An apparatus for pressurized planar electrochromatography consists of two parts: a separation chamber and a high voltage power supply, Fig. 12. The sample is applied to a prewet layer as spots of bands and quickly mounted in a holder in the over-pressured separation chamber. The sorbent layer is covered with a plastic foil and ceramic sheet, which are pressed onto the sorbent layer using a hydraulic press. Liquid is circulated through channels in the metal block holding the layer to control temperature. Opposite edges of the layer are placed in contact with the buffer solution containing the polarizing electrodes (or alternatively the electrodes are pressed against the layer and the buffer solution is wicked from the reservoirs to the layer). A polarizing voltage applied between the two electrodes generates the electroosmotic flow of mobile phase through the layer.