Different mathematical models with different degrees of complexity have been proposed to model affinity chromatography. In this work, in particular, a general rate model has been studied that considers axial dispersion, external film mass transfer, intraparticle diffusion, and kinetic effects investigating the influence in the simulations of two different relationships between the properties of the mobile phase and the affinity of different proteins to the ligand bound to the matrix. Two systems were used: Blue Sepharose and Protein A. With Blue Sepharose, an increasing linear salt gradient was used, and with Protein A, a decreasing semi-linear pH gradient. The kinetic parameters obtained in each of the two elution (adsorption/desorption) relationships studied (a power law type and an exponential type) led to very good agreements between experimental and simulated elution curves of mixtures of proteins finding that for more symmetrical peaks, the preferred elution relationship should be the exponential one, in contrast to the more asymmetrical peaks which shapes are better simulated by the power law relationship. Copyright © 2012 John Wiley & Sons, Ltd.