IMMOBILIZED METAL AFFINITY-CHROMATOGRAPHY - MODELING OF NONLINEAR MULTICOMPONENT EQUILIBRIUM

A rigorous multicomponent isotherm for preparative immobilized metal a ffinity chromatography (IMAC) must consider the multipointed nature of adsorption, the possibility of steric hindrance of the stationary pha se upon binding of macromolecules, and the role of the mobile-phase mo difier. In this paper, the metal affinity interaction chromatography ( MAIC) model, a formalism which addresses all three of these issues, is presented. The linear and nonlinear adsorption behavior of proteins a s a function of mobile-phase imidazole content is considered. Numerica l simulations of nonlinear chromatography, employing MAIC equilibrium, are seen to accurately predict the experimental results in various mo des of nonlinear IMAC chromatography. In frontal chromatography, the m odel is seen to accurately describe the adsorption phenomena, includin g induced imidazole gradients. In step gradient and displacement chrom atography, the results presented in this manuscript demonstrate the ab ility of the MAIC model to predict multicomponent equilibrium in IMAC systems and establish this model as a powerful tool for studying the o peration of IMAC separations.