ReadilyCarbonizableSubstancesTest
Theseimpuritiesaremostlycompoundsofunknownstructure,andtheircontentcan beeasilycontrolledbythemethodofsulfuricacidcoloring.TheUnitedStates PharmacopoeiaandtheJapanesePharmacyBureauformulafortheexaminationof readilycarbonizablesubstancesisbasicallythesame,allusingvisualcolorimetric method
ReadilyCarbonizableSubstancesTestMethod
Taketwocolorimetrictubeswiththesameinnerdiameter,add5mLofthecontrol solutionundereachspeciesintubeA;add5mLofsulfuricacidintubeB,andslowly addthespecifiedamountofthetestarticleinstagesPlacetubeAandBtogetherin frontofawhitebackground.Observewithaflatview,thecolorshownintubeBshall notbedarkerthantubeA.Ifthetestproductisasolid,youshouldfirstbegroundinto afinepowder.Ifyouneedtoheattodissolve,youcantakethetestandsulfuricacid mixedwell,heatedanddissolved,cooled,andthenmovedintothecolorimetrictube.
Therearethreemaintypesofcontrolsolution:thestandardcolorimetricsolutionof differentshadesunder"colorcheckofsolution";thecontrolsolutionpreparedbythe colorimetricsolutionofdiamondchloride,colorimetricsolutionofpotassium diphosphateandcolorimetricsolutionofcoppersulfateaccordingtotheprescribed method;potassiumpermanganatesolution
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