Solvent concentration dependence of solute distribution coefficient



A simple method for modeling the solvent concentration dependence of solute distribution coefficient is described. Ideal and modified distribution models are proposed based on the mechanism of multicomponent competitive adsorption and the theory of solvent association. The system cresol-methanol/water-β-CD-silica is tested using the models, which compared with other experimental results show that the ideal distribution model fails at higher water concentrations and that the modified model can describe well the observed solute distribution behavior over the entire concentration range. The relative impact of nonideal factors in the adsorbed phase and the solvent association in the mobile phase on the distribution dependence shows that the limitation of the ideal model at higher water concentrations results mainly from uneven saturation capacities of the solute and solvent components for the system studied here.