3. Mobile phase

Cl is mainly governed by ion exchange phenomena, possibly coupled with auxiliary reactions such as acid-base or complexation reactions. For this reason, the mobile phases are mainly aqueous solutions containing one or more electrolytes. The strength of the eluent in ion chromatography is determined by its ionic potential. The more ions an eluent contains, the faster the ion of interest will be eluted. For example, if the ion of interest is an anion, increasing the strength of the eluent has the effect of increasing the number of anions coming from the eluent to compete with the anion of interest for the limited number of cationic sites in the stationary phase. As a result, the anion of interest has fewer interactions with the stationary phase and is less retained by the column, resulting in faster elution.