Enantioselection behaviors and risk assessments of chiral pesticide ethiprole and its chiral metabolite ethiprole amide in five kinds of vegetables

Ethiprole is a second-generation phenylpyrazole insecticide used in agricultural production as an alternative to fipronil due to its lower toxicity to bees. Ethiprole amide is chiral metabolite of ethiprole, but information regarding its formation and degradation in vegetables is limited. Here, the absolute configuration of ethiprole amide enantiomer was determined through circular dichroism, and the behaviors of chiral ethiprole and its metabolites in five kinds of vegetables were studied through field experiments. In these test vegetables, ethiprole amide concentrations were higher than ethiprole sulfone amide, with the maximum concentration found in celery. S-ethiprole was preferentially degraded in pakchoi and Chinese cabbage, and R-ethiprole amide concentration exceeded S-ethiprole amide. This assessment of enantiomer-specific behavior is crucial, considering that humans may be exposed to high residual levels of a specific enantiomer. Enantioselectivity should be taken into account when evaluating the risks associated with chiral pesticides and their metabolites.