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Determining Energies and Cross Sections of Individual Ions Using Higher-Order Harmonics in Fourier Transform Charge Detection Mass Spectrometry (FT-CDMS)

Determining Energies and Cross Sections of Individual Ions Using Higher-Order Harmonics in... A general method for in situ measurements of the energy of individual ions trapped and weighed using charge detection mass spectrometry (CDMS) is described. Highly charged (> 300 e), individual polyethylene glycol (PEG) ions are trapped and oscillate within an electrostatic trap, producing a time domain signal. A segmented Fourier transform (FT) of this signal yields the temporal evolution of the fundamental and harmonic frequencies of ion motion throughout the 500-ms trap time. The ratio of the fundamental frequency and second harmonic (HAR) depends on the ion energy, which is an essential parameter for measuring ion mass in CDMS. This relationship is calibrated using simulated ion signals, and the calibration is compared to the HAR values measured for PEG ion signals where the ion energy was also determined using an independent method that requires that the ions be highly charged (> 300 e). The mean error of 0.6% between the two measurements indicates that the HAR method is an accurate means of ion energy determination that does not depend on ion size or charge. The HAR is determined dynamically over the entire trapping period, making it possible to observe the change in ion energy that takes place as solvent evaporates from the ion and collisions with background gas occur. This method makes it possible to measure mass changes, either from solvent evaporation or from molecular fragmentation (MSn), as well as the cross sections of ions measured using CDMS. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of The American Society for Mass Spectrometry Springer Journals

Determining Energies and Cross Sections of Individual Ions Using Higher-Order Harmonics in Fourier Transform Charge Detection Mass Spectrometry (FT-CDMS)

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Publisher
Springer Journals
Copyright
Copyright © 2018 by American Society for Mass Spectrometry
Subject
Chemistry; Analytical Chemistry; Biotechnology; Organic Chemistry; Proteomics; Bioinformatics
ISSN
1044-0305
eISSN
1879-1123
DOI
10.1007/s13361-018-1987-x
Publisher site
See Article on Publisher Site

Abstract

A general method for in situ measurements of the energy of individual ions trapped and weighed using charge detection mass spectrometry (CDMS) is described. Highly charged (> 300 e), individual polyethylene glycol (PEG) ions are trapped and oscillate within an electrostatic trap, producing a time domain signal. A segmented Fourier transform (FT) of this signal yields the temporal evolution of the fundamental and harmonic frequencies of ion motion throughout the 500-ms trap time. The ratio of the fundamental frequency and second harmonic (HAR) depends on the ion energy, which is an essential parameter for measuring ion mass in CDMS. This relationship is calibrated using simulated ion signals, and the calibration is compared to the HAR values measured for PEG ion signals where the ion energy was also determined using an independent method that requires that the ions be highly charged (> 300 e). The mean error of 0.6% between the two measurements indicates that the HAR method is an accurate means of ion energy determination that does not depend on ion size or charge. The HAR is determined dynamically over the entire trapping period, making it possible to observe the change in ion energy that takes place as solvent evaporates from the ion and collisions with background gas occur. This method makes it possible to measure mass changes, either from solvent evaporation or from molecular fragmentation (MSn), as well as the cross sections of ions measured using CDMS.

Journal

Journal of The American Society for Mass SpectrometrySpringer Journals

Published: Jun 2, 2018

References