aoac官方方法920.35煙草制品中的尼古丁硅鎢酸的方法_第1頁
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1、7.5.16AOACOfficialMethod920.35NicotineinTobaccoProductsSilicotungsticAcidMethodFirstAction1920FinalActionA.ReagentSilicotungsticacidsolution.—Dissolve120gsilicotungsticacid(4H2O?SiO2?12WO3?22H2OSiO2?12WO3?6H2O)inH2Odilut

2、eto1L.(Acidshouldbewhitepaleyellowcrystalsfreefromgreencolsolutionshouldbefreefromcloudinessgreencol.Oftheseveralsilicotungsticacids4H2O?SiO2?10WO3?3H2O4H2O?SiO2?12WO3?20H2Odonotgivecrystallineprecipitateswithnicotinesho

3、uldnotbeused.)B.DeterminationWeightestptioncontainingpreferably0.1–1.0gnicotine.Iftestsamplecontainsverylittlenicotine(ca0.1%)donotincreaseamounttopointwhereitinterfereswithdistillation.WashwithH2Ointo500mLKjeldahlflaski

4、fnecessaryaddlittleparaffintopreventfrothingfewsmallpiecespumicetopreventbumping.Add10gNaCl10mLNaOHsolution(30%byweight)closeflaskwithrubberstopperthroughwhichpassesstemoftrapbulbinlettubefsteam.Connecttrapbulbtowellcool

5、edcondenserlowerendofwhichdipsbelowsurfaceof10mLHCl(14)insuitablereceivingflask.Steamdistilrapidly.Whendistillationiswellunderwayheatflasktoreducevolumeofliquidasfaraspracticablewithoutbumpingexcessiveseparationofinsolub

6、lematter.DistiluntilfewmLdistillateshowsnocloudopalescencewhentreatedwithsilicotungsticacidsolutionHCl(14).Confirmalkalinityofresidueindistillationflaskwithphenolphthalein.Adjustdistillatewhichmaytotal1.0–1.5Ltoconvenien

7、texactvolume(solutionmaybeconcentratedonsteambathwithoutlossofnicotine)mixwellpassthroughdryfilterifnotclear.Testdistillatewithmethylangetoconfirmacidity.Pipetaliquotcontainingca0.1gnicotineintobeaker.(Iftestsamplesconta

8、inverysmallamountsofnicotinealiquotcontainingaslittleas0.01gnicotinemaybeused.)Toeach100mLliquidadd3mLHCl(14)1mLsilicotungsticacidfeach0.01gnicotinesupposedtobepresent.Stirthoughlyletstovernightatroomtemperature.Befefilt

9、eringstirprecipitatetoseethatitsettlesquicklyisincrystallinefm.FilteroneitherashlesspaperGoochwashwithHCl(11000)atroomtemperature.Continuewashingf23fillingsoffilterafternomeopalescenceappearswhenfewmLfreshfiltrateistreat

10、edwithfewsnicotinedistillate.WithpapertransferpaperprecipitatetoweighedPtcrucibledrycarefullyigniteuntilallCisdestroyed.FinallyheatoverMekerburner≤10min.Weightresidue0.1141=weightnicotineinaliquot.WithGoochdryinoven3hat1

11、05Cweigh.Weightresidue0.1012=weightnicotineinaliquot.Reference:USDABur.AnimalInd.Bull.133.CAS54115(nicotine)?2000AOACINTERNATIONAL7.5.16AOACOfficialMethod920.35NicotineinTobaccoProductsSilicotungsticAcidMethodFirstAction

12、1920FinalActionA.ReagentSilicotungsticacidsolution.—Dissolve120gsilicotungsticacid(4H2O?SiO2?12WO3?22H2OSiO2?12WO3?6H2O)inH2Odiluteto1L.(Acidshouldbewhitepaleyellowcrystalsfreefromgreencolsolutionshouldbefreefromcloudine

13、ssgreencol.Oftheseveralsilicotungsticacids4H2O?SiO2?10WO3?3H2O4H2O?SiO2?12WO3?20H2Odonotgivecrystallineprecipitateswithnicotineshouldnotbeused.)B.DeterminationWeightestptioncontainingpreferably0.1–1.0gnicotine.Iftestsamp

14、lecontainsverylittlenicotine(ca0.1%)donotincreaseamounttopointwhereitinterfereswithdistillation.WashwithH2Ointo500mLKjeldahlflaskifnecessaryaddlittleparaffintopreventfrothingfewsmallpiecespumicetopreventbumping.Add10gNaC

15、l10mLNaOHsolution(30%byweight)closeflaskwithrubberstopperthroughwhichpassesstemoftrapbulbinlettubefsteam.Connecttrapbulbtowellcooledcondenserlowerendofwhichdipsbelowsurfaceof10mLHCl(14)insuitablereceivingflask.Steamdisti

16、lrapidly.Whendistillationiswellunderwayheatflasktoreducevolumeofliquidasfaraspracticablewithoutbumpingexcessiveseparationofinsolublematter.DistiluntilfewmLdistillateshowsnocloudopalescencewhentreatedwithsilicotungsticaci

17、dsolutionHCl(14).Confirmalkalinityofresidueindistillationflaskwithphenolphthalein.Adjustdistillatewhichmaytotal1.0–1.5Ltoconvenientexactvolume(solutionmaybeconcentratedonsteambathwithoutlossofnicotine)mixwellpassthroughd

18、ryfilterifnotclear.Testdistillatewithmethylangetoconfirmacidity.Pipetaliquotcontainingca0.1gnicotineintobeaker.(Iftestsamplescontainverysmallamountsofnicotinealiquotcontainingaslittleas0.01gnicotinemaybeused.)Toeach100mL

19、liquidadd3mLHCl(14)1mLsilicotungsticacidfeach0.01gnicotinesupposedtobepresent.Stirthoughlyletstovernightatroomtemperature.Befefilteringstirprecipitatetoseethatitsettlesquicklyisincrystallinefm.FilteroneitherashlesspaperG

20、oochwashwithHCl(11000)atroomtemperature.Continuewashingf23fillingsoffilterafternomeopalescenceappearswhenfewmLfreshfiltrateistreatedwithfewsnicotinedistillate.WithpapertransferpaperprecipitatetoweighedPtcrucibledrycarefu

21、llyigniteuntilallCisdestroyed.FinallyheatoverMekerburner≤10min.Weightresidue0.1141=weightnicotineinaliquot.WithGoochdryinoven3hat105Cweigh.Weightresidue0.1012=weightnicotineinaliquot.Reference:USDABur.AnimalInd.Bull.133.

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