乙嘧酚在黄瓜和土壤中的消解动态研究

Degradation Dynamics of Ethirimol in Cucumber and Soil

利用高效液相色谱仪及田间试验方法,建立了乙嘧酚在黄瓜和土壤中的残留分析方法,研究了乙嘧酚在黄瓜和土壤中的残留消解动态,对影响残留分析方法的主要参数进行了优化。黄瓜和土壤样品分别用乙腈和丙酮提取,硅胶柱净化,高效液相色谱仪二极管阵列检测器检测,外标法定量。结果表明,该方法的最小检出量为3.5×10-10 g,在黄瓜和土壤中的最低检测浓度分别为0.010和0.005 mg.kg-1。乙嘧酚的平均添加回收率为80.5%～103.1%,变异系数为2.10%～3.74%。消解动态试验表明,乙嘧酚的残留量随时间延长而降低,消解动态曲线符合一级动力学方程,在黄瓜和土壤中的半衰期分别为3.5和9.9 d,属于易降解性农药化合物。乙嘧酚在黄瓜中消解速率高于其在土壤中的消解速率,这可能是由于黄瓜生长稀释作用导致的。

A simple, reliable and accurate method has been developed to determine ethirimol residue in cucumber and soil, and the degrada- tion dynamics of ethirimol in cucumber and soil were studied. Parameters, affecting the performance of analysis such as absorption wavelength, mobile phase, amount of water added into soil and clean-up procedure, were studied and optimized. Under the optimum conditions of analysis （ Cucumber and soil samples were extracted by acetonitrile and acetone, respectively; then, the extracted solution was cleaned up by silica gel cartridge and analyzed by HPLC equipped with DAD; finally, the residual content was quantified by ESTD ）, the performance of the method was evaluated. The results showed the limit of detection of the method was 3.5× 10^-10 g, and the limit of quantificaiton in cucumber and soil were 0.010 mg· kg^-1 and 0.005 mg· kg^- 1, respectively. Average fortified recovery of the method varied from 80.5% to 103.1% with the relative standard deviation varying from 2.10% to 3.74%. Furthermore, the degradation dynamics indicated ethirimol degraded along prolongation of time, the curve of degradation dynamics accorded with the first-order kinetics equation, and the half-lives of ethirimol in cucumber and soil were 3.5 day and 9.9 day, respectively. The degradation rate of ethirimol in cucumber was faster than that in soil, which probably resulted from the dilution effect of cucumber＇ s growth. To sum up, ethirimol should be classified as easily degradable agrochemical and the gained parameters of degradation dynamics provided scientific basis for the safety evaluation on ethirimol.