Preparation of a pyridyl covalent organic framework via Heck cross-coupling for solid-phase microextraction of perfluoropolyether carboxylic acids in food

•Pyridyl covalent organic framework (Py-COF) is prepared via Heck reaction.•Py-COF is used for the solid-phase microextraction of PFECAs from food.•Density functional theory is used to discuss the adsorption mechanism.•Py-COF efficiently extracts PFECAs based on the multi-interactions. The growing detection of emerging perfluoropolyether carboxylic acids (PFECAs) in food has raised considerable concerns about their high persistence, bioaccumulation, and toxicity. In this study, a pyridine-functionalized covalent organic framework (Py-COF) was synthesized by introducing basic pyridyl groups into Br-COF via Heck cross-coupling. According to density functional theory, PFECAs were adsorbed in the pore sites of Py-COF via O–···HN+ interaction, which was the stable and predominant adsorption configuration. After systematic characterization, Py-COF was used as the coating for solid-phase microextraction combined with high-performance liquid chromatography-tandem mass spectrometry (SPME-HPLC-MS/MS) for the efficient determination of PFECAs in food. Under the optimum conditions, the method showed satisfactory linearity (R2 ≥ 0.998), low limits of detection (0.001–0.004 ng g−1), and good relative recoveries (82.5 %–112 %). The established method was satisfactorily used for the analysis of trace PFECAs in food samples.