Abstract:

In order to cope with the differences in international trade regulations, it is necessary to establish a rapid non-targeted screening method for triazole fungicides in food. Therefore, a non-targeted method based on ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was established for the rapid screening of triazole fungicides in tomatoes. Tomato samples were extracted with acetonitrile and then purified by QuEChERS. The purified solution was separated on a BEH C₁₈ column (100 mm×2.1 mm, 1.7 μm) using a gradient mobile phase consisting of acetonitrile and water (both containing 0.1% formic acid). Full information tandem mass spectrometry (MS^E) acquisition using electrospray ion source under positive ion mode was performed. The 19 triazole fungicides were divided into eight groups based on their structural differences. The secondary mass fragments of eight typical standards in the eight groups of triazole fungicides were analyzed, and then, the regularities of the characteristic fragment ions and neutral loss fragments produced by collision-induced dissociation of the triazole fungicides were summarized. The fragmentation regularity was further verified by the other 11 triazole fungicides. A total of 16 tomato samples collected from local supermarkets in Beijing were screened using this non-targeted method. Diniconazole was identified and confirmed in one sample, which demonstrated that the method could achieve rapid and accurate non-targeted screening of triazole fungicides in tomatoes. The proposed method is highly efficient, sensitive, and accurate, thus providing a reference for screening triazole fungicide residues in food.

Key words: ultra-high performance liquid chromatography (UPLC), electrospray ionization (ESI), time of flight mass spectrometry (TOF-MS), triazole fungicides, fragmentation regularity, non-targeted screening