Pharmacology and Molecular Sciences

What is a mass spectrometer? ion source mass analyzer detector Chemical TOF: time-of-flight multiplier EI: electron impact ITMS: ion trap mass spectrometer channelplate CI: chemical ionization FTMS: Fourier transform mass spectrometer Biological …. and combinations of these (QTOF, TOF/TOF, IT/TOF) MALDI: matrix-assisted laser desorption/ionization ESI: electrospray ionization AP/MALDI: atmospheric pressure MALDI a balance for weighing molecules vacuum system 23 MALDI is one method for ionizing peptides and other biomolecules Matrix-assisted laser desorption/ionization MALDI mechanism 1. The matrix absorbs UV or IR energy from the pulsed laser 2. The matrix ionizes and dissociates; it undergoes a phase change to a supercompressed gas; charge is passed to some of the analyte molecules 3. Matrix expands at supersonic velocity; additional analyte ions are formed in the gas phase; ions are entrained in the expanding plume laser peptide matrix