BIOSEPARATIONS WITH PERMEABLE PARTICLES

Permeable large-pore particles have many applications, in particular i n perfusion chromatography for bioseparations. The objective of this p aper is to elucidate the mass transport mechanisms in two commercial a dsorbents-POROS Q/M and Q Hyper D-and to answer the question if intrap article convection is present as a mass transfer mechanism. The paper contains three sections. In the first part, mass transfer inside porou s particles is discussed. The mass transfer mechanism which allows imp roved performance of perfusion chromatography is intraparticle convect ion. The combined effect of intraparticle convection and diffusion is an ''augmented'' effective diffusivity. This is the key concept to exp lain the peak sharpening and modified Van Deemter plots found with lar ge-pore particles. In the second part, column efficiencies in terms of HETP as a function of bed superficial velocity are experimentally mea sured for a non-retained protein (bovine serum albumine, BSA) in two a dsorbents: POROS Q/M (PerSeptive Biosystems) and Q Hyper D (BioSepra). In the third section breakthrough curves for both materials are measu red for a test protein (BSA) from which useful capacities and producti vities as a function of flow-rate are calculated. Experimental results indicate that intraparticle convection plays indeed an important role in both adsorbents.