Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10547825 | Journal of Chromatography A | 2011 | 11 Pages |
Abstract
The results of a numerical simulation study of the diffusion and retention in fully porous spheres and cylinders are compared with some of the high order accuracy analytical solutions for the effective diffusion coefficient that have been derived from the effective medium theory (EMT) theory in part I of the present study. A variety of different ordered (spheres and cylinders) and disordered (cylinders) packings arrangements has been considered. The agreement between simulations and theory was always excellent, lying within the (very tight) accuracy limits of the simulations over the full range of retention factor and diffusion constant values that is practically relevant for most LC applications. Subsequently filling up the spheres and cylinders with a central solid core, while keeping the same packing geometry and the same mobile phase (same thermodynamic retention equilibrium), it was found that the core induces an additional obstruction which reduces the effective intra-particle diffusion coefficient exactly with a factor γpart = 2/(2 + Ï3) for spherical particles and γpart = 1/(1 + Ï2) for cylinders (Ï is the ratio of the core to the particle diameter, Ï = dcore/dpart). These expressions hold independently of the packing geometry, the value of the diffusion coefficients and the equilibrium constant or the size of the core. The expressions also imply that, if considering equal mobile phase conditions, the presence of the solid core will never reduce the particle contribution to the B-term band broadening with more than 33% (50% in case of cylindrical pillars).
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Sander Deridder, Gert Desmet,