ISSN:0003-2654    

DOI:10.1039/AN98207FX017

出版商:RSC    

年代:1982

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN98207BX019

出版商:RSC    

年代:1982

数据来源: RSC

摘要:

iV SUMMARIES OF PAPERS I N THIS ISSUE May, 1982Summaries of Papers in this IssueSpectrofluorimetric Determination of Inorganic AnionsA ReviewSummary of ContentsIntroductionMethods based on redox reactionsAppearance of fluorescenceAnions acting as oxidising agentsAnions acting as reducing agentsAnion-catalysed reactionsEnhancement of the oxidising properties of metal ions due to complexformation by anionsFluorescence quenchingAnions acting as oxidising agentsAnions acting as reducing agentsMethods based on formation of complexesFormation of binary complexesAnthraquinonesHydroxyflavonesKetonesOther reagentsFormation of ternary complexesHydroxyflavones - oxalic acidCalcein Blue - zirconiumBenzoin - mannitolMethods based on formation of ion-association complexesIon-association binary complexesIon-association ternary complexesFluorescence quenchingMethods based on substitution reactionsBy aluminiumBy thoriumBy magnesiumBy mercuryBy other cationsBy palladiumBy copperBy mercuryBy other cationsAppearance of fluorescenceMethods based on enzymatic reactionsDiscussionBorateCyanideOxalateFluorideIodideNitriteNitratePhosphateSulphideSulphateConclusionsAppendixReferencesKeywords : Review ; inorganic anions ; sPectro$uovimetryA.GOMEZ-HENS and M. VALCARCELDepartment of Analytical Chemistry, Faculty of Sciences, University of Cbrdoba,Cbrdoba, Spain.Analyst, 1982, 107, 465-494May, 1982 SUMMARIES OF PAPERS I N THIS ISSUESpectrophotometric Determination of Rhenium in Alkaline SolutionVThe reaction of perrhenate with hydroxylammonium chloride (NH,OHCl)has been studied.Hydroxylammonium chloride reacts with rhenium in8-10 M sodium hydroxide solution to produce a yellow complex which hasAmax. a t 300 nm with a mola rabsorptivity of 7.9 x lo3 1 mol-l cm-l. Thestoicheiometry of the complex has been studied spectrophotometrically usingdifferent procedures. A method for the spectrophotometric determination ofrhenium has been developed, and this has been applied to the determinationof rhenium in molybdenum - rhenium and tungsten - rhenium alloys.Keywords : Rhenium determination ; spectrophotometry ; hydroxylarnmoniurnchloride ; alloysL. V. BORISOVA, A. N. ERMAKOV and A.B. ISMAGULOVAVernadsky Institute of Geochemistry and Analytical Chemistry, USSR Academy ofSciences, Vorobjevskoe Shosse 47a, Moscow 117334, USSR.Analyst, 1982, 107, 495-499.Determination of Rhenium Based on the Formation of Rhenium(V1)Oxide Halide Complexes by Spectrophotometry and ElectronSpin Resonance SpectroscopyThe possibility of obtaining solutions of rhenium(V1) compounds and theiranalytical applications has been studied. The rhenium(V1) compoundsformed, ReOC1,- and ReOBr,, are characterised by specific absorbance spectraand electron spin resonance (ESR) spectra. New quantitative methods ofrhenium determination were devised. The formation of ReOBr, in sulphuricacid from the Re0,- ion and KBr was used for the development of a selectivespectrophotometric method for the determination of rhenium and the abilityof ReOBr, to be extracted into organic solvents was used for rhenium deter-mination by ESR.On the basis of ReOC1,- formation, a quantitative method for the deter-mination of rhenium by the spectrophotometric titration of Re0,- in amixture of sulphuric and hydrochloric acids using an iron(I1) solution wasdevised.The methods were also applied to alloys.Keywords : Rhenium determination ; rhenium ( V I ) oxide halide complexes ;spectrophotometry ; ESR spectroscopy ; alloysL. V. BORISOVA, A. N. ERMAKOV, Y e . I. PLASTININA, 0. D. PRASO-LOVA and I. N. MAROVVernadsky Institute of Geochemistry and Analytical Chemistry, USSR Academy ofSciences. Vorobjevskoe Shosse 47a, Moscow 117334, USSR.Analyst, 1982, 107, 500-504Vi SUMMARIES OF PAPERS I N THIS ISSUECombined Ion Exchange - Spectrophotometric Method for theSimultaneous Determination of Vanadium and Cobalt inBiological MaterialsMay, 1982A combined anion exchange - spectrophotometric method has been developedfor the determination of vanadium and cobalt in biological materials.Asample is dry ashed a t 420 "C, the ash (ca. 0.5 g) is decomposed with a mixtureof perchloric, nitric and hydrofluoric acids, and finally is taken up in hydro-chloric acid. The metals are adsorbed by anion exchange on an AmberliteCG 400 (SCN-) column from a dilute ammonium thiocyanate - hydrochloricacid solution. The adsorbed vanadium and cobalt are separated chromato-graphically by elution with 12 M hydrochloric acid and 2 M perchloric acid,respectively.Both fractions of vanadium and cobalt are subsequentlypurified by anion exchange from 0.1 M hydrochloric acid - 3% V / V hydrogenperoxide for vanadium and 6 M hydrochloric acid for cobalt. Vanadium andcobalt in the effluents are determined spectrophotometrically with 4- (2-pyrid-y1azo)resorcinol. Results for the determination. of vanadium and cobalt invarious materials of biological origin and in NBS standard biological samplesare given.Keywords : Simultaneous determination of vanadium and cobalt ; biologicalmaterials ; spectrophotometryT. KIRIYAMALaboratory for Chemistry, Faculty of Education, Kagoshima University, Kagoshima,Japan.and R. KURODALaboratory for Analytical Chemistry, Faculty of Engineering, University of Chiba,Yayoi-cho, Chiba, Japan.Analyst, 1982, 107, 505-510.Liquid - Liquid Extraction Combined with Atomic- absorptionSpectrometry for Determination of Copper in Waters, Foods andAnalytical Reagents Using 1,2 - Naphthoquinone ThiosemicarbazoneAn atomic-absorption spectrometric metho$ for the determination of traceamounts of copper in solution with 1,2-naphthoquinone thiosemicarbazoneis described.This compound reacts with copper in a weakly acidic mediumto produce a complex that can be extracted into isobutyl methyl ketone.The atomic absorption of the organic phase is measured at 324.8 nm: Thesensitivity of the method is 0.6 ng ml-l for 1% absorption in aqueous solutionand the presence of several milligrams of 55 foreign ions is tolerated.Themethod has been applied successfully to the analysis of waters, foods andanalytical reagents.Keywords : copper determination ; atomic-absorption spectrometry ; 1,2-naphthoquznone thiosemicarbazone; waters, foods and analytical-reagentanalysisM. SILVA and M. VALCARCELDepartment of Analytical Chemistry, Faculty of Sciences, University of Cordoba,Cordoba, Spain.Analyst, 1982, 107, 511-518May, 1982 SUMMARIES OF PAPERS IN THIS ISSUESpectrophotometric Determination of Uranium(V1) in PhosphoricAcid by Means of Solvent Extraction with Mixtures ofTOPO and BiphenylThe variations in the distribution coefficients of twelve metals and uraniumbetween nitric acid or hydrochloric acid - TOPO (trioctylphosphine oxide)systems have been studied as functions of the concentration of nitric acid,hydrochloric acid and TOPO and temperature (in the range 70-80 "C),employing biphenyl as the diluent for TOPO.The formula UO,(NO,!,-(TOPO), can be. assigned to the complex. Uranium in a phosphoric acidsolution is quantitatively extracted from 2 mol dm-3 nitric acid into moltenTOPO - biphenyl at about 70 "C. . The organic phase separates out as a solidon cooling and is dissolved in ethanol. The uranium in this solution is thendetermined spectrophotometrically with 1 - (2-pyridylazo) naphth-2-01. Beer'slaw holds in the range 1-8 p.p.m. of uranium, and the relative standard devi-ation for 10 determinations was 2. l yo.Keywords : Uranium( V I ) ; spectrophotovnetry ; phosphoric acid; TOPO -biphenyl mixtures ; solvent extractionTAKEHIRO KOJIMA, YASUMASA SHIGETOMI, HIDEAKI KAMBA andHIROBUMI IWASHIRODepartment of Chemistry, Okayama College of Science, Ridai-cho, Okayama 700,Japan.TAKABUMI SAKAMOTODepartment of General Education, Okayama College of Science, Ridai-cho, Okayama700, Japan.and AKIRA DO1Department of Applied Chemistry, Okayama College of Science, Ridai-cho, Okayama700, Japan.Analyst, 1982, 107, 619624.Determination of Obscuration. Part 11.Determination ofDissolved Solids Content in Alcoholic Beverages :Collaborative StudyNine laboratories have participated in a collaborative study analysing 22samples of spirits to determine the reliability of a modified method for thedetermination of the dry extract concentration.Statistical evaluation ofthe results revealed acceptable standard errors up to a concentration ofabout 20 g 1-1 for use in the determination of spirit obscuration.Keywords : Obscuration ; collaborative study ; dissolved solids content ; alcoholicbeveragesJAN KOVARLaboratory and Scientific Services Division, Revenue Canada, Customs and Excise,Ottawa, Canada, K1A L05.Analyst, 1982, 107, 525-532viii SUMMARIES OF PAPERS IN THIS ISSUEDetermination of Obscuration, Part 111, Establishment of theObscuration Factor in Alcoholic Strength DeterminationMay, 1982The empirical value of the obscuration factor in determinations of alcoholicstrength has been established as being 0.3. When applied to a series of 19samples, the mean deviation of the calculated strength, with obscurationconsidered, from the true alcohol strengths determined after distillation is0.02% V / V with a standard error of the mean of 0.05% V / V .It is recom-mended that the dry extract obscuration procedure be used in preference tothe distillation procedure when the dry extract concentration does not exceed10 g 1-1.Keywords : Obscuration ; ethanol ; alcoholic strength determinationJAN KOVAR and MARIANNA LEUNGLaboratory and Scientific Services Division, Revenue Canada, Customs and Excise,Ottawa, Canada, K1A OLB.Analyst, 1982, 107, 533-537.Analytical Figures of Merit for Low -temperature Luminescenceof Polynuclear Aromatic CompoundsLow-temperature (77 K) luminescence figures of merit for several polynucleararomatic compounds are presented.Fluorescence figures of merit for 41compounds are included with detection limits ranging from 0.001 to 0.1 pg ml-1for most compounds with an average relative standard deviation of 5.4%.Phosphorescence figures of merit for 60 compounds are included with detectionlimits rangmg from 0.0004 to 4 pg ml-l and an average relative standarddeviation of 5.8%.Keywords : Polynuclear aromatic compounds ; low-temperature luminescence ;figures of meritE. L. INMAN, Jr., A. JURGENSEN and J. D. WINEFORDNERDepartment of Chemistry, University of Florida, Gainesville, FL 3261 1, USAAnalyst, 1982, 107, 538-543.Use of Chiral Lanthanide Shift Rwgents for the Nuclear MagneticResonance Spectrometric Determination of AmphetamineEnantiomersSynthesised tris(D,D-dicampholylmethanato)europium(III) [Eu(dcm),] andfive commercially available chiral lanthanide shift reagents are used toresolve the nuclear magnetic resonance spectra of the enantiomeric C-CH,protons in D- and L-amphetamine. The chemical shift difference betweenthese enantiomeric protons induced by the six shift reagents are evaluatedfor their prospective use in enantiomeric identification and determination.The base-line resolution induced by Eu (dcm), renders the enantiomeric deter-mination feasible without using any special quantitation technique.Keywords : Chiral lanthamide shaft reagent ; amphetamines ; enantiomers ;nuclear magnetic resonance spectrometry ; chemical shift digerenceJUEI H. LIU and J. T. TSAYDepartment of Criminal Justice, University of Illinois a t Chicago Circle, Chicago,IL 60680, USA.Analyst, 1982, ~ 107, 544-549

ISSN:0003-2654    

DOI:10.1039/AN98207FP041

出版商:RSC    

年代:1982

数据来源: RSC

摘要:

May, 1982 SUMMARIES OF PAPERS I N THIS ISSUEGas-chromatographic Determination of 1 - (2-Chloroethyl) -3-(trans-4-methylcyclohexy1)- 1 -nitrosourea (Methyl- CCNU)Tetrahydroborate( 111)Part 11. Reduction to Semicarbazide with SodiumReduction of methyl-CCNU t o the semicarbazide has been utilised in thedevelopment of an assay for the drug following its extraction from urine.Keywords : Methyl-CCN U determination ; sodium tetrahydroborate(III)reduction ; semicarbazide ; gas chromatographyB. CADDY and 0. R. IDOWUForensic Science Unit, Department of Pharmaceutical Chemistry, University ofStrathclyde, Royal College Building, 204 George Street, Glasgow, G1 IXW.Analyst, 1982, 107, 550-555.Gas-chromatographic Determination of 1 - (2-Chloroethyl) -3-(trans-4-methylcyclohexyl) - 1 -nitrosourea (Methyl- CCNU)Part 111.Denitrosation to the Parent UreaDenitrosation of methyl-CCNU in situ and trifluoroacetylation of the resultingurea has been employed for the gas-chromatographic determination of thedrug in urine samples obtained from a patient. Plasma samples require tobe extracted prior to analysis by this procedure. The chemical stability ofmethyl-CCNU in urine has been assessed.Keywords : Methyl-CChT U determination ; peroxyacid denit rosation ; gaschromagraphy ; urinary excretion ; drug stability in urineB. CADDY and 0. R. IDOWUForensic Science Unit, Department of Pharmaceutical Chemistry, University ofStrathclyde, Royal College Building, 204 George Street, Glasgow, G1 1 XW.Analyst, 1982, 107, 556-565.Flow Injection Voltammetric Determination of Phosphate :Direct Injection of Phosphate into Molybdate ReagentPhosphate can be determined precisely as molybdophosphate by flow injectionanalysis using a glassy carbon electrode as a voltammetric detector.Thesample solution (25 pl, 1 x 10-'-5 x 1 0 - 4 M in phosphate) is injected intoan eluent which is 2o/b vn/V in ammonium molybdate and 0.6% V/Vin con-centrated sulphuric acid. Molybdophosphate, which is determined byreduction a t the glassy carbon electrode, is fully formed when a 3-m delaycoil (0.58 mm i.d.) is incorporated before the detector and a flow-rate of4 ml min-l is used.Keywords : Voltammetry ; pow injection analysis ; phosphate determination ;direct injection ; molybdate reagentA. G.FOGG and N. K. BSEBSUChemistry Department, Loughborough University of Technology, Loughborough,Leicestershire, LEll 3TU.A%alyst, 1982, 107, 566-570.iX SUMMARIES OF PAPERS IN THIS ISSUE May, 1982Determination of Sulphur in Semiconductor - grade Indium andIndium Phosphide by Cathodic-stripping VoltammetryA procedure is presented for the determination of sulphur in indium andindium phosphide within the range 0.01-100 p.p.m. by mass, based uponhydrogen sulphide evolution and differential-pulse cathodic-stripping voltam-metry of the sulphide ion. Good recoveries of sulphide added to indium aredemonstrated. Agreement with results obtained by spark-source massspectrometry and reproducibilities a t 0.1 and 1 p.p.m. levels by mass aresatisfactory. Sulphur concentrations a t the level of 100 p.p.m.by massfound in sulphur-doped indium phosphide are in agreement with themeasured electrical carrier concentrations. Use of the procedure in estab-lishing the sources of sulphur contamination in the liquid-phase epitaxialgrowth of indium phosphide layers is discussed briefly.Keywords : Sulphur determination ; indium ; indium Phosphide ; semi-conductor-grade materials ; cathodic-stripping voltammetryC. R. ELLIOTT and SHEILA O’BRIENBritish Telecom Research Laboratories, Martlesham Heath, Ipswich, IP5 7RE.Analyst, 1982, 107, 57 1-576.Determination of Ipronidazole in Pre-mixes for Additionto Animal FeedsReport prepared by the Medicinal Additives in Animal FeedsSub-committee (A).Keywords : Ipronidazole determination ; pre-mixes ; animal feeds ; spectro-photometryANALYTICAL METHODS COMMITTEEThe Royal Society of Chemistry, Burlington House, Piccadilly, London, W1V OBN.Analyst, 1982, 107, 577-578.Effect of Heating Proteins in a Vacuum on Their Assay bythe Lowry and Biuret MethodsShort PaperKeywords 1 Protein assay ; Lowry method; biuret method ; vacuum heating;removal of interferencesH.P. S. MAKKAR, 0. P. SHARMA, R. K. DAWRA and S. S. NEGIBiochemistry Laboratory, Regional Research Station, Indian Veterinary ResearchInstitute, Palampur (H.P.) 176 061, India.Analyst, 1982, 107, 579-582May, 1982 SUMMARIES OF PAPERS IN THIS ISSUESpectrophotometric Determination of Microgram Amounts ofVanadium(V) with p - Sulphobenzeneazo-4- (2,3-dihydroxypyridine)Short PaperKeywords : Vanadium( V ) determination ; spectrophotometry ; p-sulpho-benzeneazo-4- (2,S-dihydroxypyridine)YOGENDU SHARMALaboratoire de Chimie Physique et Electrochimie, Ecole Nationale Superieure deChimie de Strasbourg, 1 Rue Blake-Pascal, 67008 Strasbourg, France.Analyst, 1982, 107, 582-585.Fluorimetric Determination of Acetaminophen as itsDansyl DerivativeShort PaperKeywords : A cetaminophen determination ; fluorimetry ; dansyl chlorideAYSEL OZTUNqFaculty of Pharmacy, University of Istanbul, Istanbul, Turkey.Analyst, 1982, 107, 585-587.Mathematical Model of Electrothermal Atomisation Signals Basedon Free Atom RedepositionCommunicationKeywords ; Electrothermal atomisation ; transient signal shape ; mathematicalmodel; redeposition of free atomsJOSEF MUSIL and IVAN RUBESKAGeological Survey of Czechoslovakia, MalostranskC 19, 1 18 2 1 Prague 1, Czecho-slovakia.Analyst, 1982, 107, 588-590.xAThe AnalystNOW AVAILABLE SEPARATELYThe Analyst is an international journal of high repute containing original papers on thetheory and practice of all aspects of analytical chemistry.It is of interest to workers in awide range of fields including pharmaceuticals and drugs, environmental analysis, air andwater pollution, food analysis, forensic analysis, clinical analysis, metals and metallurgy,pesticides, agrochemicals, animal feedstuffs, water analysis. All modern techniques arecovered with a high proportion of papers on atomic absorption and related spectroscopictechniques, chromatography and electrochemical methods.The Analyst provides complete coverage of all major developments and includes paperswith a strong practical bias as well as papers of a theoretical nature.For the first time since 1954 The Analyst is available separately and does not have to besubscribed to in conjunction with Analytical Abstracts.12 issues per annum ( lus index)1982 Subscription: Uk €85.00, US $201.00, Rest of World €90.00Orders should be sent to :The Royal Society of Chemistry,Distribution Centre, Blackhorse Road,Letchworth,Herts.SG6 1HNTHE ROYAL SOCIETY OF CHEMISTRYAnnual Reports onAnalytical AtomicSpectroscopy VOI. 10Edited by J. 6. Dawson and 6. L. SharpThis volume reports on current developments inall branches of analytical atomic emission,absorption and fluorescence spectroscopy withreferences- to papers published and lecturespresented during 1980.Much of the informationis in tabular form for ease of reference.Hardcover 342pp 0 85186 717 0 f36.00 ($80.00)Still available:Vol. 3 (1973) 0 85990 253 6 f10.50 ($22.00)Vol. 4 (1974) 0 85990 254 4 f 15.00 ($32.00)Vol. 5 (1975) 0 85186 757 X f18.50 ($39.00)Vol. 6 (1976) 0 85186 747 2 f23.50 ($50.00)Vol. 7 (1977) 0 85186 737 5 f22.75 ($48.00)Vol. 8 (1978) 0 85186 630 1 f22.75 ($48.00)Val. 9 (1979) 0 85186 727 8 f34.00 ($72.00)Orders to The Royal Society of Chemistry,Distribution Centre, Blackhorse Road,Letchworth, Herts SG6 1HNTHE QUEEN’SUNIVERSITYOF BELFASTMSc COURSE inANALYTICAL CHEMISTRYApplications are invited for admission to thisestablished 12 month full-time MSc coursewhich provides a comprehensive training inthe theory and practice of modern chemicaland instrumental methods of analysis.Applicants should normally possess anhonours degree (or equivalent) in chemistryor cognate subjects. Part-time courses areavailable.The Science and Engineering ResearchCouncil has recognised the course for tenureof its Advanced Course Studentships.A description booklet and application formscan be obtained from Professor D. ThorburnBurns, Dept. of Chemistry, Queen’s Universityof Belfast, Belfast B l 7 1 NN, Northern Ireland.A205 for further information. See page xi

ISSN:0003-2654    

DOI:10.1039/AN98207BP047

出版商:RSC    

年代:1982

数据来源: RSC

摘要:

May 1982 The Analyst Vol. 107 No. 1274 Spectrofluorimetric Determination Anions A Review A. Gomez-Hens and M. Valchrcel of Inorganic Department of Analytical Chemistry Faculty of Sciences University of Cdrdoba Cdrdoba Spain Summary of Contents Introduction Methods based on redox reactions Appearance of fluorescence Anions acting as oxidising agents Anions acting as reducing agents Anion-catalysed reactions Enhancement of the oxidising properties of metal ions due to complex formation by anions Fluorescence quenching Anions acting as oxidising agents Anions acting as reducing agents Methods based on formation of complexes Formation of binary complexes Anthraquinones H ydrox y flavones Ketones Other reagents Formation of ternary complexes Hydroxyflavones - oxalic acid Calcein Blue - zirconium Benzoin - mannitol Methods based on formation of ion-association complexes Ion-association binary complexes Ion-association ternary complexes Fluorescence quenching Methods based on substitution reactions By aluminium By thorium By magnesium By mercury By other cations By palladium By copper By mercury By other cations Appearance of fluorescence Methods based on enzymatic reactions Discussion Borate Cyanide Oxalate Fluoride Iodide Nitrite Nitrate Phosphate Sulphide Sulphate Conclusions Appendix References Keywords Review ; inorganic anions ; spectrofluorimetry 46 466 GOMEZ-HENS AND VALCARCEL SPECTROFLUORIMETRIC Analyst VOZ.I07 Introduction Anions feature significantly in many areas of science and technology and accordingly their determination is important.In recent years spectrofluorimetry has become a widely used technique in many laboratories as it has clear advantages over photometry in terms of sensitivity and selectivity in most instances. Although there are several books on the deter-mination of anions such as those of Williams1 and Boltz,2 there does not appear to have been any systematic study of the spectrofluorimetric determination of inorganic anions. A critical study of spectrofluorimetric methods described for the micro-determination of inorganic anions in various materials up to 1980 is presented. There is a general belief that these methods are based on a phenomenon of fluorescence quenching but nevertheless 70% of them are based on phenomena of appearance of fluorescence which gives better selectivity and sensitivity.The diverse fluorimetric methods for the determination of each of the anions are summarised in the Appendix. The reagents used the type of method the spectral characteristics the reaction conditions the sensitivity and the interferences are included. Taking into account the reaction on which each procedure is based the methodology of the spectrofluorimetric determination of anions may be divided into methods based on redox reactions formation of complexes formation of ion association complexes substitution reac-tions and enzymatic reactions. In this review the methods are discussed critically on this basis. Methods Based on Redox Reactions These methods are divided into methods of appearance of fluorescence and methods of fluorescence quenching according to the sign of the slope of the calibration graph.Appearance of Fluorescence Anions acting as oxidising agents In this section dehydrogenation reactions of organic compounds are included as oxidation react ions. A method based on the increase in the fluorescence intensity of 5-aminofluorescein when it reacts with nitrite has been proposed for the determination of this anion.3 The reaction has not been studied but the authors propose the following mechanism : H O ~ O H C I - HCI HOT / / HCI-+ HN02 COOH COOH / \ Na+o-yo \ J / Na+oTo / A - COO-Nai COO-Na' -\ I N=NO- Na+ N=NOH The shape of the calibration graph depends on the dye concentration and the nitrite working In general as the 5-aminofluorescein concentration decreases the calibration graph range May 1982 DETERMINATION OF INORGANIC ANIONS.A REVIEW 467 curves. It is conceivable that there is another reaction or other reactions present that affect the fluorescence intensity. Other methods for the determination of nitrites are based on the formation of triazoles. Thus nitrite has been determined with 2,3-diaminonaphthalene which is transformed into 2,3-naphth~triazole~ : H Nitrate does not interfere in this method but it can be determined by reduction to nitrite with hydrazine s ~ l p h a t e . ~ The method has been developed for use in air-pollution studies. A sensitive fluorimetric method has been proposed for measuring nitrite ions based on the diazotisation of 9-chloroaniline and coupling with 2,6-diamino~yridine.~ The resulting azo product then is further derivatised with ammoniacal copper(I1) sulphate to produce a highly fluorescent triazole compound in acidic media that is extracted into benzene.This is probably due to a proton transfer between the excited hydrogen-bonded aminopyridine and hydroxide ion followed by radiationless decay of the imine anion. Although this procedure is lengthier than the Griess method it provides a five-fold increase in sensitivity of nitrite detection. A method has been described for the determination of persulphate in flour and dough.’ The procedure involves the extraction of the flour with water and the re-oxidation of leucofluor-escein to fluorescein through the action of the persulphate ion.Under controlled conditions, the intensity of the developed fluorescence bears a reproducible relationship to the persulphate content . Zarembski and Hodkinson* have proposed a method for the determination of oxalic acid in blood and other biological materials. Initially oxalic acid is separated from interfering substances by extraction with tributyl phosphate followed by coprecipitation with calcium sulphate. The precipitated oxalic acid is then reduced with electrolytic zinc to glyoxylic acid which is coupled with resorcinol (1,3-dihydroxybenzene) to form a coloured fluorescent complex. The method is sensitive and very specific. An automated method for the determination of nitrate in a wide variety of natural waters and sediments has been developed.9 This method is based on the considerable increase in the fluoresecence intensity of 2,2’-dihydroxy-4,4’-dimethoxybenzophenone (I) in the presence of nitrate in a medium with a relatively high acid concentration.Although the authors did not study the reaction it is possible that oxidation of the reagent takes place because other oxidant ions such as chromium(V1) and vanadium(V) give the same reaction with similar benzophenones. The fluorescence intensity increases when the concentration of sulphuric acid increases. Hydroxide ion considerably quenches the fluorescence. I Resorcinol has been proposed as a fluorimetric reagent for the determination of nitrate and nitrite.1° The author suggested the following mechanism for the reaction of nitrate chloride ion catalyses the conversion of nitrate into nitrite the resultant nitrite reacts with resorcinol to produce the nitroso compound which reacts with excess of resorcinol to form a reddish violet species.This reaction product exhibits intense fluorescence in ammoniacal solution and is probably a phenoxazine derivative 468 GOMEZ-HENS AND VALCARCEL SPECTROFLUORIMETRIC Analyst VoZ. I07 Anions acting as reducing agents A method has been proposed for the determination of cyanide based on its reaction with chloramine-T and nicotinamide.ll Cyanide is converted into cyanogen chloride with chloramine-T and this cleaves the pyridine ring of nicotinamide (Von Braun reaction) giving a product which has a strong blue fluor-escence in alkaline medium. The method has been applied to the determination of free hydrogen cyanide in vapour streams of Tabun (ethyl dimethylphosphoramidocyanidato vapour) .Guilbault and Kramer12 have proposed a specific method for the determination of cyanide based on its reaction with quinone monoxime benzenesulphonate ester giving a green fluor-escent compound. In a later paper13 these authors reported the reaction of cyanide with several quinones and quinone derivatives 9-benzoquinone N-chlorobenzoquinoneimine and substituted auinone monoxime benzenesulphonate esters and ethers. All of these compounds There are few methods in which the anion acts as a reductor. react specifiLally with cyanide to give cyanide with p-benzoquinone is fluorescent products.14 The proposed reaciion of In general all of the products have approximately the same excitation and emission wave-lengths 440 and 500 nm respectively.Substitution on the quinone ring decreases the fluorescence of the product and the rate of reaction. The order of fluorescence intensity and the rate of reaction increase in the following order of solvents used dioxane < ethyl formate < 2-methoxyethanol < methanol < acetonitrile < dimethylformamide < dimethyl sulphoxide. This parallels the order of the dielectric constants of the solvents. Oxalate has been determined by reduction of non-fluorescent Ce(1V) to fluorescent Ce(III).15 Other reductor ions give the same reaction. Anion-catalysed reactions The previously described reaction for determination of oxalate is catalysed by several ions, including iodide.Bonavita16 studied the reaction of pyridoxal and pyridoxal5-phosphate with cyanide. This anion produces a catalysed oxidation of pyridoxal to the lactone of 4-pyridoxic acid.17 The rate of the reaction is measured by measuring the fluorescence intensity. The method consists in treating cyanide with pyridoxal at pH 7.5 and measuring the fluorescence intensity at pH 10. Morgan and Wayls have applied the method to the determination of cyanide in biological fluids. An extensive study of the kinetics and mechanism of the reaction between nitrate and bianthronyl in concentrated sulphuric acid has been carried out .19 Initially nitrate reacts with sulphuric acid giving the nitronium cation which acts on the bianthronyl molecule : A method for the determination of iodide was also described.0 0 NOz' C 4 L + By different oxidative paths C (coloured species) and L (luminescent compound) are formed. L in subsequent steps yields anthraquinone. Bianthronyl first degrades via a bianthronyl May 1982 DETERMINATION OF INORGANIC ANIONS. A REVIEW 469 nitronium complex to anthronyl cation (A+) and anthrone (A) and later by different oxidative paths these are transformed into anthraquinone. The authors differentiated between the final product (Aex 286 A, 422 nm) and the anthra-quinone (Aex 285 Ae 420 nm) but as can be observed by their spectral characteristics these compounds are practically the same. Enhancement of the oxidising properties of metal ions due to complex formation by anions A method for the determination of phosphate has been described in which phosphate is converted into hexadimolybdatophosphate which then reacts with non-fluorescent thiamine to produce the highly fluorescent thiochrome (11).Initially qualitative detection of phosphate with thiamine was proposed20 and later, quantitative determination was studied.21 The method has been applied to the determination of inorganic phosphorus in renal tubular fluid.22 If the sample has a high protein concentra-tion e g . plasma this can be removed previously. Leucofluorescein is oxidised to fluorescein by the action of copper(I1) when cyanide is present in the medium.23 The fluorescence intensity is a linear function of the cyanide con-centration at low concentrations and the standard deviation is about 10%.Fluorescence Quenching Anions acting as oxidising agents Nitrates oxidise fluorescein in a concentrated sulphuric acid medium to form a non-fluorescent product .24 As fluorescein fluoresces and the reaction product does not nitrate can be determined by the measurement of the fluorescence suppression. The authors have not determined the structure of the reaction product but according to the Colour Index,25 fluor-escein reacts with nitrate in concentrated sulphuric acid to form Solvent Orange 16 (111), which has no fluorescence and is possibly the reaction product. o:13gX:::oi \ Ill A method for the determination of sulphur dioxide as sulphite by reaction with formaldehyde The simulated samples of trapped sulphur and 5-aminofluorescein has been proposed.2 470 GOMEZ-HENS AND VALCARCEL SPECTROFLUORIMETRIC Analyst VOZ.107 dioxide were made by dioxide dissolution of Na,S,O in a solution with Na,HgCl and later reaction with formaldehyde. The aldehyde - bisulphite complex formed oxidises 5-amino-fluorescein to a non-fluorescent product. 6 H CI-+ HOCHzS03H +NH&I- HYCHZS03HCI-The probable result of the Schiff reaction is the formation of a quinoid structure. This structure shifts the double bond on the central (pyran) carbon atom so that the quinone in the upper ring is no longer the dominant structure and the resulting compound is no longer fluorescent. Benzidine has been used for the determination of microgram amounts of nitrite.,' This anion oxidises the benzidine and produces a shift in its emission maximum from 387 to 348 nm and in its excitation maximum from 295 to 275 nm.Also the intensity decreases by about two thirds. Anions acting as reducing agents The oxidation of thiamine to thiochrome by oxidants such as permanganate is subject to interference by sulphides in the medium28 because of the involvement of two competing reac-tions with permanganate that of oxidation of thiamine and that of sulphide. A quenching method to determine sulphide has been proposed with excellent reproducibility but diverse ions can interfere by reacting with sulphide thiamine or permanganate. Bromide has been determined by a method based on the quenching by bromine of the fluorescence of fluore~cein.~~ It has been applied to measurement of bromine aerosols and airborne particulates.Finally a special method for the determination of cyanide is based on the inhibiting action of this anion on the chemiluminescence of luminol (IV) with hydrogen peroxide in the presence of copper(I1) .30 The induction period increases with increase in the concentration of cyanide and the logarithm of the induction period is proportional to the concentration of cyanide. IV Methods Based on Formation of Complexes In these methods the anion reacts with either one or two reagents giving rise to a binary Borate is the most common anion determined by this or ternary fluorescent complex. methodology. Formation of Binary Complexes Only the borate ion has been determined by formation of binary fluorescent complexes. To systematise the discussion of the numerous methods proposed they will be treated according to the type of organic reagent utilised.A nthraquinones only a few have been applied to the fluorimetric analysis of this anion. quinones are shown in Table I. Neither of these methods is based on the phenomenon of quenching. Although many anthraquinones have been described as photometric reagents of borate, Some of these anthra May 1982 DETERMINATION OF INORGANIC ANIONS. A REVIEW 47 1 TABLE I STRUCTURES OF ANTHRAQUINONES Carminic acid OH CO( CHOH)*CH, OH OH COOH OH H CH3 Quinizarin OH H H OH H H H H Name \ Alizarin Red S H S03Na OH OH H H H H 1-Amino-4-hydroxyanthraquinone was the first anthraquinone tested for the qualitative fluorimetric determination of boron.The complex shows an intense orange - brown fluor-escence in daylight in concentrated sulphuric A method for the determination of boron with carminic acid in buffered neutral solution has been described,33 with a standard deviation of 0.03 pg ml-1. Initially the method involves the use of cochineal a preparation obtained from the dried female insect Coccus cacti L. and of its chief active constituent carminic acid.34 H01me~~ carried out a systematic investigation of complex formation in concentrated sulphuric acid between boric acid and a series of hydroxyanthraquinones (1,4-dihydroxy-, 1,5-dihydroxy- 1 ,&dihydroxy- 1,2,3-trihydroxy- 1,2,4-trihydroxy- and 1,2,3,5,6,7-hexahydr-oxyanthraquinone) . He found that quinizarin (1,4-dihydroxyanthraquinone) was the only reagent to produce a fluorescent complex and he described the determination of boron with this reagent.Alizarin Red S changes its yellow fluorescence to pinkish red in the presence of b ~ r o n . ~ ~ ~ ~ A chelate ester with a six-membered ring is formed in the reaction. Boron can be determined with this reagent in the presence of a 1 000-fold excess of most cations and anions; only iodides, chlorates antimony and iron interfere. The interference of iodides is eliminated by the addition of powdered silver sulphate that of chlorates by the introduction of 30% formalde-hyde solution that of antimony by chlorine water and that of iron by reduction with tin(1I) chloride powder. Hydroxyjavones These reagents can form binary or ternary complexes with boron.The hydroxyflavones used are shown in Table 11. In this section only the binary complexes that appear in the bibliography as such will be cited and later when ternary complexes are described both will be discussed. Murata and Y a r n a u ~ h i ~ ~ described the determination of boron with morin based on the Taubock test.39 A yellowish green fluorescence is produced in acetone solution. The authors verified that the intensity of the fluorescence increased in the presence of organic acids such as oxalic malonic succinic and phthalic acid. This method is applicable to the analysis of natural waters without the separation of boron 472 GOMEZ-HENS AND VALCARCEL SPECTROFLUORIMETRIC TABLE I1 STRUCTURES OF HYDROXYFLAVONES Analyst VoZ. 107 - Flavonol H OH H H H H H H H H Name Quercetin Kaempferol H H OH OH OH H OH OH OH OH A H H H H H H OH OH H H I Morin OH OH H OH OH H H H OH H Ketones determination of boron.Benzoin (V) is a fluorimetric reagent widely used for the q~alitative~O-~~ and q~antitative~~-50 v Parker and Barnes44 carried out some experiments with spectrofluorimeters and filter fluorimeters using the reaction of boron with benzoin. They showed that oxygen should be removed from this system and although the maximum excitation is at 365 nm they recom-mended 405 nm in order to decrease the decomposition of the reagent. In a later ~ a p e r ~ 5 these authors applied the method to the determination of boron in silicon (limit of detection about 0.03 p.p.m.) in sea water (with a precision of better than 2%) and in steel (limit of detection about 1 p.p.m.).White and Hoffman46 showed that it is desirable to use a glycine buffer of pH 12.8 because the intensity readings are more stable than those obtained when using the original procedure in which sodium hydroxide was used. Elliot and R a d l e ~ ~ ~ also studied the deactivating effects of oxygen in this system and investigated other solvents in the hope of increasing the sensitivity of the reaction. They showed that the intensity of fluorescence when formamide is used is stronger than that when ethanol is used. They discussed the possible relationship between the dielectric constant of the solvent and the fluorescence intensity of the system. Other workers have applied this method to the determination of boron in raw material with iron49 and in soils.5o Boric acid forms a highly sensitive luminescent complex with dibenzoylmethane (VI) in concentrated sulphuric acid,51 which is proposed for the trace determination of boric acid.V May 1982 DETERMINATION OF INORGANIC ANIONS. A REVIEW 473 The limit of detection is 0.5 ng ml-l. This method has been applied to the determination of 10-7-10-6% of boron in antimony(II1) chloride and oxide and antimony(V) chloride.52 Neelakantam and Rao53 proposed the determination of boric acid with resacetophenone (VII). In concentrated sulphuric acid a brilliant blue fluorescence is obtained with trace amounts of boric acid under ultraviolet radiation. A disadvantage of the method is the necessity of working under filtered ultraviolet radiation.In a later paper,54 various substituted resaceto-phenones were investigated in an attempt to find a material that would emit fluorescence in the visible range. No shift from the ultraviolet to the visible region was found i.e. an increase in relative molecular mass did not bring about any shift of the fluorescence into the visible region. In the same paper methods of overcoming interferences were discussed. The re-placement of concentrated sulphuric acid by syrupy phosphoric acid rendered the method more sensitive,55 and also obviated the interference of some ions such as bromide iodide and nitrate. VI I 2,4-Dihydroxybenzophenone f o m s a fluorescent complex with boric acid in sulphuric acid Maximum fluorescence intensity is obtained after 10 h.Under these conditions the blanks give a relatively high fluorescence because the reagent suffers partial oxidation and is converted into fluorescent products. This is avoided by working at 70 “C where equilibrium is obtained in less than 20 min. An essential factor is the purity of the acid utilised because if the sulphuric acid has only average purity an increase in the photodecomposition of the blanks is observed and the spectral characteristics of the complex are modified. Kristalev and Shevchenko57 carried out a comparative study of methods for the determination of boron with 2,4-dihydroxybenzophenone and resacetophenone. They deduced that the former method is more sensitive but the fluorescence development is slow the intensity de-pending on the ultraviolet irradiation time and the intensity decreasing in the presence of phosphate.The second complex forms almost instantaneously and is resistant to ultraviolet irradiation. Marcantonatos et aZ.58 studied the reactions of boric acid with nine substituted 2-hydroxy-benzophenones (VIII) in concentrated sulphuric acid 2-hydroxy-4-methoxy-4’-chlorobenzo-phenone 2-hydroxy-4-methoxy-4’-methylbenzophenone 2,2’,4,4’-tetrahydroxybenzophen-one 2,2’-dihydroxy-4,4’-dimethoxybenzophenone 2,2’-dihydroxy-4-methoxybenzophenone, 2,2’-dihydroxy-4-n-octyloxybenzophenone 2-hydroxy-5-chlorobenzophenone 2-hydroxy-5-methylbenzophenone and 2,4,4’-trihydroxybenzophenone. ,All of these reagents form fluor-escent complexes with boric acid. Their excitation spectra indicate that these complexes are similar in structure and the fluorescence spectra show that the composition and intensity of fluor-escent light depend on the electronic nature of the various substituents of the complexing agents.All of these reagents can be used for the determination of submicrogram amounts of boron but 2-hydroxy-4-methoxy-4’-chlorobenzophenone is the most sensitive. In a later paper,S9 these workers thoroughly studied the influence of some properties of the medium on the fluorescence of the boric acid - 2-hydroxy-4-methoxy-4’-chlorobenzophenone complex. When concentrated sulphuric acid is replaced by glacial acetic - concentrated sulphuric acid the intensity of fluorescence increases considerably. The method has been with a stoicheiometry of 1 1.Vll 474 GOMEZ-HENS AND VALCARCEL SPECTROFLUORKMETRIC Analyst VoZ. I07 applied to the determination of trace amounts of boron in analytical-reagent grade sodium hydroxide,60 steels,61 plants,62 waterss3 and b l ~ ~ d . ~ ~ ~ ~ ~ developed an auto-mated method based on this reaction for the determination of boron in natural waters, detergents and sewage effluents. Afghan et Other reagents Shcherbov and K0rzheva6~@ suggested a method for the determination of boron with phenylfluorone (IX) in aqueous alkaline medium where the complex formed has a dark blue fluorescence.69 On standing the fluorescence intensity in solutions containing the reagent changes; in the blank solution it decreases but in the solution containing boron it becomes higher ; after a 24-h period 1 pg of boron can be detected in 1 ml.This fluorescence persists for 2-3 days. Many cations interfere in the reaction by quenching of the fluorescence. HoaoaoH HO 0 IX Nazarenko and Vinko~etskaya7~ studied sixteen 2,3,7-trihydroxy-6-fluorones with sub-stituents in the 9-position as fluorescent reagents for boron. These reagents give fluorescence reactions of low sensitivity in neutral and weakly alkaline media with boron. The most sensitive reagent is phenylfluorone. Boron forms 1 1 complexes with trihydroxyfluorones by replacing the proton in the reagent molecule. A method for the determination of boron with Thoron I (X) [2-(2-hydroxy-3,6-disulpho-l-naphthylazo) benzenearsonic acid] has been proposed.71 It is slightly less sensitive than the method with benzoin but is simpler and more precise and does not need special precautions.This method has been used to determine boron in high-purity silicon tetra~hloride.7~ Boric acid forms a fluorescent complex with salicylic acid.73 Podchainova et aZ.74 verified that decreasing the temperature from 20 to -196 "C causes the fluorescence intensity to increase more than 10-fold. They also studied the reaction of boron with acetylsalicylic a ~ i d . 7 ~ Chromotropic acid (4,5-dihydroxy-2,7-naphthalenedisulphonic acid)76 has been proposed as a fluorimetric reagent for boron. This method has a coefficient of variation of 2.9% for 0.5 mM boric acid and 5.7% for 0.05 mM boric acid. The addition of masking agents improves the selectivity of the method. Formation of Ternary Complexes Hydroxyflavones - oxalic acid Pszonicki and c~-workeSSP~-*~ have studied extensively the determination of boron with morin quercetin and kaempferol (Table II) in the presence of oxalic acid by formation of ternary complexes May 1982 DETERMINATION OF INORGANIC ANIONS.A REVIEW 475 The fluorescence of the boric acid - morin - oxalic acid complex is strongly quenched by alkali metals. This is probably caused by a reaction of the alkali metals with the 4’-carbonyl group of morin and the resulting formation of compounds of the phenolate type. This reaction eliminates the conjugated double bonds that provide the fluorescence emission from the complex molecule. Alkali metals can be separated from boron with an ion-exchange resin. In another paper,s2 they described the formation and properties of two types of complex a binary flavone - boric acid complex and a ternary flavone - boric acid - oxalic acid complex, in anhydrous acetic acid.The flavones studied were morin and quercetin and the proposed structural formulae are XI XI I Xlll XIV where XI and XI1 are the binary and ternary complexes of morin respectively and XI11 and XIV are the binary and the ternary complexes of quercetin respectively. All of these compounds have a flavone - boric acid stoicheiometry of 1 1 except for the binary quercetin -boric acid complex which has a ratio of 2 1. The ternary complexes in acetic acid decom-pose to the binary complexes. The presence of about 1 yo of oxalic acid in the solution prevents degradation of the ternary complexes and improves their solubility considerably.Degraded ternary complexes can be re-formed by addition of an excess of oxalic acid. The fluorescence spectrum of the binary complex coincides exactly with that of the ternary complex but the intensity is about ten times lower. The fluorescence maximum for all of the complexes occurs at 505 nm. The preparation of these compounds is based on the procedures of Hor-hammer and Hansels3 and Hansel and S t r a s ~ e r . ~ ~ Calcein Blue - zirconium Hems et aLS5 studied the determination of zirconium with Calcein Blue (XV) and verified the positive interference that fluoride and sulphate ions produced on the fluorescence intensity of the complex. Based on this fact Har and Westa6 proposed two methods for the determina-tion of both anions.All spectrofluorimetric methods for the determination of fluorides, excluding this one are based on the ability of fluoride to abstract cations from strongl 476 GOMEZ-HENS AND VALCARCEL SPECTROFLUORIMETRIC Analyst VOZ. I07 CH3 -02CH2C H02CH2C k-CH2-& HO 0 xv fluorescing complexes thus liberating the free reagent. Such fluorescence quenching methods tend to be unselective. The increase in the fluorescence intensity of the binary zirconium -Calcein Blue complex is due to the formation of a ternary fluorine - zirconium - Calcein Blue complex which has a stoicheiometry of 1 1 1.86 This method is rapid and reproducible and has a precision of &3% near the middle range of the calibration graphs. The sulphate reaction87 is much weaker than the fluoride reaction and it is necessary to use a considerable (100-1000 molar ratio) amount of sulphate ion to obtain a linear calibration graph.However, the authors suggest the probable existence of a 1 1 1 ternary complex. Benzoin - mannitol A method probably based on the formation of a ternary complex has been developed for the determination of silicon with benzoin and mannitol in a solution containing formamide and sodium hydroxide.a8 Sorbitol behaves similarly to mannitol but the fluorescence output for a given concentration of silicon is lower. Methods Based on Formation of Ion-association Complexes The methodology is based on the formation of an ionic association that has fluorescent properties and usually is extracted in organic solvents.What will be considered is the forma-tion of binary species and the formation of the ion-association ternary complexes defined by Westsg as the association of a charged binary complex usually a dyestuff with an ion of the opposite charge. Ion-association Binary Complexes The only fluorimetric method reported for the determination of perchlorate ions is based on the extraction of the ion pair formed between this anion and amiloride [3,5-diamino-N-(aminoiminomethyl)-6-chloropyrazinecarboxamide]g0 at pH 4 into 4-methylpentan-2-one. The fluorescence reaction of nitrite with Ethylrhodamine S (XVI) was used to determine nitrite.91 The authors did not explain the reaction but taking into account the redox character of nitrite it could be a redox reaction. The compound formed is extracted into benzene and diluted with acetone.CH~CH~COOC~HS XVI Safranine T cation (L+) (XVII) has been used for the determination of chromium(VI)Q2 by the formation of an ion-association complex at pH 1 with a Cr,072- to Lf ratio of 1:2. XVl May 1982 DETERMINATION OF INORGANIC ANIONS. A REVIEW 477 In the presence of chloride a more intensely fluorescent compound is formed probably con-taining 2L+ Cr20,2- and C1-. The addition of methanol and acetone increases the fluorescence of the ion association. The method has been developed for the determination of chromium(V1) in sodium chloride. Ion-association Ternary Complexes a basic dye cation that generally belongs to the family of the rhodamines (Table 111). These methods are based on the formation of an anionic binary complex associated with TABLE I11 STRUCTURES OF RHODAMINE DYES Name A f -I Substituent Rhodamine B Butylrhodamine B Rhodamine 6G C2H5 C2H5 C2H5 C2H5 H H H C * H 5 C2H5 C2H5 C2H5 H H C 4 H 9 Haddadg3 published an extensive review on the application of ternary complexes to spectro-fluorime t ric analysis.Several rhodamines (Rhodamine S Rhodamine 6G and Butylrhodamine B) were compared as reagents for the determination of borong4 by measurement of the luminescence of their compounds with BF4- in benzene solution. The addition of acetone to the benzene extract increased the luminescence considerably in de-terminations with Butylrhodamine B and the addition of acetone to the aqueous phase before the extraction with benzene increased the intensity of luminescence of the extract in determinations with Rhodamine 6G.In a later paper Bablgo et aZ.95 used the same method with Butylrhodamine B but having previously removed the cations with an ion-exchange resin in the acidic form. Boron has been determined with salicylic acid and Rhodamine 6G.96197 The excess of salicylic acid was removed after evaporating the solution to dryness by complexing it with iron(II1). The data were used for the development of a luminescence method for the determination of boron in waters rocks soils, coals and plants.98 Phosphorus can be determined as orthophosphate by the formation of the ion-association complex of molybdophosphate with the basic dyestuff Rhodamine B.99 After the extraction of excess of dye reagent into chloroform the Rhodamine B - molybdophosphate is extracted into chloroform - butanol (4 + 1).A study of the stoicheiometry in the ion-association complex revealed a combining ratio of 3 mol of Rhodamine B to 1 mol of molybdophosphate. This is in accordance with the formation of an uncharged complex of the type [RhB+],-[ PMo3-1. The orthophosphate ion is also determined by precipitation of quinine molybdophosphate in 0.5 M sulphuric acid. The excess of the quinine reagent is removed by washing the pre-cipitate with 0.5 M sulphuric acid and the complex is dissolved in the solvent mixture acetone -Butylrhodamine B was the best reagent. The complex of boron was extracted into benzene 478 GOMEZ-HENS AND VALCARCEL SPECTROFLUORIMETRIC Analyst Vol.I07 0.5 M sulphuric acid (9 + 1).lo0 The authors suggested that the precipitate corresponds to the composition (C,oH,,O,N?H,) ~(PMO~~O~O), similar to that of quinine - molybdovanado-phosphate as proposed by Ripau and Suteu.lol Methods Based on Substitution Reactions The methods included in this section are those based on the reaction between the anion and a cation that initially formed a chelate with an organic reagent. The methods in which the cation forms a fluorescent chelate and where the anion inhibits its fluorescence have been grouped as quenching reactions. Fluorescence reactions are those methods in which the initial chelate is non-fluorescent and the substitution reaction releases the organic reagent, which is either fluorescent or reacts with other species to form a fluorescent compound.Each group has been systematised according to the cation involved in the substitution reaction. Quenching Reactions By aluminium Fluorescent aluminium chelates have been widely used to determine several anions indirectly, especially fluoride. Bishop1o2 studied the influence of anions on the morin test for aluminium gallium beryllium and zinc and proposed several tests for the detection of fluoride oxalate citrate phosphate, tartrate and vanadate. The quantitative determination of fluorides with the aluminium -morin system has been widely studied.lo3-lo5 Willard and Hortonlo4 used this system among others. They obtained a curved calibration graph of fluorescence versus fluoride concentration because more than one fluoride complex is formed by aluminium ions.As the fluoride con-centrations increase AlF2+ AlF,+ AlF, AlF4- and perhaps AlF52- and AlF63- complexes are formed consecutively. In this series as more and more fluoride is required to complex a certain amount of aluminium the rapidity of the decrease in fluorescence decreases with a consequent loss in sensitivity and precision for large amounts of fluoride. Fortunately the sensitivity is highest a t the lowest levels of fluoride where other methods have lower accuracy. To avoid the numerous interferences the authors advise the separation of the fluoride by Willard and Winter’s methodlo6 for liquid samples or as hydrogen fluoride by pyrohydroly~is~~~ for heavy metal fluorides. Bournan105 used Willard and Horton’s method to determine fluoride but he changed the conditions to increase the sensitivity.He determined fluorides in 0.25 ml of water with an. accuracy of *0.02 pg ml-l. Land and Edmondslw have studied fluorescence quenching by phosphate on aluminium -morin aluminium - 3-hydroxyflavone gallium - morin gallium - 3-hydroxyflavone gallium -quercetin zirconium - morin and zirconium - 3-hydroxyflavone systems. They have found that only the first of these is suitable for determining the phosphate ion. The percentage of alcohol affects the aluminium - morin system considerably as a large percentage causes non-linearity in fluorescence quenching. This method suffers from many interferences by cations and anions which led to the suggestion of a method for isolating the phosphate ion.Guyon and Shultslog also studied this system and applied it to the determination of phosphate in well and pond waters. The interfering fluoride ions are removed by boiling the slightly acidic sample and the cationic interferences by precipitation with hydroxide ions. A method for determining fluoride has been proposed with the aluminium - quinolin-8-01 (oxine) system.104 This system was studied by Gentry and SherringtonllO in chloroform solution. The presence of fluoride in the aqueous phase before extraction removes some of the aluminium as a complex ion reducing the amount present as quinolin-8-olate and extract-able with chloroform. The necessity for extraction adversely affects the precision of this method. Powell and Saylorlll developed two methods for the determination of trace amounts of fluorides based on the fact that the intensity of fluorescence in the compounds formed in the reaction of aluminium chloride with two dihydroxyazo dyes Eriochrome Red B (sodium salt of 4-~-sulphonaphth-2-ol-a-azo-1-phenyl-3-methyl-5-hydroxypyrazole) (XVIII) and Super-chrome Garnet Y (sodium salt of 5-sulpho-2-hydroxybenzeneazoresorcinol) (XIX) is decreased on the addition of fluoride.These methods were tested by analysing solutions of pure sodium fluoride both before and after a Willard - Winter distillation. The ions that are often present after distillation such as sulphate and phosphate do not interfere seriously. The aluminium - morin complex is the most commonly utilised May 1982 DETERMINATION OF INORGANIC ANIONS. A REVIEW 479 0 Sb3Na XI x XVlll Another fluorescent aluminium chelate used to determine fluoride is the aluminium - 1-(2-pyridylazo)naphth-2-01 (PAN) system.l12 Two procedures have been described one for high sensitivity and the other for a wider range but with poorer sensitivity.Finally Bourstyn113 suggested that the fluorescence quenching produced on the aluminium - Pontachrome Blue Black R (2,2’-dihydroxy- 1 1’-azonaphthalene-4-sulphonic acid) system could be used to characterise this anion but it has not yet been investigated. By thorium The thorium - morin system has been used to determine fluorides in biological samples.ll* The values obtained for serum fluoride with this reagent after diffusion at room temperature agree with those obtained with the fluoride electrode and with those predicted by renal clearance of radioactive fluoride.This thorium - morin system has been amply utilised to determine sulphate. Fletcher and Milkey1153116 studied the thorium - morin system in a dilute acid medium and noted the serious interference of sulphate in the formation of the complex caused by the formation of sulphate complexes with thorium. Based on these interactions a determination of sulphate has been developed by Guyon and Lorah.l17 This method is more sensitive than most existing methods, is rapid manipulatively simple and adaptable to the determination of large numbers of samples. Vlasov et aZ.11S9119 have used this method to determine sulphate in weakly mineralised waters and Nasu120 to analyse snow and river waters. Nasu et aZ.121 have also studied the determination of sulphate with the thorium - flavanol system.They have used it to analyse lake river and mine waters and snow. By magnesium Fluoride ions cause fluorescence quenching on the magnesium - quinolin-8-01 system. This is used to measure air pollution with a fluoride analyser in which air is drawn past a moving 35-mm tape freshly impregnated with magnesium - q u i n o l i n - 8 - 0 1 . ~ ~ ~ ~ ~ ~ ~ Variations in the fluorescence are recorded continuously for the assay of fluoride. Ivie124 and Thompson et aZ.125 also designed a simplified fluoride analyser with the same system. A method for determining urinary phosphate with the magnesium - 3-hydroxy-3‘4’-dimethoxyflavone system has been proposed.126 Phosphate is previously extracted from the sample as molybdophosphoric acid with isobutyl alcohol.By mercury Di- and tetra(acetoxymercuri)fluorescein in alkaline solution give a green fluorescence that is quenched by compounds containing the sulphydryl group. This reaction called the Wronski reaction has not been investigated extensively but substitution of the acetoxy group by the sulphydryl group may occur. The Wronski reaction could also be considered as a complex formation reaction. Grunert et aZ.127 used di( acetoxymercuri) fluorescein to determine sulphide ions and Axelrod et aZ.12s applied this method to determine hydrogen sulphide in the atmosphere. The method proposed by Hardwick et aZ.129 for determining hydrogen sulphide in air with this reagent has been very controversial.~3’F-~33 Using 2’,7’-di( acetoxymercuri)fluorescein two methods for the determination of cyanide and iodide have been proposed.13 480 GOMEZ-HENS AND VALCARCEL SPECTROFLUORIMETRIC Analyst VOZ.107 Y a n y s h e ~ a l ~ ~ determined sulphur in red phosphorus with tetra(acet0xymercuri) fluorescein. The sulphur is oxidised to sulphate with nitric acid the sulphate is reduced to hydrogen sulphide with Cr2+ and the sulphide is determined by fluorescence quenching of the reagent. This method is based on the titration with this reagent proposed by Wronski.l36 With the same reagent Babko et a1.13' determined S S2- and S2C12 in chloroform carbon tetrachloride and titanium(1V) chloride and sulphide was determined by Shafran et in trichlorosilane and water and by S a m o i l ~ v l ~ ~ in ultra-high purity substances.This reagent has also been used to determine hydrogen sulphide and hydrogen cyanide by using indicator tubes140 and for the determination of S2032- and CN- in a solution containing biuret.141 Recently Mori et al.142 proposed a quenching method for the determination of the sulphide ion with the 3,4,5,6-tetrachlorofluorescein - mercury compound. By other cations Guyon et al.143 and Britton and G ~ y o n l ~ ~ described methods for determining fluorides and oxalates respectively using the zirconium - flavonol complex studied previously by Alford et a1.145 The tin - flavonol system has been proposed as a rapid method for determining phosphate in well and pond ~ater.10~ A special substitution method for the determination of iodide is based on its inhibitory action on the fluorescence of uranyl acetate.146 Previously JTolmarla7 studied this effect qualitatively with several ions.Both methods are selective simple and sensitive. Fluorescence Reactions By palladium A rapid and sensitive method has been developed for the determination of microgram amounts of sulphide and cyanide.148 This method depends on the demasking of quinolin-8-01-5-sulphonic acid by cyanide or sulphide from the non-fluorescent potassium bis(5-su1phoxino)-palladium( 11). The liberated quinolin-8-ol-5-sulphonic acid then coordinates with the mag-nesium ion present to form a fluorescent chelate which is a measure of the amount of cyanide or sulphide present. The reactions are shown below. S03K S03K I 1 + 4CN- 4 0-Cyanide can also be determined by a method149 based on the liberation of piazselenol The organic reagent [naphtho(2,3-c) (1,2,5)selenadiazole] (L) from the Pd2L,Cl4 ~omp1ex.l~~ is then extracted into hexane and its fluorescence is measured May 1982 DETERMINATION OF INORGANIC ANIONS.A REVIEW 481 By copper 2-(o-Hydroxyphenyl) benzoxazole (HPB) exhibits a bright green fluorescence in acetone solution that is attenuated in the presence of copper(I1) ions because a non-fluorescent chelate (XX) is formed.151 xx Vernon and Whitham15 proposed a method for determining sulphide or cyanide ions based on the reaction of one of these anions with an excess of copper addition of HPB which reacts with excess of copper and measurement of the fluorescence intensity of free HPB.In this method the order of addition is important because if copper(I1) ions and HPB interact a large amount of anion is required to regenerate the fluorescence of the reagent. Although the method is based on the fluorescence quenching that copper produces on HPB we have placed it in this section because the slope of the calibration graph is positive because when the amount of anion increases there is less copper to react with HPB. Ryan and HolzbecherZ3 proposed a method for determining cyanide based on this ligand-exchange reaction. Cyanide displaces calcein from its non-fluorescent complex with copper( 11). By mercury (11) - 2,2’-pyridylbenzimidazole. fluorescent and the free reagent is very fluorescent. Bark and Rixon153 described the determination of trace amounts of sulphide with mercury-This chelate with the probable structure XXI is non-If the sulphide ion is added to the system containing the mercury(I1) complex mercury( 11) sulphide is formed and an equivalent amount of the fluorescent organic ligand is released.Thus the fluorescence intensity of the system is increased. When a large excess of acetate buffer is added to the system some of the chloride may be replaced by acetate and the authors suggested the following reactions for release of the ligand : HgLC1 + H,S + L + HgS + 2HC1 HgLAc + H,S + L + HgS + 2HAc where L represents ligand and Ac represent CH,COO-. By other cations Thorium forms a light red non-fluorescent complex with salicylfluorone [9-(o-hydroxy-phenyl) trihydroxyfluorone] in a weakly acidic medium whereas free salicylfluorone in ultra-violet light gives a clear greenish yellow illumination.If thorium is added to a solution o 482 GOMEZ-HENS AND VALCARCEL SPECTROFLUORIMETRIC Analyst VoZ. I07 sulphate followed by the reagent part of the thorium becomes bound in the sulphate complex and part is liberated. The sensitivity of the reaction depends on the ratio of thorium to salicylfluorone and it increases when the concentration of thorium exceeds that of salicyl-fluorone. Two methods have been proposed for determining sulphate in germanium(1V) oxide15* and in distilled water155 based on these reactions. A special and indirect method for the determination of silicon consists in the formation of molybdosilicic acid extraction with isoamyl alcohol re-extraction with ammonia and de-termination of molybdenum by the formation of the molybdenum - carminic acid complex.l56 This method is used for the determination of silicon in hydrofluoric acid ammonia sodium hydrogen carbonate and ammonium molybdate.Methods Based on Enzymatic Reactions A selective method for determining inorganic phosphate is based on a series of three enzymic reactions at neutral pH.l57 Glycogen phosphorylase is used to catalyse the reaction between inorganic phosphorus (Pi) and glycogen forming glucose-1-phosphate which with phosphogluco-mutase is converted into glucose-6-phosphate. Finally with glucose-6-phosphate dehydro-genase and the addition of NADP 6-P-gluconolactone and NADPH are formed in proportion to the inorganic phosphate present : glycogen + Pi -+ glucose-1-P glucose-1-P -+ glucose-6-P glucose-6-P + NADP -+ 6-P-gluconolactone + NADPH, The NADPH formed is determined by measuring its fluorescence.This method is very sensitive because in terms of amount there is no real sensitivity limit as the NADPH formed can be measured by enzymic cycling. In terms of concentration the sensitivity is limited mainly by the degree to which phosphate can be removed from the reagents. As the analytical reaction takes place at neutrality inorganic phosphate can be measured in the presence of very unstable organic phosphate. Two methods have been proposed for the determination of cyanide based on its inhibitory action over two enzymic systems. The hydrolysis of the non-fluorescent indoxyl acetate (XXII) measures the enzymic activity of hyaluronidase through the formation of the highly fluorescent indigo white (XXIV).15* H XXll OH OH H XXI I I Cvanide and other ions inhibit the enzvmatic activity of H H XXlV hyaluronidase and their concentra-tio& can be determined by recording their effect on this eniymatic activity.into the highly fluorescent 2,2’-dihydroxy-3,3’-dimethoxybiphenyl-5,5’-diacetic acid: Using peroxidase non-fluorescent homovanillic acid is converted by hydrogen peroxide CHPCOOH CH2COOH CHpCOOH OH OH OH Cyanide sulphide dichromate sulphite and several cations can be determined by their inhibitory action over this enzymi May 1982 DETERMINATION OF INORGANIC ANIONS. A REVIEW 483 Discussion Borate A large number of fluorimetric reactions are known for the determination of borate anion.Some of them involve its previous distillation as methylborateg5s80 to isolate it from interfering species. In spite of the fact that benzoin is a widely used fluorimetric reagent for the determination of boron special precautions must be taken with this method as benzoin in alkaline solution is oxidised by the oxygen of the air and nitrogen must be bubbled through the solution.44 Also benzoin undergoes photodecomposition when exposed to radiation. 2-Hydroxy-4-methoxy-4’-chlorobenzophenone is a sensitive fluorimetric reagent for borate and has been applied satisfactorily in the determination of this anion in several samples. Monier et aZ.62 studied the action of 41 ions on the fluorescence of the complex and none interfered in the determination of borate.The fluoride ion interfered only at ratios of fluorine to boron of 100 1 (m/m) or greater. The method using diben~oylrnethane~~15~ (0.5 ng ml-l) quercetins1ta2 (0.3 ng ml-l) or 2-hydroxy-4-methoxy-4’-chlorobenzophenone58 (0.4 ng ml-l) are the most sensitive. Cyanide The reactions of cyanide with $-benzoquinonel2 and with quinone monoxime benzenesulphonate esterl3~l4 are highly selective. These reagents react specifically with cyanide. Other anions such as sulphide and thiocyanate which interfere in most tests for cyanide do not interfere in these determinations. The better sensitivity of fluorimetric methods versus colorimetric methods can be observed in the determination of cyanide with quinoline-8-ol-5-sulphonic acid.148 The colorimetric method is sensitive to 1 pg ml-1 of cyanide whereas the sensitivity of the fluorimetric method is 0.02 pg ml-l of cyanide.Oxalate similar sensitivities but the most selective is that using resorcinol.8 Fluoride All of the fluorimetric methods for determining fluoride except that based on the formation of a ternary fluorine - zirconium - Calcein Blue complex,86 are substitution methods. These are generally non-selective because they are fluorescence quenching methods and other complexing anions tend to interfere. Thus the method with Calcein Blue and zirconium is the most selective because of the common anions only phosphate interferes seriously at 5-fold excess and very few cations interfere. This method is also rapid and provides very high sensitivity for the determination of trace amounts of fluoride in aqueous solution down to 10 parts per lo9 (p.p.b.).The other methods for the fluorimetric determination of fluoride are also highly sensitive. For example the method with zirconium(1V) and flavonollg3 can be applied to the determination of fluoride in the range 2-100 p.p.b. Iodide None of them is specific for iodide but they have high sensitivity especially the method using cerium(IV)15 (6-25 p.p.b.). Also 2,7-di(acetoxymercuri)fluorescein~34 is a sensitive fluorimetric reagent for iodide (35400 p.p.b.) but the AA of the Stokes shift is not favourable and the method cannot be used with filter fluorimeters. Most of these methods for the determination of borate are highly sensitive.This anion has mainly been determined by redox and substitution reactions. There are few fluorimetric methods for the determination of oxalate. These methods have There are few fluorimetric methods for the determination of this anion. Nitrite The ability to determine the nitrite ion at low levels is important because this anion is commonly added to processed meats and may lead to the formation of carcinogenic nitros-amines in the human body. Fluorimetry has provided a means for the determination of this anion in the low nanogram range 484 GOMEZ-HENS AND VALCARCEL SPECTROFLUORIMETRIC Analyst VoZ. I07 The method using p-chloroaniline and 2,6-diaminopyridine6 is highly sensitive (limit of detection 2 p.p.b.) and apparently selective as the authors did not investigate the effect of di-verse ions on the method.They consider that interferences can be expected from those ions which either are not compatible with the nitrite ion or can effect the diazotisation and coupling reactions. 2,3-Diamin~naphthalene~ is also a sensitive fluorimetric reagent for nitrite (0-850 p.p.b.) but all these methods have the disadvantage of being complicated as they rely on solvent extraction. The method developed with 5-aminofluorescein is simple and is sensitive to 0.05 p.p.b. Nitrate All of the fluorimetric methods for determining nitrate ion are based on redox reactions. These methods are not selective but they can be applied to the determination of parts per billion levels of nitrate. The method with 2,2’-dihydroxy-4,4’-dimethoxybenzophenone~ is selective as only chloride, sulphide and fulvic acid can interfere but the authors investigated the removal of these interferences.In this method other forms of nitrogen such as nitrite or organic nitrogen compounds do not react; hence this method can be used to determine nitrate directly without any subtraction of background due to other forms of nitrogen. The nitrite ion interferes in other fluorimetric methods for determining nitrate. Phosphate Several types of method for the determination of orthophosphate exploit the high sensitivity of fluorimetric techniques. The ability of phosphate to inhibit the fluorescence of chelates led to the investigation of various metal - chelate systems for maximum sensitivity in the detection of trace amounts of phosphate.Several metal chelates of aluminium gallium and zirconium with morin 3-hydroxyflavone and quercetin have been examined but none proved as satisfactory as aluminium - morin for the determination of phosphate. Strongly com-plexing coloured and metallic ions have a detrimental effect on this method. For the technique to be specific phosphate must be separated from a number of cations and anions that interfere in the fluorimetric analysis. A sensitive and simple method is that using thiamine2*22 but several ions such as silicate and sulphide interfere. Oxidising agents before the formation of molybdophosphate can be destroyed by treatment with sulphite; the excess of sulphite must be removed by heating before addition of molybdate. The enzymatic method proposed by Shulz et aZ.15’ with glycogen is more specific but the treatment is too slow.Sulphide The extreme toxicity of hydrogen sulphide caused by the great ability of the sulphide ion to co-ordinate with many metals in the human metabolism led to the development of sensitive fluorimetric methods for the determination of trace amounts of sulphide in atmospheres and effluents. These methods except for two are based on substitution reactions in spite of the redox character of the sulphide ion. The sensitivity of these methods is extremely high; for example the method with di(acetoxymercuri)fluorescein127-~33 is sensitive to 1 p.p.b. and with the mercury(I1) - 2,2’-pyridylbenzimidazole system153 0.3 p.p.b. can be detected. None of the fluorimetric methods for determining sulphide is selective and often they are subject to interference from cyanide and thiocyanate ions.Sulphate Fluorimetric methods for determining sulphate are mainly based on the ability of this anion to react with thorium ion to liberate an organic reagent that initially forms a complex with thorium. These methods are subject to interference from ions such as phosphate and fluoride. The method using thorium - salicylfluorone154~155 is the most sensitive (0-2 pg) May 1982 DETERMINATION OF INORGANIC ANIONS. A REVIEW 485 Conclusions 1. This systematic study leads to the conclusion that approximately 70% of the fluorimetric methods for determining inorganic anions are based on reactions of appearance of fluorescence (Fig. 1). This refutes the general belief that most of these methods are based on phenomena of fluorescence quenching probably owing to the masking character of the anions.Fig. 1. Fluorescence methods for the determination of inorganic anions A, methods based on the appearance of fluorescence 67.5% ; and B methods based on fluorescence quenching 32.5%. 2. A study of the percentage of each type of the described methods shows that one third of these methods are based on substitution reactions. Approximately one quarter are based on redox reactions and one fifth on complex formation reactions. Methods based on the formation of ion-association complexes and on enzymatic reactions comprise less than 10% (Fig. 2). Fig. 2. Types of reactions used in the determination of inorganic anions by fluorescence methods A formation of complexes 2 1.7 % ; B redox reactions, 27.7%; C enzymatic reactions 4.8%; D, substitution reactions 37.4% ; and E, formation of ion-association complexes, 8.4% 486 GOMEZ-HENS AND VALCARCEL SPECTROFLUORIMETRIC Analyst VoZ.107 3. A statistical study of the proposed fluorimetric methods for the determination of anions shows that borate is the one that has been identified by most methods mainly by the forma-tion of complex reactions. Cyanide is determined equally by redox and substitution methods. Substitution methods are mainly used to determine fluoride and sulphide anions and redox reactions to determine nitrate and nitrite (Fig. 3). 4. From the analytical viewpoint the main advantage of these methods is their sensitivity.In many instances the applicable range is between 1 and 100 p.p.b. Generally the most sensitive methods are those based on substitution reactions. 5. In general the selectivity of these methods is not good although some methods are satisfactory . Methods based on fluorescence quenching are less selective than those using the appearance of fluorescence. Of the five types of methods substitution methods are the least selective. Generally redox and complex formation methods give the highest levels of sele ct ivi t y . 6. The accuracy of these methods is acceptable according to the concentration of the de-termined anions. 7. Perhaps the future of the fluorimetric determination of inorganic anions lies in the study and application of catalysed reactions in which fluorescent species are implicated.The asso-ciation of kinetic methods with fluorescence such as we have verified in the determination of cationic species gives a methodology of high sensitivity and remarkable selectivity. . . . . . . . . sio32- WI . . . . Others I I Fig. 3. Distribution of the types of reactions inorganic anions. Formation of com plexes Redox reactions Substitution reactions Formation of ion-association complexes Enzymatic reactions used in the determination of variou APPENDIX Summary of Spectrofluorimetric Methods for the Determination of Inorganic Abbreviations R = redox method; CF = complex formation method; IAC = ion-association method; En = enzymatic method; (Q) = fluorescence quenching method; (E) = extraction; emission wavelength.Type of Reagents method Reaction conditions Aex/Aem/nm Carminic acid CF p H 7 4761585 Quinizarin CF 91-96% H2SO4 3651595 Anion B02- . . Sensitivity 2.5 pg ml-l 0.04 x 10-4-0.8 x 1 0 -1 pg ml-1 0.2-0.8 ng ml-0.3 ng ml-l 0.05-0.5 pg Alizarin Red S Morin CF CF 0.002% H2S04 Oxalic acid + acetone + diethyl Oxalic acid + glacial acetic acid pH 12.8 (glycine buffer), Na2C0, H2S04 + diethyl ether Conc. H2S04 or syrupy phos-Conc. H,S04 Conc. H,S04 pH 9.5 Conc. H,SO, lO-l6% H,O H2S04 - acetic acid (2 + 3), Conc. H2S04 pH 6.7 (acetate buffer contain-ing masking agents) Optimum pH range 2-8 C,H from 0.1 N H,SO + 0.05 N NH4F C,H from 0.001 N HC1 ether or glacial acetic acid formamide phoric acid -196 "C 4251505 Quercetin Benzoin CF CF 4431505 3701480 4051483 3851410 3651 3651503 3861490 0.01-0.08 pg 0.5 ng ml-l 2.5-7.0 mg per 0.003 6-0.18 pg 0.00036-0.036 Dibenzoylmethane Resacetophenone 2,4-Dihydroxybenzophenone Hydroxy-2-methoxy-4-chloro-Phenylfluorone Thoron I Salicylic acid Acetylsalicylic acid Chromotropic acid Butylrhodamine + F-4'-benzophenone CF CF CF CF CF CF CF 1 pg ml-1 0.01-0.7 pg ml- 3651587 CF CF 3651410 3131380 0.01 pg ml-1 0.01-0.5 mg ml-3361590 0.01-0.5 pg per Rhodamine 6G + salicylic acid 3661440 0.001 pg Br- .. Fluorescein + H202 R ' Acetic anhydride 4401470 2 ng ml-l (Q) C10,- . . Amiloride hydrochloride IAC 4-Methylpentan-2-one from 3681410 0-50 pg per 20 (E) PH Anion Reagents CN- Nicotinamide + chloramine-T Pyridoxal p-Benzoquinone Quinone monoxime benzene-Cu(I1) + leucofluorescein H202 + luminol + Cu(I1) 2’,7’-Di( acetoxy mercuri) -Tetra (acetoxymercuri) -Quinolin-8-01-5-sulphonic acid sulphonate ester fluorescein + KI fluorescein Pd(I1) - piazselenol Cu(I1) + 2-(o-hydroxyphenyl)-benzoxazole Cu(I1) + calcein Hyaluronidase + indoxyl Homovanillic acid + H202 + acetate peroxidase C20,2- .Resorcinol Ce (IV) Zr(1V) + flavonol Cr2OV2- . . Safranine T APPEND IX-con t inued Type of method Reaction conditions hex/Xem/nm Sensitivity R R R R R R S S S (Q) S S S En En R (Q) (Q) R S (Q) IAC (E) KOH KHCO Corning 0.3-6 pg ml-l No. 59701 Corning Nos.4308, 3389 Treatment at pH 7.5 (phosphate 365/432 10-40 p~ pH 7.5 (phosphate buffer) 400/480 0.2-50 pg ml-Dimethyl sulphoxide 440/500 0.5 pg ml-l buffer) and measure at pH 10 dimethyl sulphoxide 4941515 0-100 P.P.b. <12 p.p.m. pH 8.3 (borate buffer) 4991519 3.59-8.59 pg 25 ml pH 5-8 515/ 0.01-0.10 pmol 3 ml pH 9.2 (glycine buffer) Corning No. 0.02 pg ml-I 59701 Corning Nos. 4308, 3389 3771520 25 OC pH 8 hexane M NaOH 355/439 488/500-575 pH 6.40 (McIlvaine buffer) 3951470 pH 8.5 (Tris buffer) Zn + HC1 490/530 Carbonate - hydrogen carbonate buffer H2S04 + OsO 365/460 2601350 pH 1.69 pH 1 (0.05 M H2S04 + 0.4 M 5151560 NaCll Dichloioethane + methanol + acetone 100 pg per 3 0-200 ng ml-l 10-250 p.p.b.0.20-6 pg ml-1-100 pg ml-8 pg per 100 8.8-44.0 pg per 0.5-10 pg per 10-80 ng ml-Anion Reagents F- . . Zr(1V) + Calcein Blue Al(II1) + morin Al(II1) + quinolin-8-01 Al(II1) + Superchrome Garnet Y Al(II1) + Eriochrome Red B Al(II1) + PAN Th(1V) + morin Mg(I1) + quinolin-8-01 Zr(1V) + flavonol I- . . Ce(V1) + As(II1) 2,7-Di(acetoxymercuri)-fluorescein Uranyl acetate NO,- . . 5-Aminofluorescein 2,3-Diaminonaphthalene 9-Chloroaniline + 2,6-diaminopyridine + ammoniacal copper(I1) sulphate solution Resorcinol APPEND IX-cont inued Type of method Reaction conditions Aex/Aem/nm pH 2.5 3501410 pH 4.9 (monochloroacetic acid 365/500 + glacial acetic acid + NaOH) 50% ethanol CHC1 from pH 4.7 Corning No. 58501530 pH 4.8 (acetic acid - sodium Corning No.Corning No. 3389 As above As above acetate buffer) 58601 HNO, HC1 or HBr 350-5451 590 Acidic medium 4201510 Hydrogen fluoride detector in 4201530 gases by continuous monitoring of quenching of a filter-paper sensitised with Mg(quino1in-8-01), pH 1.78 (H,SO,) 380-395/ 460 H W 4 2601530 pH 8.3 (borate buffer) 499/519 NaOH 3651520 0.5 M HCl 1.1 M NaOH 4901515 1,1’,2,2’-Tetrachloroethane 3641412 C,H from pH 5 (acetate buffer) 360/430 HClO, NH, 5461582 Sensitivity 0.9-6.0 pg per 0.2-35 pg per 0.5-20 pg per 0.2-100 pg per 2-100 P.P.b. 0.6-2.5 pg per 0.87-9.81 ng 2-20 p g per 100 5 x 10-9- 5 x 0-850 ng 25 ml 2 p.p.b. Up to 130 ng of Anion Reagents Benzidine Ethyrhodamine S NO,- .. 2,3-Diaminonaphthalene 2,2’-Dihydroxy-4,4’-Resorcinol dimethoxybenzophenone Disodium fluorescein PO,,- . . Molybdate + thiamine Molybdate + Rhodamine B Molybdate + quinine Al(II1) + morin Mg(I1) + 3-hydroxy-3’,4’-Sn(I1) + flavonol Glycogen dimethoxyflavone 9- . . Thiamine Di (acetoxymercuri) fluorescein APPEND IX-continued Type of method Reaction conditions Xe,/Aem/nm (Q) (Q) Tetra(acet0xymercuri) fluorescein S 5 mM HC1 90% ethanol C,H from 7 N H,SO, 5% KBr CuSO + NaOH + hydrazine sulphate 1,2-Dichloroethane 80% H,S04 NaCl + H2S04 heat for 1 h in 90% sulphuric acid boiling water NH, pH 8 (borax buffer) CHC1 - butanol (4 + 1) from 0.05 M H,SO in 90% acetone 50% ethanol apparent pH 4.50; 24% ethanol pH 5 (acetic acid - acetate) pH 10.7 (NH buffer) add dimethylformamide Ethanol + dimethylformamide 1 M HC1 3261387 3641412 3801445 5461582 4351485 3751440 3501575 3521445 3651510 4251508 445149’7 4051450 pH 6.6 (imidazole - HCl Corning No.Corning buffer) 58401 Sensitivity 0.25-1.25 pM 0.5 0.01-1.13 p.p. 5 pg-1.0 mg 1-6-70 ng of N 0.01 pg ml-1 5-100 p.p.b. 0.02-0.3 pg ml-0.01-0.6 p.p.m. < 1 pgml-1 0-12 pg per 10 > l O pg ml-1 0.02-0.1 mM 0.5-10 pg Nos. 4503, 3387 pH 7.7 (borate buffer) 3751440 <20 ng ml-l KMnO, 0.1 M NaOH 4991519 1-10 ng ml-I NaOH 3651 0.2 pg per 1 APPENDIX-continued Type of Anion Reagents method Reaction conditions 3,4,5,6-Tetrachloro- S pH 6.4-7.0 fluorescein - mercury Pd(I1) + quinolin-8-01-5-sulphonic acid Cu(I1) + 2-(o-hydroxyphenyl)-Hg(I1) - 2,2'-pyridyl-Homovanillic acid + H,O + benzoxazole benzimidazole peroxidase .. 5-Aminofluorescein + formaldehyde S042- . . Zr + Calcein Blue Th + morin Th + flavonol Th + salicylfluorone S,032- . . Tetra(acet0xymercuri)-S20s2- . . Leucofluorescein fluorescein . . Benzoin + mannitol Molybdate + carminic acid (Q) S pH 9.2 (glycine buffer) S 0.01 M NaOH S pH 6.2-7.3 En pH 8.5 (Tris buffer) R HC1 (Q) CF pH 1.9 s pH 2.3 S pH5-8 R CF Formamide + hydroxyl-ammonium chloride S pH 5.2 (acetate buffer) hen/hem/nm Sensitivity /550 0-40 pg per 10 Corning No. 0.2 pg ml-I 59701 Corning Nos. 4308 3389 355/439 1-100 ng ml-1 311/381 0.3-300 ng ml-0.3-3.2 pg ml-405-4601 0.02 pg ml-l 515 350/410 0.2-1 mg ml-l 3651500 390/470 515/ 0-20 pg per 25 <20 pg per 25 0.01-0.1 pg per 0-2 pg 440/470 5-10 p.p.m., (NH4)2S208 366/ 2-10 pg 475/505 0.003 pg ml-492 1.2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. G0MIi.Z-HENS AND VALCARCEL SPECTROFLUORIMETRIC Analyst VOZ. 107 References Williams W. J. “Handbook of Anion Determination,” Butterworths London 1979. Boltz D. F. “Colorimetric Determination of Nonmetals,” Volume 8 Wiley New York 1978.Axelrod H. D. and Engel N. A. Anal. Chem. 1975 47 922. Wiersma J. H. Anal. Lett. 1970 3 123. Sawicki C. R. Anal. Lett. 1971 4 761. Dombrowski L. J. and Pratt E. J. Anal. Chem. 1972 44 2268. Auerbach M. E. Eckert H. W. and Angell E. Cereal Chem. 1949 26 490. Zarembski P. M. and Hodgkinson A. Biochem. J . 1965 96 717. Afghan B. K. and Ryan J. F. Anal. Chem. 1975 47 2347; correction Anal. Chem. 1976 48, Nakamura M. Anal. Lett. 1980 13 771. Hanker J. S. Gamson R. M. and Klapper H. Anal. Chem. 1957 29 879. Guilbault G. G. and Kramer D. Anal. Chem. 1965 37 918. Guilbault G. G. and Kramer D. Anal. Chem. 1965 37 1395. Guilbault G. G. and Kramer D. US Pat. 3432 269 1969. Kirkbright G. F. West T. S. and Woodward C.Anal. Chim. Acta 1966 36 298. Bonavita M. Arch. Biochem. Biophys. 1960 88 366. Takanashi S. and Tamura Z. Chem. Pharm. Bull. 1970 18 1633. Morgan R. L. and Way J. L. J . Anal. Toxicol. 1980 4 78. Marcantonatos M. and Nawratil B. Anal. Chim. Acta 1976 82 377. Wachsmuth H. J . Pharm. Belg. 1950 5 300. Holzbecher J. and Ryan D. E. Anal. Chim. Acta 1973 64 147. Brunette M. G. Vigneault N. and Danan G. Anal. Biochem. 1978 86 229. Ryan D. E. and Holzbecher J. Int. J . Environ. Anal. Chem. 1971 1 159. Axelrod H. D. Bonelli J. E. and Lodge J. P. Anal. Chim. Acta 1970 51 21. American Association of Textile Chemists and Colorists Colour Index Second Edition Volume 3, Axelrod H. D. Bonelli J. E. and Lodge J. P. Anal. Chem. 1970 42 512; correction Anal. Chem., Oshima G.and Nagasawa K. Chem. Pharm. Bull. 1972 20 1492. Holzbecher J. and Ryan D. E. Anal. Chim. Acta 1974 68 454. Axelrod H. D. and Bonelli J. E. Environ. Sci. Technol. 1971 5 420. Musha S. Ito M. Yamamoto Y. and Inamori Y. J . Chem. SOC. Jpn. Pure Chem. Sect. 1959 80, Radley J. A. Analyst 1944 69 47. Ellis G. H. Zook E. G. and Baudisch O. Anal. Chem. 1949 21 1345. Bruce T. and Ashley R. W. Report 1973 AECL-4446 National Technical Information Service, Szebelledy L. and Gaal F. J. 2. Anal. Chem. 1934 98 255. Holme A. Acta Chem. Scand. 1967 21 1679. Szebelledy L. and Tanay S. 2. Anal. Chem. 1936 26 107. Korenman I. M. Zh. Anal. Khim. 1947 2 158. Murata A. and Yamauchi F. J . Chem. SOC. Jpn. Pure Chem. Sect. 1958 79 231. Tauboeck K. Naturwissenschaften 1942 30 439.White C. E. and Neustadt M. H. Ind. Eng. Chem. Anal. Ed. 1943 15 599. White C. E. Weissler A. and Busker D. Anal. Chem. 1947 19 802. White C. E. J . Chem. Educ. 1951 28 369. Sommer L. Chem. Listy 1957 51 2032. Parker C. A. and Barnes W. J. Analyst 1957 82 606. Parker C. A. and Barnes W. J. Analyst 1960 85 828. White C. E. and Hoffman D. E. Anal. Chem. 1957 29 1105. Sommer L. Collect. Czech. Chem. Commun. 1959 24 99. Elliott G. and Radley J. A. Analyst 1961 86 62. Shcherbov D. P. and Kagarlitskaya N. V. Tr. Kaz. Naucho-Issled. Inst. Miner. Syr’ya 1961 5 , Podchainova V. N. Skornyakova L. V. Tr. Ural. Politekh. Inst. 1967 No. 163 60. Marcantonatos M. Gamba G. and Monnier D. Helv. Chim. Acta 1969 52 538. Skorko-Trybula Z. and Boguszewska Z. Mikrochim.Acta 1976 2 335. Neelakantam K. and Rao L. R. Proc. Indian Acad. Sci. 1942 16a 349. Raju N. A. and Neelakantam K. Curr. Sci. 1958 27 482. Rao G. G. and Appalarju N. 2. Anal. Chem. 1959 167 325. Monnier D. Marcantonatos A. and Marcantonatos M. Helv. Chim. Acta 1964 47 1980. Kristalev P. V. and Shevchenko Ya. F. Sb. Nauch. Tr. Perm. Politekh. Inst. 1970 No. 71 38; Marcantonatos M. Marcantonatos A. and Monnier D. Helv. Chim Acta 1965 48 194. Marcantonatos M. and Monnier D. Helv. Chim. Acta. 1967 50 2068. Marcantonatos M. Monnier D. and Daniel J Anal. Chim. Acta 1966 35 309. Monnier D. and Marcantonatos M. Anal. Chim. Acta 1966 36 360. Monnier D. Liebich B. and Marcantonatos M. Fresenius 2. Anal. Chem. 1969 247 188. Monnier D. Liebich B. and Marcantonatos M. Anal.Chim. Acta 1970 52 305. 792. Chorley and Pickersgill England 1957 p. 3390. 1970 42 743. 1285. Washington DC 14pp. 255; Ref. Zh. Khim. 1962 15D53. Ref. Zh. Khim. 1971 13G227 May 1982 DETERMINATION OF INORGANIC ANIONS. A REVIEW 493 64. 65. 66. 67. 68. 69. 70. 71. 72. 73. 74. 75. 76. 77. 78. 79. 80. 81. 82. 83. 84. 85. 86. 87. 88. 89. 90. 91. 92. 93. 94. 95. 96. 97. 98. 99. 100. 101. 102. 103. 104. 105. 106. 107. 108. 109. 110. 111. 112. 113. 114. 115. 116. 117. 118. 119. 120. 121. 122. 123. 124. Monnier D. Menzinger C. A. and Marcantonatos M. Anal. Chim. Acta 1972 60 233. Monnier D. and Marcantonatos Mitt. Geb. Lebensmittelunters. Hyg. 1972 63 212.Afghan B. K. Gulden P. D. and Ryan J. F. Water Res. 1972 6 1475. Shcherbov D. P. and Korzheva R. N. Tezisy Dokladov Soveshchaniyapo Lyuminestsenta 1958 p. 65. Shcherbov D. P. and Korzheva R. N. T r . Kaz. Nauchno-Issled. Inst. Miner. Syr’ya 1960 No. 2, Shcherbov D. P. “Tezisy Dokladov Yubileinoi Sessii Posvyashchennoi 40-Letiyu Velikoi 0ktyabr’-Nazarenko V. A. and Vinkovetskaya S. J . Anal. Chern. USSR 1971 26 No. 2 700. Marcantonatos M. Monnier D. and Marcantonatos A. Helv. Chim. Acta 1964 47 705. Rigin V. I. and Melnichenko N. N. Zavod. Lab. 1967 33 3. Shibazaki T. Yakugaku Zasshi 1968 88 1393. Podchainova V. N. Anikeenko L. V. Vedernikov G. S. and Bogomolov S. G. Ural. Konf. Spek-trosk. 7th 1971 No. 2 110; Ref. Zh. Khim. 1972 13B162. Podchainova V. N. Skornyakova L.V. and Dvinyaninov B. L. Izv. Vyssh. Ucheb Zaved. Khim. Tekhnol. 1968 11 241. Lapid J. Farhi S. and Koresh Y. Anal. Lett. 1976 9 355. Pszonicki L. and Tkacz W. Chem. Anal. (Warsaw) 1970 15 809. Pszonicki L. and Tkacz W. Chem. Anal. (Warsaw) 1970 15 1097. Dabrowski J. and Pszonicki L. Chem. Anal. (Warsaw) 1971 16 51. Tkacz W. and Pszonicki L. Anal. Chim. Acta 1977 90 339. Tkacz W. and Pszonicki L. Chem. Anal. (Warsaw) 1971 16 535. Tkacz W. and Pszonicki L. Anal. Chim. Acta 1976 87 177. Hiirhammer L. and Hansel R. Arch. Pharm. (Weinheim) 1955 288 315. Hansel R. and Strasser F. Arch. Pharm. (Weinheinz) 1952 285 286. Hems R. V. Kirkbright G. F. and West T. S. Anal. Chem. 1970 42 784. Tan L. H. and West T. S. Anal. Chem. 1971 43 136. Tan L. H. and West T.S. Analyst 1971 96 281. Elliott G. and Radley J. A. Anal. Chem. 1961 33 1623. West T. S. “Chemical Spectrophotometry in Trace Characterisation-Chemical and Physical,” NBS Thorburn Burns D. and Hanprasopwattana P. Anal. Chim. Acta 1980 118 185. Podberezskaya N. K. Shilenko E. A. and Sushkova V. A. Issled. Obl. Khim. Fiz. Metod. Anal. Pilipenko A. T. Shevchenko T. L. and Volkova A. I. Zh. Anal. Khim. 1977 32 731. Haddad P. R. Talanta 1977 24 1. Babko A. K. and Chalaya 2. I. Ukr. Khim. Zh. 1964 30 268. Babko A. K. Chalaya 2. I. and Voronova E. D. Zavod. Lab. 1965 31 157. Babko A. K. and Vasilevskaya A. E. Ukr. Khim. Zh. 1967 33 314. Vasilevskaya A. E. “The Use of Organic Reagents in Analytical Chemistry,” Proceedings of the Vasilevskaya A. E. Nauch. Tr. Vses.Inst. Miner. Resur. 1971 5 22; Ref. Zh. Khim. 1972 9G114. Kirkbright G. F. Narayanaswamy R. and West T. S. Anal. Chem. 1971 43 1434. Kirkbright G. F. Narayanaswamy R. and West T. S. Analyst 1972 97 174. Ripau R. and Suteu A. Rev. Chim. Buc. 1967 12 1339. Bishop E. Anal. Chim. Acta 1950 4 6. Spence R. W. Straetz R. P. Krause D. P. Byerly W. M. Safranski L. W. West L. E. Waters, Willard H. H. and Horton C. A. Anal. Chem. 1952 24 862. Bouman J. Chem. Weekbl. 1955 51 33. Willard H. H. and Winter 0. B. Ind. Eng. Chem. Anal. Ed. 1933 5 7. Rodden C. J. Editor “Analytical Chemistry of the Manhattan Project,” Wiley New York 1950, Land D. B. and Edmonds S. M. Mikrochim. Acta 1966 1013. Guyon J. C. and Shults W. D. J . Am. Water Works Assoc. 1969 61 403. Gentry C. H.R. and Sherrington L. G. Analyst 1946 71 432. Powell W. A. and Saylor J. H. Anal. Chem. 1953 25 960. Schenk G. H. and Dilloway K. P. Anal. Lett. 1969 2 379. Bourstyn M. Bull. SOC. Chim. Fr. 1941 8 540. Taves D. R. Talanta 1968 15 1015. Fletcher M. H. and Milkey R. G. Anal. Chem. 1956 28 1402. Fletcher M. H. and Milkey R. G. J. Am. Chem. Soc. 1957 79 5425. Guyon J . C. and Lorah E. J. Anal. Chem. 1966 38 155. Vlasov N. A. Morgen E. A. and Tyutin V. A. Izv. Naucho-Issled. Inst. Nefte- ffglekhim. Sin. Vlasov N. A. Morgen E. A. and Tyutin V. A. Gidrokhim. Muter. 1969 50 92. Nasu T. Hokkaido Kyoiku Daigaku Kiyo Dai-2-Bu A 1972 23 35. Nasu T. Kitagawa T. and Mori T. Bunseki Kagaku 1970 19 673. Chaikin S. W. and Glassbrook T. D. Paper presented at Division of Analytical Chemistry Sym-posium on Air Pollution 124th Meeting American Chemical Society Los Angeles Calif.1953. Chaikin S. W. and Glassbrook T. D. Res. Ind. 1953 5 2. Ivie J . O. J Air Pollut. Control Assoc. 1965 15 195. 217. skoi Sotsialisticheskoi Revolyutsii,” Akad. Nauk Kaz. SSR Alma-Ata 1957. Monograph No. 100 National Bureau of Standards Washington D.C. 1967 pp. 215-301. Miner. Syr’ya 1971 90. Second All-Union Conference Saratov 1966 p. 204. J. I. and Wallace D. E. US Atomic Energy Commission 1951 ECD 3089. pp. 729-31. Irkutsk. Univ. 1969 11 (Pt. l) 136; Ref. Zh. Khim. 1969 23G162 GOMEZ-HENS AND VALCARCEL Thompson C. R. Zielenski L. F, and Ivie J. O. Atmos. Environ. 1967 1 253. Hayashi T. Ohgaki S. Yagi C. Kawai S. and Ohno T. Chem. Pharm. Bull. 1973 21 2141.Griinert A. Ballschmiter K. and Tolg G. Talanta 1968 15 451. Axelrod H. D. Cury J. H. Bonelli J . E. and Lodge J. P. Anal. Chem. 1969 41 1856. Hardwick B. A. Thistlethwayte D. K. B. and Fowler R. J. Atmos. Environ. 1970 4 379. Hardwick B. A. Thistlethwayte D. K. B. and Fowler R. J. Atmos. Environ. 1971 5 281. Hardwick B. A. Thistlethwayte D. K. B. and Fowler R. J. Atmos. Environ. 1971 5 282. Scaringelli F. P. Atmos. Environ. 1971 5 282. Zutshi P. K. Atmos. Environ. 1971 5 281. Colovos G. Haro M. and Freiser H. Talanta 1970 17 273. Yanysheva V. S. Zavod. Lab. 1964 30 23. Wronski M. Z. Anal. Chem. 1961 180 185. Babko A. K. Markova L. V. and Tsybina T. S. Zavod. Lab. 1964 30 648. Shafran I. G. Vzorova I. F. Dorosinskaya M. I. Fidlon L. K. and Yur’eva V.A. Metody Anal. Samoilov Ya. V. Byul. Izobr. Tovarnykh Znakov 1964 24 51. Wronski M. Chem. Anal. (Warsaw) 1971 16 439. Wronski M. Chem. Anal. (Warsaw) 1970 15 215. Mori I. Fujita Y . Goto M Furuya S. and Enoki T. Bunseki Kagaku 1980 29 145. Guyon J. C. Jones B. E. and Britton D. A. Mikrochim. Acta 1968 1180. Britton D. A. Guyon J. C. Anal. Chim. Acta 1969 44 397. Alford W. C. Shapiro L. and White C. E. Anal. Chem. 1951 23 1149. Britton D. A. and Guyon J. C. Microchem. J . 1969 14 1. Volmar V. Bull. SOC. Chim. Fr. 1933 53 385. Hanker J. S. Gelberg A. and Witten B. Anal. Chem. 1958 30 93. McKinney G. L. Lau H. K. Y. and Lott P. F. Microchem. J . 1972 17 375. Lau H. K. Y. and Lott P. F. Talanta 1970 17 717. Iritani N. Miyahara T. and Takahashi I. Bunseki Kagaku 1968 17 1075. Vernon F. and Whitham P. Anal. Chim. Acta 1972 59 155. Bark L. S. and Rixon A. Analyst 1970 95 786. Nazarenko V. A. and Shustova M. B. Zavod. Lab. 1958 24 1344. Yanysheva V. S. and Sazonova Z. A. Metody Anal. Khim. Reakt. Prep. Gos. Kom. Sov. Min. SSSR Kasiura K. Chem. Anal. (Warsaw) 1969 14 1325. Schulz D. B. Passoneau J . V. and Lowry 0. H. Anal. Biochem. 1967 19 300. Guilbault G. G. Kramer D. N. and Hackley E. Anal. Biochem. 1967 18 241. Guilbault G. G. Brignac P. and Zimmer M. Anal. Chem. 1968 40 190. Khim. Reakt. Pre$. Gos. Kom. Sou. Min. S S R Khim. 1965 No. 11 81. Khim. 1962 No. 4 133. Received August 4th 1981 Accepted November 18th 1981 494 125. 126. 127. 128. 129. 130. 131. 132. 133. 134. 135. 136. 137. 138. 139. 140. 141. 142. 143. 144. 145. 146. 147. 148. 149. 150. 151. 152. 153. 154. 155. 156. 157. 158. 159

ISSN:0003-2654    

DOI:10.1039/AN9820700465

出版商:RSC    

年代:1982

数据来源: RSC

摘要:

Analyst, May, 1982, VoL. 107, PP. 495-499 Spectrophotometric Determination of Rhenium in 495 Alkaline Solution* L. V. Borisova, A. N. Ermakov and A. B. lsmagulova Vernadsky Institute of Geochemistry and Analytical Chemistry, USSR A cademy of Sciences, Vorobjevskoe Shosse 47a, Moscow 117334, USSR The reaction of perrhenate with hydroxylammonium chloride (NH,OHCl) has been studied. Hydroxylammonium chloride reacts with rhenium in 8-10 M sodium hydroxide solution to produce a yellow complex which has Amax, a t 300 nm with a molar absorptivity of 7.9 x lo3 1 mol-l cm-*. The stoicheiometry of the complex has been studied spectrophotometrically using different procedures. A method for the spectrophotometric determination of rhenium has been developed, and this has been applied to the determination of rhenium in molybdenum - rhenium and tungsten - rhenium alloys.Keywords : Rhenium determination ; spectrophotometry ; hydroxylammonium chloride ; alloys Photometric methods allow the determination of microgram amounts of rhenium in numerous analytical materials such as ores, slags, industrial semi-products, waters and a1loys.l In order to decompose rhenium-containing products, alkaline fusion is used to eliminate heavy metal impurities in the form of hydroxides. The known photometric methods for the determination of rhenium have been developed mostly for acidic media. So far only two quantitative methods for the determination of rhenium in weakly alkaline medium are known, based on the absorbance of the ionic associate of perrhenate with tetraphenylarsonium and by the absorbance of the perrhenate ion itself in ammonia s ~ l u t i o n .~ * ~ The disadvantages of these methods are low sensitivity ( E w 3600) and poor selectivity, which are due to the fact that the determination is carried out in the ultraviolet region at 230nm where many ions are able to absorb. We have studied the reaction of perrhenate with the widely used hydroxylammonium chloride4 in highly alkaline medium. Taking into consideration the redox potentials in strongly alkaline media for the system Re(VI1) - Re(1V) and presumably for Re(V) and Re(V1) in the presence of hydr~xylamine,~ one can expect the redox reaction of the perrhenate ion with hydroxylamine (HAM) to take place. Experimental Solutions All chemicals and reagents were of analytical-reagent grade and all solutions were prepared using distilled water.Rhenium( V I I ) standard solution, 0.1-0.01 M. Prepared from potassium perrhenate [potassium rhenate(VI1) , KReO,] and perrhenic acid [tetraoxorhenic(VII) acid, HReO,] and standardised by the spectrophotometric thiourea meth0d.l Hydroxylammonium chloride solutions, 0.1 and 1 M. The hydroxylamine concentrations were determined by iodimetric titration.6 Sodium hydroxide solution, 12 M. Metal solutions f o r interference tests. Prepared by weighing the required amounts of the Working solutions were prepared by dilution. different salts and adding water until complete dissolution was obtained. Apparatus was used. A Specord ultraviolet - visible spectrophotometer with matched 1- and 0.1-cm silica cells * Presented a t the 5th SAC International Conference on Analytical Chemistry, Lancaster, July 20-25th, 1980.496 BORISOVA et aZ.: SPECTROPHOTOMETRIC DETERMINATION Analyst, VoZ. 107 Procedures The reaction of the perrhenate ion with hydroxylamine in alkaline medium was investi- gated. The effect of the absorbance of a series of solutions containing sodium hydroxide - ReO, - hydroxylamine on reagent concentration and time was studied. The influence of the concentration of sodium hydroxide was studied in the concentration range 1-12 M. The absorbance of the complex was also studied as a function of the con- centration of hydroxylamine. The solutions were always prepared with the same order of addition : metal, sodium hydroxide solution, reagent.The composition of the complex formed in solution was determined spectrophotometrically using different procedures : Job’s continuous variation method,‘ the limiting logarithmic methods and Asmus’s m e t h ~ d . ~ 1.4 1.0 Q) C (0 e 2 0.6 2 0.2 Determination of Rhenium with Hydroxylamine To an aliquot of solution containing 0.023-1.8 mg of rhenium, add 20 ml of 12 M sodium hydroxide solution and 2 ml of 0.1 M aqueous hydroxylamine solution. Mix the solutions and heat for 20 min on a boiling water-bath until the volume of solution in the flask reaches 25ml. Measure the absorbance at 300nm against a blank prepared in the same manner but omitting rhenium. The content of rhenium in the solution is calculated from a cali- bration graph. A calibration graph prepared using the same procedure (2 ml of 0.1 M hydroxylamine solution, 20 ml of 12 M sodium hydroxide solution) was rectilinear, passing through the origin, in the range 0.023-1.8 mg of rhenium. The effect of various ions was studied on a sample containing 0.2 mg of rhenium. - - - - Results and Discussion When solutions of rhenium and hydroxylamine were mixed, a soluble yellow complex was obtained.Fig. 1 illustrates the absorption spectra of solutions of perrhenate ions, sodium hydroxide, hydroxylamine and the product of their reaction. The spectrum of the reaction product has an intense band at 300 nm. Fig. 2 shows the dependence of the absorbance of the solution on the concentration of sodium hydroxide with hydroxylamine in excess. The reaction begins at a sodium hydroxide concentration of 3 M and reaches a maximum at 10 M.The measurements of the spectra of these series of solutions showed that the spectra are completely identical, which is indicative of the presence of the same compound over the range of sodium hydroxide concentrations under investigation. \ Y 100 240 280 320 Wavelengthhm Fig. 1. Absorption spectra of A, potassium perrhenate, [Re] = 0.173 x M ; B, hydroxylamine, 0.34 x M ; C, sodium hydroxide solution, 10 M ; and D, the product of their reaction. I = 1 cm. 1.4 0, m g 1.0 +! a 2 0.6 0 0.2 0 4 8 12 Sodium hydroxide concentration/M Fig. 2 Dependence of absorbance of the solutions of the coloured compound on the concentration of sodium hydroxide. [Re] = 0.19 x M ; hydroxylamine concentration = 0.34 x M.May, 1982 OF RHENIUM IN ALKALINE SOLUTION 497 Experiments on the effect of time and temperature show that the yellow colour of the complex was completely developed within 50min at room temperature (Fig. 3) and within 20 min at 60-80 "C.The absorbance remained stable for at least 4 h. Fig. 4 shows the spectra of solutions with increasing concentrations of hydroxylamine and constant concentrations of rhenium and sodium hydroxide. The spectra changed on decreasing the Re: HAM ratio from 1 : 1 to 1 : 40. The intense absorbance at 230 nm, which corresponds to the absorbance of the perrhenate ion, decreased with increasing concentration of hydroxylamine in the system. 13 a 0 1 2 3 4 5 Timelh 1.4 1 .o a C m e a 2 0.6 0.2 2 I I f 260 300 Wavelengthhm Fig. 3. Influence of contact time on absorbance of the solution.[Re] = 1 x 1 0 - 3 M ; hydroxylamine Fig. 4. Changes in absorbance spectra of concentration, 2 x 10-2 M ; sodium hydroxide con- potassium perrhenate solutions with increasing centration, 10 M ; wavelength, 300 nm; I = 1 cm. concentrations of hydroxylamine relative to constant concentrations of sodium hydroxide (10M) and rhenium (0.173 x W 3 M ) . = 1 cm. [Re] : [hydroxylamine] ratio: A, 1 : 1 ; B, 1:5; C, 1 : l O ; D, 1:20; and E, 1:40. Simultaneously there appeared a band at 300nm, the intensity of which increased with increasing hydroxylamine concentration. The absorbance reached a maximum with an Re: HAM ratio of 1 : 20. Further increases in the excess of hydroxylamine relative to rhenium revealed no changes in either the solution spectra or the intensity of the bands at 300 nm.The dependence of the absorbance changes on hydroxylamine concentration at 300 nm is shown in Fig. 5. In order to determine the composition of the yellow complex, the continuous variation, limiting logarithmic and Asmus methods were used.- The results of the first method are illustrated in Fig. 6, for an isomolar series of solutions with a total concentration of the components of 1.6 x The Re: HAM molar ratio of 1 : 2 corresponds to the optimum value of the reacting components in solution. The formation instability constant of the rhenium compound is considered to be (0.53 5 0.02) x in accordance with the isomolar series and the data from the molar ratio method. The complex was retained by cation-exchange resins, and therefore this system is cationic in alkaline solution.The data obtained allowed us to devise a photometric method for the determination of rhenium in the system rhenium - hydroxylamine - sodium hydroxide.1° The conditions considered to be optimum for the formation of the coloured compound in this system are: a molar ratio of rhenium to hydroxylamine of 1 : 20 in a 10 M solution of sodium hydroxide; the colour reaches its final intensity after 20 min at 60-70 "C. Under the optimum con- ditions used for the formation of the rhenium complex, Beer's law is obeyed between 0.07 x and 2.5 x loA4 M of rhenium and the molar absorptivity at 300 nm is 7900 -J= 200 1 mol-l cm-l. The apparent molar absorptivity is 7900 & 200 1 mol-l cm-1 at 300 nm.M at 300 nm.498 1.6 1.2 al 0 C m 2 0.8 I) a 0.4 % BORISOVA et aZ. : SPECTROPHOTOMETRIC DETERMINATION Analyst, VoZ. I07 0 Concentration of ligand x 1 0 - 3 / ~ Fig. 5 . Dependence of absorbance of the solutions on hydroxylamine con- centration. [Re], 0.173 x 1 0 - 3 ~ ; sodium hydroxide concentration, 10 M ; wavelength, 300 nm; I = 1 cm. 1.6 1.2 s $ 0.8 I) 4 0.4 0 0.2 0.4 0.6 0.8 1.0 Molar fraction of Re(VII1 I 1 I I 1 I 1.0 0.8 0.6 0.4 0.2 0 Molar fraction of hydroxylamine Fig. 6. Determination of stoicheio- metry of the reaction of perrhenate with hydroxylamine in 10 M sodium hydroxide solution. Wavelength, 300 nm; 1 = 1 cm. The sensitivity of the method according to Sandell is 0.023 pg cm-2. The optimum concentration range is 0.28 x 10-4-1.65 x lo4 M of rhenium. For five samples containing 0.093 and 0.200 mg per 25 ml the mean standard deviations were 0.003 1 and 0.0052 mg per 25 ml, respectively.An interference study was carried out under the optimum conditions described above, the absorbance being measured at 300nm with hydroxylamine in excess and with a rhenium concentration of 0.4 x 1 0 - 4 ~ . It was found that the following excess amounts relative to rhenium do not interfere with the determination : cadmium, 10-fold; copper, 100-fold; zinc, 10-fold; lead, 12-fold; thallium, 5-fold; arsenic, 50-fold; molybdenum and tungsten, 45-fold; S042-, 200-fold; vo43-, 10-fold; and BiO,3-, %fold. However, oxidising agents such as hydrogen peroxide and nitric acid do interfere in the determination. Determination of Rhenium in Alloys The proposed method was applied satisfactorily to the determination of rhenium in alloys.Rhenium - molybdenum and rhenium - tungsten alloys were dissolved by anodic oxidation in alkaline hydroxides originally applied to ruthenium alloys and later to rhenium alloys.ll A weighed bead of the alloy (1.5 g) on the anode is covered with alkali - peroxydisulphate (persulphate) electrolyte [lOml of 4 M sodium hydroxide solution and 3 4 ml of 0.1 M potassium peroxydisulphate (K,S,O,!] and 0.15-0.20 g of alloy is dissolved at a current density of 0.5-2 A cm-2 in 15-20 mn. The amount dissolved is found by subsequently weighing the bead. The rhenium solution is diluted to 25 ml with 4 M sodium hydroxide solution. Aliquots of the prepared solutions, containing 0.13-0.75 mg of rhenium, were used for determination of rhenium by the spectrophotometric method as described above.The results are given in Table I and were compared with those obtained by an electrochemical method.12 TABLE I DETERMINATION OF RHENIUM IN STANDARD ALLOYS WITH MOLYBDENUM AND TUNGSTEN (n = 5) Rhenium found/mg I Amount dissolved/ Stated Re Present Electrochemical Sample type mg contentlmg method method12 Mo-Re-20 . . .. 140.0 28.0 27.0 & 0.7 26 & 0.7 Mo-Re-47 . . .. 51.5 24.2 23.6 & 0.7 24.5 & 0.7 W-Re-25 . . .. 107.0 26.75 25.6 f 0.8 25.9 f- 0.8May, 1982 OF RHENIUM IN ALKALINE SOLUTION 499 References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. Borisova, L. V., and Ermakov, A. N., “Analiticheskaya Khimiya Reniya (Analytical Chemistry of Rhenium),” Nauka, Moscow, 1974. Andrew, T. R., and Gentry, C. H. R., Analyst, 1957, 82, 372. Borisova, L. V., Gerlit, Yu. B., and Ermakov, A. N., Thesis, Doklady Technicheskogo Soveshchaniya, “Perspektivy Razvitiya i Metody Izvlecheniya Redkikh i Rasseyannykh Elementov iz Rud i Mestorozhdenii Armenii i Soyuza,” Izd. Akad. Nauk Azm. SSR, Erevan, 1962. Brikun, I. K., Kozlovskii, M. T., and Nikitina, L. V., “Gidrazin i Gidroksilamin i Ikh Primenenie v Analiticheskoi Khimii,” Izd. Nauka Kaz. SSR, Alma-Ata, 1967. Latimer, W. M., “The Oxidation States of the Elements and Their Potentials in Aqueous Solutions,” Prentice-Hall, New York, 1952, p. 97. Bartusek, M., Fresenius 2. Anal. Chem., 1960, 173, 193. Job, P., Ann. Chim. (Paris), 1928, 9, 113. Bent, H. E., and French, C. L., J . A m . Chem. Soc., 1941, 63, 568. Asmus, E., Fresenius 2. Anal. Chem., 1960, 178, 104. Borisova, L. V., Ermakov, A. N., and Ismagulova, A. B., Byull. Izobr., No. 19, 1980, Avtorskoe Cotton, T. M., and Woolf, A. A., Anal. Chew., 1962, 34, 1385; 1964, 36, 248. Ismagulova, A. B., Zavod. Lab., 1980, 46, 1088. Svidetelstvo 735 975. Received April 16th, 1981 Accepted October Sth, 1981

ISSN:0003-2654    

DOI:10.1039/AN9820700495

出版商:RSC    

年代:1982

数据来源: RSC

摘要:

500 Analyst, May, 1982, Vol. 107, p p . 500-504 Determination of Rhenium Based on the Formation of Rhenium(V1) Oxide Halide Complexes by Spectrophotometry and Electron Spin Resonance Spectroscopy* L. V. Borisova, A. N. Ermakov, Ye. I. Plastinina, 0. D. Prasolova and I. N. Marov Vernadsky Institute of Geochemistry and Analytical Chemistry, USSR Academy of Sciences, Vorobjevskoe Shosse 47a, Moscow 117334, USSR The possibility of obtaining solutions of rhenium(V1) compounds and their analytical applications has been studied. The rhenium(V1) compounds formed, ReOC1,- and ReOBr,, are characterised by specific absorbance spectra and electron spin resonance (ESR) spectra. New quantitative methods of rhenium determination were devised. The formation of ReOBr, in sulphuric acid from the ReO,- ion and KBr was used for the development of a selective spectrophotometric method for the determination of rhenium and the ability of ReOBr, to be extracted into organic solvents was used for rhenium deter- mination by ESR.On the basis of ReOC1,- formation, a quantitative method for the deter- mination of rhenium by the spectrophotometric titration of ReO,- in a mixture of sulphuric and hydrochloric acids using an iron(I1) solution was devised. The methods were also applied to alloys. Keywords 1 Rhenium determination ; rhenium( V I ) oxide halide complexes ; spectrophotometry ; ESR spectroscopy ; alloys Rhenium(V1) compounds have not been used in analytical chemistry because of the absence of practicable methods for obtaining them in solution. The small amount of published data indicates the difficulty of obtaining rhenium(V1) compounds and the necessity for using inert atmospheres, non-aqueous solvents and a dry-box for their stabi1isation.lv2 We have con- ducted a systematic study of the conditions for the stabilisation of rhenium(V1) compounds in solution. The ReO, - H,SO, - HC1 [Fe(II)] and ReO, - €€,SO, - KBr systems were studied in greatest detail.The rhenium(V1) compounds formed, ReOC1,- and ReOBr,, have reasonable stability in solution in air and specific absorbance spectra with intense bands in the visible region of the spectrum and have the electron spin resonance (ESR) spectrum characteristic of rhenium(V1) (Table I) .3 The specificity of the electronic spectra of rhenium(V1) oxide halide complexes and their ESR spectra made it possible to develop quantitative methods for the determination of rhenium.TABLE I PARAMETERS OF ELECTRONIC AND ESR SPECTRA OF RHENIUM(VI) OXIDE HALIDE COMPLEXES g, AII/crn-l A,/crn-' Xmax./nm (Emax.) gll Compound ReOC1,- in H,SO, . . . . 275 (6000), 420 (6000), 520 (400) 2.011 1.96 0.939 0.915 ReOBr, in H,SO, . . . . 560 (2200), 650 (2050) 2.173 1.770 1.014 0.826 ReOBr, in toluene . . . . 560 (2 560), 650 (4270) - - - - Experimental Concentrated sulphuric and hydrochloric acids, iron(I1) sulphate, potassium bromide, All reagents were of analytical- potassium perrhenate and extra-pure toluene were used. reagent grade and all solutions were prepared using distilled water. * Presented at the 5th SAC International Conference on Analytical Chemistry, Lancaster, July 20-25th, 1980.BORISOVA, ERMAKOV, PLASTININA, PRASOLOVA AND MAROV 501 Electronic spectra were recorded on a Specord ultraviolet - visible spectrophotometer in the range 300-750nm in 1- and 2-cm silica cells.ESR spectra were taken on a Varian V-4502 spectrometer at -140 "C in capillaries of 3 mm diameter. The magnetic field was calibrated using the ESR spectrum of manganese(I1) in magnesium oxide. The g factor was determined using the Strong Pitch standard (Varian) with g = 2.0028. The resonance field was determined using an IMI-2 magnetic-intensity meter and a GZ-4 frequency indi- cator. Results and Discussion A study of the Re(VI1) - H,SO, - HC1 system has shown that the rhenium(V1) oxide chloride complex of composition ReOC1,- is formed on the reduction of rhenium(VI1) with hydrochloric acid.4 A prolonged time is necessary, however, for quantitative reduction, but if iron(I1) sulphate is used as the reducing agent rhenium(VI1) is reduced to rhenium(V1) almost instantaneously.4 Fig.1 shows the absorption spectra of a series of solutions with various Re(VI1) : Fe(I1) ratios, from which it follows that the rhenium(V1) oxide chloride com- plex is characterised by an intense absorption band at 430 nm, reaching a maximum with an Re(VI1) : Fe(I1) ratio of 1 : 1. With further addition of iron(I1) the absorbance at 430 nm decreases almost to zero, which is associated with the formation of the rhenium(V) complex ReOCl,", which does not absorb in this region of the spectrum. The conditions for the formation of the rhenium(V1) oxide chloride complex did not make it possible to devise direct spectrophotometric and ESR spectroscopic methods, but were.satisfactory for the development of a spectrophotometric titration method. The high molar absorptivity for the ReOC1,- ion in comparison with the chloride complexes of rhenium(V) and -(IV), and the high stability (1-2 h), made it possible to develop a method for the quantitative determination of rhenium by spectrophotometric titration at 430 nm. A mixture of concentrated sulphuric and hydrochloric acids in a molar ratio from 14: 1 to 90 : 1, which corresponds to the optimum conditions for rhenium(V1) complex formation,, was used as the medium. Fig. 2 shows the titration graph for perrhenate [rhenate(VII), Re0,-] ion solution with iron(I1) sulphate solution, with a clearly defined maximum.Calcu- lations have shown this maximum point corresponds to an Re(VI1) : Fe(I1) molar ratio of 1: 1 and the quantitative formation of rhenium(V1). The rhenium content (CRe) can be determined by means of the equation C,, = V ' F e C F e / V R e , where VFe is the volume of standard iron( 11) solution used, CFe is the concentration of standard iron( 11) solution and VR, is the volume of rhenium solution used. The limit of detection of rhenium by this method is 6 pg d-l. 1.5 1 D 400 500 600 Wavelengthlnrn Fig. 1 . Variation of absorption spectra of solutions in the titration of HReO, with iron(I1). [Re], 2.95 x lo-, M ; and [H,SO,] : [HCl] = 80 : 1 mlm. [Fe(II)] to [Re(VII)]: A, 0; B, 0 .3 : l ; C, 0 . 7 : l ; D, 1: 1 ; E, 1.4: 1 ; F, 2 . 8 : l . Comparison solution, water. I = 1 cm. 0.75 a, 0.5 0 (0 9, 0, 2 0.25 0 1 2 Volurne/ml Fig. 2. Titration of 1.47 x M HReO, solution with iron(I1) solution in a mixture of concentrated acids in the molar ratio [H,S04] : [HCl] = 80: 1.502 Analyst, VoZ. I07 The intensity of the colour of the solution in the titration reaches a maximum almost instantaneously and remains constant for 1-2 h. The determination is not hindered by a 100-fold excess of copper(1) or cobalt(II), a 50-fold excess of nickel(II), a 20-fold excess of molybdenum(V) or any amount of iron(I1). BORISOVA et al. : DETERMINATION OF RHENIUM BY Working Procedure To 5 m l of 1 7 - 1 8 ~ sulphuric acid containing not less than 30pg of rhenium(VI1) add 0.1 ml of concentrated hydrochloric acid and titrate with 1 x 10-3-1 x M iron(I1) sulphate solution in 5 M sulphuric acid.Measure the absorbance a t 430 nm immediately after the addition of each portion of titrant. Find the end-point as the intersection of the two portions of the titration graph. In determining 30 pg of rhenium the standard deviation was 1.3 pg (three determinations). Investigation of the Re(VI1) - H,SO, - Br- system has shown that it is preferable to the Re(VI1) - H,SO, - Cl- system because rhenium(VI1) is rapidly and quantitatively converted into stable rhenium(V1) oxide bromide after addition of excess of bromide. This was used to develop direct spectrophotometric and ESR spectroscopic methods for determining rhenium. A study of the Re(VI1) - H,SO, - KBr system has shown that with excess of bromide, blue rhenium(V1) oxide bromide (ReOBr,) is formed.Fig. 3 shows the electronic spectra of rhenium(V1) oxide bromide solutions in sulphuric acid at different concentrations of Br- ions. The spectra are characterised by two intense absorption bands at 560 and 650nm, reaching a maximum value a t an Re: Br- ratio from 1 : 20 to 1 : 50. Rhenium(V1) oxide bromide is formed in solutions of not less than 16 M sulphuric acid. In the presence of a 20-50-fold excess of Br- ions relative to rhenium the formation of rhenium(V1) oxide bromide terminates after 20-30 min. Beer’s law is valid in the rhenium concentration range 0.2 x lo-, -6 x lo-, M. The regression line for these measure- ments on pure solutions was found to be A = (2090 * 120)C, where A is absorbance and C (from 0.2 x lo-, to 6.0 x The correlation coefficient The solutions are stable for 2 4 h.M) is the concentration of rhenium. &as 0.999. The sensitivity was 4.8 pg ml-l (0.2 X M). D 1 .o a, c m 2 $ 0.5 n 6 0 20 16 1 Wavenumber, Y x 10-3/cm-’ Fig. 3. Variation of absorption spectra of ReOBr, solutions with Br- concentration. [Re], 2 x l o - 4 ~ . [Br-1: A, 4 x B, 1 x C, 2 x D, 4 x E, 1 x F, 2 x and G, 4 x M. I = 2 cm (A-D) and I = 1 cm (E-G). Determination of Rhenium by Spectrophotometry from solution. An increasing rhenium concentration causes the precipitation of rhenium(V1) oxide bromide The precipitates are readily soluble in dry organic solvents such as toluene,May, 1982 SPECTROPHOTOMETRY AND ESR SPECTROSCOPY 503 chloroform, diethyl ether and acetic acid.The spectra of the extracts are similar to the above spectra of rhenium(V1) oxide bromide, and H,SO,.ReOBr, passes entirely into the extract. Beer's law is valid for the rhenium(V1) oxide bromide extract in toluene over the more extensive rhenium concentration range of 2.5 x 10-,-50 x lo-, M. To plot the calibration graph, to an aliquot of 0.001 M potassium rhenate(VI1) (KReO,) solution in concentrated sulphuric acid (0.1-3 ml) is added up to 5 ml of concentrated sulphuric acid and 0.01 g of potassium bromide with stirring. After 20-30 min the absorb- ance of the solution is measured relative to concentrated sulphuric acid at 650 nm. We studied the effect of the following ions on the determination of rhenium: Zn, Cd, Co(II), Cu(II), Ni(II), Fe(II), Mn(II), Nb and Zr taken as sulphates, Ru(III), Rh(III), Pd(II), Pt(IV), Pb and Bi taken as chlorides and When rhenium is determined spectrophotometrically at a concentration of 3 x lo-, M, platinum metals form poorly soluble precipitates and chromium compounds yield a coloured solution that does not interfere in the determination of rhenium at 650 nm.The concentrations of all the elements examined were 10-3-10-4 M. WO,2-, V03- and CrO,2-. Determination of Rhenium by ESR Spectroscopy The linear regression equation between the signal intensity, I , and the concentration, C, from 1 x M of rhenium was found to be I = (0.45 When determining rhenium by the ESR method, aliquots of a 0.01 M solution of potassium rhenate(VI1) in concentrated sulphuric acid (0.1-3 ml) are diluted to 5 ml with concentrated sulphuric acid, 0.05g of potassium bromide is added, after 20min extraction is performed with 5 ml of toluene and the ESR spectrum is recorded. The use of extraction eliminated a negative effect due to freezing of the concentrated sulphuric acid solution.For the deter- mination of rhenium the first line of parallel orientation located in the region of low field, H = 139936.8Am-l (Fig. 4), is used. The dependence of the intensity of this line on rhenium(V1) concentration is a straight line. to 6 x 0.25) + (940 & 28)C. /I Strong Pitch standard signal \ 9950 A m-' H J I I I 1 I B 6 5 4 3 2 1 I I I ' A 1 2 3 4 5 6 + H Fig. 4. ESR spectrum of ReOBr, solution in toluene: [Re], 2 x 10-3 M ; [Br-1, 1 x 10-1 M ; range 398000 A m-l; Hc, 242780 A m-l; and temperature, - 150 "C.A, Perpendicular orientation and B, parallel orientation. Strong Pitch, g = 2.0028.504 BORISOVA, ERMAKOV, PLASTININA, PRASOLOVA AND MAROV The determination of rhenium by the ESR method can be hindered by paramagnetic ions. The elements investigated under the conditions for the formation and extraction of rhenium(V1) oxide bromide do not yield paramagnetic ions capable of being extracted into the organic phase. The methods are applicable to the determination of rhenium in alloys. Determination of Rhenium in Alloys Take weighed samples of rhenium - molybdenum, rhenium - tungsten and rhenium - tungsten - niobium - zirconium alloys of 0.074, 0.157 and 0.425 g, respectively, and de- compose them with 30% hydrogen peroxide with slight heating.Destroy the excess of hydrogen peroxide by boiling. Filter off the precipitates and wash them with hot water, then evaporate the solution to 1 ml. Cool the solutions obtained, dilute them to 25 ml with concentrated sulphuric acid and determine rhenium using one of the methods proposed above. When rhenium is determined by the spectrophotometric method, aliquots (0.3 ml for rhenium - molybdenum, 0.15 ml for rhenium - tungsten and 0.1 ml for rhenium - tungsten - zirconium - niobium) of solutions obtained are diluted to 5 ml with concentrated sulphuric acid, 0.01 g of potassium bromide is added and after 20 min the absorbances are measured at 650 nm. When rhenium is determined by the ESR method, aliquots (0.2 m1) of the solutions obtained are diluted with concentrated sulphuric acid to 2 ml (for rhenium - molybdenum and rhenium - tungsten alloys) or to 5 ml (for the rhenium - tungsten - zirconium - niobium alloy), 0.05 g of potassium bromide is added and after 20 min, the solutions are extracted with 2 ml or 5 ml of toluene, respectively.The ESR spectra are recorded and the rhenium concentration is calculated from a calibration graph. The amounts of rhenium found (n = 3, P = 0.95) were as follows: by spectrophotometry, in rhenium - molybdenum alloy 48.58 & 2.27y0, in rhenium - tungsten alloy 24.48 1.26% and in rhenium - tungsten - zirconium - niobium alloy 23.49 5 0.57%; by ESR spectro- scopy, in rhenium - molybdenum alloy 50.22 & 2.45y0, in rhenium - tungsten alloy 25.65 & 2.64% and in rhenium - tungsten - zirconium - niobium alloy 22.48 & 1.43%. Calculate the rhenium concentration from a calibration graph. 1. 2. 3. 4. References Borisova, L. V., and Yermakov, A. N., “Analiticheskaya Khimiya Reniya (Analytical Chemistry of Edwards, H., and Brisdon, A., J. Inorg. Chem., 1968, 7 , 1898. Marov, I. N., Borisova, L. V., Plastinina, Ye. I., and Zhukov, V. V., Zh. Neorg. Khim., 1976, 21, Borisova, L. V., Yermakov, A. N., and Prasolova, 0. D., Dokl. Akad. Nauk SSSR, 1974, 218, 581. Rhenium),” Nauka, Moscow, 1974. 1641. Received April 16th, 1981 Accepted October 8th, 1981

ISSN:0003-2654    

DOI:10.1039/AN9820700500

出版商:RSC    

年代:1982

数据来源: RSC

摘要:

Analyst, May, 1982, Vol. 107, $9. 505-510 Com bined Ion Exchange - Spectrophotometric Method for the Simultaneous Determination of Vanadium and Cobalt in Biological Materials T. Kiriyama Laboratory for Chemistry, Faculty of Education, Kagoshima University, Kagoshima, Japan 505 and R. Kuroda Laboratory for Analytical Chemistry, Faculty of Engineering, University of Chiba, Yayoi-cho, Chiba, Japan A combined anion exchange - spectrophotometric method has been developed for the determination of vanadium and cobalt in biological materials. A sample is dry ashed at 420 "C, the ash (ca. 0.5 g) is decomposed with a mixture of perchloric, nitric and hydrofluoric acids, and finally is taken up in hydro- chloric acid. The metals are adsorbed by anion exchange on an Amberlite CG 400 (SCN-) column from a dilute ammonium thiocyanate - hydrochloric acid solution. The adsorbed vanadium and cobalt are separated chromato- graphically by elution with 12 M hydrochloric acid and 2 M perchloric acid, respectively.Both fractions of vanadium and cobalt are subsequently purified by anion exchange from 0.1 M hydrochloric acid - 3 yo V / V hydrogen peroxide for vanadium and 6 M hydrochloric acid for cobalt. Vanadium and cobalt in the effluents are determined spectrophotometrically with 4-( 2-pyrid- y1azo)resorcinol. Results for the determination of vanadium and cobalt in various materials of biological origin and in NBS standard biological samples are given. Keywords : Simultaneous determination of vanadium and cobalt ; biological materials ; spectrophotornetry 4-(2-Pyridylazo)resorcinol (PAR) is a highly sensitive photometric reagent for determining vanadium192 and ~ o b a l t , ~ but it reacts with many metals, so lacks selectivity.The chelates of PAR with cobalt and vanadium react with quaternary ammonium salts to form red association complexes extractable in chloroform in the presence of a large excess of ethylene- diaminetetraacetic acid (EDTA) [for cobalt, nickel and iron(II)] and trans-l,2-cyclohexane- diaminetetraacetic acid (CyDTA) [for vanadium(V)] .4 This method is highly sensitive for nickel, cobalt, iron(I1) and vanadium(V), but they obviously interfere with each other. Therefore, the effective application of PAR as a highly sensitive spectrophotometric reagent for determining vanadium and cobalt necessitates the preliminary separation or concentra- tion of vanadium and/or cobalt prior to their spectrophotometric determination with PAR.Solvent extraction and ion exchange along with the extensive use of masking agents have been general practice for the determination of vanadium with PAR in plant material,5 copper ores,6 silicate rocks79* and sea waterg and for the determination of cobalt in iron and steels,IO with added zephiramine, and in sea water.ll This investigation concerns the development of a highly. sensitive spectrophotometric method using PAR for the simultaneous determination of vanadium and cobalt in a variety of biological materials, coupled with the anion-exchange chromatographic separation in thiocyanate media.12 Chromatographic adsorption and elution of vanadium and cobalt in the thiocyanate media with subsequent anion-exchange purification of vanadium in a hydrogen peroxide medium and of cobalt in hydrochloric acid solution provide a basis for the selective isolation of both elements prior to their spectrophotometric determination.The combined ion exchange - spectrophotometric method allows analyses of several biological materials including the NBS standard reference materials, orchard leaves and bovine liver, to be conducted effectively. Experimental Reagents Dissolve vanadyl( IV) chloride and ammonium vana- date(V) in distilled water to yield 5.05 mgml-l of vanadium(1V) and 2.50 mgml-1 of Vanadium(1V) and -( V ) solutions.506 KIRIYAMA AND KURODA: ION EXCHANGE - SPECTROPHOTOMETRIC Analyst, Vol.107 vanadium(V) , respectively. Standardise these solutions by titration with 0.01 M EDTA solution using copper - PAN as the indicator13 (copper - PAN is a mixture of copper - EDTA and 1- (2-pyridylazo)naphth-2-01). Dissolve cobalt(I1) chloride hexahydrate in 0.1 M hydrochloric acid to give a 5.55 mg ml-l cobalt solution. Standardise by titration with 0.01 M EDTA solution using copper - PAN as the indicator.l3,l4 Dissolve 0.25 g of 4-(2-pyridylazo)resorcinol in 8.5 ml of 1% m/V sodium hydroxide solution and dilute to 250 ml with distilled water, for use in the vanadium deter- mination. Mix 6 ml of saturated bromine water and 100 ml of 1 M sodium hydroxide solution. Prepare by mixing 25 parts of 0.5 M disodium hydrogen phosphate solution and 24 parts of 0.5 M sodium dihydrogen phosphate solution. Prepare by mixing 25 parts of 0.5 M sodium citrate solution and 0.3 part of 0.5 M citric acid solution.Cobalt solution. PAR solution. Dilute further five-fold with water, for use in the cobalt determination. Bromine - sodium hydroxide solution. Phosphate bufer solution, pH 6.5. Citrate bufer solution, pH 6.8. Apparatus Ion-exchange column A The glass column was approximately 3.8 cm in length and 1.5 cm i.d., supported with a plug of glass-wool in the bottom of the column. The column consisted of a slurry of 3.0g of Amberlite CG 400 in the thiocyanate form (100-200 mesh). Ion-exchange column B sisted of a slurry of 2.0 g of Amberlite CG 400 in the chloride form (100-200 mesh). 50 mm. A column of approximately 6 cm in length and 1.0 cm i d .was used. The column con- A Hitachi, Type 101, spectrophotometer was used with glass cells of optical path length Procedure ash. Dry oxidise a known mass of wet sample at 420 "C for 48 h, which yields about 0.5 g of Ion-exchange separation Place the ash in a PTFE beaker and moisten with water. Add 2ml of concentrated perchloric acid and 4 rnl of concentrated nitric acid. Heat the beaker until the appearance of white fumes. Add 2 ml of concentrated perchloric acid and again evaporate to dryness to expel the fluoride. Take up the residue in 10 ml of 1 M hydrochloric acid. Add 85 ml of water and 5 ml of 2 M ammonium thiocyanate solution. Wash the column with 50 ml of 0.1 M hydrochloric acid - 0.1 M ammonium thiocyanate solution. Strip the vanadium by elution with 40 ml of 12 M hydrochloric acid. Elute the cobalt with 50 ml of 2 M perchloric acid.To the effluent containing vanadium add 2 ml of concentrated nitric acid and heat carefully to destroy the thiocyanate. Treat further with 1 ml of concentrated nitric acid and again evaporate to dryness. Moisten the residue with 0.5 ml of 6 M hydrochloric acid, add 10 ml of water and heat gently to dissolve the residue, then cool. Add 3 ml of 30% V/V hydrogen peroxide and 17 ml of water to the solution and allow it to pass through column B, previously conditioned with 0.1 M hydro- chloric acid - 3% V/V hydrogen peroxide solution. Wash the column with 25 ml of the same hydrochloric acid - hydrogen peroxide solution and then remove the vanadium by elution with 20 ml of 2 M hydrochloric acid.Evaporate the effluent nearly to dryness and deter- mine the vanadium spectrophotometrically with PAR, as described later. Add 2 ml of concentrated nitric acid to the effluent containing cobalt and heat gently to decompose the thiocyanate. Take up the residue in 10ml of 6 M hydrochloric acid. Pass the resulting solution down column B, previously conditioned with 6 M hydrochloric acid. Wash the column with 25 ml of 6 M hydrochloric acid. Combine both effluents and evaporate the mixture nearly to dryness. Add 2 ml of concentrated hydrofluoric acid and evaporate to dryness. Pass the thiocyanate solution down column A. Evaporate until fumes of sulphuric acid appear. Evaporate the solution nearly to dryness.M a y , 1982 METHOD FOR V A AND CO I N BIOLOGICAL MATERIALS 507 Treat further with 1 ml of concentrated nitric acid to destroy any organic matter that is present.Evaporate to dryness and proceed as described under Spectrophotometric deter- mination of cobalt. Spectrofihotometric determination of vanadium nearly to dryness and cool. solution and allow the mixture to stand for 30 min. solution and 2.5ml of a pH 6.5 phosphate buffer solution. 6.5 & 0.1 with 1 M hydrochloric acid. the PAR solution, dilute to 25 ml and allow to stand for 5 min. 545 nm against the reagent blank. Take up the residue from the effluent with 2 ml of ammonia solution (1 + l), evaporate Add 5 ml of water and 2 ml of the bromine - sodium hydroxide Add 0.5 ml of 1.2% m/V phenol If necessary, adjust the pH to Add 2 ml of 0.01 M CyDTA solution and 1.0 ml of Measure the absorbance at Spectro+hotometric determination of cobalt Dissolve the residue from the effluent containing cobalt with a small volume of water.Add 2.5 ml of a pH 6.8 citrate buffer solution and adjust the pH to 6.8 -J= 0.2 with 2% m/V sodium hydroxide solution. Add 1.0 ml each of PAR solution, 0.05 M EDTA solution and 0.2 M potassium cyanide solution. After 20 min measure the absorbance at 510 nm against a reagent blank. Mix well and dilute to 25 ml with water. Results and Discussion The adsorption behaviour of metal ions on a strongly basic anion-exchange resin in thio- cyanate media has been investigated extensi~ely.l~~~5 Metals that form thiocyanato com- plexes adsorb strongly on the resin, particularly vanadium(1V) and -(V) and cobalt exhibit pronounced adsorption, sufficient to allow a concentration stage, even from large-volume sea-water sample^.^^^^ The distribution coefficients, Kd, of vanadium( IV) and -(V) and cobalt on Amberlite CG 400 (SCN-) are about lo4 and 2.4 x lo3, respectively, in a 0.1 M ammonium thiocyanate solution 0.1 M hydrochloric acid medium.Adsorbed vanadium can be removed easily by elution with concentrated hydrochloric acid, but cobalt remains on the resin under these conditions, being stripped by 2 M perchloric acid. A chromatogram is illustrated in Fig. 1, in which approximately 100 pg each of vanadium( IV) [or vanadium(V)] and cobalt are separated successfully in the thiocyanate medium. Table I summarises the results of the separation of vanadium(1V) or vanadium(V) and cobalt in binary mixtures in the thiocyanate medium. Quantitative separations can be accomplished using this system.S+W-+k-12 M HCI-2.0 M HCIO4 $? 6o 2 8 9 40 - oc 20 - n L- ” 0 20 40 60 80 100 u ’, Eluentiml I Fig. 1. Chromatographic separation of vanadium and cobalt. S, Sample solution, 0.1 M NH,SCN - 0.1 M HC1; W, wash solution, 0.1 M NH,SCN - 0.1 M HC1. Approximately 100 pg each of V(1V) or V(V) and Co(I1) loaded and chromatographed. Broken line, separation of V(V) and Co; and solid line, separation of V(1V) and Co.508 KIRIYAMA AND KURODA: ION EXCHANGE - SPECTROPHOTOMETRIC Analyst, VoZ. 107' TABLE I ANION-EXCHANGE SEPARATION OF VANADIUM(IV) OR -(V) AND COBALT I N THIOCYANATE MEDIUM Run V(1V) 1 101 2 101 3 4 5 101 6 101 7 8 4.04 9 Added/pg - 7 V(V) co V(IV) 111 96.9 111 100 100 111 100 111 4.44 96.3 4.44 93.8 4.44 95.3 Average: 96.5 100 4.44 4.00 4.44 Found, % 1 v (V) co 102 101 100 102 103 101 105 100 97.2 101 96.4 103 97.1 101 101 The system allows the selective separation of vanadium(1V) and -(V).When applied, however, to the separation of vanadium in some types of marine organisms, such as the cuttle- fish Sepiotezdhis Zessoniana, the effluent contained varying amounts of aluminium, calcium and phosphate, which give a slight white precipitate when adjusting the pH to 6.5 & 0.1 in the subsequent spectrophotometric determination with PAR. The contamination can be removed by thorough washing of the column, prior to the elution with concentrated hydro- chloric acid, but to ensure a high quality of the separation we decided to add a simple anion- exchange separation stage.The system consisted of 0.1 M hydrochloric acid containing 3% V/V hydrogen peroxide - Amberlite CG 400 (Cl-). The system permits a moderate adsorp- tion of vanadium(1V) and vanadium(V), but most metals that form chloro-complexes, including aluminium and calcium, do not exhibit any adsorption. The distribution co- efficients of vanadium(1V) and vanadium(V) are given in Table I1 as a function of hydrogen peroxide concentration in 0.1 M and 1 M hydrochloric acid media. The value of the coefficient passes through a broad maximum at a 0.9% V/V hydrogen peroxide concentration for both vanadium(1V) and vanadium(V). Taking the decomposition of peroxide into account, a 0.1 M hydrochloric acid - 3% V/V hydrogen peroxide medium was used for the separation.The vanadium that is adsorbed can easily be stripped by elution with 2 M hydrochloric acid. This additional separation leads to a successful spectrophotometric determination of vanadium with PAR. Use of CyDTA in the spectrophotometric procedure also improves the selectivity significantly for the determination of vanadium ; magnesium, aluminium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, silver, tin, tungsten, mercury and lead are well masked to make further provision against any unfore- seen interferences. Cobalt can be removed from the column by elution with 2 M perchloric acid together with many other adsorbed elements. However, the use of EDTA and cyanide as the masking agents makes the spectrophotometric determination selective for cobalt, except for nickel and iron.Nickel does not adsorb on to the column from the acid - thiocyanate medium, but the iron does, along with the cobalt. In this method iron was simply removed by a filtration through an Amberlite CG 400 (Cl-) column (column B) from 6 M hydrochloric acid. TABLE I1 DISTRIBUTION COEFFICIENTS OF VANADIUM ON AMBERLITE CG 400 (Ck) I N HYDROCHLORIC ACID - HYDROGEN PEROXIDE MEDIA Hydrogen peroxide concentration, % VlV Hydrochloric acid I \ Element concentration/M 9.0 3.0 0.90 0.090 V(1V) . . .. 1 4 5 3 3 .. .. 1 3 3 3 2 .. 0.1 57 69 71 48 V(V) V(1V) . . V(V) .. .. 0.1 53 68 79 58May, 1982 509 Table I11 lists results for the separation and determination of vanadium(1V) and cobalt in the presence of iron as well as in synthetic mixtures simulating a biological ash.In spite of the presence of appreciable amounts of interfering ions including magnesium, calcium, aluminium, iron, copper, nickel and zinc, vanadium(1V) and cobalt can be determined with average recoveries of 96.3 and 98.2y0, respectively, at a 4-pg level. Similar results were also obtained for the separation of vanadium(V) and cobalt. Several materials of biological origin were analysed for vanadium and cobalt with and without the addition of known METHOD FOR VA AND CO I N BIOLOGICAL MATERIALS TABLE I11 ANION-EXCHANGE SEPARATION OF VANADIUM(IV) AND COBALT I N SYNTHETIC MIXTURES Amount added/ pg Amount found/pg r A .. . . 101 4.44 105, 101 4.24, 4.56 A ... . 4.04 4.44 3.96, 3.89 4.44, 4.22 B .. . . 4.04 4.44 3.85, 3.89 4.41, 4.66 c .. . . 4.04 4.44 3.81, 3.85 4.44, 4.31 D .. . . 4.04 4.44 3.85, 4.04 4.13, 4.14 A 7 f A \ Foreign ions* V(1V) Co V(IV) co Average?: 3.89 f 0.07 4.36 & 0.18 * A, 1.00 x lo4 pg of Fe(II1); B, A + 3.13 x lo4 pg of A1 + 2.92 X lo4 pg of H3P04 + 71.3 pg of Cu(I1) + 85.6 pg of Ni; C, B + 3.97 x lo4 pg of Na + 4.40 x lo4 pg of K + 3.80 x lo4 pg of Mg + 4.26 x lo4 pg of Ca; and D, C + 7.20 x lo3 p g of Zn. t Average for V(1V) calculated with exception of line 1 values. amounts of vanadium and cobalt. The results are summarised in Table IV. The precision (as relative standard deviations) range from 3 to 7% for vanadium and from 3 to 11% for cobalt except for Trichiurus Zepturus (cutlass fish) and pig liver.For the cutlass fish extremely low concentrations of both elements are responsible for the poor precision. The low precision for both elements in the pig liver is perhaps reflected partly by the inhomo- geneity of the samples taken. TABLE IV DETERMINATION OF VANADIUM AND COBALT IN BIOLOGICAL MATERIALS Amount added, p.p.m. Content in original sample, p.p.m.+ -a- ? A I , Sample V co V Green tea (7.3-8.9 g taken) . . . . . . . . 0 0 0.515, 0.548, 0.559 0.507 0.141 0.543 0.900 0.250 0.529 Monostroma nitidum (8.9-10.6 g taken) . . . . (0539 f 0.017)t 0 0 2.34, 2.42, 2.65 2.23 0.247 2.50 4.50 0.499 2.69 Trichiurus lepturus (40-45 g taken) . . . . . . 0 0.024 7 0.048 6 Crassostrea gigas (21-26 g taken) . . . . . . 0 0.190 0.357 Sepioteuthis lessoniana (38-54 g taken) .. . . 0 0.026 1 0.049 8 Pig liver (30-35 g taken) . . . . . . . . 0 0.0324 0.066 3 0 0.0138 0.0270 0 0.052 7 0.099 1 0 0.0146 0.0276 0 0.018 2 0.036 8 (2.52 f 0.15)t 0.000 9 0.000 5 (0.0007 f 0.0004)t 0.275, 0.246, 0.248 0.250 0.250 (0.254 & 0.012)t 0.0175, 0.0186, 0.0190 0.015 7 0.0174 (0.0176 f 0.0013)t 0.0081, 0.0070, 0.0073 0.007 8 0.0054 (0.0071 f 0.0Oll)t 0.0000, 0.000 9, 0.001 1 co 0.287, 0.264, 0.229 0.243 0.260 (0.257 f 0.022)t 0.282, 0.285, 0.283 0.283 0.265 (0.280 & 0.008)t 0.0058, 0.0052, 0.0045 0.0000 0.0026 (0.0036 f 0.0024)t 0.0704, 0.0733, 0.0744 0.0773 0.078 2 (0.0747 f 0.0031)t 0.005 8. 0.005 1. 0.006 5 0.005 2’ 0.005 2 (0.0056 f 0.0006)t 0.0119, 0.0145, 0.0174 0.011 0 0.011 2 (0.0132 j, 0.0027)t Results are for the amount present in the samples after subtracting the known amount added.t Values in parentheses are the average values for each sample.510 KIRIYAMA AND KURODA The results for the determination of vanadium and cobalt in two NBS standard biological reference materials are shown in Table V. The values for cobalt, particularly those for bovine liver, are in reasonably good agreement with the data previously reported. Scant informa- tion is available for vanadium in the two biological standards. Values for orchard leaves are within the range reported by Gladney.l* The values for bovine liver are rather close to a lower extreme given by Gladney, and therefore more data on vanadium contents are highly desired. TABLE V DETERMINATION OF VANADIUM AND COBALT IN TWO NBS STANDARD REFERENCE MATERIALS Content found, p.p.m.Element Orchard leaves Bovine liver Reference Vanadium .. .. Cobalt.. .. .. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 0.460, 0.512, 0.467 0.600 f. 0.150 (Average 0.480 f 0.028) 0.610 0.282, 0.283, 0.327 0.19 0.170 f 0.090 0.200 0.170 (Average 0.297 f 0.026) 0.00, 0.01, 0.02 0.033-0.600 0.231, 0.226, 0.218 (Average 0.225 i 0.007) 0.240 i 0.060 0.180 0.254, 0.260 0.233 f 0.005 0.254 This work Gladney16 Nadkami and Morrison1' This work Fudagawa and Kawase18 Gladney16 NBS Certificate of Analysis (1977) Nadkami and Morrisod7 Dermelj et aZ.1@ Abukawa et aLzo References Shijo, Y., and Takeuchi, T., Bunseki Kagaku, 1965, 14, 115. Kawahata, M., Mochizuki, H., Kajiyama, R., and Ichihashi, K., Bunseki Kagaku, 1965, 14, 348. Shijo, Y . , and Takeuchi, T., Bunseki Kagaku, 1964, 13, 536. Yotsuyanagi, T., Yamashita, R., and Aomura, K., Bunseki Kagaku, 1970, 19, 981. Minczewski, J., Chwastowska, J., and Pham Thi Hong Mai, Analyst, 1975, 100, 708. Kozlicka, M., and Wojtowicz, M., Chem. Anal. (Warsaw), 1971, 16, 739. Strelow, F. W. E., Liebenberg, C. J., and Victor, A. H., Anal. Chem., 1974, 46, 1409. Akaiwa, H., Kawamoto, H., and Kondo, H., Bunseki Kagaku, 1974, 23, 402. Kiriyama, T., and Kuroda, R., Anal. Chim. Acta, 1972, 62, 464. Okochi, H., Bunseki Kagaku, 1972, 21, 51. Kiriyama, T., and Kuroda, R., Fresenius 2. Anal. Chem., 1977, 288, 354. Kiriyama, T., and Kuroda, R., Anal. Chim. Acta, 1978, 101, 207. Flaschka, H., and Abdine, H., Chemist-Analyst, 1956, 45, 58. Flaschka, H., and Abdine, H., Mikrochim. Acta, 1956, 770. Kawabuchi, K., Hamaguchi, H., and Kuroda, R., J , Chromatogr., 1965, 17, 567. Gladney, E. S., Anal. Chim. Acta, 1980, 118, 385. Nadkami, R. A., and Morrison, G. H., J . Radioanal. Chem., 1978, 43, 347. Fudagawa, N., and Kawase, A., Bunseki Kagaku, 1980, 29, 6. Dermelj, M., Vakselj, A., Ravnik, V., and Smodis, B., Radiochem. Radioanal. Lett., 1979, 41, 149. Abukawa, J., Higuchi, H., Sato, K., Bando, S., and Hamaguchi, H., Bunseki Kagaku, 1979, 28, 506. Received August 6th, 1981 Accepted November 9th, 1981

ISSN:0003-2654    

DOI:10.1039/AN9820700505

出版商:RSC    

年代:1982

数据来源: RSC

摘要:

Analyst, May, 1982, Vol. 107, pp. 511-518 Liquid = Liquid Extraction Combined with Atomic- absorption Spectrometry for Determination of Copper in Waters, Foods and Analytical Reagents Using 1,ZNaphthoquinone Thiosemicarbazone 51 1 M. Silva and M. Valcarcel Department of Analytical Chemistry, Faculty of Sciences. University of Cordoba, Cordoba, Spain An atomic-absorption spectrometric method for the determination of trace amounts of copper in solution with 1,2-naphthoquinone thiosemicarbazone is described. This compound reacts with copper in a weakly acidic medium t o produce a complex that can be extracted into isobutyl methyl ketone. The atomic absorption of the organic phase is measured a t 324.8 nm. The sensitivity of the method is 0.6 ng ml-1 for 1% absorption in aqueous solution and the presence of several milligrams of 55 foreign ions is tolerated. The method has been applied successfully to the analysis of waters, foods and analytical reagents.Keywords : Copper determination ; atomic-absorption spectrometry ; 1,2- naphthoquinone thiosemicarbazone; waters, foods and analytical-reagent analysis In recent years several atomic-absorption spectrometric methods, based on the separation and pre-concentration of copper by liquid - liquid extraction, have been reported. Ammonium tetramethylenedithiocarbamate,l sodium 1 diethyldithiocarbamate (DEDT(J2 and 8- hydroxyquinoline (8-OHQ)3 are frequently used as chelating agents. Although isobutyl methyl ketone (IBMK) is generally used as a solvent in these systems, chl~roform,~ ethyl acetate5 and butyl acetate6 have also been employed.Many other complexing reagents have been used to separate and/or concentrate copper. Several authors have employed extraction processes based upon halide or thiocyanate complex ion-association system^.^-^ Other systems used include the extraction of copper with diphen ylt hiocarbazone in carbon tetrachloride, lo mercapt obenzo t hiazole in but yl acet at e,ll potassium ethylxanthate in fBMK,12 picolinealdehyde 2-quinolylhydrazone in 3-methyl- butanol or 4-methy1pentan-2-onel3 and 2-thenoyltrifluoroacetone in IBMK.14 Measurement of copper atomic absorbance has been used in a number of indirect deter- m i n a t i o n ~ , ~ ~ - ~ ~ such as the determination of nitrate by extraction of its ion pair with the copper(1) - 2,9-dimethyl-1 ,lo-phenanthroline complex at pH 3-6 in IBMK.20 This paper describes a sensitive method for the determination of trace amounts of copper by atomic-absorption spectrometry after extrackion using 1,2-naphthoquinone (NQT, shown below) and IBMK.The NQT complex is stable in IBMK medium. The method has been applied successfully to the determination of copper in waters, foods and analytical reagents. NQT The application of the reagent to the determination of other metals (zinc, cadmium, mercury, lead, etc.) by liquid - liquid extraction combined with atomic-absorption spectro- metry is currently being studied in our department. Experimental Apparatus A Perkin-Elmer 380 atomic-absorption spectrometer, equipped with a standard air - acetylene burner-head and a multi-element (titanium - aluminium - iron - copper) hollow-512 SILVA AND VALCARCEL : LIQUID - LIQUID EXTRACTION AND AAS Analyst, Val.I07 cathode lamp, was used. The instrumental settings used are summarised in Table I. Perkin-Elmer 402 and Pye - Unicam SP-500 spectrometers were also employed. The pH measurements were carried out with a Beckman 3500 pH meter equipped with a combined glass - calomel electrode. TABLE I ATOMIC-ABSORPTION CONDITIONS FOR COPPER DETERMINATION Wavelength . . .. . . .. Lamp current .. .. .. Slit-width . . . . .. .. Air pressure . . .. .. . . Air flow-rate . . .. .. . . Acetylene pressure . . . . .. Acetylene flow-rate . . .. .. Aspiration rate . . .. .. Integration time . . .. .. 324.8 nm 30 mA 0.7 nm 30 p.s.i.g. 19.5 1 min-l 8 p.s.i.g.2.0 1 min-' 2 s 5.0 ml min-l Reagents Standard copper solutions Prepare a 1.000 mg ml-l stock solution by dissolving 1.000 g of pure copper metal in the minimum volume of nitric acid (1 + 1 V/V) and diluting to exactly 1 1 with 1% V/V nitric acid. Solutions of lower concentrations are prepared by appropriate dilution. 1,2-N ap ht hoquinone t hiosemicar baxone reagent solution For the second solution dissolve 0.1 g of NQT in the minimum volume of NN-dimethylformamide (2 ml) and dilute to 100 ml with IBMK. The synthesis of NQT has been described previously.21 Prepare 0.1% m/V solutions in ethanol and IBMK. This solution is stable for several days. B u f e r solution (PH 4.65) 4.65 (measured using a pH meter). purification. Add glacial acetic acid to 0 .5 ~ sodium acetate trihydrate solution to adjust the pH to All other solutions are prepared from analytical-reagent grade chemicals without further Procedure Determination of copper with NQT Take less than 100ml of the sample solution, containing 0.2-16Opg of copper, in a separating funnel, add 2.5 ml of buffer solution and mix well. Add 10 ml of NQT solution in IBMK, shake vigorously for 30 s, then allow the phases to separate and transfer the organic layer into a glass-stoppered tube containing anhydrous sodium sulphate. Aspirate the organic phase into an oxidising air - acetylene flame and measure the atomic absorption a t 324.8 nm. Construct the calibration graphs by measuring up to 15pg of copper when the burner slot is in the normal position and up to 160 pg when the slot is at an angle of 60" to the optical path and proceed as described above for the extraction procedure. Other experimental procedures The pre-treatments required by various samples are described below.Water samfiZes. Mineralisation of foods. The water samples should be filtered before the determination in order to remove any suspended matter. In all instances, except for milk, the samples should be treated according to the IUPAC recommended procedure as follows. In a beaker, gently warm an accurate mass or volume of the food sample with 10-20 ml of sulphuric - nitric acid (1 + 1 V / V ) . In order to destroy the organic matter completely add several drops of hydrogen peroxide. Collect the remaining solution in a 100-ml calibrated flask and dilute to volume with distilled water.May, 1982 513 For mineralisation of milk samples, the classical procedure, consisting of treatment with 20% m/V trichloroacetic acid, is employed.Dissolution of analytical reagents. The analytical-reagent grade reagents iron( 111) nitrate and sodium sulphite are dissolved in distilled water. The aluminium ribbon is dissolved according to the following procedure. In a beaker, treat 1.1544 g of sample with the mini- mum volume of hydrochloric acid (1 + 1 V / V ) and several drops of mercury(I1) salt solution as a catalyst. Dilute the solution to 100 ml with 1% V/V hydrochloric acid. FOR CU IN WATERS, FOODS AND ANALYTICAL REAGENTS a, C m 0, 0.1 8 2 Results and Discussion - Photometric Characteristics of Copper - NQT Complex When dilute copper(I1) solutions in acid or alkaline medium (optimum acidity, pH 0.73-3.0 and 5.5-9.5) and a 0.1% m/V solution of NQT in ethanol are mixed, a red complex is formed immediately.The absorption spectrum of this chelate shows that the wavelength of maxi- mum absorbance is 565 nm. The stoicheiometry of the chelate has been determined by Job’s22 and Irwing and Pierce’s23 methods for which the experimental data were obtained in homogeneous and two-phase systems, respectively. In both instances, one complex species with a metal to ligand ratio of 1 : 2 has been found. The absorptiometric determination of copper in aqueous - ethanolic medium (1 + 4 V/V) gave a molar absorptivity of c = 1.69 x lo4 1 rnol-l cm-l and a Sandell’s sensitivity for copper of 0.0037 pg cmW2.In order to avoid the high proportion of ethanol and the great number of interferences in the homogeneous medium, the complex was extracted. This extractive method has been used satisfactorily for the determination of trace amounts of copper by flame atomic- absorption spectrometry with an increased sensitivity and selectivity. Liquid - Liquid Extraction of Copper Followed by Atomic-absorption Spectrometry Choice of extracting solvent and e$ect of p H Isobutyl methyl ketone proved to be the best of the aliphatic oxygenated solvents tried because the copper chelate showed a maximum atomic-absorption intensity in this solvent. Other solvents, such as chloroform, carbon tetrachloride and benzene were not employed, in order to avoid the formation of toxic products in the flame and the back-extraction process in the experimental procedure.At pH values higher than 11, an emulsion is produced. For control of the pH of the extraction, 2.5 ml of buffer solution (pH 4.65) were added when the phase-volume ratio was less than 5 , and 5.0 ml were added when higher ratios were present. Copper was quantitatively extracted in the pH range 3.5-7.1 as seen in Fig. 1. 0 2 4 6 8 10 12 PH Fig. 1. Effect of pH on extraction of 1 pg ml-l of copper with NQT. C N ~ T , 4.40 x M. Extraction eficiency and stability The recovery factors in the extraction of copper were calculated by means of a series of experiments in which the atomic absorption of copper in the organic phase was compared with a standard prepared in water-saturated IBMK.In all instances, several amounts of514 SILVA AND VALCARCEL: LIQUID - LIQUID EXTRACTION AND AAS Analyst, VOl. 107 copper (0.2-160 pg) were extracted completely from aqueous solutions with an extraction efficiency higher than 95% when 10 ml of 0.1% m/V NQT solution in IBMK were employed. A second extraction with another 10 ml of reagent solution showed that the copper content was negligible. The atomic absorption of the copper complex remained constant at room temperature for a t least 1 week. Efect of reagent concentration, shaking time and ionic strength M is adequate for the complete extraction of the amounts of copper used, but for the majority of extractions, a concentration of 4.4 x 10-3 M (0.1% m/V) was chosen. However, when the extraction of copper was carried out in the presence of high amounts of foreign ions (see below, Study of irtterferences) higher shaking times for the complete extraction of copper must be employed.The ionic strength of the aqueous phase does not affect the atomic absorption of the extracted complex. On the other hand, the same constant measurements were obtained when 1-5 ml of buffer solution (pH 4.65) were added. Any NQT concentration between 1.7-8.7 x The extraction is complete after shaking for 30s. Efect of phase-volume ratio The volume of the aqueous phase was varied in the range 10-300 ml and the volume of the organic phase was kept constant at 10 ml (0.1% m/V NQT), giving a phase-volume ratio ranging from 1 to 30. As seen in Fig. 2, the absorbance increases exponentially with an increasing phase-volume ratio (or volume of aqueous phase).This increase in absorbance is merely due to the dissolution of IBMK in the aqueous phase. If the extraction is carried out with phase-volume ratios higher than 10 (error greater than 3%), the absorbance must be corrected for the decrease in the volume of organic phase. This correction, as observed in Fig. 2, is not necessary when smaller ratios are employed. 0.2 I 1 I A I 0 5 10 15 20 25 30 Phase-volume ratio (aqueousiorganic) Fig. 2. Effect of phase-volume ratio on extrac- tion of 0.25 p.p.m. of copper with 10 ml of 0.1% m/V NQT solution: A, without correction of absorbance; and B, with correction of the organic phase volume after shaking. Atomic-absorption Determination of Copper Calibration graphs Under the optimum conditions used two linear calibration graphs are obtained for the determination of copper.The first one, for the range 0-1.5 pg ml-l of copper (related to organic phase), when the burner slot is parallel to the optical path (normal position) and the second one, for the range 0-16 pg ml-l of copper, when the slot is at 60" to the optical path.May, 1982 515 The sensitivity is about 4.5 times greater for IBMK solutions than for aqueous solutions (0.020 pg ml-l for 1% absorption for organic solutions and 0.090 pg ml-l for aqueous solutions). The relative sensitivity according to the phase-volume ratio is 0.6 ng ml-l when the volume of the aqueous phase is 300 ml (extraction with 10 ml of organic phase). The mean values of results from 11 samples each containing 0.25 p.p.m.(0" rotation scale of the burner) or 5.00 p.p.m. of copper (60" of rotation scale of the burner) gave the coefficients of variation of the method as h0.96 and &0.82y0, respectively. FOR C U IN WATERS, FOODS AND ANALYTICAL REAGENTS Study of interferences Copper (2.5 pg per 10 ml of organic solution) was determined in the presence of various amounts of 55 foreign ions. The tolerance limits (Table 11) show that copper can be deter- mined in the presence of a 5000-fold excess of a great number of diverse ions including most of those that are commonly associated with copper in natural and synthetic mixtures. TABLE I1 TOLERANCE LIMITS OF EXTRACTION - ATOMIC-ABSORPTION DETERMINATION OF COPPER WITH NQT Results are for 2.5 p g of copper per 10 ml of solution. Tolerance limit/ .pg per 10 ml 12 500 Ions tolerated Cd(II), Zn(II), Fe(III), Co(II), Sn(IV), Mo(VI), Se(IV), V(V), Mn(II), Cr(III), La(III), U022+, W(VI), As(III), As(V), Ca(II), Ba(II), Sr(II), Mg(II), Be(II), Tl(I), Li(I), K(I), NH,+, SiO,2-, Po,3-, S20g2-, SCN-, F-, C1-, Br-, I-, ClO,-, Cr042-, Br0,-, IO,-, 104-, B40,2-, tartrate, citrate, C0,2-, CH,COO-, NO,- 2 500 1250 Sb(III), Ag(I), Ni(I1) Bi(III), Hg(II), Pb(II), Ti(IV), In(II1) 250 Zr(IV), Th(IV), S20,2-, C20,2- Tolerance limits for lead(II), bismuth(III), antimony(II1) and nickel(I1) increased sub- stantially in the presence of tartrate, those for zirconium(IV), thorium( IV) and titanium( IV) increase in the presence of fluoride and mercury(I1) and indium(II1) were tolerated to a higher extent if iodide and thiocyanate, respectively, were present.In all instances, the masking agent concentration was 5000 pg ml-l and the tolerance limits were increased up to a ratio of copper to foreign ion of 1 : 5000. If any of the Group 1-111 metals (hydrogen sulphide scheme) that react with the reagent are present in ratios of 1 : 5000, a higher shaking time (3 min) and concentration of reagent (0.2% m/V) must be employed in order to effect the total extraction of copper. Applications To test the reliability of the proposed method, it was applied to the determination of copper in waters, foods and analytical reagents. In all instances, the standard addition method was employed. Several known and incr'easing amounts of copper (0, 1, 2 and 3 pg) were added to four aliquots of sample solution. The extraction procedure was carried out as indicated under Experimental and the atomic-absorption values of these extracts were plotted against the added copper concentration.The straight line was extrapolated back to the concentration axis and the negative intercept gave the concentration of the sample solution. In order to detect the existence of possible interferences, the copper recovery was calculated by comparing the results obtained before and after the addition of the copper standard solutions. The results obtained for the analysis of different aliquots of the prepared solutions are shown in Tables I11 and IV. These data demonstrate the reliability of the proposed methods for the determination of copper in these samples.Conclusions It has been shown that copper concentrations in the nanogram per millilitre range can be determined by atomic-absorption spectrometry after liquid - liquid extraction with the516 SILVA AND VALCARCEL : LIQUID - LIQUID EXTRACTION AND AAS Analyst, VoZ. I07 TABLE I11 DETERMINATION OF COPPER IN WATERS AND FOODS USING THE NQT METHOD Sample Swamp water . . Residual water . . Industrial water Milk . . .. Red wine .. Orange juice . . Rice . . .. Chocolate .. Cheese . . .. Amount taken . . .. 100 ml .. .. 100 ml . . .. 100 ml .. .. 50 ml .. .. 100 ml . . .. 50 ml . . . . 5.0165g .. .. 1.9683g .. . . 1.0538g Copper found* 5.4 p.p.b.t 208.3 p.p.b. 179.6 p.p.b. 86.9 p.p.b. 110.3 p.p.b. 919.9 p.p.b. 5.17 pg 8-l 12.05 pg g-l 20.12 pg g-1 Recovery, % 99.3 f 0.7 99.9 f 0.8 99.8 & 1.0 100.1 f 1.8 98.9 f 1.2 100.9 f 1.1 98.7 f 2.0 100.0 f 1.4 99.6 f 1.2 * Average of 8 separate determinations.t Parts per los. TABLE IV DETERMINATION OF COPPER IN ANALYTICAL REAGENTS Reported maximum Sample value, yo Found, yo Aluminium ribbon (Merck, GR) . . . . 0.005 0.00249 0.00006 Iron(II1) nitrate* (Merck, GR) . . .. 0.005 0.00050 f 0.00002 Sodium sulphite (Merck, GR) . . .. 0.001 0.000049 f 0.000003 * Sodium fluoride was added as a masking agent. NQT - IBMK system. The method has been compared, advantageously, with other methods reported previously (see Table V). In this table several characteristics for the determination of copper using an air - acetylene flame are shown. The following conclusions can be drawn from the data in Table V: (a) it is possible to extract the complex over a wide range of acidity and the complex is very stable in IBMK solution; (b) in most instances the proposed method offers a greater sensitivity for the deter- mination of copper; (c) the coefficient of variation obtained using the NQT method is, generally, smaller than that found in other determinations; (d) by using the NQT method, higher ratios of foreign ions can be tolerated than is the case when other reagents mentioned in the literature are used; and (e) by extraction into IBMK, the formation of toxic products in the flame is avoided. Finally, some recent paper^^^,^^ have described methods similar to that reported here, involving the use of liquid - liquid extraction combined with graphite furnace atomisation for the determination of copper in several samples (waters and foods).1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. References Allan, J . E., Spectrochim. A d a , 1961, 17, 459. Dean, J . A., and Cain, C., Anal. Chem., 1957, 29, 530. Goto, H., and Sudo, E., Bunseki Kagaku, 1961, 10, 175. Baker, A. S., and Smith, R. L., J . Agric. Food Chem., 1974, 22, 103. Magee, R. J., and Rahman, A. K. M., Talanta, 1965, 12, 409. Mehlich, A., and Bowling, S. S . , Commun. Soil Sci. Plant Anal., 1975, 6, 113. Tsutsumi, C., Koizumi, H., and Yoshikawa, S., Bunseki Kagaku, 1976, 25, 150. Kono, T., and Nemori, A., Bunseki Kagaku, 1975, 24, 419. Spivakov, B. Y., Lebadev, V. I., Shkinev, V. M., Krivenkova, N. P., Plotnikova, T. S., Kharlamov, Jamro, G.H., and Frei, R. W., Mikrochim. Acta, 1970, 429. Robinson, J. L., Barnekow, R. G., and Lott, P. F., A t . Absorpt. Newsl., 1969, 8, 60. Aihara, M., and Kiboku, M., Bunseki Kagaku, 1975, 24, 447. Frei, R. W., Bidleman, T., Jamro, G. H., and Novratil, O., I n t . J . Environ. Anal. Chem., 1971, 1, 75. Devoto, G., BoZZ. SOC. Ital. Biol. Sper., 1968, 44, 1249. Houser, M. E., and Fauth, M. I., Microchem. J . , 1970, 15, 339. Le Bihan, A., and Courtot-Coupez, J., Bull. SOC. Chim. Fr., 1970, 406. Le Bihan, A., and Courtot-Coupez, J., Analusis, 1974, 2, 695. Kidani, Y., Uno, S., Kato, Y., and Koike, H., Bunseki Kagaku, 1974, 23, 740. I. P., and Zolotov, Yu. A., Zh. Anal. Khim., 1976, 31, 757.TABLE V COMPARISON OF COPPER DETERMINATION BETWEEN NQT METHODS AND OTHER PROCEDURES Compound Ammonium tetramethylenedithiocarbamate Sodium diethyldithiocarbamate .. .. 8-Hydroxyquinoline . . .. .. . . Dithizone . . . . . . . . .. Acetylacetone . . .. .. .. .. Hexafluoroacetylacetone . . . . .. Thiothenoyltrifluoroacetone . . .. .. Ammonium thiocyanate . . . . .. Hexahydroazepinium hexahydroazepine- 1-caibodithioate . . .. . . Trioctylamine . . . . . . . . Potassium ethylxanthate . . .. 2-(2-Pyridylazo)naphth-l-o1 . . ' . . 4,7-Diphenyl-l,lO-phenanthroline . . 1,2-Naphthoquinone thiosemicarbazone * No information about interferences Solvent PH IBMK 4.0 Amy1 alcohol 2.5 IBMK 3-13 Chloroform 9-10 Benzene - Hexane - Propylene carbonate 1 .O Xylene 4.7 Detection limit (organic phase), p.p.m. 0.060 0.016 0.019 0.050 0.060 0.050 -0.020 0.150 Coefficient of variation, yo Interferences 3 -* 2 -* 4 -* - -* - -* * - - - - Fe, Hg, Ag, Co, Cd, Zn Fe, Hg, Zn, Mo, Co, I? Reference 24 25 26 27 28 28 29 30 !a r .. Butyl acetate 6.0 0.018 5.1 -* 31 32 cn 3.0 0.030 3.0 -* .. IBMK .. Toluene 7 kf HC1 0.080 6.6 -* 33 .. IBMK 8.5 0.060 3.2 Ni, Fe, Co, Al, Cr 34 0 .. IBMK 2.0 0.014 - Fe. Pb, Mn, Al, Sn, Hg 35 0 .. IBMK 3.5-7.1 0.020 0.96 -* This method given in the reference.518 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. SILVA AND VALCARCEL Lehane, D. P., and Werner, M., Am. J . Clin. Pathol., 1973, 59, 10. Yamamoto, Y., Kumamaru, T., and Otani, Y., Bunseki Kagaku, 1969, 18, 359. Luque de Castro, M. D., Cosano, E., Perez-Bendito, M. D., and Valcarcel, M., An. Quim., 1979, 75, Job, P., Ann. Chim., 1928, 8, 113. Irwing, H., and Pierce, T. B., J . Chem. SOC., 1959, 2565. Kenneth, M. A., Douglas, G. M., and Kenneth, W. J., Anal. Chem., 1975, 47, 1034. Tweeten, T. N., and Knoeck, J. W., Anal. Chem., 1976, 48, 64. Culp, J . H., Windham, R. L., and Whealy, R. D., Anal. Chem., 1971, 43, 1321. Iu, K. L., Pulford, I. D., and Duncan, H. J., Anal. Chim. Acta, 1979, 106, 319. Bailey, B. W., and Lo, F., Anal. Chem., 1972, 44, 1304. Masakazu, D., Takeshi, K., Kenji, Y., and Itsuo, O., Bunseki Kagaku, 1977, 26, 507. Stemphens, B. G., and Felkel, H. L., Jr., Anal. Chem., 1975, 47, 1676. Tsalev, D. L., Alimarin, I. P., and Neiman, S. I., Zh. Anal. Khim., 1972, 27, 1223. Sparks, R. W., Vita, 0. A., and Walker, C. R., Anal. Chim. Acta, 1972, 60, 222. Orlova, V. A., Spivakov, B. Ya., Shkinev, V. M., Kirillova, T. I., Ivanova, V. A., Malyutina, T. M., Aihara, M., and Kiboku, M., Bunseki Kagaku, 1975, 24, 447. Komarek, J., Havel, J., and Sommer, L., Collect. Czech. Chem. Commun., 1979, 44, 3241. Pedensen, B., Willems, M., and Jmgensen, S. S., Analyst, 1980, 105, 119. Ejaz, M., Talanta, 1981, 28, 441. 861. and Zolotov, Yu. A., Zh. Anal. Khim., 1978, 33, 91. Received July 15th, 1981 Accepted October Zlst, 1981

ISSN:0003-2654    

DOI:10.1039/AN9820700511

出版商:RSC    

年代:1982

数据来源: RSC

摘要:

Analyst, May, 1982, Vol. 107, pp. 519-524 519 Spectrophotometric Determination of Uranium(V1) in Phosphoric Acid by Means of Solvent Extraction with Mixtures of TOPO and Biphenyl Takehiro Kojima," Yasumasa Shigetomi," Hideaki Kamba" and Hirobumi Iwashiro" Taka bu mi Sa ka mot0 and Akira Doi Department of Chemistry, Okayama College of Science, Ridai-cho, Okayama 700, Japan Department of General Education, Okayama College of Science, Ridai-cho, Okayama 700, Japan Department of Applied Chemistry, Okayama College of Science, Ridai-cho, Okayama 700, Japan The variations in the distribution coefficients of twelve metals and uranium between nitric acid or hydrochloric acid - TOPO (trioctylphosphine oxide) systems have been studied as functions of the concentration of nitric acid, hydrochloric acid and TOPO and temperature (in the range 70-80 "C), employing biphenyl as the diluent for TOPO.The formula UO,(NO,),- (TOPO), can be assigned to the complex. Uranium in a phosphoric acid solution is quantitatively extracted from 2 mol dm-3 nitric acid into molten TOPO - biphenyl at about 70 "C. The organic phase separates out as a solid on cooling and is dissolved in ethanol. The uranium in this solution is then determined spectrophotometrically with 1-(2-pyridylazo)naphth-2-01. Beer's law holds in the range 1-8 p.p.m. of uranium, and the relative standard devi- ation for 10 determinations was 2.10/, . Keywords : U r a n i u m ( V I ) ; spectrophotornetry ; phosphoric a c i d ; TOPO - biphenyl mixtures ; solvent extraction The fact that phosphoric acid made by a wet process contained a considerable amount of uranium and the recovery of that uranium was not yet carried out industrially aroused our interest.lS2 As a first step to recovering it we studied the spectrophotometric determination of uranium in phosphoric acids.This determination was found to have been developed already by Pkrez-Bustamante and Delgado3 who used Arsenazo I11 as a chromogenic agent ; however, their method required the use of many kinds of masking agents, which led to complicated procedures. The present authors have investigated a solvent extraction with mixtures of trioctyl- phosphine oxide (TOPO) and naphthalene or ben~ophenone.~,~ Solvent extractions have the merits that metal ions can be efficiently concentrated by the extraction, as it can be effected with a smaller volume of solvent than in simple solvent extraction, and that upon cooling, the extraction phase separates out as a solid.As it is a simple matter to raise the extractant concentration when using TOPO, high distribution coefficients are often obtained. However, we found several faults with these extractions, such as the escape of naphthalene or the adhesion of the extraction phase to the walls of vessels, although these faults are improved to some extent by using biphenyl as a diluent. In this work, firstly, the extraction behaviour of 12 metals in the presence of biphenyl was examined in detail, and secondly, the selective extraction behaviour shown by uranium was applied to its rapid and simple determination in phosphoric acid.Experimental Reagents 0.502 g of uranyl nitrate in demineralised water and diluting to 100 em3. of other metals Standard uranium(V1) solution (2 x 10-2 mol dm-3) was prepared by dissolving Stock solutions mol dm-3) were prepared by dissolving appropriate amounts of the * Correspondence may be addressed to any of these authors.520 metal salts in 100 cm3 of the 0.1 mol dm-3 nitric acid or hydrochloric acid. reagents used were of analytical-reagent grade. KO JIMA et al. : SPECTROPHOTOMETRIC DETERMINATION OF Analyst, VoZ. 107 The other Apparatus The pH of the solution was determined by a Hitachi - Horiba H-5 pH meter. A Hitachi - Perkin-Elmer 139 spectrophotometer was used for the determination of metals. Extraction Procedure The acidity of 20 cm3 of uranium solution was adjusted and the solution transferred into a 100-cm3 Erlenmyer flask fitted with a tightly fitting stopper.Next 50mg of TOPO and 200 mg of biphenyl were added and the flask was heated on a water-bath at about 70 "C until the TOPO - biphenyl phase melted completely. After being vigorously shaken for a few minutes, the flask was removed from the bath and cooled to room temperature. The solid phase was filtered through a quantitative grade filter-paper (5A) and the uranium remaining in the aqueous phase was determined with 1-(2-pyridylazo)naphth-2-01 (PAN) .6 The extractions of the other metals were carried out in a similar manner and subsequently their determinations in the aqueous phase were carried out spectrophotometrically with appropriate chromogenic agents : for calcium( 11) , phthalein complexone ; for chromium( 111), diphenylcarbazide ; for nickel(II), dimethylglyoxime ; for aluminium( 111) and zirconium(IV), quinolin-8-01; for scandium(III), neo-thorin ; for copper(II), diethyldithiocarbamate; for iron(III), 1,lO-phenanthroline; for zinc(II), zincon; for manganese(I1) and vanadium(V), 4-(2-pyridylazo)resorcinol (PAR) ; and for cobalt (11), PAN.Determination of Uranium in Phosphoric Acid The diluted phosphoric acid, containing about 25 pg of uranium, was transferred into a 100-cm3 stoppered test-tube. This procedure was repeated for a number of tubes. The acidity was adjusted to 2 mol dm-3 with nitric acid, and appropriate amounts of uranium were added to the various tubes; each solution was then diluted to 15 cm3 with water.Next 0.5 g of the mixture of TOPO - biphenyl (1 + 4) was added to each of them, and the tubes were heated on a water-bath at about 70 "C until the TOPO -biphenyl phase had melted completely. After undergoing vigorous shaking for 1 min, each tube was removed from the bath and cooled to room temperature. Then, after rejecting the aqueous phase by decantation, the extraction phase was washed three times with 10 cm3 of 2 mol ~ m - ~ nitric acid. The extraction phase, separated by filtration through a filter-paper (5A), was dissolved in 5 cm3 of ethanol. To the resulting solution 2 cm3 of the 0.1% PAN and 1.5 cm3 of a 10% triethanolamine in ethanol solution were added and the total volume was adjusted to 10 cm3. The contents of each tube were mixed well and the absorbance of the solution at 555 nm was measured against a reagent blank.Results and Discussion Extraction Parameters The time required to reach equilibrium at 70 "C was examined by measuring the uranium concentration in the aqueous phase at different periods. In the experiments, the mixture of 20 mg of TOPO and 100 mg of biphenyl was shaken with 25 cm3 of the 1.0 x lo-* mol dm-3 uranium solution, acidified with 1 mol dm-3 nitric acid. Thirty seconds sufficed for the complete extraction of uranium, but we chose to shake for 1 min in the subsequent experi- ments. Next, the amount of biphenyl was varied from 0 to 1000 mg with TOPO kept constant at 20mg and the extraction was carried out according to the recommended procedures. The results are shown in Fig.1. The percentage extracted rises with increasing amounts of TOPO, reaches a maximum and slowly decreases with further increase of TOPO. Further, as it is difficult to separate as a solid when less than 50 mg of biphenyl are used per 20 mg of TOPO, it is preferable to extract with more than 50 mg of biphenyl. Therefore, 100 mg of biphenyl are used per 20 mg of TOPO in most instances.May, 1982 U(v1) I N PHOSPHORIC ACID BY SOLVENT EXTRACTION 521 250 500 750 1 000 Amount of biphenylhg Fig. 1. Effect of amount of biphenyl added on the extraction of uranium a t 70 "C. TOPO, 20 mg; U(VI), mol dm-3; concentration of HNO,, 1 mol dm-3; and shaking time, 1 min. Composition of Uranium(V1) Complex The coordination number of TOPO to uranium was examined.The distribution coefficients of uranium from the lo-* mol dm-3 uranium solution in the 1 mol dm-3 nitric acid are plotted as a function of the concentration of TOPO in Fig. 2. The slope of the line is approximately 2, indicating the coordination number to be 2. In Fig. 3, the distribution coefficients of uranium(V1) are plotted as a function of the concentration of nitric acid. The distribution coefficient of uranium passes through a maximum at about 0.5 mol dm-3 initial acidity. It seems that the decrease of the distribution coefficient at high acidity is caused by the fact that a uranium complex and nitric acid compete to react with TOPO. That is, the nitric acid is extracted with TOPO rather than the uranium complex as the concentration of nitric acid increases.As the slope of the line is unity at lower acidity, the complex could be UO,(TOPO),(NO,)+, although, as the species of the complex extracted must be neutral, U0,(TOPO),(N03)(OH) might be a possibility. I t is unlikely that the complex will be hydrolysed to UO,(TOPO),(NO,) (OH), judging from the low value of the constant for the r e a ~ t i o n . ~ However, as the uranium complex is extracted competing with nitric acid, and an apparent value of unity for the slope is observed, it seems reasonable to assume that the complex extracted is U0,(TOPO),(N03),. Effect of Uranium Concentration The variation of the distribution coefficient, D, was examined as a function of the uranium concentration. The amount of uranium in the organic phase increased with increasing concentration in the aqueous phase, but the distribution Therefore a maximum is observed, The results are shown in Table I.I I " 1 2 -1 0 Log(TOPO1 Fig. 2. Extraction of uranium by TOPO in biphenyl. Organic phase, 1 g ; U(VI), moI dm-3; concentration of HNO,, 1 mol dm-3; and shaking time, 1 min. 1 1 LOg[HNO,I Fig. 3. Effect of nitric acid concentration on the extraction of uranium by TOPO in biphenyl. TOPO, 50 mg; biphenyl, 100 mg; U(VI), rnol dm-3; and shaking time, 1 min.522 KOJIMA et d. : SPECTROPHOTOMETRIC DETERMIN-4TION OF Analyst, vd. I07 TABLE I EFFECT OF THE INITIAL CONCENTRATION OF URANIUM(V1) ON THE EXTRACTION MEASURED IN TERMS OF DISTRIBUTION COEFFICIENT TOPO, 20 mg; concentration of HNO,, 1 mol dm-3; shaking time, 1 min. Amount of biphenyl/mg Initial concentration of (-A-1 uranium(VI)/mol dm-3 800 3 000 1.26 x 10-4 158.4 11.2 3.16 x 10-4 112.2 7.1 6.31 x 10-4 39.8 4.5 1.38 x 10-3 11.2 3.2 2.51 x 10-3 3.9 1.9 coefficient decreased.This implies that the increase of the loading rate brings about the depression of the distribution coefficient, as is generally observed in an ion-exchange reaction. Extraction Behaviour of Thirteen Metals The extraction behaviour of metals containing uranium(V1) from 0.14 mol dm-3 nitric acid or hydrochloric acid solutions was examined. The results are shown in Tables I1 and 111. Uranium and zirconium were extracted quantitatively from both solutions, while other metals were poorly extracted from nitric acid solution, but iron(III), copper(I1) and zinc(I1) were extracted to some extent from hydrochloric acid solution.The extraction properties from nitric acid solution of the mixtures of uranium and the other metals were also investi- gated. I t was found that uranium could be separated from these metals by extraction. TABLE I1 PERCENTAGE EXTRACTION FOR METAL IONS EXTRACTED FROM NITRIC ACID SOLUTION WITH TOPO IN BIPHENYL AT 70 "C TOPO, 50 mg; biphenyl, 200 mg; metal ions, mol dm-3. Nitric acid/mol dm-3 A I -t Metal ion 0.1 0.5 1.0 2.0 3.0 4.0 Ca(I1) . . .. . . 0.0 0.0 0.0 0.0 0.0 0.0 Al(II1). . .. . . 7.8 5.2 1.0 0.0 0.0 0.0 Mn(I1). . .. . . 0.0 0.0 0.0 0.0 0.0 0.0 Sc(II1). . .. . . 89.8 76.0 52.4 30.0 - - Fe(II1) .. . . 0.0 0.0 0.0 0.0 0.0 0.0 Zn(I1) . . .. . , 0.0 0.0 0.0 0.0 0.0 0.0 Co(I1) . . .. . . 0.0 0.1 1.0 1.0 1.2 1.0 - Cr(II1).. .. . . 0.0 0.0 0.0 2.1 5.2 Ni(I1) . . .. . . 2.0 2.1 2.6 2.0 1.0 0.6 Cu(I1) . . .. . . 0.2 1.0 2.0 2.0 1.8 1.4 V(V) .. .. . . 8.0 6.1 0.5 0.0 0.0 0.0 Zr(1V) . . .. . . 89.0 95.2 97.8 98.0 99.0 99.0 U(V1) . . .. . . 98.0 99.1 99.0 99.2 98.6 98.0 Effect of Temperature The extraction of uranium was studied as a function of temperature for the TOPO - cyclohexane system.8 It is reported that the change of apparent enthalpy for the extraction, AH, was -24 kJ mol-l. The experiments were carried out in a similar manner to thqse with the TOPO - biphenyl system. Table IV shows the variation of distribution coefficients with temperature. It was found that for all values the distribution coefficients decrease with increasing temperature. The calculated average apparent AH value for the extraction reaction has been found to be -46 kJ mol-l in the range 70-80 "C. Determination of Uranium(V1) in Phosphoric Acid addition of a PAN - ethanol solution to the extraction phase dissolved in ethanol.For the spectrophotometric determination of uranium in phosphoric acids, we propose the The bestMay, 1982 U(v1) IN PHOSPHORIC ACID BY SOLVENT EXTRACTION TABLE I11 PERCENTAGE EXTRACTION FOR METAL IONS EXTRACTED FROM HYDROCHLORIC ACID SOLUTION WITH ToPo IN BIPHENYL AT 70 "c TOPO, 50 mg; biphenyl, 200 mg; metal ions, mol dm-3. 523 Metal ion Ca(I1) . . . . Cr(II1). . . . Ni(I1) . . . . Al(II1). . . . Mn(I1) .. . . Cu(I1) . . . . Sc(II1). . . . Fe( 111) . . Zn(I1) . . . . V(V) .. . . Co(I1) . . . . Zr(1V) . . . . U(V1) . . .. 7 0.1 .. 0.0 . . 0.0 . . 0.0 . . 2.0 . . 0.0 . . 0.2 . . 18.2 . . 0.6 . . 0.0 . . 0.4 . - 0.0 . . 72.1 . . 90.2 Hydrochloric acid/mol dm-3 0.5 1.0 2.0 3.0 0.0 0.0 0.0 0.0 0.8 1 .o 2.8 4.0 0.0 0.0 0.0 0.0 1.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 4.2 15.6 20.3 48.2 29.6 62.2 62.0 - 12.5 26.1 54.4 78.2 36.6 80.1 77.6 75.0 1.0 2.0 4.2 11.6 0.8 1 .o 1.4 3.2 92.0 96.1 98.9 99.5 98.9 99.2 99.8 99.8 A 7 4.0 0.0 0.0 0.0 0.0 56.0 84.8 72.0 5.0 99.7 99.8 - - - conditions for colour development are as follows. The extraction phase, 0.5 g, should con- tain 25 pg of uranium and is dissolved in 5 cm3 of ethanol. To this solution are added 1 cm3 of the 0.1% PAN - ethanol solution and 2 cm3 of the 10% triethanolamine - ethanol solution; the total volume is adjusted to 10 cm3 with ethanol. AS a condition of the extraction, 20-60 pg of uranium are needed and it is preferable to extract uranium from as dilute a phosphoric acid solution as possible.As the sample of phosphoric acid contains about 100 mg of uranium per litre, the following determination procedure (the method of standard additions) should be used. The crude phosphoric acid is diluted twenty times with water and a 4 cm3 volume, 2 cm3 of concentrated nitric acid and appropriate amounts of uranium are mixed and diluted to 15 cm3 in several 100-cm3 test- tubes with close-fitting stoppers. Next, 0.5 g of the mixture of (1 + 4) TOPO - biphenyl is added to each of them. After melting the organic phase on a water-bath at 70 "C, the extraction is carried out for 1 min. As uranium can be efficiently extracted from a nitric acid medium while other metals were poorly extracted, it is preferred to wash the organic phase with the diluted nitric acid rather than water.After removing the aqueous phase by decantation, the extraction phase is washed three times with 10 cm3 of 2 mol dm-3 nitric acid. The extraction phase, separated by filtration through a filter-paper (5A), is dissolved in 5 cm3 of ethanol. TO this solution, 2 cm3 of the 0.1% PAN and 1.5 cm3 of the 10% triethanolamine - ethanol solutions are added and the total volume is adjusted to 10 cm3. The absorbance is measured at 555 nm. I t can be seen that 4 cm3 of the diluted phosphoric acid contains about 22 pg of uranium. Therefore, the crude phosphoric acid must contain 100 mg of uranium per litre. This value agrees closely with those obtained by the Johnson and By use of these procedures, interfering ions were removed.The results are shown in Fig. 4. TABLE IV VARIATION OF DISTRIBUTION COEFFICIENTS OF URANIUM(VI) BETWEEN NITRIC ACID AND ToPo AS A FUNCTION OF TEMPERATURE Temperature/ "C A Nitric acid/ f - moldm-3 TOPO/mg 50 60 70 75 80 0.5* 50 83.2 54.9 42.6 - 28.8 2.0* 50 17.4 13.8 11.2 - 9.1 2.ot 50 - - 12.6 11.5 10.5 * Benzophenone, 5 g. t Biphenyl, 5 g; U(VI), dm-3.524 KO JIMA, SHIGETOMI, KAMBA, IWASHIRO, SAKAMOTO AND DO1 0.8 $ 0.6 m m m V m c a 0.4 +? 2 0.2 2 0 Uranium concentrationipg cm-3 Fig. 4. Calibration graph for uranium by the method of standard additions. Florence method9 and the P6rez-Bustamante and Delgado method3 in our laboratory. These methods require nine kinds of masking agent, involve complicated procedures, and take 3 h, while the proposed method needs only three washings with weak nitric acid and 30 min of standing time. If 0.05% 2-(5-bromo-2-pyridylazo)-5-diethylaminopheno1 (5-Br- PADAP) - ethanol solution is used instead of a PAN - ethanol solution, the sensitivity increases 3-fold. 1. 2. 3. 4. 5. 6. 7. 8. 9. References Hirono, S., “Recovery of Uranium from Wet-Process Phosphoric Acid,” Technical Report of Tokai Works Power Reaction and Nuclear Fuel Development Corporation, PNCT 842-75-05, May, 1975. Hurst, F. J., and Crouse, D. J., Ind. Eng. Chem. Process Des. Dev., 1974, 13, 286. PCrez-Bustamante, J. A., and Delgado, F. P., Analyst, 1971, 96, 407. Shigetomi, Y., Kojima, T., Kamba, H., and Yamamoto, Y., Anal. Chim. Acta, 1980, 116, 199. Shigetomi, Y., Kojima, T., and Kamba, H., Talanta, 1980, 22, 1079. Baltisberger, R. J., Anal. Chem., 1964, 36, 2369. Baes, C. F., Jr., and Mesmer, R. E., “The Hydrolysis of Cations,” John Wiley, New York, 1979. Heyn, A. H., and Soman, Y . D., J . Inorg. Nucl. Chem., 1964, 26, 286. Johnson, D. A., and Florence, T. M., Anal. Chim. Acta, 1971, 53, 73. Received June 29th, 1981 Accepted October 22nd, 198 1

ISSN:0003-2654    

DOI:10.1039/AN9820700519

出版商:RSC    

年代:1982

数据来源: RSC