Developing chitosan-based magnetic functionalized porous polymer for effective extraction of benzoylurea insecticides from vegetables.

Herein, a novel chitosan-based magnetic bio-sorbent (M-Cs-BD@TBB) was synthesized through grafting chitosan with benzaldehyde (BD) and then crosslinking with 1,3,5-tris(bromomethyl)benzene (TBB) before modification with Fe3O4. Owing to the presence of multiple functional groups (-OH, -C=N, O, benzene ring), high porosity, and excellent wettability, M-Cs-BD@TBB demonstrated good adsorption performance for benzoylurea insecticides (BUs). Hydrogen bonding, π-π stacking, halogen bonding, and pore-filling were proved to be the potential adsorption mechanism. Moreover, the adsorption process of M-Cs-BD@TBB for BUs followed the Langmuir model and the pseudo-second-order kinetics model, indicating monolayer adsorption predominantly governed by chemical adsorption. Furthermore, M-Cs-BD@TBB exhibited remarkable utilization potentiality thanks to its outstanding preparation reproducibility, stability, and repeatability. Then, this reliable and innovative bio-sorbent coupled with high performance liquid-phase chromatography provided an attractive method for effectively trapping and detecting trace levels of BUs in food samples.