Full Characterization and Modelling of the Transport and Affinity-Adsorption of IgG in a Protein A Monolithic Column

The primary capture of monoclonal antibodies by Protein A affinity-chromatography packed beds is the preferred method used in the biotech industry. However, this operation suffers from several limitations such as high material and operational costs, diffusion as the primary transport phenomenon, and difficulties associated with packing and scale-up. The employment of convective-based chromatographic media could help to circumvent these operational limitations due to an appreciable decrease in pressure drops, increased mass transport rates, ease of packing, and overall reduced processing times. The work presented here characterizes the transport phenomena and adsorption of IgG in a commercially available convective interaction media (CIM) Protein A monolithic column. The moment analysis was used to determine the interstitial porosity and axial dispersion coefficient for several tracers covering a large range of molecular weights. The frontal analysis of characteristic points (FACP) approach has been successfully applied for the first time for monolithic media to determine the dynamic binding isotherm for human IgG. Elution was performed over several operating conditions to determine the effect of pH and flow rate on the total recovery of IgG, and concentration of the eluted fraction. A complete chromatographic model was used to fit the data for each section of the FACP assay. The chromatographic model accounts for all mass transport and intrinsic rate parameters of the solute including axial convection, longitudinal dispersion, adsorption and desorption rates at the surface of the solid phase, and the extra-column effects associated with the mixing volumes and delay times of the circuit. The model was used to simultaneously fit the IgG effluent data for all of the operating conditions investigated in order to determine the kinetic parameters associated with breakthrough and elution steps. The model showed a good agreement with the experimental data, elucidating both the predictive capability of the model and the reliability of the experimentally determined mass transfer parameters