Magnetic field-based separations using magnetic nano-and microparticles have received great attention for their superior characteristics such as good dispersability, the fast and effective binding of biomolecules, and reversible and controllable flocculation.[1-2] The sulfonamides are commonly used as antibacterial drugs in human medicine and animal feeds to fight infectious diseases.ial carcinogenesis and the antibacterial resistance.Therefore, sensitive and selective methods are required for monitoring sulfonamide residues to guarantee the safety of food.In this study, we prepared Fe3O4 magnetic nanoparticles (NPs) functionalized with the molecularly imprinted polymers (MIPs)[3] for sulfamethazine (SMZ).