Coupling Microchip Electrospray Ionization Devices with High Pressure Mass Spectrometry.

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Microfluidics

Background:

• High-pressure mass spectrometry (HPMS) offers unique analytical capabilities.
• Integrating microchip devices with MS can enhance sample handling and analysis speed.
• Miniature mass spectrometers require robust inlet systems for efficient ion transfer.

Purpose of the Study:

• To couple a microchip electrospray ionization (ESI) source with a high-pressure mass spectrometry (HPMS) system.
• To develop and evaluate a continuous atmospheric inlet for ion transfer.
• To assess the performance of a miniature cylindrical ion trap (mini-CIT) mass spectrometer for analyzing biomolecules.

Main Methods:

• A microchip ESI source was interfaced with an HPMS system using a stainless steel capillary and DC ion optics.
• Amino acids and peptides were infused and analyzed using a mini-CIT MS operating at ≥1 Torr with air as the buffer gas.
• Microchip capillary electrophoresis (CE) separation coupled with mini-CIT detection was performed and compared to a commercial instrument (Waters Synapt G2).

Main Results:

• The mini-CIT detector successfully spanned a mass range from m/z 75 to 681, detecting glycine and thymopentin.
• Comparable separation efficiencies were achieved between the mini-CIT and the commercial Synapt G2.
• The mini-CIT system exhibited wider peak widths than the Synapt G2, consistent with high-pressure operation, and a lower signal-to-noise ratio (approximately 6x).

Conclusions:

• The developed microchip ESI-HPMS system is capable of analyzing amino acids and peptides.
• The mini-CIT MS demonstrates potential for high-pressure analytical applications, despite lower signal-to-noise compared to commercial systems.
• Further optimization of the mini-CIT system could improve sensitivity and peak resolution for broader applications in chemical and biological analysis.