Porous polymer monolith assisted electrospray from a glass microdevice

Area of Science:

• Analytical Chemistry
• Microfluidics
• Mass Spectrometry

Background:

• Coupling microfluidic devices with nanoelectrospray ionization mass spectrometry (nESI-MS) offers automation potential.
• Previous coupling methods required complex fabrication like drilling or integrated emitters.
• A simplified, robust coupling method is needed for routine analytical procedures.

Purpose of the Study:

• To develop an easy-to-fabricate nanospray emitter for microfluidic devices.
• To demonstrate the effectiveness of porous polymer monoliths (PPMs) for stable electrospray generation.
• To improve the automation of analytical procedures using lab-on-a-chip (LOC) systems coupled to mass spectrometry.

Main Methods:

• Fabrication of a nanospray emitter using a photo-patterned porous polymer monolith (PPM) at the end of a glass microdevice.
• Testing stable electrospray generation across various flow rates (50-500 nL/min).
• Evaluating performance using leucine-enkephalin and PPG with total ion current traces and mass spectra analysis.

Main Results:

• Achieved stable electrospray at flow rates compatible with electroosmotic flow (50-100 nL/min).
• Demonstrated low relative standard errors (4%) and good signal-to-noise ratios (S/N 43) from minimal sample amounts (2 fmol).
• Showcased high repeatability (13% variability) across multiple experiments and reduced sprayer clogging due to PPM's structure.

Conclusions:

• Porous polymer monoliths provide a simple and effective method for fabricating nanospray emitters for microfluidic devices.
• This approach facilitates the automation of analytical procedures by enabling robust coupling with nanoelectrospray ionization mass spectrometry.
• The developed method offers improved stability, sensitivity, and repeatability for microfluidic-based mass spectrometry analyses.