Ion chromatography, a specific liquid chromatographic technique, is a process that allows the separation of ions and polar molecules based on their charge properties. The separation mechanism involves retention of target ions based on ionic interactions resulting from the stationary phase surface (i.e. resin type inside an analytical column) that contain ionic functional groups that interact, or attract, target analyte ions of opposite charge. The chemistry of the stationary phase determines analyte affinity to the column and, ultimately the analyte retention time. Additionally, the analytical column provides stable support for stationary phase ions that serve as active sites in the dynamic ion exchange process. The mobile phase in ion chromatography, works to stabilize sample ions in solution and provide overall kinetic flow through the system. Eluents also provide counter ions to compete with active sites located on the surface of the stationary phase within the analytical column for retention/elution of target ions.

Ion chromatography is typically used to separate compounds generally considered non-volatiles, therefore making their analysis non-conducive to other traditional analytical techniques such as GC/MS or LC/MS.  A number of different detection systems are compatible with ion chromatography. These commonly include conductivity, uv/visible spectroscopy and mass spectrometric detectors.  When coupled with mass spectrometry, IC can yield additional molecular elucidation by providing mass-to-charge (m/z) data, thus increasing confidence of ionic identification.

Typically, IC systems are benchtop instruments.  It is a mature technology that is available from a number of different instrument manufacturers with prices typically $50,000 and up.