ANALYTICAL CHEMISTRY.IN this year's Report, absorptiometric and radiochemical methods, whichwere not considered in the last Report, are now reviewed. All reference tospectroscopic methods has been omitted, but will be dealt with in the nextReport. Research on absorptiometric methods has been so extensive thatit has only been possible to cover the inorganic applications. It is hopedthat it will be possible to review organic applications in the next Report.The most notable events of general interest to analytical chemists in thiscountry during 1955 were the lectures, sponsored by the Society for AnalyticalChemistry, and given at various centres in England, by Professor Schwarzen-bach of Zurich1 and Professor J. Heyrovskjr of Prague.2 The speakersdealt in general terms with the subjects each had pioneered, complexonesand polarography, and which have had such a great impact on the develop-ment of analytical chemistry in recent years.In July a Symposium on Microchemistry was held in Vienna under theauspices of the Austrian Microchemical Society.About 600 delegates frommost parts of the world were present and some 90 papers were read.3 Atthe opening ceremony, the Feigl Prize was awarded to Dr. H. Weisz for hiscontribution to microchemistry in developing the new ring-oven technique.*GeneralThe design and functioning of various components are discussed and methodsfor assessing the sharpness and fineness of knife edges and their adjustmentare described. Reference is also made to balances used for special purposes.Ulbricht has described a detailed mathematical investigation concerningthe effect of air buoyancy on the accuracy of weighing.Corrections forbuoyancy are recommended which can be calculated from curves andformulze. Pfundt has described a riderless microbalance. A mechanicaldevice is used for adding weights from 1 mg. upwards and a projection scalegives the 0 - 1 mg. readings. The left-hand pan may be removed for addingsmall objects. Two models have been made, for maximum loads of 20 g.and 10 g. respectively. The latter balance has an automatic tare device, aseparate rider for checking sensitivity, and an external sensitivity adjustment.Both models have separate beam compartments.Corrosion tests have been carried out on brass weights coated with twodifferent thicknesses of tin-nickel alloy, and the results have been comparedwith those obtained when other materials were used.8 The weights with theA useful paper has been published which deals with analytical balances.G. Schwarzenbach, Analyst, 1955, 80, 713.J.Heyrovskf, ibid., in the press.Mikrochimica Acta, 1956, in the press.A m . Reports, 1954, 51, 336.D.S.I.R. (N.P.L. Notes Appl. Sci., 1954, No. 7).H. Ulbricht, 2. analyt. Chem., 1955, 145, 161.P. H. Bigg and F. H. Burch, Brit. J . Appl. Phys., 1954, 5, 382.' P. Pfundt, Mikrochim. Acta, 1954, 539340 ANALYTICAL CHEMISTRY.heavier coating (25 p) showed the same resistance as highly polished stainless-steel weights. The stability of mass was about the same as that of austeniticstainless-steel and rhodium-plated brass weights.Weights made from 80120nickel-chromium showed slightly less resistance in highly corrosive atmo-spheres. For the fractional weights austenitic stainless-steel was the best,followed by zirconium, tantalum, aluminium, and titanium.The factors which must be considered when preparing standards forvolumetric glassware have been detailed.g The units of volume, standardtemperature, construction and checking of apparatus, delivery procedure,drainage time, and the delivery of non-aqueous liquids are discussed.Kawamura lo has found that hydrogen peroxide mixed with variousmineral or organic acids effects the rapid dissolution of steels and ferro-alloys which are normally resistant to attack.For example, ferro-tungsten,rapidly dissolves in hydrogen peroxide-hydrofluoric acid, and stellite andferro-vanadium in hydrogen peroxide-oxalic acid. Rapid methods of steelanalysis are discussed using this new opening-out treatment.A new apparatus for wet oxidation with sulphuric and nitric acid hasbeen described l1 in which the volatile products are condensed and returnedto the flask. A great saving in time and reagents is claimed.DeFord l2 has discussed the reliability of calculations based on the lawof chemical equilibrium and has indicated the factors which must be con-sidered in order to avoid serious errors.A historical account of the development of organic elementary analysishas been given by van der Wal.13The problems which arise when complexing agents are used in titrimetricanalysis have been disc~ssed.1~ From potentiometric and colorimetricstudies of the reactions involved, it is concluded that, unless polydentatereagents are used, the formation of lower complexes, particularly near theend-point when the ligand concentration is low, leads to significant errors.Various methods for detecting the end-point are considered.Kuznetsov 15 has studied the theory involved in selecting organicco-precipitants. In certain cases it was found possible to predict suitablereagents, e.g., in the precipitation of zinc thiocyanate with methyl-violet,but it was necessary to select non-salt forming organic compoundsempirically.A systematic study of several metal-diethyldithiocarbamate complexeshas been made by Bode.16 He examined the spectra and the effect of pHand masking agents on the distribution between carbon tetrachloride andthe aqueous phase.Several selective determinations are suggested as aresult of this work.Irving and Rossotti 17 have discussed the factors which determine theanalytical usefulness of reagents, with particular reference to the effect of0 D.S.I.R. (N.P.L. Notes Appl. Sci., No. 6).lo K. Kawamura, Jap. Analyst, 1953, 2, 347, 417.l1 J. Pien, Ann. Fals. Fraudes, 1954, 47, 266.l2 D. D. DeFord, J. Chern. Edztc., 1954, 31, 460.l3 A. A. van der Wal, Chem. Weekblad, 1954, 50, 829.14 A. E. Martell and S. Chaberek, Analyt. Chern., 1954, 26, 1692.l5 V. I. Kuznetsov, Zhur. analit. Khim., 1954, 9, 199.l6 H.Bode, 2. analyt. Chem., 1954, 143, 182.l7 H. Irving and H. S. Rossotti, Analyst, 1955, 80, 245BELCHER, BEVINGTON, STEPHEN, AND WEST. 341structural modifications on reagents of low selectivity. Since insufficientphysicochemical information is available, it is concluded that sensitivitytests are the best approach to assessing the potentialities of a reagent.Thiosemicarbazones of several aldehydes and ketones have been examinedas reagents for all the common metals at various pH levels.l* Silver,mercury, and copper formed coloured precipitates in all cases and cobaltgave red solutions. Some of the compounds were found suitable for thedetermination of mercury and copper.Several substituted dithiocarbamates have been examined as analyticalreagents.lg The most interesting appears to be ammonium tetramethylene-dithiocarbamate, for much smaller amounts of buffer are required to main-tain the correct pH range than with the sodium compounds. This enablesthe total volume to be considerably reduced.The properties and applications of the eight known reagents availablefor the gravimetric determination of nitrate have been reviewed byWilliams .mThe properties of derivatives of ' oxine lD continue to arouse interest.Sensitivity tests on 8-hydroxy-5-nitroquinoline indicated that it should bemore selective than oxine, but unsatisfactory results were obtained whenquantitative experiments were carried out.21 The behaviour of the reagentis discussed from the standpoint of its absorption spectrum and otherphysical characteristics .The analytical properties of 8-hydroxy-5-, -6- , and -7-trifluoromethyl-quinolines have been examined and acid dissociation constants of the firsttwo have been determined.22 Their behaviour is similar to that of thecorresponding methyl compounds, but the 7-compound does not form aprecipitate with any of the ions which have been tested.It is concludedthat this anomalous behaviour is due to ortho-effects. The 5-methyl-7-nitroso-, Z-methy1-5-nitroso-, 7-allyl-5-nitroso-, and 5-bromo-7-(2 : 3-di-bromopropy1)-derivatives of 8-hydroxyquinoline have been examined asanalytical reagents.% Some of these derivatives are more selective thanoxine and the factors which may be responsible are discussed.ReagentsPrecipitants.-A new reagent, purpureocobaltic chloride, for the gravi-metric determination of tungsten has been proposed by Dupuis.% Theparatungstate is formed at pH 5-1-64, and the metatungstate at pH24-3*1.The paratungstate gives more accurate results and can be dis-solved in ammonia solution for colorimetric measurement. However, wheniron is present it is necessary to precipitate the metatungstate to avoidinterference. At other pH ranges other tungstates are precipitated, butare not suitable for gravimetric analysis since their composition is not alwaysconstant.S. S. G. Sircar and S. Sathpathy, J. Indian Chem. SOC., 1954, 31, 450.l9 H. Malissa and E. Schoffman, Mikrochim. Acta, 1955, 187.2o M. Williams, Ind. Chemist, 1954, 30, 594.21 H.Irving, R. G. Hollingshead, and G. Harris, Analyst, 1955, 80, 260.22 R. Belcher, A. Sykes, and J. C. Tatlow, J., 1955, 376.23 R. G. W. Hollingshead, Analyt. Chim. Ada, 1955, 12, 201; Chevn. and I n d ,24 T. Dupuis, Mikrochim. Acta, 1955, 851.1954, 1260; Research, 1955, 8, 9342 ANALYTICAL CHEMISTRY.McCune and Arquette 25 have examined hexamniinocobaltic chloride asa reagent for the separation of triphosphoric and pyrophosphoric acids, butprecipitation occurred at all pH ranges. With trisethylenediaminecobalticchloride, however, only the triphosphate was precipitated at pH 3.5, whilstat pH 6-5 only pyrophosphate was precipitated. Trimetaphosphate andtetrametaphosphate are not precipitated. Unfortunately, it was notpossible to precipitate triphosphate in the presence of pyrophosphate, forrecoveries were incomplete and co-precipitation occurred.An examinationof similar complex precipitants, however, might yield useful results and helpto solve this old problem in analytical chemistry.Arsanilic acid has been proposed as a reagent for the gravimetric deter-mination of bismuth.26 Only sodium, potassium, ammonium, and acetateions are mentioned as not interfering. Chloride, phosphate, and tartratemust be absent.Duval and Wadier 27 recommend 5 : 5-dimethylcyclohexane-1 : 3-dioneas a specific reagent for univalent mercury. The composition of the pre-cipitate is variable, however, and it is necessary to redissolve it in nitric acidand complete the determination by one of the usual methods.Diallyldithiocarbamidohydrazine has been examined as a reagent for thedetermination of nickel and copper.28 Nickel is precipitated in the pH range8-1-8.7, and copper at 2-5-36, hence it is possible to determine both metalsin mixtures.The nickel complex is weighed, but that with copper is ignitedto the oxide, dissolved in acid, and determined iodometrically.Nickel and copper can be determined gravimetrically after precipitationwith resorcylaldoxime.29 Although precipitation of the metal complexesoccurs at different pH ranges, separation is not possible. Many other ionsdo not interfere, however, and the reagent has been used successfully for thedetermination of copper in brass.o- and 9-Chlorophenoxyacetic acid and p-chloro-m-tolyloxyacetic acidhave been used for the gravimetric determination of thorium.30 Separationfrom cerite earths can be achieved with one precipitation, the first being themost effective of these reagents.Thorium may also be determined in thepresence of small amounts of rare earths and bismuth by using benzene-phosphonic acid as reagent.31 Precipitation is quantitative at a very lowpH range. The reagent is not very selective, however, and appears to havelittle advantage over the host of existing reagents now available.Colorimetric.-Solochrome Brilliant Blue B (B.C. Index No. 723) hasbeen proposed for the colorimetric detennination of beryllium.32 It issuitable for the range 0.2-1.6 pg. per ml. A method has been developedfor the determination of beryllium in air.Bromoanilic acid (3 : 6-dibromo-2 : 5-dihydroxy-$-benzoquinone) hasbeen examined as a reagent for the colorimetric determination of calcium.3325 H.W. McCune and G. J. Arquette, Analyt. Chem., 1955, 27, 401.26 A. Musil and R. Pietsch, 2. analyt. Chem., 1955, 144, 347.27 C. Duval and C . Wadier, Compt. rend., 1955, 240, 433.28 N. K. Dutta and K. P. S. Sarma, Science and Culture, 1956, 20, 397.29 A. K. Mukherjee, Analyt. Chim. Acta, 1955, 13, 334.30 N. Eswaranarayana and Bh. S. V. R. Rao, J . Sci. Ind. Res., India, 1954, B, 13,657.a1 C. V. Banks and R. J. Davis, Analyt. Chim. Acta, 1955, 12, 418.32 J. H. Wood, Mikrochim. Acta, 1955, 11.33 L. Erdey and I. Jankovits, Acta Chim. Acad. Sci. Hung., 1954, 4, 245BELCHER, BEVINGTON, STEPHEN, AND WEST.343After addition of a known amount of the reagent the precipitate is filteredor centrifuged off and the residual colour of the solution is measured at530 my in a Pulfrich photometer.Michal and Zyka 34 have used tetraethylthiuram disulphide as a colori-metric reagent for the determination of copper. An intense yellow-browncolour is produced with an absorption maximum at 445 my. The methodis highly selective. Mercury(@ also forms a complex and in its presenceexcess of reagent should be used but there is no interference since themercury complex is colourless.as areagent for the colorimetric determination of copper, an intense yellow colourbeing produced in neutral or hydrochloric acid solutions. Only metalswhich give colours in a hydrochloric acid medium interfere ; nitrates,chlorides, acetates, tartrates, and phosphate have no effect even in a 1000-fold excess.Copper has also been determined colorimetrically by the formation of achloroform-soluble complex with 2-isatoxime methyl ether.36 The methodis highly selective.Mukherjee 37 has proposed the use of ethylenediaminebis-sulphosalicyl-aldehyde and p-aminosalicylic acid as sensitive reagents for the colorimetricdetermination of ferric iron.The latter is the more sensitive but severalions, notably uranyl, copper, nickel, chromate, and molybdate, interfere.The reagent can be used over a wide pH range and the colour is very stable.Thorium may be determined colorimetrically by means of the intenseviolet colour produced when it is treated with ~armine-red.~~ Of the usualelements associated with thorium, only ferric iron interferes. A pH of 2.5and wavelength of 560 mp are the most suitable conditions for measurement.Thiobenzamide has been recommended by Gagliardi andR.B.Inorganic Qualitative AnalysisThe use of thioacetamide in place of hydrogen sulphide, particularly insemimicro-qualitative analysis, continues to gain favour and many papershave been published in recent years extolling the advantages which accruefrom the use of this reagent. However, in a timely paper, Lehrman andSchneider point out that the indiscriminate replacement of hydrogensulphide by thioacetamide in conventional qualitative schemes can lead todifficulties which have not been considered in earlier studies of the reagent.Thus, if oxidising agents like iron(m), arsenate, or nitric acid are present,some reagent may be destroyed, leaving an insufficient concentration insolution to effect complete precipitation of the metal sulphides; the oxid-ation of thioacetamide gives rise to sulphate ions which favour the loss ofthe alkaline-earth cations.During the hydrolysis of thioacetamide, acetateions are formed which lower the hydrogen-ion concentration of the solutionby buffer action. Under these conditions, the Group IV cations may be34 J. Michal and J. Zyka, Chem. Listy, 1954, 48, 1043.35 E. Gagliardi and W. Haas, Mikrochim. Acta, 1954, 593.36 L. Divis and J. Skoda, Chem. Listy, 1954, 48, 539.37 A. K. Mukherjee, Analyt.Chim. Acta, 1955, 13, 268, 273.38 N. Eswaranarayana and Bh. S . V. R. Rao, 2. analyl. Chem., 1955,146, 107.39 L. Lehrman and P. Schneider, J . Chem. Educ., 1955, 52, 474344 ANALYTICAL CHEMISTRY.precipitated as sulphides. Then, before the Group I11 cations can beprecipitated as hydroxides, the excess of thioacetamide must be removed insuch a way that no objectionable ions (e.g., sulphate) are formed in solution.Each disadvantage has been studied experimentally and a procedure hasbeen developed to overcome them; the only unsatisfactory feature of themethod is that about 25% of the zinc is precipitated along with the Group I1sulphides. Of the Group IV cations, only zinc behaves in this way. Thelithium hydroxide reagent recommended by Holness and Trewick for theseparation of the copper and arsenic groups has been criticised by Jamesand Wo~dward.~~ They claim that if the activity of the hydroxyl ion is themain consideration in the choice of a suitable reagent, then lithium hydroxidehas no advantage over sodium or potassium hydroxide. This point isproved in a critical study of the factors affecting the separation, and in place .of the lithium hydroxide reagent, a 06N-SOhtiOn of potassium hydroxide isrecommended.It is not necessary to have potassium nitrate present in thereagent solution if the sulphides are precipitated from hot solution with useof a low flow-rate of hydrogen sulphide; sulphides precipitated in this waydo not readily form colloids. If mercury and the Group IIB cations arepresent together, some mercuric sulphide dissolves in the alkali, and merccrymust be looked for in both sub-groups.Tin@) must be oxidised beforeprecipitation with hydrogen sulphide because of the low solubility of tin@)sulphide in 06N-pOtaSSiUm hydroxide. Heath 41 describes an alternativeto the conventional procedure for the separation and identification of theGroup I1 cations. The precipitate of metal sulphides is treated with hydro-chloric acid which gives an initial separation. Further sub-groups areobtained which make the identification of the elements present an easymatter.Weisz 42 has applied his versatile ring-oven technique to a qualitativeexamination of the materials used in the fabrication of some Egyptianarchaeological specimens.By a suitable sampling procedure, sufficientmetal is removed from the specimen to provide a drop of solution whichcan be analysed by the ring-oven methods. Bank and van der Eijkaconfirm Weisz’s results for the qualitative examination of a drop of solutionby the ring-oven method. Arsenic and mercury are now included in thescheme of analysis. Verma and Paula have developed a spot-test pro-cedure for the detection of cadmium in the presence of copper, lead, and tin.This test is more effective when ring-oven techniques are used.Smith and Shute45 have made a critical study of the separation andidentification of aluminium in the normal scheme of qualitative analysis.Difficulty was experienced in obtaining a satisfactory test for aluminium byusing ammonium aurintricarboxylate (“ aluminon ”) because of incompleteseparation of the aluminium from iron and chromiym.A modified schemehas thus been recommended which uses NN-di(hydroxyethyl)glycine(“ Versene, Fe3+ specific ”) to overcome interference from iron. Highlysatisfactory results are obtained.40 C. F. James and P. Woodward, Analyst, 1955, 80, 825.41 P. Heath, ibid., 1954, 79, 781.42 H. Weisz, J . Chem. Educ., 1955, 32, 70.43 C. A. Bank and W. van der Eijk, Chern. Weekblad, 1955, 51, 351. ** M. R. Verma and S. D. Paul, AnaZyst, 1955, 80, 399.45 S. B. Smith and J. M. Shute, J . Chem. Educ., 1965, 32, 380BELCHER, BEVINGTON, STEPHEN, AND WEST. 345Numerous qualitative tests have been proposed during the year. Holz-becher 46 described the fluorescence reaction of aluminium with salicyl-aldehyde and 2-hydroxy-1-naphthaldehyde and 18 derivatives of thesecompounds.With salicylidene-o-aminophenol, 0-005 pg. of aluminium isdetectable at a limiting concentration of 1 in lo8. Patrovsky4' uses thisreagent for the detection of gallium. The fluorescence due to aluminium ismasked by addition of sodium fluoroborate. Rhodamine-B is also used forthe detection of gallium ; 48 conditions are obtained which make the reactionspecific for as little as 0.01 pg. of Ga2+. Gagliardi and Theis 49 have examinedseveral simple monoazo-dyes derived from 1-naphthol as reagents for thedetection of magnesium in alkaline solution. Benzoin is used as a fluorescentreagent for the detection of germanium; the reaction is not particularlysensitive.Pribil and Michal 51 use quercetin for the identification of vanad-ium; the reagent is sensitive to 2 pg. of vanadium in 5 ml. of solution.Cobalt is identified in the presence of nickel 52 by means of the deep bluecolour formed with a solution containing the monothiophosphate ion,P0,S3-. The test is applicable to the solution of cobalt and nickel obtainedby normal group analysis. Theis 53 describes a spot test for beryllium,using Chromazurol-S, which is sensitive to 1 pg. of beryllium in 5 ml. ofsolution; Chloroplumbic acid 54 has been used for the direct detection ofpotassium in the presence of a large number of cations, including sodiumand lithium ; rubidium and caesium interfere. Sodium tetraphenylboron isrecommended for the detection of potassium in systematic qualitativeanalysis ; 55 ammonium salts, which interfere, are completely removed by asuitable procedure before carrying out the test.Rush and Rogers 56 haveexamined the effect of the substrate (filter-paper) on two catalytic spot-tests for copper. A 10-fold variation in sensitivity is observed between22 grades of paper, the ashless grades in general being the most sensitive.Seely 57 has used modified spot-test techniques to detect several commonions in dust particles of 10-10 to 10-15 g.Little new work has been published in the field of qualitative anionanalysis. A systematic scheme based on Feigl's separation into soluble andinsoluble zinc salts has been recommended for use on the micro- and semi-micro-~cales.~~ Wendlandt and Bryant 59 describe a more reliable test forcarbon dioxide than the conventional one using lime-water.The reagentis a solution of sodium methoxide in methanol, which gives a voluminouswhite precipitate of sodium methyl carbonate with carbon dioxide. Wirth46 S. Holzbecher, Coll. Czech. Chem. Comm., 1954, 19, 241.(7 V. Patrovsky, Chem. Listy, 1954, 48, 537.H. Onishi, Analyt. Chem., 1955, 27, 832.49 E. Gagliardi and M. Theis, 2. analyt. Chem., 1955, 144, 264.N. Appala Raju and G. Gopala Rao, Nature, 1955, 175, 167.51 R. Pribil and J. Michal, Chem. Listy, 1954, 48, 621.52 S. K. Yasuda and J. L. Lambed, J . Chem. Educ., 1954, 31, 572.53 M. Theis, 2. analyt. Chem., 1955, 144, 192.64 W.Rodziewicz and J. Szychlinski, Roczniki Chem., 1954, 28, 657.55 R. F. Muraca, H. E. Collier, J. P. Bonsack, and E. S. Jacobs, Chemist-Analyst,6 6 R. M. Rush and L. B. Rogers, Mikrochim. Ada, 1955, 821.6 7 B. K. Seely, Analyt. Chem., 1955, 27, 93.6 8 F. de Leo, R. Indovina, and A. Bellino, Ann. Chim. (Italy), 1954. 44, 859.69 W. W. Wendlandt and J. M. Bryant, Chemist-Analyst, 1955, 44, 52.6O C. M. P. Wirth, zbid., 1954, 43, 101.1954, 43, 102346 ANALYTICAL CHEMISTRY.has developed a colour test for borates using polyvinyl alcohol; the reagentis added to an acidic solution of the borate and a drop of iodine is introduced ;a deep blue colour results. Feigl and Hainberger 61 have developed a spot-test for the detection of sodium dithionite, using an ethanolic solution of9-dinitrobenzene ; in the presence of strong aqueous ammonia an immediateorange coloration is produced with 3 Fg.of dithionite.Inorganic Gravimetric AnalysisThe discovery of sodium tetraphenylboron as a reliable precipitant forpotassium is one of the most important advances in inorganic analysis inrecent years. Titrimetric procedures are available for the evaluation ofpotassium tetraphenylboron but the gravimetric method is the generallypreferred one. Sykes 62 has reviewed most of the important analytical usesof sodium tetraphenylboron. Sporek and Williams have made a criticalexamination of the published procedures for the precipitation of potassiumtetraphenylboron ; readily filterable precipitates are obtained when thereaction mixture has a final acidity greater than 0 * 2 ~ , but it is then necessaryto keep the temperature at 0" to prevent decomposition of the reagent.Cluley 64 has also studied the available methods for the determination ofpotassium with sodium tetraphenylboron, and he recommends two methods,involving precipitation at pH 2 and pH 6.5 respectively. The proceduresare applied to the determination of potassium in glasses and refractories.The direct determination of potassium by use of fluoroboric acid isdescribed by Mana~evit,~~ who has investigated the effect of temperature,solvent, and foreign ions on the precipitation of potassium fluoroborate.High results are obtained in the presence of ammonium, barium, and sulphateions; calcium and aluminium interfere when present together, but notsingly. A 25-fold excess of sodium can be tolerated in determinations of20-200 mg.of potassium.Conditions for an accurate gravimetric determination of micro-amountsof sodium as antimonate in the presence of large amounts of potassiumhave been worked out ; 66 the precipitation is effected in 25-30% ethanol.Lithium in small amounts is determined in the presence of other alkalimetals by extraction of lithium chloride with n-pr~panol.~~ The residueobtained after removal of the solvent is dissolved in a mixture of hexamine,acetone, and water, and the mixture is treated with a reagent containingpotassium ferricyanide. A yellow precipitate of a complex lithium potassiumhexamine ferricyanide is obtained.Two papers of interest in the field of gravimetric analysis deal with thehygroscopic properties of precipitates 68 and the thermogravimetry ofrhodium.69 Methods have been described for the rapid determination of61 F.Feigl and L. Hainberger, Mikrochim. Acta, 1955, 105.A. Sykes, I n d . Chem. Mfr., 1955, 31, 245, 305.63 K. Sporek and A. F. Williams, Analyst, 1955, 80, 347.134 H. J. Cluley, ibid., p. 354.6s H. M. Manasevit, Analyt. Chem., 1955, 27, 81.66 K. S. Cheshev, Zhur. analit. Khim., 1954, 9, 239.6 7 C. F. Forster, Analyst, 1954, 79, 629.68 H. Amano, J . Chem. SOC. Japan, 1954, 75, 499.6s C. Duval, P. Champ, and P. Fauconnier, Analyf. Chim. Acta, 1955, 12, 138BELCHER, BEVINGTON, STEPHEN, AND WEST. 347thorium in 0re~,70 the determination of chromium as K,CrpF5,H,0,7f andthe determination of bismuth as the 8-hydroxyquinolme complex.72Japanese workers 73 have investigated numerous binary and tertiary systemsin the application of quantitative procedures without preliminary separations.Conductivity measurements have shown 74 that barium sulphate is notprecipitated from aqueous solutions until a concentration product of1.59 x lo-* (about 160 times the solubility product) is reached; spon-taneous formation of nuclei then occurs. The morphology of bariumsulphate has been studied by means of electron micro~copy.~~ Reactiontemperature and concentration of reagents have a considerable effect on theform of the precipitate which is characteristic for any set of reaction con-ditions.Benedetti-Pichler 76 considers that the rate of precipitation and theparticle size of a precipitate may be appreciably affected by trace impuritiesin the reagent.His investigations on the precipitation of barium sulphatehave been prompted by the work of B0gan,~7 who claims that the particlesize of barium sulphate varies according to the age of the solution used asprecipitant.Two papers presented at a Symposium on the role of reaction rates inanalytical chemistry are of interest. O’Rourke and Johnson 78 discuss thekinetics and mechanism in the formation of slightly soluble ionic precipit-ates; they consider that precipitation occurs in two stages, involving firstnucleation and growth, and secondly only the growth of the precipitate.Barium sulphate is taken as experimental model in this study of the entireprocess of precipitation.Gordon 79 discusses slow precipitation processesfrom the standpoint of precipitation from homogeneous solution. Thismethod makes it possible to study the nature and extent of coprecipitationunder very favourable conditions. Methods for the precipitation of silverchloride from homogeneous solution have been used to study the coprecipit-ation of thallium(1) with silver chloride.80Inorganic Titrimetric AnalysisIndicato~s.-~A search of the literature failed to provide any informationon the chemical nature of “ methyl-purple,” an acid-base indicator men-tioned in last year’s Report, and recommended again this year in a titri-metric procedure for phosphorus.81 Correspondence with the manu-facturers has revealed that “ methyl-purple ” is a trade name for an aqueoussolution of methyl-red sodium salt and patent-blue dyestuff (British ColourIndex No.714) in such proportion as to give sharp colour changes in the70 M. M. Tillu and V. T. Athavale, Analyt. Chim. Acta, 1954, 11, 324.71 Sh. T. Talipov and T. I. Fedorova, Trudy Sredneaziatskogo Gosudarst. Univ. Khim.72 A. Jilek and M. KiivBnek, Chem. Zvesli, 1953, 7 , 563.73 N. Unohara, J. Chem. SOC. Japan, 1954, 76, 287.74 W. G. Cobbett and C. M. French, Discuss. Faraday SOL, 1954, 113.7 5 S. Okada and S. Magari, Analyt. Chem., 1955, 27, 1481.7 6 A. A. Benedetti-Pichler, ibid., p. 1505.7 7 E. J . Bogan, ibid., p. 1505.78 J . D. O’Rourke and R.A. Johnson, ibid., p. 1699.79 L. Gordon, ibid., p. 1704.81 I). M. Zall, E. Wagman, and N. Ingber, ibid., p. 277.Nauk, 1953, 40, 57.L. Gordon, J. I. Peterson, and B. P. Burtt, ibid., p. 1770348 ANALYTICAL CHEMISTRY.range pH 44-54. The indicator is described in a U.S. patent specific-ation.82 Nitrazine-yellow & is claimed to give a much sharper end-pointand much better results than methyl-orange in acid-base titrations, but nocomparison is made with newer mixed and screened indicators changingover the same pH range. A two-step mixed indicator containing bromo-cresol-green, New Coccine (B.C.I. No. 185), and p-nitrophenol is recommendedfor the Kjeldahl titration of ammonia in boric acid.@ The colour change isfrom blue (alkaline) through grey to yellow (acid), the grey end-point atpH 4.6 being very sharp and easily seen.The cerous-ceric redox system inthe presence of ferroin or nitroferroin can be used as a pH indicator in thetitration of weak bases; 86 the thallous-thallic system in the presence ofstarch and potassium iodide behaves similarly,86 responding to transitions ofpH around 3-2 and 8.2. The indicator can be used for the titration ofcarbonate as a mono-acid base.Acid-violet 87 (a triphenylmethane dye) and brilliant-yellow 88 arerecommended as argentimetric adsorption indicators for halides and thio-cyanate. Both are not without some of the disadvantages usually associatedwith this type of indicator. Aniline-blue and alltali-blue have also beenused as argentimetric indicator^.^^have used triphenylmethylarsonium chloride asindicator in redox titrations of highly coloured solutions. Triphenylmethyl-arsonium permanganate and dichromate are both soluble in ethylene di-chloride, forming yellow solutions, and the end-points are denoted byextraction of these substances into the organic layer.Few new indicators have been recommended for the ever-widening fieldof complexometry, despite the fact that the recent literature on titrimetricanalysis shows an overwhelming preference for complexometric methods.Gerlach 91 uses a mixture of dimethyl-yellow (or methyl-orange) and Erio-chrome Black T for titrations with E.D.T.A.; the colour change is fromgrey to wine-red.Taylor 92 recommends hzmatoxylin as indicator for thedirect complexometric determination of aluminium.This overcomes thenecessity for a back-titration procedure involving other metal solutions.Morin 93 is used as fluorescent indicator in the direct complexometnc titrationof gallium and indium. Catechol-violet is a useful indicator in complexo-metric analysis, forming coloured complexes with cations not only in alkalinebut also in acidic solution. Malat, Suk, and Ryba have developed selectiveand accurate methods for the titrations of bismuth 94 and thorium 95 usingGibson and White82 U.S.P. 2,416,619, 1947.83 W. Buss and G. Schmidt, Lebensmitt., 1954, 5, 56.84 I. H. Sher, Analyt. Chem., 1955, 27, 831.85 E. Ranke-Madsen, H. Skarbye-Nielsen, and K. Ostergaard, A d a Chem. Scand.,87 G. Muller and A.Detter, Deutsch. Apoth.-Ztg., 1954, 94, 1119.8 8 J. BognAr and J. Vereskoi, Ada Chim. Acad. Sci. Hung., 1954, 5, 91.89 N. F. Dobrovol'skii, Soobshch. Nauk Rabot. Vsesoyuz. Khim. Obshchei im Mende-O0 N. A. Gibson and R. A. White, Analyt. Chim. Acta, 1955, 12, 116, 413.O1 K. Gerlach, Angew. Chem., 1955, 67, 178.92 M. P. Taylor, Analyst, 1955, 80, 153.93 V. Patrovsky, Chem. Listy, 1953, 47, 1338.O4 V. Suk, M. Malat, and 0. Ryba, ibid., 1954, 48, 203.* 5 Idem, Coll. Czech. Chem. Comm., 1954, 19, 079.1954, 8, 1414.E. Ranke-Madsen and T. KjaergArd, ibid., 1955, 9, 293.leeva, 1953, 12BELCHER, BEVINGTON, STEPHEN, AND WEST. 349this indicator. Nickel, cobalt, manganese, zinc, magnesium, cadmium, andcopper also form coloured complexes with catechol-violet in alkaline solution,enabling these metals to be accurately determined by direct complexometrictitration.96 Flaschka and Franschitz 97 have applied the ferrocyanide-ferricyanide-3 : 3'-dimethylnaphthidine system as a general indicator incomplexometry.The method is based on an earlier procedure of Brownand Hayes.98 Musil and Theis use Chromazurol S as indicator for thedirect titration of iron, aluminium, and zirconium gs9 100~101 with E.D.T.A.Kinnunen and Merikanto lo2 have used " Zincon," as a colorimetric reagentfor zinc, in place of Eriochrome Black T as indicator in the direct titrationof zinc with E.D.T.A. and in back-titration procedures using standard zincsolutions. A similar approach may lead to the development of other selec-tive indicators for the complexometric determination of metals.Standardisation.-GAlvez Laguarta lo3 recommends using saturatedsolutions of certain substances as analytical standards where the concen-trations are accurately known from the solubility of the solute.Suitablesubstances for acidimetric and alltalimetric standards are calcium hydroxide,borax, boric acid, and tartaric acid. Pierson and Gantz lo4 prefer to usepotassium dichromate for the standardisation of titanium(@ solutions, andthey carry out the titration under carbon dioxide, using conventionalredox indicators. The titanium(II1) solution is best prepared from thehydride, which can be obtained in a very pure state.Van Hall and Stone lo5 describe the properties of 4-aminopyridine as astandard in acidimetry.There are few bases which can be used as analyticalstandards and the introduction of this base is a matter of some interest.The substance behaves as a monoprotic base, dissociation constant,1.6 x 10-5; its equivalent weight is thus 94-12 4-Aminopyridine appearsto satisfy most of the requirements for a primary standard : it is a stablecolourless solid (m. p. 161') which is easily purified by recrystallisation orsublimation and is non-hygroscopic. The reagent is readily synthesised andcan be recovered from titration residues. Used in the standardisation ofhydrochloric acid, sharp end-points are obtained with methyl-red as indi-cator. The relatively high equivalent weight is another desirable feature ofthis substance.Smith lo6 describes a convenient method for the preparation and stan-dardisation of small quantities of perchloratoceric acid solutions in per-chloric acid, thus making an important analytical reagent of very highoxidation potential readily available.The standardisation of ammoniumvanadate solutions with oxalic acid is described by West and Skoog.lo7Duval lo8 has studied the thermal stability of twelve analytical standards96 V. Suk, M. Malat, 0. Ryba, Coll. Czech. Chem, Comm., 1955, 20, 158.97 H. Flaschka and W. Franschitz, 2. analyt. Chem., 1955, 144, 421.O 8 E. G. Brown and T. J. Hayes, Analyt. Chim. Acta, 1953, 9, 6.9g A. Musil and M. Theis, 2. analyt. Chem., 1955, 144, 351.loo Idem, ibid., p. 427.lol M. Theis, ibid., p.106.lo2 J. Kinnunen and B. Merikanto, Chemist-Analyst, 1955, 44, 50.lo3 E. M. GAlvez Laguarta, I n f . Qukm. Anal., 1954, 8, 153.lo4 R. H. Pierson and E. St. C. Gantz, Analyt. Chem., 1954, 26, 1809.lo5 C. E. van Hall and K. G. Stone, ibid., 1955, 27, 1580.lo6 G. F. Smith, ibid., p. 1142.lo' D. M. West and D. A. Skoog, Analyt. Chim. Ada, 1955, 12, 301.log C. Duval, ibid., 1955, 13, 32350 ANALYTICAL CHEMISTRY.by thermogravimetry ; hydrated salts show large irregularities in watercontent, and anhydrous forms are preferred.Methods.-Numerous procedures have been recommended for titrimetricdetermination of the sulphate ion. Wilson, Pearson, and Fitzgerald 109describe improvements to the complexometric method for the determinationof 1-20 mg.amounts of sulphate; after the precipitation of barium sul-phate, the excess of standard barium chloride is titrated with E.D.T.A. Asimilar method is described by Tettweiler and Pilz 110 for the determinationof 0-01-50 mg. of sulphur in biological material; the excess of barium isreplaced by zinc on addition of a small amount of the zinc-E.D.T.A. complexand the liberated zinc ions are titrated with E.D.T.A. Belcher, Gibbons,and West ll1 apply their complexometric evaluation of barium sulphateprecipitates to the determination of sulphur in steel. Geyer 112 describesthe titration of sulphate, using a solution of barium chloride as titrant andalizarin-red S as indicator. The procedure does not differ appreciablyfrom that of Fritz and Kirkland,l13 who have made a much fuller study ofthe titration and have published a rapid titrimetric procedure for the deter-mination of macro-amounts of sulphate.A subsequent paper by Fritz andYamamura 11* deals with the titration of micro-amounts of sulphate ; thetitration is carried out in 80% ethanol, an ethanolic solution of bariumperchlorate being used as titrant and " Thorin '' [2-(2-hydroxy-3 : 6-di-sulpho-l-naphthy1azo)benzenearsonic acid] as indicator. These methodsare satisfactory only with pure sulphate solutions ; the microtitration isused for the determination of sulphate in raw and treated water after removalof cations by ion exchange.Much has been published during the year on complexometric methodsfor the determination of many metals.It is not possible to include all thepublished methods in this Report, but a critical selection of the more originalmethods is given. The literature on the analytical applications of the com-plexones is becoming confusing and some attempt must shortly be made toreview developments since Schwarzenbach's original publications on a reallycritical basis.An interesting paper 115 describes the complexometric titration ofultramicro-amounts of calcium and magnesium in 5-20 pl. of insect hzmo-lymph. Bond and Tucker 116 give three methods for the titration of calciumin the presence of magnesium. Harris and Sweet 117 determine cobalt withE.D.T.A., excess of reagent being titrated with zinc. In solutions containingonly nickel and cobalt,lls the sum of both metals is determined on onealiquot part and nickel only on another aliquot part after extraction of thecobalt as the a-nitroso-P-naphthol complex.Pribil 119 determines nickel inthe presence of cobalt by forming the E.D.T.A. complexes of both metals;lo9 H. N. Wilson, R. M. Pearson, and D. M. Fitzgerald, J . A$pl. Chem., 1954, 4, 488.110 K. Tettweiler and W. Pilz, Naturwiss., 1954, 41, 332.ll1 R. Belcher, D. Gibbons, and T. S. West, Analyst, 1955, 80, 751.112 R. Geyer, 2. analyt. Chem., 1955, 146, 174.113 J. S . Fritz and M. Q. Freeland, Analyt. Chem., 1954, 26, 1593.11* J. S . Fritz and S. S. Yamamura, ibid., 1965, 29, 1461.115 K. van Asperen and I. van Esch, Nature, 1954, 194, 927.118 R. D. Bond and B. M. Tucker, Chem. and Ind., 1954, 1236.117 W.F. Harris and T. R. Sweet, Analyt. Chem., 1954, 28, 1648.118 Idem, ibid., p. 1649.R. Pribil, Chem. Listy, 1954, 48, 825BELCHER, BEVINGTON, STEPHEN, AND WEST. 351nickel ions are then liberated by addition of potassium cyanide to thesolution. Numerous direct and indirect procedures are recommended forthe titration of aluminium.120-124 Bismuth is titrated with E.D.T.A. in thepresence of thiourea; 125 the effect of numerous ions on this titration isdescribed. An indirect procedure 126 and a method suitable for metallurgicalproducts 127 are also described for the complexometric determination ofbismuth. Other methods have been recommended for the determination ofgal1ium,l2* magnesium in the presence of aluminium,129 palladium,13* zincin aluminium alloys,131 and zirconium.132Pribil 133 has continued his studies of 1 : 2-diaminocyclohexane-NNN‘N‘-tetra-acetic acid as a titrimetric reagent; iron and manganese are titratedstepwise, and copper is determined indirectly in the presence of iron, cobalt,nickel, and manganese. Pribil has also described a modified iodometricmethod for manganese in ores and alloys, based on the titration of themanganese (111) -E . D .T. A. complex.Methods are given for the masking of iron,135 iron, aluminium, andmanganese,l36 and lead, bismuth, and other heavy metals 137 in titrationswith E.D.T.A. Collier 138 discusses the interference of phosphate in thetitration of calcium and magnesium with E.D.T.A.Among the newer and lesser-known titrants, ascorbic acid, sodiummetavanadate (vanadic acid), and chloramine-B deserve some mention.Erdey and his co-workers 139 have used ascorbic acid as a reducing titrant inthe determination of silver in alloys, plating baths, and spent “ hypo ”solutions.The neutral or slightly acid silver solution is titrated with astandard solution of ascorbic acid, Variamine Blue (4-amino-4’-methoxy-diphenylamine) being used as indicator. A procedure for the determinationof oxygen in water 140 depends on the oxidation of iron(I1) to iron(m)hydroxide, which is then dissolved in acid, and the iron(II1) titratedwith ascorbic acid. Ascorbic acid as reductant and Variamine Blue asindicator have been compared with thiosulphate and starch in severaliodometric titrations ; 141 good results are obtained in most of the titrationsexamined.120 M.Theis, 2. analyt. Chem., 1955, 144, 106.121 1. Saj6, Magyar Kern. Folybirat, 1954, 60, 268.122 Idem, ibid., 1953, 59, 319.123 H. Flaschka and H. Abdine, Mikrochim. Acla, 1955, 37.124 E. Wanninen and A. Ringborn, Analyt. Chim. Acta, 1955, 12, 308.1Z5 J. S. Fritz, Analyt. Chem., 1954, 26, 1978.1Z6 K. Lu Cheng, ibid., p. 1977.127 J. Kinnunen and B. Wennerstrand, Chemist-Analyst, 1954, 43, 88.125 G. W. C. Milner, Analyst, 1955, 80, 77.1Z9 J. A. Ritchie,,ibid., p. 402.130 W. M. MacNevin and 0. H. Kriege, Analyt. Chem., 1955, 27, 535.132 A. Musil and M. Theis, 2. analyt. Chem., 1955, 144, 427.133 R. Pribil, Coll. Czech. Chem. Comnz., 1955, 20, 162.134 R. Pribil and J.Vulterin, Chern. Listy, 1954, 48, 1132.135 H. Flaschka and R. Puschel, 2. anaZyt. Chem., 1954, 143, 330.136 R. Pribil, Chem. Listy, 1953, 47, 1333.137 R. Pribil and 2. Roubal, ibid., 1954, 48, 818.135 R. E. Collier, Chem. and I d , 1955, 587.140 L. Erdey and F. Szabadvery, ibid., p. 325.141 L. Erdey, E. Bodov, and M. Papay, ibid., 1955, 5, 235.J. C. Sergeant, Metallurgia, 1954, 50, 252.L. Erdey and L. BuzAs, Acta Chim. Acad. Sci. Hung., 1954, 4, 195352 ANALYTICAL CHEMISTRY.Singh and Sood 142 have reported further on the uses of the Chloramine-B-iodine monochloride system. In strongly acidic solution, iodide, arsenite,antimonite, mercurous chloride, stannous chloride, iron (II), hydrazine, andquinol are determined by direct titration. Indirect titrations are describedfor hydrogen peroxide, lead and manganese dioxides, and seleniumdioxide.143Vanadatometry has received considerable attention during the past yearand may prove useful in some titrimetric processes. The reduction ofvanadium(v) to vanadium(1v) proceeds smoothly and quite rapidly in mostof the recommended procedures and visual end-points with established redoxindicators are sharp. In a paper published in 1947, Willard and Manalo 1 4stated that the formal potential of the system, V0,-/V02+ is 3-1-02 v inlhl-sulphuric acid, rising to +la30 v in 8M-sulphuric acid. The high acidconcentration necessary in most vanadatometric procedures and the almostexclusive use of N-phenylanthranilic acid as indicator may thus be explained.Molybdenum is determined by reduction to molybdenum(1v) in a bismuthreductor ; 146 the reduced solution is titrated with a solution of ammoniummetavanadate, N-phenylanthranilic acid being used as indicator.Rao,Murty, and Gopala Rao 146 find that oxalic acid catalyses the indicatorreaction in the titration of uranium(1v) with vanadate solution ; diphenyl-benzidine or N-phenylanthranilic acid may be used as indicators. Hypo-phosphite and phosphite are both oxidised by an excess of vanadic acid inthe presence of silver ~u1phate.l~~ The excess of vanadic acid is titrated withstandard iron (11) and N-phenylanthranilic acid as indicator. The oxidationof thiosulphate to tetrathionate and to sulphate by vanadic acid has beenre-examined and suitable procedures for the titration of thiosulphate havebeen deve10ped.l~~ Singh and Singh titrate numerous substances directly 149and indirectly with vanadic acid in strongly acidic solutions, using iodinemonochloride as indicator.These procedures are almost identical withthose using Chloramine-B as titrant, described by Singh and So0d.1~~ Thevanadatometric determination of copper, zinc, cobalt, and mercury afterprecipitation of the metals as complex thiocyanates is described : lead iodidecan also be titrated.The direct titrimetric determination of carbon dioxide is described byBlom and Edelhausen.151 This important method involves the absorptionof the gas in pyridine or acetone and the titration of the solution withstandard sodium methoxide in methanol, thymol-blue being the indicator.The method is applied to the determination of carbon dioxide in air andin gaseous products obtained by combustion of micro- and semimicro-amounts of organic compounds.142 B.Singh and K. C . Sood, Analyt. Chim. Acta, 1954, 11, 313.143 Idem, ibid., p. 317.144 H. H. Willard and G. D. Manalo, Ind. Eng. Chem. Anal., 1947, 19, 462.145 E. V. Ankudimova, Trudy Komissii analit. Khim. Akad. Nauk S.S.S.R., Otdel.146 V. P. Rao, B. V. S. R. Murty, and G. Gopala Rao, 2. analyt. Chem., 1955, 147,147 G. Gopala Rao and H. S. Gowda. ibid., 1955, 146, 167.148 H. S. Gowda, K. B. Rao, and G. Gopala Rao, Analyt. Chim. Acta., 1955, 12, 504.140 B. Singh and S. Singh, ibid., 1954, 10, 408; 1954, 11, 412.150 Idem, ibid., 1955, 13, 405.1 5 1 L.Blom and L. Edelhausen, ibid., p. 120.khim. Nauk, 1954,5, 197.161BELCHER, BEVINGTON, STEPHEN, AND WEST. 353A simple and elegant method is described by Flaschka 152 for the titri-metric evaluation of potassium tetraphenylboron. The precipitate is dis-solved in acetone containing acetic anhydride, and the solution is titratedwith standard perchloric acid in glacial acetic acid, crystal-violet being theindicator.An interesting titrimetric procedure has been developed for the deter-mination of hypophosphite in the presence of phosphite.lm Cerium(1v)oxidises both substances quantitatively in boiling solution after 15 minutes,but at 60°, only hypophosphite is oxidised after 30 minutes. The method isaccurate and precise.w. r. s.Classical Organic AnalysisThe development of rapid methods of ultimate and functional groupanalysis has been reviewed,lM and the various methoas are compared.The effect of saving time by proper organisation of the laboratory and theuse of riderless damped balances and of calculating machines is also discussed.An alternative tube packing has been recommended for the determinationof carbon and hydrogen to avoid radio-active cross-contamination betweenconsecutive samples of 1%-labelled compounds. 155 This consists of 7 cm.of platinum gauze, 11 cm. of granular quartz (both kept at 900-950"),4 cm. of manganese dioxide mounted on platinised asbestos, and 3 cm. ofsilver-wool heated at 175".It has been found that low carbon values are obtained with certain sugarphosphates unless the boat is heated with the full blast of the flame.15sThis causes rapid deterioration of the combustion tube.If, however, thesample is covered with tungstic oxide, decomposition proceeds normally.Some glazing occurs at the junction of the tube with the long furnace becauseof attack by volatile phosphorus compounds, but this effect can be reducedby placing a boat containing tungstic oxide at this point.Wilzbach and Sykes 15' have described a procedure for the determinationof isotopic carbon in which the sample is heated with copper oxide in a sealedtube and the carbon dioxide is isolated by fractional condensation in vacuo.The results agree well with those obtained by less simple methods.The rapid high-temperature method 158 for determination of carbonand hydrogen in coal has been subjected to further examination by inde-pendent workers.'@)* It is concluded that the method is more rapid andaccurate than the Liebig method.Ammonium sulphamate has been recommended as a substitute for leaddioxide for the absorption of nitrogen oxides.161 More than 100 analysescan be carried out with one filling.It is not stated, however, if this reagent152 H. Flaschka, Chemist-Analyst, 1955, 44, 60.153 D. N. Bernhardt, Analyt. Chew., 1954, 26, 1798.15* W. Schoniger, Angew. Chern., 1955, 67, 261.155 J. D. Gabourel, M. J. Baker, and C. W. Koch, Aflalyt. Chenz., 1055, 27, 795.lS6 R. Belcher, J. E. Fildes, and A. J. Nutten, Analyt. Chiin. Acta, 1955, 13, 431.15? K.E. Wilzbach and W. Y. Sykes, Science, 1954, 120, 494.15* R. Belcher and C . E. Spooner, Fuel, 1941, 20, 130.159 R. A. Mott and H. C . Wilkinson, ibid., 1955, 34, 169.160 L. J. Edgcombe, ibid., p. 185.161 A. S . Hussey, J. H. Sorensen, and D. D. DeFord, AnaZyt. Chew., 1965, 27, 280.REP.-VOL. LII 364 ANALYTICAL CHEMISTRY.has any advantage over other alternatives to lead dioxide reviewed in thelast Report.Sources of error in the method for the direct determination of oxygenhave been investigated.162 The quartz of the combustion tube and thecarbon black must be of good quality and the temperature of the carbonmust be kept constant. A simple method of purifying carbon black isproposed.A modified method for the direct determination of oxygen has beendescribed lrn based on the Oita-Conway method.By incorporating thefillings in one tube only one furnace is required. This method appears tobe a distinct advance over the previous rather cumbersome assemblies whichhave been described.A study has been made of the reaction of copper oxide with carbondioxide in the Dumas method.lM It is claimed that a significant amountof oxygen is formed under the usual conditions of the determination and iscarried over into the azotometer. The effect is overcome by modifying boththe packing of the tube and the heating arrangements.A submicro-Kjeldahl method has been developed for amounts of nitrogenof the order of 30 pg.165 After distillation of ammonia a colorimetric methodis applied using ninhydrin as reagent.The factors influencing sealed-tube decomposition have been studiedby Kirk and his co-workers.166 When the temperature exceeds 500"ammonium hydrogen sulphate is decomposed, yielding elementary nitrogen,and also ammonia is oxidised by sulphur trioxide or oxygen.The amount ofsulphuric acid and the time of digestion may also have an influence on lossof ammonia. When a little water is added, the stability of ammonia insulphuric acid is markedly increased. Most organic compounds are decom-posed completely during 30 minutes' digestion.Baker 16' has shown that compounds which normally do not respond tosealed-tube digestion (e.g., nitro-compounds) can be analysed by mixingthem with 50 mg. of glucose or o-mercaptobenzoic acid.A digestion tem-perature of 4 2 0 4 0 " for about 45 minutes is recommended.For microgram amounts of nitrogen, Dixon 168 recommends sodiumhypobromite-sodium thiosulphate titration after digestion and distillationin the usual way, owing to the more favourable equivalent which is obtained.A new method has been described 169 in which the compound is decom-posed by heating with iodic and phosphoric acids. Nitrogen is then measuredin an azotometer. However, many types of compound, particularly hetero-cyclic compounds, yielded poor results and the general accuracy was inferiorto that of the Kjeldahl or the Dumas method.Mikl and Pech170 have extended a method developed some few yearsago for the rapid determination of chlorine, to the determination of sulphur.L.J. Moelants and W. Wesenbeck, Mikrochim. Acta, 1954, 738.163 F. H. Oliver, Analyst, 1955, 80, 593.164 T. Mitsui, Jup. Analyst, 1953, 2, 117.166 Y . Okada and H. Hanafusa, Bull. Chcm. SOC., Japan, 1954, 27, 478.166 B. W. Grunbaum, P. L. Kirk, L. G. Green, and C. W. Koch, Analyt. Chem.,lg7 P. R. W. Baker, Analyst, 1955, 80, 481.168 J. P. Dixon, Analyt. Chim. Acta, 1955, 13, 12.16@ S. Ohashi, Bull. Chem. SOC. Japan, 1955, 28, 177.170 0. Mikl and J. Pech, Chem. Listy, 1953, 47, 904.1955, 27, 384BELCHER, BEVINGTON, STEPHEN, AND WEST. 355The sample is wrapped in filter-paper which is ignited and lowered into aflask filled with oxygen, acid gases being absorbed in hydrogen peroxide.The sulphuric acid formed is titrated with standard alkali.If chlorine ispresent it is determined by titrating the neutralised solution with mercuricnitrate.A similar method has been described by Schoniger 171 for the determin-ation of chlorine and bromine, which are finally determined by the mercuricoxycyanide method.Sulphur has been determined by combustion in an empty tube withchromic oxide as ~ a t a l y s t . 1 ~ ~ Sulphur oxides are absorbed on sodiumsilicate contained in a boat which presumably is then weighed. Vecera 173claims to have improved the so-called Zinneke method by using a 10-cm.length of silver shavings kept at 450480" to absorb sulphur oxides, thesample being burnt in the usual way over a platinum contact. Silversulphate is extracted with water and titrated potentiometrically with0.01 N-pot assium iodide solution.To overcome low results due to the fixation of sulphur when metals arepresent, Sirotenko 17* recommends covering the residue in the boat after thecombustion, with boron oxide and re-igniting it.The sulphur oxidesproduced are absorbed and titrated in the usual way.A method has been described 175 for the determination of 1-100 p.p.m.of sulphur in organic liquids, in which the sample is decomposed in a verticalfurnace packed with vanadium pentoxide and the sulphur formed is measuredby a conductometric method.Chlorine in certain chlorinated aromatic compounds has been determinedby hydrolysis in a solution of potassium hydroxide in tetrahydrofurfurylalcohol.176 The alcohol is distilled off and the residual solution is titratedby Volhard's method.Brown and Musgrave 1 v 7 determine fluorine, chlorine, and nitrogensimultaneously by decomposition with sodium in a nickel bomb.Whenoxygen is absent from the compound, nitrogen is converted quantitativelyinto cyanide. Fluorine is determined on one aliquot part by means of athorium nitrate titration, chlorine on another part by argentometric titrationusing Rhodamine-BS indicator, and cyanide on a further part by the Liebig-Deniggs method. In a later paper 178 an ion-exchange method is reportedfor chlorine and fluorine after masking cyanide with formaldehyde. Thetotal acidity of the eluate is determined, and chloride then titrated argento-metrically or by the mercury oxycyanide method.Raney nickel in an alkaline medium or zinc-sulphuric acid in the presenceof palladised charcoal has been recommended as an alternative to the usualmethods of decomposition for the determination of hal0gens.17~ Theparticular reagent to be used depends on the nature of the compound.Fluorine has also been determined on the semimicro-scale after171 W.Schoniger, Mikrochim. Ada, 1955, 123.172 P. N. Fedoseev and R. M. Lagoschnaya, Zhur. analit. Khim., 1954,9,224.M. VeEefa, Chem. Listy, 1954, 48, 613.174 A. A. Sirotenko, Mikrochim. Acta, 1955, 153.175 J. A. Hudy and R. D. Mair, Analyt. Chem., 1955, 27, 802.E. H. Searle and E. Bell, J. Appl. Chem., 1954, 4, 430.177 F. Brown and W. K. R. Musgrave, Analyt. Chim. Ada, 1955, 12, 29.178 R. E. Banks, F.Cuthbertson, and W. K. R. Musgrave, ibid., 1955,13, 442.L. Simonyi, G. TokAv, and G. GBI, Magyar Kkm. Folybirat, 1954, 60, 97356 ANALYTICAL CHEMISTRY.decomposition in a Pam bomb by passing the leachings through an ion-exchange resin before titration with thorium nitrate in the usual way.lmFluorine and carbon have been determined simultaneously by decom-position in a silica tube in the presence of moist oxygen at 1100".181 Thehydrofluoric acid produced is titrated with standard alkali and the carbondioxide is determined gravimetrically after absorption in a soda-asbestostube.Burton and Riley lS2 have described a rapid method for the determin-ation of phosphorus in which the samples are decomposed in a Parr micro-bomb and then determined spectrophotometrically by the molybdenum-bluemethod.Arsenic can be determined rapidly by heating in a sealed tube for 5minutes with magnesium and magnesium oxide.lB The contents of thetube are decomposed with dilute acid and the evolved arsine is trapped in asolution of silver diethyldithiocarbamate in pyridine.The colour producedis measured spectrophotometrically . Pietsch decomposes by wetdigestion, adds barium nitrate, and determines arsenate in the filtrate bythe Volhard method. It is claimed that the method can be applied in thepresence of many metals and halogens.A modified wet oxidation method for 10-mg. samples has been developedwhich avoids the low results sometimes obtained when sulphuric-nitric acidoxidation is used.186 The sample is dissolved in sulphuric acid and oxidisedwith potassium permanganate, the excess of which is removed with hydrogenperoxide. After evaporation to fumes of sulphuric acid, the conventionaliodometric titration is applied.A new combustion procedure to determine mercury when halogens arepresent, which eliminates possible loss as mercury halide, has been de-scribed.ls6 The combustion tube is packed with calcium oxide, and mercuryis collected in a bubbler containing nitric acid.It is finally titrated withpotassium thiocyanate, ferric alum being used as indicator.Methoxyl and ethoxyl groups have been determined selectively by thetrimethylarnine method, isopropanol being used as solvent in place of theusual ethan01.1~' No solubility correction for tetramethylammonium iodideis then necessary.The latter is filtered off and ethoxyl is then determinedin the filtrate.A critical study of the methoxyl determination has been carried out.18*Erratic results were traced to the use of sodium thiosulphate in the scrubber.When 25% sodium acetate solution was used instead, satisfactory resultswere obtained. In an independent study lS9 sodium antimony1 tartrate wasfound to be the best of several scrubbing solutions which were examined.A new improved apparatus has been described by Kirsten and Ehrlich-180 C. Eger and A. Yarden, Bull. Res. Council Israel, 1954, 4, 305.181 H. E. Freier, 13. W. Nippoldt, P. B. OIsen, and D. G. Weiblen, AnaZyt. Chem.,182 J. D. Burton and J. P. Riley, AnaZyst, 1955, 80, 391.183 M.JureEek and J. Jenik, Coll. Czech. Chem. Comm., 1955, 20, 550.184 R. Pietsch, 2. analyt. Chern., 1955, 144, 353.187 G. Gran, Suensk. Papperstidning, 1954, 57, 702.188 A. E. Heron, R. H. Read, H. E. Stagg, and H. Watson, AnaZyst, 1954, 79, 671.189 R. Belcher, J. E. Fildes, and A. J. Nutten, Aszalyt. Chim. Ada, 1966, 13, 16.1955, 27, 146.G. Bahr, H. Bieling, and K. H. Thiele, 2. analyt. Chern., 1954, 143, 103.T. Sudo, D. Shimoe, and F. Miyahara, Jap. Analyst, 1955, 4, 88BELCHER, BEVINGTON', STEPHEN, AND WEST. 357Rogozinsky.lW The sample is first heated with the reaction mixture in astoppered tube for 30 minutes at 100" and is then transferred to the apparatusto distil off the methyl iodide. The determination is completed iodo-metrically.R.B.Polarography.Inorganic.-During the period covered by this Report, considerableattention has been paid to the selection of electrode systems for use inpolarographic analysis. A vibrating platinum electrode has been chosenfor the determination of oxygen in water.lgl The diffusion current varies asthe square root of the amplitude, and is greater than that obtained with arotating electrode. Platinummicro-electrodes and automatic recording have been used for polarographyin fused salts, and the effects of variation in speed of rotation, electrodearea, and temperature on the rate of polarisation have been studied.192 Anew type of mercury electrode which has a pinhole small enough to preventmercury (kept at constant pressure level) from falling has been described.193The sensitivity is comparable to that of the dropping electrode, and thepolarograms are smooth with considerably less slope than those obtainedwith the streaming electrode.Yet another form of dropping-mercurycathode, in which the end is bent into a horizontal position, has been devised.The advantage claimed is that the mercury drop has minimum size andmaximum stability. Reduction in dropping time minimises galvanometeroscillation.lM The dropping-gallium electrode has been found entirelyunsuitable. lg5 The advantages of replacing the calomel and other conven-tional reference electrodes by electrodes such as antimony, molybdenum,tungsten, graphite, etc., when the limiting current rather than the half-wavepotential is being measured, have been discussed.These electrodes simplifyvessel design, and give excellent waves.1g6 A nomogram for determiningthe characteristics of capillaries has been constructed. lS7 Japaneseauthors 198 have described a polarograph in which a small alternating currentis superimposed on the directly applied potential, and the alternatingcurrent is recorded directly on photographic paper. The method wasapplied to several analyses and theoretical implications were considered.A general discussion of the various methods of oscillographic polarographyhas been published,lg9 and its application in quantitative analysis has beentreated.200 The excellence of the Barker '' Square Wave " polarograph hasbeen demonstrated, particularly in respect to sensitivity and selectivity.mlA value of 50 C.P.S.was chosen as normal.190 W. Kirsten and S. Ehrlich-Rogozinsky, Mikrochim. Acta, 1955, 786.l*l W. Dirschel and K. Otto, Chem.-Ind.-Tech., 1954, 26, 321.IQ2 E. D. Black and T. De Vries, Analyt. Chem., 1955, 27, 906.193 Y. Yashiro, Bull. Chem. SOC. Japan, 1954, 27, 564.194 J . Smoller, Coll. Czech. Chem. Conzm., 1954, 19, 238.lS5 P. A. Gigdre and D. Lamontagne, Science, 1954, 120, 390.lQ8 L. JensovSk9, Chem.-Tech., Berlin, 1955, 7, 159.197 D. P. Schcherbov, Zauodskaya Lab., 1955, 21, 246.lS8 M. Senda, M. Okuda, and I. Tachi, Bull. Chenz. SOC. Japan, 1955, 28, 31, 37.lQ9 Ya. P. Gokhshtein and Yu. A. Surkov, Zhur. analit. Khim., 1954, 9, 319.2oo R. Kalvoda and J . Macku, Chem. Lisly, 1954, 48, 378.201 D.J. Ferrett and G. W. C. Milner, Analyst, 1955, 80, 132358 ANALYTICAL CHEMISTRY.Attention has been drawn to the non-proportionality between concentrationand maximum current in derivative polarography.a2 The effect of adsorp-tion on the anodic polarographic wave has been studiedJ203 and attention hasbeen paid to selection of the zero line in cases where an incomplete wave isobtained.204 Methods have been specified for the purification of supportingelectrolytes for use in p~larography.~~Very many analytical methods have been described during the past year.Few outstanding applications have appeared and it is only possible tomention some of the more interesting methods. The suitability of ascorbicacid, phthalic acid, and benzoic acid media for the determination of uraniumhas been examined.m6 Ascorbic acid appears to be the most efficient baseelectrolyte.rn7 Others have used an ammonium carbonate medium contain-ing ‘‘ Tiron ” (1 : 2-dihydroxybenzene-3 : 5-disulphonic acid) and com-plexone I11 (E.D.T.A.) for the same analysis.Methods for the determinationof zinc in various electrolyte media and in various alloys, ores, etc., havebeen investigated.208 The polarography of niobium has been described 204-211and also that of 213 gallium,214 indiumJ2I5 palladiumJ216and 218 The polarographic determination of copper 219 and ofcadmium and zinc 220 in cyanide solution has been investigated, and alsogeneral applications of the method to the analysis of electroplating solu-tions.221 The polarographic method is well suited to the analysis of minorconstituents in titanium alloys.222 m-Nitrophenylarsonic acid has beendescribed as a polarographic reagent for the latter After precipit-ation of the titanium compound, it is dissolved and the nitro-group ispolarographed.The polarographic behaviour of chlorides ,224 bromides,225chlorates,226 sulphate,227 sulphite,228 nitrate and nitrite,229, 230 fluoride,=l202 T. Isshiki, Y. Mashiko, and S. Tsukagoshi, Pharm. Bull., Japan, 1954, 2, 263.203 P. Zuman, Chem. Listy, 1954, 48, 1025.204 N. 2. Bruja, Rev. Chim., 1953, 4, 30.205 L. Meites, Analyt. Chem., 1955, 27, 416.208 M. V. SuSiC, Bull. Inst. Nuclear Sci. Belgrade, 1954, 4, 57, 59.207 M. V. SuSiC, I. Gal, and E. Cuker, Analyt.Chim. Acta, 1954, 11, 586.208 I. A. Korshunov, Uch. Zap. Gor’kovskogo Un-Ta, 1953, 24, 15.20s S. K. Dhar, Analyt. Chim. Acta, 1954, 11, 289.210 D. J. Ferrett and G. W. C. Milner, Nature, 1955, 175, 477.211 E. I. Krylor, U. S. Kolevatova, and V. A. Samarina, Doklady Ahad. Nauk212 A. A. Vleck, Chem. Listy, 1954, 48, 189.213 G. W. Smith and F. Nelson, J . Amer. Chem. Soc., 1954, 76, 4714.214 H. E. Zittel, Diss. Abs., 1954, 14, 1303.215 M. Bulovova, Chem. Listy, 1954, 48, 655.216 R. F. Wilson and R. C . Daniels, Analyt. Chem., 1955, 27, 904.217 J. Cihalik, J. Dolezal, V. Simon, and J. Zyka, Chem. Listy, 1954, 48, 28.218 J. Kracek, Cesk. Sklar a Keramik. 1953, 3, 183.219 J. V. Petrocelli and G. Tatoian, Plating, 1955, 42, 550.z2O T.A. Downey, ibid., p. 267.z 2 l R. Diaz, ibid., p. 415.2g2 J. J. Mikula and M. Codell, Analyt. Chem., 1955, 27, 729.2z3 E. Van Dalen and R. P. Graham, Analyt. Chim. Acta, 1955,12, 489.224 A. A. Vleck, Coll. Czech. Chem. Comm.. 1954. 19, 221.228 J. Koryta and J. Tenygl, ibid., 1954, 48, 407.227 0. A. Ohlweiler, Analyt. Chim. Acta, 1954, 17, 590.228 V. B. Aulenbach and J. L. Balmat, Analyt. Chem., 1955, 27, 562.22s R. Pletikha and E. Krzhizhova, Zhur. analit. Khim., 1954, 9, 366.Z3O Idem, Prumysl. Potravin, 1953. 4, 383.231 C. E. Shoemaker, Analyt. Chem., 1955, 27, 552.S.S.S.R., 1954, 98, 593.M. Hemala, Chem. Listy, 1953, 47, 1323BELCHER, BEVINGTON, STEPHEN, AND WEST. 359iodine and iodides 232 has been studied. Methods have been described formanganese in air,= tin in dissolved oxygen and hydrogen p e r ~ x i d e , ~ ~and for minute amounts of carbon monoxide.236Amperometric methods have been proposed for several analyses, e.g.,of ferricyanide with silver nitrate,%? of thorium with fluoride,%* of zirconiumin fluoride medium with c~pferron,%~ of calcium and fluoride (indirectlyvia calcium), and also of lead 241 with ferrocyanide, of .heavy metals withsodium hydroxide by use of a rotating platinum electrode,a2 of arsenite,ammonia, and thiocyanate with hypochlorite,243 of copper and nickel inalloy steel by means of rubeanic acid,% of copper, zinc, nickel, and cobaltwith sodium anthranilateIa5 of copper with sodium carbonate by use ofcopper electrodes (this procedure is said to be superior to the use of thedropping-mercury cathode or rotating platinum cathode) .246 Perhaps themost interesting amperometric method to be suggested during the period isthat for the determination of potassium.247 The potassium is precipitatedwith sodium tetraphenylboron, and the excess reagent is then titrated withthdous nitrate.Apart from the similar behaviour of rubidium, cxsium,and ammonium, chloride is said to interfere.Organic.-A general review of the polarographic method and instrumentsin general has been madea8 and particular attention has been paid toorganic applications of the technique.xg Studies have been made of thepolarography of steroids,2m sulphur ~ompounds,~~1 aromatic heterocyclicethers and esters.253 Many workers continue to pursue theline of functional group analysis by means of polarography and amperometrictitration.Examples are the determination of the carbonyl group,254aliphatic nitro-gro~ps,~~~ dis~lphide,~~6 ~ u l p h o n e s , ~ ~ ~ and t h i o l ~ . ~ ~ ~ Exten-sive surveys have been made of the polarography of several compounds :232 J. V. A. NovAk, Chem. Listy, 1953, 47, 903.233 I. B. Kogan and S. L. Makhover, Gigiena i Sanit., 1954, 2, 52.234 L. Bouberlova-Kosinova, Vest. Ustred Ustav. Geol., 1954, 29, 13.235 J. C. Fittipaldi, Rev. Fac. Ing. Quim. argentina, 1953, 21-22, 123.236 J. Vykoukal and K. Linhart, PaZiva, 1953, 33, 236.237 B. Khosla and H. C. Gaur, Current Sci., 1954, 23, 216.238 M. Sundaresan and M. D. Karkhanavala, ibid., p. 258.230 E.C. Olson and P. J. Elving, Analyt. Chem., 1954, 26, 1747.240 0. A. Songina, A. P. Voiloshnikova, and M. T. Kozlovskii, Izvest. Akad. Nauk241 B. Khosla, H. C. Gaur, and N. P. Ramaiah, Current Sci., 1954, 23, 361.242 J. Kamecki and M. Slabon, Roczniki Chem., 1955, 29, 107.243 H. A. Laitinen and D. E. Woerner, Analyt. Chem., 1955, 27, 215.244 Kh. Ya. Levitman and 2. A. Krivchik, Zavodskaya. Lab., 1955, 21, 397.a45 A. K. Zhdanov, R. I. Tseitlin, and A. M. Yakubov, ibid., p. 7.246 J. Kamecki and L. Suski, Roczniki Chem., 1955, 29, 115.247 W. Kemula and J. Kornacki, ibid., 1954, 28, 635.248 W. van Tongeren, Chem. Weekblad, 1954, 50, 769.249 F. Freese, ibid., p. 781.250 M. Brezina, V. Volkova, and J. Volke, Chem. Listy, 1954, 48, 194.251 P.Zuman, R. Zumanova, and J. Teisinger, Coll. Czech. Chem. Comm., 1955, 20,252 J. Volke and V. Volkova, Ckem. Listy, 1954, 48, 1031.253 M. I. Bobrova and A. N. Matregeva, Zhur. obshlhi Khim., 1954,24, 1741.264 Ch. Pr6vost and P. Souchay, Chim. analyt., 1955, 37, 3.255 R. Miquel and A. Condylis, Bull. Soc. chim. France, 1955, 236.256 J. R. Carter, Science, 1954, 120, 895.257 E. S. Levin, A. P. Shestov, Doklady Akad. Nauk S.S.S.R., 1954, 98, 999.258 M. D. Grimes, J. E. Puckett, B. J. Newby, and B. J. Heinrich, Analyt. Chem..Kazakhstan S.S.R., 1953, Ser. Khim. [6], 69.139.1955, 27, 152360 ANALYTICAL CHEMISTRY.barbituric acid derivatives,259, 260 penicillin,261 papaverine,262 chloro-p h y l l i n ~ , ~ ~ ~ cystine,264 dithiocarbamic oxalic acid,266 maleic an-h ~ d r i d e , ~ ~ ~ formaldehyde,268 aureomycin and terramycin ,26B the loweralkyl, dialkyl, and acyl peroxides,270 alkyl phthalate e s t e r ~ , ~ ~ l amaranth,272cyclohexyldini tr~phenols,~'~ diethyldithio~arbamate,~~a and di- and tri-phosphopyridine n u ~ l e o t i d e s .~ ~ ~ In addition, the polarographic assay oftechnical malathion 276 (S-1 : 2-dicarbethoxyethyl-00-dimethyl dithio-phosphate), trypsin ethyl alcohol content of bl00d,~~8 thio-compounds in blood and serum,279 and of carbon oxysulphide 280 has beendescribed. The role of polarography in biochemistry 281 and of oscillo-graphic polarographv in pharmacy has been reviewed generally.282Potentiometric Titration.-The selection of the inflection point on potentio-metric titration curves by the concentric-arcs method using a simply madetransparent template is described by Tubbs.2s The well-known abilityof a platinum electrode to respond to changes of silver-ion concentration hasbeen examined.284 The response was found to be due to a layer of silverformed at the interface and it varied with the previous treatment of theelectrode.The discussion also covers the similar behaviour of gold andcarbon electrodes. I t has been shown 285 that, in the titration of ferrousiron with ceric sulphate, a platinised platinum electrode may function partlyas an oxygen electrode when the concentration of ferrous ion is less than0.001~. A study 286 has been made of the response of a silver electrode topH, with the conclusion that it is not suitable for the determination of pHalthough a linear relationship between potential and pH was obtainedfrom pH 2 to 9.The precipitation of halides with silver nitrate has beenstudied with a glass electrode.287 The curves for direct titration againstsilver nitrate have maxima at the equivalence point and the reverse titrationZ59 P. Zuman, Chem. Listy, 1954, 48, 1006.260 Idem, ibid., p. 1020.z6l E. Krejci, Cesk. Farm., 1955, 4, 73.962 V. D. Bezuglyi, Zhuv. obshchei Khim., 1954, 24, 2190.263 W. L. Waggatzer and J. E. Christian, J . Amev. Phavna. Assoc., Sci. Ed$z., 1955,94,30.Z64 hl. Kalousek, 0. Grubner, and A.Tockstein, Coll. Czech. Ckem. Comm., 1954,19,1111.265 I<. Zahradnik and L. JenSovskv, Chem. Listy, 1954, 48, 11.246 G.F. Reynolds and R. C. Smart, Anal-yt. Chim. Acta, 1954, 11, 487.267 E. Barendrecht, Chem. Weekblad, 1954, 50, 755.Z68 L. SCrAk, Chem. Listy, 1954, 48, 272.269 0. Ti5lupilovA and V. MaSinovA, Cesk. Favm., 1953, 2, 226.270 H. Briischweiler and G. J. Minkoff, Analyt. Chim. A d a , 1955, 12, 186.271 G. C. Whitnack, J . Reinhart, and E. S t . Clair Gantz, Analyt. Chenz., 1055, 27, 359.272 G. C. McKeown and J. L. Thompson, Canad. J . Chem., 1954, 32, 1025.273 M. Maruyama and K. Maruyama, Jap. Analysl, 1964, 3, 11.274 J. Davis, A. J. Easton, and J. Freezer, Chem. and Ind., 1955, 241.275 C. Carruthers and J . Tech, Arch. Riochem. Biophys., 1955, 56, 441.276 W. H. Jura, Analyt. Chem., 1955, 27, 525.277 5 . Stokrova, Chem. Listy, 1954, 48, 1082.278 D.Monnier and W. F. Riiedi, Helv. Chim. A d a , 1955, 38, 402.279 L. Jirousek and M. Petrackova, Chenz. Listy, 1954, 48, 260.280 V. Sedivec and V. VaSAk, ihid., p. 19.281 J. de Wael, Chem. Weekblad, 1954, 50, 778.282 J . Heyrovskq, Cesk. Farm., 1953, 2, 403.283 C. I;. Tubbs, Anadvt. Chem., 1954. 26, 1670.284 I-'. L. Allen and A. Hickling, Anal.vt. Chim. Acta, 1954, 11, 467.265 T. de Vries, Chem. Weekblad, 1954, 50, 533.I-I. Khalifa and I. M. Issa, J . Indian Chem. SOC., 1954, 31, 426.287 W. Hubicki, Ann. Univ. M . Cztrie-Sklodowska, 1953, 8, 149BELCHER, BEVINGTON, STEPHEN, AND WEST. 361curves have minima. The addition of indifferent electrolytes decreases stepheight. Potentiometric titrations with controlled current input have beendescribed by Adams,28* but he has concluded that the new method is fre-quently no better than conventional potentiometry except that sometimeslarger inflexions are obtained.It has been found that a platinum electrodeimmersed in a solution containing hydrogen peroxide changes its potentiallinearly with pH.2S9 The electrode can be used for the titration of acids,bases, and certain salts and was applied to the determination of activechlorine, alkali, and carbonate in hypochlorites and chlorites. It wassubsequently used for the titration of dichromate ions and strong acidswhen present together.B0Potentiometric methods have been described for the titration of lowconcentrations of boric acid in water and deuterium oxide. The titrationwas carried out with carbonate-free potassium hydroxide with addition ofmannitol.Helium gas was used for stirring.291 Blannitol was preferred toglycerol. Other authors have confirmed that invert sugar, fructose, propane-1 : 2-diol, and ethylene glycol can also replace glycerol. These authors 298preferred ethylene glycol to mannitol. Maltose, lactose, starch, dextrin,etc., were ineffective. Quadrivalent selenium can be titrated with potassiumpermanganate in a sodium hydroxide medium.293 A new potentiometricmethod has been described for cadmium in which the latter is precipitatedas (C22H240,N4)2HB[CdBr4] by addition of diantipyrinylmethane in thepresence of a known amount of 0-%-potassium bromide. The excess ofbromide ion is then determined argent~metrically.~~~ A potential drop ofapproximately 400 mv was recorded by others for the potentiometrictitration of hydrogen peroxide with 0.1 N-potassium ferricyanide in alkalinemedium.2g5 Singh et aZ.Zg6 have continued their studies on the use ofchloramine-B by describing the potentiometric determination of ferro-cyanide, hydrazine, ferrous sulphate, iodide, arsenic(w), antimony(m),quinol, and quinhydrone.The titrations were carried out in dilute mineralacid. The potentiometric determination of sulphur in a wide variety ofmaterials has been described,2g7 and the titration of thiols and disulphidesby means of silver nitrate has been critically examined, errors in previouswork being disclosed.298 Others have described the automatic pH titrationof soluble phosphates and their mixtures.299 A mean-square error of&l*9% has been recorded for the potentiometric determination of sodiumfluoride by titration against an aluminium salt with the quinhydronee l e c t r ~ d e .~ ~ Deschamps’s method for the potentiometric titration ofa s s R. N. Adams, Analyt. Chem., 1954, 26, 1933.28g I. E. Flis, Zkur. analit. Khim., 1954, 10, 38.eeo I. E. Flis and Zh. L. Vert, ibid., p. 44.291 L. Silverman and W. Bradshaw, Analyt. Chim. Acta, 1955. 12, 177.292 J. J. Sciarra and J . A. Zapotocky, J . Amer. Pltarm. Assoc., Sci. Edn., 1955,44,370.2g3 I. M. Issa, S. A. Eid, and R. M. Issa, Analyt. Chim. Acta, 1954, 11, 275.2g4 V. P. Zhivopistsev, Uch. Zap. Molotovskogo, Gos. Un-ta, 1953, 8, 141.2B5 J. Vulterin and J .Zgka, Chem. Listy, 1954, 48, 619.2g8 B. Singh and G. Singh, Analyt. Chirn. Acta, 1954, 11, 569.2g7 G. Graus and A. Zohler, Angew. Chem., 1954, 66, 437.2B* R. Cecil and J. R. McPhee, Biochern. .J., 1955. 59, 234.2gg J. R. van Wazer, E. J. Griffith. and J. F. McCullough, Analyf. Chem., 1954,300 Sh. T. Talipov and I. L. Teodorovich, Doklady Akad. Nauk Uzbekhistan S.S.R.,26, 1755.1953, 32362 ANALYTICAL CHEMISTRY.chlorides in sea water in an aqueous acetone medium has been favourablyreviewed by Denam~r.~Ol A copper indicator electrode has been used forthe potentiometric titration of xanthates with standard copper sulphatesolution.302Conductometric Titration.-During this period relatively little workhas been done on the application of conductometric titration techniques toanalytical problems.The design of cells for precision conductometry hasbeen d i s c u s ~ e d . ~ ~ Japanese authors have reported on the conductometrictitration of copper with a O.OEiM-solution of 8-hydroxyquinoline in ethanol,=and another worker305 has determined the chloride content of serum bytitration with silver nitrate after precipitation of protein with alcohol.Higuchi et d 3 0 6 have titrated hydrochloric and sulphuric acids and theirmixtures in anhydrous acetic acid, with a standard lithium acetate reagent.The curves showed distinct breaks corresponding to C1-, SO,-, and HSO,-.The relative merits of lithium, sodium, potassium, and tripentylammoniumacetates as titrants were examined. Conductometric and potentiometrictechniques have been compared €or the titration of free acids and of acidsliberated by hydrolysis from nickel@) salts at high temperatures.307 Theconductometric titration of anabasine and lupinine mixtures in acetonesolution against 0*05~-mineral acid or naphthalene-2-sulphonic acid has beenreported. The latter titrant gave the most satisfactory results.308High-frequency Titration.The fundamentals of high-frequency titration and specifically theproperties of analysers " without electrode contact " have been discussedparticularly with reference to measurements with a heterodyne apparat~s.~O~A study has been made of the mechanism of high-frequency titrationmethods by means of a " Q meter " 310 and the relationship between the resist-ance and the concentration of the solution and its application to the explan-ation of titration curves, have been discussed in detaiL311 The same authorhas also examined the general theory of high-frequency tit ration^.^^^ Otherauthors 313 have independently examined the change in electrical character-istics of solutions during titration.Ethylenediaminetetra-acetic acid has been used as a titrant for the high-frequency determination of several cations. Hara and West 314 have usedthe Sargent Model V Oscillometer for chelation studies of several ions,301 J.Denamur, Compt. rend., 1955, 240, 1223.302 M. Oktawiec, Prace Inst. Minist. Hutnic, 1954, 5, 184.903 J. C. Nichol and R. M. Fuoss, J . Phys. Chem., 1954, 58, 696.304 K. Shinra, K.Yoshikawa, T. Kato, and Y . Nomizo, J . Chern. SOC. Japan, 1954,SO6 H. A. Teloh, Amer. J . Clin. Path., 1954, 24, 1095.306 T. Higuchi and C. R. Rehm, Analyt. Chem., 1955, 27, 408.307 F. Cuta, 2. Ksandr, and M. Hejtmhnek, Chem. Listy, 1954, 48, 1341.308 V. V. Udovenko and L. A. Vvedenskaya, Trudy Sredneaziatskogo GosudarstUniv. Khim. Nauk, 1953, 40, 3.30g K. Cruse and R. Huber, Angew. Chem., 1954, 86, 625.310 M. Honda, K. Nakano, and A. Satuka, J . Chem. SOC. Jafian, 1954, 75, 1299.311 K. Nakano, ibid., p. 773.312 Idem, ibid., p. 776.313 V. A. Zarinskii and D. I. Koshkin, Zhur. analit. Khim., 1955, 10, 110.314 R. Hara and P. W. West, Analyt. Chim. Acta, 1954, 11, 264.75, 46BELCHER, BEVINGTON, STEPHEN, AND WEST. 363particularly uranyl ion at pH 3-5-4.0,315 and bivalent metals such as nickel,cobalt, manganese, zinc, cadmium, and lead.Calcium was titrated success-fully in the presence of a phosphate buffer, but magnesium and the otheralkaline earths gave erratic results.316 Large concentrations of electrolytedisturbed these titrations. High-frequency titrations of the salts of variousorganic acids in non-aqueous solvents have been reported.317 Sodium saltswere directly titrated with perchloric acid, and potassium salts were back-titrated by using sodium acetate in glacial acetic acid.Coulometric Titrations.Coulometric determinations at constant current in unstirred solutionshave been described by Gierst et aL31* In this method only the transitiontime is measured, i.e., the interval between the establishment of capacitycharge on the electrode and the increase in potential that occurs when theconcentration of the substance at the surface of the electrode falls to zero.The subject is treated mathematically, and two transitometers are describedfor providing the necessary electrical and timing devices.Determinationsoccupy less than one minute and the accuracy is approx. 0.2%. Lingane 319has described a method and electrode assembly for the automatic coulometrictitration of acids, Another author 320 has examined the various stages inthe titration of a solution of hydrochloric acid by coulometry at constantintensity. Salicylic acid has been determined coulometrically by bromin-ation and amperometric titration of the excess generated with cuprousion.321 Electrically generated bromine has also been used for the titrationof phenols.322 Here, however, the reaction was sufficiently rapid to permitdirect determination. Selenium( rv) has been determined coulometricallywith iodide and thio~ulphate.3~ Chloride, bromide, and iodide have beentitrated coulometrically with electrically generated silver ion, dichloro-fluorescein being used as i n d i ~ a t o r .~ ~ Concentrations of lead down to10e8hil have been analysed by coulometric technique.325 Various dyes havebeen titrated coulometrically with externally generated titanous andelectrically generated permanganate 327 has been used to determine oxalate,ferrous iron, and arsenite.Photometric Titration.Underwood 328 has discussed the technique, apparatus, and applicationsThe applications are discussed in a general way of photometric titrations.s15 R.Hsra, and P. W. West, Analyt. Chim. Acta, 1955, 12, 285.316 Idem, ibid., p. 72.817 M. Ishidate and M. Masui, Pharm. Bull., Japan, 1954, 2, 50.s18 L. Gierst and P. Mechelynik, Analyt. Chim. Acla, 1955, 12, 79.320 J. Badoz-Lambling, Chim. analyt., 1954, 36, 291.321 B. Kawamura, K. Momoki, and S. Suzuki, Jap. Analyst, 1954, 3, 29.322 C. N. Van Zyl and K. A. Murray, S. African Ind. Chemist, 1954, 8, 243.s23 K. Rowley and E. H. Swift, Analyt. Chem., 1955, 27, 818.324 P. S. Tutundzic, I. Doroslovacki, and 0. Tatic, Analyt. Chim. Ada, 1955, 12, 481325 T. L. Marple and L. B. Rogers, ibid., 1954, 11, 574.826 J.S. Parsons and W. Seaman, Analyt. Chem., 1965, 27, 210.327 P. S. Tutundzic and S. Mladenovic, Analyt. Chim. Acta, 1955, 12, 390.A. L. Underwood, J. Chem. Educ., 1954, 31, 394.J. J. Lingane, ibid., 1954, 11, 2833 M ANALYTICAL CHEMISTRY.in respect of acid-base, redox, precipitation, and complexometric titrations.Stress is laid on the use of ethylenediaminetetra-acetic acid in complex-f onnation tit rat i ons. Automatic spec trophotomet ric tit rations with coulo-metrically generated titanous ion have been used for the determination ofvanadium in titanic chloride.329 Bobtelsky et al. have continued theirstudies of the heterometric technique by using quinaldic acid for the titrationof copper in the presence of sundry other and l-nitroso-%naphtholfor the determination of ferric iron and cobalt.332* 333 Other workers 334have described the automatic photometric titration of calcium and mag-nesium in carbonate rocks, using ethylenediaminetetra-acetic acid with theusual murexide and Eriochrome-black T indicators.Frame Photometry.As would be expected, during the period of the Report, the bulk ofpapers having the use of the flame photometer as their main subject matterare concerned with the analysis of small amounts of the alkali and alkaline-earth metals. A few papers deal with the determination of other ions.Thus, attention has been paid to the determination of copper in gasoline,after extraction with hydrochloric acid ; 335 to the determination of boron 336by using an aqueous methanol solvent (1 : 1) which is 0 .5 ~ in hydrochloricacid, to the determination of lanthanum 337 by use of the band spectra ofLao, and to the determination of amino-nitrogen by the ingenious device ofshaking the amino-acid solution with a suspension of copper phosphate andsubsequently determining the chelate-bound copper by the flame photo-meter .%*Vm-ous workers have reported on the determination of sodium : in puresolution,33g and in alumina in the presence of calcium 3p1 and the otheralkaline earths,342 in glass and ores,343 and in rocks.% Potassium has beendetermined : in fertilisers after ion-exchange separation 345 of interferinganions, in the presence of sodium,346* 3433 344 and in the presence of alkaline-earth metals.342 Methods have been described for lithium 342*343 and forrubidium and c ~ e s i u m . ~ ~ Methods for overcoming interference in the329 H.V. Malmstadt and C. B. Roberts, A m l y l . Chem., 1955, 27, 741.330 M. Bobtelsky and B. Graus, Analyt. Chim. Acta, 1954, 11, 253.331 M. Bobtelsky and E. Jungreis, ibid., 1955, 12, 351.333 Idem, ibid., p. 248.35a Idem, ibid., p. 263.334 L. Shapiro and W. W. Brannock, Analyt. Chem., 1955, 27, 725.as5 J. H. Jordan, Petrol Refining, 1954, 33, 158.336 J. A. Dean and C. Thompson, Anulyt. Chem., 1955, 27, 42.337 R. Ishida, J . Chem. SOG. Japan, 1955, 76, 60.338 R. E. Beauchene, A. D. Berneking, W. G. Schrenk, H. L. Mitchell, and R, E.339 F. Hegemann, V. Caimann, and H. Zoellner, Ber. deufsch. Keram. Ges., 1954, 31,340 A.Hegedas, F. K. Fukker, and M. Dvorszky, Magyar Kkm. FoZyda’rat, 1953, 59,341 F. Hegemann and B. Pfab, Glaslechn. Ber., 1954, 27, 189.342 W. Schuhknecht and H. Schinkel, 2. analyt. Chem., 1954, 143, 321.843 J. P. Williams and P. B. Adams, J . Amer. Ceram. SOC., 1954, 37, 306.344 L. Jenkins, U.S. Atomic Energy Comm., TEI-453, 1954.345 C. W. Gehrke, H. E. Affsprung, and E. L. Wood, J . Agric. Food Chem., 1955,34~1 R. Neumann, Gas Lek Ces., 1954, 93, 1229.Silker, J . Biol. Chem., 1955, 214, 731.315.334.3, 48BELCHER, BEVINGTON, STEPHEN, AND WEST. 365determination of sodium and potassium due to overIapping spectra, radi-ation, and anions have been discussed.a7 The interference of chlorohydro-carbons owing to flame quenching has been reported by Milton and Duffield.34sAnother worker 34~1 has reported on the influence of the stability of the lightsource and the mutual effects of sodium and potassium on each other.Methods have been reported for the determination of calcium in the presenceof the other alkaline earths?= in natural ~ a t e r s , ~ ~ l and in serum.352 Anacetylene flame has been used for the photometric determination of stront-ium 353 without interference from iron, sodium, calcium, and magnesiumwhen present separately.Strontium has also been determined simultane-ously with sodium, potassium, calcium, and magnesium with a multi-channelphotometer 354 and its determination in sea water 355 and in cement 356has also been reported. Flame photometry has been used for the deter-mination of trace metals in wine a57 and for the determination of inorganicsulphate358 in serum after precipitation of this anion with an excess ofbarium chloride.Absorp tiometry .Inorganic.-The development of absorptiometric methods during 1954has been re~iewed.35~ During 1955 many methods were reported in theliterature, but few of these can be regarded as outstanding contributions.Mehler 360 has reviewed potential errors in spectroyhotometry withoptically dense solutions, stressing the need for a truly monochromatic lightsource.The principles of precision colorimetry have been discussed, and ithas been shown how variations in slit width, sensitivity, and dark currentsetting affect precision. Two new photometric procedures were proposed,which offer a possible increase in precision, but require more time and effortthan normal methods.361Copper has been determined photometrically with several reagents :tetraethylthiuram disulphide which forms a yellow-brown copper complexin acid solution ; sodium di-2-hydroxyethyldithiocarbamate 362 which issaid to possess many advantages over sodium diethyldithiocarbamate ;ethylenediaminetetra-acetic acid 363 and nitrilotriacetic acid ; 364 8-hydroxy-and 8-hydro~y-2-methyl-quinoline,~~~ the latter being more suitable ;347 P.Porter and G. Wyld, Analvt. Chenz., 1955, 27, 733.348 R. F. Milton and W. D. Duffield, Chem and Ind., 1955, 280.s4Q R. Ishida, J . Chem. SOC. Japan, 1955, 76, 56.350 A. Hegedus, T. Millner, and E. Pungor, Magyar KLm.FoZy6iral, 1953, 59, 304.351 E. G. Will and B. Schwarzkopf, J . Amer. Waterworks Assoc., 1955, 47, 253.352 R. W. R. Baker, Biochem. J., 1955, 59, 566.353 A. E. Taylor and H. H. Paige, Analyt. Chem., 1955, 27, 282.s56 T. J. Chow and T. G. Thompson, Analyt. Chem., 1955, 27, 18.358 R. D. Strickland and C. M. Maloney, Amer. J . Clin. Path., 1954, 24, 1100.35Q Anon., Chemical Age, 1955, 71, 527.360 A. H. Mehler, Science, 1954, 120, 1043.361 C. N. Reilley and C. M. Crawford, Analyt. Chem., 1955, 27, 716.s62 J. E. Delaney, SanitaZk, 1954, 2, 11.a68 W. Nielsch and G. Boltz, 2. analyt. Chem., 1954, 143, 1.364 Idem, ibid., 1954, 142, 406.s65 J. Bernal-Nievas and L. Serrango Berges, Anales F k Qulm., 1954, B, 50, 459.B. L. Valee, Nature, 1954, 174, 1050.J.J. Diamond, ibid., p. 913.M. J. Pro and A. P. Mathers, J . Assoc. Ofic. Agric. Chem., 1954, 37, 945366 ANALYTICAL CHEMISTRY.guaiacol in ammonia solution; 366 hydrobromic acid (which cannot be usedin the presence of iron) ; 367 diquinolol 368, 369 and sodium diethyldithio-arba am ate.^^^^^^ Uranium has been determined by use of 1 : 3-dipentyl-propanedi-1 : 3 - 0 n e , ~ ~ ~ ammonium thi~glycollate,~~~ dibenzoylmethane(using ethyl acetate extraction), and by the thiocyanate method with 377and without 378 extraction. Iron has been determined by using variousreagents : ethylenediaminetetra-acetic acid,379, 3a0 tartaric acid 381 in thepresence of a periodate stabiliser, salicylaldehyde-glycinehydroxamicacid 382 over the pH intervals 2.35-3.34 or 5.06--10*26, phenazone-thio-cyanate, the pink complex being extracted with amyl acetate at pH 2.5,383cupferron (methanol or butane-2 : 3-dio1 being used to keep the complex ins ~ l u t i o n ) , ~ ~ dimethylglyoxime 385 but with use of pyridine rather thanammonia, with or without extraction by chlor0form,~8~ o-phenanthrol-ine,387, 388 and dipyridyl 389 and with sulphosalicylic acid 390 and variationsof the t hiocyanate meth0d.~~1-393Bismuth has been determined colorimetrically by use of thio~rea,~9~-3~~hydrobromic acid,397 sodium diethyldithio~arbamate,~~~ and phenazone-potassium iodide.399 Manganese has been determined by using sodiumdiethyldithio~arbamate,~~ the intense colour of the permanganateor that of the manganic ion following oxidation by bromate in 8N-nitricacid.m2 Ethylenediaminetetra-acetic acid 403 and dimethylglyoxime have366 M.Ya. Shapiro and V. G. Lupina, Vinodelie i Vinogradstvo S.S.S.R., 1953, 6.367 W. Nielsch and G. Boltz, 2. analyt. Chem., 1954, 142, 427.368 L. Ghyssaert, Bull. Cent. Belge Etud. Docum. Eaux, 1954, 56.369 H. Jerome and H. Schmitt, Bull. SOC. Chim. biol., 1954, 36, 1343.370 A. L. Shinkarenko, E. A. Gryaznova, and L. A. Podkolzina, Attechnoe Delo, 1954,3,21.371 H. J. Cluley, Analyst, 1954, 79, 561.373 R. H. Rush, Diss. Abs., 1954, 14, 1521.373 J. A. S. Adams and W. J. Maeck, Analyt. Chem., 1954, 26, 1635.374 L. Kosta, Sloven. Acad. Sci. Arts Ljubljana Rep., 1953, 1, 12.375 R. Piibil and M. Jelinek, Chem. Listy, 1953, 47, 1326.376 F.Will, Diss. Abs., 1954, 14, 761.377 L. Silverman and L. Moudy, Nucleonics, 1954, 12, 60.378 V. S. JovanoviC and E. F. Zucker, Bull. Inst. Nuclear Sci., Belgrade, 1954,4,111.379 W. Nielsch and G. Boltz, Mikrochim. Acta, 1954, 481.380 Y. Uzumasa and M. Nishimura, Bull. Chem. SOC. Japan, 1955, 28, 88.381 W. Nielsch and G. Boltz, Metall, 1954, 8, 374,382 A. Mukherjee, Naturwiss., 1955, 42, 127.383 E. Sudo, J . Chem. SOC. Japan, 1954, 75, 968.384 F. Buscarons and J. L. M. Malumbres, Anales Fis. Qufm., 1955, B, 51, 117.385 N. Oi, J . Chem. SOC. Japan, Pure Chem. Sect., 1954, 75, 1067.386 Idem, ibid., p. 1069.387 A. E. Harvey, jun., J. A. Smart, and E. S. Amis, Analyt. Chem., 1955, 27, 26.388 G. Nonvitz and M. Codell, Analyt. Chim. Acta, 1954, 11, 350.389 M.Schnitzer and W. A. Delong, Canad. J . Agric. Sci., 1954, 34, 324.390 L. Erdey and E. Banyai, Acta Chim. Acad. Sci. Hung., 1954, 4, 315.391 F. G. Zharovskii, Ukrain. Khim. Zhur., 1953, 19, 548.392 L. Aconsky, T. Asami, and hl. Mori, J . Amer. Waterworks Assoc., 1954, 49, 894.393 M. Gral-Cabanac, Analyt. Chim. Acta, 1955, 12, 50.394 W. Nielsch and G. Boltz, 2. analyt. Chem., 1954, 143, 13.395 N. N. Aleshkina, Sk. Stud. Nauchn Rabot Rostovskogo, Gos. Un-ta, 1953, 92.306 W. Nielsch and G. Boltz, 2. analyt. Chem., 1954, 143, 168.397 Idem, Analyt. Chim. Acta, 1954, 11, 438.398 K. L. Cheng, R. H. Bray, and S. W. Melsted, Analyt. Chem., 1955, 27, 24.399 E. Sudo, J . Chem. Sac. Japan, 1954, 75, 1291.400 E. Specker, H. Hartlramp, and M.Kuchtner, Z . analyt. Chem., 1954, 143, 425.401 A. Kozawa, M. Tanaka, and K. Sasaki, Bull. Chem. SOC. Japan, 1954, 27, 345.402 W. C. Purdy and D. N. Hume, Analyt. Chem., 1955, 27, 256.403 W. Nielsch and G. Boltz, Analyt. Chim. Acta, 1954, 11, 367BELCHER, BEVINGTON, STEPHEN, AND WEST. 367been used in the determination of nicke1,4w,405 and the former also for thatD f cobalt.N6 Other workers have used the terpyridyl,a7 nitroso-R-salt,N8and thiocyanate 409 methods. Eriochrome-black T,410 m~rexide,~ll bromo-anilic acid,% and pyrazole-blue412 have been used for the colorimetricdetermination of calcium, in addition to the alizarin413 method. Bariumhas been determined in the presence of equal amounts of calcium andstrontium by precipitation with ammonium molybdate 414 and subsequentdetermination of the molybdenum by the thiocyanate procedure.Thelatter procedure has been employed by some authors for the determinationof molybdenum itself 4 1 5 3 416 but others prefer to use the dithiol 417 procedureor the colour of the molybdoferrocyanide complex.418 Two papers havereported on the tungsten thiocyanate 420 Vanadium has beendetermined : by reduction to the quadrivalent state, reaction with ferricchloride and formation of colour of the ferrous iron thus produced withdimethylglyoxime,421 by a catalytic effect based on the enhanced oxidationof aniline in the presence of complex-forming oxalate ions,422 through theacceleration by vanadium of the oxidation of aniline by chlorates activatedwith 8-hydroxyquinoline,423 by the colour produced with catechol 424 andalso with molybdophosphate or tung~tophosphate.~~~ Ethylenediamine-tetra-acetic acid 426 and diphenylcarbazide 427 have been used as reagentsfor the absorptiometric determination of chromium.The stereotypedrhodamine-B 42*9 429 and thiourea 430 methods have been used for the deter-mination of antimony, whilst arsenic has been determined turbidimetricallyafter reduction to elementary arsenic by hypophosphorus acid 431 or by the useof silver diethyldithiocarbamate after evolution as a r ~ i n e . ~ ~ ~ Thiourea 433-436404 W. Nielsch, Z. analyt. Chern., 1954, 143, 272.405 H. Specker and H. Hartkamp, ibid., 1955, 145, 260.406 H. Goto and J. Kobayashi, J . Chem. SOC. Japan, 1954, 75, 964.407 R.R. Miller and W. W. Brandt, Analyt. Chem., 1954, 26, 1968.408 Y. Oka and M. Miyamoto, J a p . Analyst, 1953, 2, 322.409 S. Hirano and M. Suzuki, ibid., p. 316.(lo A. Young, T. R. Sweet, and B. B. Baker, Analyt. Chem., 1955, 27, 356.411 T. T. Gorsuch and A. M. Posner, Nature, 1955, 176, 268.412 L. Erdey and L. Jankovits, A c f a Chim. Acad. Sci. Hung., 1954, 4, 235.413 S. Natelson and R. Penniall, Analyt. Chem., 1955, 27, 434.414 T. Nozaki, J . Chem. SOC. Japan, 1954, 75, 168.415 Methods of Analysis Committee, B.I.S.R.A., J . Iron and Steel Inst., 1954,178, 356.418 B. Ricca and G. D’Amore, Ann. Chim. (Italy), 1955, 45, 69.420 H. Nishida, Jap. Analyst, 1954, 3, 25.421 N. Oi, J . Chem. SOC. Japan, 1954, 75, 841.422 G.Almassy and 2. Nagy, Magyar Kkm. Folydivat, 1954, 60, 118.423 V. A. Nazarenko and E. A. Birycik, Zhur. analit. Khim., 1955, 10, 28.424 V. Patrovsky, Chem. Listy, 1954, 48, 622.425 L. Erdey, K. M. Vigh, and L. Mazor, Acta Chim. Acad. Sci., Hung., 1954, 4, 259.426 R. F. Cellini and E. A. Valiente, Anales Fis. Quim., 1955, 51, B, 47.427 L. Erdey and J. Inezedy, Acta Chim. Acad. Sci. Hung., 1954, 4, 289.428 H. Onishi and E. B. Sandell, Analyt. Chim. Acta, 1954, 11, 444.42Q W. Nielsch and G. Boltz, Z. analyt. Chem., 1954, 143, 264.43O Idem, ibid., p. 81.431 S. Hirano and D. Ishii, Jap. Arzalyst, 1953, 2, 28.432 M. JureEek and J. Jenik, Coll. Czech. Chem. Comm., 1955, 20, 550.433 A. Jilek and J. Vrestal, Chem. Zvesti, 1953, 7, 33.434 W. Nielsch, Z.anal-vt. Chem., 1955, 144, 191.435 W. Nielsch and G. Boltz, 2. Metallkunde, 1954, 45, 380.436 W. Nielsch and L. Giefer, 2. analyt. Chem., 1955, 145, 347.K. Protiva, Chem. Listy, 1954, 48, 779.C. H. Williams, J . Sci. Food Agric., 1955, 6, 104.Methods of Analysis Committee, B.I.S.R.A., J . Iron and Steel Inst., 1954,178, 356368 ANALYTICAL CHEMISTRY.has been used extensively in the absorptiometric determination oftellurium, and phosphorous acid has been employed to reduce it to metallictellurium before measurement of the absorption in the ultraviolet region.3 : 3'-Diarninobenzidine yields an intense yellow piazselenol with selenitesolutions; this has been used in the determination of selenium.&* Thestructure of the alumjnium-morin complex has been examined, and what isclaimed to be a new method has been proposed on this ba~is.43~ In thealuminon method, precipitation of the aluminium lake has been preventedby formation of the aluminon-aluminium-sulphosalicylic acid complex.440Others 841 prefer Eriochrome-cyanine to aluminon.Ferroin 442 and thefluorescence of alurninium-8- hydrox yquinoline 443 under carefully controlledconditions have also been employed in absorptiometric methods for alu-minium. Various reagents have been used in the absorptiornetric deter-mination of titanium : salicylhydroxamic acid * (yellow coloiir in diluteacid solution), " Tiron " in the presence of E.D.T.A.,446 sulphosalicyljc acid,446hydrogen p e r o ~ i d e , ~ ' ~ and t h i o ~ y a n a t e . ~ ~ Many authors report onvariations of the silicomolybdate procedure for the determination of silicatein various 8-Hydroxyquinoline has been used for thedirect colorimetric determination of magnesium 457 and also indirectlyafter treatment with sulphanilic acid and sodium 459 Titan-yellow 460 and Eriochrome blue-black B 461 have also been used as colori-metric reagents for determination of the same metal.The variables in thethiourea method for tin have been closely examined.462 The tetrabromo-chrysazin463 and dianthrimide464 methods for boron have been re-investigated.437 R. A. Johnson and B. R. Andersen, Analyt. Chem., 1955, 27, 120.438 J. Hoste and J. Gillis, AnaZyt. Chim. Acta, 1955, 12, 158.4313 2. G. Szabo and M. T. Beck, Acta Chim. Acad.Sci. Hung., 1954, 4, 211.440 D. Eckerdt, L. Hartinger, and L. Holleck, Angew. Chem., 1955, 67, 178.441 K. Wacykiewicz, Prace Inst. Minist. Hutnic, 1955, 7 , 35.442 M. Delevaux, R. Smith, and F. S . Grimaldi, U.S. Atomic Energy Comm., TE1-450,443 J. W. ColIat and L. B. Rogers, AnaZyt. Chem., 1955, 27, 961.444 J. Xavier, A. K. Chakraburtty, and P. Ray, Science and Cztltuve, 1954, 20, 146.4d5 P. Szarvas and B. Csiszar, Magyar Kbm. Folybirat, 1955, 6l, 50.4413 K. Saarni and S. Suikkanen, 2. analyt. Chem., 1954, 143, 112.447 J. R. Simmler, K. H. Roberts, and S . M. Tuthill, Analyt. Chew., 1954, 26, 1902.448 G. AlmfLssy and P. Szarvas, Magyar Tud. Akad. Kbm. Tztd. Oszt Kozl., 1953,449 C. E. Crouthamel, B. E. Hjette, and C. E. Johnson, Analyt. Chern., 1955,450 Glasgow Absorptiometry Panel, MetaZZurgia, 1954, 50, 145.451 B.E. Remik, G. P. Fedorova, and G. N. Veritennikova, Nauk Zapisk. Denepr.452 P. Enghag, Jernkontorets Ann., 1954, 138, 404.453 J. Celechovskjl, Chem. Listy, 1954, 48, 391.454 J. B. Mullin and J. P. Riley, Analyt. Chi?%. Acfa, 1955, 12, 162.455 H. Wolk, Arch. Eisenhiittenw., 1954, 25, 333.456 M. Jean, Chim. analyt., 1955, 37, 125.457 C. L. Luke and M. E. Campbell, Analyt. Chem., 1954, 26, 1778.458 N. Yokouchi, J a p . Analyst, 1954, 3, 3.459 M. Suzuki, ibid., p. 93.460 H. J. G. Challis and D. F. Wood, Awlyst, 1954, 79, 762.4 a W. Nielsch and G. Boltz, 2. analyt. Chem., 1954, 143, 161.463 J. H. Yoe and R. L. Grob, Analyt. Chem., 1954, 26, 1466.464 H. Baron, 2. anaZyt.Ckem., 1954, 143, 339.1954.3, 413.27, 507.Gos. Univ., 1953, 43, 79.V. A. Nazarenko and E. A. Biryuk, Zavodskaya Lab., 1955, 21, 20BELCHER, BEVINGTON, STEPHEN, AND WEST. 369Dithizone methods for 466 zinc,467 and mercury 469have been employed. Carmine-red 38 and quinalizarin 470 have been usedfor thorium , and 9-phenetidine 471 and starch-iodine 472 (oxidation ofpotassium iodide) for thallium. Hydrogen peroxide,473 8-hydroxyquinol-ine,474 and thiocyanate-acetone methods 475 have been used to determineniobium, and in the last case, tantalum was determined simultaneously by amodified pyrogallol procedure.Cerium has been determined absorptiometrically with ~eratrole,'?~germanium with diphenyl~arbazone,4~~ gallium with rh0damine-B,4~8zirconium with ali~arin-S,*~~ beryllium by a new method with Solochromebrilliant-blue,32 phosphorus by the molybdenum-blue method using ascorbicacid as r e d u ~ t a n t , ~ ~ sodium by direct colorimetry with violuric acid inanhydrous dimethylformamide 481 and indirectly via uranyl thiocyanatefollowing precipitation of sodium zinc uranyl acetate in the usual ~ a y , * 8 ~the rare earths by aluminon 483 and alizarin-red S,4M platinum by p-nitroso-dimethylaniline,485 and palladium by the same reagent or with ethylene-diaminetetra-acetic fi-nitr~so-cr-naphthol,~~~ or thiourea.48*Hydrogen peroxide has been determined by addition of ferrous iron andt h i ~ c y a n a t e , ~ ~ ~ and carbonyl sulphide by hydrolysis to sulphide and deter-mination by the methylene-blue rneth~d.~~O Atmospheric sulphur di-oxide 491 has been determined by catalytic reduction to hydrogen sulphideand reaction of the latter with ammonium molybdate, and sulphate492has been determined following conversion into sulphuric acid on a cationexchanger by treatment with lanthanum and a measured amount of solidthorium borate-amaranth reagent (the released dye is measured at 621 mp).Nitrogen has been determined in steel by the ammonia-pyrazolone-pyridinemethod:% and in organic compounds following Kjeldahl digestion by reaction465 L.Erdey, G. Y . RCidy, and V. Fclps, Acta Chim. Acad. Sci. Hung., 1954, 5, 133.466 M. Shima, Jap. Analyst, 1953, 2, 96.467 T. Kato and S. Takei, ibid., p. 208.468 A. Petzold and I. Lange, 2. analyt. Chein., 1955, 146, 1.46s A.C. Rolfe, F. R. Russel, and N. T. Wilkinson, Analyst, 1955, 80, 523.470 A. Purushottam, Z . analyt. Chem., 1955, 148, 245.4 7 1 S. Iijima and Y . Kamemoto, J . Chem. SOC. Japan, 1954, 75, 1294.472 V. S. Fikhengol'ts and N. P. Kozlova, Zavodskaya Lab., 1955, 21, 407.473 R. Pickup, Colon. Geol. Min. Resources, 1955, 5, 174.474 J. L. Kassner, A. G. Paratla, and E. L. Grove, Analyt. Chem., 1955, 27, 492.475 A. E. 0. Marzys, AncaZyst, 1955, 80. 194.476 H. N. Antoniades, Chemist-Analyst, 1955, 44, 34.4 7 7 G. S . Desmuk, Zhur. analit. Khim., 1955, 10, 61.478 H. Onishi, Analyt. Chem., 1955, 27, 832.478 E. C. Mills and S. E. Herman, Mefallurgza, 1955, 51, 157.480 L. Erdey, V. Felps, and E. Bodor, Acta Chim Acad.Sci. Hung., 3954, 5, 65.4 8 1 R. F. Muraca and J. P. Bonsack, Chemist-Analyst, 1955, 44, 38.482 P: N. Kovalenko and V. V. Tenkovtsev, Uhrain. khim. Zhur., 1954, 20, 411.483 L. Holleck, D. Eckardt, and L. Hartinger, 2. analyt. Chem., 1955, 146, 103.484 R. W. Rinehart, Analyt. Chem., 1954, 26, 1820.485 J. J. Kirkland. Diss. Abs., 1954, 14, 760.486 W. M. MacNevin and 0. H. Kriege, Analyb. Chem., 1954, 26, 1768.487 K. L. Cheng, ibid., p. 1894.488 W. Nielsch, Mikrochim. Acta, 1954, 532.489 F. Patty and P. B. Maury, Compt. vend., 1954, 289, 976.494 L. A. Pnrsglove and H. W. Wainwright, Analyt. Chenz., 1954, 26, 1835.481 H. Stratmann, Mikrochem. Acta, 1954, 668.492 J. L. Lambert, S . K. Yasuda, and M. P. Grotheer, Analyt. Chem., 1955, 27, 800.499 J.B. Lear, Diss. Abs., 1954, 14, 1520370 ANALYTICAL CHEMISTRY.with phenol and hypochlorite in the presence of a nitroprusside catalyst.494Nitrite has been determined by reaction with thioglycollic acid and extrac-tion with diisopropyl ether-pentanol-a~etone.~~~Chloride has been determined by reaction with silver iodate and liber-ation of iodine from the displaced iodate ion by treatment with acid andcadmium iodide-starch reagent .496 The liberation of red Chromotrope-2Bfrom the blue thorium lake by the fluoride ion has been used as a means ofdetermining the latter.497 It has also been determined after distillation offluorosilicic acid by the bleaching of the thorium-alizarin lake.49* Pyro-phosphate has been determined by the cysteine-catalysed reaction withFiske’s molybdate reagent .499 Hypophosphite has been determined byreaction with molybdic acid.500T.S. W.Radiochemical Methods of Analysis.Radiochemical analysis was very briefly reviewed in Annual Reportsfor 1953,501 but the importance of isotopic methods is now such that a specialsection is devoted to them. Radioactive and enriched stable isotopes arenow generally available 502 and there are facilities for irradiating materialsin high fluxes of thermal neutrons; 502 many laboratories are equipped toundertake isotopic work. Unless special problems are being studied, theassay of radioactive isotopes requires only apparatus which is available com-mercially; a list of equipment manufactured in Great Britain has beenpublished..503 The total cost of fitting a laboratory for simple radiochemicalwork compares favourably with the initial costs for other modern instru-mental methods.For work with stable isotopes, a mass spectrometer isgenerally needed ; commercial instruments are of necessity expensive butof course can be used for analytical purposes besides those involving isotopes.There are now many useful text-books dealing with isotopic methods inChemistry; there has been a series of ten articles dealing with all aspectsof work with radioactive isotopes. The Atomic Energy Authority of GreatBritain has a school in which instruction in the uses of isotopes is given.Two conferences, in 1951 and 1954, on the uses of radioactive isotopeshave been organised by the Atomic Energy Research Establishment andheld at Oxford.At both conferences, there was a very wide range ofsubjects since the only feature common to all the papers presented was theuse of radioactive isotopes. The papers and the discussions on them have494 B. Lubochinsky and J. P. Zalta, Bull. SOC. Chim. biol., 1954, 36, 1363.495 M. Ziegler and 0. Glemser. 2. analyt. Chem., 1956, 144, 187.498 J . L. Lambert and S. K. Yasuda, Analyt. Chem., 1955, 27, 444.497 H. F. Liddell, Analyst, 1954, 79, 752.498 L. Bloch, Ckem. Weekblad, 1955, 51, 65.499 R. M. Flynn, M. E. Jones, and F. Lipmann, J . Biol. Chem., 1954, 211, 791.500 G. Gutzeit, U.S.P. 2,697,651, 1954.501 C. L. Wilson, Ann. Re$orts, 1953, 50, 375.502 “ Radio-active Materials and Stable Isotopes,” Atomic Energy Research Estab-lishment, Harwell, 1954.503 “ Radio Isotope Instrumentation and Accessories,” edited by D.Taylor andA. G. Peacock, Scientific Instrument Manufacturers’ Association of Great Britain,London, 1955.604 F. P. W. Winteringham, Lab. Practice, 1955, 4, 94, 148, 196, 244, 288, 328, 370;411, 449, 493BELCHER, BEVINGTON, STEPHEN, AND WEST. 37 1been In the summer of 1955, a large conference on thepeaceful uses of atomic energy was held at Geneva. A meeting at Edinburghon the use of radioactive materials in biological assays has been r e p ~ r t e d . ~ ~It is evident that workers in the medical and biochemical fields have beenreadier to apply isotopic methods than workers in the physical fields, butthe methods are now being used in investigations of many types, e.g., inresearch in the paint industry.510 An indication of the wide application ofthese methods is the fact that titles of papers now do not always indicatethat isotopic methods have been used in the work described.The most significant point in connection with the use of radioactiveisotopes in analysis is the great sensitivity of detection; depending uponthe isotope being studied, the limit of detection is between 10-l1 and g511Other important features of certain isotopic methods in analysis is theirspecificity, and the fact that the decay of a radioactive isotope is independentof its chemical and physical state.Almost all the chemical applications of radioactive isotopes are analyticalin nature.The topics discussed and the references cited in this Report havebeen selected to show the wide range of problems which can be tackled byisotopic methods; it has been necessary to choose those topics in which theanalytical aspects of the work are stressed.Isotopes as Accessories in Analysis.-The use of radioactive isotopes todetermine the solubilities of sparingly soluble materials is well known; 512labelled materials can also be used to study distribution equilibria, co-precipit -ation , adsorption, and other phenomenaof importance in analytical procedures.Efficiencies of separation can be assessed by labelling one of the com-ponents of a mixture and measuring activities during the course of theseparation ; the measurements can be rapid, non-destructive, and verysensitive.Radioactive isotopes have been used to test the separation byliquid-liquid extraction of the following pairs of elements : niobium andtantalurnJ5l3 cobalt and zincJ514 and protactinium and niobium.515 Thecontrolled-potential electro-separation of copper, bismuth, and lead hasbeen tested 516 with radioactive isotopes. Isotopic methods have beenemployed 517 in a study of the purification of metals by zone melting. Theseparation of tin, antimony, and tellurium with anion-exchange resins,518and paper chromatographic methods for separating inorganic ions 519 and605 “ Radio Isotope Techniques, Vol. I, Medical and Physiological Applications,”H.M.S.O., London, 1953.GO6 “ Radio Isotope Techniques, Vol. 11, Industrial and Allied Research Applic-ations,” H.M.S.O., London, 1952.“ Radio Isotope Conference, 1954, Vol.I, Medical and Physiological Applic-ations,” Butterworths, London, 1954.508 “ Radio Isotope Conference, 1954, Vol. 11, Physical Sciences and IndustriaApplications,” Butterworths, London, 1954.509 R. F. Glascock, Nature. 1955, 176, 427.510 D. F. Rushman, J . Oil Colour Chemists’ Assoc., 1953, 36, 352.511 H. Seligman, ref. 506, p. 1.512 H. K. Zimmerman, Chem. Rev., 1952, 51, 26.613 J. Y . Ellenburg, G. W. Leddicotte, and F. L. Moore, Analyt. Chem., 1954, 26, 1045.514 H. A. Mahlman, G. W. Leddicotte, and F. L. Moore, ibid., p. 1939.515 F. L. Moore, ibid., 1955, 27, 70.516 M. Ishibashi, T. Fujinaga, and Y . Kusaka, J . Chem. SOC. Japan, 1954, 75, 13.517 P.Albert, F. Montariol, R. Reich, and G. Chaudron, ref. 508, p. 75.518 G. W. Smith and S. A. Reynolds, Analyt. Chirn. Acta, 1965, 12, 151.519 M. Lederer, ibid., p. 146372 ANALYTICAL CHEMISTRY.uranium from many metals 520 have been studied with radioactive isotopes.It has been shown 521 by labelling with 35S that cyclohexyl methyl sulphidecan be completely separated from the corresponding sulphoxide by chromato-graphy. Radioactive metallic tracers (in the form of salts) have been addedto petroleums before ashing to see if the metals are completely retained inthe ash.522Isotopic methods have been used 523 to test precipitations in the colori-metric determinations of niobium and tantalum in steels. Procedures forthe micro-determination of beryllium have been tested 524 with 7Be.Methods for precipitating germanium have been examined 525 with ?lGe.Radioactive isotopes have been used 526 in critical studies of methods fordetecting and separating potassium, rubidium, and casium.In very accurate absorptiometric determinations of niobium inminerals 527 and steels,528 addition of 95Nb at an early stage in the deter-mination allows one to make corrections for small losses of the elementduring chemical separations.Isotopic methods have been combined withflame photometry to determine strontium in sea water,529 and with X-rayspectrographic methods in analyses for uranium and thorium.6306OCo has been used 531 for testing the various stages in the assay ofvitamin B12. Evaluations of determinations of iodine in biological materialshave been carried out 5329 533 with 1311.The removal from high polymers ofmaterials of low molecular weight, e.g., unused initiator, present at very lowconcentrations has been tested 534 with labelled materials. Efficiencies offractionations of high polymers can readily be assessed 635 by using mixturesof unlabelled and labelled polymers.Isotope Dilution Analysis.-A well-known and important application ofradioactive isotopes and enriched stable isotopes is in the method of isotopedilution analysis.m6 This method is applied to the analysis of complexmixtures ; it is essential that pure samples of the various components shouldbe recovered from the mixture but the necessity for complete recovery isavoided.The calculations, when using radioactive labels, are simple ; withstable labels the calculations are slightly more complicated because theconcentration of the labelling atoms needs to be such that the molecularweight of the substance is affected.In one method of working, the components of the mixture are unlabelled620 H. P. Raaen and P. F. Thomason, Analyt. Chem., 1955, 27, 936.521 G. Ayrey, D. Barnard, and C. G. Moore, J., 1953, 3179,682 L. 0. Morgan and S . E. Turner, Analyt. Chem., 1951, 23, 978.523 T. F. Boyd and &I. Galan, ibid., 1953, 25, 1568.624 T. Y. Toribara and R. E. Sherman, ibid., p . 1594.525 L. K. Bradacs, 1.-M. Ladenbauer, and F. Hecht, Mikrochirn. Acta, 1953, 229.526 W. Geilmann and W . Gebauhr, 2. analyt.Chem., 1954, 142, 241.527 G. W. C . Milner and A. A. Smales, Alaalyst, 1954, 79, 315.528 Idem, ibid., p . 425.529 A. A. Smales, ibid., 1951, 'SS, 348.530 W. J. Campbell and H. F. Carl, Analyt. Chem., 1955, 27, 1884.531 F. A. Bacher, A. E. Boley, and C. E. Shonk, ibid., 1954, 28, 1146.632 J. W. Decker and H . S. Hayden, ibid., 1951, 23, 798.533 H. Spitzy, Mikrochim. Acta, 1955, 130.534 J . C. Bevington, H. W. Melville, and R. P. Taylor, J . Polymer Sck., 1954, 12, 449.535 J. C. Bevington, G. M. Guzman, and H. W. Melville, Proc. Roy. SOC., 1954, A ,636 See, e.g., M. D. Kamen, " Radio Active Tracers in Biology," 2nd Edition, Academic221, 437.Press, New York, 1951BELCHER, BEVINGTON, STEPHEN, AND WEST. 373and it is necessary to prepare pure labelled samples of the components forwhich analyses are required.This method is likely to be encountered inanalyses of commercial and natural products. Recent applications includeanalyses for substances of biological and biochemical interest, e.p., per+illi ins,^^^, 538s 539 vitamin B,,,5Qo, 531 vitamin D,=l2 : 4dichlorophenoxyacetieacid,M2 y-hexachlor~cycZohexane,~~~ D- and L-glutamic acid,6Q5 ~ - g l u c o s e , ~ ~gentiobiose,5Q6 and t h y r o ~ i n e . ~ ~ Other examples of isotope dilution ana-lysis are the determinations of diethyl ether in mixtures of acrylic acidand ethanol,5q8 triphosphates and pyrophosphates in mixtures,M9 ~ i n c , ~ l % 550lead,551 niobium in mixed oxides of niobium, tantalum, and titanium,552water in s o l i d ~ , ~ u and free sulphur in vulcanised rubber.55qAnother method of working can be applied in research problems requiringthe determination of the various products of a reaction; the products maybe present in very small quantities.The reaction is performed with labelledreactants so that the products are labelled; unlabelled carriers are added.Purity of the isolated samples is extremely important since contaminationby traces of a labelled impurity may seriously affect the results; the onlyconclusive test for efficiency of purification is to perform trials on a mixtureof an unlabelled sample of the substance with labelled samples of all possiblecontaminants. Isotope dilution analysis of this type has recently beenapplied 555 to reactions involving substances of importance in radicalpolymerisations, e.g., initiators, retarders, and inhibitors.Isotope dilution analysis has been used by Grosse, Kirshenbaum, andtheir co-workers for the determination of oxygen in many compo~nds.6~*Molecular oxygen enriched in l80 is added to the material and the conditionsare adjusted so that there is complete exchange between the elementaryoxygen and the oxygen in the specimen; comparison of the l 8 0 contentsof the original oxygen and the equilibriated mixture allows calculation ofthe oxygen content of the specimen.In copper, oxygen contents between0.01 and 0.1% by weight can be determined.557 The method can also beused for other elements.As a result of the development of mass-spectrometric techniques forsolids and the availability of enriched isotopes for many elements, isotope637 J.T. Craig, J. B. Tindall, and M. Senkus, Analyt. Chcm., 1951, 23, 332.538 hI. Gordon, A. J . Virgona, and P. Numerof, ibid., 1954, 26, 1208.538 G. C. Ashton and M. C. Foster, Analyst, 1955, 80, 123.5p0 E. L. Smith, ref. 505, p. 281.5u1 P. Numerof, H. L. Sassaman, A. Rodgers, and A. E. Schaefer, J . Nutrition,6.2 P. Sarensen, Analyt. Chem., 1954, 28, 1581.543 J. T. Craig, 1'. 1;. Tryon, and LV. G. Brown, ibid., 1953, 25, 1661.544 R. Hill, A. G. Jones, and D. E. Palin, Chem. and Ind., 1964, 162.545 C. C. Barker, I. W. Hughes, and G. T. Young, J., 1951, 3047; 1962, 1574.54% J. C. Sowden and A. S. Sprigs, J . Amer. Chem. SOC., 1954, 76, 3539.547 E. P. Reineke, J .Daivy Sci., 1954, 37, 1227.J. G. Burtle and J. P. Ryan, Analyt. Chem., 1955, 27, 1215.548 0. T. Quimby, A. J. Mabis, and €3. W. Lampe, &id., 1954, 26, 661.550 K. Theurer and T. R. Sweet, ibid., 1953, 25, 119.551 €3. von Buttlar, Natuvwiss., 1955, 42, 90.5 5 2 J. Reydon and C. Fisher, AnaZyt. Chim. Acta, 1953, 8, 538.553 R. Viallard and Marchetti, Chinz. analyt., 1954, 36, 214.s54 S. Ikeda and S. Kanbara, J . Chem. SOC. Japan, 1954, 75, 1308.555 J. C. Eevington and H. W. Melville, ref. 508, p. 3.5 5 % See, e.g., A. D. Kirshenbaum and A. G. Streng, Analyt. Chem., 1953, 25, 638.557 A. D. Kirshenbaum and A. V. Grosse, ibid., 1954, 26, 1955.1955, 55, 13374 ANALYTICAL CHEMISTRY.dilution analysis can be applied to many solids. Thorium has been deter-mined 558 in this way.Rocks have been dated 559 by determining the ratioof radioactive s7Rb to stable s7Sr. The use of the technique for traceimpurities in solids has been discussed ; 560 in many cases impurities at 10-10%by weight can be detected.The principle of isotope dilution is applied also in other analyticalprocedures involving isotopes.Labelled Reagents-In a number of cases an element or compound canbe determined by reaction with a labelled reagent; the activity of a pre-cipitate or a derivative can then be used to calculate the quantity of theelement or compound in the sample. The method is capable of greatsensitivity but it requires complete recovery of the pure derivative ; thisdifficulty can be overcome in some cases by a double tracer t e ~ h n i q u e .~ ~ l ~ 562[131I]~-Iodobenzenesulphonyl chloride (" pipsyl chloride ") has beenused as a reagent for amino-acids; 563 it is suitable for any amine whichgives a crystalline pipsyl derivative. This reagent has been used -in analysesfor histamine 564 and pyrimidines,565 and the double labelling technique hasbeen u ~ e d . ~ ~ 1 ~ 562 Acetic anhydride labelled with 3H and 14C has been usedas a reagent for hydroxy- and arnino-compound~.~~~ Compounds of thesetypes have also been determined with 3-chloro-4-methoxybenzoyl chloridelabelled with 36Cl at the 3 - p o ~ i t i o n . ~ ~ ~ Amino-acids on paper chromato-grams have been located with methyl [1311]iodide followed by scanning ofthe paper for activity; 568 the reagent caused some methylation of thecellulose and a consequent increase in background.The positions of fattyacids on paper chromatograms may be fixed by converting the acids intotheir cobalt salts by use of s°C0.510The identification and estimation of the free radicals in reaction mixturescan be performed 569 by adding radioactive iodine to the system. The smallamounts of the corresponding labelled iodides can then be determined byisotope dilution analysis.Potassium has been determined with reagents labelled with 60Co.570-572The same isotope has been used in reagents for the determination of thall-ium 573 and antimony.574 [lloAg]Silver nitrate has been used 575 in the558 G. R. Tilton, L. T. Aldrich, and M. G. Inghram, Analyb.Chem., 1954, 26, 894.559 R. H. Tomlinson and A. K. Das Gupta, Canad. J . Chem., 1953, 31, 909.560 G. P. Barnard, Analyst, 1954, 79, 594.5 6 1 A. S. Keston and J. Lospalluto, Fed. Proc., 1951, 10, 207.662 A. S. Keston, S. Undenfriend, and M. Levy, J. Amer. Chem. Soc., 1947, 69,563 A. S. Keston, S. Undenfriend, and R. K. Cannan, ibid., 1946, 68, 1390; 1949,564 R. W. Schayer, Y. Kobayashi, and R. L. Smiley, J . Biol. Chem., 1955, 212, 593.565 J. R. Fresco and R. C. Warner, ibid., 1955, 215, 751.566 P. Avivi, S. A. Simpson, J. F. Tait, and J. K. Whitehead, ref. 607, p. 313.567 P. Serrensen, Analyt. Chem., 1955, 27, 388.568 F. P. W. Winteringham, A. Harrison, and R. G. Bridges, ref. 505, p. 352.569 G. R. Martin, ref. 506, p. 115.570 E. Sanchez Serrano and I.Lopez Santos, BoZ. radiactividad, 1951, 24, 49.5 7 1 T. Ishimori and Y . Takashima, Bull. Chem. SOC. Japan, 1953, 26, 481.572 I. M. Korenman, F. R. Sheyanova, and 2. I. Glazunova, Zuvodskaya Lab.,579 T. Ishimori, Bull. Chem. SOC. Japan, 1953, 28, 336.574 T. Ishimori and K. Ueno, ibid., 1955, 28, 200.575 C. Barcia Goyanes, E. Sanchez Serrano, and C. Gamis, Bol. radiactividad, 1954,3151; 1950, 72, 748.71, 249.1955, 21, 774.26, 37BELCHER, BEVINGTON, STEPHEN, AND WEST. 3'1 t)formation of Ag,TIPO, and Ag,TlAsO, and the determination of phosphatesand arsenates. Quantitative paper chromatography with traces of metalions has been achieved with the aid of hydrogen ~5S]s~lphide.67s Thesmall amounts of silver in photographic images have been determined 577by converting the silver into silver [131I]iodide ; the method could be adaptedfor the determination of small amounts of silver chloride, bromide, orsulphide. This procedure is similar to one proposed 578 earlier, viz., theconversion of the silver into cobalt ferrocyanide by means of 6oCo.Activation Analysis.-Neutron activation analysis is a powerful methodfor elementary analysis particularly suited for the determination of tracequantities; 579 with certain limitations, it is independent of the chemicalnature of the material. The method depends upon the fact that the atomsof many elements are converted into radioactive isotopes by reactions withslow neutrons ; other bombarding particles---particles, protons, anddeuterons-can be used for activation, but activation by neutrons is generallyfavoured.5rnThe method was described in Annaal Reports of 1949; 581 reviewspublished since 1949 include those by Smales 5rn and Meinke.b882 Usuallythe very high fluxes of thermal neutrons available in nuclear reactors areused, but small neutron sources, e.g., a 25-mg. radium-beryllium source, canbe used successfully in many cases; 583 sources of this kind can be installedin almost any laboratory.Usually it is necessary to add carriers to the irradiated samples and then,following the procedure of isotope dilution analysis, to isolate pure specimensand determine their activities.Recent developments have simplified thechemical manipulations. The activities due to the various isotopes in amixture can be measured by using filters chosen so that they absorb theradiations emitted by certain of the isotopes.The filter technique is notgenerally applicable and results in some loss of sensitivity. y-Spectrometrycan be used for detecting and estimating y-emitters in mixture~,~84-58~provided that the energies of the y-photons are not too close together.Some of the recent applications of the neutron activation technique havebeen concerned with trace impurities in semi-conductors. Analyses forarsenic in germanium copper in germanium,5s8 phosphorus insilic0n,~8~ arsenic in silicon,590 and various impurities in silicon 586 havebeen reported; a typical sensitivity is the determination of 3 x lo4 pg. ofarsenic in a l-g. sample of silicon.576 P.C . van Erkelens, Nature, 1953, 172, 357.677 A. E. Ballard, C . W. Zuehlke, and G. W. W. Stevens, ref. 506, p. 105.578 N. C . Baenziger, J . Chem. Phys., 1948, 16, 1175.579 W. A. Brooksbank, G. W. Leddicotte, and H. A. Mahlman, J . Phys. Chem.,580 A. A. Smales, ref. 506, p. 162.Idem, Ann. Reports, 1949, 46, 285.5a2 W. W. Meinke, Science, 1955, 121, 177.583 W. W. Meinke and R. E. Anderson, AnaZyt. Chenz., 1953, 25, 778.584 R. E. Connally and M. B. Leboeuf, ibid., p. 1095.585 G. H. Morrison and J. F. Cosgrove, ibid., 1955, 27, 810.586 A. A. Smales and L. Salmon, AnaZyst, 1955, 80, 37.5137 A. A. Smales and B. D. Pate, AnaZyt. Chem., 1952, 24, 717.sa8 G. Szekely, ibid., 1954, 26, 1500.589 J. A. J.ames and D. H. Richards, Nature, 1955, 176, 1026.1953, 57, 815.Idem, zbid., 1955, 175, 769376 ANALYTICAL CHEMISTRY.The technique has been applied to the determination of very smaUquantities of impurities in alurnini~m,~~1~ 592 aluminium a l l 0 ~ ~ , 5 9 3 mag-nesium,694 and iron.695 It has been suggested 696 that 6 x by weightof phosphorus in aluminium or aluminium oxide could be detennined quitereadily by this technique.The method is particularly suitable for analysesfor impurities in aluminium since only a negligible activity is induced in thematrix by slow neutrons; with fast neutrons, however, the reaction27Al(n, u)%Na occurs and it can interfere with the determination of sodiumin duminium.Neutron activation analysis has been used to determine sodium andpotassium in mixtures.The method has been applied to single nerve698 in which the sodium content may be only 1 pg. and the potassiumcontent not much greater; it was concluded that the method is about20 times as sensitive as methods with the flame photometer. The techniquehas been applied to the dating of potassium minerals.599 The rubidium andczsium contents of sea water and related materials have been measured; 586for sea water there was a preliminary concentration by means of a cation-exchange resin. The arsenic content of sea water can be measured directlyby neutron activatioamfor mixtures of rare earths byusing a small neutron source; in many cases the method is much superiorto spectrophotometric methods. Other examples of recent applications ofthe technique are the determinations of antimony,602 indi~m,~O~ cerium,604tantalum,528* 552, 60s and thorium.606The analyses considered so far have depended upon the occurrence of(12, 7 ) reactions.With slow neutrons 235U undergoes fission to give 1NBaamong many products, and the yield of 140Ba is a measure of the 235U contentof the original material. Several papers on the determination of uraniumby neutron activation have been p ~ b l i s h e d . ~ 7 - ~ ~ ~ ‘jLi readily undergoesa (aYt, a) reaction with slow neutrons; the tritium produced can be used todetermine 611 the original 6Li. This reaction is also used 632 in a deter-mination of the oxygen content of powdered beryllium; the beryllium isActivation analysis has been used591 R.C. Plumb and R. H. Silverman, Nucteonics, 1954, 12 [12], 29.592 P. Albert, M. Caron, and G. Chaudron, ref. 506, p. 171.593 B. M. Thall and B. Chalmers, J . Inst. Metals, 1950, 77, 79.594 G. J. Atchison and W. H. Beamer, Analyt. Chem., 1952, 24, 1812.595 P. Albert, M. Caron, and G. Chaudron, Compt. rend., 1953, 236, 1030.596 L. M. Foster and C. D. Gaitanis, Analyt. Chern., 1955, 27, 1342.597 P. R. Lewis, ref. 505, p. 381.588 R. D. Keynes and P. R. Lewis, J . Physiol., 1951, 114, 151.509 A. Moljk, R. W. P. Drever, and S. C. Curran, Nucleonics, 1955, 13 [2], 44.600 A. A. Smales and B. D. Pate, Analyst, 1952, 77, 188.601 W. W. Meinke and R. E. Anderson, Analyt. Chent., 1954, 26, 907.602 J. E. Hudgens and P. J. Cali, ibid., 1952, 24, 171.603 J.E. Hudgens and L. C. Nelson, ibid., p . 1472.604 L. E. Glendenin, K. P. Flynn, R. F. Buchanan, and E. P. Steinberg, ibid., 1955,605 A. Kohn, Chimie et Industvie, 1954, 71, 69.E. N. Jenkins, Analyst, 1955, 80, 301.607 A. A. Smales, ibid., 1952, 77, 778.608 A. P. Seyfang and A. A. Smales, ibid., 1953, 78, 394.609 A. P. Seyfang, ibid., 1955, 80, 74.H. A. Mahlman and G. W. Leddicotte, Analvt. Chem., 1955, 27, 823.611 L. Kaplan and K. E. Wilzbach, ibid., 1954, 28. 1797.612 R. G. Osmond and A. A. Smales, Analyt. Clzirn. Ada, 1954, 10, 117.27, 59BELCHER, BEVINGTO”, STEPHEN, AND WEST. 377mixed with 7 times its weight of lithium fluoride and irradiated. Thereaction 6Li(n, a)3H is followed by 160(t, n)l8F. The fluorine isotope isradioactive with a half-life of 112 min.; it is finally precipitated as PbClFfor assay. The oxygen content of the lithium fluoride may be significant inthis analysis.In some cases considerable care is needed in planning the analyses.The determination of arsenic in germanium 687 depends upon the reaction75As(12, but 76As can also be produced from the matrix by thereactions 74Ge(n, ~ ) 7 ~ G e and 75Ge -% 75As. 76As can also be formed frombromine and selenium by the reactions 79Br(n, a)76As and ?%e(n, p)7sAs,so these elements may interfere with the determination of arsenic. I n thedetermination of phosphorus in silicon,589 it must be noted that silicon canbe converted into an isotope of phosphorus thusmSi(n, y)31Si 3lSi B-L 3lpand the phosphorus so produced can contribute to the apparent phosphoruscontent of the silicon.Analyses for sulphur and phosphorus in magnesiumare complicated 594 if the specimen contains chlorine, because of the reactions35Cl(n, p)35S and 35Cl(n, a)32P. In analyses for trace impurities, the possi-bility of the matrix’s being converted into the impurity being studied mustalways be considered.Neutron activation has been used 613 to follow the sniall changes inbromine con tent caused by chemical manipulation of brominated poly-styrene. The technique has also been used in conjunction with paperchromatography. The bromine analogue of D.D.T. was located 568 on achromatogram by exposing the paper to a neutron flux and scanning for*2Br activity; similarly the a-, (3-, y-, and 8-isomers of hexachlorocycb-hexane were located 568 by means of the reaction 35Cl(n, p)35S. In applic-ations of these types difficulties may arise from losses of hydrogen[s2Br]bromide for example, from the unknown and standard, and theseshould be similar both chemically and physically.Ordinarily in activation analysis it is necessary that radioactive isotopesof fairly long half-life should be produced, although a half-life of only 22 min.for 233Th is sufficient to permit the determination 606 of thorium by thismethod.A development 614 in activation analysis is the irradiation togetherof the sample and a nuclear emulsion. The activities of short-lived isotopesmay be detected by the emulsion. In addition, elements which undergonuclear reactions but only to produce stable isotopes may also be detennined,for example 10B undergoes a (12, a) reaction readily and the a-particles canbe detected by the emulsion; this has also been described by Frenchauthors.615Photoneutron Methods.-The reaction 9Be(y, ~2)2~He occurs with y-raysmore energetic than 1.63 mev, and has been utilised 616 in a sensitive methodfor determining beryllium.The emitted neutrons are moderated and thendetected with lOB-enriched boron trifluoride counters. A lNSb source isa s M. H. Jones, H. W. MelvilIe, and W. G. P. Robertson, Nature, 1954, 174, 78;Ricerca sci., in the press.614 G. Mayr, Nucleonics, 1954, 12 [ S ] , 58.616 A. M. Gaudin and J . H. Pannell, Analyt. Chem., 1951, 23, 1261.. 615 H. Faraggi, A. Kohn, and J . Doumerc, Compt. rend., 1952, 255, 714378 ANALYTICAL CHEMISTRY.recommended ; the precautions needed in using a 1-curie y-source are con-siderable, but 1 p.p.m. of beryllium can be detected. The method is specificsince no other element has a photoneutron threshold below 2.04 mev whichcorresponds to the most energetic y-photons from %b; the presence oflithium, boron, or cadmium in the specimen is undesirable since theseelements have large cross-sections for the capture of thermal neutrons.A new method for deuterium analysis uses 617 the reaction 2D(yJ ~z)lH.The threshold is 2.23 mev and 24Na has been used as the y-source. Berylliumis the only element which can interfere, but samples should have similarcompositions so that moderation of the neutrons and absorption of they-rays are similar ; otherwise the purity of the sample is not critical.The reaction l60(y, n)150 forms the basis of a method 618 for determiningoxygen in organic compounds and metals. It is necessary to use y-rays ofenergies greater than 15-5 mev; the short-lived activity of 1 5 0 is measured.Another nuclear reaction involving the release of neutrons, viz. ,14N(d, T Z ) ~ ~ O , has been used G19 for analytical purposes. The mass ofnitrogen in a specimen is calculated from the observed 150 activity and thedeuteron flux; in metals, nitrogen contents as low as 1 p.p.m. have beenmeasured.Other Uses of Isotopes in Analysis.-The natural radioactivity of potas-sium, due to 40K, has been used 620a 621 in methods for determining thiselement; an accuracy of 1% or better is possible.510 The radiations from*7Rb, a naturally occurring isotope, are less penetrating than those fromUK, and the difference has been utilised622 in a method for determiningpotassium and rubidium in mixtures.The uses of labelled substances for analyses of high polymers have beens~mmarised.5~5 Accurate determinations of the amounts of initiators,retarders, and transfer agents incorporated in polymers during their pre-paration are possible ; the technique is valuable for analyses of co-polymersin those cases where the compositions of the monomer units are very similaror when one component is present only in small proportions. It is alsopossible to study similarly reactions between high polymers and materialsof low molecular weight, e.g., the quantity of P-benzoquinone which becomeschemically incorporated with poly(methy1 methacrylate) when mixtures ofthe quinone and the polymer are irradiated, has been found.623The X-ray absorption method for determining traces of heavy elementsin organic materials has been reviewed.624 In some cases there are con-siderable advantages in using radioactive isotopes as the sources of y- orX-rays for this purp0se.~~5 The isotope 55Fe which emits X-rays becauseof K-capture, is regarded G26 as the most suitable for the determination ofsulphur in hydrocarbons.617 C. P. Haigh, Nature, 1953, 172, 359; ref. 508, p. 101.61s R. Basile, J. HurC, P. LbvBque, and C. Schul, Compt. rend., 1954, 239, 422.619 P. Sue, zbid., 1955, 240, 88.620 K. C. Scheel, Angew. Chem., 1954, 66, 102.621 H. Dresia, 2. anaZyt. Chem., 1955, 144, 81.622 0. Gubeli and K. Stammbach, HeZv. Chim. Ada, 1951, 34, 1245, 1253.623 J. C. Bevington and A. Charlesby, Ricerca scz'., in the press.624 D. H. Whiffen, Ann. Reports, 1954, 51, 365.625 M. B. Leboeuf, D. G. Miller, and R. E. Connally, Nucleonics, 1954, 12 [8], 18.626 H. K. Hughes and J. W. Wilczewski, Analyt. Chem., 1954, 26, 1889BELCHER, BEVINGTON, STEPHEN', AND WEST. 379A neutron-scattering method for determining soil moisture has beendescribed.627 It depends upon the fact that hydrogen atoms are particu-larly effective in slowing down neutrons. A source of fast neutrons and adetector for slow neutrons are required. The method actually determinesthe hydrogen content of the soil, but practically all the hydrogen in mineralsoils is in the form of water.The amount of 8-radiation scattered from a sheet of material dependsupon the atomic number of the scatterer. This fact forms the basis for amethod for analysis of chromium-niobium alloys ; G28 the amount of radiationscattered is compared with that scattered from standards. The methodcan be extended to other alloys provided that the atomic numbers of thecomponents differ appreciably.Other applications of radioactive isotopes which are of some significancein analysis are the use of isotopes for calibrating m i ~ r ~ - ~ a l o r i m e t e r ~ , ~ 630the use of a radioactive falling-ball viscometer for opaque viscous liquids 631and the use of p-sources for dispersing static electricity on films andpowders.632J. C. B.R. BELCHER.J. C. BEVINGTON.W. I. STEPHEN.T. S. WEST.627 A. H. Knight and T. W. Wright, ref. 508, p. 111.63e P. Boivinet and E. Calvet, Comfit. rend., 1954, 238, 1995.6so W. B. Mann, J. Res. Nat. Bur. Stand., 1954, 52, 177.N. A. Bogdanov and V. F. Funke, Zavodskuyu Lub., 1955, 21, 181.J. GuCron, ref. 506, p. 6.See, e.g., P. S . H. Henry, ref. 506, p. 150