Distribution of Fluorescent Dyes Dissolved in Ternary Mixed Solvent in a Microchannel under Laminar Flow Conditions

Abstract

We observed chromatographic separation in an open capillary tube with a water–hydrophilic–hydrophobic organic mixture carrier solution. The separation is thought to be based on the tube radial distrubution of aqueous and organic carrier solvents in the capillary tube. In this study, in order to obtain information concerning the solvent distribution, we delivered a carrier solution containing fluorescent dyes into a microchannel (100 µm in width × 40 µm in depth) and monitored the tube radial distribution of the dyes using a fluorescence microscope. When an organic solvent-rich carrier solution (water–acetonitrile–ethyl acetate; 3:8:4 volume ratio) containing perylene and Eosin Y was fed into the channel, perylene and Eosin Y were distributed around the center and near the inner wall of the microchannel, respectively. This observation consists with the specific solvent distribution proposed for the chromatography system.

Experimental Consideration of Capillary Chromatography Based on Tube Radial Distribution of Ternary Mixture Carrier Solvents under Laminar Flow Conditions

“…[16][17][18][19][20][21][22][23] Here, instead of acetonitrile (hydrophilic organic solvent), methanol, ethanol, 1,4-dioxane, and 1-propanol were used to prepare the homogeneous ternary mixed carrier solutions that had the specific component ratios of the solvents near the homogeneous-heterogeneous solution boundary region. The component ratios of the solvents in thus prepared carrier solutions were as follows: water-methanol-ethyl acetate (100:20:15 volume ratio), water-ethanol-ethyl acetate (100:20:15 volume ratio), water-1,4-dioxane-ethyl acetate (100:5:10 volume ratio), and water-1-propanol-ethyl acetate (100:10:11 volume ratio).…”

“…Here, instead of ethyl acetate (hydrophobic organic solvent) in the ternary mixture carrier solution of water-acetonitrile-ethyl acetate as in our previous reports, [16][17][18][19][20][21][22][23] chloroform, hexane, and 1-butanol were used to prepare the homogeneous ternary mixed carrier solutions that had the specific component ratios of the solvents near the homogeneous-heterogeneous solution boundary region. The component ratios of the carrier solutions were as follows: water-acetonitrile-hexane (100:30:1 volume ratio), water-acetonitrile-chloroform (100:30:1 volume ratio), and water-acetonitrile-1-butanol (100:15:20 volume ratio).…”

“…19 A carrier solution containing fluorescent dyes was delivered into a micro-channel (100 μm width by 40 μm depth) and the tube radial distribution of the dyes was monitored using a fluorescence microscope. For example, when an organic solvent-rich carrier solution (water-acetonitrile-ethyl acetate; 3:8:4 volume ratio) containing perylene and Eosin Y was fed into the channel, perylene (hydrophobic) and Eosin Y (comparatively hydrophilic) were distributed around the center and near the inner wall of the micro-channel, respectively.…”

Analytical Conditions and Separation Performance of Capillary Chromatography Based on the Tube Radial Distribution of Aqueous-Organic Mixture Carrier Solvents under Laminar-Flow Conditions

“…1) is also drawn based on data of the fluorescence photographs and profiles obtained by a fluorescence microscope-CCD camera. 34 Since our investigation of the TRDC system has just begun, it is important to examine the elution behavior under various analytical conditions in the system in order to expand our knowledge regarding its separation performance. In this study, we examined the analytical conditions of the TRDC system in detail, including tube temperature, tube inner diameter, tube length, and flow rate using fused-silica capillary tubes and a water-acetonitrile-ethyl acetate mixture as a carrier solution.…”

Influences of Analyte Injection Volumes and Concentrations on Capillary Chromatography Based on Tube Radial Distribution of Carrier Solvents under Laminar Flow Conditions

“…Related research has been discussed in detail in our previous papers [6,7]. We have developed a capillary chromatography system using an open capillary tube and a water-hydrophilic/hydrophobic organic mixture carrier solution [6][7][8][9][10][11]. This system works …”