A correction to the calculation of the Gibbs free energy of adsorption for biomolecules in ion-exchange systems

We wish to propose a correction to the methodology introduced by Gerstner et al. [J.A. Gerstner, J.A. Bell, S.M. Cramer, Biophys. Chem. 52 (1994) 97-106] for the calculation of Gibbs free energies of adsorption of biomolecules to ion-exchange systems. Our approach is based on the requirement that the mobile phase and stationary phase concentrations be expressed in exactly the same units and the equilibrium constant be strictly dimensionless. The Gibbs free energies of ion-exchange calculated based on this correction appear to be more negative than those originally calculated by Gertner et al.