Structural separations of endogenous and exogenous compounds directly from tissue sections by ion mobility – mass spectrometry

Abstract

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) can provide the spatial distribution, relative abundance, and molecular identity of thousands of analytes directly from tissue sections. Due to the complex nature of tissue samples, additional analyte separation is required to increase the specificity of MALDI MS for analytes of interest. Here, the addition of a post-ionization gas-phase structural separation performed by ion mobility (IM) prior to MS is evaluated for its utility to enhance MALDI MS direct tissue analysis by (1) separating analytes of interest from other endogenous compounds, (2) simultaneously analyzing phospholipids and peptides, (3) performing simultaneous fragmentation of all ions, and (4) obtaining analyte gas-phase structural information. Current applications of MALDI IM-MS for tissue analysis as well as future research directions are provided.