溴氰菊酯和吡虫啉在甘蓝中的残留及消解行为研究

研究了溴氰菊酯和吡虫啉在甘蓝中残留的仪器检测方法,并在天津、山东和江苏连续开展了2 a溴氰菊酯和吡虫啉在甘蓝中残留状况和消解动态规律研究的田间试验。结果表明,在溴氰菊酯和吡虫啉的添加质量比分别为0.025~0.5 mg/kg和0.025~1 mg/kg的水平下,甘蓝中溴氰菊酯的平均添加回收率为92.19%~102.48%,变异系数为2.98%~9.46%;吡虫啉平均添加回收率为94.58%~100.30%,变异系数为0.85%~4.10%。甘蓝中溴氰菊酯和吡虫啉的最小检出量分别为0.1 ng和0.5 ng,甘蓝中溴氰菊酯和吡虫啉的最低检出质量比均为0.025 mg/kg。田间试验表明,在甘蓝莲座期施用20%溴氰菊酯.吡虫啉悬浮剂1次,溴氰菊酯和吡虫啉在甘蓝中的消解动态符合一级动力学反应模型,溴氰菊酯和吡虫啉在甘蓝中的残留消解半衰期分别为4.4~8.8 d和5.9~8.6 d。按照推荐剂量和1.5倍推荐剂量在甘蓝中施用20%溴氰菊酯.吡虫啉悬浮剂3~4次,2次施药间隔7 d,距最后一次施药10 d时,溴氰菊酯在甘蓝中的最高残留量低于GB2763—2005《食品中农药最大残留限量》规定的溴氰菊酯在甘蓝中的最大残留限量(0.5 mg/kg),以及NY 1500.5.6—2007《农产品中农药最大残留限量》规定的吡虫啉在甘蓝中的最大残留限量(1 mg/kg)。

Dissipation dynamics of deltamethrin and imidacloprid in cabbage

Gas chromatography(GC) and high-pressure liquid chromatography(HPLC) for determining deltamethrin and imidacloprid,respectively,was established in wild cabbage,and the residue and dissipation dynamics of deltamethrin and imidacloprid were investigated through two consecutive years’ field experiments in Tianjin,Shandong and Jiangsu.The results showed that the recovery rate of deltamethrin in wild cabbage was in a range of 92.19%-102.48%,with relative standard deviations(RSD) of 2.98%-9.46% at deltamethrin levels of 0.025-0.5 mg/kg.The average recovery rate of imidacloprid in wild cabbage was 94.58%-100.30%,with RSD of 0.85%-4.10% at imidacloprid concentrations of 0.025-1 mg/kg,The minimum detectable concentrations of imidacloprid and deltamethrin in wild cabbage were 1.0×10-10 g and 5.0×10-10 g respectively,whereas the minimum detectable rates of imidacloprid and deltamethrin were 0.025 mg/kg.The field experiments indicated that the residual dissipation dynamics of deltamethrin and imidacloprid in wild cabbage conformed to the first order kinetics reaction model when deltamethrin & imidacloprid suspension concentrates was sprayed for once.The residual half-life of deltamethrin and imidacloprid of deltamethrin and imidacloprid was 4.4-8.8 d and 5.9-8.6 d,respectively.When the recommended dosage and 1.5 times recommended dosages of 20% deltamethrin & imidacloprid SC were sprayed for 3-4 times at an interval of 7 d,the residue of deltamethrin and imidacloprid in wild cabbage met with the maximum residues level of pesticide in food for deltamethrin(0.5 mg/kg,GB 2763—2005) and for imidacloprid(1.0 mg/kg,NY 1500.5.6—2007).