噻呋酰胺在马铃薯和土壤中检测方法及残留动态研究

建立了马铃薯果实、植株和土壤样品中噻呋酰胺的分析方法,并测定了噻呋酰胺在马铃薯田中的残留消解动态及最终残留量。样品采用丙酮提取,二氯甲烷萃取,气相色谱-电子捕获检测器（GC-ECD）检测。当样品中添加的质量分数为0.001～0.05 mg·kg^-1时,平均添加回收率为85.76%～93.53%,相对标准偏差（RSD）为1.44%～7.33%,噻呋酰胺的最低检出质量浓度（LOQ）为0.001 mg·kg^-1。2009—2010年在天津和南京两地的田间残留试验结果表明：噻呋酰胺在马铃薯植株和土壤中消解较快,半衰期分别为6.08～6.30 d和4.92～7.07 d,施药后21 d的消解率均在91%以上;240 g·L^-1噻呋酰胺悬浮剂按推荐剂量480 g·hm^-2和1.5倍推荐剂量720 g·hm^-2兑水喷雾1次,在马铃薯收获期时噻呋酰胺在马铃薯果实和土壤中的最终残留量分别为质量浓度0.076 2～0.649 6 mg·kg^-1和0.020 7～0.305 0 mg·kg^-1。根据大田试验结果,建议噻呋酰胺在马铃薯中的最大残留限量标准为1.0 mg·kg^-1。

Residue Determination and Degradation of Thifluzamide in Potato and Soil

A method for determination of the thifluzamide residue in the potato,potato plant and soil was established. The field residue decline study and final residue trials of thifluzamide in potato in Tianjin City and Nanjing City were designed. Samples were extracted with acetone,partitioned by methylene chloride,and then detected by gas chromatography（GC）with electron capture detector（ECD）. The fortified recovery at level of 0.001 mg·kg^-1 to 0.05 mg·kg^-1 was ranged from 85.76% to 93.53%,with relative standard deviation of 1.44% to 7.33%. The limit of quantification was 0.001 mg·kg^-1. The half-life of thifluzamide in potato plant and soil were 6.08～6.30 d and 4.92～7.07 d respectively,with over 91% degradation rate after 21 d pesticide application. When the recommended dosage（480 g·hm^-2） and 1.5 times recommended dosages（720 g·hm^-2）of 240 g·L^-1 thifluzamide SC was sprayed once,the final residues of thifluzamide in potato and soil were between 0.076 2～0.649 6 mg·kg^-1and 0.020 7～0.305 0 mg·kg^-1,respectively at harvest time. According to the results of this study,the maximum residue limit of thifluzamide in the potato is 1.0 mg·kg^-1.