Satoshi Fujinaga

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

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.

Separation of Metal Complexes with Counter Ions by Tube Radial Distribution Chromatography Using a Ternary Solvent Containing 8-quinolinol

An open-tubular capillary chromatography system (tube radial distribution chromatography, TRDC) was developed using a ternary solvent (water-acetonitrile-ethyl acetate; volume ratio, 3:8:4) containing 10 mmol L(-1) 8-quinolinol for the separation of nitrate, chloride, and sulfate compounds of Ni(II), Al(III), and Fe(III). When a mixed solution of the Ni(II) compounds was injected into an untreated fused-silica capillary tube (90 cm × 75 μm i.d.) with a ternary solvent flow rate of 0.8 μL min(-1), the compounds were eluted in the following order: [Ni(II)-(8-quinolinol)3] complex, [Ni(II)-(8-quinolinol)]-nitrate ion interaction complex, [Ni(II)-(8-quinolinol)]-chloride ion interaction complex, and [Ni(II)-(8-quinolinol)]-sulfate ion interaction complex. The elution of mixtures of the Al(III) and Fe(III) compounds showed similar trends.

Investigation of the Composition for a Ternary Solvent System in Tube Radial Distribution Chromatography

A tube radial distribution chromatography (TRDC) system was developed based on the tube radial distribution of a ternary solvent system. The composition for the water–hydrophilic organic solvent–hydrophobic organic solvent in TRDC was investigated using phase diagrams, chromatograms, and fluorescence photographs. Mixtures of a hydrophilic organic solvent (acetonitrile, ethanol, methanol, 1-propanol, or 1,4-dioxane) and a hydrophobic solvent (ethyl acetate, hexane, 1-butanol, or chloroform) were examined as the ternary solvent system, which was the carrier solution in TRDC. Water–acetonitrile–chloroform and water–acetonitrile–ethyl acetate systems performed well in TRDC. A model analyte solution of 1-naphthol (NA) and 2,6-naphthalenedisulfonic acid was separated by TRDC using the chloroform solvent system with a range of volume ratios for the solvent components. The elution order of these two compounds could be reversed by changing the solvent system from organic solvent rich to water rich. A mixture of five analytes, NA, Eosin Y, 1-naphthalenesulfonic acid, 2,6-naphthalenedisulfonic acid, and 1,3,6-naphthalenetrisulfonic acid, was also separated using the water–acetonitrile–chloroform solvent system (32:65:3 volume ratio). These compounds eluted in the order given above.