Extended thermodynamic approach to ion-interaction chromatography for highsurface potential: Use of potential approximation for simplified retentionequations

The chromatographic behaviour of charged analytes in ion interaction chroma tography (IIC) has been investigated theoretically A potential approximatio n for high surface potential was used to obtain simplified retention equati ons that are able to model analyte retention as a function of both the mobi le and stationary phase concentrations of the ion-interaction reagent (IIR) . The main advantage of using this potential approximation is that it allow s calculation of the surface potential, without needing detailed informatio n on physical and chemical properties of the mobile phase. Retention equations of previous thermodynamic retention models can be viewe d as limiting cases of the present theory One of the most reliable data set s concerning the retention behaviour of charged substances in IIC, obtained at high surface potential, was used to test the new retention equations.