Moving beyond traditional UV-visible absorption detection: cavity ring-down spectroscopy for HPLC

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Chromatography

Background:

• High-performance liquid chromatography (HPLC) is a cornerstone of chemical analysis.
• Existing UV-visible detectors have limitations in sensitivity and noise levels.
• Cavity ring-down spectroscopy (CRDS) offers potential for enhanced detection sensitivity.

Purpose of the Study:

• To develop and demonstrate liquid-phase continuous-wave cavity ring-down spectroscopy (CW-CRDS) for HPLC detection.
• To compare the performance of CW-CRDS with conventional UV-visible detectors.
• To achieve a significant improvement in detection sensitivity and noise reduction for HPLC separations.

Main Methods:

• Utilized a compact doubled-diode single-mode continuous-wave laser at 488 nm.
• Employed a Brewster's-angle flow cell for liquid sample interfacing.
• Measured ring-down time constants in a 0.3-mm path length cell with liquid samples.

Main Results:

• Achieved ring-down time constants up to 5.8 microseconds with liquid samples.
• Demonstrated a baseline noise level of 2 x 10(-7) absorbance units (AU) peak-to-peak during HPLC separation.
• Showcased a detection improvement factor of up to 50 compared to commercial UV-visible detectors.

Conclusions:

• Continuous-wave cavity ring-down spectroscopy is a highly effective method for HPLC detection.
• This CW-CRDS system significantly outperforms conventional UV-visible detectors in sensitivity and noise.
• The technique offers a promising advancement for sensitive and accurate chemical analysis in liquid chromatography.