# Deep Ultraviolet Laser Ablation Electrospray Ion Mobility Mass Spectrometry

## TL;DR

Researchers used a deep ultraviolet laser to ablate and ionize peptides and proteins for analysis with ion mobility mass spectrometry.

## Contribution

A new method combining deep ultraviolet laser ablation with electrospray ionization for intact biomolecule analysis is introduced.

## Key findings

- Laser ablated biomolecules remained intact without fragmentation.
- Multiply charged ions were observed similar to direct electrospray ionization.
- Ion mobility drift times were consistent between laser ablation and direct electrospray methods.

## Abstract

A solid-state
deep ultraviolet (DUV) optical parametric
oscillator
(OPO) at 206 nm wavelength was utilized for laser ablation electrospray
postionization of peptides and proteins coupled with ion mobility
mass spectrometry (IM-MS) analysis. Peptide and protein standard solutions
were spray deposited on quartz microscope slides to obtain thin, surface-coated
dry films. The pulsed laser irradiated the solid sample biomolecules
in transmission geometry, and the ablated surface material merged
with the electrospray plume for ionization before entering the IM-MS
instrument. Laser ablated biomolecules remained intact, and no fragmentation
was observed from the peptide or protein standards. The efficiency
of ionization was estimated at approximately 1% for instantaneous
ion signal; however, the signal was not stable over time. Mass spectra
of laser ablation electrospray for peptide and protein standards revealed
multiply charged ions similar to those observed in direct electrospray
ionization (ESI) MS. The ion mobility drift times for proteins from
laser ablation electrospray (LA-ESI) experiments were indistinguishable
from those observed in direct ESI.