基于QuEChERS-GC/MS法对土壤和甜菜中精异丙甲草胺的残留降解动态测定

【目的】研究精异丙甲草胺在甜菜及种植土壤中的残留降解动态。【方法】采用QuEChERS-GC/MS法，分析不同深度土壤和甜菜中施用的不同浓度的精异丙甲草胺。【结果】精异丙甲草胺在0.01～1.0 mg/L浓度范围内呈良好线性，相关系数为0.999 4,所建立的最小检出限为0.001 mg/kg;平均回收率在84.81%～110.45%,相对标准偏差(RSD,n=3)在1.36%～9.0%。1 296、1 944、3 888 g.a.i/hm²的精异丙甲草胺在0～5、5～10、10～15 cm的土壤以及甜菜中的降解遵循一级动力学方程，不同深度土壤中的残留量随浓度的增加而增加，随时间的延长而降低，不同施用浓度在不同深度土壤中的半衰期为9.12～17.77 d。施用浓度越高，降解速度越慢。在甜菜中的残留量和降解速率都低于土壤，半衰期较土壤中略高，3个浓度在甜菜中的半衰期分别为19.25、26.65和32.85 d。【结论】施用1 296和1 944 g.a.i/hm²的精异丙甲草胺，收获期在土壤和甜菜中的降解率均能达到90%;施用超剂量3 888 ...

Determination of Residual Degradation of S-Metolachor Residue in Soil and Sugar Beet by QuEChERS-GC/MS

【Objective】 This project aims to clarify the residual degradation dynamics of metolachlor in sugar beet and planting soil.【Method】 QuEChERS-GC/MS method was used to study the effects of different concentrations of S-Metolachor in different soil depths and sugarbeet.【Results】 The results showed that the S-Metolachorresidue was linear in the concentration range of 0.01-1.0 mg/L with a correlation coefficient of 0.999 4.The minimum detection limit was 0.001 mg/kg; the average recovery was 84.81-110.45%, relative standard deviation (RSD, n=3) was between 1.36% and 9.0%.The degradation of S-Metolachorresidue in 0-5, 5-10, 10-15 cm soil and sugar beet in 1,296, 1,944, 3,888 g.a.i/hm², following the first-order kinetic equation.The residue in different depth soil increased with the increase of concentration, and decreased with the extension of time.The half-life of different application concentration in different depth soil was 9.12-17.77 d.The higher the application concentration, the slower the degradation rate.The residual amount and degradation rate in sugar beet were lower than that in soil, and the half-life was slightly higher than that in soil.The half-lives of three concentrations in sugar beet were 19.25 d, 26.65 d and 32.85 d, respectively.【Conclusion】 The degradation rate of S-Metolachlor in soil and sugar beet can reach 90% when 1,296 g.a.i/hm² and 1,944 g.a.i/hm² are applied, and is lower than 80% when the dosage of S-Metolachlor is 3,888 g.a.i/hm².From the perspective of degradation rate, S-Metolachlor is easy to degrade in soil and sugar beet, which belongs a kind of degradable pesticide.