Improved hydrostatic pressure sample injection by tilting the microchip towards the disposable miniaturized CE device

Area of Science:

• Analytical Chemistry
• Microfluidics
• Separation Science

Background:

• Microchip capillary electrophoresis (CE) offers miniaturized and portable analytical capabilities.
• Efficient sample injection is crucial for reproducible microchip CE separations.
• Existing injection methods often require complex instrumentation or external hardware.

Purpose of the Study:

• To develop a simple, hardware-free hydrostatic pressure-based sample injection method for disposable microchip CE.
• To investigate the influence of key parameters on the injection process.
• To validate the method's feasibility and reproducibility for analytical applications.

Main Methods:

• A disposable microchip CE device was tilted to generate hydrostatic pressure for sample injection.
• The effects of tilt angle, initial liquid height, and injection duration were systematically studied.
• Fluorescence and electrochemical detection were used to analyze dopamine and catechol, verifying injection performance.

Main Results:

• Hydrostatic pressure effectively drove sample injection into the microchip.
• Injection plug stability was primarily dependent on injection duration and tilt angle.
• The method demonstrated good reproducibility for dopamine and catechol analysis.
• Performance was largely independent of initial liquid heights when sufficient injection time was used.

Conclusions:

• The developed tilted microchip hydrostatic pressure injection is a simple and effective technique.
• It eliminates the need for additional hardware, making it suitable for disposable devices.
• This method offers a promising approach for simplified sample handling in portable CE systems.