Dissipation, terminal residues and risk assessment of fluopicolide and its metabolite in cucumber under field conditions

In this study, the dissipation, terminal residue levels, and risk assessment of fluopicolide and its metabolite (2,6-dichlorobenzamide) in cucumber and soil under field conditions were investigated. An analytical method for the simultaneous quantification of fluopicolide and its metabolite in cucumber and soil using gas chromatography coupled with electron capture detection (GC-ECD) was developed. Recoveries were between 78 and 111 %, with relative standard deviations (RSDs) from 1.6 to 10.2 % at different spiked levels (0.01, 0.025, 0.5, and 2 mg kg−1). The limit of quantification (LOQ) was 0.01 mg kg−1. Fluopicolide exhibited half-lives ranging from 2.0 to 3.3 days and 35 to 63 days, in cucumber and soil under field ecosystem, respectively. The results suggested that the degradation of fluopicolide to 2,6-dichlorobenzamide was quite limited. During harvest, the terminal residues of fluopicolide and its metabolite were both below 0.13 mg kg−1, which were lower than the established temporary maximum residue limits (MRLs), 0.5 mg kg−1. The risk quotients (RQs) ranged from 0.0033 to 0.0078, which showed low risk for different groups of people in China. The present study may provide guidance on reasonable use of this pesticide and serve as a reference for establishment official MRLs in China.