Study On The Analysis Method Of Aryloxyphenoxypropionic Acid And Sulfonylurea Herbicide Residues On Tobacco

The effect mechanism of aryloxyphenoxypropionate（APP）herbicides is to inhibit the synthesis of fatty acids and inhibit the growth of weeds by inhibiting the acetyl-coenzyme A carboxylase（ACCase）of grass weeds.The effect mechanism of sulfonylureas herbicides is to inhibit the synthesis of acetyl-lactate synthase（ALS）,prevent the biosynthesis of branched amino acids,and thus prevent the cell division and growth,so as to achieve the purpose of weeding,which were mainly used for the control of broadleaf weeds and grass weeds.This paper established a method for the residue analysis of APP and sulfonylurea herbicides in soil,fresh tobacco leaf,and flue-cured tobacco leaf,which was used to analyze the dissipation dynamics and final residues of haloxyfop-P-methyl and rimsulfuron in soil and tobacco leaf samples under field condition.The research results are as follows:1.In this paper,an optimized QuEChERS-the liquid chromatography tandem mass spectrometry（LC-MS/MS）method for simultaneous detect and analyz of 6 kinds of APP herbicides and 19 kinds of sulfonylurea herbicides in soil and tobacco was established by optimizing the conditions of liquid chromatography,mass spectrometry,and the pretreatment conditions.Validation results indicated that the established method had satisfactory linearity and sensitivity,with the correlation coefficient（R²ï¼‰>0.9904;the limits of detection（LOD）and limits of quantification（LOQ）of 25 herbicides in soil,fresh tobacco leaf,and flue-cured tobacco leaf were between 0.024–0.300 and 0.08–1.00 mg/kg,respectively.The average recoveries of 25 herbicides in soil,fresh tobacco leaf,and flue-cured tobacco leaf were between 72.61%and 114.40%,with relative standard deviation（RSD）between 0.44%and 11.55%.2.The dissipation dynamics of haloxyfop-P-methyl and rimsulfuron in soil from Guizhou and the dissipation dynamics of haloxyfop-P-methyl in soil from Hunan could not be fitted by first-order kinetic equation.The first-order kinetic equation of rimsulfuron in soil from Hunan in 2017 was C=0.2296e^-0.181t（R²=0.9389）,with half-lives of 3.83 d.The results showed that the initial residue concentrations of haloxyfop-P-methyl and rimsulfuron in Guizhou and Hunan soils was very low.3.The first-order kinetic equation of haloxyfop-P-methyl in fresh tobacco leaf from Guizhou in 2017 was C=0.76e^-0.193t（R²=0.6204）,with half-lives of 3.59 d.The dissipation dynamics of haloxyfop-P-methyl in fresh tobacco leaf from Hunan in 2017and the dissipation dynamics of rimsulfuron in fresh tobacco leaf from Guizhou and Hunan in 2017 could not be fitted by the first-order kinetic equation.4.Terminal residues of haloxyfop-P-methyl and rimsulfuron in soil from Guizhou and Hunan in 2017 was 0.24 mg/kg and<0.10 mg/kg,respectively.Terminal residues of haloxyfop-P-methyl and rimsulfuron in flue-cured tobacco leaf in 2017and 2018 was0.60 mg/kg and<0.25 mg/kg,respectively.