Ion exchange chromatography, (IC) often just ion chromatography, is an analytical method in chemistry and biology. With the help of this chromatographic method, substances can be separated on the basis of their charge. A polymeric matrix contains charged functional groups that have reversibly bound counterions (cations in the case of cation exchangers and anions in the case of anion exchangers).

source https://de.wikipedia.org/wiki/Ionenaustauschchromatographie