Optical photothermal detection in HPLC.

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Chromatography

Background:

• Traditional detectors in HPLC and ion chromatography often lack sufficient sensitivity.
• Photothermal detection methods offer potential for improved analytical performance.

Purpose of the Study:

• To optimize a mode-mismatched parallel dual-beam thermal lens spectrometer for HPLC applications.
• To evaluate thermal lens detection with various post-column reagents in ion chromatography.
• To develop and assess a combined photothermal-refractometric detector for HPLC.

Main Methods:

• Utilized a mode-mismatched parallel dual-beam thermal lens spectrometer with a far-field single-channel detector.
• Employed expert estimation for optical-scheme optimization.
• Investigated chelates and metal complexes using 4-(2-pyridylazo)resorcinol, Xylenol Orange, 4-(2-thiazolylazo)resorcinol, and dithizone as reagents.
• Developed a combined photothermal-refractometric detector based on a polarization interferometer.

Main Results:

• Achieved limits of detection in the n x 10(-8) - n x 10(-7) mol L(-1) range for chelates.
• Demonstrated relative standard deviations of 3-7% in ion chromatography with improved linear calibration ranges (three orders).
• Showcased superior sensitivity of photothermal detection compared to traditional photometric and absorption detectors for metal complexes and sugars.

Conclusions:

• Optimized thermal lens spectrometry provides high sensitivity and repeatability for HPLC.
• Photothermal detection, particularly with a combined photothermal-refractometric system, offers significant advantages over conventional detectors.
• The developed methods are effective for determining metal complexes and sugars with high sensitivity.