Residual Characteristics and Dissipation Kinetics of Fluxametamide in Lettuce Leaves and Roots

: This study evaluated the residual characteristics of the isoxazoline insecticide fluxametamide in lettuce leaves, roots, and soil under greenhouse conditions. The flux-ametamide residue analysis method used in this study showed excellent accuracy (84.7-116.0%) and precision (RSD ≤ 5.7%), satisfying the SANTE guideline criteria, and matrix effects were within ±20%. Fluxametamide was chemically stable at temperatures between – 70 and 40°C, but became vulnerable at temperatures above 60°C, with significantly reduced recovery. Residue levels decreased from 0.400 to 0.152 mg/kg in lettuce leaves and from 0.066 to 0.012 mg/kg in the roots over 10 days, while residues in soil were below the limit of quantification on the day of pesticide application. All fluxametamide residues in lettuce leaves were detected below the maximum residue limit (MRL; 10 mg/kg). The biological half-lives were 6.8 days in lettuce and 4.2 days in roots. When the dilution effect caused by crop growth was excluded, the half-lives were extended to 9.9 days and 7.2 days for lettuce and roots, respectively, although the dilution effect was less pronounced compared to rapidly growing crops. The results of this study may serve as fundamental data for the review of regulations, including MRLs and safety use standards, for fluxametamide in lettuce leaves and roots.