Total residue levels and risk assessment of flufenacet and its four metabolites in corn

Abstract

Recently, a new formulation of flufenacet will be registered and applied to corn in China, but the residues of flufenacet and its metabolites in corn systems remain unclear. We developed a modified-QuEChERS (quick, easy, cheap, effective, rugged, and safe) method via high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) to detect flufenacet and its four metabolites FOE oxalate, FOE sulfonic acid, FOE alcohol and FOE thioglycolate sulfoxide in corn. The average recoveries were 75 %–106 % with the relative standard deviations (RSDs) of 2.8–14.7 %. The method was validated to be satisfied with the requirement of pesticide analysis. Under field conditions, the residues of flufenacet and its four metabolites in corn grain and fresh corn were all below 0.01 mg kg−1, and the total levels (the sum of flufenacet and its four metabolites) were less than 0.05 mg kg−1. In straw samples, the residues of these five analytes were no more than 0.089 mg kg−1, and the total residues did not exceed 0.24 mg kg−1. The residues levels, toxicological data of flufenacet and consumers’ dietary intake were used to calculate the intake risks for different populations. The risk quotients (RQc and RQa) were both lower than 100 % for all consumers, which indicated acceptable risks associated with the exposure to flufenacet in corn. Young people faced higher risks than adults, and gender differences were observed as well. Further studies will be conducted on the toxicity of metabolites of flufenacet to organisms in the future.