Ion-exchange chromatography (IEC) is a laboratory separation process for the separation of ions and polar molecules based on their charge. It can be used for a multitude of charged molecules, including large molecules, such as proteins and oligonucleotides, and small molecules, such as amino acids. The stationary phase commonly consists of a resin or gel with a covalently linked charged molecule. Depending on the charge, IEC can be either anion- or cation-exchange chromatography. It is often used for protein purification, DNA/RNA oligomer analysis, and water analysis.
Ion-exchange chromatography is one of the oldest separation processes described in literature. In 1850, H. Thompson and J. T. Way treated various clays (= stationary phase) with ammonium sulfate or carbonate in solution to release calcium. During World War II, ion-exchange chromatography was further developed and played a crucial role in the “Manhattan project” to enrich radioactive...