丙炔噁草酮在水稻及稻田环境中的残留消解动态

为科学评价丙炔噁草酮在水稻田中安全性,采用田间试验方法,监测了丙炔噁草酮在水稻和稻田环境中的残留消解动态及最终残留量。稻壳样品采用二氯甲烷提取,稻田水、土壤、植株和糙米样品用乙腈振荡提取,经玻璃层析柱净化,气相电子捕获检测器分析测定。结果表明:稻田水、土壤、植株、稻壳和糙米中丙炔噁草酮添加浓度为0.01～1.0 mg/kg时,平均添加回收率为82.4%～99.6%,相对标准偏差为1.62%～7.56%,方法最低检测浓度均为0.01 mg/kg。丙炔噁草酮在田水、土壤和植株中的消解规律均符合一级动力学方程Ct=Coekt,消解半衰期分别为2.4～5.4、10.0～12.7、2.4～5.8天。以低剂量112.5 g a.i./hm2和高剂量168.75 g a.i./hm2施药丙炔噁草酮一次,收获期在土壤、植株、稻壳和糙米中的最终残留量均低于检出限。丙炔噁草酮在糙米中的残留量低于中国和欧盟规定的最大残留限量(MRL)标准。

Residues and Degradation Dynamics of Oxadiargyl in Rice and Environment

To evaluate the safety of oxadiargyl in paddy field, a field experiment was conducted to study the residues and degradation dynamics of oxadiargyl in rice and environment. The residues of rice shell samples were extracted with dichloromethane, and paddy water, soil, rice plant and brown rice samples were extracted with acetonitrile, the samples were cleaned up by glass chromatographic column and determined by GC-ECD. The results showed that when the concentration of oxadiargyl in paddy water, soil, rice plant, rice shell and brown rice samples ranged from 0.01 to 1.0 mg/kg, the average recovery was 82.4%-99.6%, with the variation coefficient of 1.62%-7.56%, the minimum detectable mass fraction (LOQs) was 0.01 mg/kg. Degradation of oxadiargyl in paddy water, soil and rice plant conformed to chemical kinetic equation C_t=C_oe^kt, with the half-life of 2.4-5.4, 10.0-12.7 and 2.4-5.8 days, respectively. Oxadiargyl was applied at the dosage of 112.5 and 168.75 g a.i./hm², each for once, the final residue of oxadiargyl in soil, rice plant, rice shell and brown rice were all below the detection limits. The results reveal that the residue of oxadiargyl in brown rice is less than the MRL set by China and EU.