Preparation of Ofloxacin-Restricted Access Media–Molecularly Imprinted Polymers for Its Selective Recognition of Ofloxacin in Milk Samples

Abstract

In this study, a novel restricted access media–molecularly imprinted polymer (RAM–MIP) was prepared by precipitation polymerization using ofloxacin (OFLX) as a template, methacrylic acid as functional monomer, ethylene glycol dimethacrylate as the cross-linker and glycidyl methacrylate as pro-hydrophilic co-monomer for specific recognition and sensitive determination of trace ofloxacin in milk samples. The RAM–MIPs were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Then, recognition ability and hydrophilicity of RAM–MIPs were evaluated and the results indicated that the prepared RAM–MIPs exhibited excellent recognition ability and good hydrophilicity. Enrofloxacin, gatifloxacin, and sulfamerazine were used as competitive molecules to research the selective adsorption capacity of the RAM–MIPs. The maximum adsorption capacity of the RAM–MIPs for OFLX was 17.49 mg/g, which was almost double that of the non-imprinted polymers, RAM–NIPs. Under the same conditions, the binding ability of MIP to bovine serum albumin was calculated to be 31.19%, while RAM–MIPs was only 7.6%. Furthermore, a molecularly imprinted solid-phase extraction column was prepared with RAM–MIPs material and then reused ten times with a recovery rate above 75%. Combined with high-performance liquid chromatography analysis, this material can be used to effectively purify and separate OFLX from milk. This work was beneficial to eliminate the protein deposition and increased the simplicity and accuracy of analytical method for the determination of trace OFLX in milk samples.