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 Chroma tography (IIC) was theoretically investigated. Simplified retention equations were obtained via the linearized potential e xpression. They can be used to model analyte retention as a function of bot h the mobile and stationary phase concentration of the Ion-Interaction reag ent (IIR), if the surface potential is below 25 mV. Simplified retention equations were compared to those, which can be obtaine d from two of the most important retention models in IIC. They reduce to st oichiometric or electrostatic retention model equations if the surface pote ntial or pairing equilibria are respectively neglected.