The MCI GEL ProtEx® series of columns for anion exchange separation of proteins is based on a unique, 5µ monodispersed, macroporous polymethylmethacrylate polymer. Before bonding with ion-exchange groups, the surface of the polymethacrylate particles is completely covered with a hydrophilic layer which is chemically stable. This extra layer of hydrophilic character completely removes any “trace” of hydrophobicity inherent in the methacrylate polymer, resulting in pure ion-exchange separation mechanisms, quantitative recovery of proteins, good mechanical stability, and excellent chemical stability. The 5µ monodisperse beads provide the high efficiencies required to separate protein isoforms and other structurally similar compounds.