Mass Spectrometry Imaging of Lipids Using MALDI Coupled with Plasma-Based Post-Ionization on a Trapped Ion Mobility Mass Spectrometer

Anal Chem. 2022 Dec 20;94(50):17494-17503. doi: 10.1021/acs.analchem.2c03745. Epub 2022 Dec 6.

Abstract

Here we report the development and optimization of a mass spectrometry imaging (MSI) platform that combines an atmospheric-pressure matrix-assisted laser desorption/ionization platform with plasma postionization (AP-MALDI-PPI) and trapped ion mobility spectrometry (TIMS). We discuss optimal parameters for operating the source, characterize the behavior of a variety of lipid classes in positive- and negative-ion modes, and explore the capabilities for lipid imaging using murine brain tissue. The instrument generates high signal-to-noise for numerous lipid species, with mass spectra sharing many similarities to those obtained using laser postionization (MALDI-2). The system is especially well suited for detecting lipids such as phosphatidylethanolamine (PE), as well as numerous sphingolipid classes and glycerolipids. For the first time, the coupling of plasma-based postionization with ion mobility is presented, and we show the value of ion mobility for the resolution and identification of species within rich spectra that contain numerous isobaric/isomeric signals that are not resolved in the m/z dimension alone, including isomeric PE and demethylated phosphatidylcholine lipids produced by in-source fragmentation. The reported instrument provides a powerful and user-friendly approach for MSI of lipids.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain
  • Diagnostic Imaging*
  • Mice
  • Phosphatidylcholines
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods
  • Sphingolipids*

Substances

  • Sphingolipids
  • Phosphatidylcholines