FUNCTIONAL-GROUP BEHAVIOR IN ION-PAIR REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY USING SURFACE-ACTIVE PAIRING IONS

The behaviour of functional groups having widely differing physico-chemical character has been examined in ion-pair reversed-phase high-performance liquid chromatography using surface active pairing ions. The effects of temperature, mobile phase, organic modifier type and percent composition, stationary phase carbon loading and type, ionic strength, and pairing ion structure, charge and concentration on extra-thermodynamic functional group contribution values, have all been determined. Analysis of group behaviour within the framework provided by solvophobic theory is often found to be possible using linear free-energy relationship appraoches, and it is shown that retention behaviour can be described as ion-pair formation in the mobile phase followed by distribution to the stationary phase. In addition, substituent behaviour is found to exhibit linear enthalpy-entropy compensation behaviour, suggesting further that a common retention mechanism can be described for all ionized solutes using these pairing ions. © 1979.