Application of an HPLC-FTIR Modified Thermospray Interface for Analysis of Dye Samples

Abstract

Previously, we developed a reversed-phase HPLC method compatible to high performance liquid chromatography diffuse reflectance Fourier-transform infrared (HPLC-FTIR) thermospray interface for the analysis of dyes. Dye separation achieved with a mixed-mode (SCX-ODS) column using a small gradient (90 to 80% water with acetic acid) and pH 3.25; 10 to 20% acetonitrile was considered to be suitable for HPLC-FTIR. A constant-voltage setting for the thermospray temperature (227˚C) was successfully used for this gradient condition. The HPLC-separated components deposited as a series of concentrated spots on a moving tape were scanned by specially developed HPLC-FTIR software. Excellent repeatability of the thermospray deposition FTIR chromatograms and IR spectra was obtained. The interface-derived spectra of the separated components of formulated and purified reactive dyes were compared and differences in spectral features were observed.

Enhanced Desolvation and Improved Deposition Efficiency by Modified Thermospray for the Coupling of HPLC and FT-IR

“…Detailed descriptions of the interface have been given elsewhere. [15][16][17][18] The column effluents were transferred to the thermospray interface assembly, which was surrounded by a heated nitrogen gas stream supplied by two channels at 5 l min -1 from each channel, which continually flowed down to the thermospray capillary tubing (125 µm i.d. × 1.5 mm o.d.)…”

“…[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] A thermospray temperature of as high as 280˚C was adequate to completely evaporate pure water at 0.5 ml min -1 , and the thermal degradation of glycine was reported.…”

“…The success or failure of the technique almost exclusively depends on the interface performance. In general, flow cells [1][2][3] and solvent elimination [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] procedures have been used for the interfacing of HPLC to FTIR. Although more convenient, the usefulness of the flow-cell procedure is limited because the aqueous-based mobile phase, commonly used in reversed phase (RP)-HPLC, strongly absorbs IR radiation in many areas of the IR spectrum, resulting in a loss of sample spectral information.…”

“…15 This hyphenated technique was recently employed to analyze linear alkylbenzene sulfonates 16 and reactive dyes. 17,18 Although the use of a heated gas flow at a rate of 6 l min -1 reduced the thermospray temperature, 15 deposition problems, thermospray capillary blockage, a loss of resolution in FTIR chromatograms, [15][16][17] and peak splitting 18 were experienced. To keep these problems in mind, we further revised, or developed, glass thermospray by introducing another heated gas flow channel and a heating plate underneath the deposition belt to enhance the eluent evaporation and to improve the resolution in the FTIR detection chromatograms, respectively.…”

Use of CuO Particles as an Interface in LC-FTIR Analysis

“…Then, the mobile phase is allowed to completely evaporate so that the FTIR spectra of the pure separated substances deposited on the interface can be recorded. [16][17][18][19][20][21][22][23][24][25] Off-line hyphenation exhibits an advantage in that the interference from the mobile phase is completely eliminated, which in turn, improves the signal-to-noise ratio of the resultant FTIR spectra. Gagel et al have utilized the highly IR reflective surface of metals, such as aluminum, as the interface for collecting separated substances from the eluate, followed by recording the corresponding FTIR spectra in the reflection mode.…”