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Abstract

The simulated moving bed (SMB) technology is a proven tool for efficient separation of binary compound mixtures. However, the reliance on isocratic conditions limits the applicability of the classical SMB approach when considering the emerging field of bioseparations. Here the use of gradients opens up new possibilities. In its basic form a gradient in a SMB process can be established by using different solvent strengths in feed and desorbent, resulting in two plateaus of solvent strength. Typically the lower solvent strength can be found at the feed inlet. When compared to the conventional process the overall amount of solvent needed can be reduced and more concentrated product streams can be obtained. In this contribution two case studies will be presented. At first as a model system the separation of bovine IgG from lysozyme and/or bovine serumalbumin (BSA) will be analyzed. Antibodies are a common target substance in biochromatography as therapeutic monoclonal antibodies are among the most promising biopharmaceuticals. Using adsorption data obtained from single column experiments the design of an appropriate SMB process was possible. Gradient SMB separations were performed using ion-exchange and hydrophobic interaction matrices. With both interaction mechanisms it was possible to obtain pure fraction of IgG. The second target component is the active dimeric form of the bone morphogenetic protein-2 (BMP-2), which is to be separated from its inactive monomeric form as well as from other undefined contaminants [2]. BMP-2 is one of the most interesting growth factors from the transforming-growth-factor-β (TGF-β) superfamily. Gradient SMB separation was performed using prepacked HiTrap^TM Heparin HP columns. The presentation will show the dependence of the equilibrium functions of the two components studied on the ionic strength. This information provides the basis to choose suitable operating conditions for step-gradient-SMB processes using 3 or 4 zones. Experimental results obtained using a lab-scale SMB unit will be presented. [1] Keßler, L.C., Seidel-Morgenstern, A.: Purification of Immunoglobulin G using different matrices in simulated moving bed chromatography (Poster), ISPPP 2006, October 17 – 20, 2006, Innsbruck, Austria. [2] Gueorguieva, L., Vallejo, L.F., Rinas, U. & Seidel-Morgenstern, A. , J Chromatogr A 1135 ( 2006) 142.