Electrochromatographic studies of etched capillaries modified with a cyano pentoxy biphenyl liquid crystal

A liquid crystal stationary phase for open tubular capillary electrochromatograpy (OTCEC) is fabricated by etching a fused silica tube and then bonding 4,4′-cyanopentoxy biphenyl by a silanization/hydrosilation process. The versatility of this electrophoretic capillary is demonstrated by separations of proteins, peptides, basic pharmaceuticals and the metabolites of tryptophan. Chromatographic interactions are verified by resolution of two neutral peptides. Variable temperature studies are used to understand the liquid crystal properties of the bonded moiety. EOF measurements as a function of pH and temperature further characterize this unique separation media.