Effects of resin ligand density on yield and impurity clearance in preparative cation exchange chromatography. I. Mechanistic evaluation

The effects of resin ligand density on cation exchange chromatography performance in preparative monoclonal antibody purification processes were evaluated. A set of agarose-based cation exchange resins spanning a relatively wide range of ligand densities was tested using three different monoclonal antibodies with unique impurity profiles. Experiments were performed in bind-and-elute mode using gradient elution at both intermediate protein loadings and near saturation capacity. Ligand density did not affect clearance of high molecular weight variants under any of the conditions tested; however, ligand density did affect resolution of a basic charge variant in one case and changed host cell protein clearance in another instance. In general, the results indicate that the relationships between ligand density, retention, and resolution are affected by both characteristic charge and protein surface charge distribution.