乙基多杀菌素在稻田水、土壤和水稻植株中的残留及消解动态

Residue and decline dynamics of spinetoram in paddy water,soil and rice straw

采用超高效液相色谱-串联质谱（UPLC-MS／MS）方法，研究了乙基多杀菌素中2种主要组分（XDE-175-J和XDE-175-L）在稻田水、土壤和水稻植株中的残留分析及消解动态。土壤和植株样品采用乙腈提取，乙二胺-N-丙基硅烷（PSA）净化；田水样品用0．1％甲酸溶液和乙腈稀释；UPLC-MS／MS分析。结果表明：XDE-175-J和XDE-175-L在田水、土壤和植株中的检出限（LOD）分别为2．5×10-4mg／L和5．0×10-4、0．001mg／kg，定量限（LOQ）分别为0．001mg／L和0．002、0．005mg／kg。当添加水平为0．001～0．5mg／kg（L）时，乙基多杀菌素在田水、土壤和水稻植株中的平均回收率为83％～102％，相对标准偏差（RSD）为1．9％-6．2％。消解动态试验结果表明：6％乙基多杀菌素悬浮剂（SC）按1．5倍推荐使用高剂量（有效成分40．5g／hm2）于水稻拔节期施药1次，乙基多杀菌素在田水、土壤及水稻植株中的消解动态规律均符合一级动力学方程，半衰期分别为0．35、6．8和1．1d；施药21d后，其在水稻植株和田水中的消解率均在95％以上，在土壤中的消解率为86．1％；属易消解型农药。

The residual dynamics of two main components （XDE-175-J and XDE-175-L） of spinetoram in paddy water, soil and rice straw were measured by ultra performance liquid chromatography tandem mass spectrometry （UPLC-MS/MS）. The soil and rice straw samples were extracted with acetonitrile, cleaned up with PSA sorbent and analyzed by UPLC-MS/MS. The water samples were diluted with 0. 1% formic acid solution-acetonitrile and analyzed by UPLC-MS/MS. The limits of detection （LODs） of XDE-175-L and XDE-175-J in paddy water, soil and rice straw were 2.5 × 10 -4 mg/L, 5.0 ×10 -4 mg/kg and 0. 001 mg./kg, respectively. The limits of quantification（LOQs） in paddy water, soil and rice straw were 0. 001 mg/L, 0. 002 mg/kg and 0. 005 mg/kg, respectively. When the fortification level of XDE-175-L and XDE-175-J ranged from 0. 001 to 0. 5 mg/kg（ L）, the average recoveries of two compounds varied from 83% to 102% with the relative standard deviation of 1.9% to 6. 2%. The rice was sprayed with 6% spinetoram suspension concentrate（SC） at dosage a. i. 40.5 g/hm2 （ one time） at shooting stage of rice, the half-lives of spinetoram residue were 0. 35 d, 6. 8 d and 1.1 d in paddy water, soil and rice straw, respectively. The dissipation rate was over 95.0% in paddy water and rice straw and over 86. 1% in soil at 21 d after application. In conlusion, spinetoram belongs to the easily degradable pesticide type.