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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.

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


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.


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

[Available on 2020-03-01]

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