An end-channel amperometric detector for microchip capillary electrophoresis

Area of Science:

• Analytical Chemistry
• Microfluidics
• Electrochemistry

Background:

• Microchip capillary electrophoresis (MCCE) offers miniaturized and efficient separation capabilities.
• Amperometric detection is a sensitive technique for analyzing electroactive species like neurotransmitters.
• Integration of electrodes on microchips presents challenges in alignment and fixation.

Purpose of the Study:

• To design and fabricate a home-made glass microchip with an integrated end-channel amperometric detector for enhanced neurotransmitter analysis.
• To evaluate the performance and optimize separation parameters for neurotransmitters using the developed MCCE system.
• To demonstrate the utility of the microchip for sensitive and selective detection of dopamine, catechol, and epinephrine.

Main Methods:

• Fabrication of a glass microchip using a two-step etching process to create a detection reservoir with an integrated guide tube for the working electrode.
• Integration of a 30 µm carbon fiber microdisk working electrode and a Pt cathode into the amperometric detector.
• Optimization of separation parameters including injection time, buffer composition, and pH for baseline separation of neurotransmitters.
• Electrochemical characterization and performance evaluation using standard neurotransmitter solutions.

Main Results:

• Successful baseline separation of dopamine (DA), catechol (CA), and epinephrine (EP) within 80 seconds.
• Achieved relative standard deviations of ≤6.0% for peak currents and migration times, indicating good reproducibility.
• Demonstrated linear responses for DA (5–200 µM) and CA (20–800 µM).
• Obtained low limits of detection: 0.51 µM for DA and 2.9 µM for CA (S/N=3).

Conclusions:

• The developed home-made microchip capillary electrophoresis system with an integrated amperometric detector is effective for rapid and sensitive neurotransmitter analysis.
• The integrated guide tube design simplifies working electrode fixation and alignment, improving device fabrication.
• The system shows promise for practical applications in analyzing biological samples containing neurotransmitters.