Matrix-assisted ultraviolet laser desorption of non-volatile compounds

Abstract The use of a matrix for pulsed ultraviolet laser desorption mass spectrometry is shown to extend its applicability into the range of larger, thermally labile biomolecules. The matrix compounds tested show strong resonance absorption at the laser wavelength of 266 nm and can be either solid or liquid. Characteristic features of the matrix-assisted LD mass spectra are high quasimolecular ion yield with little or no fragmentation and only a few signals in the low mass range. The matrix effect is discussed in the light of three possible mechanisms: an effective and controllable energy transfer of the laser energy to the condensed phase by predominantly one-photon absorption, the creation of a uniform and soft disintegration of the condensed phase at moderate irradiances independent of the analyte's individual properties, and an enhancement of ionization yield by protonation via excited state molecules.