Residual pattern of fenhexamid on pepper fruits grown under greenhouse conditions using HPLC and confirmation via tandem mass spectrometry

Fenhexamid (25%, SC) was sprayed on pepper fruits grown under greenhouse conditions at the recommended dose rate of 20 g/20 L water. Fruit samples were collected randomly at 0 (2 h after application), 1, 2, 4, 6, 8, 11, and 14 days post-application. The samples were extracted with acetonitrile, partitioned with water, passed through a cleanup procedure, and analysed via HPLC. Residues were confirmed via LC–tandem mass spectrometry (LC–MS/MS) in positive-ion electrospray ionisation (ESI+) mode. The rate of disappearance of fenhexamid on pepper fruits was described as first-order kinetics (r2 = 0.992) with a half-life of 4.7-day. Based on the pattern of decline of the fungicide residues in relation to the estimated maximum residue limits (MRL = 5 mg/kg), a safety pre-harvest interval of 1 day is suggested for peppers at the recommended dosage.