Surface Molecularly Imprinted Polymers on Multi-Function MnO2-Decorated Magnetic Carbon Nanotubes for Dispersive Solid-Phase Extraction of Three Fluoroquinolones from Milk Samples

A new kind of norfloxacin-imprinted polymer was prepared by the self-polymerization of dopamine on the surface of a multi-function MnO2 nanosheet-decorated magnetic carbon fiber (CF/Fe3O4/MnO2), denoted as CF/Fe3O4/MnO2/MIPs. These novel CF/Fe3O4/MnO2/MIPs displayed high binding capacity toward fluoroquinolones (FQs) due to the high specific area and thin imprinted layer. A new method employing dispersive solid-phase extraction, coupled with high-performance liquid chromatography (DSPE-HPLC), was developed for the determination of three FQs, norfloxacin, ciprofloxacin, and enrofloxacin. The presented method was linear over a calibration range of 5–1 × 104 μg/L, with detection limits ranging from 2.3 to 6.4 μg/L. The recovery of norfloxacin, ciprofloxacin, and enrofloxacin from milk samples ranged from 85.7 to 98.6%, with intra- and inter-day precision of less than 5.2%.