Analytical conditions and separation performance of capillary chromatography based on the tube radial distribution of aqueous-organic mixture carrier solvents under laminar-flow conditions.

We have developed a capillary chromatography system using an open capillary tube made of fused-silica, polyethylene, or poly(tetrafluoroethylene), and a water-hydrophilic-hydrophobic organic mixture carrier solution. This tube radial distribution chromatography (TRDC) system works under laminar-flow conditions. In this study, the following analytical conditions in the TRDC system using a fused-silica capillary tube and a water-acetonitrile-ethyl acetate mixture carrier solution were for the first time examined: tube temperature, 5-25 degrees C; tube inner diameter, 50-250 microm; tube effective length, 100-200 cm; and flow rate, 0.2-1.5 microL min(-1). For example, the effects of temperature on the separation performance in the TRDC system were observed with an organic solvent-rich carrier solution; 1-naphthol and 2,6-naphthalenedisulfonic acid in a model mixture were eluted with baseline separation over the temperature range of 5-23 degrees C. The resolution, theoretical plate number, and height equivalent to the theoretical plate were calculated from the experimental data obtained by examining the effects of the tube length. A mixture of 1-naphthol, Eosin Y, 1-naphthalenesulfonic acid, 2,6-naphthalenedisulfonic acid, and 1,3,6-naphthalenetrisulfonic acid was subjected to the present TRDC system, and the analytes in the mixture solution were eluted in this order with the organic solvent-rich carrier solution, providing good separation performance on the chromatogram.