the pH was close to a pK value. A very useful teaching aid in the form of log cc z'cysus pH charts all printed to the same scale on 8 x 10-inch sheets of transparent plastic suitable for overhead projection (now commercially available) was demonstrated.Superimposition of one or several of these charts (HOAc H2C0, H2S H,PO or NH,) on a transparent base chart that had a ruled grid of -log C ueYsu.s pH made it possible to translate ct values readily into concentrations. Thus the description of the concentrations of all species of a mixture of acids and bases however complex as a function of pH might be made rapidly and simply in a niannei- that focused attention on the chemistry rather than on the arithmetic aspects of the situation. With the help of these charts pH calculations of even greater complexity could be carried out rigorously yet with ease. By using the proton-balance equation (alternatixlj- mass- and charge-balance equations might be used) to define the pH of a solution the transparent charts demonstrated clearly which terms in the equation were significant and I\-hich might be ignored and also led to a pH value evaluated to the nearest 0.1 unit. The simplified equation could if desired be solved by using appropriate cc expressions (also simplified with the aid of the charts) to give explicit algebraic solutions for the pH. By using this combined approach Professor Freiser had successfully taught second-year students regularly for the past several years and on an experimental basis first-year and even senior high-school students to solve problems that required a degree of understanding usuallj- expected only from far more advanced students.

ISSN:0037-9697    

DOI:10.1039/SA9640100124

出版商:RSC    

年代:1964

数据来源: RSC

摘要:

November 19641 PAPERS ACCEPTED FOR PUBLICATION 125 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. “Polarographic Determination of Residual Acrylonitrile and Styrene Monomers in Stj-rene - Acrylonitrile Copolymers,” by T. R. Crompton and D. Buckley. “Determination of Traces of Acrylonitrile Monomer in Liquid Extractants Used in Assessing the Suitability of Styrene - Acrylonitrile Copolymers as Food-packaging Materials,” by T. R. Crompton. “Determination of Traces of Selenium in Water by the Ring-oven Technique,” by S. I). Biswas and A. I(. Dey. “The Determination of Gold in Soil with Brilliant Green,” by R. E. Stanton and ,4. J. McDonald. “Quantitative Gas Chromatography of Aqueous Solutions Effect of \17ater on the Response of the Hydrogen-flame Ionisation Detector,” by J . S. Foster and J. W. Murfin. (‘Determination of Traces of Ethylenimine Monomer in Air Samples,” by T. R. Crompton. “The Microgram-scale Determination of Phosphorus in Organic Compounds,” by T. Sal- “The Identification and Assay of Mixtures of Antibiotics by Electrophoresis in Agar vage and J. P. Dixoii. Gel,” by J. W. Lightbown and P. de Rossi.

ISSN:0037-9697    

DOI:10.1039/SA9640100125

出版商:RSC    

年代:1964

数据来源: RSC

摘要:

126 [Proc. SOC. Anal. Chew. Changes in the Register of Members NEW MEMBERS ORDINARY MEMBERS Gordon Richard Anderson; Judah Arotsky B.Sc. Ph.D. (Southampton) A.R.I.C. ; Arthur Russell Bailey L.R.I.C. Dip.Chem. (Bradford) ; Peter Frode Jensen Bjmn B.Pharm. ; Francis Allan Booth; Phillippe Paul Chasseur L. C. 1ng.Chim. (Besanqon) ; Charles Keith David; Alan Charles Davis; Rudolf Eric Arnold Drey B.Sc. (Lond.) F.R.I.C. ; Thomas Dewsbury Frost ; Robert Deryck Hill B.Sc. Ph.D. (Manc.) A.R.1 .C. A. Inst .M.S.M. ; Charles Hiscock; E. June Maienthal B.S. (Missouri) ; Robert Leslie .John Morris M.A. (Cantab.) ; William Myron Nettle; Joyce Pentelow B.Sc. (Lond.) ; Iain Glen Lamond Sinclair B.Sc. (Edin.) Ph.D. (St. A4.); William Henry Stevens A.R.C.Sc. F.R.I.C. F.P.I. F.I.R.I.; Anthony Leslie Wilson B.Sc. (Lond.). JUNIOR MEMBERS George Ronald Keay L.R.I.C. ; David Schofield. DEATH We record with regret the death of James Muil Leitch.

ISSN:0037-9697    

DOI:10.1039/SA964010126b

出版商:RSC    

年代:1964

数据来源: RSC

摘要:

November 19641 PUBLICATIONS RECEIVED 127 Publications Received The publications listed below have been received by the Editor of The ,41inZ~ist in which journal Book Reviews will continue to appear. FLUORISE CHEMISTRY. Volume V. Edited by J . H. SIMONS. Pp. xvi + 505. Sen- York and NEW BIOCHEMICAL SEPARATIONS. Edited by A. T. JAMES and L. J . MORRIS. Pp. x + 424. London Toronto New York and Princeton New Jersey D. Van Sostrand Company Ltd. 1964. Price 84s. London Academic Press. 1964. Price 11 8s. ANALYSIS O F ANCIENT METALS. By EARLE R. CALEY. Pp. Xii + 173. Oxford Imldon Edinburgh Kew York Paris and Frankfurt Pergamon Press. Edition. Press. 1964. Price 42s. 1964. Price S0s. By H. A. FLASCHKA. EDT.4 TITRATIONS 4 ~ INTRODUCTION TO THEORY AND PRACTICE. Second Oxford London Edinburgh New York Paris and Frankfurt Pergamon Pp.144. ATLAS AKD TABLES FOR EMISSION SPECTROGRAPHIC ANALYSIS OF RARE EARTH ELEAIF STS. By CH. KEREKES. Edited by L. LANG. Tables pp. ii + 16 tables. Atlas 12 spectrographic charts. Oxford London Edinburgh New York Paris and Frankfurt Pergamon Press. 1964. Price 100s. Translated by K. J. IVIN. Pp. xiv + 277. London Methuen & Co. Ltd. 1964. Price 48s. in U.K. only. Pp. xii + 153. Amsterdam London and Xew York Elsevier Publishing Company. By K. S. CAWS M . L l . Dr. Phil. nat. F.II.1.C. Second Edition. Pp. x + 109. London Butterworth R Co. (Publishers) Ltd. 1964. I’rice 13s. 6d. PROGRESS IN XUCLEAR ENERGY. Series IX. ANALYTICAL CHEMISTRY. Volume 4 Part 1. Oxford London Edinburgh Sen- York Edited by WILLIAM 31. nluELLER GAX-IS MALLETT Proceedings of the Twelfth Annual Conference on Applicatzons of X-Raji ,-I nalJisis held ADVAXCES IS THE KINETICS OF HOMOGENEOUS GAS REACTIONS.By 2. G. SZARO. ICURIISA METHODS OF SUGAR ANALYSIS. Edited by H. C. S. DF. J~.HALLEY. 1964. Price 45s. AN ISTRODUCTIOK TO CHEMICAL XOMENCLATURE. Edited by CARL E. CROUTHAMEL. Paris and Frankfurt Pergamon Press. 1964. Price 30s. AND MARIE FAY. Pp. x + 662. New York Plenum Press. 1964. Price $22.50. Pp. iv + 72. ADVASCES I N X-RAY ANALYSIS. Volume 7. A%Lgust 7-9 1963. STATISTICAL METHOD I N BIOLOGICAL ASSAY. By D. J . FIXNEY nI.A. Sc.D F R.S. Second Edition. Pp. xx + 668. London Charles Griffin & Company Limited. 1961. Price 105s. ZONENSCHMELZEN. By Professor Dr. HERMAN SCHILDKNECHT. Pp. sii +- 226. \\-einheim l’erlag Chemie G.m.b.H. 1964. Price DM 26.THIX-LAYER CHROMATOGRAPHY. Edited by G. B. MARINI-BETT~LO. Pp. xii + 232. Amsterdam London and New York Elsevier Publishing Company. 1964. Price 65s. Proceedings ojthe Synzposiunz held at the Instituto Superiore di Sanita Ropne 2- 3 LIZav 1963. Prepared by the Committee on Specifications of the Food Chemicals Codex of the Food Protection Committee National Academy of Sciences - National liesearch Council. Pp. iii $- iv + 213-309 (loose leaf). Washington D.C. Sational -4cademy of Sciences - Xational Research Council. 1964. Subscription price for all parts including binder $25. Included in this are replacement pages for the original Pages iii and iv and 213-218. FOOD CHEMICALS CODEX. Part IV. THE BIOSYKTHESIS O F STEROIDS TERPENES AND ACETOGENIN5. f3y JOHN H. RICHARDS and JAMES B. HENDRICKSON. New York and London FY. A . Benjamin Inc. 1964. Price $20.35. Edited by IV. C. JOHNSON M.B.E. F.R.I.C. Fifth Edition. Pp. xii + 275. Chadwell Heath Essex Hopkin & JYilliams Ltd. 1964. Price 30s. Pp. xii + 416. ORGANIC REAGENTS FOR METALS AXD FOR CERTAIN KADICALS. Volume 2.

ISSN:0037-9697    

DOI:10.1039/SA9640100127

出版商:RSC    

年代:1964

数据来源: RSC

摘要:

128 NOTICES [Proc. SOC. Anal. Cheuut. Notices BRITISH STANDARDS INSTITUTION DRAFT SPECIFICATIONS A FEW copies of the following draft specifications issued for comment only are available to members of the Society and can be obtained from the Secretary Society for Analytical Chemistry 14 Relgrave Square London S.W.l. Draft Specifications prepared by Panel TLE/5/3/1-Methods of Analysis for Cathode D64/10210-Draft B.S. Methods for Analysis of Nickel for Use in Electronic Tubes D64/10211-Draft B.S. Methods for the Analysis of Nickel for Use in Electronic Part 21 Determination of Magnesium (Atomic-absorption Draft Specification prepared by Sub-committee M/55/1-Control of Conditioning D64/10542-Draft B.S. Specification for Laboratory Humidity Ovens (Injection Nickel. and Valves. Tubes and Valves.method). Atmospheres. Part 20 Spectrographic Method. Type) * THE PHARMACEUTICAL SOCIETY OF GREAT BRITA41S SYMPOSIUM ON IDENTIFICATION OF DRUGS AKD POISONS MARCH %TH 1965 A symposium on Identification of Drugs and Poisons organised by the Pharmaceutical Society of Great Britain will be held in London on Saturday March 20th 1965. Anyone wishing to be kept informed of arrangements for the symposium should contact The Pharma- ceutical Society of Great Britain 17 Bloomsbury Square London W.C.1. INTERNATIONAL SYMPOSIUM ON MICROCHEMICAL TECHNIQUES PENNSYLVANIA U.S.A. AUGUST 2hD-27TH 1965 THE Pennsylvania State University will conduct this 1965 Symposium at University Park Pennsylvania U.S.A. The programme is being organised by The American Microchemical Society (formerly the Metropolitan Microchemical Society) with the sponsorship of the International Union of Pure and Applied Chemistry.The technical sessions and social events will be similar to those of the 1961 Symposium held under the same auspices. Detailed information about registration and local arrangements will become available early in 1965. If you attended the 1961 Symposium such information will be sent to you routinely; otherwise the Organising Committee should be informed of your possible interest. Research papers directed toward small-scale operations techniques and methods in all phases of chemistry including clinica chemistry and biochemistry are required. Historical speculative or review papers will not be considered. Although the technical sessions even- tually organised will depend on the papers offered it is hoped to have sessions on the subjects listed below- (1) micro methods in structural elucidation ; (2) micro techniques in peptide studies; (3) clinical and forensic analysis ; (4) novel micro and ultramicro approaches in organic elemental analysis ; (5) micro techniques with high-energy materials ; (6) novel micro separation nethods ; ( 7 ) inorganic micro-analysis and trace analvsis ; (8) micro methods in air- and water-pollution studies; (9) determination of physical properties with small samples ; (10) education for instrumentation ; (1 1) general papers.Fuller details of the Symposium may be obtained from Mr. Howard Francis jun. Vice- Chairman International Symposium on Microchemical Techniques-1965 c/o Pennsalt Chemicals Corp. 900 First Ave. King of Prussia Pennsylvania U.S.A. or from Mrs. D. Kutterworth L.R .I .C. National Chemical Laboratory Teddington Middleses.

ISSN:0037-9697    

DOI:10.1039/SA9640100128

出版商:RSC    

年代:1964

数据来源: RSC