Universal acoustic flame detection for modified supercritial fluid chromatography

Area of Science:

• Analytical Chemistry
• Chromatography

Background:

• Supercritical-fluid chromatography (SFC) requires sensitive and universal detection methods.
• Existing detectors like flame ionization detectors (FID) have limitations, especially with organic modifiers.

Purpose of the Study:

• To characterize a novel acoustic flame detector (AFD) for its utility in SFC.
• To evaluate the AFD's performance with various analytes and mobile phases, including modified supercritical-carbon dioxide (SC-CO(2)).

Main Methods:

• An oscillating premixed hydrogen/oxygen flame was utilized as the basis for the acoustic flame detector.
• The SFC-AFD system was tested using standard hydrocarbon analytes and both pure and methanol-modified SC-CO(2) mobile phases.
• Detector response, linearity, detection limits, and baseline stability were assessed.

Main Results:

• The AFD exhibited a linear response over three orders of magnitude with a detection limit of 18 ng of carbon per second.
• Detector sensitivity remained uniform across different analytes and mobile phases (pure or methanol-modified SC-CO(2)).
• Baseline shifts occurred with density gradients, particularly when using methanol modifiers.

Conclusions:

• The acoustic flame detector is a potentially useful, inexpensive universal detector for SFC.
• It is particularly suitable for SFC applications employing organic modifiers where FIDs are not viable.
• Further investigation into baseline stability under gradient conditions may be warranted.