A THERMODYNAMIC AND FLUOROMETRIC INVESTIGATION OF MICELLE CHROMATOGRAPHY - EFFECT OF TEMPERATURE, MICELLE CONCENTRATION AND POLARITY OF SOLUTES

To understand the retention mechanisms involved in reversed-phase micelle chromatography, two models were examined to study the temperature and micelle concentration contribution to the retention process. The first model described the temperature contribution, using the van's Hoff equation, for each of the three equilibria: micelle-to-extra-micelle-mobile-phase, extra-micellar-mobile-phase-to-stationary phase and micelle-to-stationary phase. The second model described the temperature contribution on k' irrespective of the various equilibria involved. It was found that the enthalpy of retention obtained with the second model decreased with increasing micelle concentration. This contradicted a primary assumption in the first model that the equilibrium constants were independent of micelle concentration. No relationship was found between the enthalpy of retention evaluated with either model and the polarity of the partitioned solute molecules. A correlation was found between the entropy of retention and the polarity of these molecules. Fluorescence studies indicated that the micelle solvated molecules were probably located in the core of the micelles which contained other mobile phase components such as 1-propanol and water.