Dissipation patterns of pesticides are especially significant for understanding the potential exposure in the environment. It is important to predict the biological half-lives of applied pesticides to ensure safety. In this study, three kinetic models (zero order (ZO), first order (FO) and second order (SO)) were employed to compare and characterize the best-fit kinetic model describing the residual pattern of triazole pesticides in perilla leaves as a minor crop. Triazole pesticides are familiar to minor crops so in this study we used pesticides such as tetraconazole and tebuconazole. Tetraconazole (12.5%, EW) and tebuconazole (25%, EC) were diluted with water and sprayed 3 times at an interval of 7 days before harvesting. The residual amounts of tetraconazole and tebuconazole were analyzed by GC-ECD and HPLC-UVD respectively. Comparing the correlation coefficients (R2) of the kinetic models, tetraconazole was 0.97, 0.98, and 0.97 for the ZO, FO, SO respectively and tebuconazole was 0.90, 0.97, and 0.98 for the ZO, FO, SO respectively. Therefore FO was best fit to Tetraconazole but SO was best fit the dissipation patterns of tebuconazole. The equations of biological half-life of tetraconazole were 16.1 days using FO (Ct=10.939e-0.043x) but 14.5 days, 18.4 days using ZO and SO. Furthermore, tebuconazole half-life was 5.4 days using SO (Ct=0.0258x+0.1428) but 8.3 days, 6.8 days using ZO and FO. Therefore, kinetic models should be applied to assess the dissipation pattern of the residues for the accurate calculation of the biological half-life.

Application of kinetic models for degradation rate of triazole pesticides in perilla leaves

2019 Fall National Meeting

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