Dissipation Behavior and Residue Distribution of Famoxadone and Cymoxanil in Cucumber and Soil Ecosystem Under Open-Field Conditions

In this study, a practical and excellent method was used to determine the famoxadone and cymoxanil via high-performance liquid chromatography equipped utilizing ultraviolet detector lamp (HPLC-UV) for investigating the dissipation behavior and residue distribution of famoxadone and cymoxanil in cucumber and soil ecosystem. The limit of quantification (LOQS) of famoxadone and cymoxanil in cucumber were 0.50, 1.00, 2.00 and 0.05, 0.50, 1.00 mg kg−1 in soil, respectively. The limit of detection (LODS) of both famoxadone and cymoxanil were 8.0 ng. The average recoveries (n = 5) of the fungicide ranged from 84.10 to 108.02% with the relative standard deviations (RSDs) typically < 9.23%. The fungicide was applied to cucumber and soil at the range of doses (275.6–413.4 g a.i.ha−1) three or four times. The half-lives of famoxadone and cymoxanil in cucumber and soil were 1.34–16.12 days, which followed the first-order chemical reaction kinetics equation Ct = C0 × e-kt. The residues of famoxadone and cymoxanil in cucumber at the pre-harvest interval (PHI, 3 days) were below 8.0 × 10−8 g and 8.0 × 10−9 g, respectively. Overall, this study evaluated the food safety and the environmental fate of famoxadone and cymoxanil in cucumber and soil ecosystem. In addition, this study would promote the series of work on the pesticide exposure assessment of these fungicides as well.