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1、METHOD8033ACETONITRILEBYGASCHROMATOGRAPHYWITHNITROGEN-PHOSPHORUSDETECTION1.0SCOPEANDAPPLICATION1.1Method8033maybeusedtodeterminetheconcentrationofacetonitrile(CASNo.75-05-8)inaqueousmatrices.1.2Themethoddetectionlimitinwaterisapproximately1.7to2.8picograms(1.7to2.8μg/Lwitha1
2、μLinjection)at40and20voltsoffset,respectively.Theupperlimitoftherangeisapproximately5000μg/Landislimitedbythenon-linearityofthenitrogen-phosphorusdetector(NPD).Therangemaybeextendedbydilutingthesample.Thisproceduremaybeapplicabletoothermatriceswherethetargetcompoundcanbeextr
3、actedintowater.1.3ThismethodisalsoapplicabletoaqueouscondensatecollectedfromtheVOSTorsemi-VOSTsamplingtrains.1.4Thismethodisrestrictedtousebyorunderthesupervisionofanalystsexperiencedintheuseofgaschromatographsandskilledintheinterpretationofgaschromatograms.Eachanalystmustde
4、monstratetheabilitytogenerateacceptableresultswiththismethod.2.0SUMMARYOFMETHODWatersamplescontainingacetonitrileareintroducedintoaGC/NPDusingcoolon-columndirectaqueousinjection.TheGC/NPDsystemisexternallycalibratedusingaseriesofacetonitrilestandardsdilutedinorganic-freereag
5、entwater.Aseriesofblankorganic-freereagentwatersamplesaredirectlyinjecteduntilnopeaksareobservedinthechromatogram.Theacetonitrileconcentrationisquantitatedusingtheexternalcalibrationmethod.3.0INTERFERENCES3.1Therearenoknownchromatographicinterferantswhensamplesareanalyzedusi
6、ngtheoptimumoperatingconditions.However,atcolumntemperaturesgreaterthan60EC,waterbecomesaninterferant,asitcoeluteswithacetonitrileandproducesanegativedisruptionofthebaseline,therebypreventingaccuratequantitations.Thisproblemiseliminatedbyoperatingthecolumnat35EC.Atthistemper
7、ature,waterwilleventuallyeluteandproduceapositivedisruptionofthebaseline.However,thiseffectcanbeminimizedbyheatingthecolumnto120ECfor1hourafteraday'sanalysis.3.2Glasswarecontainingtracesofchromiumshouldnotbeusedbecausechromiumwillformacomplexwithacetonitrile,therebyreducingt
8、heamountofacetonitrileavailableforquantitation.3.3Reagents,glassware,andoth
