Characterization of dextran transport and molecular weight cutoff (MWCO) of large pore size hollow fiber ultrafiltration membranes

The development of vaccines, gene therapy agents, and virus-like particles has created exciting opportunities for the use of large pore size ultrafiltration membranes in downstream processing. One of the challenges facing both membrane producers and end-users is the difficulty in evaluating the membrane pore size or nominal molecular weight cutoff (MWCO) for the selection of appropriate membranes for targeted separations. We have used a combination of experimental measurements and theoretical modeling to develop an improved methodology for evaluating the MWCO of these large pore size ultrafiltration membranes based on dextran retention measurements. The model accounts for both concentration polarization effects and the intrinsic dextran retention behavior. The results not only provide fundamental insights into the factors controlling dextran retention, but they can also guide membrane manufacturers and end-users to the most appropriate conditions (i.e. feed flow rate and permeate flux) for evaluating the MWCO for hollow fibers with different geometry, pore size, and permeability.