Cold-spray ionization mass spectrometry: principle and applications.

Area of Science:

• Analytical Chemistry
• Physical Chemistry
• Biochemistry

Background:

• Characterizing labile organic species in solution is challenging due to their instability.
• Conventional electrospray ionization mass spectrometry (ESI-MS) is often unsuitable for heat- and air-sensitive compounds.
• Understanding solution structures is crucial for reaction mechanisms and molecular interactions.

Purpose of the Study:

• To introduce and demonstrate the utility of cold-spray ionization mass spectrometry (CSI-MS) for analyzing labile organic species.
• To investigate the solution structures of various unstable compounds, including reagents, intermediates, catalysts, supramolecules, and biomolecules.
• To highlight the advantages of CSI-MS over conventional methods for specific analytical challenges.

Main Methods:

• Cold-spray ionization mass spectrometry (CSI-MS), a low-temperature variant of ESI-MS (approx. -80 to 10 °C).
• Direct analysis of solution samples without extensive sample preparation.
• Mass spectrometry for identifying molecular ions and adducts.

Main Results:

• CSI-MS successfully characterized labile organic species, including unstable reagents, reaction intermediates, and asymmetric catalysts.
• Highly ordered supramolecules, intractable by conventional ESI, yielded multiply charged ions with solvent molecules attached.
• Key structures of Grignard reagents in THF solution were identified.
• Primary biomolecules (nucleosides, amino acids, sugars, lipids) revealed singly charged Na(+) adducts of large, non-covalently linked clusters.

Conclusions:

• CSI-MS is a powerful direct solution analysis method for labile organic species and biomolecules.
• The low-temperature operation of CSI-MS preserves delicate non-covalent interactions and molecular integrity.
• CSI-MS provides unique insights into the solution-phase constitution of challenging chemical and biological systems.