Deshpande, S S

Joshi, A P

Lakhani, Rashmi

English

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IndianJ oumalofChemistryVol.27A, January,1988,pp.85-86RapidDeterminationofManganesebyDifferentialPulseandAlternatingCurrent(1stharmonic)PolarographyRASHMI LAKHANI, S SDESHPANDE &A P JOSHI·Departmentof Chemistry,NagpurUniversity,Nagpur440010Received24thFebruary1987,revised13thApril 1987, accept-ed12May1987Manganese(II)intraceamountshasbeendeterminedbydiffer-entialpulsepolarography(DPP)andalternatingcurrent(1sthar-monic)polarography(ACP)inO.01MLiCI andTEA+ NaOH(O.1M each)supportingelectrolytesrespectively.Manganese(Il)giveswell-defined,diffusion-controlled,reversiblewaveswith Ep of-1.472Vand -0.452VversusAg/AgCl(saturatedKCl).Linearcalibrationplotsareobtainedfrom10ppbto 10ppmandfrom50ppbto 10ppminDPP andACP respectively,theminimumdeter-minablelimitsbeing10ppband50ppbrespectively.Effectofvar-iousmetalions,whichcommonlyoccurwithMn(Il) hasalsobeenstudied.The DPP in TEA (0.2M)+NaOH (0.1M) mediumhasbeensuccessfullyusedfor thedeterminationof Mn(lI) in highspeedsteel,coalashandpharmaceuticalproducts.Many techniquesuchas strippingvoltammetryl.Z,a.c. polarography3,4and dpp5- 7 have been em-ployedfor themicrodeterminationof Mn(I1).Pres-entlywe hve useddifferentialpulsepolarographyanda.c.(1stharmonic)polarography(ACP) for thedeterminationofMn(II) atppblevel.A Metrohm-E-506polarocordwithattachedcellassemblywasusedfor recordingthepolarograms.Electrodeassemblyconsistedofadroppingmercuryelectrode(d.m.e.)asanindicatorelectrode,Ag/AgCl(saturatedKCI) asareferencelectrodeandPtmetalasanauxiliaryelectrode.All chemicalsusedwereofAR grade.Stocksolutions(0.5M) of thesupportingelectrolytewerepreparedin triply distilledwater;workingsolutions'0.1,0.05,0.01M) werepreparedbysuitabledilutions.StocksolutionofMn(II) waspreparedintriplydis-tilledwaterusingMnS04.4HzO (AR) andstandar-dized.The workingsolutioncontained150 !J.gofMn(II)/25 !J.l.All usualprecautionsof traceanalysiswereobserved.ProceduremployedinDPP ofMn(II)Lithiumchloride(2.5mI,0.1M) wastakenin thecellandtothiswasaddedthemaximasuppressortri-ton-X-100(1mI,0.001%).Thevolumewasmadeup-to 25ml.To this,Mn(II) solution(25!!l)wasadded.The solutionwascompletelydeaeratedby passingdry Nz for 15 min and the polarogramrecordedagainstheblankunderthefollowingconditions:scanrange=- 1.2 to - 2.2 V; scan rate=4 mYls;tdroP=0.8;mm/tdrop=1.0;andpulsemodulationam-plitude=10mY.ProcedureemployedinACP ofMn(If)Triethanolamine(TEA) andaqueousNaOH (2.5mI,1M each)weretakenin thecellandpolarogramrecordedundertheconditionsmentionedindifferen-tialpulsepolarographywitha.c.frequencyof 75Hzandphaseangleof 0°.Differentialpulsepolarography(DPP)A varietyof supportingelectrolytes(neutral,or-ganicandinorganicsalts)wereemployedfor record-ingdifferentialpulsepolarograms.Followingelectro-lyteswerestudiedforthispurpose:KCl (0.1Mto 0.01M);NaOAc (0.1Mto 0.01M) NH4CI (0.1Mto 0.01M),KN03(0.1 Mto 0.01M),trisodiumcitrate(0.2Mto0.05M);d!sodiumtartrate(0.2Mto 0.05M);Na-oxalate(0.1MtoO.01M);Na-succinate(0.1MtoO.01M); Na-salicylate(0.1Mto 0.01M); LiCl (0.1Mto0.01M)andsodiumdihydrogenphosphate(0.1Mto0.01M).Amongstthese,LiCI solution(0.01M) wasfoundtobemostsuitableasitgavesmoothbaseline,symmet-ric,reversible,diffusion-controlledpeakswithevenlyrisingsteps,andhighercurrentvaluesandhighre-producibility.The presenceof Triton-X-100 (4x 10-5%) wasfoundtogiveimprovedbaselineandpeaksymmetryascomparedtoothersandhencewasusedasthemax-imumsuppressor.Current-concentrationrelationshipwasfoundtobelinearinthreeconcentrationranges:10ppbto100ppb,0.1ppmto 1.0ppm,and1ppmto 10ppm.Theminimumdeterminablelimitwasfoundtobe10ppb.Amongstthevariousionsstudiedfor interferencestudyZn(II),Cd(I1)andCu(I1)couldbetoleratedup-to a ratio of 1:25,Pb(II) upto 1:20while Co(II),Mo(VI) toleratedupto1:10andV(V) upto1:5only.lron(III) andCr(III) interferedseriouslyin thedeter-minationof Mn(II). However,interferencedue toFe(III)andCr(III) couldbeovercomebyusing0.2MTEA +0.1MNaOHasthesupportingelectrolyteinwhichMn(I1),Fe(III)andCr(III) peakswerewellsepa-ratedwithpeakpotentialscorrespondingto - 0.476V, -1.316Vand -0.998Vrespectively.Linearcali-brationplotsofMn(II) in therangeof 0.1ppmto 10ppmwerealsoobtainedin TEA +NaOH medium.Therecordingparametersforthisparticularsupport-ingelectrolytewereasfollows:scanrange- 0.2to- 1.7V;scanrate=6mV/s;tdrop=0.8,mm/tdrop=1;andpulsemodulationamplitude=40mY.85INDIAN 1.CHEM., VOL. 27A, JANUARY 1988TableI..-DeterminationfMn(II)inHighSpeedSteelandCoalAshSamples[Highspeedsteelcontains0.27g%Mn(II)]Sample Wt of Mn(lI) (g%)12DPP Method ACP MethodA B A BHighspeedsteelsamples(BCS)*0.2717 0.2634 0.285 0.2700.2751 0.2746 0.270 0.260dropsofHzSO 4 wereaddedtotheseandvolumewasmadeupto25mIwithtriplydistilledwater.Thecon-tentswereheatedfor 3-4hI',cooled,filteredandthefiltrateevaporatedto dryness.The residuewasdis-solvedin triplydistilledwater(25mI).An aliquot(1mI)fromthiswasplacedin thecellandthepolaro-gram recordedin TEA + NaOH medium.TheamountsofMn(II)/tabletwerefoundtobeO.3531mgand 0.35mgby calibrationandstandardadditionmethodrespectively(literature,0.355mg/tablet).Coalashsamples(wtof Mn(lI) mg/gcoalash)1 RamkrishnaGodavariValleyooalfield(AP)t 0.160 0.156 0.158 0.1542 Bhatadicoalfield,Wardhal(MS)"" 0.048 0.0487 0.049 0.050(A) Calib~ation method; (B) standard addition method* RMD:1.p8%;t RMD:1.273%;and"" RMD:1.175%The IJ1.ethodevelopedusingTEA+ NaOH wasfurther$tendedfor thedeterminationof Mn(II) inhighsp4d steel,coalashandpharmaceuticalpro-ducts.Determin.ationofMri..,IJ) in highspeedsteelbyDPPSteelsfllllple(0.3g)wastreatedwith25%HZS04(50mI)apdthesolutionwarmedgentlytillhydrogenevolutiOI)ceased.The contentswere cooled andHzOz (IQOmI)wasaddedtooxidizeanycarbideresi-due.TheisolutionwasboiledtoexpelexcessofHzOz,cooledaJjldthevolumemadeupto100mIwithtriplydistilledwater8.The polarogramswererecordedinTEA +rjJaOHmediumwith1mIand2mIaliquotsofsamples<)lution.TheamountofMn(II)wascomputedfrom cali\brationplotsandascertainedby standardadditionImethod.The resultsarepresentedin theTable1.DetermiJ1ationofMn(/J) in coalashbyDPPToa w~ighedquantityof coalashwereadded1:1HCl (25JjnI)+ conc.HN03 (1mI)andheatedtodis-solveas~andto expelacid.This procedurewasre-peat dt\fo-thre timesandfinallyth volumewasmadeuptp25mlwithtriplydistilledwater.Thepolar-ograms~ererecordedinTEA + NaOH supportingelectroly~with1mlto2mlaliquotsofthesampleso-lution.Tl)econcentrationof Mn(II) wasdeterminedbyreferringtothecalibrationcurveandascertainedbystandardadditionmethod.TheresultsaregiveninTable1.Delermifl(.llionofMn(If) in drugsby DPPCyltab,;avitamineraltablet(Dupher-InterfranLtd)wasanaly~edfor Mn(ll) content.TotalS tabletsweretakeninabeaker.Hydrochloricacid(10ml)andafew86Alternating current(Ist harmonic)polarography(ACP)A varietyofelectrolytes(alkaline,neutralcomplex-ingagentsandbuffers)weretriedasbackgroundelec-trolytesforMn(II) analysis.ThecurrentresponseandpeaksymmetrywereobservedtobethebestinTEA+ NaOH with relativelylowercurrentvalue.Thesupportingelectrolytestudiedwere:KCI(0.5 M to0.01M);Na-succinate(0.1mto0.01M);KN03 (0.1MtoO.01M);NH40H +NH4 succinate(0.1Meach);NH40H (0.1 M)+ citric acid (0.05 M); NH40H(0.1M), tartaric acid (0.1 M); and TEA (0.1M)+NaOH(O.1M).Calibrationplotsobtainedfor Mn(II) in TEA +NaOH mediumwerelinearin theMn(ll) concentra-tionrangeof50ppbto10ppm.Thelowestdetermin-ablelimitwas50ppbwithrelativemeandeviationof1.13%.Amongstthenumberofdiverseionsstudiedforin-terferencestudies,Cu(II), Co(II), Ni(II), Pb(II) andZn(II)couldbetolerateduptotheratios1:10,1:5,1:7,1:3and 1:7ratiosrespectivelywhileCd(II), Fe(III)andCr(IlI) couldbetolerateduptoaratio1:25only.The resultsof determinationofMn(II) inhighspeedsteel,andcoalashusinga.c.polarographyarepre-sentedin Table1.The authorsaregratefulto AlexandervonHum-boldtFoundation,WestGermanyforthedonationofaMetrohmpolarograph.Oneof theauthors(SSD)isgratefultoUGC, NewDelhifor theawardofajuniorresearchfellowship.References1 O'HalloranRl, Anal chimActa, 140(1982)51.2 TrojonekA & OpekarF, Anal chimActa,126(1981)15.3 SisterYu D, PolarografiaV tokhAnalyzeKishinev(1979)42.ChemAbstr,No. 101458q,Vol:91 1979.4 ZabeskiJ & StochA, ChemAnal, 18(1973)951.5 IgarashiK, MotsunagaK. Abe K, Kudo J, FukaseS & YanadoM. Hakkaido DiagakuSuisangakubuKenkyu fho, 34(1983)30.ChgemAhstr,132919k,Vol:99,1983.() WisserK& WoehrleG, MikrochimActa,5 (1980)129.7 De GalenL, EnkelumC. longeriusC etal" FreseniusZ analchol/, 264 (1973) 173.Chol/ Ahstr, 26834fVol: 79,1973.K Gholse S 13,Deshmukh 13K & Anokar P J, } llldii/ll c/1('f1/Soc,62 (19K'+)-+M.

Rapid Determination of Manganese by Differential Pulse and Alternating Current (1st harmonic) Polarography

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Rapid Determination of Manganese by Differential Pulse and Alternating Current (1st harmonic) Polarography

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