环戊噁草酮在稻田中的残留及消解动态

建立了超高效液相色谱-串联质谱测定糙米、谷壳、稻秆、土壤和稻田水中环戊草酮残留的分析方法,结合田间试验研究了环戊草酮在稻田中的残留及消解动态。结果表明:在0.01～1 mg/L范围内,环戊草酮的质量浓度与相应的峰面积间呈良好的线性关系。在0.02、0.05和0.5 mg/kg添加水平下,环戊草酮在糙米、谷壳、稻秆、土壤和稻田水样品中的平均回收率在75%～95%之间,相对标准偏差在1.5%～9.5%之间,检出限 (LOD) 为0.01 ng,在糙米、谷壳、稻秆、土壤和稻田水中的最低检出浓度 (LOQ) 为0.02 mg/kg。浙江、山东和湖南3地2年的田间试验表明:环戊草酮在稻秆和土壤中的半衰期分别为4.2～9.0 d和7.0～11.6 d,其消解规律符合一级反应动力学方程。分别以有效成分含量375(低剂量) 和562.5 g/hm2(高剂量)2个剂量施用90 g/L环戊草酮悬浮剂1次,于收获成熟期采样检测发现,环戊草酮在糙米中的最终残留量均小于0.02 mg/kg,该研究结果可为制定环戊草酮在糙米中的最大残留限量值 (MRL) 提供数据支撑。

Residues and dissipation dynamics of pentoxazone in rice paddy

An analysis method using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was established for the determination of pentoxazone residues in the husked rice, rice hulls, rice plant, soil and paddy water. The residue and dissipation dynamics of pentoxazone in the rice paddy were investigated by field experiments. The calibration curve with good linearity was obtained in the concentration range of 0.01 to 1 mg/L. The average recoveries of pentoxazone in husked rice, rice hulls, rice plant, soil and paddy water were 75%-95% with relative standard deviations (RSDs) of 1.5%-9.5% at the spiked levels of 0.02, 0.05 and 0.5 mg/kg. The limit of detection (LOD) was 0.01 ng using this analytical method. The limits of quantitation (LOQ) of pentoxazone in those samples were all 0.02 mg/kg. The results of field experiments showed that the dissipation dynamics were fitted to the first-order kinetics equation, and the half-lives of pentoxazone in the rice plant and soil were 4.2-9.0 d and 7.0-11.6 d, respectively. When 90 g/L pentoxazone SC was sprayed once with the dose of 375 g a.i./hm² or 562.5 g a.i./hm², the final residues of pentoxazone in the husked rice were lower than 0.02 mg/kg at the harvest date. This study can be used as an important supportive data for the maximum residue limits (MRL) standard development of pentoxazone in the husked rice.