Ion Chromatography is a method for separating ions (Anions and Cations) based upon their interactions with resin (stationary phase) and the eluent (mobile phase). These phases differ between an anion column, which attracts anions, and a cation column, which attracts cations. IC separates ions and polar molecules based on their affinity to the ion exchanger. The two types of ion chromatography are anion-exchange and cation-exchange. Cation-exchange chromatography is used when the molecule of interest is positively charged.