2. Stationary phases in ion chromatography

The stationary phase is the key element in a chromatographic system, as it plays a fundamental role in its separative power.

The stationary phases used in IC are synthetic ion exchange resins, made from high-molecular-weight polymeric materials containing numerous ionized functional groups. A stationary phase may contain either anionic functional groups (for cation exchange) or cationic functional groups (for anion exchange), enabling retention of the species to be separated. With a cation-containing stationary phase, anions progress through the column at different speeds depending on their charge, size and polarizability, while cations are not retained. The two main requirements of "high-performance" ion chromatography are, on the one hand, the use of dilute eluent solutions (very low Q) and, on the other, the use of highly efficient stationary phases enabling...