A flow-through column electrolytic cell for supercritical fluid chromatography

Area of Science:

• Electrochemistry
• Analytical Chemistry
• Chromatography

Background:

• Supercritical fluid chromatography (SFC) requires sensitive detection methods.
• Electrochemical detection offers high sensitivity but can be challenging in SFC systems.
• Developing robust and efficient flow-through cells is crucial for SFC applications.

Purpose of the Study:

• To propose and evaluate a novel flow-through column electrolytic cell as a detector for supercritical fluid chromatography.
• To fabricate and characterize electrodes made from carbon strings for electrochemical sensing.
• To assess the performance of the developed cell in terms of sensitivity and linearity.

Main Methods:

• Fabrication of a flow-through electrolytic cell with working and counter electrodes made from carbon strings (192 strings, 400 carbon fibers each, 10 μm diameter).
• Assembly of the cell using polyether ether ketone (PEEK) blocks and polytetrafluoroethylene (PTFE) membrane filters for electrode separation.
• Integration of the cell into a supercritical fluid chromatography system for detecting ferrocene standards.
• Elution of ferrocene using supercritical CO2 and methanol/ammonium acetate mobile phase.

Main Results:

• The electrochemical cell generated current signals proportional to ferrocene concentration.
• A linear correlation (r = 0.999) was observed between the current peak area and ferrocene concentration in the range of 10-400 μmol/L.
• The limit of detection (LOD) for ferrocene on the column was determined to be 9.8 × 10⁻¹³ mol (S/N = 3).

Conclusions:

• The novel flow-through column electrolytic cell is a sensitive and effective detector for supercritical fluid chromatography.
• Carbon string electrodes offer a viable material for constructing electrochemical detectors in SFC.
• The developed system demonstrates excellent linearity and a very low limit of detection, suitable for trace analysis.