醚菌酯在黄瓜和土壤中的残留及消解动态研究

Residue and Dissipation Dynamics of Kresoxim-methyl in Cucumber and Soil

在安徽、广西和山东3地开展50%醚菌酯水分散粒剂在黄瓜及土壤中的田间残留及消解动态试验。建立了测定黄瓜和土壤中醚菌酯的气相色谱-电子捕获检测器(GC-ECD)分析方法。样品经乙腈振荡提取,离心分层进GC-ECD进行检测。结果表明,在0.005~5.000 mg/L浓度时,线性关系良好,r均大于0.9997。在4个添加水平下,醚菌酯的平均回收率在88%~109%,相对标准偏差(RSD)小于2.4%;在黄瓜和土壤中的定量限(LOQ)均为0.005 mg/kg。田间试验结果表明,醚菌酯在黄瓜和土壤中的消解符合一级动力学方程,在黄瓜中的半衰期为1.6~4.1 d,在土壤中的半衰期为2.4~6.2 d;距末次施药后3~10 d,醚菌酯在黄瓜中的最高残留量为0.081 mg/kg,低于我国规定的黄瓜中醚菌酯最大残留限量值(0.500 mg/kg)。

Field trials were conducted to evaluate the dissipation and residue of 50%kresoxim-methyl WG in cucumber and soil in Anhui Province,Guangxi Province and Shandong Province.A gas chromatography with electron capture detector(GC-ECD)method was developed for the determination of kresoxim-methyl in cucumber and soil samples.The samples were extracted with acetonitrile by oscillation,then centrifuged and filtered and detected by GC-ECD.The results showed that,the linearity of kresoxim-methyl was in the concentration range of 0.005-5.000 mg/L with correlation coefficients higher than 0.9997.The average recoveries of kresoxim-methyl in cucumber and soil were in the ranges of 88% to 109% at four spiked levels of 0.005,0.05,0.5 and 5.0 mg/kg,and the relative standard deviation(RSD)was less than 2.4%.The limit of quantification(LOQ)of kresoxim-methyl was 0.005 mg/kg which was the lowest spiked concentration.The results demonstrated that dissipation of kresoxim-methyl in cucumber and soil was in accordance with the first-order kinetic equation with the half-lives from 1.6 d to 4.1 d in cucumber and 2.4 d to 6.2 d in soil.The highest residue of kresoxim-emthyl in cucumber was 0.081 mg/kg,which was lower than the maximum residue limit(MRL,0.500 mg/kg)of kresoxim-methyl in cucumber in China,when measured 3-10 d after final application.It was safe for human being when using this fungicide to control powdery mildew on cucumber.