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Influence of internal standard charge state on the accuracy of mass measurements in orthogonal acceleration time‐of‐flight mass spectrometers
Author(s) -
Charles Laurence
Publication year - 2007
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.3347
Subject(s) - chemistry , mass spectrometry , ion , time of flight mass spectrometry , ionization , time of flight , calibration , analytical chemistry (journal) , detector , spectrometer , acceleration , range (aeronautics) , atomic physics , noise (video) , ionization chamber , computational physics , optics , physics , chromatography , materials science , image (mathematics) , organic chemistry , quantum mechanics , classical mechanics , artificial intelligence , computer science , composite material
Accuracy of mass measurements performed in orthogonal acceleration time‐of‐flight (oa‐TOF) mass spectrometers highly depends on the quality of the signal and the internal calibration. The use of two reference compounds which bracket the targeted unknown, give rise to ions with sufficient signal‐to‐noise ratio while avoiding detector saturation and produce signals of similar intensity as compared to the target is a common requirement which allow a 5 ppm accuracy on a routine basis. Ion charge state is demonstrated here to be an additional and particularly critical parameter. Using internal references of lower charge state than the target ion systematically yielded overestimated data. Errors measured for quadruply charged molecules were in the range 16–18 ppm when mass calibrants were singly charged ions while accuracy was below 5 ppm when references and target ions were in the same charge state. Magnitude of errors was found to increase with the difference in charge state. This phenomenon arises from the orthogonal acceleration of ions in the TOF analyzer, an interface implemented in all TOF mass spectrometers to accommodate continuous beam ionization sources. Copyright © 2007 John Wiley & Sons, Ltd.