April, 1983 SUMMARIES OF PAPERS IN THIS ISSUESummaries of Papers in this IssueKinetic, Static and Stirring Errors of Liquid JunctionReference ElectrodesResponse characteristics of reference electrodes were determined by subjectingthem to large changes in ionic strength and transference. Commercial elec-trodes often gave surprisingly poor performance, exhibiting slow, inaccurateand stirring-dependent responses. Slow response is caused primarily bydiffusional entrapment of previously measured solutions within the junction.Large offsets at pH extremes or a t low ionic strength are caused by storage ofno-flow electrodes in standard buffers, junction charge and improper junctiongeometry. Stirring potentials are caused by shifts in offset error with localchanges in concentration at the junction surface.Adequate outward flow ordiffusion of junction electrolyte serves to suppress these anomalies. Referenceproblems are often undetectable in the standard pH buffers typically used forcalibration.Keywords : Reference electrode ; liquid junction ; offset error; kinetics ; stirringpotentialDONALD P. BREZINSKICorning Glass Works, Sullivan Research Park, Corning, NY 14831, USA.Analyst, 1983, 108, 425-442.Analytical Use of the Kinetics of Complex Formation :Simultaneous Determination of Iron and Cobalt byDifferential Kinetic MethodsThe kinetic determination of iron and cobalt mixtures without a prior separa-tion is described. The methods are based on the differential reaction ratebetween pyridoxal thiosemicarbazone and these metallic ions.Variousratios a t the M level of the two ions can be determined photometricallyby using either the “logarithmic extrapolation” or the “single-point” methods.These two methods are compared.Keywords : Iron and cobalt simultaneous determination ; pyridoxal thio-semicarbazone ; kinetics of complex formation ; differential kinetic methodsL. BALLESTEROS and D. PEREZ-BENDITODepartment of Analytical Chemistry, Faculty of Sciences, University of Cbrdoba,Cbrdoba, Spain.Analyst, 1983, 108, 443-451.Improvements to the Oxygen Flask Combustion Procedure forAssay of Halogenated Organic CompoundsAn improved oxygen flask procedure is described for the accurate, preciseand rapid determination of chlorine, bromine and iodine in halogenatedorganic compounds.Quantitative recoveries were achieved by using neutralhydrazine hydrate in the absorbing solution, which may be titrated potentio-metrically directly with silver nitrate solution. Hydrazine hydrate does notinterfere under acidic conditions. Accurate and precise results were obtainedwhen the equivalence points were determined by Gran’s method.Keywords ; Halogen determination ; oxygen flask combustion ; hydrazinehydrate ; potentiometric titration ; Gran’s methodDUNCAN THORBURN BURNS and BINOD K. MAITINDepartment of Analytical Chemistry, The Queen’s University of Belfast, Belfast,BT9 5AG.Analyst, 1983, 108, 452-456.iiApril, 1983 SUMMARIES OF PAPERS I N THIS ISSUEEvaluation of Equivalence Points in the Potentiometric Titrationof Mixtures of HalidesThe accura,te and precise location of the equivalence points in the potentio-metric titration of halide ions can be achieved numerically by using Gran’smethod.The results have been shown to be better by this method thanthose obtained on the same titration data by the differential methods ofKolthoff, of Fortuin and of Hahn.Keywords ; Equivalence points ; potentiometric titration ; halide ions ; Gran’sDUNCAN THORBURN BURNS, BINOD K. MAITIN and GYULA SVEHLAmethodDepartment of Analytical Chemistry, Queen’s University of Belfast, Belfast,BT9 5AG.Analyst, 1983, 108, 457-463.Flow Injection Voltammetric Determination of NitrateAfter Reduction to NitriteNitrate can be determined conveniently by chemical reduction to nitrite, whichis then injected directly into an acidic bromide eluent in a flow injection systemand monitored using its reduction signal a t a glassy carbon electrode held a t+0.3 V versus a saturated calomel electrode.Chemical reduction was bestcarried out on a batch basis but partial success was experienced in using amethod in which a nitrate sample solution was passed continuously through acadmium sponge column and then through the injection loop of the flowinjection valve from which aliquots were injected into the flow injectionsystem. Determinations were also made by injection of nitrate sample solu-tion directly into an acidic bromide eluent and reducing the nitrate on-line withcadmium wire.Keywords : Flow injection analysis ; voltammetry ; nitrate determination ;nitriteARNOLD G.FOGG, ANTOINE Y. CHAMS1 and MOHAMED A. ABDALLAChemistry Department, Loughborough University of Technology, Loughborough,Leicestershire, LE11 3TU.Analyst, 1983, 108, 464-469.Fully Automatic Flow Injection System for the Determination ofUranium at Trace Levels in Ore LeachatesAn automatic flow injection system is described for the determination ofuranium in ore leachates. Following injection from an autosampler, theleachate is extracted with a solution of tributyl phosphate in heptane, whichremoves uranium, and the organic phase is separated. The extract is reactedwith an ethanolic solution of 2-( 5-bromo-2-pyridylazo)-S-diethylami1iophenol(BrPADAP) and benzyldimethyltetradecylammonium chloride (zephiramine)and the resulting ternary complex with U(V1) is measured spectrophoto-metrically a t 579 nm.The lower limit of determination is 0.1 p.p.m. ofuranium and up to 50 samples per hour can be analysed. In terms of speedand sensitivity this improves significantly on published procedures usingsegmented flow systems. The technique is ideal for process control and canbe applied to the analysis of ores following mineralisation.Keywords : Flow injection ; ore leaclzates ; spectrophotometry ; uraniumdeterminationTHOMAS P. LYNCH, ARTHUR F. TAYLOR and JOHN N. WILSONChemical Analysis Branch, BP Research Centre, Chertsey Road, Sunbury-on-Thames,Middlesex, TWl6 7LN.Analyst, 1983, 108, 470-475Aj5riL, 1983 SUMMARIES OF PAPERS I N THIS ISSUEVolatilisation of Zirconium, Vanadium, Uranium andChromium Using Electrothermal Carbon Cup SampleVaporisation into an Inductively Coupled PlasmaZirconium, vanadium, uranium and chromium react with ammoniumchloride ( 7 9 ; iii/I’) when heated in an electrothermal carbon cup to form theircorresponding chlorides.These nictal chlorides are subsequently vaporisedinto an inductively coupled plasma for optical emission spectroscopy. Thepreferential lialide formation of these refractory elements in the electrothermalcarbon cup has alloxved their determinations to proceed with sub-nanogramdetection limits and adequate precision of about GO/, relative standarddeviation for 5-pl samples. Linear dynamic ranges span about three ordersof magnitude.Keywords : Metal clzloride formation ; electrothermal carbon cup vaporisation ;inductively coufiled plasizza ; optical emission spectroscopyKIN C.NG and JOSEPH A. CARUSODepartment of Chemistry University of Cincinnati, Cincinnati, OH 4522 1, USA.Analyst, 1983, 108, 476-480.Electrothermal Atomisation Atomic-absorption SpectrophotometricDetermination of Chromium(V1) in Urine by SolventExtraction Separation with Liquid Anion ExchangersAn electrothermal atomic-absorption spectrophotonietric determination ofchromium (VI) in urine samples is described. Tlic separation of these ionsfrom the biological matrix by using high relative molccular mass amines(such as Ambcrlite LA-I or LA-2 liquid anion exchangers) is also reported.Keywords : lien-avalent cJironii.unz ; liquid anion exchangers ; electvothermalnlor?iisntion atoiiaic-absovptio.tz spectrometry ; wine analysisCLAUD10 MINOIACentro Ricerchc di Fisiopatologia e Sicurczza del Lavoro, Fondazione Clinica delLavoro, Universitd di Pavia, Pavia, Italy.AMBROGIO MAZZUCOTELLIIstituto di Pctrografia, UnivcrsitA di Genova, Genoa, Italy.ALESSANDRO CAVALLERICattedra di Riedicina dcl Lavoro, Universitd di Modena, Modena, Italy.and VINCENZO MINGANTIIstituto di Chimica Generale ed Inorganica, UniversitA di Genova, Genoa, Italy.Analyst, 1983, 108, 481-484.Use of Laser Raman Spectrometry for a QuantitativeStudy of the Urea Synthesis under Process ConditionsPart I.A Feasibility StudyThe feasibility of laser Raman spectrometry for the in situ determination ofthe chemical cornposi tion during the synthesis of urea under process conditionshas been studied. Ranian bands suitable for quantitative analysis were foundfor all components. The use of an internal standard appears t o be essential.The influence of temperature and pressure upon niolar intensities has beenstudied for model Components and, as a result, for most components of theurea synthcsis, no effect of pressure is expected.By contrast, the Ramanspectra of all componcnts will bc affected by a change of temperature.Keywords : Laser Rainan spectroiiietry ; in situ analysis ; w e a syntlaesisMARTIN VAN ECK, JOHANNES P. J. VAN DALEN and LEO DE GALANLaboratory for Analytical Chemistry, University of Technology, Jaffalaan 9, 2628 BXDelft, The Netherlands.Analyst, 1983, 108, 485-491.vi SUMMARIES OF PAPERS IN THIS ISSUEDistribution of Zinc Amongst Human Serum Proteins Determinedby Affinity Chromatography and Atomic-absorptionSpectrophotometryApril, 1983Affinity chromatography for albumin has been coupled with electrothermalatomic-absorption spectrophotometry to determine the distribution of zincbetween albumin and globulin ligands in normal human serum.The pro-cedure is both simple and rapid and requires only 400 pl of serum for duplicateanalyses. There is no alteration in the distribution of zinc betwccn albuminand the globulins during the separation process and the total recovery ofzinc from the column is quantitative, 98.604. Albumin-bound zinc andglobulin-bound zinc are determined with relative standard deviations of 4.5and 5.9%, respectively.The distribution of zinc obtained is in very goodagreement with that found using more complex techniques.Keywords ; Zinc determination ; serum proteins ; afinity cliromatography ;atomic-absorption spectrophotometry ; kinetic immunoturbidimetryJOHN W. FOOTE and H. TREVOR DELVESChemical Pathology and Human Metabolism, Medical Faculty of the University ofSouthampton, South Laboratory and Pathology Block, Level D, SouthamptonGeneral Hospital, Tremona Road, Southampton, SO9 4XY.Analyst, 1983, 108, 492-504.Spectrofluorimetric Determination and Thin-layer ChromatographicIdentification of Selenium in FoodsA method is described for the determination of selenium in foods.Digestionof the samples and fluorimetric determination are based on the method ofMichie et al., with minor modifications. To confirm the results from aqualitative point of view, a new thin-layer chromatographic procedure isproposed.Keywords : Selenium determination ; food analysis ; spectrofluoviinetry ; thin-TERESA MORENO-DOMfNGUEZ, CONCEPCION GARCfA-MORENOand ABEL MARINfi-FONTDepartment of Bromatology, Toxicology and Chemical Analysis, Faculty ofPharmacy, University of Salamanca, Salamanca, Spain.Analyst, 1983, 108, 505-509.layer chromatography ; 2,3-diaminonaphthaleneChromatographic Separation of Chlorinated Hydrocarbons UsingColumns of Silica Gel of Varying Degrees of Porosityand ActivationA rapid metliocl for the separation of chlorinated pesticicles such as the di-chlorodiphenyltricliloroetliane ( m T ) group and dieldrin from polychlorinatedbiphenyls by porous deactivated silica gel co1umn chromatography isdescribed. The complete separation and quantitative recoveries obtainedallow a correct tletcrniination of tliesc compounds. This procedure is licl p-ful in niulti-pesticide residue analysis.Keywords : Polychlorinated biphenyls ; chlorinated pesticides ; porous silica gelcolumn cli voulzatograph yVITTORIO CONTARDI, RENZO CAPELLI, GILDA ZANICCHI andMARC0 DRAG0Istituto di Chimica Generale, Gruppo Ricerca Oceanologica-Genova, Universiti diGenova, Genoa, Italy.Analyst, 1983, 108, 510-514