Laboratory environmental fate studies are an important part of pesticide development. The studies provide information on metabolic pathways, rate of degradation for parent compounds and metabolites, metabolites that require toxicology evaluation and analytes to include in analytical methods. An aerobic soil degradation study was conducted using radiolabeled Meptyldinocap. Meptyldinocap degrades quickly in aerobic soil; the average laboratory DT<sub>50</sub> is approximately five days. Meptyldinocap degrades to three known major metabolites, X197324, X103317, and X12335709. Each of these major metabolites has an average laboratory DT<sub>50</sub> of less than 7 days. Additionally, the degradation of Meptyldinocap results in significant amounts of non-extractable residues (levels up to 45% applied radioactivity) and carbon dioxide (levels up to 53% applied radioactivity). Efforts to extract the non-extractable residues lead to the identification of a polar peak (levels up to 8.6% applied radioactivity). Polar radioactivity is a common degradation compartment in environmental studies, however polar radioactivity proves to be challenging to identify and characterize. Significant laboratory work was done to isolate, clean-up, characterize, and identify the polar radioactivity since it exceeded the EU identification trigger value. The extensive characterization showed the polar peak to consist of different components. The work also raised more questions about the nature of non-extractable residues and the nature of polar radioactivity in laboratory environmental fate studies. These questions regarding the nature of the polar radioactivity will be addressed during this presentation.

Aerobic soil degradation of 14C-meptyldinocap and identification of major metabolites

254th National Meeting (2017)

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