Unprecedented Ionization Processes in Mass Spectrometry Provide Missing Link between ESI and MALDI.

Area of Science:

• Analytical Chemistry
• Biophysics
• Proteomics

Background:

• Producing intact, highly-charged protein ions from surfaces is challenging in mass spectrometry.
• This capability is crucial for applications in biomedical and clinical research.

Purpose of the Study:

• To report the successful formation of intact, highly-charged protein ions using high vacuum time-of-flight mass spectrometry.
• To investigate experimental conditions for effective matrix removal and stable ion formation.

Main Methods:

• Utilized high vacuum time-of-flight mass spectrometry in linear and reflectron modes.
• Employed experimental conditions facilitating effective matrix removal from sample surfaces and charged clusters.
• Investigated the role of matrix volatility in ion formation.

Main Results:

• Achieved the highest reported charge states for intact protein ions on high vacuum mass spectrometers.
• Observed charge states approximately one-third of those obtained with matrix-assisted laser desorption/ionization at atmospheric pressure.
• Demonstrated the formation of abundant and stable highly-charged ions.

Conclusions:

• Effective matrix removal and matrix volatility are key factors for generating highly-charged protein ions in high vacuum.
• The ionization process shows mechanistic links to electrospray ionization and matrix-assisted laser desorption/ionization.
• This method advances protein analysis capabilities in mass spectrometry.