Electrical double-layer models of ion-modified (ion-pair) reversed-phase liquid chromatography

Stoichiometric models of ion-modified reversed-phase liquid chromatography are based on chemical equilibria between ionic modifiers and analyte. These are briefly discussed. Non-stoichiometric models portray the ionic solute as being under the summed influence of all of the ions in the system. Chromatographic theories have been developed that are based on the Poisson-Boltzmann equation, which quantitates the summed influence of the ions in the system on the solute. These ideas and quantitative predictions are described and are critically discussed.