噻唑膦在黄瓜和土壤中的残留及消解动态研究

The Research on Residues and Decline of Fosthiazate in Cucumber and Soil

采用气相色谱-火焰光度检测器(GC-FPD)测定了噻唑膦在黄瓜和土壤样品中的消解动态及最终残留。黄瓜和土壤样品用乙腈提取、乙酸乙酯定容、GC-FPD检测。当噻唑膦在黄瓜和土壤中的添加浓度为0. 01～0. 5mg/kg时,回收率为82. 0%～107. 8%之间,相对标准偏差(RSD)为5. 6%～12. 3%;噻唑膦的最小检出量为1. 0×10-14g,黄瓜和土壤中的最低检测浓度为0. 01mg/kg。消解动态试验结果显示,噻唑膦在黄瓜和土壤的消解动态规律均符合一级动力学方程,其半衰期分别为2. 17～3. 81 d和5. 37～9. 76 d;最终残留试验结果表明,黄瓜中噻唑膦残留量最大值为0. 066mg/kg,低于我国规定的残留限量值0. 2mg/kg,建议在黄瓜地使用5%噻唑膦可溶液剂时,施药剂量为1 500 g. a. i/ha,施药1次,收获期黄瓜安全。

The decline and final residues of fosthiazate in cucumber and soil samples in supervised field trials were determined by gas chromatography equipped with flame photometric detector(GCFPD). Cucumber and soil samples were extracted with acetonitrile,metered volume by ethyl acetate and determined by GC-FPD. Under the fortified level from 0. 01 to 0. 5mg/kg for cucumber and soil,the recovery ranged from 82. 0% to 107. 8% with the relative standard deviations of 5. 6% ~12. 3%. The mimimum detectable amount was 1. 0 × 10^-14 g, and the limit of quantification(LOQ) of the method was 0. 01mg/kg for cucumber and soil samples. The decline test results showed that the rules consistent with first order kinetics equation,and the half-life of fosthiazate was 2. 17 ~ 3. 81 days in cucumber and 5. 37 ~ 9. 76 days in soil,respectively. The final residues results indicated that terminal residues in cucumber were less 0. 066mg/kg,below the MRL of China(0. 2mg/kg). Recommended dosage of 1 500 g. a. i/ha for 5% fosthiazate SL was suggested to apply in cucumber field with one time which is safe for cucumber.