ANALYTICAL CHEMISTRY1. IntroductionIN many branches of analytical chemistry, apparatus originally designedat great cost for investigating fundamental problems of structure and con-stitution is being applied, sometimes at even greater cost, to more particularuses in qualitative and quantitative analysis. At the same time, to meetthe requirements of various technologies, the scope of analysis is beingwidened to include aspects of structure and of physical form which wereonce the reserve of the physicist.In accepting these changes, the analytical chemist must also accept thathis interpretation of the literature of analysis (which is nowadays to befound under many guises), and of such a reflection of the literature as thisReport, must be made with caution. Some of the methods which seemto provide a universal answer in an analytical field can prove cumbersomewhen applied to the complexities of an actual problem.News of rapidadvance in such methods does not necessarily imply progress towards com-mon adoption; it may only betoken activity in ironing out the snags, dis-covering the limitations, and applying the methods in a succession of differingcontexts. Conversely, little progress in a method may be by no meanssynonymous with obsolescence; it could signify a wide acceptance of estab-lished advantages, perhaps of cheapness and directness-daily there muststill be a great many satisfactory analyses carried out gravimetrically bythose denied the pride of possessing an electrifying instrument.AnalyticulAbstracts for 1961 contains abstracts of over 5000 papers.About aseventh of this number is mentioned in the present Report, and the aimof the Reporters has been to select in such a way as to indicate and illus-trate trends in the various sections. In this they have been helped byAnalytical Abstracts, by Current Chemical Papers, and by such authoritativeand critical reviews as those published from time to time in The Analystand in Analytical Chemistry. They have sought to direct the reader’s atten-tion to such reviews, to papers of fundamental worth, and to new methodsand rea.gents, and then to particular applications which illustrate scope ordevelopment.The topics omitted from last year’s Report,2 vix., instrumental methodsof end-point determination in titrimetry, and electrical methods in general,cover two years’ publications, and are inserted appropriately into theprevious pattern and order. The arrangement of the Report is: (1) Intro-duction.(2) General. (3) Basic Operations and Apparatus. (4) Quali-tative Analysis. (5) Methods of Separation. (6) Gravimetric and Titri-metric Analysis. (7) Instrumental End-point Determinations. (8) Deter-mination of Elements in Organic Compounds. (9) Spectroscopic Analysis.(10) Electrical Methods. (1 1) Thermal Methods.At any rate, there is no lack of progress in analysis as a whole.Analytical Abstracts, the Society for Analytical Chemistry, 1961, 8.a Ann. Reports, 1960, 57, 410398 ANALYTICAL CHEMISTRY2. GeneralIn his retiring address as President of the Society for Analytical Chem-istry, R.C. Chirnside gives a thoughtful appraisal of the processes ofdevelopment of analysis, from simple assessment of the commercial valueof a material or check on its conformity with specification, through its exten-sion with the help of the physicist to properties and quality as well as com-position, to the present diversity of disciplines needed to deal with industrialand academic problems and progress. Without minimising the value ofinformation still provided by classical methods, he develops and discussesa new and much wider concept of analysis. In a study of analytical chem-istry in Great Britain,* Chirnside also considers the place of instrumentaltechniques in modern analysis, and the broad requirements of industrialanalytical organisation and methods of analytical teaching, as well as ofthe individual analyst.H. H. Willard, reviewing sixty years of analyticalchemistry,5 emphasises the great changes in the training for and practice ofanalysis, particularly due to advances in instrumental methods during thelast twenty years.The biennial reviews in Analytical Chemistry are this year 6 concernedwith applications of analysis to air pollution, clinical chemistry, coat-ings, essential oils, fertilisers, food, solid and gaseous fuels, ferrous metal-lurgy, non-ferrous metallurgy, pesticides, petroleum, pharmaceuticals,natural and synthetic rubbers, and water. Witlh a total of nearly 5000references, the reviews are an important collection of information in thesefields.Types of paper and other media available for filtration, paper andcolumn chromatography, electrophoresis, spot reactions, the ring oven andion exchange have been described.' The analytical chemistry of berylliumhas been comprehensively reviewed,8 and a bibliography of references tothe analytical chemistry of thorium has been ~ompiled.~ The BritishStandards Institution has published methods for sampling and analysingtin and tin alloys 10 and copper alloys.ll The performance of cupferronanalogues and derivatives has been critically assessed l2 with the conclusionthat, of the many suggested reagents, only a few are satisfactory althoughsome may repay further investigation.Some modern methods, particularly thin-layer and vapour-phase chroma-tography, have been applied to analysis of petrol, oil, tar, and wax in scien-tific criminology.13 A review has been made of the determination of residual3R.C. Chirnside, Analyst, 1961, 86, 314.R. C. Chirnside, Analyt. Chem., 1961, 33, (12), 25-4.H. H. Willard, Talanta, 1961, 7, 152.Analyt. Chem., 1961, 33, No. 5.A. Griine, Osterr. Chem.-Ztg., 1961, 62, 74.M. R. Verma, Jitendra Rai, and Prabhu Dayal, J . Sci. Ind. Res., India, A , 1961,8L. E. Smythe and R. N. Whittem, Analyst, 1961, 86, 83.loBritish Standards Institution, B.S. 3338: Parts 1, 2, 4-8, 11, 12: 1961.l1 British Standards Institution, B.S. 1748: Parts 1-5: 1961.laA. M. G. Macdonald, Ind. Chemist, 1961, 37, 30.13G. Machata, Arch.Kriminol., 1961, 127, 1.Suppl. to 20 (2) and 20 (3)CARTWRIGHT, WESTWOOD, AND WILSON 399organo-phosphorus insecticides in foodstuffs 1 4 and a method is recommendedfor determining mercury residues in apples and t0mat0es.l~A comprehensive and critical review has been made of methods of deter-mining nucleic acids in biological materials.16 In the field of water pollu-tion there has been a review of the literature of 1960, including a surveyof analytical methods,l7 and a comparison of methods for determiningchlorine. 1*The Harvard method of determining atomic weights, involving titrationof halides with silver nitrate, has been critically reviewed by A. F. Scott,lgwho points out conditions under which the nephelometric end-point mayhave involved small errors.Difficulties in applying and assessing the value and limitations of statisti-cal methods have been appreciated by Pantony 20 in a chemist’s introduc-tion to statistics, theory of error, and design of experiment.Lewin hasdiscussed variations and errors in experimental investigations 2 1 under theheadings of general causes, compromise errors, insufficient formulations andinaccurate assumptions, limitations of chemical tools and techniques, andpersonal and characteristic errors. Following a symposium on the qualityof observations, papers have been published 22 on the meaning and evalua-tion of precision and accuracy, and the analysis of planned experiments.To facilitate comparisons of performance of analytical methods, definitionsof precision and limit of detection on a uniform basis have been discussed 23with emphasis on the need for including information on behaviour of blankdeterminations.Problems of blanks in the determination of trace elementshave been reviewed,24 and complications in determining errors and con-fidence limits of indirect analyses, due to difficulties in calculating thenumber of degrees of freedom, are discussed by Gorli~h.2~ A further pleais made by Veibel 26 to express analytical results in terms of ‘‘ molecularindices ” instead of, for example, “ acetyl value,” whereby a clearer deduc-tion of structural forniulz may be made.3. Basic operations and apparatusThe operations and apparatus described here are those common to aExcept for some notorious materials, and in very precise work, errorsvariety of analytical methods.l4 E.D. Chilwell and G. S. Hartley, Analyst, 1961, 86, 148.l5 Joint Mercury Residues Panel, Analyst, 1961, 86, 608.l6 W. C. Hutchison and H. N. Munro, Analyst, 1961, 86, 768.l i Research Committee, Water Pollution Control Federation, J . Water Pollut.leM. C. Rand and J. V. Hunter, J . Water Pollut. Control Fed., 1961, 33, 393.19A. F. Scott, Analyt. Chem., 1961, 33 (9), 2 3 ~ .2o D. A. Pantony, The Royal Institute of Chemistry, Lecture Series 1961, No. 2;J . Roy. Inst. Chem., 1961, 85, 411.21 S. Lewin, Lab. Practice, 1961, 10, 99, 162, 363, 474, 556.22 R. B. Murphy, Muter. Res. and Stand., 1961, 1, 264; W. J. Youden, ibi&., p. 268;W. S. Connor, ibid., p. 272; M.E. Terry, ibid., p. 273.23A. L. Wilson, Analyst, 1961, 86, 72, 272.2 r M . Kniiek and J. Provaznik, Chem. Listy, 1961, 55, 389.25P. Gorlich, 2. analyt. Chem., 1961, 179, 266.4 6 S. Veibel, Chim. analyt., 1961, 43, 189.Control Fed., 1961, 33, 445400 ANALYTICAL CHEMISTRYin weighing due to accumulation of electrostatic charges are not commonin British climates. In many countries, and in artificially dry atmospheres,however, they can be serious. By weighing the material inside a thin-walled metal tube, these errors have been overcome in the case of a chargedpolyethylene rod weighed on a microchemical balance ;27 this may havewider application. A statistical appraisal of various contributions to theover-all precision of pipette usage, and an investigation into the effects ofvarying the technique of delivery, have been made by Dean and Herring-shaw.28 Results obtained in a series of controlled experiments are in verygood agreement with the effects calculated, and show that with carefultechnique the largest error is in setting the meniscus to the mark.The studyof variables has enabled a recommended procedure to be made for obtainingthe highest precision under ordinary conditions of use.Small liquid samples may be dried speedily and without bumping byplacing them beside the desiccant in a closed vessel fitted with a paddle toagitate the air;29 contamination of one volatile sample by another mustbe avoided.An improvement is described 30 in the electrolytic hygrometer of Keidel 31for measuring traces of water in gases; the absorbing surface is an externalone and is readily removed for cleaning.The preparation of standard mix-tures of gases for calibration purposes is facilitated by a simple apparatuscomposed of calibrated glass syringes and a football bladder. An easilyconstructed lock has been described for introducing solid samples into ahigh-vacuum system. 33A method for constructing multi- junction thermopiles from fine wireenables piles of over 80 junctions to be readily assembled.34 An automaticmelting point recorder, dependent on the movement of a thermocouplepiston supported by the unmelted solid, gives quick results and does notrequire critical control of heating rates.a5 The boiling point of a drop ofliquid may be obtained by an improved Siwoloboff method,36 agreementwithin 1" of the literature value being obtained for a large number ofsamples.A new indicator, benzaldehyde p-nitrophenylhydrazone, has beendescribed 37 for the pH range 11-12, having the yellow hydrazone formbelow pH 11.3 and the red anionic form above pH 11-7.A pH standardfor blood and other fluids in the range 7-8 has been obtained from solutionsof potassium and sodium hydrogen phosphates;38 its values are listed from0" to 50'. By fitting an adapter unit to a pH meter, its sensitivity can be27 Tetsuo Mitsui and Keikichi Yoshikawa, Mikrochim. Acta, 1961, 527.28 G. A. Dean and J. F. Herringshaw, Analyst, 1961, 86, 434, 440.29H. G. Wager, Analyst, 1961, 86, 266.30E. Barendrecht, Analyt.Chim. Acta, 1961, 25, 402.31 F. A. Keidel, Analyt. Chem., 1959, 31, 2043.32 J. Lacy and K. G. Woolmington, Analyst, 1961, 86, 547.33A. Parker, Analyst, 1961, 86, 550.34 C. A. Glover and R. R. Stanley, Analyt. Chem., 1961, 33, 477.35 L. F. Berhenke, Analyt. Chem., 1961, 33, 65.36 C. Karr, jun., and E. E. Childers, Analyt. Chem., 1961, 33, 655.37 R. O'Connor, W. Rosenbrook, jun., and G. Anderson, Analyt. Chem., 1961, 33,3eV. E. Bower, M. Paabo, and R. G. Bates, Clin. Chena., 1961, 7, 292.1282CARTWRIGHT, WESTWOOD, AND WILSON 401increased to give one pH unit for full-scale deflection on an auxiliary meter 39without detectable drift during a titration.The general equipment and techniques used in ultramicrochemicalmanipulations have been discussed, and potentiometric and amperometrictitrations 40, *1 and chromatographic separations and electrolytic deter-minations 41 have been carried out on this scale.-4. Qualitative analysisInorganic.-Interference in systematic cation analysis by the thio-sulphate ion, which on acidification causes precipitation of sulphides andsulphates as well as sulphur, is resolved by a scheme by W.F. Jones 42 whoselectively extracts from the precipitate first lead, then copper and arsenic,followed by silver and mercury, with provision for detecting insolublesulphates. Thioformanilide has been claimed 43 to be better than thioacet-amide for precipitating sulphides in qualitative analysis, in giving morecomplete precipitation of cadmium, tin(Iv), and lead.A scheme for system-atic identification of calcium, strontium, and barium 44 involves solutionof the perchlorates in acetone, precipitation of barium with nitric acid,followed by chromate, and separation of calcium from strontium by extrac-tion with butanone-nitric acid-acetic acid-acetic anhydride. The co-precipitation of cobalt with aluminium-group hydroxides in qualitativeanalysis has been examined by using cobalt-60 tracer, and was found tobe most serious with chromium ; in semimicro-analysis, precipitation of thehydroxides by the homogeneous method using urea is advocated.45Among procedures for the detection of a number of different ions,Stewart 46 uses a solution of myristic acid in light petroleum applied to thesurface of a dilute solution in a shallow trough. The reagent forms a uni-molecular film which acts as a cation collector, and by compressing the filmwith a barrier the cations may be transferred to a filter-paper strip for detec-tion by suitable reagents.Sensitive and selective colour reactions are used 47to detect calcium, copper, zinc, cobalt, nickel, and palladium (alone amongthe platinum metals) by reaction with a number of azoxy-derivatives ofpolydentate chelating agents. The colour reactions of metals and offluoride with nitrosochromotropic acid have been investigatedY48 and testsare described for copper, cobalt, nickel, and palladium; fluoride is detectedindirectly. A number of bivalent cations which form complexes with 2-hydroxynaphthaldehyde can be identified in low concentration by thecrystal forms obtained.49Among the many methods published for det,ection of individual cations39H.Jackson, Analyst, 1961, 86, 76.4 0 W. Helbig, Z . analyt. Chem., 1961, 182, 15.41 I. P. Alimarin and M. N. Petrikova, Talanta, 1961, 8, 333.42W. F. Jones, Milcrochim. Acta, 1961, 214.43M. B. Antia, R. C. Arora, and R. P. Bhatnagar, Analyst, 1961, 86, 202.44P. Luis, Mikrochim. Acta, 1961, 529.45P. H. Bailey and R. W. C. Broadbank, Analyst, 1961, 86, 485.4sF. H. C. Stewart, Chem. and Id., 1961, 1064.47V. M. Dziomko and K. A. Dunaevskaya, Zhur. analit. Khim., 1960, 15, 661.‘ t ~ Sachindra Kumar Datta and Sachindra Nath Saha, iMikrochim. Acta, 1961, 361.4e S. I. Gusev, V. I. Kumov, and Z. A.Bitovt, Zhur. analit. Khim., 1960, 15, 746402 ANALYTICAL CHEMISTRYand anions is the detection of boron in silicate ores by grinding them withquinalizarin and then adding a drop of sulphuric acid;50 for larger quantitiesof boron a blue colour develops in the cold, and for smaller quantities onheating. Highly coqdensed phosphates can be detected and separated 51with no reaction from mono-, di-, and tri-phosphates and trimetaphosphates,or from silicates, by precipitation with cinchonine sulphate. Chromate maybe detected in dry material in the presence of dichromate and vice versa.52A method for detection and semiquantitative determination of uranium 53 isbased on the intense fluorescence in ultraviolet light of uranyl ion adsorbedon a silica-gel column.A stable red complex of cobalt, claimed 54 to bespecific, is formed with the p-nitrophenylhydrazone of 3-isonitrosopentan-2-one. Other reagents investigated for detection of cobalt are the p-nitro-phenylhydrazone of pyruvaldoxime 55 and, for very small quantities, thetiron-orcinol-hydrogen peroxide and other systems 56 which are stronglycatalysed by cobalt ions; trace amounts of osmium can similarly be detectedby catalysis of oxidations by hydrogen peroxide and by potassium chlorate.57Ruthenium(m) reacts with p-phenylenediamine, but not with the ortho- andmetcc-isomers, to give a violet colour which turns brownish-black;58 this canbe used as a test for either the metal or the reagent.Organic.-The detection of elements in organic compounds has beendiscussed.59 A new and very sensitive test for nitrogen,60 which gives posi-tive results below the level of the Lassaigne test, depends on conversion ofthe cyanide produced by sodium fusion, first into cyanogen chloride withchloraniine T, and then, by reaction with dimedone in pyridine, into poly-methine dyes.Of the very large number of published tests for the identification ofgroups of compounds and individual compounds, only a selection of themore generally useful or interesting ones can be included.Spot tests aregiven for a number of unrelated compounds 61 and for others using detectionin the gaseous phase of products formed by reaction with Devarda's alloyand Raney nickel. 62 Begemann discussed the identification of alcohols,sulphides, and carbonyl compounds e3 present in complex mixtures by forma-tion of derivatives and separation by paper chromatography.Three tests are given for detecting and distinguishing organic peroxides.64Detection of small quantities of p-cresol by coupling with diazotised p-nitro-50 E. P. Ozhigov, V. S. Lozinskaya, and A. L. Krasnitskaya, Zhur. analit. Khim.,1961, 16, 315.51 C. Riess, 2. analyt. Chenz., 1961, 179, 358.52W. F. Jones, Mikrochim. Acta, 1961, 88.53Z. sulcek, J. Michal, and J. Doleial, Chemist-Analyst, 1961, 50, 13.54V. D. Anand, Mikrochim. Acta, 1961, 650.55V. D. Anand, Chemist-Analyst, 1961, 50, 44.56 J. Bogn6.r and 0. Jellinek, Magyar Kim. Folydimt, 1961, 67, 100, 103.57 J. BognAr and S. S&rosi, Magyar Kkm. Folydirat, 1961, 67, 193, 198.'j8Anil K.Mukherji, Mikrochim. Acta, 1961, 1.59 W. I. Stephen, Ind. Chemist, 1961, 37, 86; Chem. Weekblad, 1961, 57, 273.6oA. Sp6v&k, V. Kratochvil, and M. VeEeFa, Coll. Czech. Chem. Cmm., 1961, 26,61 F. Feigl, D. Goldstein, and D. Haguenauer-Castro, 2. analyt. Chem., 1961,178,419.62 F. Feigl, AnaZyt. Chem., 1961, 33, 1118.63P. H. Begemann, Chem. Weekblad, 1961, 57, 293.64 G. H. Foxley, Analyst, 1961, 86, 348.887CARTWRIGHT, WESTWOOD, AND WILSON 403aniline and treatment with magnesium oxide, giving a blue colour, is notinterfered with by the other isomers or by phen01,6~ but resorcinol and someother compounds behave similarly. Tests are described for the detectionof resorcinol, quinol, and catechol, each in presence of a large excess of theothers ;66 neither the trihydroxybenzenes nor di- and tri-aminobenzeneinterfere. A number of copper-substituted pyridines have been comparedas reagents for organic acids 6 7 by spot tests, extractive tests, or micro-scopic examination of crystalline products.For the characterisation ofaldehydes in the presence of ketones, (-J-)- 1,2-dianilino-l,2-diphenylethanegives derivatives with sharp melting points.68 Ketoses may be distinguishedfrom aldoses by the ultraviolet fluorescence shown when their spots, sepa-rated by chromatography, are treated with sulphosalicylic acid. Chroma-tographed spots of glycerides may be distinguished by periodateSchWsbase reagent, with which diglycerides react at once, while monoglyceridesrequire prior decomposition with, e.g., hydro~ylamine.7~ A spot test form-nitroaniline, using phenylhydrazine hydrochloride, is claimed to bespecific.71 Spot-test detection and colorimetric determination of about100 aromatic amines and imino hetero-aromatic compounds 72 uses S-methyl-2-benzothiazolinone hydrazone as reagent. Detection is possible of each ofthe phenylenediamine isomers in presence of the 0thers,~8 and piperidinecan be detected by a spot test in the presence of piperazine and vice v e r s c ~ . ~ ~Reactions of tetraphenylborate ions can serve as a method of preparing use-ful derivatives of some hydroxyarylamines and hydroxyhetero( N ) hydro-c a r b o n ~ , ~ ~ as well as in detecting the reagent. Chloropicrin can be detected,the method being applicable to air samples, by reaction with bromide-cyanide, pyridine, and aniline hydrochloride, applied successively or inadmixture.76A number of spot tests have been described for arylsulphinic acids.77A criticism of methods for the identification of surface-active agents in food-stuffs 78 has been criticised in turn.795. Methods of separationSolvent Extraction.-Separation of metals by selective extraction of theircompounds, or more usually their complexes, into organic solvents continues65 F. Feigl and V. Anger, Analyt. Chem., 1961, 33, 89.66T. S. Ma and A. Hirsch, Chemist-Analyst, 1961, 50, 12.67A. Sa and D. B. Budzko, Rev. ASOC. bioquim. argentina, 1960, 25, 103.6 8 R . Jaunin and J.-P. Godat, Helv. Chim. Acta, 1961, 44, 95.68 E.S. Rorem, Analyt. Biochem., 1960, 1, 218.70B. F . C. Clark, J . Chromatog., 1961, 5, 368.71 F. Feigl and V. Anger, 2. analyt. Chem., 1961, 182, 13.72 E. Sawicki, T. W. Stanley, T. R. Hauser, W. Elbert, and J. L. Noe, Analyt. Chem.,73 A. Hirsch, S. Fishman, M. Goldberg, M. Ottensoser, and M. Schachnow, Chemist-74F. Feigl, Chemist-Analyst, 1961, 50, 15, 18.76R. Neu, Mikrochim. Acta, 1961, 32.78H. Drtecke and R. Kraul, 2. analyt. Chem., 1961, 178, 412.7 7 F . Feigl, D. Haguenauer-Castro, and E. Libergott, Mikrochim. Acta, 1961, 595.78 W. Ciusa, and G. Brtrbiroli, Boll. Lab. Chim. Provinciali, 1961, 12, 30.79 F. Muntoni, Boll. Lab. Chirn. Provir?.ciaEi, 1961, 12, 215.1961, 33, 722.Analyst, 1961, 50, 7 404 ANALYTICAL CHEMISTRYto attract many workers.Earlier papers set a high standard in thorough-ness of investigation, and this has generally been maintained. The workreported here has been selected from a wide field to demonstrate develop-ments in the scope and potentialities of the method, which finds its mostuseful application in the separation of small quantities of a particular ele-ment, which can then often be determined directly by spectrophotometry.of the extraction of 57 metals asquaternary amine (propyl, butyl, and hexyl) complexes into isobutyl methylketone from four acid and one alkaline media. Many separations withanalytical possibilities in both radiochemical and general fields have beentabulated. The behaviour of the acetylacetonates of 18 metals on extrac-tion into chloroform at varying pH has been investigated,81 and correlatedwith the ionic character of the metals. The use of dithizone as an extractantfor metals has been briefly discussed.82 A study has been made of the extrac-tion of copper-64 from aqueous hydrochloric acid solution into a chloroformor carbon tetrachloride solution retained on silica gel, the results suggestingthe possibility of adopting solvent-extraction to work on the column prin-ciple.83The effect of quaternary ammonium salts on the 8-hydroxyquinolineextraction of magnesium has been studied a4 and a method is proposed whichseparates magnesium from calcium, strontium, and barium. Further thio-nine derivatives have been studied 85 for the extraction of boron, and satis-factory combinations of extractant and solvent have been discovered.Small amounts of aluminium may be extracted by 8-hydroxyquinoline fromsolution of siliceous materials, after first extracting iron and titanium.86Extraction of iodo-complexes of indium and thallium into ether solution isused as a preliminary to the spectrographic determination of the metals inrocks. 87 A number of solvents and solvent mixtures were investigated forthe separation of phosphate from arsenate ;*8 butanol-chloroform was themost effective, but clean separation was not possible in one extraction. Theextraction of arsenic(1n) from hydrochloric acid solution into a benzenesolution of catechol has been re-exarnined,ag and it was found that aboveSN-acid, catechol has little effect, and effective separation of arsenic fromantimony and bismuth is obtained with benzene alone.Extraction ofiodide using cadmium and a tributyl phosphate-butyl methyl ketonesolvent is an example of anion separation when suitable complexes canbe formed.Yttrium can be quantitatively separated from lanthanum and ceriumA very full study has been made80 W. J. Maeck, G. L. Booman, M. E. Kussy, and J. E. Rein, Analyt. Chem., 1961,81 Tsunenobu Shigematsu and Masayuki Tabushi, Bull. Inst. Chem. Res., Kyoto82 H. Freiser, Chemist-Analyst, 1961, 50, 62.83T. B. Pierce, AnaZyt. Chim. Acta, 1961, 24, 146.8 4 s . J. Jankowski and H. Freiser, AnaZyt. Chem., 1961, 33, 776.S S L . Pasztor and J. D. Bode, Analyt. Chim. Acta, 1961, 24, 467.seF.VlbEil and V. ZBtka, Chem. prumysl, 1961, 11, 139.87R. R. Brooks, Analyt. Chim. Acta, 1961, 24, 456.a8H. H. Ross and R. B. Hahn, Talanta, 1961, 7, 276.89 H. C. Beard and L. A. Lyerly, AnaZyt. Chem., 1961, 33, 1781.OOP. W. West and A. S. Lorica, Analyt. China. Acta, 1961, 25, 28.33, 1775.Univ., 1961, 39, 35CARTWRIGHT, WESTWOOD, AND WILSON 405by extraction from nitric acid solution by tributyl pho~phafe,~~ the methodbeing applicable to the determination of strontium-90 which decays to giveyttrium. The extraction of zirconium into xylene as the Z-thenoyltrifluoro-acetone complex has been improved 92 to reduce variability of recovery.It has been suggested 93 that the extraction of zirconium by tributyl phos-phate owes its effectiveness to the presence of dibutyl phosphate.Tributylphosphate has been used to extract vanadium( v) from hydrochloric acidsolution, and interferences have been studied.94 Effective separation ofiron from vanadium and chromium can be achieved by extracting ferricchloride with isopfopyl ether.95 Technetium and rhenium can be separatedfrom uranium by extraction with pyridine from sodium carbonate solution.96The extraction of uranium complexes with dibenzoylmethane into carbontetrachloride, chloroform, and benzene has been studied 97 and comparedwith results on use of acetylacetone and benzoylacetone. Successive extrac-tion of copper, iron, and cobalt forms the basis of a method for their deter-mination in electrolytic Osmium can be determined in uranylsolutions following oxidation to osmium tetroxide and extraction intochloroform. 99A method which is specific for plutonium depends on the extraction intois0 bu t yl met h y 1 ketone of the t et r aprop y lammonium nit rate-plut onium ( VT )complex from an acid-deficient salting solution.100 A selective method forcopper l01 is based on reduction with ascorbic acid to copper(1) and extrac-tion with triphenyl phosphite in carbon tetrachloride; gold can be extractedinto chloroform from chloride solution with tetraphenylarsonium chloride.l 0 2Solvent extraction can usefully be applied to isotopic dilution analysis, asin the case of zinc.lO3As well as its usual application to the separation of a metal, solventextraction can be employed to determine the extracting agent.An exampleof this is the improvement in the method for determining amines lo4 byextracting the amine-cobalt thiocyanate complex into pentyl alcohol-kerosene mixture.Solvent extraction has also been discussed as a general method forrecovery, purification, and identification of drugs and their metabolic pro-ducts, lo5 with particular reference to barbiturates.91 A. S. Goldin and R. J. Velten, Analyt. Chem., 1961, 33, 149.9zS. F. Marsh, W. J. Maeck, G. L. Booman, and J. E. Rein, Analyt. Chem., 1961,93 R. 3'. Rolf, Analyt. Chem., 1961, 33, 149.9p Santosh K. Majumdar and Anil K. De, Analyt. Chenz., 1961, 33, 297.95 G. A. Dean and J. F. Herringshaw, Analyst, 1961, 86, 106.S. J. Rimshaw and G. F. Malling, Analyt.Clzern., 1961, 33, 751.97 V. MouEka and J. Star9, Coll. Czech. Chem. Cornm., 1961, 26, 763.O 8 S. E. Kreimer, A. V. Stogova, and A. S. Lomekhov, Zavodskaya Lab., 1961, 27,gs G. Goldstein, D. L. Manning, 0. Menis, and J. A. Dean, Talanta, 1961,7,296,301.loo W. J. Maeck, M. E. KUSSY, G. L. Booman, and J. E. Rein, Analyt. Chem.,lolT. H. Handley and J. A. Dean, Analyt. Chem., 1961, 33, 1087.lo2 J. W. Murphy and H. E. Affsprung, Analyt. Chem., 1961, 33, 1658.lo8 J. Starjr and J. RfiiiEka, Talanta, 1961, 8, 296.lMP. J. Lloyd and A. D. Cam, Analyst, 1961, 86, 335.lo5M. T. Bush, Microchern. J., 1961, 5, 73.33, 870.386.1961, 33, 998406 ANALYTICAL CHEMISTRYChromatography.-The term is, as in the last Report, limited to liquid-phase separations on columns, paper, gels, or thin films, and separate con-sideration is given to electrophoresis, ion-exchange and gas chromatography.Except in the field of thin-film chromatography, the bulk of the considerablevolume of published work has concerned either modifications to improveexisting applications, or new applications of established techniques, few ofwhich can be reported.A survey has been given106 of the varioustypes of liquid-liquid and solid-liquid chromatography, with discussion ofvarious methods of detecting the solute.Theoretical condideration has beengiven to the mechanism and efficiency of linear chromatographic processesand has been applied to analytical separations of solutes 107 and discussedin terms of the strength and distribution of adsorption sites, with thermo-dynamic treatment of results obtained with series of organic compoundsusing several solvents.lo* Procedures for activating and standardisingsilica have been published which allow the reproducible selection of any of10 grades of activity.lo9 A novel stationary phase is composed of fragmentsof rubber swollen by toluene, used with toluene as mobile phase;llO tetra-fluoroethylene has been used as column medium for separation of lipids.ll1Devices have been described for automatic fraction sampling for analy-sis,112 for automatic titration of eluted organic acids,113 and for continuousspectrophotometric monitoring of eluates.114, 1 1 5 9 116No report is given of applications to particular separations; they con-tinue to be concerned largely with separations of ionic species by means ofmixed organic solvents, and of a wide variety of organic compounds, in bothcases followed by identification and often determination using colour reac-tions or spectrophotometry.Paper chromatography. A review has been published of methods andapparatus used in quantitative radio paper chromatography.117 In deter-mining carbon-14 in paper chromatograms, it is recommended that the spotsbe scanned from both sides of the paper and the results averaged.ll8 Theinfluence of pH on the RF values of organic acids, by use of neutral solvents,has been investigated;llg the results are interpreted in terms of the effect ofthe substituents on the dissociation constant of the acid group.A method has been devised for .applying solutions rapidly to paper toform a spot via a cotton thread passed through the paper,lZ0 and a thin106 G.Dijkstra, Chem. Weekblad, 1961, 57, 189.107P. C. Haarhoff and V. Pretorius, J . S . African Chem. Inst., 1961, 14, 22.1O8L. R. Snyder, J . Chromatog., 1961, 5, 430; 6, 22.lo9 R. Hernandez, R. Hernandez, Jun., and L. R. Axelrod, Analyt. Chem., 1961, 33,1lOP. I. Brewer, Nature, 1961, 190, 625.111A. C. Arcus and G. G. Dunckley, J . Chromatog., 1961, 5, 272.112 R. J. Rowlands, J . Chromatog., 1961, 6, 58.llaO. Forsander and P. Neuenschwander, J . Chromatog., 1961, 5, 515.l14N. G. Anderson, Analyt. Chem., 1961, 33, 970.115 F. Alderweireldt, J . Chromatog., 1961, 5, 98.116 J. H. Young, Analyst, 1961, 86, 520.l17F.Pocchiari and C. Rossi, J . Chromatog., 1961, 5, 377.ll8H. J. M. Hansen, Acta Chem. Scad., 1961, 15, 670.ll0A. Panek and R. Leibsohn, J . Chromatog., 1961, 5, 308.120D. P. Dearnaley and R. M. Acheson, J . Chromatog., 1961, 5 , 452.Column chroma.tography.370CARTWRIGHT, WESTWOOD, AND WILSON 407reproducible line of solution can be applied by using a hypodermic syringecontrolled mechanically.121 Devices for evaporating solvent during appli-cation of the sample, by means of a stream of nitrogen,122 and for air-dryingstrip chromatograms by using glass Buchner funnels, 123 have been described.Many separations of groups of cations by paper chromatography, fol-lowed generally by spot-test identification, have been carried out.Mer-cury(n), lead, bismuth, copper, and cadmium have been separated by meansof hydrochloric or sulphuric acid media.124 Acetates of iron(m), nickel,cobalt, zinc, silver, cadmium, mercury, lead, and uranium(m) can be sepa-rated by two-dimensional elution with acetone-acetic acid and ethanol-acetic acid.125 Ascending elution with 60% ethanol in presence of varyingamounts of citrate, tartrate, and oxalate serves to separate mixtures of upto 5 of 10 common metals.126Beryllium is separated, and determined by a colour reaction comparedwith standards, by ascending elution with a water-hydrochloric acid-ethylmethyl ketone solvent on paper previously impregnated with EDTA.12'Tin is similarly determined by using butanol-hydrochloric acid-waterseparation on plain paper.l28 Copper and zinc can be isolated separatelyas their 8-hydroxyquinolates with butanol-hydrochloric acid-water oncircular paper, followed by titrimetric determination with EDTA.129Separation of copper, nickel, and cobalt after treatment with excess ofthiocyanate was achieved l30 by using ammonia-pyridine-alcohol solvents.Rapid trace analyses of phosphate mixtures 131 and pyrophosphates andpolyphosphoric esters 132 have been described.In the organic field, paper chromatography continues to be widely usedto isolate small quantities of pure compounds for identification by colourreactions or determination by spectrophotometry.Classes of compoundshave been investigated ; separation and identification of 3,5-dinitrobenzoylderivatives of a large number of alcohols, glycols, polyoxyethylene glycols,phenols, thiols, and amines by using various solvents and papers have beendescribed.133 RF values are given 134 for 50 aldehydes and ketones aftercondensation with cyanoacetic acid hydrazide, by means of chloroform onimpregnated paper.Diglycerides are separated from and detected in thepresence of monoglycerides, 70 and mixed sugars in fermenting liquors areseparated by rapid horizontal paper chromatography a t 60 O for identifica-tion and determinati0n.l3~ In the presence of monobasic acids, which move121S. W. McKibbins, J. F. Harris, and J. F. Saeman, J . Chromatog., 1961, 5, 207.ln2V. H. Booth, J . Chromatog., 1961, 6, 95.lZ3 J. Goldyn, J . Chromatog., 1961, 5, 372.124V. K.Mohan Rao, J . Sci. Ind. Res., India, B, 1961, 20, 109.125H. S. R. Barreto, R. C. R. Barreto, and I. P. Pinto, J . Chromatog., 1961, 5, 5.la6 E. J. Singh and Arun K. Dey, Analyt. Chim. Acta, 1961, 24, 444.12' D. Ader and A. Alon, Analyst, 1961, 86, 125.128 S. Fisel, H. Franchevici, and Gh. Bilan, Rev. Chim. ( h a d . R.P.R.), 1961,6, 175.leST. D. Miles, A. C. Delasanta, and J. C. Barry, Analyt. C h m . , 1961, 33, 685.130M. R. Verma and P. K. Gupta, Current Sci., 1961, 30, 10.lS1 R. H. Kolloff, Analyt. Chem., 1961, 33, 373.132 P. L. Ipata and R. R. Manaresi, Boll. SOC. ital. BioE. sper., 1961, 37, 464.133 J. Gaspmi6 and J . BoreckJi, J . Chromatog., 1961, 5, 466.134 J. Franc and G. Celikovsk8, ColZ. Czech. Chem. Comm., 1961, 26, 667.135 J. B.Himes, L. D. Metcalfe, and H. Ralston, AnaZyt. Chem., 1961, 33, 364408 AN AL Y T I C AL CHEMISTRYwith the solvent front, C6-cl2 dibasic acids can be separated and identi-fied.l36 A review has been published137 of the chromatographic separa-tion, both column and paper, of porphyrins and metallo-porphyrins.Thin-layer chromatography. Chromatography on glass plates spreadwith thin layers of adsorbents such as silica gel, alumina, or kieselguhr,generally mixed with a binding material, has advantages in compactness,rapidity of equilibration and development, sharpness of separation, andscope for application of identifying reagents. Although reproducibility maynot be so high as with paper, applications of the technique have been growingrapidly.A review 138 deals with its development, methods, and typicaluses, and another covers recent progress. 139 Separations of lithium, sodium,potassium, and magnesium, 140 and applications to vitamin identification,l41are examples of its uses in inorganic and organic analysis.Electrophoresis.-High-voltage paper electrophoresis using potentials ofmore than 50 v per cm. and energy input of 1 w per sq. cm., dissipated byaluminium heat-exchangers, has been described 142 for rapid separationswith high resolution of complex mixtures of compounds of low molecularweight. Direct recording of optical density of closely spaced bands obtainedby paper electrophoresis is possible by using an apparatus 143 which passesthe strip, soaked in paraffin oil, a t constant speed across a narrow lightbeam.Suitable treatment of starch gel after electrophoresis and staining cantransform it into a transparent flexible film which can be used for directphotometry.144 Polymerised acrylamide, used as a gel, gives a similarThe behaviour of some acids and salts in altering the pH, often radically,during paper electrophoresis has been studied, and its effects on inorganicseparations have been discussed.146 The addition of phenol has beenfound 147 to improve the separation of potassium, rubidium, and czsium bypaper ionophoresis.Continuous electrophoretic separation of radioactivecadmium and indium has been described.148Paper electrophoresis has been used to separate glycine and permit itsdetermination by ninhydrin in protein hydrolysates, 149 and to separatehzmoglobin A, from blood samples for spectrophotometric determina-tion.150 It has also been used in the separation and characterisation ofa number of local anzsthetics.151fiim.145136 J.L. Occolowitz, J . Chromatog., 1961, 5, 373.137 J. E. Falk, J . Chromatog., 1961, 5, 277.138 E. G. Wollish, M. Schmall, and M. Hawrylyshyn, Analyt. Chem., 1961, 33, 1138.139 E. Demole, J . Chromatog., 1961, 6, 2.14oH. Seiler and W. Rothweiler, Helv. Chim. Acta, 1961, 44, 941.141 E. Nurnberg, Apoth.-Ztg., 1961, 101, 268.142 D. Gross, J . Chromatog., 1961, 5 , 194.143 Anon., Lab. Practice, 1961, 10, 287.144 J. Groulade, J. M. Fine, and C. Ollivier, Nature, 1961, 191, 72.145 S. Raymond and Y.-J. Wang, AnaEyt.Biochem., 1960, 1, 391.146 Z. Szponar, Chem. Analit., 1961, 6, 187.147 T. Pompowski, J. Kowalczyk, and I. Siemianowska, Chem. AnaZit., 1961, 6, 393.l48Z. Konrad-Jakovac and Z. PuEar, Croat. Chem. Acta, 1961, 33, 33.149 J. Saint-Blancard and J. Storck, Ann. pharm. frang., 1960, 18, 711.l5OR. N. Ibbotson and B. A. Crompton, J . Clin. Path., 1961, 14, 164.15lV. Jokl and V, Sukupov&-Kolkov&, Cesk. Farm., 1961, 10, 197CARTWRTCJHT, WESTWOOD, AND WILSON 409Ion Exchange.-Ion-exchange methods continue to be generally used forremoving interfering ions from solution before applying a particular methodof determination, as, for example, in the treatment of mineral solutions forthe flame-photometric determination of copper. 152 Treated resins are alsoused to fix, and then recover, particular ions, as in the separation of lead ona sulphate-treated anion exchanger, followed by elution with sodiumhydroxide solution.153 Attention has been given to the use of paperimpregnated with the ion exchanger ; zirconium phosphate,154, 155 hydratedzirconium oxide, and zirconium tungstate 156 have been used, as well aslong-chain tertiary amines such as tri-n-octylamine.157 Experiments havesuggested 158 that sodium halide mixtures may be separated by placing thesolid halides on a sodium-form resin column and elution with 80% aqueousacetone.Salting-out chromatography, which is the separation of non-electrolyteson ion-exchange resins with salt solutions as eluents, has been reviewed anddiscussed l 5 9 from the point of view of theory and application. A novelseparation method, called ligand exchange, has been described 160 in whichmetal ions such as copper-(I) or -(II), nickel, silver, or cobalt(m) are held ina column of ion-exchange resin.hydric alcohols, olefins, amino- and organic-acid anions are strongly ad-sorbed, since they form strong complexes with the metals.Selective dis-placement of ligands allows sharp separation of very small quantities to beachieved; little resin need be used because of the strength of the complexformation.Gas Chromatography.-When mixtures, simple or complex, of materialswith moderate vapour pressures are to be separated, many techniques whichhave served their day have given way to gas chromatography. This isreflected in the continuing very large number of papers in which the methodis used for identification, for direct determination by ratio of peaks or bycomparison with standards, or as a preliminary to other methods of deter-mination.Chovin has reviewed 161 the derivation and applications of separationfactors, retention indices, and effects of adsorption a t the gas-liquid inter-face.A review of applications of gas chromatography162 contains 349references. Precision and accuracy of the method have been investi-gated 163 by repeated separation of a propane-butane mixture. The choiceof solid supports 164 and of solvents 1e5 has been studied. General rules forLigands such as ammonia, amines, poly- .lS2 W. G. Schrenk, K. Graber, and R. Johnson, Analyt.Chenz., 1961, 33, 106.153 M. Ziegler, 2. undyt. Chenz., 1961, 180, 1 .154 G. Alberti and A. Conte, J . Chronaatog., 1961, 5 , 844.155 M. J. Nunes da Costa and M. A. S. Jerhimo, J . Chromatog., 1961, 5, 456.156 J. P. Adloff, J . Chrcmmtoq., 1961, 5, 366.15’ C. Testa, J . Chronmtog., 1961, 5, 236.158 G. L. Starobineta and S. A. Mechkovskii, Zhur. analit. Khim., 1961, 16, 319.159 W. Rieman, 111, J . Chem. Educ., 1961, 38, 338.160 F. Helfferich, Nature, 1961, 189, 1001.161 P. Chovin, Bull. Soc. china. France, 1961, 875.162 I. G . McWilliam, Rev. Pitre Appl. Chenz. (AustraEia), 1961, 11, 33.163 It. X. Evans and P. G. W. Scott, Natwre, 1961, 190, 710.164 E. M. Bens, Aizulyt. Chenz., 1961, 33, 179.165 D. E. Martire, AnaZyt. Chern., 1961, 33, 1143410 ANALYTICAL CHEMISTRYreducing analysis time are given in a discussion of high-speed gas chromato-graphy.166Lovelock 167 reviews the construction, scope, and application of ionisa-tion detectors.Columns constructed from individual short sections,arranged cylindrically and connected at the ends,168 have advantages in easeof filling, thermostatting in a large Dewar flask, and tapping to give varyinglengths. Circuit details are given for a recording integrator.169 Theeffectiveness of stream-splitters is discussed and a satisfactory design isdescribed. 170 Methods are given for determining gas-chromatographic frac-tions by mass spectrometry,171 chemical reaction,l72 infrared spectro-~ c o p y , ~ ~ ~ , 174 and measurement of radioa~tivity.l7~Improvements have been devised for using gas chromatography in sepa-rating and detecting the permanent gases in general, l~ hydrogen,l77 hydro-gen, nitrogen and oxygen derived from steel and cast iron,178 and impuritiesin chlorine gas.179Materials of low volatility may be identified through their pyrolysis pro-ducts, the chromatogram of which is often specific for the original substance.The technique is particularly applicable to analysis of polymers, and Hewittand Whitham 180 have reviewed the methods employed and have describeda pyrolysis unit which can be attached to a chromatographic column.Otherpyrolysis units have been designed 1 8 1 9 182 and a two-stage gas chromato-graph has been constructed 183 to deal with the products of flash pyrolysisby xenon discharge or carbon arc.In a study of combustion products bygas chromatography lS4 over 20 compounds were separated.Of the many hundreds of applications of gas chromatography to indi-vidual compounds published during the year, mention will only be made ofthe determination of hydrogen cyanide in air samples with a precision andaccuracy superior to those for the usual chemical methods,lE5 and the deter-mination of amino-acids as esters of the N-trimethylsilyl or N-acetylderivatives. lS7166B. 0. Ayers, R. J. Loyd, and D. D. DeFord, Analyt. Chem., 1961, 33, 986.1 6 7 J. E. Lovelock, Analyt. Chem., 1961, 33, 162.1 6 8 s . A. Ryce and W. A. Bryce, Analyt. Chem., 1961, 33, 654.160 A. P. H. Jennings, J . Sci. Instr., 1959, 38, 55.1"JL.S. Ettre and W. Averill, Analyt. Chem., 1961, 33, 680.171E. J. Levy, R. R. Doyle, R. A. Brown, and F. W. Melpolder, Analyt. Chem.,172 R. Rowan, jun., Analyt. Chem., 1961, 33, 658.173 J. Haslam, A. R. Jeffs, and H. A. Willis, Analyst, 1961, 86, 44.174 S. S. Chang, C. E. Ireland, and H. Tai, Analyt. Chem., 1961, 33, 479.176A. T. James and E. A. Piper, J . Chromatog., 1961, 5, 265.176R. A. Landowne and S. R. Lipsky, Nature, 1961, 189, 571.177 P. J. Kipping, Nature, 1961, 191, 270.1 7 8 P . Tyou and A. Hans, Rev. Mttall., 1961, 58, 187.179 J. Lacy and K. G. Woolmington, AnaZyst, 1961, 86, 350.18oG. C. Rewitt and B. T. Whitham, Analyst, 1961, 86, 643.181W. B. Swann and J. P. Dux, Analyt. Chem., 1961, 33, 654.1E2H. Cherdron, L.Hohr, and W. Kern, Angew. Chern., 1961, 73, 215.l a 3 S. B. Martin and R. W. Ramstad, Analyt. Chem., 1961, 33, 982.1a4C. F. Cullis, A. Fish, F. R. F. Hardy, and E. A. Warwicker, Chem. and Id.,lE5 K. G. Woolmington, J . Appl. Chem., 1961, 11, 114.la6K. Ruhlmann and W. Giesecke, Angew. Chem., 1961, 73, 113.15'D. E. Johnson, S. J. Scott, and A. Meister, Analyt. Ghem., 1961, 33, 669.1961, 33, 698.1961, 1158CARTWRIGHT, WESTWOOD, AND WILSON 41 16. Gravimetric and titrimetic analysisGravimetric Analysis.-Although classical gravimetry continues to loseground in the face of instrumental methods, some analysts remain who havenot yet abandoned their crucibles. Some new reagents have been proposed,mainly in the inorganic field, and some established methods have beenre- appraised.Inorganic.Gravimetric and titrimetric methods for the determinationof gold have been surveyed and critically examined,l*8 and a similar examina-tion has been made of the gravimetric methods for the determination ofphosphorus in tungsten ~tee1s.l~~New reagents have been reported for the detection and gravimetric deter-mination of the alkali metals. 5-Benzaminoanthraquinone-2-sulphonic acidis very sensitive to the presence of sodium but is not selective and is unableto tolerate the presence of other alkali metals or the ammoniumOrotic acid yields soluble salts with ammonium and substituted ammoniumbases which precipitate sodium and potassium orotates.lgl NN-Dialkyl-2-hydroxyethylammonium orotates can be used for the gravimetric deter-mination of sodium and potassium in the absence of each other but in thepresence of ammonium ions.Beryllium may be determined by precipitation a t 50-60" and pH 5.5-6.5 with ethanolic N-benzoyl-N-phenylhydroxylamine ; lg2 the precipitatemay be weighed directly or after ignition to oxide.Separation of berylliumfrom iron, aluminium, and titanium may be accomplished by differentialprecipitation.Silicon has been determined in the presence of boron by dehydration ofsilicic acid with glycerol and precipitation with gelatine.lg3 The resultshave been found to be as good as or better than those obtained by conven-tional mineral-acid methods.Small quantities of lead in solution ( 1 4 mg.) may be quantitativelyreduced to the metal by a chromous salt at pH 3-7 and may be filtered offand weighed.lg4A number of carboxylic acids have been used for the precipitation ofthorium;lg5 o-bromobenzoic acid a t pH 3434.2 is useful for the separationof thorium from rare earths.Zirconium may be determined by precipita-tion with 3-acetyl-4-hydroxycoumarin at pH 3.5-7.0, and the same reagentprecipitates titanium lg6 at pH 7-0-9.0. In both cases the precipitates areignited to oxide.A study has been made of the coprecipitation of phosphate with leadlesF. E. Beamish, Talanta, 1961, 8, 85.leg 5. Spauszus, C. Schwarz, and H. J. Weigel, 2. analyt. Chem., 1961, 182, 184.lQoH. S. Gowda, and W. I. Stephen, Analyt. Chim. Acta, 1961, 25, 163.lS1R. Selleri and 0. Caldini, Andyt.Chem., 1961, 33, 1944.lea J. Das and S. C. Shome, Analyt. Chim. Acta, 1961, 24, 37.lQ3L. C. Pasztor, Analyt. Chem., 1961, 33, 1270.lQ4N. T. Vasina, Zhur. analit. Khirn., 1961, 16, 241.lg5 Ch. Bheemasankara Rao, P. Umapathi, and IT. Venkateswarlu, Analyt. Chim.lQ6 A. N. Bhat and B. D. Jain, Proc. Indian Acad. Sci., A , 1961, 53, 147.Acta, 1961, 24, 391412 ANALYTICAL CHEMISTRYmolybdate in the British Standards Institution method for determiningphosphorus in ~tee1.1~7Molybdenum may be precipitated with N-benzoylphenylhydroxyl-amine lg8 and either weighed directly or as oxide after heating to 500-525".The method may be used in the presence of chromium(vI), cobalt(=),nickel( II) , copper( 11) , iron( III) , and vanadium( v) .The determination of cobalt(@ by precipitation as anthranilate and asphosphate has been examined and gravimetric procedures compared withelectrolysis methods.lg9 Of the gravimetric methods only a modificationof the phosphate precipitation gives satisfactory results. The electrolyticmethod gives high results owing to a contaminated deposit.In the determination of the composition of urea-hydrocarboncomplexes urea may be quantitatively precipitated by the addition of asaturated solution of xanthhydrol in methanol ;2O0 the precipitate is weighedafter drying at 100". Three methods for the determination of N-o-bromo-benzyl-N-ethyl-NN-dimethylammonium toluene-p-sulphonate by means ofsodium tetraphenylborate have been examined. 201 The methods consistedof gravimetric, gravimetric followed by a titrimetric determination in non-aqueous solution, and titrimetric in aqueous medium, and were found to giverelative errors of -&0.6%, &0.2%, and &0.7%, respectively.Precipitation from homogeneous solution.The r61e of nucleation in pre-cipitation from homogeneous solution has been discussed following the state-ment by Fischer that the process is one of direct mixing. Haberman andGordon,Zo2 while admitting that this may occur, maintain that it is by nomeans the normal situation, and hold that Fischer's conclusions are notapplicable to many methods of generation of ions in situ. Fischer, whileagreeing that nucleation is not necessarily one of direct mixing, feels thatthere is still sufficient evidence to indicate that this must frequently bethe case.Coprecipitation in some binary sulphate systems has beenstudied. 203The use of hydrazine has been recommended to accelerate the rate ofhydrogen sulphide evolution from thioacetamide solutions. 204 Readily col-lected precipitates of metal sulphides may be obtained by working at 50"and pH 5.5.A study has been made of precipitation at constant pH by using cationrelease from metal-EDTA complexes by oxidation of the metal complexeswith hydrogen peroxide,205 and the method has been applied to the precipi-tation of certain metal phosphates.206The method of Gordon and Firsching for the precipitation of bariumOrganic.lg7 R. B. Heslop and R. Kirby, Analyst, 1961, 86, 134.Is* S. K. Sinha and S.C. Shome, Analyt. Chim. Acta, 1961, 24, 33.lS9 A. G. Foster and W. J. Williams, Analyt. Chim. Acta, 1961, 24, 20.200R. W. Kiser, M. D. Shetlar, and G. D. Johnson, Analyt. Chem., 1961, 33, 314.2e1 I. Gyenes, Magyar Kim. Folydirat, 1961, 67, 162.2ozR. B. Fischer, Analyt. Chem., 1960, 32, 1127; N. Haberman and L. Gordon,%03A. I. Cohen and L. Gordon, Talanta, 1961, 7, 195.204D. M. King and F. C. Anson, Analyt. Chem., 1961, 33, 572.205P. F. S. Cartwright, Analyst, 1961, 86, 688.206 P. F. S. Cartwright, Analyst, 1961, 86, 692.ibid., 1961, 33, 1801; R. B. Fischer, ibid., p. 1802CARTWRIGHT, WESTWOOD, AND WILSON 413chromate at controlled pH has been modified to reduce the time required forprecipitation, and to overcome the need for careful pH contr01.~0~The separation of strontium from calcium and the selective precipitationof strontium sulphate may be achieved by the addition of a solution of mag-nesium sulphate to mixtures of calcium and strontium complexes withEDTA t o displace the strontium.2o8 A similar technique has been appliedby Firsching to the precipitation of barium by displacing the metal fromeither its EDTA or its DCYTA (1,2-diaminocyclohexane-NN"N'-tetra-aminoacetic acid) complex by the addition of magnesium i0ns.~0~ Tetra-fluoroethylene beakers were used to prevent adherence of the precipitate tothe walls of the vessel.Aluminium has been determined as aluminium oxinate by hydrolysis of8-acetoxyquinoline to generate the precipitant in situ,210 and as quinolate bythe volatilisation of acetone from an acetone-water solution.211Niobium oxinate of definite composition has been precipitated by ureahydrolysis in a solution of the metal containing oxalic acid and an excess of8-hydroxyquinoline, 212 and tantalum and niobium have been precipitatedand determined with 3,3',4', 5,7 -pentahydroxyflavanone.Tungsten may be precipitated by the thermal decomposition of solubleperoxytungstates in a nitric acid-hydrogen peroxide solution with less co-precipitation of molybdenum and vanadium.214The precipitation of palladium dimethylglyoximate has been reportedby the generation in situ of dimethylglyoxime from biacetyl and hydroxyl-amine.215 The precipitates were readily filtered, but the separation fromplatinum and nickel was found to be no better than may be achieved byconventional methods.Cobalt has been precipitated by reaction of bivalentcobalt with a mixture of nitrous acid and 2-naphthol to give tervalentcobalt 1 -nitroso-2-naphthoxide, but nickel, copper, and silver interfere. 216Titrimetric Analysis.-This Report is divided according to the class oftitrimetric determination, and reflects the continuing importance of con-tributions to chelatometry, among which are several papers dealing withmore fundamental aspects. Functional-group determinations are againincluded in the section on non-aqueous titrimetry.The theory and practice of titrimetric analysis have beencrit,ically reviewed, and the selection and preparation of primary standardshave been discussed.217 The use of anhydrous sodium carbonate as a stan-dard in acidimetry has been studied and a recommended method has beenproposed for its preparation for this purpose.218General.207 G.Norwitz, Analyt. Chern., 1961, 33, 312.20aL. Ber&k and J. Munich, Coll. Czech. Chern. Comrn., 1961, 26, 276.2osF. H. Firsching, Analyt. Chem., 1961, 33, 1946.210L. C. Howick and W. W. Trigg, Analyt. Chem., 1961, 33, 302.211L. C. Howick and J. L. Jones, Talanta, 1961, 8, 445.21zL. Kosta and M. Dular, Talanta, 1961, 8, 265.213 F. L. Chan, Talanta, 1961, 7 , 253.z14R. Dams and J. Hoste, Talanta, 1961, 8, 664.t l s L . J. Kanner, E. D. Salesin, and L. Gordon, Talunta, 1961, 7, 288.216 A. H. A. Heyn and P. A. Brauner, Talanta, 1961, 7, 281.217 A. Graire, Chirn.Anal., 1961, 43, 53.218 S. J. Cox, W. C . Johnson, E. J. Newman, and J. T. Yardley, Analyst, 1961,86, 4644 14 ANALYTICAL CHEMISTRYBishop and Jennings have continued their work on the use of chlor-amine T with a potentiometric study of the chloramine r-arsenic(m) reac-tioq219 a study of the use of visual indicators in the same reaction,220 andan investigation of the chloramine T-iodate reaction.221A rapid method has been described for the deter-mination of combined ammonia and phosphate in the system diammoniumphosphate and dipotassium phosphate. 222 An alkalimetric method hasbeen used for the determination of phosphoric acid, condensed polyphos-phates being used for masking interfering ions.223 The method depends onthe formation of colourless complexes of sodium hexametaphosphate withcalcium, magnesium, iron, and aluminium which do not interfere with theindicator colour change in alkalimetric analysis.Very small amounts of carbon dioxide may be determined by absorptionin an excess of barium hydroxide solution which is protected from atmo-spheric carbon dioxide by a layer of ~ e n t a n e .~ ~ ~ Results are said to beaccurate within 1.0% and the method may be applied to the determinationof carbon in organic compounds.A study has been made of the iodometric determina-tion of carbon disulphide 225 and attention has been drawn to the importanceof pH control in avoiding low results. The conditions affecting the iodo-metric determination of persulphate in sulphuric acid solution have beenstudied 2z6 and a scheme for the iodometric analysis of chromate, arsenate,periodate, iodate, bromate, and chlorate ions in the presence of one anotherhas been described.227Iodometric methods have been used in the determination of the con-figuration of bridged Diels-Alder adducts.228 endo-Products absorb 99-101% of the theoretical amount of iodine, while exo-isomers do not react.The excess of iodine is titrated with arsenite solution and starch indicator.E’errous ions in ferrous oxalate may be determined by a bromatometrictitration using p-ethoxychrysoidine indicator. 229 Special precautions arenecessary when dissolving the sample to exclude atmospheric oxygen.Persulphate in sulphuric acid solution is hydro-lysed to hydrogen peroxide, the reaction reaching a maximum a t 1 2 .5 ~ -sulphuric acid. Under controlled conditions use can be made of this reac-tion for the determination of persulphate by titration with permanganatesolution. 230Uranium can be determined in the presence of large quantities of ironby the double precipitation of UF4 followed by titration with ceric sul-219E. Bishop and V. J. Jennings, Talanta, 1961, 8, 22.2 2 0 E . Bishop and V. J. Jennings, Talanta, 1961, 8, 34.221E. Bishop and V. J. Jennings, Talanta, 1961, 8, 697.2 2 z B . Paschkes and B. Bernas, Analyt. Chim. Acta, 1961, 24, 5 .2z3 C. Nedorost and J. Brzobohatttjr, Chem. prumsyl, 1961, 11, 79.224 E. Schulek, J. Trompler, A. Endroi-Havas, and I. Remport, Analyt. Chim. Acta,225M.Eusef and M. H. Khundkar, Analyt. Chim. Acta, 1961, 24, 419.Z Z S Y . K. Gupta, 2. analyt. Chem., 1961, 180, 260.227 L. Szekeres, Ann. Chim., R m a , 1961, 51, 200.zzsH. Stockmann, J. Org. C h m . , 1961, 26, 2025.J. Laszlovsky, Pharm. Zentralhalle, 1961, 100, 77,23oY. K. Gupta, Analyt. Chim. Acta, 1961, 24, 415.Acid-base titrations.HaZogen titrations.Other redox titrations.1961, 24, 11CARTWRIGHT, WESTWOOD, AND WILSON 415phate.231 A cerimetric method has been applied to the determination ofmanganese in pyrolusite.232 The material is digested in oxalic-sulphuricacid mixture, filtered to remove silica, and titrated with use of ferroin asindicator.A titrimetric method for the assay of thiols has beendescribed233 in which the sample is dissolved in pyridine, aqueous silvernitrate solution is added, and the mixture is stored for 5 minutes.Wateris then added and the liquid is titrated with sodium hydroxide solution,phenolphthalein being the indicator.A review has been published of some of themost important indicators used in complexometric titrations and thedefinition of an ideal indicator has been discussed.234 The problem ofincreasing selectivity has been reviewed 235 and a method has been des-cribed for selecting the most suitable complexing agent for a particularmetal. 236PKbil and his co-workers have continued their work on basic problemsin complexometry with studies of the determination of thallium,237 themutual masking of iron and the masking of tervalent chrom-the determination of copper and iron,240 and the use of thioglycollicacid as a masking agent.241 Cheng 242 has studied the theoretical aspectsof masking and demasking reactions and has proposed a new term, theselectivity ratio, as an index to predict the possibility of unknown maskingreactions.Many examples of the more particular use of masking agents have beenpublished. In weakly acid solutions cyst eine forms colourless complexeswith certain cations, permitting the determination with EDTA of zinc, lead,nickel, aluminium, and iron in the presence of larger amounts of mercuryor Calcium and magnesium may be determined in the presenceof large amounts of manganese by masking the manganese with cyanide;24*and in the analysis of ferrites, magnesium, lead, and nickel may be sepa-rated by stepwise titration with EDTA using suitable masking agents.245I n the chelatometric determination of calcium it has been found thatsome improvement in the indicating properties of fluorescein may be attainedby mixing it with one quarter of its weight of phenolphthalein complexan.246Calcium and magnesium may be determined in ferromanganese slags after231 T.J. Blalock, U.S. Atomic Energy Comm., Rep. BM-RI-5687, 1959.232 M. R. Verma, S. K. Mathur, P. Dayal, and S. Adwani, 2. analyt. Chetn., 1961,233 B. Saville, Analyst, 1961, 86, 29.234 Z. Lada, Chem. Analit., 1961, 6, 135.235 T. S. West, Analyt. Chint. Acta, 1961, 25, 301.236 E. Wiinninen, Talanta, 1961, 8, 355.237 R. P?ibil, V. Veseljr, and K. Kratochvil, Tulanta, 1961, 8, 52.238 R.Pfibil and V. Veseljr, Talanta, 1961, 8, 270.239 R. Psibil and V. Veseljr, Talantu, 1961, 8, 565.240 R. P?ibil and V. Vesely, TaZanta, 1961, 8, 743.241R. P?ibil and V. Veself, Talanta, 1961, 8, 880.242 K. L. Cheng, Analyt. Chem., 1961, 33, 783.243 W. Berndt and J. $Bra, Tulanta, 1561, 8, 653.244 P. Povondra and R. Pcibil, Coll. Czech. Chem. Comnt., 1961, 26, 311.245 R. Pfibil and V. Vesely, Chenzist-Analyst, 1961, 50, 7 3 .a4aV. Svoboda, V. Chromjr, J. Korbl, and L. Dorazil, Talanta, 1961, 8, 249.Miscellaneous.Chelatometric titrations.180, 181416 ANALYTICAL CHEMISTRYthe removal of manganese by precipitation with potassium chlorate in nitricacid solution, and masking of iron, aluminium, and titanium with tri-ethanolamine. 247 The limits of interference by iron, manganese, aluminium,and phosphate in the EDTA determination of calcium in the presence ofmagnesium by means of Cal-red indicator have been investigated.248The complexometric determination of aluminium has been studied.249In the recommended method aluminium is boiled with excess of EDTA andthe excess is titrated with a standard lead solution.Sodium fluoride is thenadded to liberate EDTA equivalent to the aluminium present, and theliberated EDTA is titrated with lead solution, methyl thymol blue being theindicator. Methods for the indirect titration of thallium with EDTA in thepresence of iron or bismuth have been given,250 and the direct determinationof thallium in monocrystals of alkali-metal halides by EDTA titration atpH 3.8 using Xylenol Orange indicator has been rep0rted.2~1Two indicators, Acid Chrome Dark Blue (C.I.Mordant Blue 7) and AcidChrome Blue K, have been used in the EDTA titration of lead.Z52 Thesensitivity of both indicators in alkaline tartrate solution is greater thanthat of Chromogen Black ET-100 (C.I. Mordant Black 11). Silicic acid oralkaline silicates may be precipitated with cobalt(n) and the excess cobalttitrated with EDTA by using a mixed indicator (Eriochrome Black T andTropaeolin 00) for the indirect determination of the silicicZirconium may be determined in sulphuric acid solution by direct titra-tion with EDTA solution and Xylenol Orange as indicator;254 no inter-ference is caused by aluminium, lanthanum, cerium, zinc, cadmium, man-ganese, magnesium, chloride, nitrate, or molybdate, or by iron, indium,scandium, thorium, yttrium, nickel, or cobalt in amounts not greater than10 mg.Interference is caused by bismuth, phosphate, fluoride, and oxalate.Thorium may be titrated with EDTA at pH 1.6-3-0 with Chrome Azurol S(C.I. Mordant Blue 29) as indicator,255 or in the pH range 2.0 to 2.7 usingg alloc y anine indicator (dime t hylamino h y drox yp henoxy az onecar box y li cA method has been described for the rapid determination of phosphorusin coal.257 After ashing, the phosphate is precipitated as magnesiumammonium phosphate and the phosphate content is determined indirectlyby titrating the magnesium with EDTA solution and Eriochrome Black Tas indicator.The existence of a 1 : 1 complex of vanadyl(v) with EDTA has beenestablished from conductometric measurements and has been made the basis247 A.G. C. Morris, Analyt. Chem., 1961, 33, 599.248 P. Moss, J . Sci. Food Agric., 1961, 12, 30.249 0. Budevski and L. Simova-Filippova, Com,pt. rend. Acad. Bulg. Sci., 1961,250A. I. Busev and V. G. Tiptsova, Zhur. analyt. Khim., 1961, 16, 275.Z51 M. Kratochvil and J. Blecha, Chemist-Analyst, 1961, 50, 11.25% T. B. Styunkel’ and Z. A. Mikhaleva, Trudy Ural’sk. Politekh. Inst., 1960, 169;253 J. Jenik, Chem. prumysl, 1961, 11, 188.254 A. E. Klygin and N. S. Kolyada, Zavodskaya Lab., 1961, 27, 23.255 S . P. Sangal and A. K. Dey, 2. analyt. Chem., 1961, 178, 415.Z56S. P. Sangal and A.K. Dey, J. Indian Chem. SOL, 1961, 38, 75.257 A. C. Bhattacharyya, B. P. Bhaduri, and N. G. Banerjee, Analyst, 1961, 86, 195.14, 179.ref. Zhur. Khim., 1961, Abstr. No. 5073CARTWRIGHT, WESTWOOD, AND WILSON 41 7of a volumetric method for the determination of ~anadium.~5* The com-plexometric titration of uranium(rv) with EDTA is possible at pH 1.0-1.8by using thoron as the indi~ator.2~9 A study of the effect of other elementshas shown that thorium, cerium(Iv), and iron(=) interfere at a ratio of10 to 1, and that cobalt, copper, bismuth, mercury(n), vanadium, andfluoride hinder the titration.In the complexometric determination of iron it has been found thatN-benzoylphenylhydroxylamine (0.5% in acetone), phenylhydroxamic acid(3% aqueous), and sulphophenylhydroxamic acid (3% aqueous) all formred-violet complexes with iron(m) at pH 1-14, and can be used as indi-cators in EDTA titrations.260An unusual application of EDTA has been described by Beck,261 whohas reported that EDTA is oxidised in sulphuric acid or perchloric acidmedium by potassium permanganate but that no oxidation occurs whenEDTA is complexed with a metal ion.This fact has been applied to theindirect determination of bismuth and iron by adding an excess of EDTAto the solution of metal and back titrating the excess of complexing agentwith potassium permanganate solution.Chelatometric methods have been applied to the analysis of organo-metallic compounds.262 Thus aluminium alkyls may be decomposed withhydrochloric acid, the resulting aluminium chloride complexed with excessof EDTA, and the excess titrated with copper sulphate solution, withCatechol Violet as indicator.Non-aqueous titrations and functional-group determination.Develop-ments of indicators for non-aqueous acid-base titrations in the period 1959-1961 have been reviewed.263 The use of certain redox indicators in non-aqueous cerimetry has been s t ~ d i e d . ~ 6 ~ Some indicators used in aqueoussolution have been found satisfactory for the titration of quinol in glacialacetic acid. Sharp changes have been obtained with ferroin, diphenylamine,Methyl Red, and Janus Green, but the last two did not give reversiblechanges. Phenosafranine and Neutral Red were unsatisfactory. ‘Trifiuoromethanesulphonic acid has been used as a titrant in glacialacetic acid solutions and its performance has been compared with that ofperchloric a~id.~65 The only advantage offered is the freedom from pre-cipitate formation, and it is doubtful whether this alone is sufficient to justifythe use of the reagent in view of its high cost.Dimethylformamide may be purified for use in non-aqueous titrationsby treatment with Dowex 1-XI0 (OH- form) in a stoppered flask for severalhours.266268 G. Kakabadse and H. J. Wilson, Analyst, 1961, 86, 402.s6aP. N. Palei and Li-Yuan’ Hsu, Zhur. analit. Khim., 1961, 16, 51.a601. P. Alimarin and Tsz6 Yun’-Syan, Vestn. Moskow Univ., Ser. Khim., 1961,261 M. T. Beck, Chemist-Analyst, 1961, 50, 14.262 C. Hennart, Chim. Anal., 1961, 43, 283.263 W.C. Purdy and J. T. Stock, Chemist-Analyst, 1961, 50, 88.264G. P. Rao and A. R. Vasudevs Murthy, 2. analyt. Chem., 1961, 180, 169.2s5E. S. Lane, Talanta, 1961, 8, 849.266 R. E. Moskalyk, L. G. Chatten, and M. Pernarowski, J. Phurm. Sci., 1961, 50,No. 1, 59.179.418 ANALYTICAL CHEMISTRYMixtures of sulphuric acid and sulphonic acid may be determined bydifferential titration in acetone medium,267 using it solution of tetraethyl-ammonium hydroxide in benzene and methanol as the titrant, and a visualindicator consisting of a mixture of Neutral Red and thymolphthalein.Sulphate has been determined indirectly in the presence of interfering ionsby precipitation with excess of barium acetate and back titration of theexcess with perchloric acid in glacial acetic acid by a potentiometricmethod. 268Alkoxyl groups have been determined by absorption in pyridine anddirect titration with tetrabutylammonium hydroxide.269Primary and secondary amines have been determined with perchloricacid in acetic and the same reagent has been used for the titrationof organic bases and alkali-metal salts of organic acids.271 Basic compoundscontaining mercapto- or sulphide groups can be titrated with perchloric acidin acetic acid in the presence of mercuric acetate.272The rapid determination of organic hydroxyl groups has been des-cribed.273 The method is described for primary and secondary alcohols butmay also be applied to the determination of polyols, sugars, phenols, primaryand secondary amines, and some oximes.Sodium citrate and sodium potassium tartrate may be assayed by cationexchange in aqueous solution followed by titration in non-aqueous solu-tion.274 Kojic acid has been assayed by a non-aqueous titration using potas-sium methoxide in benzene-methanol as the titrant with Azo Violet indi-cator, and the use of kojic acid in the gravimetric determination of zinc hasbeen described.275Tetracyanoethylene has been used to determine aliphatic, alicyclic, andaromatic 1,3-dienes.276 The diene is allowed to react with an excess of thereagent in dichloromethane and the excess is titrated with cyclopentadienein ethanol.7.Instrumental end-point determinationsConductometric, amperometric, coulometric, potentiometric, and high-frequency methods in titrimetry are dealt with in this section.By far themost popular of these is still the potentiometric method, which with itsrelatively simple apparatus has accounted for more applications than allother end-point methods combined. Comparatively little development hasoccurred in conductometric or high-frequency methods owing to their lackof specificity. Coulometric methods have been increasingly used and thedevelopment of commercial potentiostats in this country will probablyZ67E. A. Gribova, Zavodskaya Lab., 1961, 27, 154.268 G. Goldstein, 0. Menis, and D. L. Manning, Analyt. Chem., 1961, 33, 266.269R. H. Cundiff and P. C. Markunas, Analyt. Chem., 1961, 33, 1028.2 7 O M . Rink and R. Lux, Arch. Pharm., 1961, 294; Mitt.deut. pharrn. Ges., 1961,271 M. Rink and R. Lux, Apoth.-Ztg., 1961, 101, 911.272 I. Bayer and E. Posgay, P h a m . Zentralhlle, 1961, 100, 65.273 W. T. Robinson, jun., R. H. Cundiff, and P. C. Markunas, Analyt. Ghern., 1961,27aM. L. Richardson, Analyt. Chim. Acta, 1961, 24, 46.276 C. Lents and W. Wagner, Chemist-Analyst, 1961, 50, 43.27aM. Ozolins and G. H. Schenk, Analyt. Chem., 1961, 33, 1035.31, 117.33, 1030CARTWRIGHT, WESTWOOD, AND WILSON 419result in an increased flow of applications a t controlled potential. Auto-matic titrimeters are being increasingly used and lend themselves to routinework. Thus the automatic titrator described by Haslam, Hamilton, andSquirrell 277 for elementa.1 analyses, where the whole process is done byautomatic control, gives an indication of things to come.In view of its increasing use a small sub-section has been devoted tochronopotentiometry.Although in a sense it is a coulometric method atconstant current, it utilises a rapid change of potential to signify the end ofthe process, the titrant being generated electrolytically. The transitiontime is the important measurement and a potential-time graph-the chrono-potentiogram-is obtained, First investigated by Delahay and Mam-antov 278 and based on an earlier sugge~tion,2'~ development of the methodhas been largely confined to the United States of America. A lack of readilyavailable constant- current devices has probably deterred analysts in thiscountry from testing the capabilities of this technique.A special mention should be made of the new technique put forward byBishop, 280 differential electrolytic potentiometry.The method consistsessentially of passing a minute but heavily stabilised current across a pairof stationary electrodes immersed in the titration solution and measuringthe potential developed across them. The electrodes behave independentlyand, when compared with an indicator electrode, one leads and the otherlags behind the indicator potential. If one species is not reversibly electro-lysed its potential remains more or less steady but the other shows a sig-nificant change in potential. The end-point is indicated, under appropriateconditions, by a very sharp peak in the potential-titre curve. Mention ismade of its application to very dilute solutions.Conductometric.-No significant developments have occurred in thistechnique over the last few years, and the number of papers is decreasing.This is inevitable in view of its lack of specificity and the superiority of othermethods particularly for determining increasingly small amounts.Anautomatic conductometric titrator has been described in which the con-ductance is recorded as a function of the titrant added, and is claimed togive a linear response up to 2.6 x lo4 ,umhos.281 A four-electrode assemblyinvolving a differential system has been applied to the determination ofcarbon dioxide and ammonia in scrubbing water for coke-oven gas.282Several flow systems involving conductometric measurements have beenused for elemental analyses.Thus the absorption cells devised by Green-field 283 and Stuck 284 for the micro-determination of carbon in organiccompounds after combustion utilise changes in conductance of alkali solu-tions. An absorption device is similarly used to determine carbon dioxidein air,285 and an indirect method for the continuous determination of2 7 7 J. Haslam, J. B. Hamilton, and D. C. M. Squirrell, Analyst, 1960, 85, 556.278P. Delahay and G. Mamantov, Analyt. Chem., 1955, 27, 478.279L. Gierst and A. Juliard, J. Phys. Chem., 1953, 57, 701.280 E. Bishop, Mikrochim. Acta, 1956, 619.281 D. W. Colvin and R. C. Propst, Analyt. Chem., 1960, 32, 1858.282E. Barendrecht and N. G. Janssen, Analyt. Chem., 1961, 33, 199.283 S. Greenfield, Analyst, 1960, 85, 486.284W.Stuck, Mikrochim. Acta, 1960, 421.285 I. Holm-Jensen, Analyt. Chinz. Acta, 1960, 23, 13420 ANALYTICAL CHEMISTRYacetaldehyde in aqueous liquid streams uses the sulphurous acid liberatedduring the SchB’s test.286Fifteen metal acetates have been successfully titrated with trichloro-acetic acid in aqueous solution,287 though some, mostly those of bivalentmetals, require the presence of 50% ethanol for reasonable end-points. Alarge number of weak bases, with ionisation constants between 10-8 and10-l2, have also been titrated with a similar titrant in 50% ethano1.288Formation of a 1 : 1 complex between vanadium(v) and EDTA has beendemonstrated 258 provided that the pH is >1.8 and [H+]/[Vv] is >5.Thorium, on the other hand, shows two inflections in the titration curvecorresponding to Th : EDTA = 1 : 1 and 1 : 2 respecti~ely.~8~ A criticalstudy has been made of the formula of ammonium phospho-l2-molybdateunder a variety of conditions of acidity, temperature, and concentrations ofreactants.290 The precipitate after solution in alkali is titrated with acidto reprecipitation.Micro-determination of sulphur in organic compoundsby the oxygen flask method has been elegantly carried out by titration wit,hbarium acetate. By prior neutralisation of the acids formed, only thesulphate is titrated and chloride does not interfere. Phosphate, if present,can be similarly eliminated by precipitation with silver nitrate.291Titrations have also been carried out in non-aqueous solutions.A num-ber of metal oxinates have been successfully determined in ethylenediaminesolutions with potassium methoxide in the same solvent,292 although a fewmetals, such as iron, thallium, and lanthanum, gave useless end-points.Sulphonates and phenoxates of calcium and barium, used as detergents inlubricating oils, have been determined directly in benzene-ethanol (1 : 1)mixtures by titration with a strong acid.293Czesium chloride has been titrated with antimony trichloride in a glacialacetic acid medium. 294Amperometric.-This continues to be a popular technique and has beenreviewed by Laitinen.295 A theoretical study has been made by Smit, whohas considered the cases of one- or two-indicator electrodes and has derivedrelationships between the current and concentration for reversible and irre-versible processes.296 Most of the work has been carried out with the con-ventional dropping mercury or rotated platinum electrodes but there hasbeen some tendency to use other indicating systems.Kolthoff et al. haveused the rotated aluminium electrode successfully for fluoride ion downto 10-5~,297 and rotated silver electrodes have been similarly used to deter-2 8 6 1 . A. Capuano, Analyt. Chem., 1960, 32, 1025.2 8 7 F. Gaslini and L. Z. Nahum, Analyt. Chim. Acta, 1961, 24, 79.2 8 8 F . Gaslini and L. Z. Nahum, Analyt. Chem., 1960, 32, 1027.289 V. T. Athavale, S. C. Saraiya, and A. K. Sundaram, Analyt. Chim. Acta, 1960,29’3P. Cannon, Talanta, 1960, 3, 219.291 J. P. Dixon, Analyst, 1961, 86, $97.2e2E.E. Underwood and A. L. Underwood, Talanta, 1960, 3, 249.293 J. Larbre and J. Briant, Rev. Inst. franc. PBroZe, 1960, 15 (7-8), 1170.se4 J. HaviP, Coll. Czech. Chem. Comm., 1960, 25, 695.296H. A. Laitinen, Analyt. Chem., 1960, 32, 180R.298 W. M. Smit, Chem. Weekblad, 1960, 56, 25.2871. M. Kolthoff and C. J. Sambucetti, Analyt. Chim. Acta, 1960, 22, 253; I . M.23, 200.Kolthoff, E. J. Meehan, and C. J. Sambucetti, ibid., p. 351CARTWRIGHT, WESTWOOD, AND WILSON 421mine cyanide ion down to a level of 10-8 g. in 7 ml. in the presence of athousand-fold excess of other ions.298Combinations of amperometry with other techniques have appeared.By using a square-wave generator, mixtures of ferrous and ferric ions werefirst complexed with EDTA and the ferrous complex was titrated with ferro-cyanide. The slopes of the current-voltage polarisation curves were usedfor end-point detection.299 By means of a combined dead-stop ampero-metric method, thallium ions were titrated in hydrochloric acid solution withpotassium iodate or with permanganate in the presence of bromide.300 Anautomatic coulometric-amperometric titrator giving direct readings in milli-equivalents of chloride per litre on a 0.1 ml.sample has been reported foranalysis of blood serum.3o1A number of metals have been determined by using EDTA as titrant.Zirconium has been titrated at a rotated tantalum electrode at f-1.2 v(S.C.E.) with little interference from other ions.302 However, in a recentreview by Milner and Edwards on the analytical chemistry of zirconium,303other amperometric methods are discussed and it is concluded that titri-metric methods involving indicators are probably preferable.Indium, asthe perchlorate, has been determined at pH 4-6 down to 5 x 1 0 - 5 ~ ~ con-~ e n t r a t i o n , ~ ~ ~ and thorium has been determined in monazite sand, afterremoval of the rare earths with oxalic acid, at +0.4 to +0*5 volt.305 Astudy has been made of EDTA as a titrant for metals at mercury and copperindicator electrodes. The results indicate that the electrode processes occurmuch faster in acid than alkaline solution.306 Arsenic and antimony canbe determined in one solution by using the rotated platinum ele~trode.~O'By titration with iodine at +0.2 v (S.C.E.) the two metals can be deter-mined, but in a similar solution after addition of 1.5 equivalents of the iodineneeded, the arsenic only is determined under the same conditions.Some novel titrants used in amperometry for the determination of metalsinclude tartrazine for zirconium 308 and the ammonium salts of benzene- andnaphthalene-selenonic acids, which are claimed to be very selective pre-cipitants for bismuth.309 Tetraphenylborate has been used for potassium,and is claimed to be more flexible and rapid than any other titrimetricmethod.310A recent adaptation ofthe titration with silver nitrate of chlorides, bromides, and iodides, singlyThe methods devised for anions are much fewer.298 J. A. McCloskey, Analyt.Chem., 1961, 33, 1842.299 L. C. Hall and D. A. Flanigan, Analyt. Chem., 1961, 33, 1495.300B. Sharma, Bull. Chem. SOC. Japan, 1960, 33, 277.301E. Cotlove and H. H. Nishi, CLin. Chem., 1961, 7, 285.302 V. A. Khadeev and F. F. Kvashina, Izv. VGssh. Ucheb. Zavedenii Khim. i Khim.303 G. W. C. Milner and J. W. Edwards, Analyst, 1960, 85, 86.304 J. Doleial and J. Z+ka, Coll. Czech. Chem. Comm., 1961, 26, 1464.305 P. N. Palei and N. I. Udal'tsova, Trudy Kom. analit. Khim., Akad. NaukS.S.S.R.,306 G. GuBrin, J. Desbarres, and B. Tremillon, J . EZectroanalyt. Chem., 1960, 1, 226.307V. A. Zakharov, 0. A. Songina, and N. A. Dragavtseva, Zavodskaya Lab.,308 G. Popa, D. Negoiu, and G. Baiulescu, Analyt. Chim. Acta, 1960, 22, 200.300V. S. Sotnikov and I.P. Alimarin, Talanta, 1961, 8, 588.310D. L. Smith, D. R. Jamieson, and P. J. Elving, Andyt. Chem., 1960, 32, 1253.Tekhnol., 1960, 3, 251.1960, 11, 299.1960, 26, 537422 ANALYTICAL CHEMISTRYand in mixtures, to the micro-determination of the combustion products oforganic compounds is claimed to be more rapid and accurate than existingmethods.311 After combustion, sulphur in petroleum products can be deter-mined as sulphide with mercuric chloride, down to 5 p.p.m. on a 0.2 g.sample. 312I n the organic field, the thiol group in cysteine, glutathione, and thio-glycollic acid has been determined a t the rotating platinum wire electrodeby argentimetric and mercurimetric titrations 313 and also by the rotateddropping mercury electrodeY3l4 ethylmercuric chloride being used as titrant.Penicillin, after conversion into penicillamine, has been determined, via itsSH group, with mercuric chl0ride.31~Aromatic aldehydes have been titrated with 2,4-dinitrophenyl-hydrazine, 316 and acetaldehyde with hydroxylamine hydrochloride, 317 withlittle interference from other compounds such as acetone. Glucose, fructose,and saccharose have been determined by ceric perchlorate at a platinum-wire indicator electrode at zero potential in a perchloric acid base elec-t r ~ l y t e .~ ~ ~Lead tannate, catecholate, and pyrogallolate have been successfullytitrated with dilute nitric acid, and the method has been applied to theanalysis of black wattle. 319Coulometric.-This technique is gaining ground although developmentsin Britain are slow, largely owing to lack of suitable industrial instruments.A comprehensive review by Lewis, 320 which clearly illustrates the possi-bilities of controlled-potential and constant-current methods, may provide astimulus for its further development. Other reviews 32l9 322 illustratedevelopments which have occurred abroad and discuss factors which mustbe considered for accurate results.Potentiostats are now available commercially, and the recent electronicdevice of Wadsworth 323 is fully transistorised with a wide range of availablecurrents ; although produced for electrodeposition analysis, it is eminentlysuitable for coulometric work.Similarly, the more elaborate multipurposeapparatus of Herringshaw and Halfhide is appli~able.~24 An instrumenthas been devised for phase analyses of large metallurgical samples,325 anda comprehensive titrator with integrator and automatic cut-off has beendevised for micro-quantities of metals.326 Circuits have also appeared for311s.Greenfield, R. A. D. Smith, and I. L. Jones, Mikrochim. Acta, 1961, 420.312 E. C. Schluter, E. P. Parry, and G. Matsuyama, Analyt. Chem., 1960, 32, 413.313 I. M. Kolthoff and J. Eisenstiidter, Analyt. Chim. Acta, 1961, 24, 83, 280.3l4 W. Stricks and S. K. Chakravarti, Analyt. Chem., 1961, 33, 194.3l5 J. Grafnetterovii, Cas. Le'E. Ces., 1960, 99, 182.3113 A. Berka, J. Doleial, J. Janata, and J. Z$ka, Anulyt. Chim. Acta, 1961, 25, 379.317 R. E. van Atta, W. W. Harrison, and D. E. Sellers, Anulyt.Chem., 1960,32, 1548.31'3E. MichaIski, K. Czarecki, and M. Ignczak, Tatanta, 1960, 5, 137.31s S. E. Drewes, Analyst, 1961, 86, 104.32oD. T. Lewis, Analyst, 1961, 86, 494.321 D. D. De Ford, Analyt. Chem., 1960, 32, 31R.32% E. Barendrecht, Chem. Weekblud, 1960, 50, 37.323N. J. Wadsworth, Analyst, 1960, 85, 673.324 J. F. Herringshaw and P. F. Halfhide, Analyst, 1960, 85, 69.325Yu. A. Klyachko, Yu. D. Labut'ev, and V. A. Mil'chev,326M. T. Kelley, H. C. Jones, and D. J. Fisher, Tulanta, 1960, 6, 185.'Zawodskuya Lab.,1960, 26, 217CARTWRIGHT, WESTWOOD, AND WILSON 423constant-current devices 3279 328 but little of significance has been publishedover the last two years on cell coulometers or current-integrating devices.The majority of papers have been devoted to inorganic applications withcontrolled potentials using instruments already reported.Several appli-cations to metals of importance in the nuclear-energy field have appeared.Uranium has been determined in the presence of thorium by an oxidationprocedure whereby U(IV) is oxidised to U(VI) a t +1.4 v (us. Ag/AgC1),329or reduced in a tripolyphosphate and sulphate base solution whereby molyb-denum and other metals do not interfere.33u A similar procedure has beenused to determine the osygen/uranium ratios in oxides of urani~m.~3lPlutonium in amounts down to 50 pg. has been determined,326 and a reduc-tion of PU(VI) with electrogenerated iron(@ has been reported. 332 Iron,in 2--6~-hydrochloric acid, has been determined by electrolytic oxidationafter a preliminary reduction to Fe(rr) with zinc or other metals.Themethod is claimed to give highly consistent results on standard samples,and manganese, chromium, and titanium do not interfere.333 Tin hasbeen determined as Sn(n) in a bromide medium at a mercury or tin analgamelectrode at -0-70 v (S.C.E.) 334 down to 20 mg. with an error of <0*3%;addition of tartrate prevents interference from antimony and copper. Ina methanolic tetraethylammonium bromide solution, europium and ytter-bium have been determined, at separate potentials, down to 0.5 , ~ e q u i v . ~ ~ ~By using a silver-plated platinum anode, chloride has been determined atvery low concentrations and the method is claimed to be more accurateand to require less sample than other methods.336 The system utilises anadditional silver electrode to act as sensor and the electrolysis is madeautomatic.Small amounts of iodides in the region of 30-100 pg. havealso been determined by an internal electrolysis method 337 with a platinumgauze anode and a lead dioxide-sulphuric acid paste cathode contained in anextraction thimble. Standard solutions of perchloric acid in methyl cyanidehave been prepared by coulometric oxidation of hydrogen in a 0.1M-SOdiUII1perchlorate solution, 338 and a technique using an ion-exchange membranehas been employed to generate a number of standard reagents which areotherwise tedious to prepare. 339 Novel applications include coulometricreduction of cuprous sulphide films on co~per,~*O suitable for up to 15pg./cm.2of sulphur, and to the investigation of the surfa.ce oxidation of platinumand g0ld.3~1327 T.Takahashi and H. Sakurai, Talanta, 1960, 5, 205.328 J. R. Glass and E. J. Moore, Analyt. Chem., 1960, 32, 1265.339 C. M. Boyd and 0. Menis, Analyt. Chern., 1961, 33, 1016.330 H. E. Zittel, L. B. Dunlap, and P. F. Thomason, AnaZyt. Chem., 1961, 33, 1491.331R. W. Stromatt and R. E. Connally, Analyt. Chem., 1961, 33, 345.338 W. D. Shults, Analyt. Chem., 1961, 33, 15.333P. S. Farrington, W. P. Schaefer, and J. M. Dunham, Analyt. Chem., 1961, 33,3JaA. J. Bard, Andyt. Ch;m. Acta, 1960, 22, 577.336E. N. Wise and E. J. Cokal, AnaZyt. Chem., 1960, 32, 1417.33sD. M. Coulson and L. A. Cavanagh, Analyt. Chem., 1960, 32, 1245.337 J. Kis and C.Schejtanow, Periodica Polytech., 1960, 4, 163.338 J. Vedel and B. TrArnillon, J . Electroanalyt. Chem., 1960, 1, 241.339R. B. Hanselman and L. B. Rogers, Analyt. Chem., 1960, 32, 1240.340 T. P. Hoar and C. D. Stockbridge, Electrochim. Acta, 1960, 3, 94.341H. A. Laitinen, Analyt. Chem., 1961, 33, 1458.1318424 ANALYTICAL CHEMISTRYApplications to organic systems are few. Ascorbic acid has, however,been determined at pH 6-03 and +1.090 v (S.C.E.), in the 15-100 mg.range, with an accuracy of h0.7 mg.342 Reaction of hydrazine and disub-stituted hydrazines by electrogenerated bromine has shown that six equiva-lents of bromine are consumed by the unsymmetrically disubstituted com-pounds, whereas hydrazine consumes four.The symmetrical compounds,however, do not behave stoicheiometrically. 343 Thymol has been deter-mined in Thymus vulgaris with electrogenerated bromine with an accuracyof &0-5% on a 0.5 mg. quantity.344With constant-current procedures, applications have been almost exclu-sively inorganic. Iron has been determined with electrogenerated brominein an acetic acid-acetate medium containing b r ~ m a t e , ~ ~ ~ but other media,e.g., sulphuric acid, were not suitable. From 2 to 13 mg. of platinum weredetermined to &06% by stannous ions produced electrolytically in asolution of high bromide c0ntent.3~6It is claimed that silver, nickel, and gold have been determined to a fewparts per thousand by constant-current generation of cyanide ions.347Permanganate produced coulometrically has been used to determine hydro-gen peroxide,348 and ferrocyanide and iodide i0ns.3~~ Fluoride has beentitrated as a base in acetic anhydride containing sodium perchlorate whereinperchloric acid is generated.350A novel method, called voltage-scanning c0ulometry,3~1 in which avoltage sweep is made between two electrodes, has been claimed to deter-mine traces of iron down to 0.025 pg.The peak current flowing is a measureof the amount of iron present.Potentiometric.-This continues to be the most popular method ofelectrometric end-point determination and accounts for more published workthan all other procedures combined. It frequently uses conventional elec-trodes with a pH meter or other simple polarising device.Recent reviewsdiscuss developments in methods s52 and application in non-aqueous solu-tions,353 and a comparison has been made with amperometric methods.354Constructional 355 and mathematical 356 methods for determining equiva-lence points have been discussed where these are not readily ascertainable.Theinstrument of Haslam, Hamilton, and Squirrel1 277 has been used for poten-34aK. S. V. Santhanam and V. R. Krishnan, Analyt. Chem., 1961, 33, 1493.343E, C. Olson, Analyt. Chem., 1960, 32, 1545.344 2. Kalinowska, Acta Polon. Pharm., 1960, 17, 153.345T. Takahashi and H. Sakurai, Talanta, 1960, 5, 205.346A. J. Bard, Analyt. Chem., .1960, 32, 623.347 F. C. Anson, K. H. Pool, and J. M. Wright, J. Electroanalyt. Chem., 1961, 2, 237.348P.S. Tutundiic and M. M. Paunovib, Analyt. Chim. Acta, 1960, 22, 291.349 P. S. Tutundiic, N. M. Paunovid, and M. M. Paunovid, Analyt. Chim. Acta, 1960,3 5 O W . B . Mather and F. C. Anson, Analyt. Chem., 1961, 33, 132.351 F. A. Scott, R. M. Peekema, and R. E. Connally, Analyt. Chem., 1961, 33,352 C. N. Reilley, Analyt. Chem., 1960, 32, 185R.353 J. A. Riddick, Analyt. Chem., 1960, 32, 172R.354 H. L. Kies, Chem. Weekblad, 1960, 56, 13.355 C. Liteanu and D. Cormos, Talanta, 1960, 7 , 25, 32.356 J. M. H. Fortuin, Analyt. Chim. Acta, 1961, 24, 175.A number of automatic recording titrators have been reported.22, 345.1024CARTWRIGHT, WESTWOOD, A N D WILSON 425tiometric work, and a modification of the Precision Dow recording titratorhas made it applicable to amperometric, conductometric, photometric, andthermometric uses.357 Other automatic instruments involve devices toslow down the rate of addition of titrant near the e n d - p ~ i n t .~ ~ ~ , 359 Graphiteelectrodes have been used for applications where others are unsuitable;considerably greater changes of potential occur at the end-point than withthe hydrogen electrode.360Most inorganic applications to metal ions involve oxidation titrations.A study has been made of the Lingane-Karplus reaction and it was shownthat the titration of manganese at pH 6-7 in pyrophosphate is not affectedby a large number of cations and anions.361 The reaction has also beenused to determine manganese in ferromanganese and other minerals. 362Cobalt, complexed with 1 ,lo-phenanthroline 363 or 2,2’-bi~yridyl,~~~ has beensuccessfully determined with ferric chloride.Formation of the complexconsiderably improves the potential change at the end-point. A titrationof cobalt with molybdicyanide 3e5 gave better results than with ferricyanide.The possibilities of ferricyanide titrations have been reviewed for a numberof metal ions.366Reduction processes include determination of thallium with chromium(I1)ions using conventional arrangement~,~~7 and the use of this titrant fordetermining small amounts of molybdate in the presence of excess of thio-cyanate has been Cerium(m) ions in alkaline solutions haveprovided an accurate method for determining milligram quantities of ferri-cyanide and permanganate with good end-points in 4~-potassium carbonatesolution. Concentrations down to 1.8 x mequiv./l.of ferricyanidegave reliable r e ~ u l t s . 3 ~ ~ Complexing agents have been used in several cases,as in the determination of mercury(I1) with EDTA 370 using a silver amalgamindicator electrode; 200 pg. to 100 mg. of mercury were reliably deter-mined. Calcium and magnesium have been determined in water 371 byautomatic titration with EDTA, the calcium first being titrated in sodiumhydroxide solution in the presence of standard mercuric nitrate solution,and then by adjustment of pH both are determined in the same sample.The formulze of complexes formed by zirconium with EDTA and six othercomplexing agents were investigated and the number of ligands involvedwas determined in each case.372 Formation of the complex KPeMo(CN),357 A.Anton and P. W. Mullen, Talanta, 1961, 8, 817.35sM. J. Kelley, D. J. Fisher, and E. B. Wagner, Analyt. Chem. 1960, 32, 61.359 J. R. Glass and E. J. Moore, Analyt. Chena., 1961, 33, 494.360 J. Beritik, Chem. Zvesti, 1960, 14, 372.361 W. G. Scribner, Analyt. Chem., 1960, 32, 966, 970; W. G. Scribner and R. A.362A. Jellinek and J. HoSala, Hutn. Listy, 1960, 15, 137.363 F. Vydra and R. Pfibil, Talaizta, 1960, 5, 44.364 F. Vydra and R. PFibil, Tulanta, 1961, 8, 824.365 B. Kratochvil and H. Diehl, Talanta, 1960, 3, 346.366 B. R. Sant and S. B. Sant, Z’alanta, 1960, 3, 261.367 R. Majumdar and M. L. Bhatnagar, AnaZyt. Chim. Acta, 1961, 25, 203.368 A. I. Busev and Gyn Li, Vestn.Moskou. Univ., Ser. Khim., 1960, 11, No. 2, 73.369N. H. Furman and A. J. Fenton, Analyt. Chem., 1960, 32, 745.3 7 0 H. Khalifa and M. G. Allam, Analyt. Chim. Acta, 1960, 22, 421.371 J. Haslam, D. C. &I. Squirrell, and I. G. Blackwell, Analyst, 1960, 85, 27.372 B. I. Intorre and A. E. Martell, J . Amer. Chem. SOC., 1960, 82, 358.Anduze, ibid., 1961, 33, 770426 ANALYTICAL CHEMISTRYhas been established by studies of the reaction between iron and molybdi-cyanide ions.373Several papers have been devoted to the determination of halides.Bromides in the range 87-193 pug. have been determined in the presence ofmercuric ions by using an amalgamated silver wire electrode and titrationwith silver nitrate in perchloric acid solution.374 Micro-amounts of iodidein a large excess of chloride were determined by a null-point potentiometricmethod which was claimed to be rapid when applied to iodised salt;3755-100 p.p.m.were determined with an average error of <0.3 p.p.m. byusing a silver-silver iodide electrode. Chlorides are readily determinedpotentiometrically after combustion of organic compounds by the oxygen-flask method.376 A good dead-stop method for the determination ofalkali sulphides involves the use of cadmium acetate. Only hydroxide andcyanide ions interfere in the titration.377 Extreme dilutions (10 - 7 ~ ) arealso claimed by a silver nitrate t i t r a t i ~ n . ~ ~ ~ In a similar investigation,small amounts of sulphide, hydrosulphide, and free hydrogen sulphidewere determined by appropriate adjustments of the pH.379 Borates inmixed fertilisers have been simply determined, after precipitation of thephosphate by bismuth, by a mannitol titration using an identical pH pro-cedure.380 Some inorganic ion8 have been titrated in non-aqueous solvents.Titrations of iodine, bromine, copper(=), iron(m), and antimony(v) havebeen carried out with chromium(=) and titanium(m) chlorides in NN-dimethylformamide.381 Sulphate ions in an acetic acid medium weredetermined by adding excess of barium acetate and back titrating theexcess with perchloric acid in acetic acid.268 The method was applied tothe total sulphate content of solutions used for dissolving reactor fuels.In the organic field, organic solvents are generally used.A comparisonof solvents for non-aqueous titrations of weak organic bases with perchloricacid has shown that acetic acid is preferable to formic or propionic acid inspite of their better levelling 382 Alkoxyl groups have beendetermined by conversion into the alkyl iodide, which was absorbed inpyridine and titrated with tetrabutylammonium hydroxide. 269 The sametitrant and solvent have been used for titrating the 3,5-dinitrobenzoatesof a number of primary and secondary alcohols.383 A number of car-boxylic acid chlorides have been titrated directly in tetrahydrofuran withcyclohexylamine, an ordinary glass-calomel assembly being ~ s e d . 3 ~ ~ Car-373 W. U. Malik and s. I. Ali, Talanta, 1961, 8, 737.374H. J. V. Tyrrell and B.A. Dowson, Analyst, 1960, 85, 528.s7sH. V. Malmstadt and J. D. Winefordner, A d y t . Chim. Acta, 1961, 24, 91.376 J. Haslam, J. B. Hamilton, and D. C. M. Squirrell, Analyst, 1960, 85, 856;J . Appl. Chem., 1960, 10, 97; D. G. Newman and C. Tomlinson, Mikrochim. Ada,1961, 73.377 S. A. Kiss, Talanta, 1961, 8, 726.378 M. W. Tamele, V. C. Irvine, and L. B. Ryland, AnaEyt. Chem., 1960, 32, 1002.37s K. P. Mishchenko, T. A. Tumanova, and I. E. Flis, Zhur. analyt. Khim., 1960,3soH. N. Wilson and G. U. M. Pellegrini, Analyst, 1961, 86, 517.381 J. F. Hinton and H. M. Tomlinson, Anulyt. Chem., 1961, 33, 1502.M. Gutterson and T. S. Ma, Mikrochim. Acta, 1960, 1.3B3 W. T. Robinson, R. H. CundX, A. J. Sensabaugh, and P. C. Markunas, Talanta,15, 211.1960, 3, 307.384L. J. Lohr, Analyt. Chem., 1960, 32, 1166C ART WRIGHT , WE S T W 0 0 D , 427boxylic acids do not interfere, but free hydrochloric acid does, and mustbe corrected for.Differential electrolytic potentiometry, developed by Bishop, has shownpromise of becoming a highly accurate method a t low concentrations. Aspecial study has been made of the oxidation of hydrazine by electrogeneratedbromine down to ~0-6M-so~utions. An accuracy of &0*1% at these levelsis claimed.385 Athorough examination of the variables such as electrode size and position,source, potential, etc., and their effects on the titration curve, has beenmade. An optimum ballast load resistance and controlled cathode currentdensity are required to avoid distortion of the curves.386This is a rapidly expanding technique which hasbeen almost exclusively developed in the United States of America.Rein-muth et al. have studied the theoretical and mathematical aspects of thecurrent-time curves 38 and the significance of the electrode processes.388Theoretical studies of transition times and diffusion at cylindrical electrodeshave been made with a view to checking their analytical pos~ibilities.~~~Errorsarising from oxide film on the platinum cathode were investigated andindirect methods for determining oxalic acid and iron(u1) were devel0ped.3~~Manganese in steels was determined by oxidation at a gold electrode in anacid periodate solution at +O.SO v (S.C.E.).391The reduction of perchlorate to chloride catalysed by molybdenum hasbeen studied and shown to be suitable for analytical purposes.A mechan-ism involving molybdenum-(v) and -(n) has been s~ggested.3~2Studies of oxide films on platinum electrodes have shown that films upto an equivalent of 80 p-coulombslcm. permit normal diffusion control ;reduction of the oxide occurs by a 4-electron pr0cess.3~~ A novel applica-tion involves liquid bismuth used as a coolant in reactor technology. Tracesof zinc are picked up as corrosion products and can be determined by makingthe molten bismuth the anode in a fused lithium chloride-potassium chlorideelectrolyte. moles/ml. can be determined 394High Frequency.-A recent review by Ladd and Lee 395 gives a clearaccount of the theory, the available apparatus, and applications to ionicreactions.Most of the rather small number of papers which have appearedhave been devoted to improvements in instruments or circuits. A newtitrimeter operating at 130 Mc./sec. has been shown to be able to determine385 E. Bishop, Milcrochim. Acta, 1960, 803.887W. H. Reinmuth, Analyt. Chem., 1960, 32, 1509, 1514; 1961, 33, 322; 1961,AN D WIL SO NVolumes down t o 50 pl. are dealt with in a special cell.Chronopotentiometric.Cerium(1v) has been studied over the range 2-20 millimoles/litre.Zinc down to 1.19 xto &4y&E. Bishop, Analyst, 1960, 85, 422.33. 485.~ 3 8 8 A . C. Testa and W. H. Reinmuth, Analyt. Chem., 1961, 33, 1320, 1324; 1960,32. 1518.389D. G. Peters and J. J. Lingane, J . Electroanalyt. Chem., 1961, 2, 249.390D.G. Davis, Analyt. Chem., 1961, 33, 1839.selD. G. Davis and J. Ganchoff, J. Electroanalyt. Chem., 1960, 1, 248.39zG. A. Rechnitz and H. A. Laitinen, Analyt. Chem., 1961, 33, 1473.393 J. J. Lingane, J . Electroanalyt. Chem., 1961, 2, 296.304 J. D. van Norman, Analyt. Chem., 1961, 53, 946.995M. F. C . Ladd and W. H. Lee, Talanta, 1960, 4, 274428 ANALYTICAL CHEMISTRY1 ,ug./ml. of hydrochloric acid and 20 ,ug./ml. of acetic acid by using sodiumand ammonium hydroxides as titrants.396 The feasibility of using a modu-lated off-balance R.F. signal from the detector side of a R.F. impedancebridge was tested and found to give very suitable titration curves at 30Mc./sec. for 0-Oh-hydrochloric and 0-1N-acetic a ~ i d s . 3 ~ ~ A simple H.F.titrator, suitable for a number of student applications and based on a hetero-dyne-beat principle a t 120 Mc./sec., has been described.398 A simpletransmission line operating at 190 Mc./sec.involves changes in grid currentwhich are transformed to a voltage applied to a recorder, and are used indetermining free acid in uranium solutions by alkali titration, and thoriumby oxalic acid or EDTA titration, in mg. quantities.399 The H.F. methodhas been combined with paper chromatography as a zone locator,400 par-ticularly for lithium, sodium, and potassium where the change in impedanceof the cell has been used as a measure of these elements,401 and as a “ humid-ity gauge.” 402Chloride-ion concentrations down to 0.3 p.p.m. and sulphide to 1 p.p.m.have been recorded by H.F.titrimetry using 0.001N-silver nitrate andoperating at 11 M~./sec.~O~Oxalic, malonic, succinic, tartaric, and citric acids have been determinedin mg. quantities by ammonia in the 130 Mc./sec. region by means of theapparatus quoted above. 396 Tervalent arsenic and antimony have similarlybeen determined with iodine.*04A study has been made of various solvents suitable for H.F. titrimetryof weak acids, and acetonitrile was considered to give the best response withtetrabutylammonium hydroxide as titrant. 405 The comparative behaviourof the alkali-metal methoxides in benzene-methanol solution by titrationwith aliphatic and aromatic weak acids in dimethylformamide showed thatthe rubidium and cmium compounds acted as strong bases, but lithiummethoxide was very weak.The ammonium ion acted as a strong acid.4068. Determination of elements in organic compoundsThe development and applications of the microchemical balance havebeen reviewed.407 Some corrections are advocated for achieving the highestaccuracy in microchemical weighings 408 and methods for deriving themare given. ,Two reviews have been published of quantitative organic microanalysis.3*6E, Pungor and L. Balazs, Mikrochim. Acta, 1960, 118.397 J. E. Walker, J. L. Lambert, and L. D. Ellsworth, Analyt. Chem., 1960, 32, 9.398 J. K. Clinkscales and H. Frye, J . Chem. Educ., 1960, 37, 304.399D. L. Manning and 0. Menis, Talanta, 1960, 6, 30.400 G. G. Blake, Analyt. Chim. Acta, 1960, 22, 38.401 J.A. Broomhead and N. A. Gibson, Analyt. Chim. Acta, 1961, 24, 446.4ozG. G. Blake, Analyt. Chim. Acta, 1960, -23, 10.403 N. van Mews, J. Electroanalyt. Chem., 1961, 2, 17.404E. Pungor and L. Balazs, Mikrochim. Acta, 1960, 678.406 E. L. Grove and W. S. Jeffery, Talanta, 1960, 7, 56.406 S. F. Ting, W. S. Jeffery, and E. L. Grove, Talanta, 1960, 3, 240.‘07 G. Ingram, I n d . Chemist, 1961, 37, 343.40a W. Durselen, 2. Chem., 1961, 1, 119CARTWRIGHT, WESTWOOD, AND WILSON 429One 409 deals with weighing and preparing samples, determining carbon,hydrogen, oxygen, and nitrogen, the flask method for a number of elements,and the determination of many functional groups. The other is confinedto quantitative elemental meth0ds,~10 and deals with the importance of theflask-combustion method, with improvements in carbon and hydrogendetermination, and with problems involved in determining traces of elementsand in ultramicro-analysis. In a critical review of the oxygen-flask method,Macdonald 411 discusses procedures for the combustion, and for determininghalogens, sulphur, phosphorus, arsenic, boron, and some metals.Themethod has been modified 412 to deal with the determination of residuesof arsenic, chloride, bromide, manganese, and nickel in plant material, andprocedures have been described 413 for the rapid detection and semiquanti-tative estimation of a number of elements in plastic materials.A modification of furnace design is described 414 which combines rapidheating of the combustion tube with reliability.The process of decomposi-tion of organic compounds in a rapid flow of oxygen has been disc~ssed.~l~Ingram 416 has described an apparatus in whichthe sample is rapidly introduced into a closed heated tube containing oxygen ;when combustion is complete the gases are swept out and the determinationof carbon and hydrogen is completed in the usual way. Determination ofcarbon following flask combustion is described by Cheng and S m ~ l l i n . * ~ ~The sample is ignited electrically, the carbon dioxide is absorbed in alkalinebarium chloride solution, and the separated barium carbonate is dissolvedin standard acid, the excess of which is titrated.Thermally stable samples, enclosed in a platinum roll, have been heatedby an induction furnace,418 enabling a temperature of 1300" to be attainedwithout softening the silica combustion tube.A number of catalysts used in rapid combustion methods have beencompared, and Co304 has been selected as the best.The kinetics andmechanism of the catalysed combustion were examined, and conditions forthe shortest combustion and sweeping times are given.419 The use of Co,O,as catalyst is also reported in a method 420 whereby the sample is burnedin oxygen to give carbon dioxide, in nitrogen to give water which is reducedto hydrogen, or in carbon dioxide to give nitrogen, the gas in each casebeing measured by thermal conductivity. The same catalyst is used ina semimicro-method for carbon and hydrogen. 421 The " decomposed silverpermanganate " catalyst is recommended for organomercury compounds,Carbon and hydrogen.J .40B W.Schoniger and H. Lieb, Purnaco, E d . Sci., 1961, 2, 81.410P. Gouverneur, Chem. Weekblad, 1961, 57, 313.411 A. M. G. Macdonald, Analyst, 1961, 86, 3.412 W. H. Gufenmann, L. E. Saint John, D. L. Barry, E. D. Jones, and D. J. Lisk,Agric. Food Chem., 1961, 9, 50.413 J. Haslam, 5. B. Hamilton, and D. C. M. Squirrell, Analyst, 1961, 86, 239.414 J. A. Kuck, J. W. Berry, and L. H. Barnum, Microchem. J., 1961, 5, 193.415V. A. Klimova and T. A. Antipova, Zhur. analit. Khim., 1961, 16, 343.416 G. Ingram, Analyst, 1961, 86, 411.417 F. W. Cheng and C. F. Smullin, Microchem. J., 1961, 5, 43.41sD. E. Butterworth, Analyst, 1961, 86, 357.41eM. VeEeFa, D. Snobl, and L.Synek, Mikrochim. Acta, 1961, 370.llaoM. VeEeFa, Talanta, 1961, 8, 446.421C. Meyer and G. Vetter, Chem. Tech. (Berlin), 1961, 13, 104430 ANALYTICAL CHEMISTRYand a method is given 422 for determining mercury, if halogens are absent,as well as carbon and hydrogen.Although the method was not tested on fluorocarbons, difficulties dueto fluorine in other compounds were overcome by using magnesium oxidein a silver gauze roll, the combination proving effective in removing all thehalogens and The method of halogen and sulphur determinationhas been modified 424 to permit simultaneous determination of carbon andhydrogen. The preparation is described 425 of silver in granular form, whichhas the same capacity for removing halogens and sulphur as silver wool,but is more convenient to use.Carbon- 14 can be determined after oxygen-flask combustion by propor-tional counting 426 or, as well as tritium, by liquid-scintillation techniq~es.~27Nitrogen. A convenient apparatus is described 428 for generating carbondioxide for Dumas combustion, using potassium hydrogen carbonate andsulphuric acid.An investigation 429 of the Dumas combustion by gaschromatography has resulted in recommendations for both apparatus andmethod. The combination of combustion and gas chromatography hasbeen used 430 to determine nitrogen, in one method in terms of carbon : nitro-gen ratio, and in another, using carbon dioxide as the carrier gas, by thenitrogen peak alone; neither method requires a weighed sample, and goodaccuracy is claimed for both.Methods for determining nitrogen in compounds containing fluorine havebeen reviewed, and a modified Dumas train has been devised 431 in whichhigher temperatures are used and a simple generator permits intermit tentflow of oxygen when required.Comparison has been made of Dumas, Kjeldahl, and other methods ofdetermining nitrogen in solid fuels, 432 the recommended method beingreductive digestion with metallic lithium, followed by decomposition of thenitride with phosphoric acid and distillation of ammonia from the alkalinesolution.The determination of nitrogen, following combustion, by measure-ment of thermal conductivity has already been mentioned. 420The process of digestion in the Kjeldahl method has been investigated byBaker,*33 and clear evidence is advanced that mercuric oxide, of 21 singleand mixed catalysts examined, is the most effective; a higher than usualconcentration of potassium sulphate is also recommended. A bent test-tube has proved more reliable 434 than the conventional Kjeldahl flask inthe digestion of blood plasma and plant material.422A.I. Lebedeva and E. F. Fedorova, Zhur. analit. Khim., 1961, 16, 87.423G. Ingram, Analyst, 1961, 86, 539.424 Toshihiro Onoe, Chizuru Furukawa, and Hiro Otsuka, Ann. Report Takamine425 Tetsuo Mitsui, Osamu Yamamoto, and Keikichi Yoshikawa, Mikrochim. Acta,426H. Kienitz and 0. Riedel, 2. unalyt. Chem., 1961, 179, 93.4 2 7 R . G. Kelly, E. A. Pests, and D. A. Buyske, Analyt. Bwchem., 1961, 2, 267.428 M.Hocheneggar, Mikrochim. Acta, 1961, 431.429 M. &mek and K. TesaFik, Coll. Czech. Chem. Comm., 1961, 26, 1337.43oR. H. Reitsema and N. L. Allphin, AnaEyt. Chem., 1961, 33, 355.43lG. Kakabadse and B. Manohin, Analyst, 1961, 86, 512.432 W. Radmacher and A. Hoverath, L;rliickazcf, 1960, 96, 1146.433 P. R. W. Baker, Talunta, 1961, 8, 57.434V. Fojtova and J. Pud, Chem. Listy, 1961, 56, 201.Lab., 1959, 11, 100,1961, 521CARTWRIGHT, WESTWOOD, AND WILSON 43 1The direct determination of oxygen by the Unterzauchermethod has been applied to organic oxygen in coals,435 and a new method 436employing platinised asbestos and platinum-rhodium gauze a t 700" hasbeen applied to compounds containing carbon, hydrogen, and oxygen ; thecarbon dioxide and water produced by pyrolysis are absorbed in one pairof absorption tubes, and the carbon monoxide and hydrogen are oxidisedby heated copper oxide and absorbed in another pair of tubes, the first ofwhich is weighed.Accuracy of better than &-0-2y0 was obtained for mostsamples.Halogens. Some aspects of halogen determination have already beenm e n t i ~ n e d . ~ l ~ - ~ l ~ ? 424 Although most workers now use the oxygen-flaskmethod of decomposition for halogens, with a variety of finishes, combustionin a stream of oxygen has received attention. Fildes and Macdonald 437describe titrimetric methods for determining individual halogens in presenceand absence of nitrogen and sulphur, following a specified rapid combustionprocedure, and Belcher and Fildes 438 deal with simultaneous determinationof chlorine, bromine, and iodine in presence of nitrogen and sulphur, witha study of optimum conditions for absorption.Pella 439 makes provisionfor dealing with explosive and volatile compounds, and gives methods withtitrimetric finishes for determining chlorine, bromine, and sulphur separately,and chlorine and sulphur simultaneously. A modified combustion overplatinum contacts, with the products drawn into an evacuated flask con-taining hydrogen peroxide solution and titrated amperometrically, hasbeen used 440 in a general method of determining chlorine, bromine, andiodine. The determination of iodine after combustion in the oxy-hydrogenfla,me is des~ribed.~~IIn the oxygen-flask combustion of compounds with high halogen contentit is recommended 442 that the filter paper be saturated with dilute potassiumnitrate solution.Following flask combustion, the titrimetric determinationusing mercuric nitrate with diphenylcarbazone as indicator is generallyfavoured,442, 4439 444 but Hennart 445 proposes a method involving additionof excess of silver nitrate, filtering off the resulting precipitate, treating thefiltrate with excess of K,[Ni(CN),], and titrating with EDTA the nickeldisplaced by silver from the cyanide complex.Olson andShaw 446 use the spectrophotometric finish with thorium chloranilate.Martin et advocate the thorium nitrate titration with Alizarin S asindicator for major quantities, and the colorimetric zirconium-alizarinOxygen.Various methods are still favoured for determining fluorine.435 A.Crawford, M. Glover, and J. H. Wood, Mikrochim. Acta, 1961, 46.436V. S. Pansare and V. N. Mulay, Mikrochim. Acta, 1961, 606.437 J. E. Fildes and A. M. G. Macdonald, AnuZyt. Chim. A&, 1961, 24, 121.438R. Belcher and J. E. Fildes, Artalyt. Chim. A d a , 1961, 25, 34.43gE. Pella, Mikrochirn. Acta, 1961, 472.440 S. Greedeld, R. A. D. Smith, and I. L. Jones, Mikrochim. Acta, 1961, 420.441 F. Ehrenberger, Mikrochim. Acta, 1961, 590.lrpaI. A. Favorskaya and V. I. Lukina, Vestnilc Leningrad Univ., 1961, 2, 148.443 W. A. Cook, Microchem. J., 1961, 5, 67.444 D. C. White, Mikrochim. Acta, 1961, 449.445 C. Hennart, Mikrochim. Acta, 1961, 543.44eE. C. Olson and S .R. Shaw, Microchem. J . , 1961, 5, 101.447 F. Martin, A. Floret, and M. Dillier, Bull. SOC. chim. France, 1961, 460.432 ANALYTICAL CHEMISTRYmethod for traces. Johnson and Leonard 448 apply a spectrophotometricmeasurement to the blue complex formed by fluoride ions and the cerium(m)chelate of alizarin complexan, pointing out that the use of borosilicate glassflasks tends to give low results; the blue complex has been investigated inanother context. 449 Nuclear magnetic measurement 450 provides a specificand rapid method of determining fluorine in fluorocarbon liquids, but notwith the accuracy usually sought. Valach451 has critically examined anumber of methods of determining fluorine.Decomposition of organic compounds by the biphenyl-sodium dimethoxy-ethane complex, for determination of halogens, has been modified to dealwith volatile ~amples.~~2Sulphur. Flask combustion is now generally accepted as the methodof de~omposition.~l~s 453 A 2-litre flask is ~ s e d , ~ ~ 4 with turbidimetricmeasurement of barium sulphate, in determining traces of sulphur inpoly(methy1 methacrylate). Dixon 291 discusses a number of rapid micro-methods, using mainly a conductometric titration with barium ions.Thebarium nitrate titration has been used with Alizarin S 455 and with carboxy-arsenazo-indicators. 456Other elements. Methods have been given for determining phos-phoru~,411~ 457 arsenic, and boron, and metals 4119 412 following the flask' combustion. Boron, with mannitol added, has been titrated potentiometric-ally following Carius oxidation.458 A rapid method for determiningsilicon 459 is based on oxidation of the sample by chromic and sulphuricacids, fltration of the silica and solution of it in sodium hydroxide, followedby addition of ammonium fluoride to convert it into fluorosilicate in thepresence of an acid, and back-titration of the excess of acid with alkali.9.Spectroscopic analysisThis section is again divided into emission spectroscopy, including flamephotometry, fluorimetry, and X-ray methods ; and absorption spectroscopywhich embraces ultraviolet and visual absorption, turbidimetric, atomicabsorption, infrared absorption, and nuclear magnetic resonance methods.General.-In the Proceedings of the 8th Spectrochemical Conference 460papers are included dealing with modern electrical equipment for spectro-chemistry, the determination of several elements by spectrographic methods,and the applications of fluorimetric, X-ray fluorescent, and flame-photometricmethods.a4*C.A. Johnson and M. A. Leonard, Analyst, 1961, 86, 101.449 P. G. Jeffery and D. Williams, Analyst, 1961, 86, 590.a50H. Rubin and R. E. Swarbrick, Analyt. Chem., 1961, 33, 217.451R. Valach, Talanta, 1961, 8, 629.45aR. D. Chambers, W. K. R. Musgrave, and J. Savory, Analyst, 1961, 86, 356.453 C. Vickers and J. V. Willtinson, J . Pharm. Pharmacol., 1961, 13, 72.454 J. Haslam and D. C. M. Squirrell, J . Appl. Chem., 1961, 11, 244.455A. I. Lebedeva and I. V. Novozhilova, Zhur. analit. Khim., 1961, 16, 223.a5eK.F. Novikova, N. N. Basargin, and M. F. Ts9ganova, Zhur. analit. Khwn.,457A. M. Ryadnina, Zavodskaya Lab., 1961, 27, 405.458 D. G. Shaheen and R. S. Braman, Analyt. Chem., 1961, 33, 893.459A. P. Terent'ev, S. V. Syavtsillo, and B. M. Luskina, Zhur. analit. Khim., 1961,1961, 16, 348.16, 83. 480 S. Martino di Castrozza, Metallurg. Ital., 1961, 53, No. 5CARTWRIGHT, WESTWOOD, A N D WILSON 433In a critical review of colorimetric and spectrographic methods for theanalysis of gold, in which the limitations of many methods are discussed,Beamish 461 finds that no colorimetric or spectrographic method yet pub-lished gives the precision of the classical methods.Emission Spectroscopy.-Ignited arc sources have been compared withparticular reference to the determination of boron in steel and of tin andantimony in lead alloy.462 The theoretical and experimental aspects ofthe analysis of gases and vapours by emission spectroscopy have beendiscussed 463 and current literature on molecular emission spectroscopy hasbeen reviewed.Among the many applications of emission spectroscopy to the analysisof metals, the determination of beryllium metal and compounds has beendescribed 464 and a method has been given for the quantitative determina-tion of gallium in mi~ro-samples.~~~Methods for the analysis of non-metals include the determination ofboron in nuclear g r a ~ h i t e , 4 ~ ~ traces of boron in silicon tetrachloride, 467 andthe determination of halogens in solution. 468Further work on the determination of nitrogen in steels 469 has shownthat the Ar 8179 A band, which has been previously used, is a Rowlandghost of the strong Ar band a t 8115.3 A and that it is peculiar to theparticular grating used.is said t o beof more general use.Spectrographic methods continue to find use in the determination oftrace impurities following concentration. Thus copper, zinc, manganese,lead, tin, nickel, and iron in sodium and potassium salts may be determinedfollowing precipitation with 8-hydroxyquinoline and thionalide after theaddition of alumini~m.~70 Traces of cobalt, chromium, copper, man-ganese, molybdenum, nickel, titanium, vanadium, tungsten, zirconium,aluminium, and cadmium in steel can be determined after concentrationwith suitable organic reagents.471The experimental principles and the applications offlame photometry to the determination of various metals have been re-viewed.472 The factors influencing the accuracy of determinations by flamephotometry have been investigatedY4T3 and a study has been made of thefactors iduencing sample flow rate.474In the determination of lithium in silicate minerals it has been foundaslF.E. Beamish, Analyt. Chenl., 1961, 33, 1059.4saT. P. Schreiber and B. W. Joseph, Appl. Spectroscopy, 1961, 15, 8.463 W. D. McGrath, R. J. Magee, W. F. Pickering, and C. L. Wilson, Talanta, 1961,464M. A. Lund and D. L. G. Smith, A.E.R.E. Report-AM 73, 1961.4s5E. M. Murt and J. C . Bready, Appl. Spectroscopy, 1961, 15, 1.rs6F. Gianni and F. Potenza, Analyt.Chisn. Acta, 1961, 25, 90.467T. J. Veleker and E. J. Mehalchick, Analyt. Chem., 1961, 33, 767.468 J. Fijalkowski and A. Zelle, Chem. Analit., 1961, 6, 323.469Hitoshi Karnada and V. A. Fassel, Spectrochim. Acta, 1961, 17, 121.470R. L. Dehm, W. G. Dunn, and E. R. Loder, Analyt. Chem., 1961, 33, 607.471 F. Burriel-Marti, J. Ramirez-Muiioz, and M. del Carmen Asuncih, Inst. Hierro472 W. Leithe, Angew. Chern., 1961, 73, 488.473 S . Dobos and.F. Till, Magyar Kim. Folydirut, 1961, 67, 183.474 J. D. Winefordner and H. W. Latz, Analyt. Chem., 1961, 33, 1727.The line pair N 8216 A-Ar 8053Phme photometry.8, 892.Acero, 1961, 14, 518434 ANALYTICAL CHEMISTRYthat the most accurate results are obtained when interfering elements suchas iron, manganese, and aluminium are removed.475 Sodium and potassiumhave been determined in the presence of other metals,476 and methods havebeen given for overcoming some interferences ; calcium, strontium, andcerium may be suppressed by the addition of aluminium nitrate, whilemanganese, nickel, cobalt, chromium(m), and iron may be retained as theirEDTA complexes on ion-exchange columns.A detailed study has been made of the flame-photometric determinationof silver, and the behaviour of metals and anions associated with silver hasbeen examined.477 Indium and thallium have been determined in anacetylene-air flame, and gallium, indium, and thallium in an oxy-hydrogenflame.478FZzwrimetry. The importance of compiling data of fluorescence sensi-tivities in such a way that the values are independent of the instrumentsused to measure them has been discussed by Parker.479 The conditionsunder which fluorescence is obtained and the presentation of measuredfluorescence spectra have been reviewed.48 OThe use of quinine sulphate as a fluorescence standard has been studied,and measurements have been made of the intensity of its fluorescence inaqueous and acetic acid solutions with additions of sulphuric and perchloricacids.481 I n aqueous solution constant fluorescence intensity can only beobtained at a pH not greater than 2. The intensity is not affected byphosphate buffers but is slightly quenched by phthalate buffers. Whenglacial acetic acid is used as the solvent the fluorescence intensity is greaterand remains constant over the range 0.Ol-l.ON-perchloric acid.Theeffect of chloride ion on the fluorescence of quinine and its dependence onacid concentration 482 and salt concentration 483 have also been studied.The design and circuit details have been given of an improved fluorimeterfor uranium analysis. 484 A simple fluorimeter which has been constructedin the laboratory has been described 485 and an account has been given ofits use in an investigation of the benzoin method for the determination ofboron.In inorganic analysis beryllium has been determined in boron 486 by afluorimetric method using 3-hydroxy-2-naphthoic acid a t pH greater than2.5. Zinc can be effectively determined with Rhodamine B (C.I. BasicViolet 10) by measuring the extinction of the fluorescent solution,487 andRhodamine B has also been used for the determination of gallium in475 J.Liebig and H. Bredehorst, Analyt. Chim. Acta, 1961, 24, 573.476R. N. P. Farrow and A. G. Hill, Talanta, 1961, 8, 116.477 J. A. Dean and C. B. Stubblefield, Analyt. Chem., 1961, 33, 382.478J. Malinowski, D. Dancewicz, and S. Szymczak, Chem. Analit., 1961, 6, 183.479 C. A. Parker, Photoelect. Spectr. Gr. Bull., 1961, 334.48oE. J. Bowen, Photoelect. Spectr. Gr. Bull., 1961, 331.481 J. Eisenbrand, 2. analyt. Chem., 1961, 179, 170.482 J. Eisenbrand and M. Raisch, 2. analyt. Chem., 1961, 179, 352.488 J. Eisenbrand and M. Raisch, 2. analyt. Chem., 1961, 179, 406.484E. N. Haran, J . Sci. Instr., 1961, 38, 273.4 8 5 G .Elliot and J. R. Radley, Analyst, 1961, 86, 62.48sA. I. Cherkesov and T. S. Zhigalkina, Zavodskaya Lab., 1961, 27, 658.487A. K. Babko and Z . I. Chalaya, Zhur. analit. Khim., 1961, 16, 268.4 8 a G . I. Kuchmistaya, Znvodskaya Lab., 1961, 27, 377CARTWRIGHT, WESTWOOD, AND WILSON 435A study has been made of the reaction of selenous acid with 3,3’-diamino-benzidine, which has been adopted for the fluorimetric determination ofsub-microgram amounts of selenium in arsenic. 489The separation and determination of sub-microgram amounts of uraniumin milligram amounts of iron, aluminium, and plutonium has been ~tudied.~~OIn organic analysis fluorimetric methods have been used for the deter-mination of polycyclic aromatic hydrocarbons.491X-Ray methods.The application of X-ray spectroscopy to industry hasbeen described in the Proceedings of an International Conference a t Liege.492Papers presented deal with sample preparation, development of new instru-ments, and applications to numerous determinations, and cover the fields ofX-ray fluorescence, X-ray absorption, and X-ray emission methods.Errors due to sampling in the X-ray fluorescent determination of tita-nium in high-temperature alloy have been inve~tigated~~~3 and X-rayspectroscopy has been applied to the determination of minor constituentsin low-alloy ~tee1.~94Several papers have described the use of X-ray methods in the analysisof elements in petroleum oils. For instance, nickel has been directly deter-mined at a level of 0.1 p .~ . m . ~ ~ ~ and both nickel and vanadium have beendetermined by using added cobalt as an internal standard;496 the methodis said to be especially valuable below concentrations of 2 p.p.m. Sulphurin gasoline oils has been determined by X-ray emission spectroscopy 497in concentrations lower than 0.002%.Absorption Spectroscopy.-Attention is first given to absorption by solu-tions in the ultraviolet and the visible region, and turbidimetry, followedby atomic absorption, infrared absorption, and finally nuclear magneticresonance methods.An enormous volume of work hasagain been published in the field of ultraviolet and visible absorption; onlya few of the papers of more general interest can be included.The pressed disc technique has been found to be useful in the ultravioletregion for samples for which suitable solvents are not available.498 Potas-sium chloride is said to be the most suitable material.The use of ultraviolet spectrophotometry in the evaluation of pharma-ceutically active compounds has been described, and papers published upto October, 1960, have been reviewed.499An investigation has been made of the use of Arsenazo I11 (l&dihydroxy-naphthalene-3,6-disulphonic acid -+ 2,7-bis[ (azo-2)-phenylarsonic acid]) inphotometric analysis.500 The reagent gives colour reactions with a numberUltraviolet and visible absorption.aaeC. A. Parker and L. G. Harvey, Analyst, 1961, 86, 54.4*0 D. G. Boase and J. K. Foreman, Talanta, 1961, 8, 187.lS1 J. H. Chaudet and W.I. Kaye, Analyt. Chem., 1961, 33, 113.4s2 Rev. Univ. Min., 1961, 17, 143.aa3R. F. Stoops and K. H. McKee, Analyt. Chem., 1961, 33, 589.R. E. Michaelis, R. Alvarez, and B. A. Kilday, J . Res. Nat. Bur. Stand., C, 1961,4s6 J. E. Shott, jr., T. J. Garland, and R. 0. Clark, Analyt. Chem., 1961, 33, 506.4e7R. A. Jones, Analyt. Chem., 1961, 33, 71.498 V. A. Shlyapochnikov and V. I. Slovetskii, Optics and Spectroscopy, 1961, 10, 132.4ss J. KritEmar, Pharmazie, 1961, 16, 341.6oo S. B. Savvin, Talanta, 1961, 8, 673.65, 71. 4s5 C. C. Hale and W. H. King, jun., Analyt. Chem., 1961, 33, 74436 ANALYTICAL CHEMISTRYof elements and can be used for the determination of thorium, zirconium,hafnium, uranium, and rare earths, being most selective for thorium,zirconium, and uranium(1v).An investigation has been made of the stability of the curcumin complexused for the determination of b0ron.~O1 Studies were carried out withthe dry complex, and with ethanolic solutions of the complex stored both a t0" and at room temperature.The colorimetric analysis of silica by means of the yellow molybdosilicatecomplex has been critically reviewed,502 and a rapid procedure for thedetermination of total and soluble silica has been given based on studiesof a number of factors affecting the reaction.A comparison has been made of different reducing agents in the deter-mination of phosphorus by the formation of heteropoly- blue.503 Consid-eration is given to the effect of heat, of addition sequence and the choiceof instrument, and of reducing solutions.It has been shown that it isnecessary to strike a balance between the stability of the colour with timeand the magnitude of the extinction coefficient of the heteropoly-blue;established methods must be closely followed since the stability of colourintensity is easily lost. The optimum conditions for the development ofcolour have also been studied in the colorimetric determination of phos-phorus, arsenic, germanium, and sili~on.~O~ It has been shown that theintensity of colour is greatly influenced by the concentrations of bothmolybdate and hydrogen ions.A new colorimetric reagent, Solochrome Violet R.S. (C.I. MordantViolet 5), has been proposed for the micro-determination of molybdenum.505Copper, iron, bismuth, zirconium, cerium, tungsten, and vanadium interferewhen present in ten-fold excess.Belcher and West 506 have studied the cerium( m)-alizarin coniplexan-fluoride reaction and have found that a t an optimum pH range of 5-0-5.2the method may be applied over a wide range of fiuoride-ion concentration.From a study of the interference of 23 selected cations and three anions itwas concluded that practically all serious cationic interference could beovercome by masking agents.I n the case of aluminium, iron(m), chrom-ium(m), and vanadium( v) preliminary extraction with 8-hydroxyquinolinewas necessary, while calcium and beryllium were removed by 8- hydroxy-quinoline and chloroform. The same authors have made a comparativestudy of some lanthanon chelates of alizarin complexan as reagents forfluoride.The lanthanum reagent in aqueous solution a t pH 5.2 was foundto be the most sensitive.Nickel can be determined as the stable brown complex with formald-oxime 508 and the method is said to be slightly more sensitive than thatusing dimethylglyoxime.501 D. E. Williams and J. Vlamis, Analyt. Chem., 1961, 33, 1098.602G. J. S. Govett, Analyt. Chim. Acta, 1961, 25, 69.603R. P. A. Sims, Analyst, 1961, 86, 584.504Teru Yuasa, Reports Govt. Chem. In&. Res. Inst., Tokyo, 1961, 56, 43.606H. Khalifa and S. W. Bishara, 2. analyt. Chem., 1961, 182, 96.50'3R. Belcher and T. S. West, Talanta, 1961, 8, 853.507 R. Belcher and T. S. West, Talanta, 1961, 8, 863.508 Z. Marczenko and K. Kasiura, Chem.Analit., 1961, 6, 353CARTWRIGHT, WESTWOOD, AND WILSON 437A colorimetric method for the determination of microgram quantitiesof water has been described, based on the change in extinction when theKarl Fischer reagent reacts with water.509In the organic field the absorption spectra of acetone and diacetonealcohol have been determined in ethanol,510 and a method for their deter-mination when admixed has been described.Only a small number of papers have appeared on thissubject and it is apparent that analysts in general prefer more direct andreproducible methods where possible. The method, however, has beenreviewed by Peaker 511 particularly for the characterisation of polymers.By using a Spekker absorptiometer the applicability of the process has beenstudied for polystyrene and Perspex.What is termed an " absolutemethod " has been claimed and is based on the measurement of the turbidityat a wavelength for a system where the turbidity is proportional to thereciprocal of .the wavelength. Application to the case of silver bromidesols is claimed to give reasonably good results.512The determination of traces of sulphur below 300 p.p.m. in leaded gaso-line can be carried out by modifying the A.S.T.M. lamp-turbidimetricmethod. In the subsequent determination of the sulphate as bariumsulphate accuracy of under 5% is claimed down to as low as 30 p.p.m.513Elemental sulphur in soils can be analysed consistently in the range 1-7,ug./ml. by an extractive process with acetone and direct measurement at420 mp.Results on a variety of soils agreed with those obtained by otherand longer methods.514In the organic field, hydrazine has been determined down to l O - 4 ~ byoxidation with selenium dioxide in acid solution whereby a selenium sus-pension is produced. Organic sfiabilisers, however, are necessary, and timeof standing, acidity, etc., are all important. An accuracy of about 5%is claimed. 515Traces of water in hydrocarbons have been determined by the turbidityproduced by TiCl, vapour. It is claimed that lo-,% water can be rapidlydetermined by using a calibration curve.518 Cholesterol has been quanti-tatively determined in blood serum by direct addition of sodium ethoxide.A linear relationship holds between the turbidity and the cholesterol con-centration under the conditions given ; results were obtained which wereconsistent with those from longer and less simple meth0ds.~17Recent advances in atomic absorptionspectroscopy have been reviewed and controllable variables and featuresof equipment have been discussed.Atomic absorption methods have been applied to the determination of50s D.A. Otterson, Analyt. Chem., 1961, 33, 450.510A. Basiriski and A. Narebska, Roczniki Chem., 1961, 35, 1131.sllF. W. Peaker, Analyst, 1960, 85, 235.slaE. J. Meehan and W. H. Beattie, Analyt. Chem., 1961, 33, 632.61sR. W. Klipp, Analyt. Chem., 1961, 33, 1912.514 M. G. R. Hart, Analyst, 1961, 86, 472.s15M. R. F. Ashworth, Mikrochim. Acta, 1961, 5 .616 M. Kubinov&, 0.Vilim, and V. Svoboda, Coll. Czech. Chem. Comrn., 1961,26, 1320.s17 G . R. Kingsley and 0. Robnett, Analyt. Chem., 1961, 33, 561.618 J. W. Robinson, Analyt. Chem., 1961, 33, 1067.Turbidimetric.Atomic absorption spectroscopy.438 A N AL Y TI C AL C HE MIST R Ymetals in a wide range of materials ; for example, methods have been describedfor the determination of magnesium in biological materialsY519 zinc in agricul-tural materials,520 lead in ~ r i n e , ~ ~ l and lead in gasoline.522An investigation has been made of the factors affecting the determinationof molybdenum, and the apparatus used has been described.523 I n reducingflames, calcium, strontium, manganese, iron, and sulphate ions in solutioncause different degrees of depression in molybdenum absorption, but all inter-ferences were suppressed by the addition of excess of aluminium chloride.The use of the technique of pressed samples ininfrared spectroscopy has been reviewed.524 A study of the use of alkalihalide discs 525 has shown cases of anomalous behaviour. With benzoic,succinic, and adipic acids and succinimide in potassium bromide and potas-sium chloride discs the anomalies are due to adsorption of the sample on tothe surface of the alkali halide particles.The anomalous behaviour ofl-naphthylacetamide is caused by polymorphism of this substance, whilethe behaviour of succinimide in potassium iodide discs is due to the forma-tion of an addition product.A microtechnique for the study of solids has been described whichpermits sample weights as low as 4 fig.to be cells are constructedhaving windows of diamond or sapphire enabling spectra to be obtained inthe 2-35 micron region.The general application of infrared spectrometry to inorganic substanceshas been reviewed,527 and a comprehensive account has been given of theuse of infrared spectroscopy in the paint field.528 A study has been madeof the reproducibility of infrared band intensities, 529 and suggestions havebeen made for the correlation of results obtained from different instruments.Among particular applications of infrared spectroscopy a study has beenmade of the simultaneous determination of sulphate, nitrate, and nitritein water samples. 530 Dilute samples are concentrated and the interferenceof phosphate ions, carbonate ions, and organic material is suppressed byanion exchange.Water in ethanol has been determined by two methodsJ531 one involvingdilution of carbon tetrachloride for water contents of 0 to 9%, and a directmethod for water contents of 0 to 2%.Water has also been determined byreaction with 2,Z-dimethoxypropane in the presence of methanesulphonicacid catalyst to form acetone, which is then measured.532 Carbonyl com-pounds, basic substances, and salts of weak acids and strong bases interfere.Infrared absorption.519 J. B. Dawson and F. W. Heaton, Biochem. J., 1961, 80, 99.520 J. E. Allan, AnaEyst, 1961, 86, 530.521 J. B. Willis, Nature, 1961, 191, 381.522 J. W. Robinson, Analyt. Chim. Acta, 1961, 24, 451.523D. J. David, Analyst, 1961, 86, 730.524A.A. Boldin and R. F. Vasil'ev, Zauodslcaya Lab., 1961, 27, 819.525A. Tolk, Spectrochim. Acta, 1961, 17, 511.526E. R. Lippincott, F. E. Welsh, and C. E. Weir, AnaEyt. Chem., 1961, 33, 137.527V. V. Klimov. Zavodskaya Lab., 1961, 27, 292.628 Off. Dig. Fed. SOC. Paint !kchnol., 1961, 33.629H. A. Szymanski and D. W. Teloh, Analyt. Chena., 1961, 33, 814.530 I. Citron, Han Tai, R. A. Day, jun., and A. L. Underwood, Talanta, 1961,8,798.S S l P . Ferrer Pi and L. Condal-Bosch, Ajinidud, 1960, 17, 280.532F. E. Critchfield and E. T. Bishop, Analyt. C'hem., 1961, 33, 1034CARTWRIGHT, WESTWOOD, A N D WILSON 439A method has been described for the simultaneous determination ofmethoxy- and ethoxy-gro~ps.~~~ The method is accurate and rapid andis superior to previous methods in that only small samples are required,scrubbing is eliminated, and no interference is caused by sulphur in anyform or in any amount.The use of nuclear magnetic resonancemethods in organic analysis has been reviewed 534 and a guide is given tothe interpretation of the nuclear magnetic spectrum of a single compound.The rapid determination of fluorine in single compounds and mixtureshas been de~cribed.~~o A measuring time of one minute enables the fluorinecontent of a 20 ml. sample to be measured with a relative error of 1% anda detection limit of about 12 mg.of fluorine. With 0.2 ml. samples therelative error is increased to 2% with a detection limit of 3 mg. of fluorine.Nuclear magnetic resonance.10. Electrical methodsUnder this heading are grouped electrodeposition, polarography, radio-chemistry, and mass spectrometry.Polarography accounts for the greatestvolume of published work and this grows yearly. Some idea of the proli-feration of work on this subject can be gleaned from the review by Wawzo-nek 535 which quotes 710 papers on organic polarography alone during theperiod 1958-1960; many of these directly or indirectly have analyticalsignificance. In view of their probable importance a short sub-section onthe newer techniques such as a.c., cathode ray, and allied methods has beenincluded. Owing to their greater sensitivity and resolution and the avail-ability of appropriate instruments they are gaining ground. Since theyhave extended the limits of determination from the 1 0 - 5 ~ region of classicalpolarography to 10-7-10-s~, they are well suited to the examination ofhighly purified materials, as required by some of the newer technologies.Here alsoonly direct analytical applications have been considered.Much has beenpublished in non-analytical journals and may escape notice. Radioactiva-tion techniques have increased and some elegant procedures for trace elementsare reported.Mass spectrometryhas been used in combination with radiochemistry to determine traces, andwith gas chromatography to determine the components of complex mixtureswith success.Electrodeposition, however, is generally on the decline and has largelybeen replaced by other more rapid, more sensitive, and more elegantmethods.Electrodeposition.-Little new work has appeared on this technique inthe last two years.A review of electroanalysis has foreshadowed thecontinual decline of this method in favour of the more convenient coulo-metric methods.536Radiochemical applications are legion and are increasing.There have been several combinations of technique.633 D. M. W. Anderson and J. L. Duncan, Tulunta, 1961, 8, 1.684 J. C. Martin, J . Chem. Educ., 1961, 38, 286.636 S . Wawzonek, Analyt. Chem., 1960, 32, 1 4 4 ~ .636D. D. De Ford, Analyt. Chern., 1960, 32, 3 1 ~ 440 ANALYTICAL CHEMISTRYCopper has been determined in lead-base and tin-base alloys by con-trolled potential methods in amounts as low as 0.2yo in an acid solutioncontaining tartaric acid. Antimony under 1.5% does not interfere.Silverand bismuth codeposit, and procedures are given for dealing with them.537Lead and tin have been determined in lead-tin solders; 538 the lead isdeposited at pH 7-86 with a change in pH near the end-point t o 4-8-53by addition of hydrochloric acid. Hydrazine is added to avoid depositionof lead dioxide on the anode. Tin is then deposited by making the solutionstrongly acid and increasing the deposition voltage; the methods have beensuccessfully applied to N.B.S. solder 127A and B.C.S. white metal 177.Developments of these methods have enabled consecutive determinationsof copper, antimony, lead, and tin in lead-base 539 and tin-base 540 alloysto be made. Mercury has been determined to &lyo in mercurial andorgano-mercurial pesticides by deposition at a silver-plated platinum-gauzecathode.541 A composite procedure for the analysis of aluminium bronzesutilises the deposition of copper from an ammonium nitrate solution, thoughother metals are determined by other meth0ds.~~2 The separation ofpraseodymium and neodymium under a variety of conditions has beeninvestigated in a lithium citrate electrolyte.543Applications have been made to the separation and determination ofradioactive elements in EDTA solution. Lead-210 and bismuth-210 havebeen deposited from extremely dilute solutions on a nickel cathode at pH 3.5in nitric acid, counting methods being used to determine the yield. Polo-nium was best isolated by internal electrolysis using a silver electrode. In5 ml.1 mc. of Po was recovered with an efficiency of 98%.544 Electrolyticseparations of trace amounts of uranium, neptunium, plutonium, andamericium have been studied in a variety of acidic electrolytes and a simpleprocedure for isolating plutonium from the other elements is described; itis deposited directly at high current density after addition of oxalic acidto prevent interference from iron.545Polarograpb.-This technique continues to grow in popularity andaccounts for more publications than any other direct electrochemical methodof analysis. In a report such as this, a comprehensive assessment is impos-sible and only a selection of applications of possible interest to analystscan be made.Recent general reviews have discussed methods and instru-mentation.546 Special reviews have appeared on organic onindustrial uses, 547 and on applications to food analysis.548 Several theo-retical papers have appeared which discuss diffusion processes at the drop-537 B. Alfonsi, Analyt. Chim. Acta, 1960, 22, 431.53aB. Alfonsi, Analyt. Chirm. Acta, 1960, 23, 375.639 B. Alfonsi, Analyt. Chim. Acta, 1961, 25, 274.640 B. Alfonsi, Analyt. Chim. Acta, 1961, 25, 374.641F. Vernon, Analyt. Chem., 1961, 33, 1435.542 M. Freegarde and B. Allen, Analyst, 1960, 85, 731.643E. I. Onstott, Analyt. Chem., 1961, 33, 1470.s44V. Verbersik, 2. analyt. Chem., 1960, 175, 405.645 A. G. Samartseva, Atomnaya Energiya, 1960, 8, 324.646 D. N. H u e , Analyt. Chem., 1960,32,137~; H.W. Niirnberg and M. von Stackel-647 W. Biichler, 2. analyt. Chem., 1960, 173, 17.648 H. Woggon, Ernuhrungsforschung, 1960, 5, 119.berg, J . Electroanalyt. Chem., 1961, 2, 181, 350CARTWRIGHT, WESTWO 0 D , AND WILSON 441ping-mercury electrode at various drop rates, 549 at rotating electrodes, 550and a t cylindrical rni~ro-electrodes.~~1 The factors which affect the limitof sensitivity of the dropping-mercury electrode have been studied and itis concluded that, in electronic instrumentation, capillary " noise " is amajor factor.552A new polarograph has been devised for solutions of high resistance 553in which the iR effect is effectively eliminated, and which is suitable fornon-aqueous solutions; and a new polarising unit, with scanning unit andcurrent compensator, suitable for conventional and derivative polarography,has been de~cribed.5~~ For student use a simple semi-automatic polaro-graph has been devised.555Graphite 556 and carbon paste 557 electrodes have been successfully usedfor analysis of several inorganic and organic systems and an accuracy com-parable with that of the dropping-mercury electrode has been claimed.The wide-bore electrode, used for determining dissolved oxygen, has beenimproved to cope with a wide range of flow rates.558 Reference electrodes innon-aqueous systems have been investigated and it was concluded that theS.C.E.is frequently not ~uitable.55~ A number of cells, devised for specialapplications, have been described and include a cell for flowing solutions,56oa microcell for hanging-drop voltammetry, 561 and a versatile, detachablethree-component cell.562Uraniumhas been studied in EDTA solutions over a wide range of pH,563 and inconcentrations down to 1 0 - 4 ~ at pH >6.5 in the presence of excess offerric ions and several other elements, with a fluoride base electrolyte.564A simple procedure for determining technetium in fission products con-sists of deposition from an alkaline citrate base into mercury drops whichthen fall into a lower layer of carbon tetrachloride. The activity producedby technetium-99 a t 140 kev is determined by y-spe~trometry.~~~ Ananodic procedure for determining manganese uses an alkaline tartrate solu-t i ~ n . ~ ~ ~ By pre-electrolysis at - 1.50 v (S.C.E.) under cathodic conditionsM.P. Simmonin, J . Chim. phys., 1960, 57, 161; R. Tamamushi, S. Momiyama,and N. Tanaka, Analyt. Chim. Acta, 1960, 23, 586.550 W. Vielstich, 2. analyt. Chem., 1960, 173, 84.551E. Morgan, J. E. Harrar, and A. L. Crittenden, Analyt. Chem., 1960, 32, 756.552 W. D. Cooke, M. T. Kelley, and D. J. Fisher, Analyt. Chem., 1961, 33, 1209.553P. Arthur, P. A. Lewis, N. A. Lloyd, and R. K. Vanderkam, Analyt. Chem.,554M. T. Kelley, D. J. Fisher, and H. C. Jones, Analyt. Chem., 1960, 32, 1262.555G. W. Drake and C. B. Johnston, J. Chem. Educ., 1960, 37, 240.556P. J. Elving and D. L. Smith, Analyt. Chem., 1960, 32, 1849.557 C. Olson and R. N. Adams, Analyt. Chim. Acta, 1960, 22, 582.558 R. Briggs and G. Knowles, Analyst, 1961, 86, 603.559 R.C. Larson, R. T. Iwamoto, and R. N. Adams, Analyt. Chim. Acta, 1961, 25, 371.5 6 0 W. J. Blaedel and J. H. Strohl, Analyt. Chem., 1961, 33, 1631; K. Koyama,561W. L. Underkofler and I. Shah, Analyt. Chem., 1961, 33, 1966.562D. K. Roe and C. J. Nyman, Chemist-Analyst, 1960, 49, 27.563 T. T. Lai and T. L. Chang, Analyt. Chem., 1961, 33, 1193; D. G. Davis, ibid.,564A. H. Verbeek, J. T. Moelwyn-Hughes, and E. T. Verdier, Analyt. Chim. Ada,565 D. L. Love and A. E. Greendsle, Analyt. Chem., 1960, 32, 780.56eH. A. Catherino and L. Meites, Analyt. Chim. Acta, 1960, 23, 57.Numerous papers have appeared on determination of metals.1961, 33, 488.Analyt. Chern., 1960, 32, 1053.p. 492.1960, 22, 570442 ANALYTICAL CHEMISTRYall the manganese is reduced to Mn(n).On reducing the voltage to -0.7 vthe manganese is oxidised and the diffusion current at 0.36 v (S.C.E.)is measured. Only iron interferes if the ratio of iron to manganese con-centrations is >lo. A simple procedure for manganese in glasses involvesfusion with ammonium fluoride and oxalic acid and then dissolution inhydrochloric acid and addition of ammonium hydroxide and sulphite; asuitable reduction wave was obtained.567 Niobium has been determined inhighly alloyed steels. After dissolution in acid and hydrolysis the niobicacid is separated and fused with potassium hydroxide. After adjustmentof the pH to 1.9 in the presence of EDTA it wave was obtained withEL = -0.65 v (mercury pool), which was free from interference from allother metals except molybdenum.568 Separation of niobic acid by a solvent-extraction method was used to determine this element in titanium ores andpigments.569 Until recently arsenic(m) in alkaline solution has not beenconsidered to be reducible; however, in a lithium hydroxide-lithium chloridesolution a well-defined wave was obtained which was claimed to be suitablefor analytical purposes.570 Potassium iodide has been reported as a goodbase electrolyte for arsenic(m) and gives linearity between id and concentra-tion over the range 0.06 and 0.8 mm~le/litre.~~l A simple procedure fordetermining antimony in refined lead has been claimed to be applicabledown to 10 p.p.m. After removal of lead as sulphate the solution is polaro-graphed.Tin tends to interfere if present in s i w c a n t amounts and theEs. values for arsenic and bismuth are suEiciently removed from that ofantimony [-0.32 v (S.C.E.)] tb avoid interference.572 Europium has beendetermined down to 20 p.p.m. in monazite and samarskite. After disso-lution, precipitation of lead, and separation of rare earths by conventionalmeans, the rare-earth oxides were dissolved in hydrochloric acid and ignited.The residue was dissolved in 0.1M-ammonium chloride. The wave a t-0.67 (S.C.E.) was used to determine the europium content ; apparentlythere were no interferences. 573No difficultyarises from a high ratio of nitrate to nitrite in an acid citrate buffer at pH 2.After destruction of the nitrite with hydrazoic acid and addition of uranylions the nitrate was determined.574 A method based on the formation ofnitroso-2-naphthol from nitrite and 2-naphthol has been used for determiningnitrites in bri11es.57~ Thiosulphate in photographic gelatin has been deter-mined down to 6 x l O - ( j ~ with a mean error of &5%.After the gelatinhad been warmed with 0-1N-potassium nitrate at 50" direct polarographygave a wave at -0.50 v (S.C.E.).576 Difficulties arose if iodides or tetra-667 M. s. Zakharov, A. G. Stromberg, and G. G. Rodnova, Zavodskaya Lab., 1960,26, 163.s69L. A. Balchin and D. I. Williams, Analyst, 1960, 85, 503.670 W. B. Swam, J. F. Hazel, and W. M. McNabb, Analyt. Chem., 1960, 32, 1064.671T. Matsumae and R. Nakashima, Analyt. Chim.Acta, 1961, 24, 192.572 V. T. Athavale, R. G. Dhaneshwar, M. M. Mehta, and M. Sundaresan, Analyst,s78 V. T. Athavale, R. G. Dhaneshwar, and M. M. Mehta, Analyt. Chim. A&, 1960,674R. Annirio and J. E. McDonald, Analyt. Chern., 1961, 33, 475.576 J. H. Dhont, Analyst, 1960, 85, 144.s7aV. Stefan, Chem. prumysl, 1960, 10, 126.Nitrite has been determined in the presence of nitrate.668D. J. Brindley, Analyst, 1960, 85, 877.1961, 86, 399.23, 71CARTWRIGHT, WESTWOOD, AND WILSON 443thionates were present. Studies of the thiocyanate ion have shown thatit produces a wave in 0-1N-perchloric acid with E, = +0.205 v (S.C.E.)suitable for analysis.577 Complex ions formed between thiocyanate ionsand mercury(@ have been studied, and the formulae of such ions and theirformation constants have been evaluated. 578 Sulphide and elementarysulphur have been estimated in viscose fibres by simple procedures.Totalsulphur was determined by treatment with sodium hydroxide to convertsulphur into sulphide, followed by addition of EDTA and polarographingfrom -0.2 to -1.0 v (S.C.E.). Elementary sulphur was determined simi-larly after removal of hydrogen sulphide and carbon disulphide by treatmentwith dilute sulphuric a ~ i d . ~ 7 ~I n the plastics field styrene monomer was rapidly determined in poly-styrene resins by dissolution in alcohol using tetrabutylammonium chloridein 75% alcohol solution;580 phthalate, fumarate, and maleate esters do notinterfere. Styrene has also been determined by conversion into the nitro-site with sodium nitrite and acetic acid. After addition of sodium acetatea well-defined wave [Et = -0.27 v (S.C.E.)] was pr0duced.5~1 A pro-cedure for determining terephthalic acid in mixtures of phthalic acidisomers down to O.lyo with accuracy utilised a O-lM-lithium hydroxide baseelectrolyte.A wave was produced by terephthalic acid at -1.93 v(S.C.E.).582 Dimethyl and dibutyl phthalates have been determined inpropellants where nitroglycerine interferes. Reduction of the “ nitrogly-cerine ” by metallic zinc or titanous chloride in alcohol was followed byaddition of tetramethylammonium hydroxide to precipitate metals beforepolarography. The first of the two waves at -1.65 v (S.C.E.) was used forquantitative purposes. Good results were obtained up to 2.39% of dimethylphthalate and 6.95% of dibutyl phthalate.583 Aromatic hydrocarbons havebeen studied in concentrated solutions of trifluoroacetic acid. Perylene,tetracene, anthracene, pyrene, 3,4-benzopyreneY and 1,Z-benzanthraceneall give two waves on reduction. The first wave is a reduction of the hydro-carbon ion which is rapidly followed by protonation, and the second wave isa reduction of the proton complex.584 Amino-compounds such as tyrosine,tryptophan, and phenylalanine have been determined by selective nitrationto their nitro-derivatives;5a5 full details are given for each of these com-pounds, singly and in mixtures. An indirect procedure for a-amino-acidsinvolved their reaction at controlled pH with copper phosphate.Afterremoval of excess of copper compound the copper chelates formed wereconverted into 1 : 1 copper-EDTA complexes which were determined polaro-graphically. The method was claimed to be accurate to 3% at 1 0 - 3 ~concentration, but capable of detecting 2 x 10 - 6 ~ q~antities.58~ Cystine577R. A. Plowman and I. R. Wilson, Analyst, 1960, 85, 222.578 C. J. Nymam and G. S. Alberts, Analyt. Chem., 1960, 32, 207.570R. P6cenJi and V. NedvZidovS, Chem. prumysl, 1960, 10, 165.s80 W. M. Apes and G. C. Whitnack, AnaZyt. Chem., 1960, 32, 358.681V. i%divec and J. Flek, Coll. Czech. Chem. Comm., 1960, 25, 1223.582M. E. Hall and R. C. McNutt, AnaZyt. Chem., 1960, 32, 1073.583 J. Townend and E. Macintosh, Analyst, 1961, 86, 338.684 W. I. J.Aalbersberg and E. L. Mackor, Trans. Paraday SOC., 1960, 56, 1351.686D. Monnier, J. Vogel, and P. E. Wenger, Andyt. Chim. Acta, 1960, 22, 369.686 W. J. Blaedel and J. W. Todd, AnaZyt. Chem., 1960, 32, 1018444 ANALYTICAL CHEMISTRYand cysteine have been estimated directly in wool hydrolysates preparedwith sulphuric acid, by using cathodic and anodic waves respectively, withan accuracy of -+O-1 mg. on 30 mg., by means of a standard additionmethod.587 Thioethanolamine and its disulphide have been determined inthe presence of each other to within 2% at the level of 7-5 x 10-6M-con-centration, with one species in hundred-fold excess. At pH 7.4, thioethanol-amine gives a wave at -0.42 v and its disulphide at -0.62 v (S.C.E.).58*A number of hydroxy-triphenylmethane dyes have been shown to give a2-step reduction at pH 7 which is suitable for estimation and has beenapplied to aurines, eriochromes, chromoxanes, and naphthochrome~.~~~The behaviour of anumber of metal ions in liquid ammonia has been studied by using lithiumperchlorate as base electrolyte.590 Ethylenediamine has also been reportedto give good curves for many metal species, sodium nitrate or lithium chloridebeing used as electrolyte. 591 Similarly N-methylacetamide with tetra-ethylammonium bromide was satisfactory and a mercury pool made a suit-able reference electrode.592 Benzene-methanol mixtures were used todetermine several metal naphthenates, tallates , and octanoates in paintdriers. 593 Anodic studies of aromatic and heterocyclic hydrocarbons havebeen made in acetonitrile by using a rotated platinum electrode. The effectsof substitution on E, values were shown and techniques were devised foranalyses of mixtures of these compounds.594Several reviews onthese rapidly expanding fields have appea,red including recent generaldevelopments, 5g5 oscillographic applications ,5969 597 and alternating currentmethods.598 Much theoretical study has been promoted and is increasing.A full examination of variation in frequency and its effects on the symmetryand height of the peaks produced has been made, and the effects of variableson the analytical use of the peaks have been discussed.599A modification t o an existing d.c.polarograph has been made whichpermits it to be used as an a.c.instrument, The a.c. unit is separate andis made non-floating by earthing the negative side. When a mercury poolwas used accurate placement of the dropping-mercury electrode was neces-sary t o obtain reproducibility. High sensitivity was claimed.600 A.c.voltammetry using harmonic measurements has been demonstrated, 601 andPolarography in non-aqueous media is developing.A.c., cathode ray, and other polarographic methods.687 L. Benikk, 2. analyt. Chem., 1960, 175, 244.688 E. C. Chevalier and W. C. Purdy, Analyt. Chim. Acta, 1960, 23, 574.aE9M. Matrka, F. NavrBtil, and C. Figar, Chem. prumysl, 1960, 10, 129.a9oW. Hubiski and M. Dabkowska, Analyt. Chem., 1961, 33, 90.aglG. Schober and V. Gutmann, 2. analyt. Chem., 1960, 173, 2.aSsD.E. Sellers and G. W. Leonard, Analyt. Chem., 1961, 33, 334.69sE. J. Kuta, Analyt. Chem., 1960, 32, 1065.696G. W. C. Milner, Chimia (Switz.), 1960, 14, 106.ss6G. F. Reynolds, 2. analyt. Chern., 1960, 173, 65; M. Herrmann, ibid., p. 21.697 G. C. Whitnack, J . Electroanalyt. Chem., 1961, 2, 110.6g8H. Schmidt, 2. analyt. Chern., 1960, 173, 73.H. H. Bauer, J . Electroanalyt. Chem., 1961, 2, 66.6o0 W. F. Head, Analyt. Chim. Acta, 1960, 23, 297.601 H. H. Bauer, J . Electroanalyt. Chem., 1960, 1, 256; D. E. Smith and W. H.J. W. Loveland and G. R. Dimeler, Analyt. Chem., 1961, 33, 1196.Reinmuth, Analyt. Chem., 1961, 33, 482CARTWRIGHT, WESTWOOD, AND WILSON 445solid electrodes have been successfully applied with a lower limit of2.7 x 1 0 - 6 ~ for many systems.6o2Lead, cadmium, and zinc have been determined in large excess of in-dium 603 in a 0.5~-ammonium nitrate base.Good separation of the leadand cadmium peaks was obtained but the latter tended to be affected bythe indium peak. In M-phosphoric acid the indium peak disappearedowing to complex formation.Studies of isomeric organic compounds, e.g., o-, m- and p-nitrophenols 604and rn- and p-nitr~anilines,~~~ have shown the resolving power of thistechnique.Increasing use has been made of the cathode-ray polarograph in metal-lurgical problems. Very pure silicon was analysed, and procedures for10-6% of lead, cadmium, iron, copper, nickel, thallium, bismuth, and zincwere described.606 Lead has been determined in zirconium and its alloysdown to 10 p.p.m.607 Copper and iron have been determined in high-purity aluminium.608 Iron and steels have been analysed for copper,lead,609 and tin.610Anion determinations include that of cyanide 611 in O.lM-sodiumhydroxide down to 0.05 pg./ml., and iodate and periodate in a number ofbase electrolytes.612 Several explosives have been examined and simul-taneous determinations have been devised such as that of N.G.and D.N.G.,61Sand of R.D.X. and P.E.T.N.614The limits of applicability and sensitivity of the square-wave methodhave been discussed.615 It has been adapted to the determination of copperand lead in indium arsenide down to 0.1 p.p.m. of copper and 0.2 p.p.m.of lead.616 Plutonium down to 3.7 x 10-6M-concentration has also beendetermined in acid solution.617 Uranium in sea water has been determinedby using an extraction process followed by examination in a perchloric-tartaric acid supporting electrolyte.618A number of studies 619 have been made of the anodic stripping techniquewherein the species is stripped out at high current density. The speciesthen redissolves anodically during a voltage scan and the current peakproduced gives a measure of the concentration of the original species. The602 D. E. Walker, R. N. Adams, and A. L. Juliard, Analyt. Chem., 1960, 32, 1526.603 T. Takahashi and H. Shirai, Talanta, 1960, 5, 193.604T. Takahashi and H. Shirai, Tdanta, 1961, 8, 177.605 J. Tirouflet and E. Laviron, 8. analyt. Chem., 1960, 173, 43.606F. A. Pohl and W.Bonsels, Mikrochim. Acta, 1960, 641.607 R. T. Clark, Analyst, 1960, 85, 245; D. F. Wood and H. A. Nichols, ibid., p. 139.608 J. S. Hetman, Analyt. Chim. Acta, 1960, 22, 394.609 P. H. Scholes, Analyst, 1961, 86, 116.H. Scholes, Analyst, 1960, 85, 392.611 J. S. Hetman, J . Appl. Chem., 1960, 10, 16.61aA. Berka and J. Doleial, Analyt. Chim. Acta, 1961, 24, 476.613 J. S. Hetman, Talanta, 1960, 5, 267.614 J. S. Hetman, Analyt. Chem., 1960, 32, 1699.615 F. von Sturm, 2. analyt. Chem., 1960, 173, 11.616 V. J. Jennings, Analyst, 1960, 85, 62.617K. Koyama, Analyt. Chem., 1960, 32, 523.G. W. C. Milner, J. D. Wilson, G. A. Barnett, and A. A. Smales, J . Electroanalyt.619 W. H. Reinmuth, Analyt. Chem., 1961, 33, 185; I. Shah and J. Lewinson, ibid.,Chem., 1961, 2, 25.p.187446 ANALYTICAL CHEMISTRYmethod has been applied to nickel in a thiocyanate medium and it wasclaimed that concentrations down to 5 x 1 0 - s ~ could be analysed.620By using a platinum or gold electrode, with a rotated mercury plated plati-num electrode, thallium and lead have been determined a t lo-'M levelin a 0.1M-nitrate solution.621 Iodide down to 4 x 1 0 - 8 ~ concentrationhas been determined at a silver electrode by a corresponding cathodicprocess.622New techniques which have received attention and are suitable forultra-small amounts of reducible species include pulse polarography, inwhich the square-wave voltage is replaced by polarising pulses of shortand the hanging-drop technique which has been applied to thedetermination of 0.01 p.p.m.of cadmium in uranium salts.624Radiochemistry.-It is impossible in a small space adequately to presentthe progress which has occurred in two years. Activation analysis hasincreased in popularity but the isotopic tracer method is still the mostwidely applied. Many applications do not appear in journals concernedwith analysis and hence may escape attention, particularly as they are oftenpresented a.s minor aspects of larger or differently oriented work.Several reviews have been published including a general review ofnucleonics, activation analysis, 626 radiochemical analyses of multiple-labelled sub~tances,~2' a valuable collection of individual reviews onseparate elements,628 and microchemical methods used in the U.K.AtomicWeapons Research Establishment over the past 6 ~ears.62~ Numerousmodifications in apparatus and techniques have occurred. Past neutron-activation analysis using 14 Mev neutrons produced by bombarding atritium target has been advocated as an alternative to pile irradiation whereappropriate. 630 An a-counter, suitable for determining plutonium insolution,631 and a large proportional counter spectrometer for studyingradioactive samples of very low activity,G32 have been described. Anall-Teflon flow cell for continuous monitoring of 45Ca in effluent streamshas been devised, though some adsorption by heavy metals may restrictits use.633Applications involving neutron activation continue to increase, particu-larly for minute traces of elements in metals.Morris and Killick havedevised a number of straightforward procedures which follow irradiationwith thermal neutrons in B.E.P.O. Osmium and indium in palladium and620M. M. Nicholson, Analyt. Chem., 1960, 32, 1058.621 S. Bruckenstein and T. Nagai, Analyt. Chem., 1961, 33, 1201.6 2 a I . Shah and S. P. Perone, Analyt. Chern., 1961, 33, 325.623 G. C. Barker and A. W. Gardner, 2. analyt. Chem., 1960, 173, 79.624 W. Kerntila, E. Rakowska, and 2. Kublik, J. Electroanalyt. Chem., 1960, 1, 206.625 W. Wayne-Mehke, A d y t . Chem., 1960, 32, 1 0 4 ~ .626A. H. W. Aten, Chem. Weekblad, 1960, 56, 94; D. Mapper, Chimia, 1960, 14, 241.627 N. Getoff, Osterr. Chem.-Ztg., 1960, 61, 101.628 Nat. Acad. Sci. Nuclear Sci., 1960, Nos. 3008, 3009, 3014, 3021, 3023, 3024, 3026,629 R.G. Monk and J. Herrington, Analyt. Ch.im. Acta, 1961, 24, 481.630R. F. Coleman, Analyst, 1961, 86, 39.631 J. T. Byrne and G. A. Rost, Analyt. Chern., 1961, 33, 758.632 J. T. Holloway, D. C. Lu, and D. J. Zaffarano, Rev. Sci. Instr., 1960, 31, 91.633 W. J. Blaedel and E. D. Olsen, Analyt. Chem., 1960, 32, 789.3027, 3028; 1961, 3018, 3025, 3030, 3032, 3033, 3035, 3036CARTWRIGHT, WESTWOOD, AXD WILSON 447platinum,634 and gold 635 and palladium 636 in platinum were determinedby using carrier techniques. The causes of possible interferences andmethods of avoiding them were discussed. Manganese in steels was deter-mined by a very short time of irradiation (10 minutes), thus avoiding sig-nificant activation of any of the other constituents.Owing to its highcapture cross-section (a 3 13.4 barns) an appreciable activity was quicklyacquired. By leaving the sample for 4 hours, species such as 52V, ‘Wu,51Ti, 94mNb, and 1OlmMo had decayed away, and 56Mn was counted by itsy-emission above 1.5 Mev.637 High-purity aluminium for use in reactorcores has been analysed for cadmium 638 by using a short time exposure.After irradiation the cadmium was separated by ion-exchange methods andprecipitated with carriers; a sensitivity of 1 part in lo9 parts was claimed.Copper, cadmium, nickel, tellurium, and zinc were determined in high-purity selenium.639 Owing to the short half-life of 65Ni (2.56 hours) a rapidprocedure was essential. Each metal was determined separately by its#$activity after precipitation with isotopic carriers.Similar procedureshave been used for determining minute traces of metals in rocks and meteor-ites. A radium separation from rocks was devised for silver and thallium,based on precipitation and electrodeposition, and counting as iodate andchromate respectively.640 The sensitivity claimed was 0.03 p.p.m. forsilver and 0-04 p.p.m. for thallium. Carriers and solvent extraction methodsbeing used to isolate the active species, tantalum 641 and rhenium 642 weresimilarly determined. Scandium 643 and vanadium 644 have also been deter-mined in rocks and meteorites in connexion with studies of the SkaargaardIntrusion of E. Greenland; cadmium 645 was also determined on the sameproject.The methods, which involved y-counting, gave close agreementwith results obtained for standard G1 and W1 rocks. The procedure €orvanadium was perforce very rapid since the isotope 52V has a half-life ofonly 3.76 minutes. Selenium and tellurium have also been determined inmeteorites after an irradiation of 1 week. The 75Se is readily detected anddetermined by its three intense y-photopeaks, and 127Te by its p-activity.646In the biological field, sodium, potassium, and phosphorus have been deter-mined down to 10-lo, and 10-lo g., re~pectively.~~7 Strontium hasbeen determined in alfalfa, rye-grass, milk powders, and bone ash by neutronactivation using the 87mSr isotope for measurement by its /I-activity. Onlya few hours’ activation was ne~essary.~~g634D.F. C. Morris and R. A. Killick, Talanta, 1961, 8, 129.635 D. F. C. Morris and R. A. Killick, Talanta, 1961, 8, 793.636 D. I?. C. Morris and R. A. Killick, TaZarLta, 1961, 8, 601.637 P. Bouten and J. Hoste, Talanta, 1961, 8, 322.638E. Ricci and W. D. Mackintosh, Analyt. Chem., 1961, 33, 230.63sA. I. Williams, Analyst, 1961, 86, 172.640 D. F. C. Morris and R. A. Killick, Talanta, 1960, 4, 51.641D. F. C. Morris and A. Olya, Talanta, 1960, 4, 194.64a D. F. C. Morris and F. W. Fifield, Talanta, 1961, 8, 612.643 D. M. Kemp and A. A. Smales, Analyt. Chim. Acta. 1960, 23, 410.644 D. M. Kemp and A. A. Smales, Analyt. Chim. Acta, 1960, 23, 397.64sL. I. Bilefield and E. A. Vincent, Analyst, 1961, 86, 386.646 U. Schindewolf, Geochim. Cosmochim.Acta, 1960, 19, 134.1 3 ~ ’ H. J. M. Bowen and P. A. Cawse, Analyst, 1961, 86, 506.648 B. A. Loveridge, R. K. Webster, J. W. Morgan, A. M. Thomas, and A. A. Smales,Analyt. Chim. Acta, 1960, 23, 154448 ANALYTICAL CHEMISTRYOther activation procedures reported include the determination offluoride in sodium chloride utilising the 19F(n,a)16N reaction by fast neu-t r o n ~ , ~ ~ ~ and the determination of iodine in silicon down 0.005 p.p.m. bya distillation procedure, absorption of the iodine into sulphite solution,and precipitation as silver iodide.65o Counting was done on a 2n counter.Ion-exchange techniques are frequently involved in the separation ofradioactive species. A separation scheme covering 35 elem.ents and usinga Dowex 50W cation-exchange resin has been put forward.651 Of theseover 30 are extracted to >goyo and 3 to >SOYo yields.Palladium, gold,mercury, and silver, however, cannot be accommodated in this scheme. Anumber of papers have been devoted to the determination of fission pro-ducts from uranium and plutonium. Tellurium was separated fromuranium on a Dowex-2 anion resin from a phosphoric acid solution withalmost quantitative yield.652 95Zn and 95Nb were removed from uraniumfission products by absorption on an anion-exchange resin Dowex 1-X4from a 0-3~-hydrofluoric acid solution, with yields of >99.6yo, and wererelatively free from other elements. 653 Irradiated plutonium metal afterdissolution was examined for 95Zr, g5Nb, l03Ru, 147Nd, and Pr. Plutoniumwas removed from the solution by an anion-exchange resin from stronglyacid solution and these elements were separated by precipitation techniques(zirconium and rhodium) and extraction techniques (niobium and ruthen-i ~ m ) .~ ~ ~ In the determination of radio-iodine in fission products, otheractivities were removed in one process by the cation-exchange resin Dowex50x8, and this was followed by an ion-exchange process based on silveriodide according to the scheme AgI + I* + AgI* + I, which occurs rapidly;the silver iodide was then counted.655 gOSr has been determined indirectlyin milk by a rapid method involving removal of alkali and alkaline-earthmetals by a cation-exchange resin. By use of an anion-exchange resin the90Sr daughter product, was then eluted with dilute acid, precipitated asoxalate, and counted in an anti-coincidence p-counter.Very good agree-ment with established methods was claimed. 656There has been an increased use of separation procedures using solventextraction, particularly by Maeck and his co-workers. Neptunium has beenextracted effectively as the tetra-alkylammonium trinitrate complex intoisobutyl methyl ketone from uranium fission-product mixtures, 657 and zincby extraction of the diethyldithiocarbamate complex into ethyl acetate.The latter indicated 658 that the fission yield of 72Zn on thermal neutronirradiation of 235U was 2.6 x 2-Thenoyltrifluoroacetone has beenused to extract zirconium from fission products as a complex in xylene and649 0. U.Anders, Analyt. Chem., 1960, 32, 1368.650T. Nozaki, H. Baba, and H. Araki, Bull. Chem. SOC. Japan, 1960, 33, 320.G51 W. J. Blaedel, E. D. Olsen, and R. F. Buchanan, Analyt. Chem., 1960, 32, 1866.662 L. Wish, Analyt. Chem., 1960, 32, 920.653A. C. Leaf, Talanta, 1960, 6, 265.654 J. W. T. Meadows, G. M. Mattack, and G. B. Nelson, Talanta, 1960, 6, 246.655 W. J. Maeck and J. E. Rein, Analyt. Chem., 1960, 32, 1079.s66 C. Porter, D. Cahill, R. Schneider, P. Robbins, W. Perry, and B. Kahn, Analyt.667 W. J. Maeck, G. L. Booman, M. C. Elliott, and J. E. Rein, Analyt. Chem., 1960,668 W. J. Maeck, M. E. KUSSY, and J. E. Rein, Analyt. Chem., 1961, 33, 235.Chem., 1961, 33, 1306.32, 605CARTWRIGHT, WESTWOOD, AND WILSON 449it is claimed to be highly selective from fluoride solution, and to be moreefficient than any other extractant .659 Frequently the extraction techniqueis combined with isotopic dilution. Phosphorus has been determined as32P by addition of potassium phosphate as carrier and extracted as phospho-molybdic acid in butanol-chloroform mixtures. The activity is extractedback into ammonia solution and is converted into magnesium pyrophosphatefor counting.660 Dithizone has been used for extraction of zinc 661 betweenpH 7-5 and 8.5 and of mercury 662 down to 10-6-10-7 g./ml.The theoryof the extraction process has been considered and the dependence on pHand other factors for dithizone has been el~cidated.~63 Uranium has beendetermined in sea water by a method involving addition of a stable isotopeand extraction into chloroform after complexing with 8-hydroxyquino-line. 664 Addition of 235U and mass-spectrometer measurements were alsoinvolved. A check with a fluorimetric method gave consistent results andconfirmed a value of 3.3, & 0.08 pg./ml.for water in the English Channel.A considerable number of papers involving the normal isotope-dilutionanalysis have continued to appear. A simple rapid method for iodine inthe presence of chloride and bromide involved addition of iodine and potas-sium iodide and shaking with carbon tetrachloride ; the extracted activitywas measured.665 Boron down to 0.001 pg. in silicon has been determinedby addition of a l o g - tracer. By electrolysis through a cation-exchangemembrane and determining the isotopic abundance with a mass spectro-meter this minute trace of boron was determined.666 235U in feedstocksolutions of uranium fuel has also been determined by isotopic dilutionfollowed by mass spectrometry; Z3,U and natural uranium were used astracers but the use of 233U gave more satisfactory re~ults.6~7 Tungstenhas been determined at low concentrations in high-alloy steels; afterhomogeneous precipitation from nitric acid-hydrogen peroxide solutionthe tungsten was determined either by counting or by spectrophotometry.668A variety of applications using liquid-scintillation methods continuesto appear. 95Zr and 95Nb have been readily determined by using a liquidscintillation spectrometer owing to ready resolution of the p-particle spectra,thus avoiding the necessity for corrections for self-absorption involved inother methods.669 Tritium in water and urine has been estimated downto 0.005 pc./litre by using low- background vessels. 670 Coloured solu-tions 671 such as Methyl Red, Bromothymol Blue, and blood digest have659 S. F. Marsh, W. J. Maeck, G. L. Booma.n, and J. E. Rein, Analyt. Chena., 1961,33. 870.660H. H. Ross and R. B. Hahn, Talanta, 1961, 8, 575.661 J. Star$ and J. RhiiEka, Talanta, 1961, 8, 296.662 J. RGiiEka and J. Star$, Talanta, 1961, 8, 535.663 J. Rhiidka and J. Starp, Talanta, 1961, 8, 228.66* J. D. Wilson, R. K. Webster, G. W. C. Milner, G. A. Barnett, and A. A. Smales,666M. D. Morachevskaya and B. V. Ptitsfn, Zavodslcaya Lab., 1960, 26, 269.666 D.C. Newton, J. Sanders, and A. C. Tyrrell, Analyst, 1960, 85, 870.667 R. K. Wester, D. F. Dance, J. W. Morgan, E. R.. Preece, L. J. Slee, and A. A.Smales, Analyt. Chim. Acta, 1960, 23, 101.66* G. Leliaert, J. Hoste, and Z . Eeckhaut, Rec. Trav. chim., 1960, '79, 557.669 J. D. Ludwick, Analyt. Chem., 1960, 32, 607.670F. E. Butler, Analyt. Chem., 1961, 33, 409.671 R. T. Herberg, Analyt. Chem., 1960, 33, 42, 1468.Analyt. China. Acta, 1960, 23, 505.450 ANALYTICAL CHEMISTRYbeen estimated by suitable procedures, and radioactive substances havebeen determined by suspension in a gel scintillator; in this way 90Sr, g o y ,36Cl, 22Na, la3Ba, 63Ni, W, and 3H have been determined.672Mass Spectrometry.-A recent review 673 indicates the developmentswhich have occurred, particularly in the United States of America and theU.S.S.R., since 1958.A two-stage mass spectrometer, devised for preciseabundance measurements in nuclear reactor technology, incorporates im-proved optics and a fast pulse-counting technique for detecting positiveions.674 Modifications to a commercial instrument produce a signal whichis a direct measure of the amount of material charged to it.675 Combina-tions of mass spectrometry and gas chromatography have appeared inwhich a conventional magnetic field spectrometer is coupled directly to achr0matograph.67~, 677Plutonium has been determined in irradiated uranium by an isotopicdilution method using 2 4 2 P ~ as a tracer with preliminary separation by anion-exchange technique, and measurement of the recovered plutonium bya MS5 ~pectrorneter.~’~ Uranium and plutonium have been determineddown to 10-8 g.in a device in which the ion beam is detected by an electron-multiplier and the pulses are accumulated in a modified pulse-analyser.The accelerating voltage is synchronised with the pulse sorter so that thedata can be printed out directly on a recorder.679 Very small quantitiesof lead, of the order of ( 1 p.p.m., in rocks and motor oils have beendetermined by a volatilisation procedure using 212Pb tracer to determineyields. BSOCorre-lations of mass spectra with structure have been made for a number ofaromatic alcohols and phenols, and spectral features suitable for qualitativeand quantitative analyses are discussed .681 Similar correlations for alde-hydes and acids,682 aliphatic esters,683 aromatic esters,684 and fluorinatedcyclic compounds 685 have been reported.Spectra of thiols and disulphideshave also been correlated in an investigation to determine the componentsresponsible for odour changes in beef.686Cyclo-pentane and cyclohexane derivatives in gasoline have been resolved, 687 andMost applications have occurred, of course, in the organic field.Numerous applications in the petroleum industry are of interest.6 7 2 s . Helf, C. G. White, and R. N. Shelley, Analyt. Chem., 1960, 32, 238.673V. H. Dibeler and R. M. Rees, Analyt. Chem., 1960, 32, 2 1 1 ~ .674 L. A. Dietz, C. F. Pachucki, J. C. Sheffield, A. B. Hance, and L. R. Hanrahan,‘375H.E. Lumpkin and J. 0. Beauxis, Analyt. Chem., 1960, 32, 1815.6 7 6 L . P. Lindeman and J. L. Annis, Analyt. Chem., 1960, 32, 1742.6 7 7 A. A. Ebert, Analyt. Chem., 1961, 33, 1865.6 7 8 R . K. Webster, A. A. Smales, D. F. Dance, and L. J. Slee, Analyt. Chim. Acta,679 G. W. Barton, L. E. Gibson, and L. F. Tolman, Analyt. Chem., 1960, 32, 1599.6 8 o R . R. Marshall and D. C. Hess, Analyt. Chem., 1960, 32, 960.681 T. Aczel and H. E. Lumpkin, Analyt. Chem., 1960, 32, 1819.6 8 z T . Aczel and H. E. Lumpkin, Analyt. Chem., 1961, 33, 386.683 J. H. Benyon, R. A. Saunders, and A. E. Williams, Analyt. Chem., 1961, 33, 221.6’34E. M. Emery, Analyt. Chem., 1960, 32, 1495.68sR. J. Majer, J . Appl. Chem., 1961, 11, 141.a8sE. J. Levy and W. A. Stahl, Analyt. Chem., 1961, 33, 707.687 H. E. Howard and W. C. Ferguson, Analyt. Chem., 1961, 33, 1870.Analyt. Chem., 1960, 32, 1276.1961, 24, 371CARTWRIGHT, WESTWOOD, AND WILSON 451the effectiveness of removal of mercaptans in naphthas can be readilymonitored.The presence of naphtheno-pyridine, -quinoline, and -carbazoles inpetroleum residues has been established and determined and the resultsagree closely with those obtained by ultraviolet spectroscopy.689 By useof a combination of high-temperature gas chromatography and massspectrometry, 67 components were identified. These included normalparaffins, and cyclopentyl and cyclohexyl derivatives. l7 An investigationof asphalt gave evidence of compounds from mass 24 to about 1900; exam-ination of the fragment spectra indicated that aromatic and heterocyclicnuclei were predominant.690 The fragments obtained in the mass spectraof dialkylboranes have been identified by using compounds labelled with1OB and de~terium.~~l An accurate method of determining tetramethyl-lead and tetraethyl-lead occurring together in gasoline has been claimed tobe much more rapid than chemical methods and to be suitable for routinework. 139211. Thermal methodsStress continues to be laid in both differential thermal and thermo-gravimetric analysis on the careful design of apparatus and strict controlof conditions necessary to ensure reproducible results. Garn,693 in a surveyof current differential methods, discusses sample holder design, sample sizeand geometry, thermal environment, and the influences of restricted diffu-sion and control of the atmosphere over the sample. Garn and Kessler 694indicate the advantages of analysis of effluent gases in thermal methods.The main application of the methods continues to be to inorganic materials,and an example of careful differential thermal analysis is the determinafionof the temperature of transformation between two forms of calcium oxide.695An apparatus has been described for differential thermal analysis at lowtemperatures. 696 There is a growing appreciation of uses in organic analysis.Chesters and Thompson 697 have carried out differential thermal analysesof a number of polysaccharides and have shown that a number of closelyrelated compounds, e.g. , amylose and amylopectin, give widely differingthermograms. They suggest that the technique may be used for poly-saccharide characterisation and for general identification of organic com-pounds. Routine differential thermal analysis of explosives is carriedout 698 in samples of less than 10 mg. by using a specially designed cell andfurnace.688 W. P. Hoogendonk and F. W. Porsche, Amlyt. Chem., 1960, 32, 941.689 C. L. Lau, Analyt. Chim. Acta, 1960, 22, 239.690R. J. Clerc and M. J. O'Neal, AnaZyt. Chem., 1961, 33, 380.691 C. 0. Wilson and I. Shapiro, Analyt. Chem., 1960, 32, 78.692 H. E. Howard, W. C. Ferguson, and L. R. Snyder, Analyt. Chew,., 1960, 32, 1814.693 P. D. Gem, AnaEyt. Chem., 1961, 33, 1247.694 P. D. Garn and J. E. Kessler, Analyt. Chem., 1961, 33, 952.695 B. V. S. Subba Rao, D. S. Datar, and Abde Mi, J . Sci. Ind. Res., India, B696 I. Proks and V. Sigke, C'hem. Zvesti, 1961, 15, 309.697 G. Chesters and S. 0. Thompson, Science, 1961, 133, 275.1961, 20, 347.R. N. Rogers, Microchem. J . , 1961, 5, 914: ANALYTICAL CHEMISTRYThermogravimetric methods of analysis have been reviewed by Lukas-zewski and Redfern899 who deal with the requirements of the thermalbalance, applications, and techniques. Guiochon 700 discusses errors indeductions from thermogravimetric measurements which are due to lackof appreciation of the conditions of thermal decomposition and of theinfluence of the products of decomposition. A thermogravimetric study ofmetal-gas reactions has been carried out with magnesium and aluminium.701The method is used widely to study the suitability of gravimetric procedures.The behaviour of plutonium and several of its compounds has been investi-gated 702, 703 and ranges of thermal stability have been determined. Theprecipitation of magnesium, potassium, and lead with 5-nitrobarbituric acidhas been studied, and conditions for its use as a gravirnetric reagent havebeen established;704 it has also been used in the determination of ethylene-diamine and quinine. 705 Determination of calcium, strontium, and bariumin a single sample of their oxalates by an indirect thermogravimetric tech-nique has been described,706 based on losses of weight of extraneous moisture,of water of crystallisation, and of carbon monoxide and dioxide.Since differential thermal analysis, thermogravimetric analysis, and dif-ferential thermogravimetric analysis (in which rate of gain or loss in weightis recorded) all require the same basic type of apparatus with controlledrate of heating over a wide range, and since the information derived fromea,ch is complementary to, and can best be interpreted in conjunction with,that derived from the others, it would seem that simultaneous determinationof rate of change in weight and in temperature is bound to be increasinglya'pplied. An apparatus for this purpose has been patented.707Thermometric titrations, in which the end-point is determined by a sharpchange in the shape of the curve connecting temperature of solution andvolume of titrant added, enable a wide variety of reagents to be used, andare unaffected by precipitation or gel formation. They have been used inthe titration of zinc, cadmium, and mercuric salts with aqueous ammoniaand sodium hydroxide 708 and in determining calcium in the presence ofmagnesium, by titration with ammonium oxalate, in limestone analysis. '09P. F. S. CARTWRIGHT.J. V. WESTWOOD.D. W. WILSON.699 G. M. Lukaszewski and J. P. Redfern, Lab. Practice, 1961, 10, 469, 552, 630.' 0 ° G. Guiochon, Analyt. Chew&., 1961, 33, 1124.701M. M. Markowitz and D. A. Boryta, Analyt. Chem., 1961, 33, 949.702 G. R. Waterbury, R. M. Douglass, and C. F. Metz, Analyt. Chem., 1961, 33, 1018.703 I. S. Sklyarenko and T. M. Chubukova, Zhur. analit. Khim., 1960, 15, 706.704A. Berlin and R. J. Robinson, Analyt. Chim. Acta, 1961, 24, 224.705A. Berlin and R. J. Robinson, Analyt. Chim. Acta, 1961, 24, 319.706 L. Erdey, F. Paulik, G. Svehla, and G. Liptay, 2. analyt. Chem., 1961,182, 329.707 F. Paulik, J. Paulik, and L. Erdey, B.P. Appln. 865,073/25.9.57.708 M. P. Ben-Yrtir, Trans. Chalmers Univ. Technol., Gothenburg, 1961, No. 236.'09 J. Jordan and E. J. Billingham, jun., Analyt. Chem., 1961, 33, 120