Fabrication of a monolithic sampling probe system for automated and continuous sample introduction in microchip-based...

Area of Science:

• Analytical Chemistry
• Microfluidics
• Separation Science

Background:

• Developing efficient sample introduction systems is crucial for chip-based capillary electrophoresis (CE).
• Traditional methods often face limitations in throughput and sample consumption.

Purpose of the Study:

• To develop a simple fabrication process for monolithic sampling probes on glass microfluidic chips.
• To integrate these chips with a continuous sample presentation system for chip-based CE.
• To evaluate the system's performance for high-throughput analysis of FITC-labeled amino acids.

Main Methods:

• Fabrication of monolithic sampling probes on glass chips using basic tools.
• Integration of microfluidic chips with a slotted-vial array for continuous sample introduction.
• Utilizing on-chip reservoirs for stable hydrostatic pressure during prolonged operation.
• Demonstration using FITC-labeled amino acids with Laser-Induced Fluorescence (LIF) detection.
• Application of gradient CE for enhanced separation efficiency.

Main Results:

• Achieved high throughput of 30-60 samples per hour with low carry-over (<1.0%).
• Demonstrated excellent reproducibility in peak height (3.3-3.6% RSD) and long-term analysis (6.8-7.5% RSD).
• Obtained extremely low sample consumption (30 nL per analysis).
• Reported separation efficiencies in the range of 0.8-2x10^5 plates/m.
• Gradient CE showed improved separation efficiency compared to isocratic methods.

Conclusions:

• The developed fabrication process and integrated system enable efficient, high-throughput, and low-consumption continuous analysis in chip-based CE.
• The system is versatile, applicable for both sample introduction and generating gradients for improved separations.
• This approach offers a significant advancement for automated and rapid analysis in microfluidic systems.