农田土壤中抗倒酯及其代谢物抗倒酸残留量检测方法的建立与应用

为了探明抗倒酯及其代谢物抗倒酸在农田土壤中的残留消解规律,采用高效液相色谱检测技术(HPLC–UV),通过添加回收试验法建立农田土壤中抗倒酯和抗倒酸残留量的检测方法。结果显示:用酸性乙腈振荡法提取农田土壤中残留的抗倒酯和抗倒酸,用氟罗里硅土分散固相萃取法净化提取液后进行HPLC–UV检测,当添加浓度为0.05、0.50、5.00 mg/kg时,抗倒酯的添加回收率为79.68%~103.55%,变异系数为1.26%~10.22%;抗倒酸的添加回收率为79.18%~104.13%,变异系数为3.29%~10.75%。结果表明该方法符合农药残留量分析与检测的技术要求。在此基础上,采用室内模拟试验研究20℃恒温和避光培养条件下抗倒酯和抗倒酸在2种湖南典型农田土壤(第四纪红土红壤和河潮土)中的残留消解情况,结果显示:抗倒酯和抗倒酸在2种供试农田土壤中的残留消解均符合一级化学反应动力学方程C_t=C_0·e~(–kt),抗倒酯在第四纪红土红壤和在河潮土中的消解半衰期分别为8.92、7.67 d,抗倒酸的消解半衰期分别为9.39、8.59 d,表明抗倒酯和抗倒酸在2种供试农田土壤中的消解均较快,不易形成残留危害。

Development and application of the residual determination on trinexapac-ethyl and its degradation product trinexapac in farmland soil

The determination approach for trinexapac-ethyl, and its degradation product, trinexapac was set up through the additive recovery experiment with HPLC-UV technology to understand their residual level and degradation rule in farmland soil. The residues of trinexapac-ethyl and trinexapac in farmland soil were firstly extracted using acidic acetonitrile, and the extract was purified with florisil dispersive solid phase extraction, then we employed HPLC-UV to detect their residue. The results showed that when the additive concentration of trinexapac-ethyl varied from 0.05 to 5.00 mg/kg, the additive recoveries changed from 79.68% to 103.55%, with the coefficient of variation varied from 1.26% to 10.22%; while, the trinexapac,s recoveries varied from 79.18% to 104.13%, and its variation coefficient varied from 3.29% to 10.75%. The approach met the technical needs for pesticide residue analysis and determination. A case study of the residue and degradation on trinexapac-ethyl and trinexapac in two kinds of typical farmland soil, i.e., quaternary red soil and alluvial soil from Hunan were conducted under indoor simulation culture experiment at 20℃ and dark condition, the results showed that their residue and degradation accorded with the first-order kinetic equation which was written asCt=C0·e-kt, and the degradation half-life of trinexapac-ethyl was 8.92 days in quaternary red soil, and 7.67 days in alluvial soil; while those of trinexapac was 9.39 days and 8.59 days, respectively. Both the degradation rate of trinexapac-ethyl and trinexapac were faster in the two kinds of typical farmland soil, and it was no risk to the farmland soil environment.