Monolithic capillary column with an integrated electrochemical detector.

Area of Science:

• Electrochemistry
• Analytical Chemistry
• Separation Science

Background:

• Development of sensitive and robust electrochemical detectors is crucial for neurotransmitter analysis.
• Integrated microdetector systems offer advantages in sample handling and analysis time.

Purpose of the Study:

• To develop a monolithic capillary column with an integrated electrochemical detector for neurotransmitter analysis.
• To optimize the detection method for enhanced sensitivity and reliability.

Main Methods:

• Fabrication of a capillary column using carbon fiber and silver microwire electrodes.
• Integration of an electrochemical detector into the capillary column.
• Application of multiple pulse amperometry for sensitive detection.
• Chromatographic separation and quantification of neurotransmitters, specifically dopamine.

Main Results:

• The developed capillary device demonstrated stable and robust performance with low relative standard deviations (<1.5% for retention, <5.5% for resolution, <5.0% for detection signal).
• Multiple pulse amperometry enhanced sensitivity, achieving a limit of detection of 24 pg for dopamine.
• Reliable chromatographic separation of neurotransmitters was achieved, with a linear calibration curve for dopamine from 0.5 to 20.0 mgL⁻¹.
• Successful determination of dopamine in human urine samples using both calibration curve and standard addition methods, yielding consistent results (0.74±0.03 mgL⁻¹ and 0.71±0.02 mgL⁻¹).
• High precision was observed with intraday relative standard deviations <2.7% and interday relative standard deviations <3.6% over five days.

Conclusions:

• The integrated monolithic capillary column with an electrochemical detector is a sensitive and reliable tool for neurotransmitter analysis.
• The developed system offers excellent stability, robustness, and precision for dopamine determination.
• This technology holds promise for clinical applications, such as monitoring dopamine levels in biological samples like human urine.