Direct Ion Imaging Approach for Investigation of Ion Dynamics in Multipole Ion Guides

Sarfaraz U. A. H. Syed, Simon Maher, Gert B. Eijkel, Shane R. Ellis, Fred Jjunju, Stephen Taylor, Ron M. A. Heeren*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


A key requirement of electrospray ionization (ESI) and other techniques facilitating ionization at elevated pressures is the efficient transport of free gas-phase ions into the high vacuum region of the mass spectrometer. Radio frequency (RE) multipole ion guides that allow for collisional cooling are one of the most popular means of achieving this. However, their performance is highly dependent on several experimental factors, including pressure and various electrode potentials along the ion path. To experimentally visualize these effects, we have employed a position-sensitive detector at the exit of a quadrupole mass spectrometer (QMS) instrument operated in RF only mode that employs an RE only octopole as a collisional cooling ion guide. This allows the spatial distribution of the ions, and its,dependence on experimentally determined conditions, to be directly visualized at the exit of the quadrupole. This investigation provides a detailed insight into the ion dynamics occurring inside multipole ion guides. This knowledge can directly be applied to instrument development and to improve the ion transmission efficiency and, thus, sensitivity: Numerical simulations Using custom-developed trajectory simulation software are compared and contrasted with the :experimental observations.
Original languageEnglish
Pages (from-to)3714-3720
JournalAnalytical Chemistry
Issue number7
Publication statusPublished - 7 Apr 2015

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