The role played by the hydrodynamics of a system targeted for separation of species under the potential healthy role of an orthogonal electrical field has been studied from a fundamental point if view by using geometrical scaling in micro-capillaries of rectangular geometry. The potential implications of capillary electrophoresis are analyzed in this contribution by using a cylindrical capillary with an orthogonal electrical field. This can be achieved experimentally in the lab by using a wire-cylindrical electrode type of configuration. This leads to an “annular-type” of configuration. Therefore, This contribution focuses on extending the previous analysis to an annular capillary system where the radial electrical field effect is considered to be equivalent to that of the orthogonal field in rectangular geometry. The explicit analytical expressions derived for the effective parameters as a function of the applied electric field, capillary porosity and the flow regime are the bases for computing, in each case, the time of separation parameter. The optimal values of time of separation are compared to determine which geometry and under what type of condition favor the most the separation of two hypothetical species. The result of the analysis can be used in the design of separation devices as well as environmental applications such as soil remediation and wastewater treatment. Illustrations of how a secondary electrical field can aid in reducing the optimal separation/treatment time are included and directions for further research are presented.