Rugged gap reactor device for postcolumn fluorescence detection in capillary electrophoresis

Area of Science:

• Analytical Chemistry
• Separation Science

Background:

• Capillary electrophoresis (CE) is a powerful separation technique.
• Postcolumn derivatization enhances detection sensitivity for analytes like amino acids.
• Developing robust and user-friendly derivatization devices is crucial for routine CE applications.

Purpose of the Study:

• To describe the construction and performance of a novel, rugged device for postcolumn derivatization in CE.
• To demonstrate the device's capability for sensitive amino acid analysis.
• To assess the device's suitability for routine laboratory use.

Main Methods:

• A gap-design device for postcolumn derivatization was constructed, featuring a sub-micron gap created without micromanipulation.
• Derivatizing reagent delivery was controlled via gravity flow, electroosmotic flow, and liquid level height.
• Amino acids were derivatized using o-phthaldialdehyde/2-mercaptoethanol and detected using a modified HPLC fluorescence detector.

Main Results:

• The device demonstrated excellent performance, yielding theoretical plate numbers between 40,000 and 250,000 for 11 separated amino acids.
• A detection limit of 6.7 × 10⁻⁷ mol/L for glycine (S/N = 2) was achieved.
• The device was successfully applied to determine free amino acids in a real-world wine sample.

Conclusions:

• The developed rugged postcolumn derivatization device is effective for sensitive amino acid analysis in CE.
• The simple construction and stable performance suggest its applicability for routine analytical laboratory work.
• This CE derivatization device offers a practical solution for enhancing analyte detection in complex samples.