Polyoxometalate-ionic liquid functionalized magnetic nanocomposites for solid phase extraction and HPLC determination of sulfonamides in food samples.

Veterinary drug residues in animal-derived food products raise critical public health concerns, necessitating efficient extraction and detection methods to ensure food safety. In this study, novel Dawson-type polyoxometalate-ionic liquid (POM-IL) functionalized magnetic nanocomposites were synthesized for magnetic solid-phase extraction (MSPE) followed by high-performance liquid chromatography-ultraviolet (HPLC-UV) detection of sulfonamide residues, sulfamerazine (SMR), sulfamethazine (SMZ), and sulfamethoxazole (SMX) in milk, honey, and egg samples. The POM-ILs were immobilized onto Fe3O4@SiO2 nanoparticles to form MNP@POM-Q8IL and MNP@POM-Q10IL sorbents, which were characterized by FTIR, PXRD, SEM, and TGA analyses. The Q10-based composite exhibited superior adsorption efficiency, attributed to its longer alkyl chain that enhances hydrophobic interactions and molecular affinity while reducing matrix effects. The synergistic integration of POM, ionic liquid, and magnetic nanoparticle components enhances interfacial molecular recognition and adsorption efficiency, providing a rapid, reusable, and green platform for the sensitive HPLC determination of sulfonamide residues in food matrices. Under optimized conditions, the developed method showed excellent linearity (0.02-1000 µg mL-1), low detection limits (0.03-0.6 µg mL-1), high recoveries (up to 99%), and good reusability over eight extraction cycles. This work provides a rapid, green, and highly efficient analytical platform for the selective extraction and sensitive determination of veterinary drug residues in complex food matrices.