General model for the achiral chromatography of enantiomers forming dimers: application to binaphthol

Abstract

This works deals with the development of a model for the description of the chromatographic behavior of enantiomers forming dimers on achiral stationary phases. The model describes the formation of both homochiral and heterochiral dimers by introducing two equilibrium constants, K homo and K hetero, which have to be independently estimated. The adsorption of both monomeric and dimeric species is described by a bi-Langmuir isotherm. Both adsorption and dimerization equilibrium models are implemented in a standard equilibrium-dispersive model of the chromatographic column. The isotherm parameters are determined by fitting of pulses constituted either of the pure enantiomers or of non racemic mixtures of both enantiomers. The validity of the model is then assessed by application to the binaphthol case.