dipole approach in the lon-interaction chromatography of zwitterions— Use of a potential approximation to obtain a simplified retention equation

In ion-interaction chromatography (IIC) the zwitterionic analyte is believed to interact with the stationary phase potential as a result of its electrical dipole, and to compete with the ion-interaction reagent (IIR) for available inner layer sites. The most reliable set of literature data relating to the retention behavior of zwitterions in IIC has been used for successful testing of a high surface-potential approximation which enables the fitting of retention data without detailed information about the physical and chemical properties of the mobile phase. This approach can explain quantitatively, very simply, the retention behavior of zwitterions in IIC.