Determination of Residues of Quizalofop-p-ethyl and Its Metabolite in Adzuki Bean and Soil

A simple, efficient, rapid, low-cost and reliable method for the determination of herbicide residues by high performance liquid chromatography- photodiode array detection (HPLC-DAD) was established. The recoveries of quizalofop-p-ethyl and its metabolite quizalofop-p-acid were between 88.7 and 116.2%, and the relative standard deviations (RSDs) were between 0.82 and 4.39%. The limits of detection (LODs) were 0.005–0.008 mg/kg for quizalofop-p-ethyl and 0.003–0.01 mg/kg for quizalofop-p-acid. The limits of quantification (LOQs) were 0.015–0.02 mg/kg for quizalofop-p-ethyl and 0.01–0.03 mg/kg for quizalofop-p-acid. The method was reliable and stable. The residual quizalofop-p-ethyl and its metabolite quizalofop-p-acid in adzuki bean seeds, plants and soils from Zhangjiajie (Hunan) and Anda (Heilongjiang) were determined. Under different climatic conditions in central and northern China, the residual dynamics of quizalofop-p-ethyl in soils, plants and seeds of adzuki bean were studied. The results showed that the half-life of quizalofop-p-ethyl in adzuki bean plants and soils was between 3.4 and 6.7 d. The residues of quizalofop-p-ethyl and its metabolite quizalofop-p-acid in adzuki bean seed, plant and soil were determined to be lower than the maximum residue limit of 0.05 mg/kg.