Adsorption models in chiral chromatography

The review delivers the analysis of the literature data on adsorption equilibrium in chiral systems. Chiral adsorbents usually comprise several groups of nonselective and enantioselective active sites. Each group may be heterogeneous in itself. A dynamic equilibrium between different conformations of chiral selectors, nonstoichiometric adsorption, and various secondary equilibria also contribute to the complexity of the phenomenon. In this context, the practice of the use and the limitations of the conventional single-site and two-site models of chiral stationary phase were considered. Special attention was given to problems of the interpretation of experimental results and rational approaches to the selection of physically meaningful adsorption models. The effect of chirality on mass transfer kinetics was also considered, although available information is limited and sometimes ambiguous in order to make solid conclusions.

► We discuss popular models of chiral stationary phase (CSP).
► A number of experimental data were reviewed, classified, and tabulated.
► The two-site model not always reflects a real complexity of CSP.
► Chiral selectors can be both enantioselective and nonselective sites.
► Heterogeneous models must describe enantioselective adsorption kinetics.