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.

In this study, based on the structural features of seven carbamate pesticides, a urea-functionalized magnetic covalent organic framework materials (COFs) was synthesized using 4’,5’-bis(4-aminophenyl)-[1,1’:2’,1”-terphenyl]-4,4”-diamine (BATD) and 1,4-diisocyanatobenzene (PPDI) as monomers, and it was used as a sorbent for the magnetic solidphase extraction (MSPE) of carbamate pesticide residues. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed the successful modification of the material onto Fe₃O₄ nanoparticles. The extraction conditions were optimized, and the MSPE material was coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) to establish a sensitive and accurate method for the enrichment and detection of carbamate pesticide residues in honeysuckle flower (Lonicera japonica) and chrysanthemum flower (Chrysanthemum morifolium). The analytical method demonstrated good linearity (R² > 0.9962) in the concentration range of 2–100 µg/kg, with recovery rates between 76.90% and 109.86%. The limits of detection were 0.03–0.6 µg/kg, and the limits of quantification were 0.1–2.0 µg/kg.

A method was developed for the simultaneous determination of nine mycotoxins in wheat flour by ultra-high performance liquid chromatography-quadrupole/orbitrap high-resolution mass spectrometry (UPLC-Q/Orbitrap HRMS) combined with QuEChERS (quick, easy, cheap, effective, rugged and safe) pretreatment. Samples were extracted with acetonitrile/formic acid solution (98.0:2.0, V/V), salted out with a QuEChERS salt pocket, and then purified with a dispersive solid phase extraction (dSPE) tube. The target compounds were separated by UPLC and detected in the positive ion mode. Measured accurate mass-to-charge ratios of the nine mycotoxins were obtained in the full scan mode with a relative deviation not more than 1.91 × 10^-6 compared to the theoretical value, indicating accurate qualitative analysis of these compounds. A tandem mass spectral library for simultaneous screening and quantitation of the mycotoxins was built based on characteristic fragment ions. The linear ranges were 0.25–100 μg/L for all target analytes. The limit of quantification (LOQ) ranged from 0.30 to 3.00 μg/kg. Average recoveries at three spiked levels were in the range of 70.2%-112.0% with relative standard deviation (RSD) of 0.2%–4.5%. This method is useful for the high-throughput screening and confirmation of mycotoxins in wheat flour.