Electrochemical detection method for nonelectroactive and electroactive analytes in microchip electrophoresis

Area of Science:

• Analytical Chemistry
• Electrochemistry
• Separation Science

Background:

• Microchip capillary electrophoresis (MCE) is a powerful separation technique.
• Sensitive detection of analytes, especially nonelectroactive ones, remains a challenge in MCE.
• Existing amperometric detection methods often require direct electroactivity of analytes.

Purpose of the Study:

• To develop a novel indirect amperometric detection method for MCE.
• To enable sensitive detection of both electroactive and nonelectroactive analytes.
• To investigate the unique electrochemical behavior of a carbon fiber electrode in a microchannel.

Main Methods:

• A single carbon fiber disk working electrode was integrated into the end of a microchannel for in-channel amperometric detection.
• The method utilizes the amperometric response of dissolved oxygen for indirect detection of nonelectroactive species.
• Direct amperometric detection of electroactive analytes was also performed on the carbon fiber electrode.

Main Results:

• The in-channel electrode configuration demonstrated distinct electrochemical behaviors for reduction and oxidation reactions, influenced by the separation electric field.
• The method successfully detected both electroactive and nonelectroactive analytes.
• Preliminary results showed a detection limit of 1.0 microM for potassium (K+) and sodium (Na+) ions.

Conclusions:

• The developed indirect amperometric detection method offers a sensitive and convenient approach for MCE.
• This technique is valuable for analyzing diverse analytes including inorganic cations and biomolecules.
• The method shows potential for determining electroosmotic flow rates.