Mass recalibration for desorption electrospray ionization mass spectrometry imaging using endogenous reference ions

Abstract

Mass spectrometry imaging (MSI) data often consist of tens of thousands of mass spectra collected from a sample surface. During the time necessary to perform a single acquisition, it is likely that uncontrollable factors alter the validity of the initial mass calibration of the instrument, resulting in mass errors of magnitude significantly larger than their nominal values. This phenomenon has a two-fold detrimental effect: a) it reduces the ability to interpret the results based on the observed signals, b) it can affect the quality of the observed signal spatial distributions. Here, we present a post-acquisition computational method capable of reducing the observed mass drift in biological samples, exploiting the presence of typical molecules with a known mass-to-charge ratio. The method is tested on time-of-flight and Orbitrap mass spectrometry analyzers interfaced to a desorption electrospray ionization (DESI) source.

Mass spectrometry imaging highlights dynamic patterns of lipid co‐expression with Aβ plaques in mouse and human brains

“…Raw DESI MSI data were pre‐processed using a pipeline reported by Inglese et al. (Inglese et al., 2021). Briefly, a Kneedle (Satopaa et al., 2011) algorithm‐based modification of the method of Zhurov et al.…”

Advances in mass spectrometry imaging for spatial cancer metabolomics

“…Chemical background ions can also be used for calibration in MALDI MSI (Boskamp et al, 2020). For DESI MSI, the calibrants are usually added to the spray solvent and sprayed directly from the ESI nozzle (Inglese et al, 2021). Normally, external and internal calibration are combined for better results.…”