IgG Aggregate Removal by Charged-Hydrophobic Mixed Mode Chromatography

Charged-hydrophobic mixed mode chromatography methods have been applied to antibody purification for decades and have focused more recently on the specific task of aggregate removal. They exploit various combinations of alkyl and aromatic hydrophobic groups with positively and/or negatively charged residues. Charge and hydrophobicity remain relatively constant as function of pH for some ligands; one or both vary for others. All of these compound selectivities and their associated elution strategies are intended to achieve purification of native IgG through preferential retention of aggregates. This review focuses on the two members of this family that have shown the most promise for aggregate removal: MEP HyperCel and Capto adhere. It defines how they work, how they interact with various classes of biomolecules, how those interactions are controlled by different elution strategies, and how to determine which may be most effective for a particular antibody. Consideration is also given to their specific strengths and limitations from an industrial perspective.