聯合國糧農組織FAO/世界衛生組織WH亞鐵氰化鈣、亞鐵氰化鉀和亞鐵氰化鈉規格化學名稱亞鐵氰化鈣（或鉀或鈉）,檢驗FERROCYANIDESofCALCIUM,POTASSIUMandSODIUMPreparedatthe17thJECFA(1973),publishedinFNP4(1978)andinFNP52(1992).Metalsandarsenicspecificationsrevisedatthe57thJECFA(2001).AnADIof0-0.025mg/kgbwwasestablishedatthe18thJECFA(1974)SYNONYMSYellowprussiateoflime,potashorsoda;hexacyanoferrateofcalcium,potassiumorsodium;INSNo.Calciumsalt538,Potassiumsalt536,Sodiumsalt535ChemicalnamesCalcium(orPotassiumorSodium)ferrocyanide,Calcium(orPotassiumorSodium)hexacyanoferrate(II)C.A.S.number1327-39-5,Calciumsalt13943-58-3,Potassiumsalt13601-19-9,SodiumsaltFormulaweightCalciumsalt508.3Potassiumsalt422.4Sodiumsalt484.1AssayNotlessthan99.0%oftherespectiveferrocyanideDESCRIPTIONYellowcrystalsorcrystallinepowderFUNCTIONALUSESAnticakingagentSolubleinwater;potassiumandsodiumsaltsareinsolubleinethanolTestforferrocyaniTo10mlofa1%solutionofthesampleadd1mlofferricchlorideTS.Adarkblueprecipitateisformed.(RetainthemixturefortheTestforcalcium).PassestestTestthemixturefromtheTestforferrocyanideTestforpotassiumPassestestPassestestNotdetectableDissolve10mgofcoppersulfateinamixtureof8mlofwaterand2mlofammoniaTS.Wetastripoffilterpaperwiththissolution,andplacethewetpaperinastreamofhydrogensulfide.Whenonedropofa1%solutionofthesampleisplacedonthebrownreagentpaper,awhitecircleshouldnotbeproduced.NotdetectableDissolveabout10mgofthesamplein10mlofwaterandplaceonedropofthissolutiononaspotplate.Addonedropofa1%solutionofleadnitrate,followedbyafewdropsofasolutionpreparedbysaturatingcold2Naceticacidwithbenzidine.Noblueprecipitateorbluecolorationshouldappear.Notmorethan3mg/kg(MethodII)Notmorethan5mg/kgDetermineusinganatomicabsorptiontechniqueappropriatetothespecifiedlevel.TheselectionofsamplesizeandmethodofsamplepreparationmaybebasedontheprinciplesofthemethoddescribedinVolume4,“InstrumentalMethods.”Weigh3gofthesampletothenearest0.1mgandtransferintoa400-mlbeaker.Dissolvein225mlofwater,andaddcautiouslyabout25mlofsulfuricacidTS.Add,withstirring,1dropoforthophenanthrolineTS,andtitratewith0.1Ncericsulfateuntilthecolourchangessharplyfromorangetopure