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7.7.30(b)Acephate.—³99%(availablefromTomenAgro,Inc.,AOACOfficialMethod996.03100FirstSt,SanFrancisco,CA94105,USA).AcephateinTechnicalMaterial(c)Diisobutylphthalate.—³99%.andSolublePowderFormulations(d)Diisobutylphthalateinternalstandardsolution.—Accu-GasChromatographicMethodratelyweigh1.2g(±0.1g)diisobutylphthalate,(c),anddiluteto4LFirstAction1996withmethylenechloride,(a).Storeatroomtemperature.FinalAction2001(e)Acephatestandardsolution.—Accuratelyweigh100mgAOAC–CIPACMethod(±1.0mg)acephateofknownpurityinto100mLvolumetricflask.Dilutetovolumewithdiisobutylphthalateinternalstan-[Applicabletodeterminationofacephateintechnicalmaterialanddardsolution,(d).Stopperandshakeuntilcontentsaredis-solublepowderformulationscontaining>70%acephateastheonlysolved.Prepareacephatestandardsolutionjustbeforeactiveingredient.]analysis.SeeTable996.03forresultsoftheinterlaboratorystudysupport-D.PreparationofTestSolutioningtheacceptanceofthemethod.(a)Technicalacephate.—AccuratelyweighanamountoftestA.Principlesamplecontaining100±0.1mgacephate,into100mLvolumetricAcephateisdissolvedinmethylenechloridecontainingflask.Dilutetovolumewithdiisobutylphthalateinternalstandarddiisobutylphthalateasinternalstandard,separatedbygaschroma-solution,C(d).Stopperandshakeuntilcontentsaredissolved.tographywithflameionizationdetection,andquantitatedbypeak(b)Acephateformulatedproduct.—Removeinsolubleinertma-arearatios.terialfromacephateformulatedproductpriortoanalysisasfollows:(Note:InertmaterialmaycloginjectionsyringesusedbymanualorB.Apparatusautomaticsamplers.)Accuratelyweighanamountoftestsample(a)Gaschromatograph(GC).—Withflameionizationde-containing100±0.1mgofacephate,into100mLvolumetricflask.tector.Operatingconditions,temperatures,°C:column155;Dilutetovolumewithdiisobutylphthalateinternalstandardsolu-injector,170;flameionizationdetector,250;flowratesdependtion,C(d).Stopperandshake30stoensurecompletesolubilizationoninstrumentandmanufacturer’sspecifications(typicallyofacephateinmethylenechloride.Beforeanalysis,filteraliquotof[mL/min]:N,30–60;H,30–60;air,240–300).Suggestednom-testsolutionthroughsyringefilterasfollows:Usingsyringe,B(e),inalcolumnflowrate,30mL/min.Adjustflowrateorcolumntransferanaliquotoftestsolutionto20mLvial,attachsyringefilter,temperaturetomaintain2–4minretentiontimeforacephate.B(f),andexpelportionintoautosamplerorother20mLvial.[Note:Peaksforacephateandinternalstandard(diisobutylphthalate)Topreventlossofmethylenechloridefromtestsolution,closeflasksshouldbeseparatedatbaseline.orautosamplervialsimmediatelyafteraddingdiisobutylphthalate(b)GCcolumn.—500´2mmid,glasscolumn,packedwithinternalstandardsolution,C(d).]10%trifluoropropylmethylsiliconeon100–120meshinertdiat-omite(e.g.,SP-2401isacceptable).ConditionfreshlypackedE.GCDeterminationcolumns24hat250°CwithNflowat30mL/min.(Note:Itiscriti-calthatGCcolumnspecifiedisused.The10%stationaryphaseAdjustoperatingparametersofchromatograph,soacephateandloadingisimportantforobtainingoptimumperformanceofdiisobutylphthalateeluteascloseaspossible,butstillmaintainingmethod.)clearbaselineseparation.Ifbaselineseparationofacephateand(c)Glassvials.—20mL,withpolyethylenelinedscrewcaps.diisobutylphthalatecannotbeobtained,replaceGCcolumn.(d)Volumetricflasks.—100mL;classA.Makerepetitiveinjectionsofacephatestandardsolution,C(e),ontoGCcolumnuntilpeakarearatios(i.e.,diisobutylphthalate/acephate)(e)Syringes.—5mLwithLuersliptips;disposable.ofsequentialinjectionsarewithin2%.(f)Syringefilters.—25mm,0.45mmporosity;disposable.MakeduplicateinjectionsoftestsolutionfromD.ResponseratiosC.Reagentsoftestsolutioninjectionsshouldagreewithin2%.Otherwise,repeat(a)Methylenechloride.—³99.5%.analysisstartingwithinjectionofacephatestandardsolution.Table996.03InterlaboratorystudyresultsfordeterminationofacephateintechnicalmaterialandsolublepowderformulationsabyGCmethodbProducttypeConcentration,%Mean,%sRRRSDR,%Formulated7170.731.544.272.187372.320.982.721.367574.012.025.602.73Technical9595.992.055.682.139796.412.466.822.559999.781.032.851.03aStatisticalanalysisbasedonasingledeterminationfromeachof11collaboratinglaboratories.bR=2.8´s.R©2002AOACINTERNATIONAL
Re-injectacephatestandardsolution,C(e).ResponseratiosofPRave-testWstdPercentacephate=´´PacephatestandardsolutioninjectionsimmediatelybeforeandaftertestPRWave-stdtestsolutioninjectionsshouldagreewithin2%.Otherwise,repeatanalysissequencestartingwithinjectionofacephatestandardsolution.wherePRave-test=averageof2peakarearatiosofacephateintestsolu-(Note:Minimizelossofmethylenechloridefromtestsolutionbyre-tion;PRave-std=averageof2peakarearatiosofacephateinacephateplacingcaponvialimmediatelyafterremovingaliquot.)standardsolution(obtainedimmediatelybeforeandaftertestsolutionF.Calculationinjection);Wstd=weightofacephatestandard,mg;Wtest=weightoftestportion,mg;P=percentagepurityofacephatestandard.Calculatepeakarearatios(PR)asfollows:Reference:J.AOACInt.80,459(1997).PR=PI/PACAS-30560-19-1(acephate)AcetylphosphoramidothioicacidO,5-dimethylester;orthenewherePI=diisobutylphthalatepeakarea;PA=acephatepeakarea.Calculatepercentacephateintestsampleasfollows:Revised:March2002©2002AOACINTERNATIONAL
