iv SUMMARIES OF PAPERS I N THIS ISSUE [February, 1966Summaries of Papers in this IssueSome Sensitive and Selective Reactions in InorganicSpectroscopic AnalysisA Special LectureT. S. WESTChemistry Department, Imperial College, London, S. W. 7.Analyst, 1966, 91, 69-77.Recent Developments in the Measurement of Nucleic Acidsin Biological MaterialsA Supplementary ReviewSUMMARY OF CONTENTSIntroductionPreparation of tissue samples for nucleic acid determinationsPrecautions during removal of tissuesExtraction of acid-soluble compoundsExtraction of lipidsMethods of determining nucleic acids in the tissue residue1. The procedure of Schmidt and ThannhauserThe use of alkaline hydrolysis to separate RNA from DNAThe RNA fraction of the alkaline digestThe DNA fraction of the alkaline digestRecommendations for the use of the Schmidt - Thannhausermethod2.The Schneider procedure3.4. Other proceduresThe procedure of Ogur and RosenGeneral recommendations for nucleic acid determinationH. N. MUNRO and A. FLECKDepartment of Biochemistry, The University of Glasgow.Analyst, 1966, 91, 78-88.REPRINTS of this Review paper will soon be available from the Secretary,The Society for Analytical Chemistry, 14 Belgrave Square, London, S.W. 1,a t 5s. per copy, post free.A remittance for the correct amount, made out t o The Society for-4nalytical Chemistry, MUST accompany every order; these reprints are notavailable through Trade Agents.A Sensitive and Selective Spectrophotometric Procedurefor the Determination of PhosphorusPhosphorus as phosphate is determined by an amplification procedurein which the heteropoly acid H,PO,(MOO,)~, is formed and extracted awayfrom excess of molybdate reagent.The 12 molybdate ions associated withthe phosphate are then determined spectrophotometrically a t 710 mp as thegreen molybdenum(v1) complex with 2-amino-4-chlorobenzenethiol in chloro-form. Depending on the procedure used, the effective molar absorptivityfor phosphorus is 96,900 or 359,000. The proposed procedure is thereforemuch more sensitive than previously described methods for phosphorus.Amounts of phosphorus down to 0.2pg (0-008 p.p.m.) may be determined.Large excesses of silicon, germanium, arsenic or antimony do not interfere.A simple masking procedure obviates any interference from up to a 30-foldexcess of tungsten(v1).V. DJURKIN, G.F. KIRKBRIGHT and T. S. WESTChemistry Department, Imperial College, London, S W.7.Analyst, 1966, 91, 89-93February, 19661 THE ANALYST Vprogress in productionBecause BDH is a world supplier its progress in the production of laboratorychemicals reflects the international development of the applications of chemistryand biochemistry in education, research, medicine and industry over the last fiftyyears. It has been remarkable progress, whether considered in relation to methods,equipment or scale of manufacture.Advances in the classical methods have gone hand in hand with the employment ofcompletely new techniques of manufacture and purification ; these, and the cori-tributions of modern chemical engineering, have made it possible for the BDH out-put of reagents to increase by more than a hundred times in the past half-century.This in turn has required equivalent developments in analytical resources, inspec-tion services, distribution facilities and commercial organisation.BDH output in1965 calls for the packaging of several million containers a year of thousands ofwidely diverse and often hazardous chemicals. They reach the laboratories of overa hundred countries in every part of the world.POOLE * LONDON * BRISTOL * LIVERPOOL * MIDDLESBROUGHBOMBAY * TORONTO * JOHANNESBURG * SYDNEY * AUCKLAND LC/ P46SUMMARIES OF PAPERS IN THIS ISSUEThe Determination of Residues of Dimethoate withMulti- band Chromatoplates[February, 1966A method is proposed for the determination of dimethoate residues invegetable material.Tripartite multi-band plates are prepared and used toseparate the dimethoate from co-extracted materials ; spot-area measurementis used to give a quantitative determination of the amount of pestcide.D. C. ABBOTT, MRS. J. A. BUNTING and J. THOMSONMinistry of Technology, Laboratory of the Government Chemist, Cornwall House,Stamford Street, London, S.E.l.Analyst, 1966, 91, 94-97.The Solvent-extraction and Absorptiometric DeterminationIron(I1) and iron(m) can be completely extracted from M sulphuric acidinto a 0.02 M solution of Z-mercaptopyridine- l-oxide and determined absorp-tiometrically at 550 mp.The only significant interference is from copper(I1);the sensitivity of the method is 0.02 p g cm-2.J. A. W. DALZIEL and M. THOMPSONDepartment of Chemistry, Chelsea College of Science and Technology, ManresaRoad, London, S.W.3.Analyst, 1966, 91, 98-101.of Iron with 2-Mercaptopyridine-1 -oxideObservations on the Use of Titan Yellow for the Determinationof Magnesium with Special Reference to Soil ExtractsExamination by paper and thin-layer chromatography of several prepara-tions of titan yellow from different manufacturers has shown them to becomplex mixtures.By using a titan yellow selected chromatographically, it has been possibleto improve the stability and sensitivity of the coloured complex producedwith magnesium. Studies have been made of the effects of alkalis, interferingions and protective colloids, and the use of gelatin with a lithium hydroxide -glycine buffer is proposed for the determination of magnesium in soil extracts.Results have been compared with those obtained by atomic-absorptionspectroscopy and show close correlation.R.J. HALL, G. A. GRAY and L. R. FLY"Ministry of Agriculture, Fisheries and Food, National Agricultural Advisory Service,Kenton Bar, Newcastle upon Tyne.Analyst, 1966, 91, 102-112.An Automatic Method for the Determination of AnionicSurface- active Material in WaterAn automatic version of the methylene-blue procedure for determiningalkylbenzenesulphonates in fresh and saline waters on the AutoAnalyzer isdescribed. Results have been examined statistically and compared with thoseobtained by the manual methylene-blue method.Student's t-test indicatesmore than 90 per cent. probability that the manual and automatic methodswill give the same value. The sampling rate is 14 per hour, and the standard de-viation is 0.04 p.p.m. of Manoxol OT in the range 0 to 4 p.p.m. of Manoxol OT.Whilst chloride, sulphide and sulphate showed no interference when tested,peaty water did interfere with the method. However, the results obtainedshowed a correlation to the colour (in p.p.m. of platinum) of the waterexamined. Emulsification, which causes considerable error in the manualmethod, is completely avoided in the automatic method.A. SODERGRENThe Norwegian Institute for Water Research, Oslo, Norway.Analyst, 1966, 91, 113-118viii SUMMARIES OF PAPERS I N THIS ISSUE [February, 1966Automatic Methods for the Determination of Nitrogen, Phosphorusand Potassium in Plant MaterialMethods are described, for use with the Technicon AutoAnalyzer, thathave been successfully used in the determination of nitrogen, phosphorusand potassium in plant materials. Nitrogen is determined as the indophenol-blue complex on an aliquot of solution after digestion by a micro-Kjeldahltechnique.Alternative methods are suggested for the final determinationof nitrogen dependent on the range of values expected. The “bias” methodis extremely sensitive to small variations in nitrogen levels, and, because ofthis high sensitivity, the recorder signal-to-noise ratio must be high.Methodsare suggested for obtaining a maximum signal-to-noise ratio. Phosphorusand potassium are analysed at the same time on the same sample of ashsolution with a single manifold. Phosphorus is determined colorimetricallyby the yellow phospho-vanadate complex, and potassium by flame photo-metry by using an internal standard of lithium nitrate. Nitrogen deter-minations can be carried out a t a rate of 40 samples per hour, and phosphorusand potassium together a t a rate of 60 samples per hour. The accuracy ofthese determinations is better than those obtained by other recognisedtechniques.J. A. VARLEYChemara Research Station, Seremban, Malaysia.AnaZySt, 1966, 91, 119-126.The Analysis and Composition of Potable Spirits : Determinationof C,, C, and C, Alcohols in Whisky and Brandy byDirect Gas ChromatographyThe determination of the principal C, to C, alcohols in potable spiritsby direct gas chromatography is discussed. Application of this methodto 78 samples of various types of brandy and whisky gives results indicatingthat the total higher alcohol content is not characteristic of the type of spirit,but that the proportions of the alcohols to each other fall into distinct rangestypical of the particular spirituous beverage.D. D. SINGERMinistry of Technology, Laboratory of the Government Chemist, Cornwall House,Stamford Street, London, S.E. 1.Analyst, 1966, 91, 127-134.The Detection of Nanogram Amounts of Fluoride IonShort PaperA. D. WILSON and J. R. COOKEMinistry of Technology, Laboratory of the Government Chemist, Cornwall House,Stamford Street, London, S.E. 1.Analyst, 1966, 91, 135