噻虫嗪及其代谢产物在盆栽辣椒和土壤中的残留动态和膳食风险评估

Residue Dynamics and Dietary Risk Assessment of Thiamethoxam and Its Metabolites in Potted Peppers and Soil

[目的]评价噻虫嗪在盆栽辣椒上使用的安全性,研究噻虫嗪及其代谢产物噻虫胺在盆栽辣椒和土壤中的残留降解动态和最终残留量。[方法]在温室种植条件下,按噻虫嗪药剂的推荐剂量0.13 g/L和1.5倍推荐剂量0.2 g/L在辣椒半成熟期时,以灌根方式施药1次,不同时间处理后,取土壤样品和辣椒样品进行检测分析。样品采用乙腈溶液提取,Qu ECh ERS方法净化,超高效液相-串联质谱法(UPLC-MS/MS)测定残留量,利用风险商值法对其进行膳食风险评估。[结果]在0.01~0.1 mg/kg添加水平下,噻虫嗪在辣椒和土壤中的平均回收率为80.1%~113.8%,相对标准偏差为0.14%~6.65%;噻虫胺在辣椒和土壤中的平均回收率为77.4%~105.5%,相对标准偏差为1.41%~7.46%。噻虫嗪在辣椒和土壤中半衰期分别为6.3、11.9 d。按低剂量和高剂量施药后14 d,辣椒中噻虫嗪的最终残留量分别为0.47、2.78 mg/kg,噻虫嗪在辣椒中残留的风险商值(RQ)为0.12。[结论]参照欧盟规定的噻虫嗪在辣椒中的MRL值(0.7 mg/kg)和中国规定的噻虫嗪在黄瓜中的MRL值(0.5 mg/kg),噻虫嗪按推荐剂量,以灌根方式施药1次,14 d后收获的辣椒食用是安全的,人类膳食风险较小。

[Aims] In order to evaluate the safety of thiamethoxam in potted peppers, trials were carried out to study the degradation dynamics and final residues of thiamethoxam and its metabolites in potted peppers and soil. [Methods]Under greenhouse cultivation conditions, the pepper plants were rootted at the recommended dosage（0.13 g/L） and 1.5 times of recommended dosage（0.2 g/L） for once when the peppers were half-mature. Soil and pepper samples were taken for testing and analysis after treatment at different times. The target compounds were extracted with acetonitrile, purified by QuEChERS method and detected by UPLC-MS/MS method. The dietary risk assessment was conducted using risk quotient method. [Results] At 0.01-0.1 mg/kg, the average recoveries of thiamethoxam in peppers and soil ranged from80.1 to 113.8%, the relative standard deviation（RSD） was 0.14-6.65%, the average recoveries of clothianidin in peppers and soil ranged from 77.4 to 105.5%, and RSD was 1.41-7.46%. The half-lives of thiamethoxam in peppers and soil were6.3 d and 11.9 d, respectively. When the doses were 0.13 and 0.2 g/L, the final residues of thiamethoxam in the peppers were 0.47 and 2.78 mg/kg, respectively, and the residual risk quotient（RQ） was 0.12. [Conclusions]Compared with the recommendedMRLs for thiamethoxamin pepper（0.7 mg/kg establised by EU） or in cucumber（0.5 mg/kg establised by China）, the dietary risk is relatively low in pepper with the recommended dosage after 14 d of pre-harvest interval.