Sepax SFC-SCX is a silica based mixed-mode strong cation exchange phase. The phase has a mixed chemical structure of sulfonic acid and phenyl group. The mixed mode of strong cation-exchange and hydrophobicity offers high selectivity and high resolution separation for cationic/basic and nitrogen containing compounds as well as desirable retention for a variety of weak cationic and neutral organic compounds. A uniform, polymeric bonding of SFC-SCX enhances its stability under various separation conditions.