MODELING OF PREPARATIVE LIQUID-CHROMATOGRAPHY

In order to achieve an acceptable production rate at reasonable cost, preparative chromatography must be carried out with phase systems in which the kinetics of mass transfers and adsorption-desorption are fast. Accordingly, band profiles in overloaded chromatographic columns are best understood by considering the ideal model, while the process itself is most suitably modeled using the equilibrium-dispersive model. The former model assumes an infinite column efficiency, while the latter lumps the contributions of axial dispersion and mass transfer resistances into a single apparent dispersion coefficient. The properties and solutions of these models are reviewed. The conditions under which they give satisfactory results are summarized. The excellent agreement between the experimental band profiles of the components of binary mixtures and the individual band profiles calculated with the equilibrium-dispersive model is demonstrated. The degree of agreement is limited only by the accuracy with which the competitive equilibrium isotherms are accounted for.