Pressurized planar electrochromatography (PPEC) is the mode which offers much higher separation efficiency in comparison to conventional planar chromatography, including both higher performance and much higher speed of separation. In this paper, we present a new device for performing PPEC in which the whole area of the chromatographic plate is pressurized. Both electrodes (anode and cathode) are washed with the mobile phase during the experiment, which prevents gas bubbles from collection in the region of the electrodes. This device enables directly controlling the flow rate of the mobile phase during the electrochromatography process. Mobile phase control offers the possibility of researching the influence of various properties of the PPEC system on separation efficiency. One important relationship to investigate is plate height vs mobile phase flow rate. This relationship helps to choose the optimal value of the mobile phase flow rate during the separation process. Considerable difference in shape of this relationship is demonstrated for conventional planar chromatography plates and high performance planar chromatography plates. Examples of the influence of some properties of the separating system on flow rate of the mobile phase are demonstrated, such as the buffer concentration in the mobile phase, the pH value of the buffer solution of the mobile phase, the type of chromatographic plate, and the voltage applied to the electrodes.

Developments in planar electrochromatography in open (PEC) and closed (PPEC) systems are reviewed. The discussion focuses on progress in chamber construction for planar electrochromatography, separating system performance, equilibration of the PPEC process, separation time and selectivity, and the general advantages, disadvantages and prospects of this separation mode.

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Preliminary results of 2-D separation of test dye mixture using high-performance thin-layer chromatography (HPTLC) and pressurized planar electrochromatography (PPEC) are demonstrated. The advantage of 2-D HPTLC/PPEC separation is based on different separation selectivities obtained in both HPTLC and PPEC systems. HPTLC RP18 W plates of 5x20 cm from Merck were used in the investigations. In the first dimension, a HPTLC process was performed using 5 cm length of the plate and in the second dimension PPEC separation was obtained applying plate of 20 cm length. PPEC process followed prewetting the chromatographic plate with sample zones on it, which were partly separated after first dimensional (HPTLC) separation. In the experiments, the modified version of PPEC device for 20 cm long chromatographic plate and the reservoir for prewetting the adsorbent layer were applied.

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