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

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、0.001 mg/kg,定量限(LOQ)分别为0.001 mg/L和0.002、0.005 mg/kg。当添加水平为0.001~0.5 mg/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40.5 g/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1.1 d;施药21 d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。

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

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.