Electrophoretic behaviour of quinolones in capillary electrophoresis - Effect of pH and evaluation of ionization constants

Quinolones are a family of antibacterial agents that are used extensively i n both human and veterinary clinics. Their antibacterial activity is pH-dep endent, and therefore an examination of protonation equilibria in quinolone solution is essential. In this work, dissociation constants of quinolones in water were obtained using capillary electrophoresis (CE). The method is based on measuring the electrophoretic mobility of the solute as a function of pH. Mobility and pH data are fitted using different models. These devel oped equations have two advantages. They permit the determination of pK(a) of analytes with the advantages of CE and also permit the prediction of the effect of pH on the electrophoretic behaviour of substances and then the p rediction of the pH optimum for the separation methods, using the minimum o f experimental measurements. (C) 1999 Elsevier Science B.V. All rights rese rved.