Chiral separation and determination of ofloxacin enantiomers by ionic liquid-assisted ligand-exchange chromatography

Abstract

A simple and accurate method for the separation and determination of ofloxacin enantiomers was developed by ionic liquid-assisted ligand-exchange high performance liquid chromatography. Both achiral and chiral ionic liquids were tested for their efficiency of ofloxacin enantiomeric separation. The effects of ligands, concentration of metal ion, organic modifier, pH of the mobile phase, and temperature were also investigated and evaluated. Optimal conditions were obtained on a conventional C₁₈ column, where the mobile phase consisted of methanol/water (20 : 80, v/v) (containing 4.0 mmol L⁻¹amino acid ionic liquid and 3.0 mmol L⁻¹copper sulfate) at a flow rate of 0.5 mL min⁻¹. Under this condition, the ofloxacin enantiomers could be baseline separated within 14 minutes; the proposed method was used to analyze different commercial ofloxacin medicines.