Development of magnetic COFs for simultaneous extraction and determination of aflatoxin B1 and benzo(a)pyrene

Aflatoxin B1 (AFB1) and benzo(a)pyrene (B(a)P) are representative co-occurring contaminants at trace levels in food samples. However, their simultaneous extraction and detection remain challenging due to differing polarities, low concentrations, and matrix interferences. Herein, a hydroxyl-functionalized imine-linked magnetic covalent organic framework (Fe₃O₄@COFs-DhaTab) was synthesized via a one-pot, room-temperature condensation. Fe₃O₄@COFs-DhaTab enabled a one-sorbent, one-workflow extraction of AFB1 and B(a)P via synergistic π-π stacking and hydrogen bonding. Fe₃O₄@COFs-DhaTab exhibited equilibrium adsorption capacities of 3.64 and 8.23 mg/g for AFB1 and B(a)P, respectively. Coupled with high-performance liquid chromatography, the method enabled simultaneous detection of both analytes with detection limits of 0.031-0.039 μg/kg. The method was validated across high-risk, matrix-diverse foods (edible oils, cereals, nuts, spices) and water, yielding recoveries of 84.4 %-113.6 % (AFB1) and 85.4 %-112.2 % (B(a)P). Fe₃O₄@COFs-DhaTab demonstrated excellent recyclability over three cycles. The cost-effective platform enables simultaneous extraction and quantification of co-occurring pollutants in complex matrices, enabling rapid and accurate multi-analyte analysis.