In case of ion exchange chromatography, resins or polysaccharides, e.g., cellulose, sepharose, having attached ionized functional groups are used for a high resolution separation of macromolecules, e.g., proteins. Gel filtration uses molecular sieves, composed of neutral cross linked carriers (e.g., polymers like agarose, dextrans) of different pore sizes.
Molecules smaller than the pore size enter the carrier and are retained; they are later eluted (in order of molecule size) and collected. Gel filtration is used in aqueous systems. Hydrophobic carriers are used for purification of hydrophobic molecules, e.g., many enzymes and other proteins.
