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1、METHOD9014TITRIMETRICANDMANUALSPECTROPHOTOMETRICDETERMINATIVEMETHODSFORCYANIDE1.0SCOPEANDAPPLICATION1.1Thismethodcanbeusedformeasuringfree(non-complexed)cyanideandhydrocyanicacidindrinkingwater,naturalsurfacewaters,domesticandindustrialwastewaters,andinsoilextracts.Thismethodmaya
2、lsobeusedasadeterminativestepforquantifyingtotalandamenablecyanideinthealkalinedistillatesfromMethod9010.1.2Thetitrationprocedureusingsilvernitratewithp-dimethylamino-benzal-rhodanineindicatorisusedformeasuringconcentrationsofcyanideexceeding0.1mg/L(0.025mg/250mLofabsorbingliquid
3、).1.3Thecolorimetricprocedureisusedforconcentrationsbelow1mg/Lofcyanideandissensitivetoabout0.02mg/L.2.0SUMMARYOFMETHOD2.1Inthecolorimetricmeasurement,thecyanideisconvertedtocyanogenchloride(CNCl)byreactionofcyanidewithchloramine-TatapHlessthan8.Afterthereactioniscomplete,coloris
4、formedontheadditionofpyridine-barbituricacidreagent.Theabsorbanceisreadat578nmforthecomplexformedwithpyridine-barbituricacidreagentandCNCl.Toobtaincolorsofcomparableintensity,itisessentialtohavethesamesaltcontentinboththesampleandthestandards.2.2Thetitrationmeasurementusesastanda
5、rdsolutionofsilvernitratetotitratecyanideinthepresenceofasilversensitiveindicator.3.0INTERFERENCES3.1InterferencesareeliminatedorreducedbyusingthedistillationprocedureprovidedinMethod9010.3.2RefertoMethod9010foradiscussionofpotentialcyanideinterferences.4.0APPARATUSANDMATERIALS4.
6、1Spectrophotometer-Suitableformeasurementsat578nmwitha1.0cmcellorlarger.4.2Hotplatestirrer/heatingmantle.4.3pHmeter.4.4Refrigerator.CD-ROM9014-1Revision0December19964.55mLmicroburette.4.6ClassAvolumetricflasks-1000,250,and100mL.4.7Erlenmeyerflask-500mL.5.0REAGENTS5.1Reagentgradec
7、hemicalsshallbeusedinalltests.Unlessotherwiseindicated,itisintendedthatallreagentsshallconformtothespecificationsoftheCommitteeonAnalyticalReagentsoftheAmericanChemicalSociety,wheresuchspecificationsareavailable.Othergradesmaybeused,provideditisfirstascertainedthatthereagentisofs
8、ufficientlyhighpuritytopermititsusewitho
