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 mu m; tube effective length, 100 - 200 cm; and flow rate, 0.2 - 1.5 mu L 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.