Molecularly imprinted polymers for the solid-phase extraction of four fluoroquilones from milk and lake water samples

A method based on molecular crowding and ionic liquids as reaction solvents has been used for the synthesis of molecularly imprinted polymers. Levofloxacin was selected as the template, polymethyl methacrylate was the molecular crowding agent, and 1-butyl-3-methylimidazolium tetrafluoroborate (ionic liquid) was selected as the reaction solvent and porogen. The optimized proportion for the mixed porogen was dimethyl sulfoxide/ionic liquid/polymethyl methacrylate 1:1.6:5 in chloroform (150 mg mL(-1) ). The morphology and chemical composition of levofloxacin imprinted polymers were assessed by scanning electron microscopy and Fourier transform infrared spectroscopy. The absorption experiments demonstrated that the levofloxacin imprinted polymers possess high selective recognition property to levofloxacin and analogs, including enrofloxacin, ciprofloxacin and gatifloxacin, which all belong to fluoroquinolones. An extraction method using levofloxacin imprinted polymers as sorbent followed by high-performance liquid chromatography analysis was optimized for the determination of four fluoroquinolones in milk and lake water samples. Under the optimized conditions, good linearity was observed in a range of 5-1000 ng g(-1) with the limit of detection between 0.3 and 0.5 ng g(-1) for the four fluoroquinolones. The recoveries at three spiked levels ranged 82.4-98.3% with the relative standard deviation ≤4.9.