Separation and determination of quinolone antibacterials by capillary electrophoresis.

The migration behavior and separation of 13 quinolone antibacterials were investigated by capillary electrophoresis (CE). In order to predict the electrophoretic mobility, the protonation macroconstants of all the compounds were determined by pH-potentiometric titrations. We proved that the electrophoretic mobility of ionized quinolones (QNs) can be described with Offord's equation, and the migration order depends on their charge-to-mass ratios. A buffer of 25 mM sodium tetraborate adjusted to pH 9.3 was an efficient electrophoresis system for the separation of 12 QNs by capillary zone electrophoresis. This method can be considered a general method to separate quinolone derivatives. Ciprofloxacin, norfloxacin and ofloxacin, fluoroquinoles with very similar structural characteristics, were separated by micellar electrokinetic chromatography. Validation parameters, including linearity and detection and quantification limits, were also determined. Our results prove the applicability of CE for the simultaneous determination of QNs from complex mixtures. Our methods are environment-friendly replacement and improvement of a common high-performance liquid chromatography determination with rapid analysis time without using any organic solvents.