Retention of ionizable compounds on high-performance liquid chromatography XI. Global linear solvation energy relationships for neutral and ionizable compounds.

A global linear solvation energy relationship (LSER) that simultaneously models retention in reversed-phase liquid chromatography as a function of solute LSER descriptors and mobile phase pH and composition has been derived from both the local LSER model and the linear solvent strength theory. At most only 13 mobile phase parameters and seven solute parameters are required to establish the global LSER model for neutral and ionizable solutes. This model implies only one mobile phase and two solute parameters more than the model previously set for neutral solutes. The additional mobile phase and solute parameters account for the ionization of the solute. The model has been successfully tested for 30 solutes of different type (acids, bases and non ionizable compounds) at 10 different pH values in three different acetonitrile-water mobile phases.