Interpretation of Chromatographic Retention Based on Electrostatic Theories

Electrostatic potential is responsible for various phenomena, particularly for the behaviors of ionic species in solution and at various interfaces. In some modes of chromatography, electrostatic interaction often governs overall retention selectivity; ion-exchange chromatography is a typical example. Thus, though the understanding of electrostatic interaction is essential to interpret and predict chromatographic retention in some cases, sufficient attention has not been paid to its roles. There are some possible reasons for this situation: (1) direct estimation of the potential is usually difficult; (2) simple models not involving the contribution from electrostatic potential have given rather good explanations to experimental data. Some research groups have recently attempted to take electrostatic potential effects into consideration in various ways, and have successfully developed chromatographic models. These approaches are expected to facilitate understanding of chromatographic phenomena dominantly controlled by electrostatic interaction and to provide a view of more physical significance. In this review, the author mentions advantages of chromatographic models based on electrostatic theory over usual separated-phase models, and shows problems to be solved.