Computationally Guided Design of Magnetic Molecularly Imprinted Polymers for the Selective Determination of Pyrethroid Pesticides in Foods.

A magnetic molecularly imprinted polymer (MMIP) with high specificity for pyrethroid pesticides was successfully synthesized via a surface molecular imprinting strategy. Using fenvalerate as the template, density functional theory (DFT) calculations were performed to systematically evaluate four candidate functional monomers: methacrylic acid (MAA), acrylic acid (AA), 4-vinylpyridine (4-VP), and allyl-β-cyclodextrin (allyl-β-CD). Computational analyses revealed that allyl-β-CD yields a significantly increased imprinting factor, underscoring its superior capacity to confer adsorption selectivity. Binding energy calculations further elucidated the molecular recognition mechanism underlying the MMIP-template interaction. Comprehensive physicochemical characterization, including X-ray diffraction (XRD), scanning/transmission electron microscopy (SEM/TEM), and Fourier transform infrared spectroscopy (FT-IR), confirmed both the structural integrity and surface morphology of the resulting polymer. To demonstrate practical utility, MMIPs were employed in magnetic dispersive solid-phase extraction (MDSPE) for the simultaneous purification and enrichment of six pyrethroid pesticides (Pyrs) from apple and cabbage matrices. By coupling MDSPE with high-performance liquid chromatography‒tandem mass spectrometry (HPLC‒MS/MS), a robust analytical protocol was developed and validated for the determination of pyrethroid residues in fruits and vegetables. Recovery experiments across multiple fortification levels yielded mean recoveries of 72%-109%, with relative standard deviations (RSDs) of 0.65%-5.04%. This validated MDSPE-HPLC-MS/MS method provides a cost-effective and time-saving reliable analytical tool for routine monitoring of pyrethroid residues in fresh produce, contributing to improved food safety surveillance and regulatory compliance, and offering practical applicability for routine food safety monitoring laboratories.