Residues, dissipation and risk assessment of triazole fungicide tebuconazole in green onion (Allium fistulosum L.)

The dissipation and residues of tebuconazole in green onion (welsh onion and chive) in China were firstly investigated based on a quick, easy, cheap, effective, rugged and safe method (QuEChERS) combined with high-performance liquid chromatography-ultraviolet detector (HPLC-UV). In the method validation, the fortified recoveries ranged from 96% to 100% with relative standard deviations of <= 10%. The dissipation rate of tebuconazole follows the first-order kinetics, with the half-lives of 9.4-9.9 days. Based on the terminal residue test, a risk quotient (RQ) for dietary exposure assessment was carried out on green onions. The RQs for tebuconazole at pre-harvest interval (PHI) 7, 10 and 14 days were all less than 100%, which is acceptable for human consumption. The present study can provide a reference that establishes maximum residue limits (MRLs) of tebuconazole in green onion, which is not currently established in China.