Effective extraction and detection of aflatoxins in cereals using nitrogen-rich benzodiimidazole linkage magnetic covalent organic framework based solid phase extraction and HPLC-MS/MS analysis

Cereals are frequently contaminated by aflatoxins (AFs). The objective of this study was to develop an efficient extraction materials for rapidly extracting and detecting AFs. A novel amino-functionalized benzodiimidazole linkage magnetic covalent organic framework (Fe₃O₄@BB-COF) was simply fabricated by one-step cyclization and aromatization. The Fe₃O₄@BB-COF, having multiple N-containing active sites, exhibited excellent extraction capability towards AFs due to synergistic interactions, including the π-π interactions, hydrogen bonding interactions, polar interactions, electrostatic interactions and Lewis acid-base interactions. The Fe₃O₄@BB-COF based MSPE method for detecting aflatoxins has advantages of simple operation, short extraction time (6 min), and low material consumption (2 mg). This method exhibited satisfactory linearity (0.05-20 μg/kg), and sensitivity (0.01-0.45 μg/L for the detection limits) and accuracy (76.8-97.1 % for recovery) and was successfully applied for extracting and detecting AFs in cereals.