4211 AOAC Official Method 200111 Protein(Crude)in.pdf
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4.2.11tionproceduresmustbeusedinordertoincludeNfromnitrate.)TheAOACOfficialMethod2001.11amountofproteininmostmaterialsiscalculatedbymultiplying%NProtein(Crude)inAnimalFeed,by6.25,becausemostproteinscontain16%N.Forage(PlantTissue),Grain,andOilseedsTheH2SO4andNaOHusedareinconcentratedformandareBlockDigestionMethodUsingCopperCatalysthighlycorrosive.WearglovesandeyeprotectionwhilehandlingtheandSteamDistillationintoBoricAcidchemicals.DonotmixconcentratedacidandNaOHdirectly.IfFirstAction2001chemicalsaresplashedontheskinorintheeyes,flushwithcopious[Applicabletothedeterminationof0.5–50%KjeldahlNamountsofwater.Seekmedicalattention.Donotbreathethesulfur(3–300%equivalentcrudeprotein)inforage,animalfeedandpetoxidefumesproducedduringdigestion.food,grain,andoilseeds,andapplicabletothesamematrixesasB.Apparatus976.05(4.2.05),976.06(4.2.06),984.13(4.2.09),988.05(4.2.03),(a)Digestionblock.—Aluminumalloyblockwithadjustableand990.02(4.2.07);themethoddoesnotmeasureoxidizedformsoftemperaturedeviceformeasuringandcontrollingblocktemperatureNorheterocyclicNcompounds.](TecatorDigestionSystem20,1015Digestor,FossNorthAmerica,SeeTables2001.11AandBfortheresultsoftheinterlaboratory7682ExecutiveDr,EdenPrairie,MN55344,USA;study,expressedonaproteinbasis(N×6.25),supportingaccep-+1-952-974-9892,Fax:+1-952-974-9823,tanceofthemethod.info@fossnorthamerica.com;orequivalent).A.Principle(b)Digestiontubes.—250mL.(c)Distillationunits.—(1)Forsteamdistillation.—FossThematerialisdigestedinHSOtoconverttheproteinNto24Tecator2200,orequivalent,toaccept250mLdigestiontubesand(NH)SOataboilingpointelevatedbytheadditionofKSOwith42424500mLtitrationflasks.(2)ForsteamdistillationandaCucatalysttoenhancethereactionrate.Ammoniaisliberatedbyautotitration.—FossTecator2300,orequivalent.alkalinesteamdistillationandquantifiedtitrimetricallywithstan-(d)Titrationflask.—500mLgraduatedErlenmeyerflask(fordardizedacid.Aluminumblockheatersincreasetheefficiencyofthecollectionandtitrationofdistillate).digestion.