Fluorescently Labeling Amino Acids in a Deep Eutectic Solvent

Area of Science:

• Analytical Chemistry
• Green Chemistry

Background:

• Deep eutectic solvents (DESs) offer novel sample preparation methods.
• Compatibility of DESs with common analytical techniques like fluorescent labeling remains a challenge.

Purpose of the Study:

• To evaluate the effectiveness of traditional fluorescent labels for amino acid derivatization in common DESs.
• To optimize conditions for labeling and subsequent analysis of amino acids in DES matrices.

Main Methods:

• Investigated three fluorescent labels for amino acid derivatization in choline chloride-ethylene glycol DESs.
• Optimized reaction conditions for labeling both D- and L-amino acids.
• Utilized capillary electrophoresis (CE) for sensitive detection of labeled amino acids.

Main Results:

• Two fluorescent labels, fluorescein isothiocyanate and 5-carboxyfluorescein succinimidyl ester, effectively labeled amino acids in DESs.
• Successful labeling achieved for amino acid concentrations as low as 4 μM.
• Capillary electrophoresis detected analytes at concentrations down to 50 nM without DES removal.

Conclusions:

• Demonstrated the feasibility of fluorescent labeling and CE separation of amino acids directly within a DES matrix.
• This represents the first successful complete fluorescent labeling reaction and CE separation in a DES.
• Highlights the potential of DESs in analytical chemistry workflows.