Design and preparation of novel magnetic covalent organic framework for the simultaneous preconcentration and sensitive determination of six aflatoxins in food samples.

An innovative core-shell covalent organic framework (COF), Fe3O4@COF (ETTBA-ND), was synthesized through a facile and energy-efficient method. This adsorbent facilitated magnetic solid phase extraction (MSPE) of six AFs prior to LC-MS/MS analysis, achieving one-step purification and enrichment in food matrices. The successful synthesis of the adsorbent was confirmed using various techniques, with adsorption capacities ranging from 46.7 mg/g to 52.3 mg/g. The adsorbent exhibited exceptional adsorption performance in real samples, with recoveries ranging from 80.3 % to 105.6 %, and notable reusability for more than seven cycles. The adsorption mechanism was investigated by density-functional theory and attributed to synergetic effects involving electrostatic and π-π stacking interactions. HPLC-MS/MS quantification revealed strong linear relationships within the 0.01-100 μg/kg range (R2 > 0.9983). The limits of detection ranged from 0.0016 μg/kg to 0.0099 μg/kg, indicating high sensitivity. The newly constructed COF adsorbents exhibit considerable potential for diverse applications in analytical fields that target various hazardous substances.