Assessment of the Dissipation Behaviors, Residues, and Dietary Risk of Oxine-Copper in Cucumber and Watermelon by UPLC–MS/MS

During production, agricultural products are often susceptible to potential harm caused by residual traces of pesticides. Oxine-copper is a broad spectrum and efficient protective fungicide widely used in the production of fruits and vegetables. The present study was carried out to profile the dissipation behaviors and residues of oxine-copper on cucumber and watermelon using QuEChERS pretreatment and UPLC–MS/MS. Its storage stability and dietary risk assessment were also estimated. The method validation displayed good linearity (R2 ≥ 0.9980), sensitivity (limits of quantification ≤0.01 mg/kg), and recoveries (75.5–95.8%) with relative standard deviations of 2.27–8.26%. According to first-order kinetics, the half-lives of oxine-copper in cucumber and watermelon were 1.77–2.11 and 3.57–4.68 d, respectively. The terminal residues of oxine-copper in cucumber and watermelon samples were within <0.01–0.264 and <0.01–0.0641 mg/kg, respectively. Based on dietary risk assessment, the estimated long-term dietary risk probability value of oxine-copper in cucumber and watermelon is 64.11%, indicating that long-term consumption of cucumber and watermelon contaminated with oxine-copper would not pose dietary risks to the general population. The results provide scientific guidance for the rational utilization of oxine-copper in field ecosystems of cucumber and watermelon.