Design of affinity membrane chromatographic columns

Abstract

A method for af®nity membrane column design, based on the analytical solution of the Thomas model for frontal analysis in membrane column adsorption, was developed. The method permits to ®nd the operating conditions to reach a 93.5% of the column capacity as operating capacity, using a sharpness restriction for the system breakthrough curve.The solution of the model is presented in a graphic form and can be used in a wide range of operational conditions, provided that four design restrictions are ful®lled. The application of the method was illustrated using experimental data and a simple procedure. The implications of the results on the design and optimiztion of af®nity membrane chromatographic columns are discussed. List of symbolsA membrane column cross-sectional area, cm 2 c solute concentration in the bulk phase, M c 0 solute concentration in the bulk phase at column inlet, M c à solute concentration in the bulk phase at equilibrium, M I 0 modi®ed zero-order Bessel function of the ®rst kind d p average pore diameter, cm D diffusion coef®cient, cm 2 s À1 F volumetric¯ow-rate, ml min À1 k 1 forward adsorption rate constant, M À1 s À1 k À1 reverse adsorption rate constant, s À1 K d dissociation constant, M L length of membrane column, lm L m membrane thickness, lm n dimensionless number of transfer units for overall process P molecule of protein PS complex between protein and ligand adsorbent q average protein concentration, M q à adsorbate concentration at equilibrium, M q m maximum binding capacity of the membrane, based on the solid volume, M r dimensionless separation factor S ligand adsorption site t time, s z axial distance along the membrane column Greek letters vtY L dimensionless solute concentration e void fraction C dimensionless ef¯uent volume s dimensionless time v linear velocity, cm s À1 IntroductionAf®nity membrane chromatography is a novel puri®ca-tion method that exploits the biospeci®c interactions between a protein and a ligand to economically purify proteins present at very low concentrations in complex solutions [1]. Af®nity membranes were developed to overcome the limitations encountered in conventional commercial processes using beads [2±5]. Af®nity membranes operate in convective mode, which can signi®-cantly reduce diffusion limitations commonly encountered in column chromatography. As a result, higher throughput and faster processing times are achieved in membrane systems [6]. Axial and radial diffusion, sorption kinetics, and nonuniformities in membrane porosity and thickness have been shown to affect af®nity membrane performance key factors such as breakthrough curve (BTC) sharpness and residence time. Degradation of membrane performance can be minimized working with axial Peclet number greater than 40, and radial Peclet numbers smaller than 0.04. Stacking more than 30 membranes averages outmembrane porosity and thickness nonuniformities [7]. Under these conditions, the membrane system performance can be predicted using the analytic solution of the

Breakthrough performance of stacks of dye-cellulosic fabric in affinity chromatography of lysozyme

“…In these chromatographic supports not without limitations, pore and film mass transfer seems to dominate the overall mass transfer resistance, in contrast to previous work, where these effects where not observed because the membrane pore size was too small [12,14]. One of the consequences of mass transfer limitations in these large-pore-size membrane systems is that, in order to meet a 70% of BTC sharpness criterion [15,16], the required residence time of the liquid in the membrane system has been estimated as 13 h, which is too high to be practical [12].…”

Analysis of Protein Purification Using Ion-Exchange Membranes

“…Modeling efforts for ion-exchange membrane chromatography have typically used the Langmuir-type second-order reversible rate equation to describe the kinetics of adsorption . These models were developed and work well for affinity membrane chromatography where the intrinsic association kinetics between the soluble protein and the immobilized ligand typically limit the binding rate. − However, for ion-exchange membrane chromatography, association kinetics are much faster than diffusive mass transport and are not rate-limiting steps . Therefore, models developed for affinity membrane chromatography are generally inappropriate for ion-exchange membrane chromatography.…”

“…2 These models were developed and work well for affinity membrane chromatography where the intrinsic association kinetics between the soluble protein and the immobilized ligand typically limit the binding rate. [3][4][5] However, for ion-exchange membrane chromatography, association kinetics are much faster than diffusive mass transport and are not rate-limiting steps. 6 Therefore, models developed for affinity mem- In the work of Sarfert and Etzel, 7 to obtain an analytical solution, both the dimensionless solute concentration in the solid phase (as suggested by Hiester and Vermeulen 8 ) and the overall mass-transfer coefficient were assumed constant.…”

Cellulose and Glass Fiber Affinity Membranes for the Chromatographic Separation of Biomolecules

“…On the other hand, membrane separation allows processing of a large amount in a relatively short time as a result of its internal structure that ensures a rapid reaction kinetics (4). The affinity membrane, which combines a high processing rate with a selective affinity adsorption, has proven to be more efficient than the classical column affinity method (5–27). Theoretical analysis showed that, compared to column chromatography, there are two major advantages in using membranes as stationary phases: First, in the membrane chromatography, the interaction kinetics between solute (target protein) and matrix (immobilized ligand) does not occur in the dead‐ended pores of the particles but in the through‐pores of the membrane where, as a result of the convective flow, the mass transfer resistance is tremendously decreased.…”