Co-adsorption of Albumin and Immunoglobulin G from Human Serum onto a cation exchanger mixed mode adsorbent

Binary mixture adsorption containing Human immunoglobulin (IgG) and Human serum albumin (HSA) on a new cation exchanger mixed mode adsorbent (MabDirect MM) is assessed by batch, fixed bed and expanded bed adsorption experiments. Competitive adsorption isotherm was measured by batch experiment at the binding condition of pH 5.0 without salt where it was found that increasing the IgG concentration present in the solution (0–3 g dm−3) the HSA adsorption capacity decreases significantly (from 29.32 to 3.17 mg gdry−1) as a result of IgG competitive adsorption with HSA on MabDirect MM. Fixed bed adsorption experiments with binary mixture of HSA and IgG were performed at two flowrates. There is no roll up in the adsorption breakthrough curves even when it was increased the experiment timescale (from 2 to 0.7 mL/min at adsorption stage) which suggests that they are both adsorbed also on different sites at the binding condition, 20 mM citrate buffer pH 5.0 with 0.4 M⋅NaCl. Adsorption capacity for both proteins are in agreement with their respective single adsorption isotherms. Displacement experiments were carried out and showed that some amount of protein is released when the other protein is being fed to the column. Expanded bed breakthrough experiment with binary mixture of HSA and IgG shows an adsorption capacity (14.2 mgHSA gdry−1 and 6.3 mgIgG gdry−1) in good agreement with single protein batch experiments and also fixed bed adsorption for similar conditions. Regarding HSA and IgG desorption, it was obtained a HSA recovery of 62% and an IgG recovery of 39%.