A magnetic covalent organic framework as selective adsorbent for preconcentration of multi strobilurin fungicides in foods

A new method that utilizes a magnetic covalent organic framework (Fe3O4@BTA-TAPM) as a selective solid-phase extraction adsorbent has been developed for the simultaneous preconcentration of trace eleven kinds of strobilurin fungicides (SFs) in foods combined with ultra-high performance liquid chromatography-tandem mass spectrometry. The preconcentration conditions were optimized, including the adsorbent amount, extraction time, pH value, shaking time, elution solvent, desorption time and the interference ions. The maximum adsorption capacity of the adsorbent was ranging from 42.84 mg g-1 to 54.18 mg g-1 for eleven SFs. The low limits of detection were 0.003-0.072 μg kg-1. The recoveries of eleven SFs spiked at levels of 0.25-1000 μg kg-1 ranged from 80.2% to 109.3%, and the relative standard deviations were <6.8% (n = 3). The utility of the adsorbent was demonstrated to determine traces SFs in four different samples.