DISSOCIATION-CONSTANTS AND PREFERENTIAL SOLVATION OF FLUOROQUINOLONESIN HYDROORGANIC MIXTURES USED IN LC

The examination of the protonation equilibria of fluoroquinolones is e ssential in order to understand their antibacterial activity. The pK v alues of three representative and widely used fluoroquinolones such as flumequine, norfloxacin and fleroxacin in some acetonitrile-water mix tures were obtained and correlated with the Taft and Kamlet solvatochr omic parameters, pi, alpha and beta. The pK values of antimicrobial q uinolones in any acetonitrile-water mixture up to 70% (w/w) can be cal culated from the relationships found and the most important solvent pr operties that affect electrolyte dissociation can also be evaluated. M oreover, variations in the pK values obtained over the whole compositi on range studied was explained by means of preferential solvation of e lectrolites in acetonitrile-water mixtures. (C) 1997 Elsevier Science B.V.