Preparation of Magnetic Surface-Imprinted Polymer Microspheres with Hydrophilic External Layers for Selective Extraction of Fluoroquinolones from Eggs

A novel method of one-pot covalently grafting a hydrophilic organic polymer imprinted layer on the surface of magnetic microspheres was developed for the preparation of restricted access materials–molecularly imprinted magnetic microspheres (RAM-MIMMs) with water compatibility and ability to exclude biomacromolecules and selectively enrich analytes. The magnetic nanoparticles were coated with silica gel, modified with vinyl groups, polymerized with the template (enrofloxacin), functional monomer (glycidyl methacrylate, methacrylic acid), and cross-linking agent (ethylene glycol dimethacrylate) in chloroform, and then the hydrophilic surface was formed by a ring-opening reaction. The RAM-MIMMs were characterized by transmission electron microscopy, FT-IR spectroscopy, and adsorption experiments and demonstrated average diameters around 400 nm and a coating thickness in the range of 50 nm. They exhibited high selectivity of the imprinted cavities and hydrophilicity of the external surface with water compatibility and exclusion of biomacromolecules. The RAM-MIMMs were used for the magnetic dispersion microextraction of fluoroquinolones from egg samples with satisfactory results.