AOAC 991.04 AOAC Official Method 991.04 DDT

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1、AOACOfficialMethod991.04DDTinTechnicalProductsandFormulationsGasChromatographicMethodFirstAction1991CIPAC-AOACMethod(ApplicabletoDDTtechnicalanditswater-dispersiblepowder,emulsifiableconcentrate,anddustablepowderformulations.)Resultsoftheinterlaboratorystudysu

2、pportingtheacceptanceofthemethod:Technicalproduct:sr=0.84;sR=0.87;RSDr=1.12%;RSDR=1.16%Water-dispersiblepowder:sr=0.56;sR=0.81;RSDr=1.02%;RSDR=1.48%Emulsifiableconcentrate:sr=0.13;sR=0.40;RSDr=0.68%;RSDR=2.08%Dustablepowder:sr=0.07;sR=0.15;RSDr=0.82%;RSDR=1.80%A.Principl

3、eTestportionsaredissolvedinCHCl3with2,2-dinitrobiphenyladdedasinternalstandard.p,p-DDTcontentisdeterminedbygaschromatographywithflameionizationdetectionandquantitationbypeakareameasurements.B.SafetyAcuteoralLD50ofp,p-DDTforratsis113-118mg/kg[TheManual(1987),8t

4、hEd.,BritishCropProtectionCouncil,ThorntonHeath,UnitedKingdom].UseCHCl3onlywithadequateventilation.AvoidcontactofCHCl3witheyes,skin,orclothing.(SeealsosafetynoteonCHCl3.)C.ApparatusandReagents(a)Gaschromatograph.-Withflameionizationdetectorandsuitableforon-columninjectio

5、n.Operatingconditions:temperatures-injector250°C,detector275°C,column170°C;nitrogencarriergasflowca30mL/min.Retentiontimesforp,p-DDTandinternalstandardareca12.4and19.5min,respectively.Usepeakareameasurementsbyelectronicintegrationforquantitation.(b)GCcolumn.-Glass,2mmid1

6、.83m,packedwith5%OV-210(AlltechAssociates)on100-120meshChromosorbW(HP).(c)Internalstandardsolution.-Accuratelyweighca2.8g2,2-dinitrobiphenyl(97%pure,Aldrichorequivalent)into100mLvolumetricflask.DilutetovolumewithCHCl3,andmix.(d)p,p-DDTstandardsolution.-Accuratelyweighamo

7、untofp,p-DDTstandard(99%pure,Aldrichorequivalent)thatcontainsca200mgactiveingredientinto50mLscrew-capbottle.Addbypipet5.0mLinternalstandardsolutionand20.0mLCHCl3.Mixtodissolvep,p-DDT.D.PreparationofTestPortionAccuratelyweightestportionofDDTtechnicalorformulatedproducttha

8、tcontainsca200mgactiveingredient(p,p-DDT)into50mLErlenmeyerflaskwithPFTE-linedscrewcap.(Toestimateamoun