ELECTROOSMOSIS IN CAPILLARY ZONE ELECTROPHORESIS WITH NONUNIFORM ZETA-POTENTIAL

The influence of the longitudinally non-uniform zeta potential on processes in capillary zone electrophoresis was studied. The velocity field of the electroosmotic flow in capillary tubes is modelled by the Navier-Stokes equations. Their stationary solution represents convective transport of a solute which is taken into account in the continuity equation for the concentration distribution. All equations are studied numerically. The results represent the time evolution of initial forms of sample peaks. These are presented in graphical form for several cases of zeta potentials which are either instructive or closely related to situations encountered in practice. It is shown that plug-like flow in the capillary cannot be expected and that a non-uniform zeta potential generally leads to significant dispersion of peaks.