Liquid beam desorption source for biomolecules

efficient source for MS investigations of biomolecules and their non covalently bound complexes

Weighing and analyzing biomolecules and their non covalently bound complexes via
laser induced liquid beam desorption mass spectrometry?

One technique that is emerging as a new and exciting method to study biomolecular non-covalent interactions and complexation is laser induced liquid beam desorption mass spectrometry. The experimental approach enables a gentle and soft desorption of neutrals, protonated molecular species, as well as their non-covalently bound complexes with an infrared laser pulse tuned to the OH-stretch vibration of liquid water.

In the case of protonated molecules or singly charged non-covalently bound aggregates post-desorption ionization with a second laser is not necessary for their sensitive detection via high resolution mass spectrometry. This is a significant advantage for analytic applications because it avoids fragmentation.

How does it work?

Goal:

Desorption of preformed ions or ionic aggregates of biomolecules in water solution (“chemical ionization“ instead of photoionization)

But:

Desorption of ions from bulk water is very difficult due to the large solvation energy, hot water destroys the biomolecules, however, Kw of water at high temperatures enhances protonation

Solution:

Heat the water “instantaneously“ via resonant excitation in the OH-stretch vibration with a pulsed laser, wait for the explosive expansion, and detect the (protonated) molecules (aggregates) via mass spectrometry.