Watch the Real-Time Acuisition of a FD Mass Spectrum

acquisition of a FD mass spectrum

This animation shows the "real-time" acquisition of a FD mass spectrum. The original time scale has been reduced by a factor of 3, i.e., the data has been acquired at 14 s per scan cycle from m/z 50-2000. The acquisition starts at 2 mA emitter current and the emitter is heated up by continuously raising this current at a rate of 8 mA/min. The upper trace represents the TIC which would normally build up while the measurement proceeds. The lower portion shows the actual mass spectrum. The spectrum counter is indicated on the TIC trace and in the gray bar above the mass spectrum. The molecular ion of the analyte, m/z 571.9, is already observed in the first spectrum but it takes until scan No.14 to reach a high level of desorption. This point is known as "best anode temperature" (BAT). Have a look at the absolute intensity scale (left upper corner of the mass spectrum) and on the signal-to-noise ratio! After scan No.19, there is no more sample left on the emitter and the spectrum approaches pure noise again. The final spectrum represents the sum over scans No. 14-19 and it is zoomed in to the molecular ion region. The isotopic pattern of the molecular ion fits well for the expected composition C30H21BrFe2.
The example has been taken from: F. Siegler, J. J. Wolff, J. H. Gross, "Analysis of ferrocenyl compounds by LR and HR field desorption mass spectrometry", Adv. Mass Spectrom. 14, \PROCS\IMSC_B\B08_3140.PDF (353 kB), (1998).

08 June 2005