LASER-DESORPTION MASS-SPECTROMETRY ON THIN LIQUID JETS

A recently developed soft desorption method for mass spectrometry is p resented, which is called Laser Induced Liquid Beam Ionization/Desorpt ion (LILBID). Analyte ions are desorbed from a thin jet of analyte sol ution directly into vacuum by means of an IR laser pulse, which has be en tuned to a vibrational resonance of the solvent. A comparative expe riment with ammonium chloride and aniline hydrochloride shows that ion formation via proton transfer takes place in the solution. Thermally unstable compounds, as well as supra-and biomolecular complexes, can b e detected intact and mass analyzed in a reflectron time-of-flight (Re -TOF) mass spectrometer. During the desorption process, noncovalent in teractions and some solvation characteristics are preserved. Three exa mples for the capacity of LILBTD are given in this short overview: (a) ion-solvent interactions with the formation of a clathrate structure Cs+(H2O)(20), (b) host-guest interactions with the K+ selectivity of v alinomycin, and (c) noncovalent interactions with the dimerization of gramicidin.