IgG adsorption on a new protein A adsorbent based on macroporous hydrophilic polymers: II. Pressure–flow curves and optimization for capture

Pressure–flow curves are obtained for a new protein A adsorbent matrix based on macroporous hydrophilic polymer beads with average diameter of 57 μm and a narrow particle size distribution. Experimental data are obtained in a 1 cm diameter laboratory column and in preparative scale columns with diameters of 20, 30, and 45 cm. The results are consistent with a model that assumes a linear relationship between bed compression and relative flow velocity. Surprisingly, the packing compressibility is essentially independent of column diameter for the preparative columns. As a result, after accounting for the variation in extraparticle porosity caused by compression, the column pressure drop is accurately predictable using the Carman–Kozeny equation. A model is also developed to predict productivity for IgG capture as a function of operating conditions based on dynamic binding capacity data presented in Part I of this work. For typical conditions, the model predicts maximum productivity at low residence times, between 1 and 1.5 min, when the dynamic binding capacity is at about 70–80% of the maximum. Combining the two models for column pressure and for dynamic binding capacity allows the design of preparative scale columns that maximize productivity while meeting specified pressure constraints.