Fully packed capillary electrochromatographic microchip with self-assembly colloidal silica beads.

Area of Science:

• Analytical Chemistry
• Microfluidics
• Separation Science

Background:

• Capillary electrochromatography (CEC) offers high separation efficiency but often faces challenges in chip fabrication and handling.
• Developing user-friendly microfluidic devices with robust packing materials is crucial for routine analysis.

Purpose of the Study:

• To develop a fully packed CEC microchip with enhanced solution and chip handling capabilities.
• To demonstrate the effectiveness of a self-assembly packing technique for colloidal silica beads in microchannels.
• To evaluate the separation performance of the fabricated CEC microchip for complex mixtures.

Main Methods:

• Microchannels were fabricated on a cyclic olefin copolymer substrate using injection molding.
• 0.8-microm monodisperse colloidal silica beads were packed into microchannels via a self-assembly technique.
• The packed chip was sealed, filled with buffer solution using self-priming capillary action, and tested with FITC-derivatized amino acids.

Main Results:

• The fabricated CEC microchip exhibited improved solution and chip handling.
• The self-assembly packing acted as a built-in nanofilter, simplifying sample and buffer loading.
• Reproducible electroosmotic flow control was achieved (1.3% rsd in migration rate) due to the silica packing's high surface area-to-volume ratio.
• Successful separation of FITC and four FITC-derivatized amino acids was demonstrated within a 2-mm separation channel.

Conclusions:

• The developed CEC microchip provides a practical and efficient platform for microscale separations.
• The self-assembly packing technique is a viable method for creating robust and functional packed microfluidic devices.
• This technology holds promise for simplified sample preparation and analysis in various chemical and biological applications.