Naoya Jinno

Introduction of fluorescence and chemiluminescence detection to capillary chromatography based on tube radial distribution of water–hydrophilic–hydrophobic organic mixture carrier solvents

Fluorescence and chemiluminescence detection were introduced into a tube radial distribution chromatography (TRDC) system using an open fused-silica capillary tube and a water–acetonitrile–ethyl acetate mixture carrier solution. Model analyte mixture solutions, such as Eosin Y and perylene as well as dansyl methionine and perylene, were injected into the capillary tube by a gravity method. The analyte solution was subsequently delivered through the capillary tube with the carrier solution by a microsyringe pump; the system worked under laminar flow conditions. The analytes were separated through the tube and detected by on-capillary with fluorescence detection or by end-capillary with chemiluminescence detection taking advantage of peroxyoxalate chemiluminescence reaction. Eosin Y and perylene as well as dansyl methionine and perylene were detected in this order with a carrier solution of water–acetonitrile–ethyl acetate (15 : 3 : 2 volume ratio), while they were detected in the reverse order with a carrier solution of water–acetonitrile–ethyl acetate (3 : 8 : 4 or 2 : 7 : 4 volume ratio) with fluorescence or chemiluminescence detection. The elution times of the analytes were reversed by changing the component ratio of the solvents in the carrier solution. A fluorescein isothiocyanate-labeled bovine serum albumin was also analyzed and separated from the coexisting labeling reagent with the present system.

Separation of dansyl-DL-amino acids by open tubular capillary chromatography based on tube radial distribution phenomenon of the ternary mixed carrier solvents

Separation of enantiomers, dansyl-DL-amino acids, was carried out by open-tubular capillary chromatography based on the tube radial distribution of the carrier solvents. An untreated poly(tetrafluoroethylene) capillary tube (100 μm inner diameter and 90 cm effective length) as a separation column and a water–acetonitrile–ethyl acetate mixture containing cyclodextrin as a carrier solution were used in the chromatography. An analyte solution of dansyl-DL-amino acids, such as dansyl-DL-methionine, was injected into the capillary tube by a gravity method. The analyte solution was subsequently delivered through the capillary tube with the carrier solution by a microsyringe pump. The ternary mixed carrier solution (water-rich carrier solution) was radially distributed in the capillary tube based on the tube radial distribution phenomenon, causing the formation of inner (water-rich) and outer (organic solvent-rich) phases. The outer or capillary wall phase acted as a pseudo-stationary phase in the chromatography. The analytes were separated through the capillary tube with on-capillary detection by an absorption or a fluorescence detector. The D-enantiomer and the L-enantiomer were eluted in this order with a baseline separation. The separation mechanism of the enantiomers in the open-tubular capillary using cyclodextrin was discussed.

Capillary chromatography based on tube radial distribution of aqueous‐organic mixture carrier solvents: Introduction of inner‐wall‐modified capillary tubes

We developed a novel capillary chromatography using an open capillary tube and a water-hydrophilic/hydrophobic organic solvent mixture as a carrier solution. The capillary chromatography was called a tube radial distribution chromatography (TRDC) system. In this study we tried to introduce inner-wall-modified (e.g. phenylboronic-acid- and iminodiacetic-acid-modified) fused-silica capillary tubes to the TRDC system to separate model mixture analytes. The phenylboronic-acid-modified capillary tube was combined with absorption detection to analyze a mixture of adenosine and deoxyadenosine. The iminodiacetic-acid-modified capillary tube was combined with chemiluminescence detection using a luminol reaction to analyze a mixture of copper(II) and hematin. A water (carbonate buffer)/ACN/ethyl acetate (2:7:4 v/v/v) and a water (carbonate buffer)/ACN/ethyl acetate (15:3:2 v/v/v) mixture solution were used as carrier solutions in the TRDC system, and typical carbonate buffer solutions not containing any organic solvents were also used as carrier solutions as reference solutions. In both modified capillary tubes, the organic-solvent-rich carrier solution successfully improved the separation of the mixture analytes in the system, and the water-rich carrier solution greatly depressed their separation, when compared with chromatography using carbonate buffer carrier solutions containing no organic solvents. Such observed phenomena were discussed considering the separation mechanism of the TRDC system.

Tentative Comparison of Tube Radial Distribution Chromatography and CZE

Tube radical distribution chromatography (TRDC) uses an untreated open tubular capillary tube and a ternary mixture of solvents (water and hydrophilic/hydrophobic organic solvents) as a carrier solution. A model analyte mixture comprising 1-naphthol, 1-naphthoic acid, 1-naphthalenesulfonic acid, 2,6-naphthalenedisulfonic acid, and 1,3,6-naphthalenetrisulfonic acid was examined by the TRDC and capillary zone electrophoresis (CZE) systems that comprised mainly a capillary tube and a detector. In the TRDC system the elution order of analytes could be changed by altering the component ratios of the solvents, whereas in the CZE system the elution order was changed by altering the electroosmotic flow direction. The experimental data obtained provide clues about the features and utility of TRDC as a new separation method.

STUDY OF OUTER PHASES IN CAPILLARY CHROMATOGRAPHY BASED ON TUBE RADIAL DISTRIBUTION OF CARRIER SOLVENTS UNDER LAMINAR FLOW CONDITIONS

A capillary chromatography system that consists of an open capillary tube composed of fused–silica, polyethylene, and poly(tetrafluoroethylene), and a water–hydrophilic/hydrophobic organic mixture carrier solution has been developed. We call this system the tube radial distribution chromatography (TRDC) system. In this study, variance, theoretical plate number, and height equivalent to a theoretical plate for a solute peak in the chromatogram were expressed using theoretical equations derived from the differential equation for the secondary moment of a solute. The relationship between the thickness and diffusion coefficient in the outer phase in the capillary tube in the TRDC system was calculated from theoretical equations using numerical values for the analytical conditions and experimental data. The outer phase that featured the TRDC system had a larger diffusion coefficient and a larger thickness than those of the stationary phase in standard liquid chromatography. We confirmed the separation performance obtained on the basis of the tube radial distribution of the carrier solvents under laminar flow conditions in the TRDC system by considering the inner and outer phase generation in the capillary tube.

Tube radial distribution phenomenon observed in an aqueous micellar solution of non-ionic surfactant fed into a microspace and an attempt of capillary chromatographic application

A new type of tube radial distribution phenomenon was observed in an aqueous micellar solution of non-ionic surfactant that was fed into a microspace. A homogeneous aqueous solution containing 2 wt % Triton X-100 and 2.0 M sodium chloride was fed into a microchannel (40 μm in depth and 200 μm in width) in a microchip at a flow rate of 4.0 μL/min, where the microchip was maintained at a temperature of 34°C. The homogeneous aqueous solution changed to a heterogeneous solution with two phases in the microchannel; the surfactant-rich phase was generated around the middle of the channel, while the aqueous phase containing little surfactant was formed near the wall. The radial distribution of the surfactant was observed through Rhodamine B dissolved in the aqueous micellar solution with a bright-field microscope — CCD camera system. An open-tubular capillary chromatographic system was also tried to develop using the fusedsilica capillary tube (75 μm inner diameter and 120 cm length) as a separation column and the aqueous micellar solution as a carrier.