Extended thermodynamic approach to ion interaction chromatography for low surface potential: use of the linearized potential expression

The chromatographic behaviour of charged analytes in Ion Interaction Chromatography (IIC) was theoretically investigated. Simplified retention equations were obtained via the linearized potential expression. They can be used to model analyte retention as a function of both the mobile and stationary phase concentration of the Ion-Interaction reagent (IIR), if the surface potential is below 25 mV. Simplified retention equations were compared to those, which can be obtained from two of the most important retention models in IIC. They reduce to stoichiometric or electrostatic retention model equations if the surface potential or pairing equilibria are respectively neglected.