美國(guó)藥典無(wú)水乙醇標(biāo)準(zhǔn)

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Acidityoralkalinity—

Phenolphthaleinsolution—Dissolve0.1gofphenolphthaleinin80mLofalcohol,anddilutewithwaterto100mL.

Procedure—To20mLofalcohol,add20mLoffreshlyboiledandcooledwaterand0.1mLofPhenolphthaleinsolution.Thesolutioniscolorless.Add1.0mLof0.01Nsodiumhydroxide.Thesolutionispink(30ppm,expressedasaceticacid).

Ultravioletabsorption—RecordtheUVabsorptionspectrumofthetestmaterialfrom200to400nmina5-cmcell:maximumabsorbance0.40at240nm,0.30between250and260nm,and0.10between270and340nm.Examinebetween235and340nm,ina5-cmcell,usingwaterasthecompensationliquid.Theabsorptioncurveissmooth.Volatileimpurities—

TestsolutionA:substancetobeexamined.

TestsolutionB—Add150Lof4-methylpentan-2-olto500.0mLofthesubstancetobeexamined.

StandardsolutionA—Dilute100Lofmethanolwiththesubstancetobeexaminedto50.0mL.Dilute5.0mLofthesolutionwiththesubstancetobeexaminedto50.0mL.StandardsolutionB—Dilute50Lofmethanoland50Lofacetaldehydewiththe

substancetobeexaminedto50.0mL.Dilute100Lofthesolutionwiththesubstancetobeexaminedto10.0mL.

StandardsolutionC—Dilute150Lofacetalwiththesubstancetobeexaminedto50.0mL.Dilute100Lofthesolutionwiththesubstancetobeexaminedto10.0mL.

StandardsolutionD—Dilute100Lofbenzenewiththesubstancetobeexaminedto100.0mL.Dilute100Lofthesolutionwiththesubstancetobeexaminedto50.0mL.Chromatographicsystem(see)—Thegaschromatographisequippedwithaflame-ionizationdetector,maintainedatabout280,anda0.32-mm30-mfusedsilicacapillarycolumnbondedwitha1.8-mlayerofphaseG43.Thecarriergasisheliumwithalinearvelocityofabout35cmpersecondandasplitratioof1:20.Thecolumntemperatureismaintainedat40forthefirst12minutesafteraninjectionismadeandisincreasedfrom40to240from12to32minutesafterinjection.Duringtheperiodof32to42minutesafteraninjectionismadethecolumntemperatureismaintainedat240.Theinjectionporttemperatureismaintainedat200.ChromatographStandardsolutionB,andrecordthepeakresponsesasdirectedforProcedure:theresolution,R,betweenthefirstmajorpeak(acetaldehyde)andthesecondmajorpeak(methanol)isnotlessthan1.5.

Procedure—Separatelyinjectequalvolumes(1.0L)of

TestsolutionA,TestsolutionB,

StandardsolutionA,StandardsolutionC,andStandardsolutionDintothe

chromatograph,recordthechromatograms,andmeasurethemajorpeaks.CalculatetheconcentrationofmethanolinTestsolutionA:notmorethanhalftheareaofthe

correspondingpeakinthechromatogramobtainedwithStandardsolutionA(200ppm).Calculatethesumofthecontentsofacetaldehydeandacetal,expressedas

acetaldehyde,usingthefollowingformula:

[(10AE)/(AT–AE)]+[(30CE)/(CT–CE)]

inwhichAEistheareaoftheacetaldehydepeakinthechromatogramobtainedwithTestsolutionA;ATistheareaoftheacetaldehydepeakinthechromatogramobtainedwithStandardsolutionB;CEistheareaoftheacetalpeakinthechromatogramobtainedwithTestsolutionA;andCTistheareaoftheacetalpeakinthechromatogramobtainedwithStandardsolutionC:notmorethan10ppm,expressedasacetaldehydeisfound.Calculatethecontentofbenzeneusingthefollowingformula:

(2BE)/(BT–BE)

inwhichBEistheareaofthebenzenepeakinthechromatogramobtainedwithTestsolutionA,andBTistheareaofthebenzenepeakinthechromatogramobtainedwithStandardsolutionD:notmorethan2ppmisfound.Ifnecessary,theidentityofbenzenecanbeconfirmedusinganothersuitablechromatographicsystem(stationaryphasewithadifferentpolarity).

ThetotalofallotherimpuritiesinthechromatogramobtainedwithTestsolutionBisnotmorethantheareaofthepeakdueto4-methylpentan-2-olinthechromatogramobtainedwithTestsolutionB(300ppm).Disregardanypeaksthatare0.03timestheareaofthepeakcorrespondingto4-methylpentan-2-olinthechromatogramobtainedwithTestsolutionB(9ppm).

Limitofnonvolatileresidue—Evaporate100mLinatareddishonawaterbath,anddryat100to105for1hour:theweightoftheresiduedoesnotexceed2.5mg.

AuxiliaryInformation—Pleasebefo