Residue Detection And Digestion Dynamics Of Lambda-cyhalothrin, Dinotefuran And Its Metabolites On Apples

Due to the high bioactivity and broad spectrum,lambda-cyhalothrin and dinotefuran have been widely used in agricultural production and pest control all over the world.1.A modified QuEChERS-gas chromatography(GC)method was developed to determine the residues of lambda-cyhalothrin in soil and apple.Moreover,the matrix effects in soil and apple were investigated and evaluated.The soil and apple samples were extracted with acetonitrile and purified by graphitized carbon black(GCB).The linearity of lambda-cyhalothrin was good in the range of 0.05-10 ?g/mL with correlation coefficients(R2)> 0.999.The limits of detection(LODs)and quantification(LOQs)were 0.12-0.15 ?g/kg and 0.38-0.50 ?g/kg,respectively.Based on the matrix-matched calibration,the recoveries were 88.29%-97.65% and 80.70%-98.69% in soil and apple,respectively,which were in the acceptable range.Matrix enhancement effects were observed in the soil and apple.The established method could be successfully applied on the residual analysis of lambda-cyhalothrin in actual soil and apple samples.The matrix-matched calibration solution could efficiently compensate the matrix effects of lambda-cyhalothrin in GC.2.Residues of dinotefuran and its metabolites,1-methyl-3-(tetrahydro-3-furylmethyl)urea(UF)and 1-methyl-3-(tetrahydro-3-furylmethyl)guanidine(DN),in soil and apple were investigated by modified QuEChERS pretreatment and liquid chromatography-tandem mass spectrometry.The LODs and LOQs of dinotefuran,UF and DN in apple were 0.011-0.960 and 0.037-3.200 ?g/kg,respectively.Average recoveries of dinotefuran,UF and DN in soil and apple ranged 70.0% to 83.6% with relative standard deviations less than 13%.A formulation of 20% dinotefuran water dispersible granules was sprayed at 1-1.5 fold recommended dose 3-4 times on apple trees.The terminal residues of dinotefuran in apple were less than 2 mg/kg(maximum residue limit(MRL)set by Japan).When following the recommended application information,the risk of dinotefuran could be negligible to Chinese because of risk quotient(RQ)< 100%.These data could provide guidance for the safe use of dinotefuran and serve as a reference for the establishment of MRL of dinotefuran in apple in China.