毒死蜱在梨和土壤中的残留研究

毒死蜱在梨果上的残留动态和最终残留试验,用带有火焰光度检测器的气相色谱测定其残留量。其最小检出量为0.1ng,在梨和土壤中的最低检测浓度均为0.05mg/kg。在梨和土壤中的平均回收率为85%～98%,变异系数为0.88%～3.23%,符合农药残留分析的要求。研究结果表明,毒死蜱在梨上的半衰期为5.2d,在土壤中的半衰期为5.6d。毒死蜱按推荐剂量250a.i.mg/L和推荐剂量的2倍500a.i.mg/L使用2、3次,末次施药距收获间隔7～28d,毒死蜱在梨中的残留量为0.05～0.347mg/kg,土壤中为0.05～0.102mg/kg,残留量低于我国规定的毒死蜱在梨中的MRL值1mg/kg,欧盟、日本规定毒死蜱在梨上的最高残留限量0.5mg/kg,美国规定毒死蜱在梨上的最高残留限量0.05mg/kg。建议毒死蜱在梨上按推荐施用剂量250a.i.mg/L,施药2～3次,安全间隔期为7d。

Study on the Chlorpyrifos Residues in Pear and Soil

The study on chlorpyrifos residues in pear and soil was carried out.The residues were determined using GC-FPD,the limit of detection of the GC method was 0.1ng,the limits of concentration detected were both of 0.05mg/kg for pear and soil.the average recoveries were 85%～98%,and the relative standard deviations were 1.7%～13.3%,which were met with the requirements of pesticide residue analysis.The results showed that the half-life of chlorpyrifos in pear and soil were 5.2 and 5.6 days respectively,the final residues of chlorpyrifos were 0.05～0.347mg/kg in pear,and 0.05～0.102mg/kg in soil,when sprayed with chlorpyrifos for 2 or 3 times at the dosages of 250mg/L and 500mg/L,and with intervals of 7～28 days before harvest,It did not exceed the Chinese MRL of 1 mg/kg and EU and Japanese MRLs of 0.5mg/kg on/in pear.So the use pattern of chlorpyrifos were recommended as 2～3 times application at a dosage of 250mg/L and with a PHI of 7 days.