PREPARATION AND CHARACTERIZATION OF MOLECULARLY IMPRINTED MONOLITHIC COLUMN FOR ON-LINE SOLID-PHASE EXTRACTION COUPLED WITH HPLC FOR DETERMINATION OF THE FLUOROQUINOLONE RESIDUES IN HONEY SAMPLES

A new ofloxacin-imprinted monolithic precolumn on-line coupling with reversed-phase high performance liquid chromatography was developed for the determination of the fluoroquinolone residues in honey samples. The molecularly imprinted monolithic column (MIP-MC) was prepared by in situ polymerization in a stainless steel chromatographic column, using methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, and chloroform and dodecanol as the mixed porogenic solvents. The optimal synthesis conditions and on-line extraction conditions were investigated. The maximum binding capacity (51.50 mg/g) and the dynamic binding capacity (434.92 µg/mL) of the MIP-MC were evaluated by Scatchard analysis and the breakthrough curves, respectively, and they are higher than the non-imprinted monolithic column (43.15 mg/g and 96.52 µg/mL). An enrichment factor of 15.4 along with a good sample cleanup effect was obtained under the optimized conditions. The recoveries of the method for three fluoroquinolones such as ofloxacin, ciprofloxacin, and enrofloxacin were investigated, and high recoveries of 82.0–90.2% from honey samples were obtained with precision between 2.5% and 6.9%. The limits of detection and quantitation of the proposed method were in a range of 5.68–9.71 (μg/kg and 18.93–32.37 (μg/kg, respectively. The method was successfully applied to on-line preconcentration, separation, and determination of the fluoroquinolone residues in food.