Residue dissipation and dietary risk assessment of trifloxystrobin, trifloxystrobin acid, and tebuconazole in wheat under field conditions

The dissipation and residues of trifloxystrobin and tebuconazole in wheat under field conditions were investigated using high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) after QuEChERS extraction. The method was validated using blank samples spiked at different treatment levels. The recovery rates of trifloxystrobin, trifloxystrobin acid, and tebuconazole in wheat grains, wheat plants, and straw ranged from 82% to 109%. The relative standard deviations (RSDs) ranged from 0.4% to 14%. The half-lives of trifloxystrobin and tebuconazole in wheat plants were 5.8-7.6 and 6.1-8.9 d. A terminal residue analysis showed that a dose of 144 g a.i. ha(-1) applied twice at an interval of 7 d resulted in the maximum residue levels for trifloxystrobin and tebuconazole in wheat grain samples 28 d after the last application (i.e. 0.023 mg kg(-1) and 0.047 mg kg(-1), respectively). The median residue levels were 0.02 mg kg(-1) and 0.01 mg kg(-1), respectively. The risk quotients (RQ) for trifloxystrobin and tebuconazole in wheat grains were 0.0011 and 0.00073, respectively, which were significantly lower than RQ = 1. The total RQ values for trifloxystrobin and tebuconazole in all registered crops were 0.10415 and 0.36859, respectively, which were also lower than RQ = 1. Based on this analysis, trifloxystrobin and tebuconazole residues in wheat grains would not affect the health of the general population in China.