  The zonal electrophoresis in the channels of complex forms is considered
mathematically with the use of computations. We show that for plane S-type
rectangular channels stagnation regions can appear that cause the strong
variations of the spatial distribution of an admixture. Besides, the shape of
an admixture zone is strongly influenced by the effects of electromigration and
by a convective mixing. Taking into account the zone spreading caused by
electromigration, the influence of vertex points of cannel walls, and
convection would explain the results of electrophoretic experiments, which are
difficult to understand otherwise.
