Residue dissipation and dietary risk assessment of premix formulation of fluopyram, trifloxystrobin, and their metabolite in cucumber (Cucumis sativus L.) under field conditions

The premix formulation of fluopyram and trifloxystrobin is a broad-spectrum fungicidal combination that is widely used to manage foliar diseases in vegetable crops. However, concerns regarding its persistence and dietary exposure necessitate monitoring of residues under field conditions. The present study investigated the dissipation dynamics and dietary risk associated with fluopyram, trifloxystrobin, and its metabolite in cucumber (Cucumis sativus L.) following three foliar applications of fluopyram 250 + trifloxystrobin 250 g/L SC at the recommended (X, 600 mL ha⁻¹) and 1.25 × (750 mL ha⁻¹) doses. Residues were quantified using validated QuEChERS method with GC (trifloxystrobin and its metabolite) and GC–MS/MS (fluopyram), exhibiting excellent linearity (R² > 0.998), recoveries between 80 and 103%, and RSD < 10%, thereby confirming method reliability. Initial residues ranged from 0.412 to 0.555 mg kg⁻¹ for fluopyram, 0.348–0.561 mg kg⁻¹ for trifloxystrobin, and 0.158–0.218 mg kg⁻¹ for CGA321113. Dissipation followed first-order kinetics with half-lives (DT₅₀) of 2.25–2.69 days for fluopyram, 1.19–2.01 days for trifloxystrobin, and 1.14–2.11 days for CGA321113. The residues declined below the quantification limit (0.01 mg kg⁻¹) within 10–15 days after the final spray. Dietary exposure assessment, based on maximum residue levels, national consumption data and hazard quotient (HQ) values were below one for both the rural and urban people, indicating negligible chronic and acute risks. Overall, the fluopyram + trifloxystrobin premix demonstrates rapid dissipation and compliance with international food safety standards when applied according to good agricultural practices.