毒死蜱在棉花和土壤中的残留分析及消解动态研究

Residue analysis and dissipation dynamics of chlorpyrifos in cotton and soil

【目的】对毒死蜱在棉花和土壤中的安全性进行评价,为该农药在棉花上的合理使用提供科学依据。【方法】通过建立的毒死蜱在棉籽、棉花叶和土壤中的前处理方法和气相色谱—火焰光度检测器的仪器方法,对毒死蜱进行定量分析;通过两年（2009、2010年）两地（河南、江苏）的残留试验,研究毒死蜱在棉籽、棉花叶和土壤中的残留及消解动态。【结果】毒死蜱在棉籽、棉花叶及土壤空白添加平均回收率为73.50%~105.66%,相对标准偏差为3.25%~9.89%,其最小检出量为2.5×10-11g,在棉籽、棉花叶及土壤中的最低检测浓度分别为0.013、0.012和0.005 mg/kg。2009和2010年,在河南和江苏两地,毒死蜱在棉花叶和土壤中的消解半衰期分别为3.0~4.0、6.2~8.9 d;不同采样间隔及施药次数,毒死蜱在棉籽中的最终残留量均≤0.026 mg/kg。【结论】毒死蜱在棉籽中为低残留、易消解农药,可用于棉花斜纹夜蛾的防治,用药量以562.5 g a.i./ha为宜,施药3次,安全间隔期21 d。

【Objective】Safety assessment of chlorpyrifos in cotton and soil was conducted to provide important scientific references for the rational use of pesticides in cotton. 【Method 】The quantitative analysis of chlorpyrifos was done by GC-FPD and the established pretreatment method of chlorpyrifos in cottonseed, leaf of cotton and soil. Dissipation dynamics and residues of chlorpyrifos in cottonseed, leaf of cotton and soil were studied through residue experiments in two years（2009,2010） in two places（Henan, Jiangsu）. 【Result】The average fortified recoveries in cottonseed, leaf of cotton and soil were 73.50%-105.66%,with the relative standard deviation of 3.25%-9.89%. The limit of detection of the analytical method was 2.5×10-11g, and the lowest limit of quantification was 0.013, 0.012 and 0.005 mg/kg in cottonseed, leaf of cotton and soil, respectively. The dissipation half-lives of chlorpyrifos in cotton leaf and soil were 3.0-4.0 d and 6.2-8.9 d, respectively. The final residues of chlorpyrifos in cottonseeds were all ≤0.026 mg/kg in different sampling intervals and application frequencies. 【Conclusion】Chlorpyrifos is easily dissipated with low residues in cottonseed, so it can be safely used in cotton crops when the dosage is below 562.5 ga.i./ha, by spraying 3 times with the interval of 21 d.