Residue Analysis And Digestion Dynamics Study Of 3.2% Avermectin EC On Artemisia Selengensis And Soil

In this study,an analytical method for the determination of the residue of abamectin in soil and chrysanthemum cornarium L.by ultra-performance liquid chromatography(UPLC-PDA)and liquid chromatography coupled with tandem mass spectrometry(LC-MS/MS)was established.The data of the final residues were summarized,which provided data reference for the setting of the maximum residue limits of abamectin in chrysanthemum cornarium L..The soil samples were vibrated with acetone.Afterwards the solution were suction filtrated though Hirsch funnel and washed the residue with acetone.All of the solution were combined and evaporated to remove acetone completely,then purified with dispersive solid-phase extraction.Finally,the residue of abamectin in soil was determined by UPLC-PDA.The chrysanthemum cornarium sample was extracted with acetonitrile,then sodium chloride and anhydrous magnesium sulfate were added before centrifugation.One half of solutions were concentrated,followed by purifying with dispersive solid-phase extraction.Finally,the residue of abamectin in chrysanthemum cornarium was determined by LC-MS/MS.The results showed that the pure solvent calibration curve determined by UPLC-PDA has a good linear in the range of 0.2~50 μg/mL and the correlation coefficient(R2)was 1.The limit of detection(LOD)and the limit of quantification(LOQ)of abamectin were 6×10-11 g and 0.01 mg/kg,respectively.The matrix-matched calibration curve determined by LC-MS/MS has a good linear in the range of 0.025~1.0 μg/mL and the correlation coefficient(R2)was 0.9939.The limit of detection(LOD)and the limit of quantification(LOQ)of abamectin were 5.0×10-14 g and 0.005 mg/kg,respectively.The average recovery of abamectin in soil and chrysanthemum cornarium was 80.47~96.12% and 73.13~97.72% and the relative standard deviations were less than 15% at the spiked level of 0.01~1 mg/kg and 0.005~0.2 mg/kg.The results showed that the precision,accuracy and sensitivity of this method could determine the residue of abamectin in soil and chrysanthemum cornarium.The field trials of 3.2% abamectin(EC)were carried out in Guizhou,Anhui,Beijing,Guangxi,Henan,Heilongjianeg in chrysanthemum cornarium and soil in 2016.The residue of abamectin in chrysanthemum cornarium was also studied.After the last application for the dosage of 11.2 g a.i/ha were performed two times,that the residues of abamectin in chrysanthemum cornarium were lower than 0.05 mg/kg at 5 days,a level equal to the MRL in spinach(GB 2763-2004).In addition,the degradation of abamectin in soil was carried out in the laboratory simulation.The degradation behavior of abamectin in three different soils,namely,Guizhou yellow soil,Anhui sandy soil and Beijing sandy loam soil were discussed,which made an explanation to the degradation of abamectin without regularity for some uncontrollable factors.Furthermore,the degradation tendency in soil under sterilized condition was studied.