1. MALDI demonstration Frímann, Helgi, Long, Nanna

2. Sample preperation The sample of interest and matrix are dissolved in a volatile solvent The sample/matrix/solvent mixture is then spotted on a metal plate When the solvent has evaporated you can put your plate in to the vacuum Anchor chips have hydrophilic area surrounded by hydrophobic ring

4. Matrix Assisted Laser Desorption/ Ionization Introduced by M. Karas and F. Hillenkamp in 1985 [1] Mainly used for large molecules Soft ionization The vibrational energy added to the analyte molecule is about 4eV [2] The ions formed are typically: [M+H] +, [M+Na] +, [M+K] +, [M+NH 4 ] + or [M-H] - Ionization mechanism is not fully understood

6. TOF mass spectrometer A TOF MS is usually (always?) used with MALDI Reflectron TOF MSMS Microchannel plate electron multiplier (10000 electrons for each ion) MALDI-TOF “records”: ~300.000 amu, attomoles of material

9. Electron multiplier

11. Measurements The data we have is from the protein BSA (Bovine serum albumin) We took linear spectra in the demostration Got the data from the peak at 927amu in MSMS mode

17. References [1] Karas, M.; Bachmann, D.; Hillenkamp, F. (1985). "Influence of the Wavelength in High-Irradiance Ultraviolet Laser Desorption Mass Spectrometry of Organic Molecules".Anal Chem 57: 2935–9 [2] I. Bald, J. Kopyra and E. Illenberger, Angewandte Chemie-International Edition 45 (29), 4851-4855 (2006).