辛硫磷在宁夏甘草及对应根际土壤中的残留及消解动态

Residues and Degradation Dynamics of Phoxim in Glycyrrhiza uralensis and Rhizospheric Soil in Ningxia

为制定辛硫磷在甘草上的安全使用技术标准,采用田间试验和液相色谱法,测定辛硫磷在宁夏甘草及对应根际土壤中的残留及消解动态。样品经乙腈提取、柱层析法净化、紫外检测器检测,结果表明,在设定的色谱条件下,样品的最小检出量为1.00×10^-9g,最小检出含量为0.005 mg/kg。不同进样量测定结果表明,在0.1-10μg/mL的范围内,辛硫磷峰面积与进样量之间有良好的线性关系,线性方程为Y=1.2190X＋0.1658（r2=0.9940）。甘草中辛硫磷的添加回收率在81.7%-85.1%之间,RSD介于3.39%-5.91%之间,甘草对应根际土壤中辛硫磷的添加回收率在90.9%-95.3%之间,RSD介于2.89%~4.07%之间,各项指标均符合农药残留分析检测限量的要求。残留检测结果表明,药后不同时期甘草根及土壤中辛硫磷的残留含量完全符合一级反应动力学方程式,分别为CT=1.0024e-0.1027T（r=0.9715）和CT=0.4577e-0.0402T（r=0.9836）,残留消解较快,半衰期分别为6.75 d和17.24 d;40%辛硫磷乳油依推荐剂量1次施药后40 d,2次施药后53 d,在甘草及其土壤中的残留均低于0.05 mg/kg,因此建议40%辛硫磷乳油在甘草上依推荐剂量1次施药的安全间隔期不得少于40 d,2次施药的安全间隔期不得少于53 d。

In order to set up the safe using standard of Phoxim in Glycyrrhiza uralensis during mode planting of Glycyrrhiza uralensis,the paper used the methods of field experiment and liquid chromatography,determined the residues and degradation dynamics of Phoxim in Glycyrrhiza uralensis and rhizospheric soil.The samples was extracted with acetonitrile,purified with column chromatography and determined with ultraviolet determitor.The results showed that the minimum detemined quantity of samples was 1.00×10^-9 g and the minimum determined concentration was 0.005 mg/kg with the chromatography condition the paper made.The results of different sample size showed that there were good linear relation between peak area and sample size of Phoxim in the range from 0.1 μg/mL to 10 μg/mL and the equation was Y=1.2190X＋0.1658（r2=0.9940）.The fortified recoveries of Phoxim in Glycyrrhiza uralensis was between 81.7% and 85.1%,RSD was between 3.39% and 5.91%.The fortified recoveries of Phoxim in soil was between 90.9% and 95.3%,and RSD was between 2.89% and 4.07%,which all conformed to the analyzing remands of pesticides residues.The results of residues indicated that the residues of Phoxim in Glycyrrhiza uralensis and soil conformed completely to the equation of first-class reaction kinetics,they were CT=1.0024e-0.1027T（r = 0.9715） and CT=0.4577e-0.0402T（r = 0.9836）,respectively.The residues degradated much more quickly,the half-lives were 6.75 d and 17.24 d,respectively.The residues of Phoxim 40%（EC） in Glycyrrhiza uralensis was less than 0.05 mg/kg with recommended dosage one time in 40 d,and the residues in Glycyrrhiza uralensis and soil were all less than 0.05 mg/kg after two times spray 53 d.Therefore,we suggested that the safe interval of Phoxim 40%（EC） in Glycyrrhiza uralensis with recommended dosage one time spray should be more than 40 d and that should be more than 53 d with two times spray.