AlfacalcidolEUROPEANPHARMACOPOEIA8.0Limits:01/2014:1286–impuritiesA,B:foreachimpurity,notmorethantheALFACALCIDOLareaoftheprincipalpeakinthechromatogramobtainedwithreferencesolution(a)(0.5percent)andnotmorethanoneofthepeakshasanareagreaterthantheareaAlfacalcidolumoftheprincipalpeakinthechromatogramobtainedwithreferencesolution(b)(0.2percent);–total:notmorethantwicetheareaoftheprincipalpeakinthechromatogramobtainedwithreferencesolution(a)(1percent);–disregardlimit:theareaoftheprincipalpeakinthechromatogramobtainedwithreferencesolution(c)(0.05percent).Water(2.5.12):maximum5.0percent,determinedon0.500g.Sulfatedash(2.4.14):maximum0.1percent,determinedon1.0g.CHOM400.6[41294-56-8]27442rASSAYDEFINITION(5Z,7E)-9,10-Secocholesta-5,7,10(19)-triene-1α,3β-diol.Dissolve0.300gbystirringin70mLofaceticanhydrideRfor1min.Titratewith0.1MperchloricaciduntilthecolourContent:97.0percentto102.0percent.changesfromviolet-bluetogreenish-blue,using0.1mLofAreversibleisomerisationtopre-alfacalcidoltakesplaceincrystalvioletsolutionRasindicator.solution,dependingontemperatureandtime.Theactivityisduetobothcompounds(seeAssay).1mLof0.1Mperchloricacidisequivalentto36.9mgofCHClNO.CHARACTERS4450242Appearance:whiteoralmostwhitecrystals.STORAGESolubility:practicallyinsolubleinwater,freelysolubleinethanol(96percent),solubleinfattyoils.Inanairtightcontainerundernitrogen,protectedfromlight,atatemperatureof2°Cto8°C.Itissensitivetoair,heatandlight.IDENTIFICATIONIMPURITIESA.Infraredabsorptionspectrophotometry(2.2.24).Specifiedimpurities:A,B.Comparison:Ph.Eur.referencespectrumofalfacalcidol.B.Examinethechromatogramsobtainedinthetestforrelatedsubstances.Results:theprincipalpeakinthechromatogramobtainedwiththetestsolutionissimilarinretentiontimeandsizetotheprincipalpeakinthechromatogramobtainedwithreferencesolution(a).TESTSRelatedsubstances.Liquidchromatography(2.2.29):usethenormalisationprocedure.Carryoutthetestasrapidlyaspossible,avoidingexposuretolightandair.Tests