Magnetic Molecularly Imprinted Polymer-Based Solid-Phase Extraction Combined with Ultra-high Performance Liquid Chromatography-Tandem Mass Spectrometry for the Determination of Four Aflatoxins in Peanuts and Soy Sauce

This study established a new method using magnetic solid-phase extraction (MSPE) based on a novel magnetic molecularly imprinted polymer (Fe₃O₄@MIP) combined with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for the rapid and sensitive determination of four aflatoxins (AFs) in peanuts and soy sauce. Using a surface grafting polymerization strategy, Fe₃O₄@MIP with selectivity for AFs was successfully prepared with 5,7-dimethoxycoumarin as a dummy template, methacrylic acid (MAA) as a functional monomer, and ethylene glycol dimethacrylate (EGDMA) as a cross-linker. Subsequently, the MSPE extraction conditions were systematically optimized. The results showed that the developed method had good linearity within the concentration range of 0.02-100 μg/kg (R² > 0.9915), with spiked recoveries in the peanut matrix ranging from 87.63% to 103.58%. Both intra-day and inter-day precision (relative standard deviation (RSD)) were below 8.16%, and the limit of detection (LOD) was as low as 0.0069-0.011 μg/kg. The prepared Fe₃O₄@MIP exhibited excellent selectivity and reusability for AFs. The MSPE-UPLC-MS/MS method is simple to operate and highly sensitive, and can effectively overcome matrix interferences, providing a reliable solution for the rapid and accurate detection of trace AFs in complex foods, and holding significant application value in the field of food safety monitoring.