Two-Laser Matrix Assisted Laser Desorption/Laser Ionization Time-of-Flight MassSpectrometry of Biomolecules

摘要

Recent efforts to detect and identify large biomolecules using matrix assistedlaser desorption have shown MALDI to be an extremely sensitive technique for trace detection from a solid sample. In the DI process, ions are formed by proton transfer from an electronically excited organic acid to a suitable proton accepting analyte. However, detection and characterization of biomolecules may benefit from ionization of the isolated unprotonated gas phase neutrals. To this end, a custom time-of-flight mass spectrometer as been constructed to perform two-laser matrix assisted laser desorption/laser ionization studies using separate desorption and ionization lasers. The two chamber, differentially pumped apparatus incorporates numerous laser and sample probe entry ports, a pulsed valve, and a modified Wiley-NcLaren mass spectrometer design. Results of initial two-laser experiments on phenylalanine in a sinnapinic acid matrix have demonstrated the apparatus' ability to detect laser ionization of laser desorbed neutrals.