Abstract: To ascertain the dissipation and residues of fluazinam in green Chinese onion (Allium fistulosum L. var. giganteum Makion) and shallot (Allium ascalonicum), six independent field trials with 39.5% (V/V) fluazinam suspension were conducted during the crop year of 2017 in Beijing, Shandong, Inner Mongolia, Jiangsu, Sichuan and Ningxia of China. Fluazinam was extracted from samples with acetonitrile and subsequently cleaned-up with primary secondary amine, graphite carbon and octadecyl carbon sorbents prior to analysis by ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS). The quantification was performed by the external standard method. The results showed that the half-lives of fluazinam in green Chinese onion and shallot were 1.2 and 8.7 d, respectively. The final residues of fluazinam in them were < 0.010–0.308 and 0.100–5.738 mg/kg, respectively. There is no maximum residue limit (MRL) established in China for fluazinam in green Chinese onion and shallot. The MRLs set by Europe, Japan and Korea are 0.01, 0.1 and 3.0 mg/kg, respectively. According to the MRLs of Europe and Japan, the residues of fluazinam in green Chinese onion and shallot were unsafe. In this context, China should speed up the formulation of MRLs for fluazinam in green Chinese onion and shallot. This work will be useful for developing MRLs for fluazinam and ensuring the safe application of fluazinam in the future.

Key words: fluazinam, green Chinese onion, shallot, ultra-high-performance liquid chromatography-tandem mass spectrometry, pesticide residue