Anion‐Exchange Chromatography ( HPIC )

The classical column chromatography on macroporous ion-exchange resins was a precursor of modern ion-exchange chromatography. The introduction of conductivity detection for ionic species added a new dimension to ion-exchange chromatography. The resins employed in ion-exchange chromatography carry functional groups with a fixed charge. In anion-exchange chromatography, quaternary ammonium bases are generally used as ion-exchange groups; sulfonate groups are used in strong acid cation-exchange chromatography. In addition to pure ion-exchange processes, nonionic interactions with the stationary phase are observed with certain ionic species. In some cases, even the separation of simple inorganic anions such as bromide and nitrate is entirely attained by various nonionic sorption properties. Such sorption phenomena may also be characterized thermodynamically. The ion-exchange capacity of a resin is defined as the number of ion-exchange sites per weight equivalent of the column packing. In addition of two phosphorothioate linkages results in four RNA isomers that can be resolved by anion-exchange chromatography using DNASwift SAX-1S.