Deep‐ultraviolet laser ablation electrospray ionization mass spectrometry

R.O. Lawal, F. Donnarumma, K.K. Murray, Deep-ultraviolet laser ablation electrospray ionization mass spectrometry, J. Mass Spectrom. 54 (2019) 281–287. doi:10.1002/jms.4338.

A 193‐nm wavelength deep ultraviolet laser was used for ambient laser ablation
electrospray ionization mass spectrometry of biological samples. A pulsed ArF excimer
laser was used to ablate solid samples, and the resulting plume of the desorbed material
merged with charged electrospray droplets to form ions that were detected with a
quadrupole time‐of‐flight mass spectrometer. Solutions containing peptide and protein
standards up to 66‐kDa molecular weight were deposited on a metal target,
dried, and analyzed. No fragmentation was observed from peptides and proteins as
well as from the more easily fragmented vitamin B12 molecule. The mass spectra
contained peaks from multiply charged ions that were identical to conventional
electrospray. Deep UV laser ablation of tissue allowed detection of lipids from
untreated tissue. The mechanism of ionization is postulated to involve absorption of
laser energy by a fraction of the analyte molecules that act as a sacrificial matrix or
by residual water in the sample.