Rate constants of mass transfer kinetics in reversed phase liquid chromatography

The parameters of the kinetics of mass transfer of several n-alkylbenzenes were measured by the method of moments on a series of columns prepared with different samples of the same RPLC packing material having widely different average particle diameters, from 3 to 50 mu m. These data were analyzed using the available models, and correlations. The best agreement between experimental and theoretical data was obtained under the assumption that the rate constant for the external mass transfer increases with increasing average particle size, an unexpected conclusion. It was also shown that the interpretation of the relative importance of the roles of pore diffusivity and surface diffusivity in the internal mass transfer kinetics is somewhat ambiguous and that the conclusion to be drawn from experimental results depends on the assumptions made regarding and the average particle regarding the tortuosity model and the relationship between k(ext) size. (c) 2005 American Institute of Chemical Engineers.