超高效液相色谱-串联质谱法分析氟虫双酰胺和噻嗪酮在茭白中的残留及消解动态

建立了超高效液相色谱-串联质谱 (UPLC-MS/MS) 检测氟虫双酰胺和噻嗪酮在茭白中残留的方法。样品采用乙腈提取，乙二胺-N-丙基硅烷 (PSA) 净化，0.1%甲酸-甲醇梯度洗脱，电喷雾正离子扫描，多反应监测模式，超高效液相色谱-串联质谱测定，外标法定量。结果表明:在0.005~1 mg/kg添加水平下，氟虫双酰胺和噻嗪酮在茭白植株和茭白中的平均回收率在81%~107%之间，相对标准偏差在4.2%~11%之间。消解动态规律符合一级动力学方程，氟虫双酰胺和噻嗪酮的半衰期分别为2.3 d和2.8 d，属易降解农药。最终残留试验结果表明:10% 阿维·氟酰胺悬浮剂按制剂用量450~675 g/hm2分别施药2和3次，间隔期5 d，距最后一次施药后7、14和21 d采样，氟虫双酰胺在茭白中的残留量均<0.01 mg/kg；25% 噻嗪酮可湿性粉剂按制剂用量600~900 g/hm2分别施药2和3次，间隔期5 d，距最后一次施药后7、14和21 d采样，噻嗪酮在茭白中的残留量为<0.005~0.078 mg/kg。建议10%阿维·氟酰胺悬浮剂最高制剂用量为450 g/hm2，最多施药2次，安全间隔期以7 d为宜；25%噻嗪酮可湿性粉剂最高制剂用量为675 g /hm2，最多施药2次，安全间隔期以21 d为宜。

Residue and dissipation dynamics of flubendiamid and buprofezin in Zizania latifolia by ultra performance liquid chromatography-tandem mass spectrometry

A new method had been developed to determine flubendiamid and buprofezin residues in Zizania latifolia. Samples were extracted by acetonitrile, nitrogen blowing to near dry, dissolve with methanol and clean up with PSA, gradient elution with 0.1% formic acid and methanol, then positive ions electrospray scanning with multiple reaction monitoring mode, detection with ultra high performance liquid chromatography tandem mass spectrometry, external standard method of quantitative. When the spike levels of flubendiamid and buprofezin ranged from 0.005 mg/kg to 1 mg/kg, the mean recoveries varied from 81% to 107% with the coefficient of variation of 4.2%–11%, respectively. The dissipation dynamics of flubendiamid and buprofezin conformed to first order kinetics equation with the half-lives was 2.3 d and 2.8 d, respectively. Given that the half-lives was short, flubendiamid and buprofezin could be classcified as the easily degradable pesticide type. In the final residue trials, at the 7^th, 14^th and 21^th days after the last spraying, the final residues of 10% avermectin·flubendiamid SC and 25% buprofezin WP were determined after two and three applications at levels of 450–675 g/hm² and 600–900 g/hm². The results revealed that residues of flubendiamid was lower than 0.01 mg/kg and that of buprofezin varied from lower than 0.005 mg/kg to 0.078 mg/kg. In conclusion, when 10% avermectin·flubendiamid SC were sprayed on Zizania latifolia twice according to the recommended dose of 450 g/hm², the safety interval of buprofezin in Zizania latifolia could be set as 7 d.When 25% buprofezin WP were sprayed in Zizania latifolia twice according to the recommended dose of 675 g/hm², the safety interval of buprofezin in Zizania latifolia could be set as 21 d.