Novel stationary phases for open-tubular CEC

In this paper a variety of silica-based, stationary phases for open-tubular CEC are introduced. These include several columns bearing alkyl groups, but also charge-bearing and polar ones. The resulting columns are investigated for the separation of mixtures of uncharged polyaromatic hydrocarbons, of aromatic ketones and alcohols, as well as for the separation of charged biological molecules, namely amino acids. While most of the stationary phases were suited to the separation of the uncharged molecules, only the columns bearing the polar (pentafluorophenyl)dimethyl groups allowed the separation of the amino acids. In the case of the alkyl groups, the separation generally improved with increasing chain length. The effect of the degree of branching on the separation quality depended on the type of analyte. Finally it was noted that the behavior of the stationary phases investigated here under CEC conditions deviates from the customary behavior of such or similar stationary phases in hydrodynamically driven chromatography.