Abstract: In the present study, magnetic separation method was combined with surface molecular imprinting. The magnetic molecularly imprinted polymer (MMIP) for chloramphenicol (CAP) was prepared by suspension polymerization method based on modified Fe₃O₄ nanoparticles as support material, CAP as template molecule, methacrylic acid (MAA) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as corss-linker and azobisisobutyronitrile (AIBN) as initiator. Meanwhile, the magnetic molecularly non-imprinted polymer (MNIP) was prepared accordingly with the absent of CAP. Each step of the products were characterized by Fourier transform infrared spectrometer, microscopic morphology of MMIP and MNIP were observed by scanning electron microscopy, and the saturation magnetic strength of magnetic nanoparticles and MMIP were detected by vibrating sample magnetometer. The adsorption capacity of MMIP and MNIP were studied by binding experiments. Methodology evaluation was performed for detecting chloramphenicol in foods by using MMIP as solid phase extractant. The obtained MMIPs were 400-700 nm in diameter and had good monodispersity. It could be rapidly separated under an applied magnetic field. The MMIP had high maximum apparent adsorption capacity which was up to 29.18 mg·g^-1 and good selectivity. It had high recovery (86.30%-94.21%), high precision (RSD≤1.53%), good stability (RSD≤1.87%) and low detection limit (3.0 μg·kg^-1), when MMIP was used as solid phase extractant. Thus,the MMIP could be used to detect the chloramphenicol residue in food.

Key words: chloramphenicol, magnetic separation, surface imprinting, solid phase extraction, high performance liquid chromatography