ABSTRACT
Reversed-phase/ion-exchange mixed-mode chromatography has gained increasing attention in recent years. The main driver is that such techniques provide control of selectivity through changes in the mobile-phase ionic strength, the pH, the organic solvent content, and/or the salt additives. As a result, options are now available to achieve optimal separations when compared to other separation modes, namely, reversed-phase liquid chromatography (RPLC), normal-phase liquid chromatography (NPLC), hydrophilic interaction liquid chromatography (HILIC), and ionexchange liquid chromatography (IEX-LC). The adjustable selectivity feature results from the fact that mixed-mode chromatography combines multiple retention modes in a single stationary phase, including RP/IEX, RP/HILIC, and IEX/HILIC combinations, each of which can be controlled independently.
