Residue and chronic dietary risk assessment of penthiopyrad, trifloxystrobin and their metabolites in tomato by QuEChERS-high performance liquid chromatography-tandem mass spectrometry

A method was established for the simultaneous determination of penthiopyrad, its main metabolite 1-methyl-3-trifluoromethyl-1H-pyrazole-4-carboxamide (PAM), trifloxystrobin and its metabolite trifloxystrobin acid in tomato. The samples were extracted with acetic acid and acetonitrile, cleaned-up with anhydrous MgSO₄, primary secondary amine (PSA) and GCB, and detected by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The linearities of penthiopyrad, PAM, trifloxystrobin and trifloxystrobin acid ranged from 0.025 to 2 mg/L, with R²≥ 0.9992. The average recoveries of the four compounds in tomato at different spiked levels were 88%-97%, with the relative standard deviations (RSD) less than 3.9%. The limits of quantification (LOQs) of the analytes were all 0.05 mg/kg. The supervised residue trials were carried out in 12 farm regions in China according to "Guideline for the Testing of Pesticide Residues in Crops". The 30% suspension concentrate of penthiopyrad and trifloxystrobin was sprayed twice with an interval of 7 days at the recommended dosage of 270 g a.i./hm² at the early stage of Botrytis cinerea in tomato, and the recommended pre-harvest interval was 5 days. On the 5th and 7th day after the last application, the residues of penthiopyrad in tomato samples were below 0.26 mg/kg, and the residues of trifloxystrobin were below 0.33 mg/kg, which were lower than the corresponding MRLs set in China. The dietary risk assessment was carried out according to the results of residue field trials, dietary structure and toxicological data. The results showed that the national estimated daily intake (NEDI) of penthiopyrad and trifloxystrobin were 0.1382 mg and 0.2645 mg, respectively. The dietary risk quotient (RQ) of penthiopyrad and trifloxystrobin in tomato were less than 100%, which indicated that the application of the 30% suspension concentrate of penthiopyrad and trifloxystrobin under recommended Good Agricultural Practice (GAP) conditions would not pose an unacceptable risk to human health.