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V O L U M E 26, NO. 7, J U L Y 1 9 5 4 sugar fraction has revealed the presence of radioactive mannose, fructose, glucose, and an unknown polyhydroxy compound. This led the authors to believe that the transformation of glucose to other monosaccharides in this case is probably following a typical epimerization mechanism. Lactic acid has been identified as the major constituent in the acid fraction and was isolated by means of silica-gel column chromatography. The specific activity of the latter was found to be one half as much as that of glucose, which indicates that a Ca-Cs split is involved in the lactic acid formation. The presence of a small amount of radioactive glycolic acid as well as three other unknown radioactive acids wah nlso demonstrated by radioautography. A Paper Chromatographic Method of Analysis for Acetovanillone in Oxidized Alkaline Cleaved Waste Sulfite Liquor. E. T . KEIYILLE AND G. W.SHREVE.
A method of analysis for acetovanillone in oxidized alkaline cleaved waste sulfite liquor which can be completed in about 5 hours has been developed. An accuracy within *5% is indicated. Investigation of Chemical Species in Highly Radioactive Solutions by Means of Chromatographic Techniques. A. S.WXI.SON. The nature of chemical species in highly radioactive solutions is in general difficult to determine because of the hazardous nature of the solutionh. Chromatography, however, is a convenient tool because a small quantity of the solution to be investigated can be used. Experiment9 using both electrochromatography and paper chromatography were presented to illustrate the utility of the tool. Where possible. conclufiionswere drawn relative to the nature of the chemical species present in these solutions.
Society for Analytical Chemistry T vEETINC;S
of t h e North of England Section (Kovember 28)
A and t h e Scottish Section (December 16) of t h e Society for
Analytical Chemistry R. L. M. Synge, Rowett Research Institute, Bucksburn, Aberdeen, spoke on “Principles of Chromatography.”
Chromatography was defined as a method for separating substances by percolation of fluids through porous and powdered media, and the countercurrent nature of the chromatographic process was explained. Three types of chromatographic operating procedures were described -elution development, frontal analysis, and displacement development-and gas-liquid, gas-solid, liquid-liquid, and liquid-solid equilibria were discussed. The use of proper detection methods in application of ion exchange resins was emphasized, and diiliculties with molecules of molecular weight greater than 500 was described. The speaker’s latest work was done on the separation of large molecules on collodion membranes. T h e council of t h e society has approved t h e formation of a Western Section, t h e inaugural meeting of which was held M a y 8 a t Newport. T h e 44th meeting of t h e Physical Methods Group was held March 9 in London. Differential Refractometers, Theory and Construction. G. H. E’. SEIFLOW, Research Department, I.C.I., General Chemicals, Widnes, Lancs. The theory of the operation of differential refractometers was outlined. The general construction of both visual and photoelectric refractometers was described and a more detailed description of a recording refractometer designed by the author was given. Application of Differential Refractometry. R. HILL, Research Department, I.C.I., General Chemicals, Widnes, Lancs. Differential refractometry has been applied to the determination of the purity of organic compounds with particular reference to gamma-benzene hexachloride (lindane). The method involves comparison of the refractive index of a saturated solution of pure standard with that of a solution made from the sample in such a way that all the components are dissolved except a small amount of the major
component. The difference in refractive index between the two solutions can be a n accurate measure of the impurity content of the sample. The technique is based on the one outlined by Hughes and Young (Nature, 1949) but uses refractive index in place of vapor pressure as the measured physical property. Interferometric Refractometry. A Survey of Methods. H. G. KUHN,Balliol College, Oxford. Two types of instruments are used for the measurement of refractive indices by interference. The Jamin refractometer is based on interference alone and uses an extended oource, while the Rayleigh refractometer is essentially a diffraction grating using a slit source. The latter type of instrument suffers from an extreme smallness of the fringe spacing; this makes the use of a fiduciary fringe system necessary, instead of a cross-wire, which complicates the design. The thick, accurately worked glass plates of the conventional Jamin refractometer give rise to difficulties which can easily be avoided if pairs of thin plates, with spacers, are used instead. Limitations of interferometric methods employing compensators and white light fringes were discussed. The wide range of applications of interferometric refraetornetry t o problems of chemical analysis of gases and liquids was stressed. I t appears that the method is strangely neglected in England: this may be due to the lack of sufficiently simple and robust instrument in the home market.
Use of a Rayleigh Interferometer for Estimating Trichloroethylene. R. E. JAHN, Research & Development Department, British Oxygen Co., Morden, London S.W.19.
A Rayleigh-type gas interferometer was used to analyze mixtures of 0 t o 3% trichloroethylene vapor in air by volume. It enabled continuous analyses of the trichloroethylene-air mixtures to be made with about 1-minute intervals between readings. Four methods of calibration were used. The first utilized existing experimental data on the refractive index of trichloroethyleneair mixtures in conjunction with a n experimentally found optical constant of the interferometer. The second consisted of a direct calibration against chemical analyses. The third involved experimental calibration against gas mixtures prepared in a 6-liter vessel. The fourth was similar to the third method, except that the gas mixtures were produced by injecting liquid trichloroethylene a t a known rate into an air stream of measured flow rate. Corrections were made, where necessary, for atmospheric pressure and temperature changes, nonlinearity of the relation between scale readings, and change of refractivity and dispersion effects. For trichloroethylene-air mixtures containing about 0.5% of trichloroethylene by volume, the accuracy of analysis using the interferometer was within f 2 % so that a change in concentration of 100 p.p.m. could be measured. The limit of accuracy was dependent on the calibration, as the instrument could always be adjusted more accurately. T h e 45th meeting of the Physical Methods Group was held April 6 in London. The subject of the meeting was mass spectrometry. Mass Spectrometer as an Analytical Tool. G. P. BARNARD, Physics Division, National Physical Laboratory, Teddington, Middlesex. A brief description of some modern instruments, techniques in operation, and analytical procedures was given. Some examples of quantitative organic and inorganic analysis were considered. I n respect of accuracy and speed in these analytical applications, mass spectrometry is shown to compare favorably with other physical methods of analysis. The use of the isotope dilution method for trace element determinations in solids was described. The paper concluded with some comment on other uses of the mass spectrometer for impurity determinations. Some Applications of the Mass Spectrometer to Studies of Chemical Reaction. R. I. REED,29 Havelock St., Glasgow W.l. The mass spectrometer has many applications to chemical problems, and without its use much information would be unobtainable, or a t best deduced by inference by other means. Three such uses of mass spectrography, in studies of chemical reactions, were described. The identification and estimation of small quantities of material, although limited to compounds of a suitable volatility, are of considerable assistance in the examination of by-products from chemical reactions. The recognition of these might otherwise require the use
1250 of large scale experiments, which is not always desirable, nor in the case of isotopic tracer experiments practicable. The abundance of stable tracer elements in reaction systems may be determined where the use of stable isotopes is convenient (carbon131, or essential, as with nitrogen, which is used in studies of metabolic processes as well as investigations into reaction mechanisms. Mass spectrometry may also be used as a substitute for alternative methods of isotopic analysis where, while not so convenient as the customary methods, its application becomes essential by reason of the small quantities available for examination. I n particular, such studies include the determination of the deuterium content of a limited class of aromatic organic acids by assay of not. more than 2-mg. samples. Attempts t o minimize some of the difficulties inherent in this method were described. A joint meeting of t h e Scottish Section of the Society for Analytical Chemistry with the Aberdeen and District Sections of t h e Chemical Society, t h e Royal Institute of Chemistry, and t h e Society of Chemical Industry was held April 1 in Robert Gordon’s Technical College, .4berdeen. Some Applications of the Newer Techniques i n Analytical Chemistry. J. R. NICHOLLS,The Government Laboratory, Clement’s I n n Passage, Strand, London W.C.2.
ANALYTICAL CHEMISTRY fects of variations in experimental conditions were described. The application o f the method t o the analysis of oral tablets of penicillin was described in detail with many examples. A comparison was made of the results by the method described with those found by biological assay. Micromethod for Determination of Bromide in Presence of ChloElectromedical Research ride. G . HUNTER. ~ N DA. A. GCJLDSPIXK, Unit, Medical Research Council, Stoke Mandeville Hospital, ..iylesbury, Bucks. Conditions have been found for quantitative conversion of micro amounts of bromide to bromate by hypochlorite and for the quantitative formation of tetrabromorosaniline, as a basis for colorimetry, from bromine so formed with excess of added bromide. The colorimetric procedure is applicable in the range 0 to 5 y of bromide in 5 ml. of solution. I n the same volume accurate measurements can be made of 0.1 y of bromide, and of even smaller quantities by reducing the volume. The method is independent of the presence of chloride. although chloride has some effect on potential interference by chlorate and iodate. With a gross excess of chloride, about 200 equivalents of iodate or 6000 to 8000 equivalents of chlorate are necessary to cause appreciable interference with 1 equivalent of bromide. The production of chlorate in relatively large amounts is an integral part of the method, but experimental conditions are such as to avoid interference from it. The method is simple and readily adaptable t o multiple microdeterminations of bromide.
The classical techniques of analytical chemistry are primarily designed for the separation of the material to be determined in a form capable of measurement either gravimetrically or volumetrically. This involves the application of chemical principles t o remove interfering substances and to separate the material in a physical state such that a desired measurement of weight or volume can be made. The newer techniques are concerned with separations effected by the application of recently developed chemical principles or by t h e employment of physical processes, and the final determination may involve the measurement of any physical property. There are few new chemical principles which have been applied in wch a way as t o warrant description as new techniques: but physical operations have been so widely developed of recent years t h a t there is danger of their being regarded as tools of the skilled technician rather than part of the equipment of an analyst. The modern analytical chemist finds it essential to be familiar with a t least some of them, as by their means he is able t o acquire information unobtainable by classical methods. Such techniques are not in place of, but complementary and supplementary to, classical ones. They are all .pecialized toolsand assuch have theirlimitations; but the fully qualified craftsman must have them in his tool chest, so t h a t they can be used either singly or in combination to obtain the maximum information and the best results. Examples were given of some of the newer techniques, and reference was made to the use of statistics and to the employment of approximate and simplified methods. Some applications of several of these techniques in medical chemistry, clinical analysis, plastics analysis, and forensic work were described.
The manometric and colorimetric techniques for the determination of esterases were described. The assumption that any ester would be hydrolyzed by the esterase had been shown t o be untrue. Experiments with organophosphorus compounds had shown t h a t rabbit serum contained two types of esterase hydrolyzing p-nitrophenyl and phenyl esters, and t h a t r a t intestinal mucosa contained two esterases that hydrolyzed tributyrin, one of these being lipase. The use of organophosphorus compounds would undoubtedly increase the knowledge of these enzymes: the lack of knowledge is probably due t o t h e fact t h a t the activities of t h e different esterases have not yet been separated and their properties examined.
At a meeting held in London, M a y 5 , three papers were presented.
Determination of Sugars. G . HARRIS, Brewing Industry Research Foundation, Nutfield, Redhill, Surrey.
Determination of Phosphate in the Presence of Soluble Silicates. Application to Basic Slag. H. N. WILSON,Research Department, I.C.I., Ltd., Billingham, Yorks. I t was shown t h a t soluble silicic acid, even after prolonged boiling t o polymeriee it, is readily converted t o silicomolybdic acid by sodium molybdate in hot acid solution, and is precipitated as quinolinium silicomolybdate under the same conditions as is the phosphomolybdate, which seriously interferes with the determination of phosphate. This interference is overcome by the addition of citric acid, which forms a complex with molybdic acid of such stability t h a t its reaction with silicic acid is prevented, whereas the reaction with phosphoric acid proceeds normally. Experimental results were quoted, and details were given for the analysis of basic slag, for which material the new method is superior to the statutory method. The use of a citricmolybdic acid reagent also simplifies the accurate determination of phosphate in fertilizers. Spectrophotometric Estimation of Total Penicillins by Conversion to Penicillenic Acid and the Importance of Copper in Controlling the Reaction. F. G . STOCK,City Analyst’s Laboratory, 152 Great Charles S t . , Birmingham 3. A method for the estimation of total penicillins was proposed: it is a modification of that described by Herriott. The importance of the presence and concentration of copper was demonstrated and the ef-
A joint meeting of the Microchemistry Group of the Society for Analytical Chemistry and the London Section of the Royal Institute of Chemistry was held May 7 a t the University, Reading. Demonstrations were given in the Agricultural Chemistry Research Laboratory by I. Smith and J. B. Jepson on “New Methods in Paper Chromatography” and by J. Tinsley on “Shandon Continuous Paper-Electrophoresis rlpparatus.” Three papers were presented. Determination of Esterases. W. N. ALDRIDGE,Toxicology Research Unit, Serum Research Institute, Woodmansterne Rd., Carshalton, Surrey.
Paper chromatographic procedures for the analyses of raw materials for brewing were described and illustrated by the results of analyses of brewer’s wort, barley extracts, and beers for their constituent sugars. The standard errors of the determinations of individual sugars were discussed: these were not greater than 1 3 % for sugars present in amounts of 100 to 300 y on the chromatogram, but rose t o f10% f o r those present in amounts of 10 t o 30 y . The defects in t h e method were discussed, and some suggestions were made for overcoming them. Some possible future trends in the development of carbohydrate analysis were discussed. Measurement of Isotopes of Carbon and Hydrogen. R. F. GLASCOCK, National Institute for Research in Dairying, Shinfield, Nr. Reading, Berks. Methods available for counting the radioactive isotopes carbon-14 and tritium in solid compounds were briefly surveyed, and the more efficient gas-counting methods in current use were described. An apparatus and method for determining carbon-13, carbon-14, and tritium present together in a single organic sample were described. Some difficulties involved in proportional counting techniques were described, such as the “memory effect” due t o the contamination of counters by exchange with tritium, which makes hydrogen a n unsuitable form for counting. Tritiomethane is difficult to handle, but butane is a good counting gas in the Geiger region. I n the apparatus descrihed, this gas was produced by the reaction of tritium with dry n-butyl magnesium bromide.
