ESTIMATING DIFFUSION-COEFFICIENTS FOR ALKYLBENZENES AND ALKYLPHENONESIN AQUEOUS MIXTURES WITH ACETONITRILE AND METHANOL

The accuracy of various empirical approximation methods of estimating the diffusion coefficients of alkylbenzenes and alkylphenones in aceto nitrile (ACN)/water and methanol (MeOH)/water solvent systems is repor ted, Diffusion coefficients for these solutes have been measured over a wide range of solvent compositions and temperatures. A novel empiric al modification of the Wilke-Chang method has been developed by correl ating measured values with solute and solvent parameters, The correlat ion, along with the Wilke-Chang and Scheibel correlations, was examine d by comparing the computed diffusion coefficients with the measured v alues, We find that the percent errors of the proposed correlations ar e no greater than 10% for both ACN/water and MeOH/water systems and th at the accuracy of the correlation is 2-3-fold better than those of th e other two correlations. We recommend the use of this correlation wit h the above homologous series of solutes for the evaluation of column performance in reversed-phase liquid chromatography.