Layer-by-layer fabrication of restricted access media-molecularly imprinted magnetic microspheres for magnetic dispersion microextraction of bisphenol A from milk samples

Abstract

A novel restricted access media-molecularly imprinted magnetic microsphere (RAM-MIMM) was prepared through layer by layer modification. The magnetic nanoparticles were coated with silica gel, modified with the amino group, coated by BPA-imprinted sol–gel film and grafted with the epoxy silane coupling agent. The RAM-MIMMs were characterized by SEM, TEM, FT-IR and adsorption experiments. The RAM-MIMMs were prepared with the average diameters of around 300 nm and the coating thickness in the range of 10–15 nm, and exhibited high selectivity (2.54) of the imprinted cavities and hydrophilicity of the external surface with water compatibility and exclusion biomacromolecules. The RAM-MIMMs were used for magnetic dispersion microextraction of BPA from milk samples. The average recoveries were obtained in the range of 85.2–98.6% with a precision of 2.2–4.6%. The limits of detection and quantitation of the proposed method were in the range of 4.70–10.51 μg kg⁻¹ and 15.65–35.02 μg kg⁻¹, respectively.