This type of electrophoresis is carried out in a closed medium with critical observations made by focusing and adjusting the lens of the microscope.
Complexity of this method is associated with electro-osmosis generated by electric field influence on the double layers of the sample cell walls.
In the usually used closed cells, this creates Poiseuille type back flow, leading to parabolic velocity profile.
It is possible to focus microscope on these stationary layers and observe particle motion that is not affected by electro-osmosis.
Details of this method are presented in IUPAC Technical Report[1] prepared by a group of most known world experts on the electrokinetic phenomena.