Patent ID: 8513393

Claim:
A method for reducing the content of free Fc-moieties in a fluid comprising an Fc-containing protein and free Fc-moieties and having a pH of at least one unit below the isoelectric point (pI) of the Fc-containing protein, the method comprising cation exchange chromatography comprising the steps of loading said fluid onto a cation exchange resin to absorb the Fc-containing protein, washing the cation exchange resin with a first buffer having a conductivity of 8.2 to 9.2 mS/cm and a pH of 6.0 to 7.0 to remove free Fc-moieties, and eluting the Fc-containing protein with a second buffer to produce an eluate comprising the Fe-containing protein, whereby the level of free Fe-moieties in said eluate relative to the level of Fe-containing protein has been reduced from said fluid by a factor of 5 to 15.