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1、CALCIUMDIHYDROGENDIPHOSPHATENewspecificationspreparedatthe57thJECFA(2001)andpublishedinFNP52Add9(2001).NoADI,butagroupMTDIof70mg/kgbw,expressedasthphosphorusfromallfoodsources,wasestablishedatthe26JECFA(1982).SYNONYMSAcidcalciumpyrophosphate,monocalciumdih
2、ydrogenpyrophosphate;INSNo.450(vii)DEFINITIONChemicalnamesMonocalciumdihydrogendiphosphateC.A.S.number14866-19-4ChemicalformulaCaH2P2O7Formulaweight215.97AssayNotmorethan64%expressedasP2O5ondriedbasis.DESCRIPTIONWhitecrystalsorpowderFUNCTIONALUSESStabilize
3、r,leaveningagent,emulsifier,nutrientCHARACTERISTICSIDENTIFICATIONTestforcalcium(Vol.4)PassestestTestforphosphatePassestest(Vol.4)PURITYLossondrying(Vol.4)Anhydrous:Notmorethan1%(105°,4h)AcidinsolublematterNotmorethan0.4%(Vol.4)Fluoride(Vol.4)Notmorethan30m
4、g/kgMethodIII;useanappropriatesamplesizeandappropriatevolumesofstandardsolutionforconstructionofthecalibrationcurve.Arsenic(Vol.4)Notmorethan3mg/kgLead(Vol.4)Notmorethan4mg/kgDetermineusinganatomicabsorptiontechniqueappropriatetothespecifiedlevel.Theselect
5、ionofsamplesizeandmethodofsamplepreparationmaybebasedontheprinciplesofthemethoddescribedinVolume4,“InstrumentalMethods.”METHODOFWeighaccuratelyabout200mgofthesample,dissolvein25mlofwaterandASSAY10mlofdilutednitricacidTSandboilfor30min.Filterifnecessary,and
6、washanyprecipitate,thendissolvetheprecipitatebytheadditionof1mldilutedonitricacidTS.Adjustthetemperaturetoabout50,add75mlofammoniumomolybdateTS,andmaintainthetemperatureatabout50for30min,stirringoccasionally.Allowtostandfor16horovernightatroomtemperature.D
7、ecantthesupernate,throughafilterpaper,washtheprecipitateonceortwicewithwaterbydecantationusing30to40mleachtime,andpourthewashingsthroughthesamefilter.Transfertheprecipitatetothesamefilter,andwashwithpotassiumnitratesolution(1in100)untilthefiltrateisnolonge
8、racidtolitmuspaper.Transfertheprecipitatewithfilterpapertotheoriginalprecipitationvessel,add50.0mlof1Nsodiumhydroxide,agitateuntiltheprecipitateisdissolved,add3dropsofphenolphthaleinTSandtitratetheexcessalkal
