Stochastic theory of multiple-site linear adsorption chromatography

The problem of multiple-site adsorption chromatography is connected with a great number of questions of both chromatographic nature (e.g., the effects of surface heterogeneity on the column efficiency and on the peak shape parameters) and physical chemical relevance (eg., the study of residence time in one sorption step on heterogeneous surfaces). In this study, the multiple-site adsorption, under linear conditions, is considered by using the molecular dynamic theory of chromatography. The probabilistic description is made by means of the characteristic function method and the solution is obtained under the most general conditions of surface heterogeneity. Different cases of surface energy distribution are considered. Relevant chromatographic attributes and the peak shape parameters-skew and excess-are investigated for heterogeneous stationary-phase surfaces. The chromatograms show that slow kinetics and surface heterogeneity have momentous impact on peak tailing. The equivalence of the stochastic model and the lumped kinetic model is demonstrated.