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

Abstract

IntroductionAnalytical methods using capillary tubes have attracted a great deal of interest since the last century [1][2][3]. Well-known methods include capillary electrophoresis, capillary electrochromatography, micellar electrokinetic capillary chromatography, and highperformance liquid capillary chromatography using packed and monolithic columns. However, only a few new concepts concerning capillary chromatography have been reported in the last decade [4,5]. 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 AbstractA capillary chromatography called the tube radial distribution chromatography (TRDC) system has been developed using an open capillary tube and a water-hydrophilic/hydrophobic organic solvent mixture carrier solution. In this study, we examined the effects of the analyte injection volume (injection time) and concentration on the chromatograms in the TRDC system using a fused-silica capillary tube (50 µm i.d. and 100 cm effective length) and a water-acetonitrile-ethyl acetate mixture carrier solution (volume ratio, 3: 8: 4). Analyte solutions of 1-naphthol and 2,6-naphthalenedisulfonic acid (1 mM each) were injected into the system with various injection times of 10-1500 s from a height of 20 cm by gravity. They were separated and detected in this order with good reproducibility up to an injection time of 150 s. The analyte solutions (0.075-3.0 mM) were analyzed with the definite injection time of 30 s from a height of 20 cm by gravity. They were separated and detected with a baseline separation and their calibration curves showed linearity up to 1.5 mM. It was confirmed that the TRDC system worked well as a quantitative analysis.

Fundamental Research and Application of the Specific Fluidic Behavior of Mixed Solvents in a Microspace

“…The influence of the tube temperature, tube inner diameter, flow rates, injection volumes, and carrier solvents on the separation performance was detailed in these studies. 25,[42][43][44][45] A mixture of hydrophilic 2,6-naphthalenedisulfonic acid and hydrophobic 1-naphthol was used as a model to examine the elution behavior of the solutes in TRDC. 16,17,25,35 In the organic solvent-rich solution system, 1-naphthol and 2,6-naphthalenedisulfonic acid were eluted in this order, whereas a reverse elution order was obtained in the water-rich solution system (i.e., 2,6-naphthalenedisulfonic acid followed by 1-naphthol).…”

Confirmation of Separation Mechanism Through Visualization of Microfluidic Behavior of Fluorescent Analytes in Tube Radial Distribution Chromatography

“…For the moment, we think that the instability may be caused by unstable flow behavior of the organic solvent-rich minor outer phase on the inner wall of fused-silica capillary tube, although it was improved by using an inert-inner wall fused-silica capillary tube instead of an untreated-wall one. The reproducibility of peak heights and areas for TRDC with the organic solvent-rich solution was reported in the previous paper [13]. These data for TRDC with the water-rich solution will be examined, making technical improvements.…”