摘要:

Proceedings of the Society for Analytical Chemistry CONTENTS Reports of Meetings . . .. “Statistics and Analysis” . . “Particle-size Analysis” . . “Analysis of Drugs” . . . . Membership changes . . .. Papers accepted for The Analyst Publications Received . . I . Notices .. .. .. .. Forthcoming Meeting . . .. Proc. SOC. Analyt. Chem. Vol. 3 No. 6 Pages 95-104 95 96 97 I00 I02 I02 I03 104 I04 June 1966 Val. 3 No. 6 June 1966 PROCEEDINGS OF THE SOCIETY FOR ANALYTICAL CHEMISTRY President of the Society A. A. Smales O.B.E. Hon. Secretary of the Society S. A. Price Hon. 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 BELgravir 3258 Editor J. B. Attrill Proceedings is 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 t o “Society for Analytical Chemistry” MUST accompany orders The Determination of Sterols Society for Analytical Chemistry Monograph No. 2 -+- This Monograph contains six papers on various aspects of the determination of sterols by colorimetric and chromato- graphic methods applicable in many fields Available ONLY from The Editor “The Analyst,” 14 Belgrave Square London S.W. I (Not through Trade Agents) Price 15s. or US. $2.00 Post free A remittance made out t o “Society for Analytical Chemistry’’ should accompany every order. Members of the Society may purchase copies a t the special price of 5s. post free.

ISSN:0037-9697    

DOI:10.1039/SA96603FX019

出版商:RSC    

年代:1966

数据来源: RSC

摘要:

June 1966 PROCEEDINGS OF THE SQCIETY FOR ANALYTICAL CHEMISTRY Vol. 3 No. 6 Reports of Meetings NORTH OF ENGLAND SECTION AN Ordinary Meeting of the Section was held at 2.30 p.m. on Saturday April 23rd 1966 at the Old Nag’s Head Hotel Lloyd Street Manchester. The Chair was taken by the Vice- Chairman of the Section Dr. W. Cule Davies F.R.I.C. The following paper was presented and discussed “X-ray Fluorescence Analysis,” by R. Twemlow A.R.I.C. A JOINT Meeting of the Section with the North Lancashire Section of the Royal Institute of Chemistry was held at 7.30 p.m. on Friday May 6th 1966 at the Harris Technical College Preston. The Chair was taken by the Chairman of the Section Mr. J. F. Clark M.Sc. A.R.C.S. D.I.C. F.R.I.C. F.R.S.H. The following paper was presented and discussed “Rapid Screening Methods for Drugs in Body Fluids,” by M.S. Moss M.Sc. F.R.I.C. SCOTTISH SECTION and MICROCHEMICAL METHODS GROUP A JOINT Meeting of the Scottish Section and the Microchemical Methods Group was held from Friday to Sunday April 15th to 17th 1966 in the Chemistry Department The Univer- sity Edinburgh. A t the morning session on April 15th the Chair was taken by the Chairman of the Micro- chemical Methods Group Mr. R. Goulden F.R.I.C. and the following papers were presented and discussed “Analytical Applications of the Heteropoly Acids,” by R. A. Chalmers BSc. Ph.D. F.R.I.C. ; “Organic Trace Analysis by Fluorescence or Phosphorescence Measure- ments,” by C. A. Parker D.Sc. Ph.D. F.R.I.C. ; “The Precipitation and Determination of the Nitrate Ion,” by W. I. Stephen B.Sc. Ph.D. F.R.I.C.At the afternoon session on April 16th the Chair was taken by the Chairman of the Scottish Section Mr. J. K. McLellan M.A. B.Sc. F.R.I.C. and the following papers were presented and discussed “The Determination of Light Elements by Nuclear Techniques,” by T. B. Pierce B.Sc. M.A. D.Phi1.; “The Separation and Determination of Very Low Levels of Boron in Meteorites and Tektites,” by A. A. Mills B.Sc. Ph.D. ; “Problems Associated with the Determination of Fluorine especially in Biological Materials,” by R. J. Hall M.I.Biol. F.I.M.L.T. ; “The Determination of Phos- phorus,” by G. F. Kirkbright B.Sc. Ph.D. On the evening of April 16th a discussion on “The Determination of Sulphur and Halogens’’ was introduced by G. Ingram M.Sc. A.R.I.C. The meeting included a visit to the Links Distillery of Melrose Drovers Ltd.a tour of the Laboratories of the Chemistry Department University of Edinburgh and a coach trip to the Trossachs. The subject of the meeting was “The Determination of Non-metals.” THERMAL ANALYSIS GROUP AN Ordinary Meeting of the Group was held on Thursday and Friday April 21st and 22nd 1966 at the Royal College of Advanced Technology Salford. The Chair was taken by the Chairman of the Group Dr. R. C. Mackenzie F.R.I.C. F.G.S. F.R.S.E. The subject of the meeting was “Characterisation of Residues after Thermal Treatment.” On the afternoon of April 21st a visit was paid to the Research Laboratories of Pilkington Bros. Ltd. Lathom. At the morning session on April 22nd the following papers were presented and discussed “Modern Aspects of Dehydration and Decomposition of Mineral Silicates,” by A. A. Hodgson ; “Physical and Chemical Methods of Characterising Silicas,” by J. A. Hockey; “Differential Thermal Analysis of Edible Fats,” by D. P. J. Moran; “A Method of Thermal Analysis by Measurement of the Electrical Conductivity of Polymers During Carbonisation,” by M. I. Pope. 95

ISSN:0037-9697    

DOI:10.1039/SA9660300095

出版商:RSC    

年代:1966

数据来源: RSC

摘要:

96 STATISTICS AND ANALYSIS [Proc. SOC. Analyt. Chem. Statistics and Analysis The following is a summary of the paper presented at the Joint Meeting of the Midlands Section with the East Midlands Section of the Royal Institute of Chemistry and the Chemical Society of the University of Leicester held on February lst 1966 and reported in the March issue of Proceedings (p. 39). Statistics and the Design of Analytical Experiments BY F. DOWNTON MR. DOWNTON said that most books on the design of statistical experiments distinguished between absolute experiments leading to pure scientific knowledge and comparative experi- ments leading to some kind of decision. In the “exact” sciences it was usual to think of experimentation in terms of absolute experiments even although outside the research labora- tories most “exact” scientists were working in an environment that was not so readily con- trollable as the laboratory and were performing experiments that were part of some decision process.In a relatively uncontrolled environment statistical ideas were often not merely a convenient addition to a deterministic problem but an intrinsic part of the problem itself. Mr. Downton illustrated this by considering the behaviour of a simple chemical reaction. For the reaction A + B + C + D where A and B were in solution and C was precipitated out of solution a knowledge of the equivalent weights a b c d enabled the theoretical yield of C to be calculated. In practice the true yield was lower than C for a variety of reasons both chemical (e.g. solubility of C ) and statistical. If for example the amounts of A and B were not exactly a and b but were subject to errors with standard deviation o1 and a, respectively the actual yield of C (neglecting all other causes of depression of yield and (Department of Mathenzatical Statistics The University Edgbaston Birmingham 15) assuming Gaussian distribution of errors) would be c [ 1 - 2/ (Ol2Ia2 -k / ) (A Muir 2T ”‘I and F.Downton AppZ. Statist. 1953 2 30). That both chemical and statistical factors affected the process in a similar way meant that neither could be neglected in considering the yield of such a process. If it was required to increase the yield costs (whether of for example by using an excess of A over B to reduce loss through solubility or of operating a control system to reduce random errors in the amounts of A and B used) also needed to be taken into account.The aim of the experiment was to yield information in the presence of random errors and the purpose of the experimental planning was to obtain as much information as possible at as little cost as possible. This could not be achieved unless the chemical statistical and economic aspects of the experiment were treated as an integrated whole and the purpose of the experi- ment was fairly exactly specified. Mr. Downton summarised the requirements of a good experiment there should be an absence of systematic error; the experiment should have a satisfactory range of validity for its purpose; and it should result in sufficient precision. Systematic errors could arise in many ways. For example a comparison of the chlorine content of two different polymers by using two different analytical techniques could give rise to systematic error if one technique were always used for the determination with one polymer and the other technique always used for the other polymer.A randomisation pro- cedure for allocating techniques to polymers could eliminate such a type of error. Alterna- tively systematic errors might sometimes arise from random errors (e.g. the reaction A + B -+ C + 0) or because of faulty analysis. Where the results of experiments were to be used for predictive purposes or as part of some decision process it was important that they should be relevant to the region of prediction or decision. This was not merely that experiments performed at one temperature were not necessarily relevant to another temperature.Thistlethwaite (Analyst 1947 72 531) had investigated the precipitation of ammonium phosphomolybdate under a variety of con- ditions altering one factor at a time while maintaining others constant. A more effective method for determining the effect of these factors might well have been the use of a factorial experiment (0. L. Davies “The Design and Analysis of Industrial Experiments,” Oliver and Boyd London 1954 p. 258). Any experiment subject to random errors was analogous to this example. June 19661 PARTICLE-SIZE ANALYSIS 97 In the presence of random error no certainty could be attached to the result of an experi- ment. The precision achieved depended upon the intrinsic variability of the experimental material and techniques and on the size and design of the experiment. The cost of improving precision by increasing experimentation as against refining experimental techniques needed to be considered. Sometimes it was possible in simple cases to experiment sequentially until sufficient precision had been achieved.

ISSN:0037-9697    

DOI:10.1039/SA9660300096

出版商:RSC    

年代:1966

数据来源: RSC

摘要:

June 19661 PARTICLE-SIZE ANALYSIS 97 Particle-size Analysis The following are summaries of papers presented at an Ordinary Meeting of the Particle Size Analysis Group held on February 17th 1966 and reported in the April issue of Proceedings (p. 51). The Determination of Surface Area of Fine Particles BY N. G. STANLEY-WOOD (Bradford Institute of Technology Bradford Yorks.) MR. STANLEY-WOOD said that in many industries increasing emphasis was being placed on the size distribution and surface area of powders. Surface area could be determined directly or by calculation from size-distribution data. The direct methods available were liquid adsorption gas adsorption and permeametry. The adsorption of liquids usually fatty acids or dyes was not considered an acceptable method as the surface coverage was incomplete.Two methods were available for surface determinations by gas adsorption. One was the volumetric adsorption method in which a low pressure and a low temperature were used This conventional static method had been well tested and generally accepted as a standard. It was however laborious costly in material and time consuming. The surface area was determined by a graphical plot of the Brunauer Emmett and Teller equation either in its original form ( J . Amer. Chem. Soc. 1938 60 309) or modified form (G. D. Halsey J . Chem. Phys. 1948 16 931; G. F. Hiittig Mh. Chem. 1948 78 177). An alternative means of evaluating surface area by using the same experimental results obtained from the conventional static gas-adsorption method was that of the relative method of Harkins and Jura ( J .Chem. Phys. 1943 11 431; J . Amer. Chem. Soc. 1944 66 1362). Use of this relative method did not necessitate the assumption of the molecular area of nitrogen at the temperature of liquid nitrogen as with the Brunauer Emmett and Teller determination. Comparison of the surface areas obtained from these two independent methods could be used to determine the precision of the surface-area determinations. The second method for adsorption of gases was that of continuous flow. This method which had first been proposed by Loebenstein and Deity ( J . Res. Natn. Bur. Stand. 1951,46 51) and then subsequently developed by Nelsen and Eggertsen (Analyt. Chem. 1958,30,1387) was based on the technique of gas chromatography. Determination of the surface area of fine particles was achieved by either a standard Brunauer Emmett and Teller or Harkins and Jura plot.The PIPo values were obtained from a number of different flow rates of a mixture of two gases one the absorbate and the other an inert non-adsorbent diluent. The volume adsorbed from the flowing mixture of gases was measured by the change in thermal conductivity of the gas mixture before and after it passed over a sample cooled in liquid nitrogen. The thermal conductivity cell or katharometer was connected to a pen recorder which traced out an area when the thermal conductivity increased or decreased. This area was calibrated with a known volume of adsorbate gas before the surface-area determination. Although the continuous flow method dispensed with low pressure low temperature and graphical interpretation of the results were still necessary the graphical analysis being more time-consuming than the experiment a1 technique.Permeametry was a simple rapid technique in which the external surface was easily determined. The theoretically derived equation was however extremely limited and rendered the technique acceptable only on a control basis. The method was further limited in that it only applied to coarse powders (d 2 10 p). As the ratio of pore size of a packed bed to mean free path of the gas decreased however gas diffusion played an increasingly more important part in the flow. 98 PARTICLE-SIZE ANALYSIS [Proc. SOC. Analyt. Chem. Advantage could be taken of this gas diffusion in the transient-flow technique of Barrer and Grove (Trans. Faraday SOC. 1951,47 826 837) in which flow was predominantly mole- cular and the viscous term neglected.In this technique the time taken to set up steady diffu- sion was indicative of the total surface area of powders as opposed to the external surface of permeametry. The apparatus and technique used were more simple than both the static and continuous gas-adsorption methods the surface-area determinations being carried out at room temperature with a moderately high vacuum. Comparison of surface areas obtained with this method were not in agreement with Brunauer Emmett and Teller or Harkin and Jura values. Further investigation into the method and values obtained was necessary before any significance could be claimed. Particle-size Analysis by Optical Microscope BY G. L. FAIRS* (Formerly with Imfievial Chemical Indztstries Ltd.Mond Division Engineering Department Cheshire) MR. FAIRS said that the basic principle of measuring particle size by optical microscope as laid down in British Standard 3406 Part 4 1963 was by visual observation of the projected areas of the particles concerned and by matching them against the areas of a series of circles on a graticule the diameters of the series being in a 2/2 progression. The graticule either formed part of the projection screen of a projection microscope or was mounted in the eyepiece of a bench microscope. This technique was subject to three types of error the first two being manipulative i.e. errors in matching the particles against the comparison circles and systematic i.e. errors in adjustment of the optical system and both of these could be easily reduced to insigni- ficant levels with experience.The third type of error was statistical and inherent in the method and was known as the “inevitable error of counting” and was dependent upon particle size and the number of particles counted. It was important therefore that the statistical accuracy of the count*should be controlled to a reasonable accuracy bearing in mind that unnecessarily high accuracies involved counting an enormous number of particles. A statistical method had been developed for particles in a 4 2 progression that reduced the number of particles to a minimum for any required accuracy and at the same time pre- served that accuracy throughout the size range of the sample under consideration The treatment varied somewhat according to whether the size analysis was to be as a weight or frequency basis the former being the more usual.In this instance the statistical accuracy depended mainly on the largest particles in the sample and could be calculated approximately from the equation- where a(Mq) = standard deviation expressed as a percentage of the total by weight Mq = percentage by weight in the given size range and nd = number of particles counted in the size range. In general where the classes were in a 4 2 progression it was found that about 10 per cent. by weight of the particles were in the top class. Under such conditions it would be necessary to examine sufficient areas of graticule to ensure a count of 25 such particles in order to reduce the standard deviation to &2 per cent. In order to preserve this accuracy throughout the size analysis it was necessary that the following equation should be satisfied- where d = volume mean diameter of the size range n = number of particles counted in size range “d,” a = area of graticule rectangle at magnification at which caunt was made K = number of areas examined and Q = control factor.* Present address Thornton House Bear Street Hay on Wye via Hereford. June 19661 PARTICLE-SIZE ANALYSIS 99 The control factor was worked out for the largest particles counted to give the desired accuracy (standard deviation) and sufficient particles were counted in all other classes to ensure that each control factor was not greater than that for the largest particles. The numbers of particles so counted were equated to a common area and then multiplied by the appropriate volume factor d3 (see above) from which the weight distribution could be calculated.Full details of the mathematical derivation of the equations with a worked example of a size analysis were given in British Standard 3406 Part 4 1963. Similar considerations held for frequency distributions in which where o(Fl) = standard deviation expressed as a percentage of the total by frequency Fl = frequency of particles in a given size range !?bd = number of particles in a given size range and nt = total number of particles of all size ranges in the area examined. F,(100 - Fl) had a maximum value of 2500 for a size range containing 50 per cent. of the particles. It would be unlikely that any size range in a 4 2 progression would contain more than that; therefore for any value of nd Fl was greatest for the size ranges containing the largest proportion of particles.Thus assuming the area of slide examined gave sufficient accuracy for those size ranges it was adequate for the remainder and the same area could be used for all. The method held for all particles except those exhibiting extremes of shape but could be modified to deal with acicular and tabular particles. High quality optical equipment was essential when measuring particles of less than 10 p diameter. This was especially important with objectives and substage condensers. The Abbk condenser commonly supplied with microscopes was useless for this sort of work. The statistical accuracy of the method depended upon the examination of a uniformly dispersed sample and methods of achieving this both with suspensions of solids in liquids and mists were given in the British standard mentioned above which was based on a method that was originally developed by G.L. Fairs ( J . Roy. Microsoc. Soc. 1951 71 209). Size Analysis with the Coulter Counter Comparison with Sedimentation and Surf ace - area Measurements BY M. J. THORNTON MR. THORNTON said that the Coulter Counter had now superseded sedimentation methods for routine size analysis in his laboratory. Examples were given showing the results obtained by the two methods on two water-insoluble drugs vix. phenothiazine a veterinary anthel- mintic and griseofulvin an oral antibiotic for treatment of fungous infections in man. The recent issue of the British Veterinary Codex contained a method for the size analysis of phenothiazine by means of the Andreasen Pipette.The technique involved sampling a sedimenting column of suspension from a fixed depth below the surface at times calculated by means of Stokes' equation to give percentages by weight corresponding to particles of less than 30 p and less than 10 p diameter. This was a satisfactory technique but took practically a whole day to complete whereas with the Coulter Counter once the routine had been estab- lished a complete size analysis could be supplied in less than 1 hour. Complete data on the various Coulter Counter models was available from the manu- facturers and descriptions of apparatus and techniques had been published in scientific journals the most recent being that in the January 1966 issue of Manufacturing Chemist. He therefore gave only a brief description. The method consisted essentially in amplifying and counting pulses in an electronic circuit caused by the passage of solid particles through a cylindrical hole (50 p diameter with the instrument used) in the side of a glass tube.The particles caused changes in the electrical conductance of the electrolyte usually dilute sodium chloride solution proportional to their volume and were thus counted and sized. (Imperial Chemical Industries Ltd. Phawzaceutical Division Macclesfield Cheshire) 100 ANALYSIS OF DRUGS [PYOC. SOC. Analyt. Chem. The Coulter Counter was calibrated by counting spherical latex spheres of known particle size supplied for the purpose by the Dow Corning Company. Carrying out such a procedure enabled a value to be given to a constant k which when multiplied by the values derived by the makers from the design of the instrument for different sensitivity settings (which corres- ponded to different size ranges) gave an absolute value of particle diameter for each range.It was obvious therefore that the value assigned to this constant k was of primary impor- tance particularly when the results of a size analysis obtained by means of the Coulter Counter were compared with those obtained on the same material by other means. In the lecturer’s experience the value of k obtained by direct calculation from the latex spheres did not give results similar to those obtained by means of the Andreasen Pipette. However a comparatively small alteration to the value brought the whole distribution into line so that for continuity of recording results the modified k value was used.If the material under test was in the form of a dry powder further comparison could be made by means of surface-area measurements as the results of a particle-size count could be transposed to give a theoretical surface-area figure. Direct measurements of surface area were made by means of an air-permeability apparatus. The technique involved compressing the powder into a plug of known dimensions held in a cylindrical container and measuring the time taken for a given volume of air under a known pressure to flow through it. This was a simple and reproducible method of producing a figure viz. the specific surface area which served to characterise a powder although it did not of course give any idea of the spread of particle size within the sample. However if the same powder was suspended in a suitable dispersion mixture and counted by means of the Coulter Counter it was usually found that the distribution was logarithmic normal whatever value of k was used so that by means of statistical principles a surface area could readily be calculated. When this was done reasonable agreement was found between results obtained with the Andreasen Pipette the Coulter Counter with the amended k value and air-permeability surf ace-area apparatus.

ISSN:0037-9697    

DOI:10.1039/SA9660300097

出版商:RSC    

年代:1966

数据来源: RSC

摘要:

100 ANALYSIS OF DRUGS [Proc. SOC. Analyt. Chem. Analysis of Drugs The following are summaries of papers presented at the Joint Meeting of the Midlands Section with the Forensic Society and the East Midlands Section of the Royal Institute of Chemistry held on March Sth 1966 and reported in the May issue of Proceedings (p. 69). New Applications in Pharmaceutical Analysis BY S. G. E. STEVENS (Smith Kline afid French Laboratories Ltd. Mundells Welwyn Garden City Herts.) MR. STEVENS said that with the current interest in drug purity it was not surprising that the newer techniques in pharmaceutical analysis had shown a tendency towards greater specificity and sensitivity. While many papers had appeared in which thin-layer chromatography was used as the basic method only a few fully merited inclusion under the title of new applications.One of the more important was that by Professor Stahl who described a modified spreader capable of providing a thin-layer plate in which the pH could be graded across the plate. It offered the additional advantage that the solid adsorptive medium could also be formed on a gradient basis from two different media. He had been able to demonstrate the value of such techniques by the separation of a number of belladonna alkaloids. Warren in a more recent issue of the Journal of Chromatograjhhy had described a simpler and cheaper form of the gradient spreader. An interesting development following a thin-layer separation was that reported by Boardman and Warren at the Nottingham Conference of the Society for Analytical Chemistry where acidic and basic compounds chromatographically separated could be conductimetrically titrated in Sit%.That there was still a place for paper chromatography was evidenced by the work of Reinking and Barnabeo. They used the technique in an assessment of the level of impurities with a colour extinction process. This process was based on the measurement of the sample dilution factor which was just necessary to inhibit the formation of a characteristic colour in the individual bands on horizontal circular paper. June 19661 ANALYSIS OF DRUGS 101 Evidence that gas - liquid chromatography could be usefully employed in pharmaceutical analysis was accumulating. This was illustrated by reference to work in the author’s labora- tories on the separation from grease-based ointments of camphor menthol methyl salicylate ethyl salicylate and amyl salicylate with diphenyl as an internal marker.One of the prob- lems of the gas - liquid chromatography method was the possibility of overlap and tailing when examining mixtures of related compounds. The use of derivatives to improve the resolution was exemplified by the use of the acetone complex with ephedrine and amphetamine compounds and the trimethyl silyl ethers in the testing of the methyl and ethyl esters of hydroxybenzoic acid. Polarography had so far failed to find general acceptance as a useful analytical tool in the study of drugs. The work of Porter on substituted phenothiazines and the corresponding sulphoxides requiring only small amounts of material would surely stimulate further interest in this approach as would the applications from the author’s laboratories on nitrofurans.A frequent criticism of non-aqueous titrimetric methods was their lack of specificity but this did not detract from their value in routine analytical control procedures and the recom- mended use of acetonitrile by Mainville and Chatten in the examination of groups of local anaesthetics sympat homimet ics antihistamines and phenot hiazines was a useful suggest ion. The original paper needed to be consulted for the specific details. An interesting application of neutron-activation analysis by Tuckerman and his colleagues caused attention to be focused on the levels of drug impurities some of which had not been previously reported. Prednisolone and calcium gluconate had been stated to contain up to 900 p.p.m. of bromine and this element had been detected in many of the drugs tested.The technique was obviously one for the specialist as it involved the use of a “spectrum splitting” technique designed to eliminate each element in turn. Substitution of proprietary products was not a serious problem at present in this country but to those with export interests it could be a nuisance. Attention had been drawn to the possible value of profile measurements as a rapid means of product identification especially when examining tablets. Examples were given of the importance of profile measurements of tablet angles and the surface characteristics and a series of photographs illustrated something of the potential of this approach which could save a considerable amount of analytical time when dealing with complicated formulations.Drug Analysis with Special Reference to Forensic Analysis BY E. G. C. CLARKE (Department of Physiology Royal Veterinavy College London N . W. 1) DR. CLARKE said that although the future of forensic toxicology might involve elaborate instrumental techniques at present perfectly adequate results could be obtained by the use of reasonably simple methods. The discipline was one that had its own particular difficulties- the utter irreplaceability of the test material the serious implications arising from any kind of poisoning and the necessity for any findings to stand up to cross examination in court. The task of the forensic chemist was made extremely difficult not only by the vast number of drugs now available but also by the fact that any unusual compound isolated from cadaveric material had to be identified with complete certainty before it could be decided whether its presence was significant or not.In a considerable proportion of the cases brought to the forensic laboratory there was no clue at all as to the nature of the poison and a general search had to be made. Some method of extraction and purification had to be chosen that would give a reasonable chance of extract- ing at least some of any drug that might be present. Once its identity had been established one could decide on the most suitable method for its extraction and determination and carry it out on a further aliquot of material. The speaker said that it was convenient to divide poisons from an analytical point of view into 5 classes volatile dialysable solvent-extractable metallic and miscellaneous.By far the largest number of what were commonly called drugs were to be found in the third of these categories and he proposed to devote the time to considering this group. 102 PAPERS ACCEPTED FOR PUBLICATION [Proc. SOC. AnaZyt. Chem. After preliminary treatment with alcohol ammonium sulphate or sodium tungstate to remove protein the aqueous extract was acidified and extracted with ether to remove acidic and neutral drugs and then made alkaline and extracted with chloroform to remove the bases ; conjugates and quarternary ammonium compounds remained in the aqueous phase and needed special treatment the former being broken down by boiling with dilute hydro- chloric acid or by treatment with glucuronidase the latter being obtained by evaporating to dryness and extracting with methanol.The acid - ether extract could be sub-divided by extracting it first with sodium bicarbonate solution to remove the strong acids (e.g. salicylic; fraction A) and then with sodium hydroxide solution to remove the weak acids (e.g. barbi- turates; fraction B) the neutral drugs (carbamates ureides etc. ; fraction C) remaining in the ether phase. The basic drugs (fraction D) could be sub-divided if so desired by first making the solution alkaline with sodium hydroxide solution and extracting with chloroform this giving the non-phenolic bases (fraction D1) and then by acidifying making alkaline with ammonia and extracting with chloroform - isopropanol to give the phenolic bases including morphine (fraction D2). Each fraction was then examined by some suitable system of paper or thin-layer chroma- tography.By considering the basic drugs (by far the largest class) as an example the residue from the alkaline - chloroform extract might be run on a paper chromatogram (citrate - butanol system) and the papers examined under ultraviolet light and subsequently sprayed with iodoplatinate and bromocresol green. Comparison of these results with tables of published data might suggest that the unknown was probably one of a dozen compounds. Further chromatograms could be run with these substances as controls. Finally the unknown could be eluted from the chromatogram spot and its identity finally established by ultraviolet spectrophotometry or by colour and crystal tests. If more sophisticated equipment was available it could of course be used at this point.The R value could then be determined. This should narrow the choice still further. Changes in the Register of Members DEATHS WE record with regret the deaths of Thomas Mann Harold Lawson Webster. 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. “The Determination of Vitamin D in the Presence of Vitamin A,” by F. Said M. K. “A Chemiluminescence Method for Determining Ozone,” by D. Bersis and E. Vassiliou. “Iodimetric Analysis of Organo-aluminium Compounds,” by T. R. Crompton. “An Ultraviolet Spectrophotometric Method for the Determination of 3-Amino-lH-1,2,4- “The Detection of Cashew-nut Shell Liquid by Thin-layer Chromatography,” by T. W. “Determination of Trace Amounts of Copper in Niobium and Tantalum by Atomic- “The Determination of Total Available Oxygen in Di-tertiary Butyl Peroxide,” by D.B. “The Colorimetric Determination of Hydroxamic acids,” by R. Nery. “Separation and Determination of Small Amounts of Tin,” by E. J. Newman and P. D. Salah and P. Girgis. Triazole,” by B. D. Wills. Hammonds. absorption Spectroscopy,” by G. F. Kirkbright M. K. Peters and T. s. West. Adams. Jones. June 19661 PUBLICATIONS RECEIVED 103 “Analytical Primary Standards for Plutonium Quantitative Separation of Plutonium from Dicaesium Plutonium Hexachloride,” by F. J. Miner. “Polarographic Determination of 0.01 to 0.10 per cent. of Bismuth in Lead,” by J. Bassett and J. C. H. Jones. “The Oxidation of Hydroxylamine in Sodium Hydroxide in the Presence of Copper(I1) ,” by J.H. Anderson. “An Examination of Some of the Factors Affecting the Determination of Carbon Dioxide by Non-aqueous Titrimetry,” by P. Braid J. A. Hunter W. H. S. Massie J. D. Nicholson and B. E. Pearce. “A Simple Colorimetric Finish for the Johnson - Nishita Micro-distillation of Sulphur,’’ by G. A. Dean. “A Simple Multipurpose Titrimeter,” by W. Jennison and M. L. Clark. “Comparison of Particle-size Analysis Data obtained by using a Centrifugal Photosedi- mentometer with those obtained from Centrifugal Pipette Equipment,” by M. W. G. Burt and B. H. Kaye. “The Determination of Ethanolamine and Serine in Phospholipids,” by A. J. De Koning. “Semi-quantitative Determination of Organo-phosphorus Insecticides by using the Ring- oven Technique with Preliminary Thin-layer Chromatography,” by I. Pej kovic- Tadic S. L. J. Vitorovic M. B. Celap and T. J. Janjic. “Determination of Total Sulphur in Soil and Plant Material,” by I. A. Chaudhry and A. H. Cornfield.

ISSN:0037-9697    

DOI:10.1039/SA9660300100

出版商:RSC    

年代:1966

数据来源: RSC

摘要:

June 19661 PUBLICATIONS RECEIVED 103 Publications Received The publications listed below have been received by the Editor of The Analyst in which journal Book Reviews will continue to appear. TECHNIQUES OF OSCILLOGRAPHIC POLAROGRAPHY. By ROBERT KALVODA. Second Edition. Pp. 214. Amsterdam London and New York Elsevier Publishing Company. 1965. Price 60s. Pp. xii + 508. Published for the Nobel Foundation. NOBEL LECTURES CHEMISTRY 1922-1941. Amsterdam London and New York Elsevier Publishing Company. Pp. s + 373. 1966. Price 30s. 1966. Price 160s. AN APPROACH TO CHEMICAL ANALYSIS. ITS DEVELOPMENT AND PRACTICE. By H. N. WILSON. Oxford London Edinburgh New York Paris and Frankfurt Pergamon Press. DYNAMICS OF CHROMATOGRAPHY. PART I PRINCIPLES AND THEORY. Edited by J. CALVIN GIDDINGS. Pp. xii + 323. London Edward Arnold (Publishers) Ltd. New York Marcel Dekker Inc. 1965. Price 90s. REACTION MECHANISMS IN ORGANIC CHEMISTRY. By BLANCA TCHOUBAR. Second Edition. Pp. 197. London Iliffe Books Ltd. New York American Elsevier Publishing Inc. 1966. Price 45s. SOIL PHOSPHORUS Proceedings of a Conference organized by the Soil Chemists of the National Agricultural Advisory Service. October 4th to Sth 1962. Ministry of Agriculture Fisheries and Food Technical Bulletin No. 13. Pp. vi + 159. 1965. Price 37s. 6d. Proceedings of a Conference held in Paris September 1964. Edited by W. L. MEAD. Pp. xviii + 1064. London The Institute of Petroleum. Amsterdam The Elsevier Publishing Company 1966. Price 140s. ADVANCES IN MASS SPECTROMETRY. Volume 3.

ISSN:0037-9697    

DOI:10.1039/SA9660300103

出版商:RSC    

年代:1966

数据来源: RSC

摘要:

THE SOCIETY FOR ANALYTICAL CHEMISTRY Forthcoming Meeting July MICROCHEMICAL and AUTOMATIC METHODS GROUPS Demonstration Meeting Lectures and working demonstrations by manufacturers of- Perkin-Elmer Model 240 Elemental Analyzer. F & M Model 185 CHN Analyzer. Technicon CHN-Analyzer. Aminco C and H Analyzer. Imperial College South Kensington London S.W.7; 10 a.m. to 5 p.m. Friday 1st LONDON on “C H and N Analyzers.” PRINTED BY W. HEFFER h SONS LTD.. CAMBRIDGE. ENGLAND.

ISSN:0037-9697    

DOI:10.1039/SA966030104b

出版商:RSC    

年代:1966

数据来源: RSC