Integration of electropreconcentration and electrospray ionization in a microchip

Area of Science:

• Analytical Chemistry
• Microfluidics
• Mass Spectrometry

Background:

• Sensitive detection of analytes is crucial in mass spectrometry (MS).
• Microfluidic devices offer miniaturized platforms for chemical analysis.
• Integrating sample preconcentration with ionization techniques can improve MS sensitivity.

Purpose of the Study:

• To develop a microfluidic glass chip for sensitive mass spectrometry (MS).
• To integrate nanochannel-based electropreconcentration with electrospray ionization (ESI).
• To enhance MS signal detection for cation analytes.

Main Methods:

• Fabrication of a microfluidic chip with micro-nano-microchannel junctions.
• Coating the junction with polyE-323 to reverse electroosmotic flows and prevent adsorption.
• Utilizing a field-free electrokinetic pump for analyte delivery.
• Performing preconcentration-electrospray ionization-mass spectrometry (PESI-MS).

Main Results:

• Achieved one order of magnitude signal enhancement in MS signal.
• Demonstrated stable positive electrospray ionization (ESI) with negligible dead volume.
• Successfully preconcentrated cation analytes in acidic buffer conditions (pH ~3).

Conclusions:

• The developed microfluidic chip effectively enhances MS sensitivity through integrated preconcentration and ESI.
• The polyE-323 coating and electrokinetic pump are key to stable and efficient analyte delivery.
• This technology shows promise for sensitive peptide analysis using mass spectrometry.