Residue behavior and long-term dietary risk assessment of iprodione in shallot

Supervised field trials were conducted in Shandong, Anhui, Guangxi, Hebei, Heilongjiang and Henan province in 2018. A highly efficient and simple method was developed for the determination of iprodione in shallot using gas chromatography-mass spectrometry (GC-MS). The samples were extracted with ethyl acetate, purified with primary secondary amine (PSA), octadecylsilane (C₁₈) and graphitized carbon black (GCB), and detected by GC-MS. A good linear relationship between the peak area and the concentration of iprodione was observed in the range of 0.02-20 mg/L with the correlation coefficient greater than 0.99. The recoveries of iprodione in shallot ranged from 81% to 96% with the RSDs of 3%-9% at the spiked levels of 0.05, 0.5 and 20 mg/kg. The limit of quantitation of iprodione was 0.05 mg/kg. Results showed that the dissipation of iprodione in shallot fitted to the first order kinetics with the half-lives ranged from 12.2 to 15.8 d. The 255 g/L suspension concentrate (SC) of iprodione was sprayed at 750 and 1125 g a.i./hm² for 2-3 times on shallot. Then samples were taken and determined at 3, 5, 7 and 14 d after the last application. Results indicated that the residue of iprodione in shallot was 2.53-15.6 mg/kg. Finally, the long-term dietary risk assessment was conducted using the principle of risk maximization. The results revealed that the national estimated daily intake (NEDI) of iprodione was 2.0650 mg for general population, accounting for 54.6% of the acceptable daily intake, which demonstrated that the terminal residue of iprodione in shallot would not cause unacceptable risk to the health of the general population.