Effects on Gas Chromatographic Peaks of Electric Fields Applied Across Cholesteric Liquid Crystal Stationary Phases

摘要

Earlier studies have shown that a static electric field across a capillary column increased the apparent capacity ratio (measured from the peak maximum) of a liquid crystal stationary phase and produced a more nearly Gaussian-shaped peak plus a small step on the front of the peak. The present study has qualitatively confirmed those effects using cholesteryl laurate, cholesteryl 10-undecenoate, and cholesteryl benzoate and suggests that they may be found for all cholesteric liquid phases. In addition, the peak-fronting phenomenon was found to be a function of both the carrier gas and the applied column potential. Fragmentation of the solute and/or the stationary phase by carrier gas molecules in metastable excited states is proposed to explain the fronting phenomenon. Hysteresis effects have also been observed, indicating that the liquid crystals may take hours to return to their original orientations after imposition or removal of an electric field. (ERA citation 03:007167)