The Bruker Ultraflex III is a single analyser dedicated Matrix Assisted Laser Desorption Ionisation Time of Flight mass spectrometer.
A solution of the sample is mixed with an excess of a UV active matrix and 0.5ul of this mixture is spotted on to the MALDI target plate, approximately 3ug of sample is applied to the plate. After evaporation of the solvent, the plate is introduced into the high vacuum of the mass spectrometer and irradiated by a UV laser. The radiation is strongly absorbed by the matrix and energy transferred to the sample, resulting in the sample being ejected from the surface of the plate. Sample ions are then extracted into the spectrometer for mass measurement.
The system can be operated in two modes, linear mode where the ions on leaving the ion source pass just once down a flight tube to a detector and reflectron mode where the ions are reflected back along the flight tube for a second pass before arriving at a second detector. Both modes can detect either positive or negative ions in a single analysis. MALDI tends to give [MH]+ or [M+Na]+ in positive ion mode. In negative ion, [M-H]- ions are usually observed.
MALDI is a ‘soft ionisation’ process typically used to provide nominal mass spectra of intact proteins, polymers and fullerene based molecules, it is not suited for the analysis of low molecular weight samples or liquids.
Additional information for UoN users can be found here.
Model: Ultraflex III