Layer dielectrochromatography—under external alternating current, LDEC

During the layer chromatographic process the sample is separated into fractions. Drawn by capillary forces, the developing solvent (mobile-phase) migrates through the thin layer (stationary phase) over a distance defined by the solvent front that is inversely related to the solvent flow velocity. Considering that the physical properties of the dielectric liquids are influenced by the electric fields and the capillary tubes can be used to simulate and to understand the solvent displacement through porous media, we obtained interesting results by applying transversal alternating electric fields over them. These electric fields, applied in equi- or counter-current arrangement, can influence the solvent front velocity and the solute migration distance, generating two phenomena, dielectroosmotic flow and dielectrophoresis, which applied to the classical thin-layer chromatography are the basis of the layer dielectrochromatography (LDEC). To investigate LDEC principles, a horizontal and a vertical LDEC chamber were conceived, handmade and used for tests with lipophilic and hydrophilic dyes. To obtain electric fields of different geometries, five armatures of different shapes were created and investigated. Porous media with a high dielectric constant with alumina and barium titanate were prepared and tested.