title: Mass measurement errors caused by 'local" frequency perturbations in FTICR mass spectrometry.
abstract: One of the key qualities of mass spectrometric measurements for biomolecules is the mass measurement accuracy (MMA) obtained. FTICR presently provides the highest MMA over a broad m/z range. However, due to space charge effects, the achievable MMA crucially depends on the number of ions trapped in the ICR cell for a measurement. Thus, beyond some point, as the effective sensitivity and dynamic range of a measurement increase, MMA tends to decrease. While analyzing deviations from the commonly used calibration law in FTICR we have found systematic errors which are not accounted for by a "global" space charge correction approach. The analysis of these errors and their dependence on charge population and post-excite radius have led us to conclude that each ion cloud experiences a different interaction with other ion clouds. We propose a novel calibration function which is shown to provide an improvement in MMA for all the spectra studied.
authors.affiliation: Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland, Washington (99352, USA.
authors.forename: Christophe
authors.initials: C
authors.lastname: Masselon
authors.forename: Aleksey V
authors.initials: AV
authors.lastname: Tolmachev
authors.forename: Gordon A
authors.initials: GA
authors.lastname: Anderson
authors.forename: Richard
authors.initials: R
authors.lastname: Harkewicz
authors.forename: Richard D
authors.initials: RD
authors.lastname: Smith
mesh_terms: D002627:Chemistry, Physical / Q000379:methods; D005583:Fourier Analysis; D013058:Mass Spectrometry / Q000379:methods* / Q000592:standards