Residue characteristics and dietary risk assessment of mefentrifluconazole in grapefruit and orange under greenhouse conditions

This study was conducted to characterize terminal residue levels, residue decline patterns, and dietary risks of mefentrifluconazole in grapefruit and orange grown under greenhouse conditions.Residue analysis was performed using a validated liquid chromatography-tandem mass spectrometry method based on matrix-matched calibration.The analytical method showed satisfactory selectivity, linearity (R 2 >0.999), recovery (102.0-117.7%),precision (relative standard deviation ≤6.4%), and storage stability.Mefentrifluconazole was applied according to four treatment schedules, each consisting of three sequential applications before harvest.Residue levels gradually decreased as the interval between the final application and harvest increased for both crops.Mean terminal residue levels ranged from 0.286 to 0.426 mg/kg in grapefruit and from 0.202 to 0.420 mg/kg in orange.Terminal residue data were fitted to a first-order exponential model.The apparent half-life values estimated from these data were 38.5 days for grapefruit and 21.0 days for orange.Dietary risk assessment indicated that all percentages of the acceptable daily intake values were below 0.1%, suggesting that dietary exposure to mefentrifluconazole via grapefruit and orange consumption is unlikely to pose a health risk to consumers.These findings provide useful information for residue management and safe use of mefentrifluconazole in greenhousegrown citrus crops.