A quadrupole ion trap/time-of-flight mass spectrometer with a parabolic reflectron

✍ Scribed by Doroshenko, Vladimir M.; Cotter, Robert J.

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 470 KB
• Volume: 33
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/(sici)1096-9888(199804)33:4<305::aid-jms635>3.0.co;2-9

✦ Synopsis

A matrix-assisted laser desorption/ionization-quadrupole ion trap/reÑectron time-of-Ñight (MALDI-QIT/reTOF) mass spectrometer design and its operation in both normal and tandem mass spectrometric modes are described. A parabolic reÑectron was found to be capable of providing mass resolution of 5000 for an initial ion energy distribution ranging over a 50% energy interval of the entire reÑectron energy range. The sensitivity, ion isolation and fragmentation efficiency in the MALDI-QIT/reTOF instrument were close to those observed in the MALDI/QIT mass spectrometer. The mass resolution was shown to depend on the extraction Ðeld potentials, the r.f. trapping voltage amplitude and the phase of shutting down the r.f. voltage before extraction. At values of the q z AE 0.3-0.4 mass resolution does not depend on the ion mass, is in a range of 1000-1400 and is governed by the extraction voltages and the ion temperature before extraction, the latter shown to be in the range 1180-1690 K. The variation of the mass resolution for ions at values of is irregular but normally it is lower than that for ions having q z > 0.4 lower values. Mass spectral line positions shifted when the trapping voltage before extraction was varied. The q z line shifts were larger for lower mass ions and were comparable to the line widths in the case of very low masses. 1998