Dissipation and Safety Evaluation of Pyraclostrobin in Apple and Soil

[Aims] Based on the method for the determination of pyraclostrobin in apple and soil, the dissipation dynamics and residues in apple and soil were investigated, and the safety of the application of this pesticide on apple was evaluated. [Methods] The samples were extracted with acetonitrile by ultrasound-assisted method, purified by primary secondary amine(PSA), and determined by high performance liquid chromatography equipped with ultraviolet detector(HPLC- UV). [Results] At fortified levels of 0.05-5.0 mg/kg, the average recoveries ranged from 90.8 to94.2%, with the relative standard deviations(RSD) of 0.9-2.1%. The limit of quantification(LOQ) was 0.05 mg/kg. The linearity was acceptable in the range of 0.1-7.5 mg/kg. The results showed that the half-lives(t1/2) were 15.4 and 16.5 d in apple, while 19.3 and 21.0 d in soil from Beijing and Anhui, respectively. The final residues of pyraclostrobin in apple were in the range of 0.08-0.16 mg/kg on 21, 28 and 35 d after the last application with the high level of recommend dose and times. [Conclusions] The pyraclostrobin residue in apple harvested at 35 d after the final application was below the maximum residue limit set by China(MRL, 0.5 mg/kg), therefore, the apple was relatively safe to human.