Electrophoretic behavior of peptides in capillary electrophoresis: Influence of ionic strength and pH in aqueous–organic media

Through correct pH, pKa and activity coefficients values, a model describing the effect of pH on electrophoretic mobility of substances has been applied to a series of peptides in water and in acetonitrile–water mixtures. The derived equations permit prediction of the optimum pH for the electrophoretic separation from only a few experimental values and they also permit determination of pKa values of analytes in the aqueous–organic media employed. Furthermore, the electrophoretic resolution between pairs of substances can be predicted, in order to evaluate electrophoretic separations of the studied peptides.