Compact tunable Cr:LiSAF laser for infrared matrix-assisted laser desorption/ionization

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Laser Physics

Background:

• Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a powerful analytical technique.
• Mid-infrared laser sources offer unique advantages for MALDI-MS.
• Cr:LiSAF lasers provide tunable output in the mid-infrared region.

Purpose of the Study:

• To investigate the use of a tunable Cr:LiSAF laser-pumped optical parametric oscillator for mid-infrared MALDI-MS.
• To evaluate the performance of this system for analyzing biomolecules and synthetic polymers.
• To assess the signal quality and reproducibility of the MALDI-MS experiments.

Main Methods:

• Utilized a tunable Cr:LiSAF laser-pumped optical parametric oscillator.
• Performed mid-infrared MALDI-MS experiments on substance P, bovine insulin, and pd(T)10.
• Analyzed mass spectra in the 2.88-2.96 microns wavelength range.
• Assessed signal-to-noise ratio, resolution, and shot-to-shot reproducibility.

Main Results:

• Achieved excellent single-shot signal quality, including high signal-to-noise ratio and resolution.
• Observed poor shot-to-shot reproducibility in the MALDI-MS experiments.
• Found no correlation between the absorption spectrum of the matrix and the MALDI response.

Conclusions:

• A tunable Cr:LiSAF laser is suitable for mid-infrared MALDI-MS, providing high-quality individual spectra.
• Shot-to-shot reproducibility requires further optimization, likely through laser design improvements.
• The matrix absorption spectrum does not appear to be a limiting factor for MALDI response in this setup.