高效氯氟氰菊酯、噻虫嗪及其代谢物噻虫胺在小麦中的残留及消解动态分析

Residue and Degradation Dynamic of Lambda-Cyhalothrin,Thiamethoxam and Clothianidin in Wheat

为了评价高效氯氟氰菊酯、噻虫嗪及其代谢物噻虫胺在小麦生产上的安全性,建立了气相色谱测定的高效氯氟氰菊酯及UPLC-MS/MS测定噻虫嗪和噻虫胺的残留分析方法,并对高效氯氟氰菊酯和噻虫嗪在小麦籽粒、植株和土壤中的消解动态进行了研究。结果表明,高效氯氟氰菊酯、噻虫嗪和噻虫胺在不同样品中的平均加标回收率为77.0%~105.6%,相对标准偏差为0.6%~11.1%;高效氯氟氰菊酯、噻虫嗪和噻虫胺在小麦籽粒、植株和土壤中的最低检测浓度均为0.05mg·kg-1,最小检出量分别为0.002 5、0.000 1、0.012ng。高效氯氟氰菊酯在小麦植株和土壤中的半衰期分别为8.0~12.4d和16.5~19.3d;噻虫嗪在小麦植株和土壤中的半衰期分别为1.2~2.5d和3.7~5.3d;2014年和2015年,在哈尔滨、新乡和银川市三地以240g·hm-2和360g·hm-2施药量分别施药2~3次,距最后一次施药14d时,高效氯氟氰菊酯、噻虫嗪和噻虫胺在小麦籽粒中的最高残留量均小于0.05mg·kg-1,低于我国国家标准(GB2763-2016)。

To assess the safety of lambda-cyhalothrin,thiamethoxam and clothianidin in wheat and soil,the method for determination of lambda-cyhalothrin by GC-ECD,thiamethoxam and clothianidin by UPLC-MS/MS in wheat filed environment has been established.Meanwhile,the characteristics of lambda-cyhalothrin,thiamethoxam and clothianidin degradation and residue were investigated by field experiments in Harbin,Xinxiang,and Yinchuan.The results showed that the average recovery rate of lambda-cyhalothrin,thiamethoxam and clothianidin in wheat,wheat plant and soil was in the range of77.0%^-105.6%,with their relative standard deviations of 0.6%^-11.1%.The minimum detectable concentrations of lambda-cyhalothrin,thiamethoxam and clothianidin in wheat,wheat plant and soil were all 0.05 mg·kg^-1,and the minimum detectable limit of lambda-cyhalothrin,thiamethoxam and clothianidin was 0.002 5 ng,0.000 1 ng,and 0.012 ng respectively.The field experiments revealed that the degradation half-lives of lambda-cyhalothrin were estimated from 8.0 dto 12.4 din wheat plant,and from 16.5 dto 19.3 din soil;the degradation half-lives of thiamethoxam were estimatedfrom 1.2 dto 2.5 din wheat plant,and from 3.7 dto 5.3 din soil.When the recommended dosage and 1.5 times recommended dosages of 15% lambda-cyhalothrin and thiamethoxam ZC was sprayed for 2 to 3 times at an interval of 14 days,the maximum residual concentration of lambda-cyhalothrin,thiamethoxam and clothianidin on the 14 th day after the last application were less than 0.05 mg·kg^-1.These values are below the maximum residue limits in wheat by the standards of China.