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Charge Distribution between Different Classes of Glycerophospolipids in MALDI-MS Imaging
journal contribution
posted on 2020-03-18, 16:42 authored by Marcel
S. Boskamp, Jens SoltwischMatrix-assisted laser
desorption ionization mass spectrometry imaging
(MALDI-MSI) is widely used to visualize and analyze the distribution
of membrane lipids in an increasingly large number of applications.
In this context, different lipoforms of glycerophospholipids (GPLs)
are among the prime targets of interest. For this group of analytes,
however, ion suppression effects have been described to strongly favor
the detection of certain GPL classes over others, thereby hampering
the analysis of suppressed species and greatly restraining quantitative
analysis. These effects are generally attributed to the distribution
of available charge carriers during the MALDI process. Here, we present
a systematic investigation of charge distribution between different
classes of GPL under MALDI-MSI conditions. For this, we constructed
arrays of artificial tissues with different formulated lipid composition
that contained predefined amounts of only two specific GPL classes
and analyzed them with MALDI-MSI in positive- and negative-ion modes.
Next to a characterization of expected ion suppression effects, analysis
of these binary systems revealed yet undescribed signal intensity
enhancement for the combinations of certain GPL classes. Furthermore,
the comprehensive data allowed us to compile a hierarchy of charge
affinities for the investigated GPL classes in both polarities. Additional
experiments revealed that laser post-ionization (MALDI-2) has great
potential to overwrite changes in signal intensity caused by charge
distribution among different GPL classes observed in standard MALDI-MSI.