Ion exchange chromatography involves two primary steps, first the binding of a
protein to a charged resin and second the elution or displacement of the protein from the charges of the resin. Critical to the former are the pH of the buffer used to equilibrate and load the proteins onto the column. Factors that control the elution are pH or ionic strength. Common ion exchangers include the positively charged anion exchanger - DEAE (diethylaminoethyl) and the negatively charged cation exchanger -CM (carboxymethyl). Review the references in the purification handout for good detailed references.