iV THE ANALYST [September, 1974THE ANALYSTEDITORIAL ADVISORY BOARDChairman: H. J. Cluley (Wembley)*L. S. Bark (Solford)R. Belcher (Birmingham)1. J. Bellamy, C.B.E. (Waltham Abbey)L. S. Birks (U.S.A.)E. Bishop (Exeter)OR. M. Dagnall (Hunfingdon)E. A. M. F. Dahmen (The Netherlands)*J. B. Dawson (Leeds)A. C. Docherty (Billingham)D. Dyrssen (Sweden)*W. T. Elwell (Birmingham)*D. C. Garratt (London)1. Hoste (Belgium)D. N. Hume (U.S.A.)H. M. N. H. Irving (Leeds)M. T. Kelley (U.S.A.)*J. A. Hunter (Edinburgh)W. Kemula (Poland)*G. F. Kirkbright (London)G. W. C. Milner (Harwell)G. H. Morrison (U.S.A.)*J. M. Ottaway (Glasgow)*G. E. Penketh (Billingham)S. A. Price (Tadworth)D. 1. Rees (London)E. B. Sandell (U.S.A.)*R. Sawyer (London)A.A. Smiles, O.B.E. (Harwell)H. E. Stagg (Manchester)E. Stahl (Germany)A. Walsh (Australia)T. S. West (London)P. Zuman (U.S.A.)*A. Townshend (Birmingham)* Members of the Board serving on the Executive Committee.NOTICE TO SUBSCRIBERSSubscriptions for The Analyst, Anolytlcal Abstracts and Proceedings should beThe Chemical Society, Publications Sales OiVce,Blackhorse Road, Letchworth, Herts.Rates for 1974(other than Mambara of the Society)sent to:(a) The Analyst, Analytical Abstracts, and Proceedings, with indexes . . . . f37.00(b) The Analyst, Analytical Abstracts printed on one side of the paper (withoutindex), and Proceedings . . . . . . . . . . . . . . f38.00(c) The Analyst, Analytical Abstracts printed on one side of the paper (withindex), and Proceedings .. . . . . . . . . . . . . f45.00The Analyst and Analytical Abstracts without Proceedings-(e) The Analyst, and Analytical Abstractt printed on one side of the paper (without(d) The Analyst and Analytical Abstracrs, with indexes . . . . . . . . f34.00index) . . . . . . . . . . . . . . . . . . f35.00( f ) The Analyst, and Analytical Abstracts printed on one side of the paper (withindex) . . . . . . . . . . . . . . . . . . f 42.00(Subscriptions are NOT accepted for The Analyst and/or for Proceedings alonevi SUMMARIES OF PAPERS I N THIS ISSUE [September, 1974Summaries of Papers in this IssueThe Rapid Determination of the Total Dry Extract of WinesA method is described whereby the total dry extract of wines, includingsweetened and fortified wines, can be determined from knowledge of theirrelative densities and alcoholic strengths.The method is designed to be used inconjunction with the rapid refractometric method used in this laboratory forthe determination of the alcoholic strength of wine and requires no furthermeasurements, other than that of temperature, to be made.P. J. WAGSTAFFEDepartment of Trade and Industry, Laboratory of the Government Chemist, Corn-wall House, Stamford Street, London, SE1 9NQ.Analyst, 1974, 99, 537-543.Determination of Cyanide Ion in Cyano-complexesA method is described for the determination of the CN- ion in a variety ofcyano-complexes. The method is based upon mixing and grinding the samplewith flowers of sulphur and potassium chloride in the ratio of 1 : 2 : 2; theaddition of potassium carbonate is also essential with cyano-acid complexes.After mixing, a micro-amount is fused in a test-tube a t about 300 "C for2 minutes and the tube is then broken in a few millilitres of water.In thisway the CN- ion is converted quantitatively into CNS-, which is determinedcolorimetrically. The average recovery is 98.54 per cent.S. K. TOBIA, Y. A. GAWARGIOUS and M. F. EL-SHAHATChemistry Department, Ain Shams University, and Micro-analytical ChemistryLaboratory, National Research Centre, Dokki, Cairo, Egypt.Analyst, 1974, 99, 544-546.The Determination of Small Amounts of Water inGases Using Karl Fischer ReagentTwo methods are described for the determination of water in gases.In the first method, the gas being examined is led into a Karl Fischertitration cell, and water is titrated directly.In the second method, waterfrom a gas stream is absorbed on a short column of a gas-chromatographicstationary phase. On heating the column, water is liberated and is carriedover to the Karl Fischer cell in a stream of dry nitrogen and then titrated.The validity of the direct titration method has been checked by examininggas streams that had been passed over ice a t various temperatures.E. E. ARCHERBritish Petroleum Limited, Group Research and Development Department,Epsom Division, Epsom, Surrey.and J. HILTONBP Chemicals International Limited, Grangemouth, Stirlingshire, Scotland.Analyst, 1974, 99, 547-550September, 19741 SUMMARIES OF PAPERS I N THIS ISSUEThe Use of Tiron in the Microchemical Analysisof MineralsThe complexes formed by tiron with aluminium, iron and titanium canbe used to determine these elements colorimetrically on a single aliquot ofthe solution of a mineral.The tiron also renders these solutions verysuitable for analysis in a flame, the sodium from the tiron acting as a flamebuffer and the complexing properties inhibiting chemical interferences. Asingle aliquot of solution can therefore be used to determine several elementsand the procedure can form the basis df a scheme for the microchemicalanalysis of minerals. Little is known of the use of tiron for the deter-mination of aluminium and this paper describes tests made on the usefulnessof this method.W. J.FRENCH and S. J. ADAMSGeology Department, Queen Mary College, University of London, Mile End Road,London, E.l.Analyst, 1974, 99, 551-554.Oxidation Procedures in the Assay of Some Drugs Containing aDiphenylmethylene Ether or Diphenylmethyleneamino GroupMethods for the oxidation of diphenylmethylene ethers and diphenyl-methyleneamines have been compared ; oxidation with aqueous acidic di-chromate is advocated for the former and with alkaline permanganate forthe latter in the assay of drugs containing these groups. The possible mech-anisms involved are proposed.B. CADDY, F. FISH and J. TRANTERDivision of Pharmacognosy and Forensic Science, School of Pharmaceutical Sciences,University of Strathclyde, Glasgow, G1 1XW.Analyst, 1974, 99, 555-564.Determination of the Tyramine Content of South African Cheesesby Gas - Liquid ChromatographyThe tyramine content of foodstuffs and beverages is of pharmacologicaland therapeutic importance.A simplified method for its extraction fromvarious cheeses and the application of gas-chromatographic analysis arepresented.E. R. KAPLAN, N. SAPEIKADepartment of Pharmacology, Medical School, Observatory, Cape Province,South Africa.and I. M. MOODIEFishing Industry Research Institute, University of Cape Town, Rondebosch, CapeProvince, South Africa.Analyst, 1974, 99, 565-569.The Determination of Residues of Volatile Fumigants in GrainReport by the Panel on Fumigant Residues in Grain.COMMITTEE FOR ANALYTICAL METHODS FOR RESIDUES OFPESTICIDES AND VETERINARY PRODUCTS IN FOODSTUFFS (DR.N.A. SMART, SECRETARY)Ministry of Agriculture, Fisheries and Food, Plant Pathology Laboratory, HatchingGreen, Harpenden, Hertfordshire.Analyst, 1974, 99, 570-576.Vixii SUMMARIES OF PAPERS I N THIS ISSUEModified Methylene Blue Method for the Micro - determinationof Hydrogen Sulphide[September, 1974A method is described whereby hydrogen sulphide can be determinedsimply and rapidly in the 0.04 to 0.4 pmol range.N. A. MATHESONRowett Research Institute, Bucksburn, Aberdeen, AB2 9SB.Analyst, 1974, 99, 577-579.The Determination of Nitrogen- 15 in Plant Material With anEmission SpectrometerInstrumental and procedural modifications for the use of the Statron,Model NOI-5, emission spectrometer in the determination of nitrogen- 15 arereported.An interpolative method is recommended for estimating thebackground of the nitrogen-14 - nitrogen-15 peak. This method gives alinear relationship between apparent percentage of nitrogen- 15 and the actualpercentage of nitrogen-15 over the lower, most commonly used range. Assaysrepeated at intervals over 2 months had standard errors of 0-75 per cent.The preparation of nitrogen gas samples for the emission spectrometerhas been treated as a separate operation from the determination of total plantnitrogen. After a standard Kjeldahl digestion of the plant material, theammonium ion is precipitated with a Nessler reagent. The supernatant isrejected and the precipitate treated with dilute hydrochloric acid to give anammonium chloride solution, from which an aliquot is taken for a Dumascombustion in a discharge tube.Two operators can prepare and measure upto fifty samples per day. The method has been used to analyse a range of planttissues from an apple nutrition experiment, during which replicate digestionsand analyses gave values for nitrogen- 15 enrichment that differed by anaverage of only 2.5 per cent.C. P. LLOYD-JONES, G. A. HUDD and D. G. HILL-COTTINGHAMUniversity of Bristol, Department of Agriculture and Horticulture, Research Station,Long Ashton, Bristol, BS18 9AF.Analyst, 1974, 99, 580-587.Atomic-absorption Determination of Some Common Trace Elementsin Aluminium Oxide and Other Aluminium Compounds Using aCo-precipitation Separation TechniqueAtomic-absorption spectroscopy has been used to determine micro-gram amounts of calcium, iron, manganese, silicon, titanium, vanadiumand zinc in aluminium oxide and other aluminium-rich materials after co-precipitation of these elements on zirconium hydroxide from an alkaline solu-tion of the sample.The proposed method serves both to separate the trace elements fromaluminium and also to concentrate the elements, thus improving bothaccuracy and sensitivity. The method is shown to be as accurate andprecise as colorimetric procedures, very much quicker and less tedious.The trace constituents are determined in the range 5 to 400 pg in thefinal 25 ml of sample solution on a 2-g sample of aluminium oxide, and in therange 10 to 2000 pg on a 0.5-g sample of other materials (25-ml final volume).Interference effects are reduced to a minimum by separation of theelements from aluminium and the provision of closely matched standardsolutions.P.N. W. YOUNGNew Zealand Aluminium Smelters Limited, Invercargill, New Zealand.Analyst, 1974, 99, 588-594September, 19741 SUMMARIES OF PAPERS I N THIS ISSUEAtomic-absorption Studies on the Determination of Antimony,Arsenic, Bismuth, Germanium, Lead, Selenium, Tellurium and Tinby Utilising the Generation of Covalent HydridesA method for the determination of arsenic, bismuth, germanium, lead,antimony, selenium, tin and tellurium by means of hydride generation isdescribed. The hydrides are generated by adding the acidified sample todilute (1 percent.m/V) sodium borohydride solution. The liberated hydridesare passed directly into a 17 cm long silica tube mounted in an air - acetyleneflame. The advantages of the proposed system are its simplicity, highsensitivity, high speed of analysis and the fact that background correctionfacilities are not required.The generation of plumbane for analytical purposes does not appearto have been reported previously.K. C. THOMPSON and D. R. THOMERSONShandon Southern Instruments Ltd., Frimley Road, Camberley, Surrey, GU16 5ET.Analyst, 1974, 99, 595-601.Electrolytic Extraction Combined With Flame Atomic Absorptionfor the Determination of Metal Ions in Aqueous SolutionMetals were deposited from aqueous solutions onto an iridium wire eitherby electrolysis at pH 2 or by auto-deposition at pH 9.The amount depositedwas determined by atomisation with an air - hydrogen flame into a long-tube(10 cm) atomic-absorption spectrophotometer. The sensitivities obtained byelectrolysis were comparable with those obtained by conventional sampleaspiration for magnesium, lead and zinc and an order of magnitude greater forcadmium, copper and mercury. The presence of other ions in the samplesolution generally reduced the sensitivity of the method.J. B. DAWSON, D. J. ELLIS and T. F. HARTLEYDepartment of Medical Physics, General Infirmary, Leeds, LS 1 3EX.Mrs. M. E. A. EVANS and K. W. METCALFJohnson Matthey & Co. Ltd., Group Research Laboratory, Wembley, Middlesex.Analyst, 1974, 99, 602-607.A Potentiometric Titration Method for the Rapid Determinationof Salt in Meat ProductsA method is described for the rapid determination of salt in meat pro-ducts by titration of the macerated sample with silver nitrate. The acidicand oxidising conditions specified permit the use of an ion-selectiveelectrode with a silver sulphide membrane in the potentiometric detectionof the end-point. The method is slightly more precise and very much morerapid than existing routine and reference methods.M. KAPEL and J., C. FRYProcter Department of Food and Leather Science, Leeds University, Leeds, LS2 9 JT.An~lyst, 1974, 99, 608-611.The Use of Filter-papers in the Determination of Nitrogen in FoodsD. PEARSONNational College of Food Technology, University of Reading, St. George’s Avenue,Weybridge, Surrey.Analyst, 1974, 99, 612.xii