An ion funnel interface for improved ion focusing and sensitivity using electrospray ionization mass spectrometry

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Interface Science

Background:

• Electrospray ionization (ESI) is a key technique for analyzing biomolecules.
• Improving the sensitivity of ESI-mass spectrometry (MS) interfaces remains a critical challenge.
• Current interfaces face limitations in ion transmission efficiency.

Purpose of the Study:

• To develop and evaluate a novel electrohydrodynamic ion funnel interface for ESI-MS.
• To enhance ion focusing and transmission efficiency from the ESI source into the mass analyzer.
• To assess the performance improvement using a triple-quadrupole mass spectrometer.

Main Methods:

• Design and implementation of an electrohydrodynamic ion funnel with serially arranged ring electrodes.
• Application of radiofrequency (rf) and direct current (dc) electric potentials to the electrodes.
• Operation within a 1-10 Torr pressure range to facilitate collisional damping and ion focusing.
• Performance evaluation using ion current measurements and mass spectra, including protein solutions.

Main Results:

• The ion funnel effectively focuses and transmits ions as a collimated beam.
• Achieved over a 10-fold increase in signal intensity compared to standard inlet capillary-skimmer configurations.
• Demonstrated m/z discriminating parameters, providing low- and high-m/z cutoffs.
• Successful analysis of protein solutions with significantly improved signal-to-noise ratios.

Conclusions:

• The electrohydrodynamic ion funnel represents a significant advancement in ESI-MS interface technology.
• The developed interface offers greatly improved ion transmission efficiency.
• Potential to achieve near 100% ion transmission for analytically relevant ions is feasible.