SOME ASPECTS OF ION-EXCHANGE CHROMATOGRAPHY EMPLOYING ADSORBED ION-EXCHANGERS ON REVERSED-PHASE COLUMNS

The nature of the retention of ionic solutes in the presence of alkyl sulphonates and quaternary alkylammonium halides is examined, and it is shown that the ion-exchange reagents adsorbed on the hydrocarbon stationary phase and act as adsorbed ion-exchange agents. Thus, in the system examined the major mechanism of retention is normal ion-exchange chromatography. This paper demonstrates that a layer of solvent exists over the surface of the bonded phase which can be shown by the nature of the adsorption isotherm of methanol on the bonded phase; this is also confirmed chromatographically. In a similar manner, the adsorption isotherm of sodium octane sulphonate is also determined, and the presence of the adsorbed layer of the octane sulphonate confirmed by chromatographic measurements. By the use of conductivity and nuclear magnetic resonance chemical shift measurements, it is shown that in the system examined and under the conditions where solutes are retained by an ion-exchange mechanism on the surface of the stationary phase, both solute and ion-exchange reagent are ionized. © 1979.