Specific microfluidic behavior of ternary mixed carrier solvents of water–acetonitrile–ethyl acetate in open-tubular capillary chromatography and the chromatograms

Abstract

We have developed a capillary chromatography system using an open-tubular capillary tube and a ternary water–hydrophilic–hydrophobic organic mixture carrier solution. We call the system “tube radial distribution chromatography (TRDC) system”. In this study, fluorescence photographs of the dyes dissolved in the ternary mixed carrier solvents in the TRDC were examined under various conditions concerning the inner diameters, tube temperatures, tube effective lengths, and flow rates (or average linear velocities). The TRDC system used an untreated fused-silica capillary tube and a ternary water–acetonitrile–ethyl acetate mixture carrier solution (3 : 8 : 4 volume ratio; the organic solvent-rich solution). The tube radial distribution of the carrier solvents that generated the organic solvent-rich major inner phase and the water rich minor outer phase could be observed in 50–700 μm inner diameters of the tubes at an average linear velocity of 11 cm min⁻¹ through the fluorescence microscope–CCD camera. The model analyte solution of 1-naphthol, 1-naphthalenesulfonic acid, 2,6-naphthalenedisulfonic acid, and 1,3,6-naphthalenetrisulfonic acid was subjected to TRDC. They were separated and detected in this order with 50, 75, and 100 μm inner diameters of the open-tubular capillaries.