Abstract:

To evaluate the safety of etoxazole, the dissipation and residue of etoxazole in loquat was studied under field condition, and dietary risk assessment was conducted. The sample was extracted by acetonitrile, purified with PSA and C₁₈, and determined by high performance liquid chromatography tandem triple quadrupole mass spectrometer (HPLC-MS/MS). The mean recovery of etoxazole in loquat was 89.2%-97.1% at the three spiking levels from 0.01 to 1.0 mg/kg, with relative standard deviations (RSD) of 3.4%-5.3%, and the limits of quantitation (LOQ) was 0.01 mg/kg. The half-life of etoxazole in loquat was 6.9-8.9 d. When 20% etoxazole SC was applied at the dosage of 33.3 and 50 mg/kg, for two and three times, respectively, the final residue of etoxazole in loquat was 0.055-0.37, 0.032-0.19 and 0.014-0.12 mg/kg at 14, 21 and 28 d after the last application. The residues of etoxazole in loquat gradually decreased with the extension of harvest interval. Assessing dietary risk found that the national estimated daily intake (NEDI) of etoxazole was 0.0126 mg, risk quotient (RQ) was 0.4%, and there was no unacceptable risk to the health of the general population.

Key words: etoxazole, loquat, residue and degradation dynamics, dietary risk assessment, HPLC-MS/MS