Dissipation behavior and risk assessment of fungicide and insecticide residues in grape under open-field, storage and washing conditions

Abstract

The dissipation rate and risk assessment of penconazole, hexaconazole, diazinon, ethion and phosalone in grape under field (pre-harvest) and post-harvest conditions (storage at 4 and 25 °C) during 24 days and after washing (immersion) were determined. Pesticide residues were measured by gas chromatography/tandem mass spectrometry. The dissipation of pesticides followed first-order kinetics and their half-life (t1/2) under pre-harvest intervals (PHI) were less than those of post-harvest conditions. For penconazole, hexaconazole, diazinon, ethion and phosalone in grape, the t1/2 under the pre-harvest period was 7.22, 5.50, 2.36, 2.34 and 2.79 days, and the recommended PHI value was 15, 23, 12, 13 and 15 days, respectively. During washing, pesticide residues were decreased. Among washing solutions, sodium bicarbonate (2% w/v) was the most effective one in pesticide removal. After immersion (15 min) in this solution, the reduction of penconazole, hexaconazole, diazinon, ethion and phosalone was 94.47, 93.65, 95.39, 71.56 and 63.13%, respectively. In samples analyzed, the hazard quotient of all mentioned pesticides except diazinon was less than 1, indicating that the health hazard was negligible due to the intake of these pesticide residues through grape. The results presented valuable information regarding PHI and a suitable cleaning method for pesticide removal in grape.