A new open-tubular approach to capillary electrochromatography.

While most capillary electrochromatography is based on the use of packing materials similar to those for HPLC, this method creates a new surface on the inner wall of the fused-silica tubing that is then modified with various organic moieties. In this format there is no need for frits, and bubble formation is not a serious problem. With 50-microns-i.d. capillaries, molecules are separated by a combination of differences in electrophoretic mobility and solute/bonded phase interactions. A number of examples are presented, which include tetracyclines, peptides, and proteins. Peaks for all compounds, even basic ones, exhibit both good efficiency and symmetry. The reproducibility of migration times is excellent even after extended use of the column.