Evaporation-induced solvent migration in electrically-driven thin layer chromatography

When high potential electric fields are applied to thin layer chromatography media solvent migration is observed that in early work was assigned to electroosmosis. Whilst these early experiments can be reproduced using modern chromatographic media, this migration has been shown to be independent of the field direction, and cannot therefore be electroosmotic in origin. This migration has been shown to be dominated by solvent evaporation resulting from Joule heating and coronal discharge, which is concentrated in a restricted region of the chromatographic plate. Similar migration rates can be achieved in the absence of the electric field by the application of localised heating. Localised heat application is discussed as a possible means of inducing solvent migration in planar chromatography. (C) 1999 Elsevier Science B.V. All rights reserved.