The Residual Dynamics In Cabbage And Soil And Hydrolysis Study Of Chlorpyrifos-Methyl

The residue kinetic of chlorpyrifos-methyl was studied in cabbage and soil. The residue dynamics of chlorpyrifos-methyl were presented by GC-FPD and GC-MS respectively. When high dosage 720g ai/ha water solution of 40% chlorpyrifos-methyl EC were applied in cabbage and soil, residues of chlorpyrifos-methyl in cabbage were 2.55~5.82 mg/kg, on soil was 0.61 ~ 1.22 mg/kg on hour 1 respectively, the half-life of chlorpyrifos-methyl was 0.4~ 1.0d on cabbage, 1.4~1.5d on soil respectively, the degradation rate was more than 90% on the cabbage after 3 days, 98% on the soil interval 14 days. The results showed that chlorpyrifos-methyl is easy to degrade in cabbage and soil.The final residual concentration of chlorpyrifos-methyl in cabbage and soil was determined. The results of two years showed that when 720g ai/ha water solution of chlorpyrifos-methyl EC was applied in cabbage and field for three times, interval three days and a week, the residual concentration in cabbage was 0.05 mg/kg and 0.006 mg/kg~0.01 mg/kg respectively. The result supports that the residual concentration was no relation with applying dosage and time. The residual concentration in soil was higher than in cabbage, the degradation rate in soil was slower than in cabbage; when they were increased of applying time and dosage, there was no accumulation of chlorpyrifos-methyl residues in soil.Through comparing and analyzing the GC-FPD and GC-MS analytical technologies, it has been studied of two kinds of superiority.The degradation and metabolism of chlorpyrifos-methyl at various buffer solution (at the same temperature) and temperature (at the same buffer solution) was studied. The results showed indicated that the degradation rate of chlorpyrifos-methyl was closely related to the pH value and temperature of aqueous solution. Chlorpyrifos-methyl could be degraded rapidly in basic aqueous solution. Under temperature of 25C and dark conditions, the half-life of chlorpyrifos-methyl at buffer solution of pH5.0,pH7.0 and pH10.0 is 16.5d,8.6d and 1.9d respectively. The degradation rate of chlorpyrifos-methyl increased quickly with the rise of temperature at the same buffer solution. Through analyzing and comparing the obtained mass spectra with the standard mass spectra could identify the degradation products.