iv SUMMARIES OF PAPERS IN THIS ISSUE [July, 1966Summaries of Papers in this IssueSeparation and Determination of Small Amounts of TinA REPORT OF WORK UNDERTAKEN ON BEHALF OF THE METALLIC IMPURITIES I N ORGANIC MATTERSUB-COMMITTEE OF THE ANALYTICAL METHODS COMMITTEE.A method is presented for the selective extraction of tin(1V) iodide fromsulphuric acid solution into toluene. Tin(1V) is then returned to aqueoussolution by shaking the toluene extract with dilute sodium hydroxide solution.The metal is finally determined by spectrophotometric measurement of thecolour of the complex formed between tin(1V) and catechol violet.method is quick, simple, sensitive and highly selective.E. J. NEWMAN and P. D. JONESAnalytical Laboratories, Hopkin and Williams, Ltd., Freshwater Road, ChadwellHeath, Essex.TheAnalyst, 1966, 91, 406-410.Determination of Trace Amounts of Copper in Niobium andTantalum by Atomic-absorption SpectroscopyCopper may be determined in niobium and tantalum a t the 1 to 10 p.p.m.level by extraction of copper 8-hydroxyquinolinate from a fluoride mediuminto ethyl acetate a t pH 4.5, and by direct atomic-absorption spectroscopy ofthe extract in an air - propane or air - acetylene flame at 3247 A.Optimumconditions of pH, reagent concentration and solvent composition have beenestablished, and a study of the effect of other cations and anions is presented.Only titanium(1V) and molybdenum (VI) cause interference when present in100-fold excesses, but even these may be masked by the addition of hydrogenperoxide.G.F. KIRKBRIGHT, M. K. PETERS and T. S. WESTChemistry Department, Imperial College, London, S.W.7.Analyst, 1966, 91, 411-417.The Analysis of Titanium Dioxide Pigments by Spark- sourceMass SpectrographyGraphite, silver and gold powders have been investigated as conductingmedia in the analysis of titanium dioxide pigments for trace elements by solid-source mass spectrography. It is concluded that graphite and silver a.resatisfactory, and that by using both these electrode systems the only elementsthat cannot be determined are sodium and copper.It has been shown that by using niobium in low concentration as aninternal standard, quantitative analysis is possible ; the coefficient of vari-ation of the results being approximately 15 per cent.Sensitivity factors for44 elements relative to niobium in a graphite matrix, and 3 elements relativeto niobium in a silver matrix, have been determined. The results of thedetermination of 27 elements commonly present in titanium dioxide pigmentsare given. The total time for a quantitative analysis is approximately 3hours, and it is possible to analyse up to 8 samples in a working day of 8 hours.P. F. S. JACKSON and J. WHITEHEADBritish Titan Products Company Ltd., Billingham, Co. Durham.Analyst, 1966, 91, 418-427Vi SUMMARIES OF PAPERS IN T H I S ISSUEDetermination of Tetra-alkyl Lead Vapour and Inorganic LeadDust in AirMethods are described for the determination of particulate lead and oftetra-alkyl lead vapour in air, by passing the atmosphere under test through aglass-fibre filter and then through a hydrochloric acid solution of iodine mono-chloride.Tetraethyl lead and tetramethyl lead are collected in this solutionby means of their reaction with iodine monochloride to give the correspondingdialkyl lead ions. The lead collected on the filter is extracted with a nitricacid - hydrogen peroxide reagent, and the amount present is determinedcolorimetrically as lead dithizonate. This may be done automatically withthe Technicon Auto-Analyzer, or manually with a comparator and a standarddisc.Manual and automatic procedures are also given for the determination ofthe amount of tetra-alkyl lead collected. The manual method involvesreaction of the dialkyl lead ions with dithizone a t high pH and matching thecolour of the dialkyl lead dithizonate with a standard disc.In the automaticprocedure, the dialkyl lead is converted to the inorganic state before reactionwith dithizone and colorimetric measurement as lead dithizonate.The methods are designed for the measurement of lead-in-air concentra-tions down to 0.1 mg of lead per 10 cubic metres of air, with sampling periodsof a t least 8 hours. A modified method based on a sampling period of halfan hour, and having a sensitivity of 0.3 mg of lead per 10 cubic metres, isalso described.R. MOSS and (the late) E. V. BROWETTThe Associated Octel Co. Ltd., Ellesmere Port, Chcshire.[July, 1966Analyst, 1966, 91, 428-438.An Examination of Some of the Factors Affecting the Determinationof Carbon Dioxide by Non-aqueous TitrimetrySome of the factors, including choice of absorbent, indicator and titrant,that affect the determination of carbon dioxide by non-aqueous titrimetryare examined experimentally.The results of this examination are used togive a procedure that is recommended for the determination of milligramamounts of carbon dioxide.The method involves absorption of the carbon dioxide in a 5 per cent. v/vsolution of ethanolamine in formdimethylamide, followed by titration withstandard tetrabutyl ammonium hydroxide in benzene - methanol solutionto a visual end-point with thymolphthalein indicator.P. BRAID, J. A. HUNTER, W. H. S. MASSIE, J. D. NICHOLSON andB. E. PEARCEHeriot-Watt University, Chambers Street, Edinburgh 1.Analyst, 1966, 91, 439-444.Thin-layer Chromatography of Epoxide ResinsA simple thin-layer chromatographic technique is described for separatingcommercial epoxide resins into their various components.A method isclcscribed for the quantitative determination of the monomer content ofbisphenol A - epichlorohydrin resins. The various components present inepoxide resins are separated on glass plates coated with silica gel G withchloroform as developing solvent. Optimum separation is achieved by givingtwo developments in chloroform. Details are given of a method for detectinghydrolysable chlorine containing components present in the resin. By themethod described it is possible to distinguish between similar resins fromdifferent manufacturers.R.G. WEATHERHEADYarsley Research Laboratories, Chessington, Surrcy.Analyst, 1966, 91, 445-448viii SUMMARIES OF PAPERS I N THIS ISSUEThe Determination of Diethyl Phthalate in Cosmetic PreparationsAs alternatives to simple hydrolysis and titration, three methods forthe determination of diethyl phthalate in ethanolic preparations such asperfumes, lacquers, deodorants, varnishes and paints are described. A methodsuitable as a screening test for large numbers of samples involves the use ofdirect gas chromatography. Another method involves a simple clean-up ofthe sample followed by column chromatography and determination of theester by its absorption in the ultraviolet. A further and more accurate methodis based on hydrolysis of the ester and gravinietric determination of thephthalic acid after conversion to phthalanil.W.HANCOCK, B. A. ROSE and D. D. SINGERMinistry of Technology, Laboratory of the Government Chemist, Cornwall House,Stamford Street, London, S.E. 1.Analyst, 1966, 91, 449-454.[July, 1966The Analysis of Fats Containing Cyclopropenoid Fatty AcidsCyclopropenoid compounds are labile in the presence of acidic reagents,silver nitrate and mercuric acetate; they are partially destroyed in the courseof gas - liquid chromatographic analysis; and they give a mixture of straightand branched-chain acids on hydrogenation.The difficulties associated with the isolation of methyl sterculate andof the analysis of fats for sterculic and malvalic acids are discussed.T.W. HAMMONDSTropical Products Institute, Gray’s Inn Road, London, W.C. 1.and G. G. SHONENorth Staffordshire College of Technology, Stoke-on-Trent, StaffordshireAnalyst, 1966, 91, 455-458.The Determination of Vitamin D in the Presence of Vitamin AA method has been developed for eliminating vitamin A interference inthe determination of vitamin D. The procedure depends upon the oxidationof vitamin A alcohol by means of manganese dioxide to vitamin A aldehyde,which reacts with p-aminobenzoic acid to form a derivative that is readilyextracted from organic solvents with aqueous sodium hydroxide solution.Vitamin D remains in the organic solvent. Final traces of impurities thatinterfere in the vitamin D determination are removed by chromatography onfloridin earth and on alumina. Vitamin D is determined by the antimonytrichloride colour reaction.F.SAID. M. K. SALAH and P. GIRGISAnalytical Chemistry Department, Faculty of Pharmacy, Cairo University, Egypt,U.A.R.Analyst, 1966, 91, 459-463.Primary Analytical Standards for Plutonium: Quantitative Separationof Plutonium from Dicaesium Plutonium HexachlorideShort PaperF. J. MINERThe Dow Chemical Co., Rocky Flats Division, P.O. Box 888, Golden, Colorado 80401.Analyst, 1966, 91, 464-465.The Micro Determination of Isoniazid by N-BromosuccinimideShort PaperM. 2. BARAKAT and MONIER SHAKERBiochemistry Department, Faculty of Veterinary Medicine, Cairo University, Giza,Cairo, Egypt.Analyst, 1966, 91, 466-467.An Ultraviolet Spectrophotometric Method for Determining3-Amino- 1H- 1,2,4-triazoleShort PaperB.D. 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