May, 1983 SUMMARIES OF PAPERS I N THIS ISSUESpectrophotometric Determination of Trace Amounts ofQuaternary Ammonium Salts in Drugs by Ion-pairExtraction with Bromophenol Blue and QuinineThe sensitive and selective method reported here is based on the reaction ofquinine cations with bromoplienol blue (HPJ3) to form a 1 : 1 complex anion,which, with a quaternary ammonium salt a t pH 0.7, is extractable intochloroform as an ion pair. Berberine and benzethonium were extracted inlarge amounts into chloroform with UPR only when quinine, in a pH 6.7buffered aqueous solution, co-existed with them. In adtlition, when tliisshowed a strong ion associate ability, then bcrbcrine antl benzcthonium couldreact in the organic phase with 131’13 to give a blue product. Tlie absorbanceof the ion associate in chloroform was measured a t 610 nm. Calibrationgraphs were linear in tlie range 0.5 x 10-6-3.0 x M for berbcrine andbenzetlionium.Molar absorptivities were 3.75 x lo4 1 mol-l cm-l for theberberine associate and 3.14 x lo4 1 mol-l cm-l for the benzethoniumassociate. The blue associate can be used for selective and sensitive spectro-photometric determination of berberine and benzethonium in multi-com-ponent drugs.Keywords : Rerberine nssay ; benzethoniunz assay ; co-extraction spectrophoto-metry ; bronzopkenol blue - quinine associateTADAO SAKAIDepartment of Chemistry, Gifu College of Dentistry, 185 1 Takano, Hozumi-cho,Gifu 501-02, Japan.Analyst, 1983, 108, 608-614.Simple Method for the Determination of Gypsum, withSome Observations on the Solubilities of Gypsum, Anhydrite,Calcite and DolomiteA rapid method is presented for the determination of gypsum and relatedminerals in natural antl synthetic materials, based on tlic extraction of calciumfrom the matrix material using slightly amnioniacal kvatcr as a solvent withsubsequent complcxometric titration of the calcium using 131)TA. Tlie resultscompare reasonably well with tliosc obtaincd by tlie conventional gravimetricprocedure.Tlic interferences due to other sparingly soluble calcium com-pounds, sucli as calcite antl dolomite, commonly found in conjunction withgypsum were examined, as were tlic solubilities of anhydrite, calcite anddolomite in both water and sodium chloride solution.‘The method is particu-larly suitable for industrial control and deposit assessment purposes.Keywords : Gypsum determination ; anhydrite ; calcite ; dolomite ; solubilityviiHENRY A. FONER and SARAH EHRLICHGeochemistry Department, Geological Survey of Israel, 30 NIalchei Israel Strect,Jerusalem, 95 501, Israel.Analyst, 1983, 108, 615-620...Vlll SUMMARIES OF PAPERS I N THIS ISSUEEffect of On-line Complex Formation Kinetics on theFlow Injection Analysis Signal : the SpectrophotometricDetermination of Chromium(V1)May, 1983The sensitivity of the flow injection analysis (FIA) method for determinationof chromium(V1) using lI5-dipheny1carbazide (DT’C) clepentls on the concentra-tion of the acid used in confluence with the I ) K solution.At low acid con-centrations slower on-line reaction kinetics are observed for Cr - DI’C complexformation. Hence the chemical contribution to the over-all dispersion valuecannot be ignored. This indicates that the best experimental conditions forthe static procedure may not always translate directly to the dynamic contli-tions of FIA. In the present instance the maximum signal is obtained withacid concentrations a t or above 0.80 M. Although sulpliuric acid may be used,as in the conventional procedure, the best working conditions are acliievedusing nitric acid.Keywords : Flow injection analysis ; on-line kinetics ; clwomiuiii ( V I ) determina-tionJOAO CARLOS DE ANDRADE, JULIO CESAR ROCHA, CELIO PASQUINIand NIVALDI BACCANUniversidade Estadual de Campinas, Instituto de Quimica,,C.P.6154,13100-Campinas,S%o Paulo, Brazil.Analyst, 1983, 108, 621-625.Titrimetric Determination of Some N- SubstitutedPhenothiazine DerivativesAn indirect titrimetric metliocl is described for the clctcwiiination of someN-substituted plienothiazine derivatives. The mcthotl involvcbs the use of1,3-dibro1iio-5,5-ti1~ietli~lliy~lantoi1i or lY-~~romosuccinimitlc as the titrant.A known excess o f citlier reagent is adtled and, after ;I specifid time, theresidual reagent is deterniinecl ioclinictrically. The proposctl mctliotl wasapplied to the analysis of pliarmaceutical preparations containing thc drugs,and the results obtained compared favourably with tliose obtained bypharmacopoeia1 methods.Keywords : N-Substituted Phenothiazine deteviiiination ; titrimetry ; 1,3-dibrovno-5,5-divnethyl?iydantoin ; N-bvovnosucciniiizideMOHAMED IBRAHIM WALASH, MOHAMED RIZK, ABDEL-MALIKABOU-OUF and FATHALLA BELALDepartment of Analytical Chemistry, Faculty of Pharmacy, Mansoura University,Mansoura, Egypt.Analyst, 1983, 108, 626-632.Ligand-exchange Reactions in the Analysis of Cobalt Complexesby Atomic-absorption SpectrophotometryShort PaPevKeywords : Ligand-exchange yeactions ; cobalt complexes ; ditliizone ; atomic-absorption spectrophotovnetryW.JAMES SWINDALL, DUNCAN THORBURN BURNS and ELMUGDADA. ALIDepartment of Analytical Chemistry, Thc Queens University of 13clfast, Iklfast,BT9 5AG.Analyst, 1983, 108, 633-636May, 1983 SUMMARIES OF PAPERS I N THIS ISSUEDifferential Determination of Cationic and Anionic Surfactantsin Mixtures by Two-Phase TitrationShort PaperKeyurovds : Two-filtrrse tityntion ; crrtionic and anionic surfactant deteriizination ;sodium tetvn~lte~~~lOornte titrant; tetrabroi?zo~Jienol~~~t~talein ethyl esterindicatovMASAHIRO TSUBOUCHIT,al,oratory o f Chcniistry, liochi Mcclical School, Oko, Nankoku, Kochi 781-51, Japan,and JOHN H. MALLORYPurex Corporation, 24600 South Main Strcct, Carson, CA 90749, USA.Analyst, 1983, 108, 636-639.Adsorption of Metals on Polypropylene During Cold VapourAtomic-absorption Determination of MercuryShort PaperKeywords : Mercury determination ; atomic-absorption spectrophotometry ;metal adsorption ; polypropyleneHART B.MAcPHERSON and SHIER S.BERMANDivision of Chemistry, National Research Council of Canada, Ottawa, Ontario,Canada, 1KA OR9.Analyst, 1983, 108, 639-641.Spectrophotometric Study of the Reaction of Titanium(1V) withChlorophosphonazo IShort Pa9erKeywords ; Titanium determination ; chlorophosphonazo I ; spectroplzoto-metryQIU XING-CHUAgricultural Science Research Institute of Ganzhou Prefecture, Jiangxi, China.and ZHU YING-QUANPO Box 82, Chengdu, China.ixAnalyst, 1983, 108, 641-644THE ANALYST May, 1983READER ENQUIRY SERVICEFor further information about any of the products featured in the advertise- fments in this issue, please write the appropriate A number in one of the 3 iPostage paid if posted in the British Isles but overseas readers must affixboxes below. g ia stamp.(Please use BLOCK CAPITALS)NAM E .........................................................................................................................................................................................OCCUPATION .................................................................................................................................................................ADDRESS .............................................................................................................................................................................SECOND FOLDPostageDo not affix Postage Stamps if posted inGt. 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