Ternary magnetic Fe3O4@C3N4@covalent organic framework for facile extraction and determination of organophosphorus pesticides in fruit

In this study, a magnetic composite material was prepared based on covalent organic framework (COFs) materials for the detection of trace organophosphorus pesticides. Fe3O4@C3N4@COFs were synthesized by a layer-by-layer assembly strategy and applied to the selective identification, detection and removal of profenofos pesticides using magnetic solid-phase extraction technique. After seven regeneration cycles, the composite exhibited excellent selectivity and affinity for profenofos, and eventually still achieved an extraction efficiency higher than 75%. Under optimized conditions, the proposed magnetic solid-phase extraction method coupled with high-performance liquid chromatography-tandem mass spectrometry showed a low limit of detection (1 × 10−5 μg/mL) for profenofos. The developed method was successfully used to detect profenofos in spiked fruit samples with satisfactory recoveries (74.33% −116.59%) and relative standard deviations (0.27% −7.41%). This study highlights the potential of COFs-based magnetic composites in sample pretreatment for targeted analysis and is a novel pathway for efficient sample preparation in food safety analysis.