Model of CE enantioseparation systems with a mixture of chiral selectors Part I. Theory of migration and interconversion

Theory of equilibria, migration and dynamics of interconversion of a chiral analyte in electromigration enantioseparation systems involving a mixture of chiral selectors for the chiral recognition (separation) are proposed. The model assumes that each individual analyte-CS interaction is fast, fully independent on other interactions and the analyte can interact with CS in 1: 1 ratio and that the analyte is present in the concentration small enough not to considerably change the concentration of free CSs. Under these presumptions, the system behaves as there was only one chiral selector with a certain overall equilibrium constant, overall mobility of an a lyte-se lector complex (associate) and overall rate constant of interconversion in a chiral environment. We give the mathematical equations of the overall parameters. A special interest is devoted to the dynamics of interconversion. Interconversion in systems with mixture of chiral selectors is governed by two apparent rate constants of interconversion in the same way as in case of singe-selector systems. We propose the experimental design that allows to determine rates of interconversion in both chiral and achiral parts of the enantioseparation system separately. The approach is verified experimentally in the second part of the article. (c) 2008 Elsevier B.V. All rights reserved..