A microchip-based flow injection-amperometry system with mercaptopropionic acid modified electroless gold...

Area of Science:

• Analytical Chemistry
• Electrochemistry
• Microfluidics

Background:

• Accurate determination of dopamine (DA) is crucial in various biological and chemical analyses.
• Ascorbic acid (AA) often interferes with DA detection, necessitating selective analytical methods.
• Existing methods for DA determination can be time-consuming and lack selectivity.

Purpose of the Study:

• To develop a novel chip-based flow injection analysis (FIA) system for automatic, rapid, and selective dopamine determination.
• To enhance the selectivity of an electrochemical detector (ED) for DA in the presence of AA.
• To optimize the performance of the microfluidic chip-based FIA system.

Main Methods:

• Fabrication of a polycarbonate (PC) microfluidic chip with an integrated electrochemical detector (ED).
• Modification of the gold working microelectrode using a self-assembled monolayer (SAM) of 3-mercaptopropionic acid (MPA) for enhanced selectivity.
• Investigation of postplating treatment methods for high-quality SAM formation.
• Optimization of detection potential, flow rate, and sampling volume.

Main Results:

• Achieved a low detection limit of 74 nmol L(-1) for dopamine under optimal conditions.
• Demonstrated a high sample throughput rate of 180 samples per hour.
• Obtained a low relative standard deviation (RSD) of 0.9% for peak heights over 19 runs.
• Showed interference-free determination of DA possible when the AA-DA concentration ratio is ≤10.

Conclusions:

• The developed chip-based FIA system provides a robust platform for selective and rapid dopamine analysis.
• Electrode modification with MPA-SAM significantly improves the selectivity of the electrochemical detector.
• The system is suitable for applications requiring sensitive and interference-free dopamine determination.