Characterization of protein adsorption by composite silica-polyacrylamide gel anion exchangers .2. Mass transfer in packed columns and predictability of breakthrough behavior

Rates of uptake of proteins by a composite silica-polyacrylamide gel ion exchanger known as Q-HyperD are obtained for hydrodynamic conditions identical to those found in a chromatographic column operated at a high mobile phase velocity by means of a shallow bed technique. Under conditions of intraparticle mass transfer control, mass transfer rates in the shallow bed were the same as those measured when the sorbent particles were suspended in an agitated vessel, indicating that the intraparticle mass transfer rate is independent of the hydrodynamic conditions outside the particle and consistent with a purely diffusional transport mechanism. The predictability of breakthrough curves based on kinetic parameters obtained from batch experiments is assessed by comparing experimental results for different proteins with predictions of a model which incorporates the external film resistance and intraparticle diffusion. This model is in excellent agreement with the experimental results even at extremely high mobile phase velocities. Very large dynamic capacities are obtained with columns packed with Q-HyperD media as a result of their high static capacity, rapid uptake kinetics and mechanical strength that prevents compression of the particles even at elevated flow-rates.