Electroosmotically driven thin-layer electrochromatography on silica media

Abstract

Electroosmotic solvent flow has been demonstrated in planar chromatography media. The application of a 800 V cm −1 field along conventional silica thin-layer chromatography plates has been shown to give solvent migration rates of 0.039 and 0.210 cm s −1 with ethanol and acetonitrile, respectively. Electroosmotic elution has been applied to the separation of pirimicarb and a number of related compounds by planar electrochromatography. The elution characteristics of these compounds were similar to those obtained by conventional thin-layer chromatography, yielding the same elution sequence, but more rapidly. Whilst these compounds are separated by using conventional thin-layer chromatography, they require an elution time of ca. 18 min and comparable electrochromatographic separations can be achieved electroosmotically in only 90 s; this corresponds to a 12-fold increase in elution rate. Reduced band-broadening is also evident with the electrochromatographic elution.