Broadband Cavity Enhanced Absorption Spectroscopy as a Detector for HPLC

Abstract

The first demonstration of a cavity enhanced absorption spectroscopy (CEAS) based technique, applied to HPLC detection is reported. Broadband cavity enhanced absorption spectroscopy (BBCEAS) has been used for detection in a HPLC system (HPLC-BBCEAS). Measurements were made on the dyes rhodamine 6G and rhodamine B between 450 and 600 nm. The sensitivity of the measurements as determined by the minimum detectable change in the absorption coefficient, alpha(min), were 2.9 x 10(-5) cm(-1) at 527 nm and 1.9 x 10(-5) cm(-1) at 556 nm, the peak absorption wavelengths of rhodamine 6G and rhodamine B, respectively. The limits of detection (LOD) for the two dyes were 426 and 271 pM, respectively. The LOD of the HPLC-BBCEAS setup was found to be between 54 and 77 times lower than with a Perkin-Elmer HPLC (series 200) comprising a 200EP photodiode array detector. The sensitivity of the developed setup also compared favorably with the previous single wavelength HPLC-CRDS studies while using a considerably lower cost experimental setup and simpler experimental methodology. The use of BBCEAS detection also allowed the discrimination following an isocratic HPLC separation of the nearly co-eluting dyes rhodamine 6G and rhodamine B.

Trace species detection in the near infrared using Fourier transform broadband cavity enhanced absorption spectroscopy: initial studies on potential breath analytes

“…There are clear advantages in having this capability: to measure several compounds simultaneously and to increase the amount of information in a particular measurement, thereby statistically enhancing the output (for example, in measuring several spectral lines to record an isotopic ratio); and to improve specificity, where target species exhibit relatively broad spectral signatures. Several schemes have been reported for BB-CEAS involving different sources and detection apparatus, and including application to the measurement of liquid and/or surface borne species [10,13,14,15,18,19]. On the whole, these studies have been at visible wavelengths, and as broad band optical sources both light emitting diodes and discharge lamps have featured predominantly and have been used with either imaging spectrometers or Fourier transform interferometers as detection systems.…”

Near-infrared broad-band cavity enhanced absorption spectroscopy using a superluminescent light emitting diode

“…those techniques that utilise broad-band emission sources, are increasing in popularity where it is desirable either to measure several compounds simultaneously that absorb in different spectral regions or where specificity is required for target species with extended absorption features (such as relatively large molecules or surface/liquid-borne species). Several studies have been reported that combine different broad-band sources such as arc-lamps [1][2][3][4][5][6] and light emitting diodes (LEDs) [7][8][9][10][11][12] with dispersive and interferometric detection schemes to detect gas phase species such as iodine oxides, 5 NO x compounds, 7,8,10,11 and solutions containing dyes (e.g. coumarin 334, brilliant blue-R, and rhodamine B and 6G) 9,12,13 which absorb at visible wavelengths.…”

“…Several studies have been reported that combine different broad-band sources such as arc-lamps [1][2][3][4][5][6] and light emitting diodes (LEDs) [7][8][9][10][11][12] with dispersive and interferometric detection schemes to detect gas phase species such as iodine oxides, 5 NO x compounds, 7,8,10,11 and solutions containing dyes (e.g. coumarin 334, brilliant blue-R, and rhodamine B and 6G) 9,12,13 which absorb at visible wavelengths. High power supercontinuum sources have also been demonstrated in cavity enhanced spectroscopy, 14,15 but these are devices that represent a major financial investment, generate a wide spectral output, usually much larger than the stop band of the high reflectivity cavity mirrors, and generally have optimised performance in the visible and near-IR (<1 mm).…”

Cavity-enhanced absorption using an atomic line source: application to deep-UV measurements

“…25 The estimated limit of detection for acetone is higher than the range found in healthy breath (390 to 850 ppbv), but further improvements in sensitivity could make this approach practical for breath analysis. Other applications include detectors for chromatography, for which both CRDS 26,27 and CEAS 28 have previously been proposed. Although this work has focussed on gases, the approach is also feasible for liquid samples.…”