Planar electrochromatography

Nurok, D. Koers, J.M. Carmichael, A. Role of buffer concentration and apphed voltage in obtaining a good separation in planar electrochromatography. J. Chromatogr., A 2003, 983, 247-253. 

For the separation of baizoic acids, planar electrochromatography was used. In this approach, an electro-osmotic flow is used to drive the mobile phase in TLC. Planar electrochromatography has several advantages over classical TLC, especially substantially faster separation. For example, separation by planar electrochromatography can be 10 times faster than that using ordinary TLC. 

Monolithic columns, formed from the co-polymerization of divinylbenzene and vinylbenzyl chloride or styrene, were observed to be resistant to bubble formation.11 Application of pressure in electrochromatography, discussed below, also reduces bubble formation. A massively parallel detector capable of scanning up to 1000 capillaries using planar confocal fluorescence has been used for DNA sequencing.1213 Recovery of fluorescence following pho-tobleaching has been used to measure DNA mobility in agarose gel.14... 

An optimum of flow profile has recently been achieved for capillary electrophoresis [76], when the mobile phase migration is done by electroosmosis. It is the situation that has been utilised for electrochromatography. For planar chromatography, the optimum of the linear flow velocity is approximated when the convex shape of a forced-flow profile chiefly counterbalances the concave profile of the advancing meniscus, it is possible to reach optimal efficiency as a function of linear flow velocity [67]. This is demonstrated in Fig. 10.6. At the optimum of efficiency, the microflow profile is nearly linear as the convex and concave forms of laminar flow and the concave form of the advancing meniscus counterbalance each other (Fig. 10.7). 

Currently, most planar chromatography is based on the thin-layer technique, which is faster, has better resolution, and is more sensitive than its paper counterpart. This section is devoted to thin-layer methods. Capillary electrochromatography is described in Section 33D. 

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