Deep Ultraviolet Laser Ablation Electrospray Ion Mobility Mass Spectrometry.

Area of Science:

• Analytical Chemistry
• Biochemistry
• Spectrometry

Background:

• Direct electrospray ionization (ESI) is a common technique for analyzing biomolecules.
• Solid-state sample presentation offers potential advantages for certain analyses.
• Developing novel ionization methods is crucial for advancing mass spectrometry.

Purpose of the Study:

• To investigate laser ablation electrospray postionization (LA-ESI) for peptide and protein analysis using ion mobility mass spectrometry (IM-MS).
• To assess the efficiency and stability of LA-ESI for biomolecules.
• To compare LA-ESI results with direct ESI.

Main Methods:

• Solid-state deep ultraviolet (DUV) optical parametric oscillator (OPO) at 206 nm was used for laser ablation.
• Peptide and protein standards were deposited as dry films on quartz slides.
• Ablated material was merged with an electrospray plume for ionization before IM-MS analysis.

Main Results:

• Laser ablation electrospray postionization yielded intact multiply charged peptide and protein ions, similar to direct ESI.
• No significant fragmentation of biomolecules was observed during LA-ESI.
• Ion mobility drift times for proteins analyzed via LA-ESI were indistinguishable from those obtained by direct ESI.
• Ionization efficiency was estimated at ~1%, with observed signal instability.

Conclusions:

• LA-ESI is a viable method for ionizing peptides and proteins from solid samples without fragmentation.
• The technique produces comparable mass spectra and ion mobility data to direct ESI.
• Further optimization is needed to improve signal stability for routine applications.