Pore network modelling of affinity chromatography: determination of the dynamic profiles of the pore diffusivity of beta-galactosidase and its effecton column performance as the loading of beta-galactosidase onto anti-beta-galactosidase varies with time

A three-dimensional pore network model for diffusion in porous adsorbent pa rticles was employed in a dynamic adsorption model that simulates the adsor ption of a solute in porous particles packed in a chromatographic column. T he solution of the combined model yielded the dynamic profiles of the pore diffusion coefficient of beta -galactosidase along the radius of porous ads orbent particles and along the length of the column as the loading of beta -galactosidase onto anti-beta -galactosidase immobilized on the surface of the pores of the particles occurred, and, the dynamic adsorptive capacity o f the chromatographic column as a function of the design and operational pa rameters of the chromatographic system. It was found that for a given column length the dynamic profiles of the por e diffusion coefficient were influenced by (a) the superficial fluid veloci ty in the column, (b) the diameter of the adsorbent particles, and (c) the pore connectivity of the porous structure of the adsorbent particles. The e ffect of the magnitude of the pore connectivity on the dynamic profiles of the pore diffusion coefficient of beta -galactosidase increased as the diam eter of the adsorbent particles and the superficial fluid velocity in the c olumn increased. The dynamic adsorptive capacity of the column increased as (i) the particle diameter and the superficial fluid velocity in the column decreased, and (ii) the column length and the pore connectivity increased. In preparative affinity chromatography, it is desirable to obtain high thr oughputs within acceptable pressure gradients, and this may require the emp loyment of larger diameter adsorbent particles. In such a case, longer colu mn lengths satisfying acceptable pressure gradients with adsorbent particle s having higher pore connectivity values could provide high dynamic adsorpt ive capacities. An alternative chromatographic system could he comprised of a long column packed with large particles which have fractal pores, (fract al particles) that have high pore connectivities and which allow high intra particle dillusional and convective flock mass transfer rates providing hig h throughputs and high dynamic adsorptive capacities. If large scale monoli ths could be made to be reproducible and operationally stable, they could a lso offer all alternative mode of operation that could provide high through puts and high dynamic adsorptive capacities. (C) 2001 Elsevier Science B.V. All rights reserved.