Prediction of electrophoretic mobilities in non-aqueous capillary electrophoresis: Optimal separation of quinolones in acetonitrile–water media

A model of electrophoretic behaviour is used to predict the optimum conditions for the separation of a series of quinolones zwitterionic substances in mixtures of acetonitrile–water up to 30% (w/w) of acetonitrile. The effect of pH, pKa, the electrophoretic mobility of protonated and anionic species, and activity coefficients on the electrophoretic behaviour of quinolones is considered. The model proposed allows the resolution between substances in acetonitrile–water mixtures to be predicted from a few experimental data and thus permits one to obtain the best experimental conditions for separation methodologies.