When performing ion chromatography the eluent mainly contributes to the selectivity of separation. Therefore different parameters have to be considered.
Ion strength The eluting ability increases with the ionic strength of the eluent.
pH value The retention time for anions of weak acids increases when the pH of the eluent is near the pKa value of the acid.
Temperature When increasing the temperature the ion exchange rate between stationary phase and mobile phase increases.
Flow rate On the one hand ions are eluted faster with high flow rates but on the other hand the separation efficiency will decrease.
Buffer salt Due to the pKa value the selectivity and eluting power are influenced by the anion of the eluent.