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Int J Mass Spectrom. 2019 Mar;437:30-37. doi: 10.1016/j.ijms.2018.06.006. Epub 2018 Jun 28.

Multiple TOF/TOF Events in a Single Laser Shot for Multiplexed Lipid Identifications in MALDI Imaging Mass Spectrometry.

Author information

1
Department of Biochemistry, Vanderbilt University, Nashville, TN 37232.
2
Mass Spectrometry Research Center, Vanderbilt University, Nashville, TN 37232.
3
Department of Chemistry, Vanderbilt University, Nashville, TN 37232.
4
Departments of Pharmacology and Medicine, Vanderbilt University, Nashville, TN 37232.

Abstract

Tandem mass spectrometry (MS/MS) is often used to identify lipids in matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS) workflows. The molecular specificity afforded by MS/MS is crucial on MALDI time-of-flight (TOF) platforms that generally lack high resolution accurate mass measurement capabilities. Unfortunately, imaging MS/MS workflows generally only monitor a single precursor ion over the imaged area, limiting the throughput of this methodology. Herein, we demonstrate that multiple TOF/TOF events performed in each laser shot can be used to improve the throughput of imaging MS/MS. This is shown to enable the simultaneous identification of multiple phosphatidylcholine lipids in rat brain tissue. Uniquely, the separation in time achieved for the precursor ions in the TOF-1 region of the instrument is maintained for the fragment ions as they are analyzed in TOF-2, allowing for the differentiation of fragment ions of the exact same m/z derived from different precursor ions (e.g., the m/z 163 fragment ion from precursor ion m/z 772.5 is easily distinguished from the m/z 163 fragment ion from precursor ion m/z 826.5). This multiplexed imaging MS/MS approach allows for the acquisition of complete fragment ion spectra for multiple precursor ions per laser shot.

KEYWORDS:

MALDI; MS/MS; Multiplexed; imaging mass spectrometry; lipid

PMID:
30906202
PMCID:
PMC6424509
[Available on 2020-03-01]
DOI:
10.1016/j.ijms.2018.06.006

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