Adsorption behaviors of neutral and ionizable compounds on hybrid stationary phases in the absence (BEH-C18) and the presence (CSH-C18) of immobile surface charges

► The adsorption behavior of caffeine and nortriptyline was studied on two RPLC/hybrid phases. ► The bands were eluted with a low ionic strength buffer. ► The band profiles of these compounds were recorded under overloaded conditions. ► The adsorption isotherms and band profiles on both columns are accounted for suitable models. ► The results inform on electrostatic repulsion influence on retention of ionizable compounds.