Study on the Method of Residue Analysis and the Residue Dynamics of Myclobutanil 12.5%EC in Pear Fruit and Soil

An method of residue analysis and residue dynamics of myclobutanil in pear and soil were studied.Samples were extracted from pear and soil with methanol,and cleaned up by a column made up of neutral alumina,then determined by GC with ECD detector.The minimum detectable quantity of myclobutanil was 2.5×10-11g,the minim umdetectable concentration of myclobutanil in pear and soil sample was 0.005 and 0.003 mg/kg.The average recoveries and coefficients of variation of the method were 80.80%-93.81% and 1.87%-4.96% respectively.The result showed that myclobutanil degraded rapidly in the pear,but lowly in the soil relatively.The half-life of myclobutanil in the former was 2.86-4.75 d and in the latter was 15.79-24.17 d.And the last application was done in the 7th day before harvesting,the residue of myclobutanil in the harvested pear was lower than 0.5 mg/kg,demonstrating that it was safe to apply myclobutanil in pear with the recommended rate.