Polymer–water partition coefficients of extended range measured by using organic modifiers in the aqueous phase

A procedure for estimating equilibrium polymer–water partition coefficients over a broad range of solute hydrophobicity is presented and evaluated. The coefficients were calculated from the concentration change in the liquid phase and hydro-organic mixtures of varying proportions were used to extend the range. Three hydrophobic polymers (PP, PE, and EBA), two types of solvent (acetonitrile and alcohols) and 12 model solutes were used. The estimated polymer–water partition coefficients, log Kpw, ranged from −0.5 to 8.5. The coefficients correlated to other partitioning systems such as the calculated log Poctanol–water up to ∼14 and the retention factor (log kw) in reversed-phase liquid chromatography.