High-crystalline magnetic covalent organic framework for rapid detection of fifteen polycyclic aromatic hydrocarbons in food

Establishing an accurate and efficient method to extract and determine polycyclic aromatic hydrocarbons (PAHs) in food samples is crucial to ensure human health. Herein, a highly crystalline core–shell magnetic covalent organic framework (MCOF-TpBD) is successfully synthesised. The material is comprised of Fe3O4 nanospheres as the magnetic carrier and a COF shell derived from the monomers 1,3,5-triformylphloroglucinol (Tp) and 1,4-benzenediamine (BD), achieved through a controlled transformation of an initial amorphous network. Combining a large specific surface area (564 m2 g−1), sufficient π-conjugation, and pronounced crystallinity, MCOF-TpBD is employed as an adsorbent for magnetic solid-phase extraction. Coupled with high-performance liquid chromatography with fluorescence detection, a rapid and accurate method is established for the extraction and determination of fifteen PAHs in smoked pork, wild fish, and soybean oil. With all conditions optimised, the established method provides low detection limits (0.012–0.968 μg kg−1), low quantification limits (0.064–3.230 μg kg−1), and satisfactory recoveries ranging from 74.4% to 95.0%. Collectively, these results confirm the applicability of the established approach. This work highlights the promise of crystalline MCOFs for efficient extraction of PAHs from complex matrices like food.