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Investigation into factors affecting precision in ion trap mass spectrometry using different scan directions and axial modulation potential amplitudes
Author(s) -
Dobson G.,
Murrell J.,
Despeyroux D.,
Wind F.,
Tabet J.C.
Publication year - 2004
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.686
Subject(s) - chemistry , ion , ion trap , quadrupole ion trap , mass spectrometry , atomic physics , amplitude , dissociation (chemistry) , mass spectrum , analytical chemistry (journal) , optics , physics , organic chemistry , chromatography
Abstract Electrospray ionization mass spectra obtained from different scan directions are observed to be dependent on the axial modulation potential amplitudes used for resonant ejection and on the positive deviation caused by higher even‐multipole fields present in most commercial ion traps. The axial modulation voltage influences the dissociation of ions during resonant ejection and the observed mass shifts. The higher even‐multipole fields in commercial ion traps are known to influence resonant ejection from the ion trap and can cause a loss in mass resolution for peaks in reverse scan mass spectra compared with that obtained by the forward scan. However, along with the dissociation of ions during resonant ejection causing a loss in resolution, the possibility of resolving an isotopic distribution is also shown to be influenced by the mass shifts caused by the space charge. These mass shifts differ depending on the scan direction employed. A significant loss in resolution can also result from resonant ejection using non‐optimal axial modulation voltages. We also present results showing the ejection of ions at $\beta_{z} = {1 \over 2}$ using the reverse scan mode without the axial modulation voltage. Ion ejection at $\beta_{z} = {1 \over 2}$ is uncommon in commercial (stretched ion traps) with the conventional analytical scan without the use of a frequency of the axial modulation voltage corresponding to this non‐linear resonance. Copyright © 2004 John Wiley & Sons, Ltd.