Gas-phase ion/ion reactions in linear ion trap mass spectrometers: Method development and application to biomolecule analysis

Xiaorong Liang, Purdue University

Abstract

Gas-phase ion/ion reactions are being explored for their analytical utility in the analysis of biomolecules. Ion/ion reactions implemented in a linear ion trap (LIT) are attractive because LITs hold significant advantages over three-dimensional (3-D) quadrupole ion traps in terms of dynamic range and the efficiency with which they can be coupled with ion sources, detectors, and other mass analyzers. However, currently on a commercial mass spectrometer there is no supply of more than two ionization sources or auxiliary RF trapping potential on the containment lenses or end segments of a LIT. Thus, simultaneous trapping of oppositely charged ions can not be achieved, which is essential for ion/ion reactions in electrondynamic ion traps. As a result of this thesis work, new ionization sources and methods to implement ion/ion reactions in LITs have been developed to enable ion/ion reaction studies in LITs for biomolecule analysis. The first part of this dissertation is focused on the new ionization sources for ion/ion electron-transfer dissociation and proton-transfer reactions on a hybrid triple quadrupole/LIT instrument. The combination of alternately pulsed nano-electrospray ionization (nanoESI)/atmospheric pressure chemical ionization (APCI) sources is well suited to implementation of experiments involving multiply charged ions in reaction with singly charged ions of opposite polarity. A pulsed triple ionization source was further developed to generate different types of ions for sequential ion/ion reaction experiments. In the second part, two transmission mode methods were developed for facile implementation of ion/ion reactions in a high pressure LIT on commercial ion trap mass spectrometers. Two useful ion/ion reactions, electron-transfer dissociation and proton-transfer reactions, for protein/peptide analysis employing mutual storage mode experiments were demonstrated here with the hybrid triple quadruple/LIT instrument. Finally, ion/ion electron-transfer dissociation of doubly sodiated glycerophosphocholine lipids in a LIT was investigated.

Degree

Ph.D.

Advisors

McLuckey, Purdue University.

Subject Area

Analytical chemistry

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