Shotgun Approach for Quantitative Imaging of Phospholipids
Using Nanospray Desorption Electrospray Ionization Mass Spectrometry
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Abstract
Mass spectrometry imaging (MSI) has
been extensively used for determining
spatial distributions of molecules in biological samples, and there
is increasing interest in using MSI for quantification. Nanospray
desorption electrospray ionization (nano-DESI) is an ambient MSI technique
where a solvent is used for localized extraction of molecules followed
by nanoelectrospray ionization. Doping the nano-DESI solvent with
carefully selected standards enables online quantification during
MSI experiments. In this proof-of-principle study, we demonstrate
that
this quantification approach can be extended to provide shotgun-like
quantification of phospholipids in thin brain tissue sections. Specifically,
two phosphatidylcholine (PC) standards were added to the nano-DESI
solvent for simultaneous imaging and quantification of 22 endogenous
PC species observed in nano-DESI MSI. Furthermore, by combining the
quantitative data obtained in the individual pixels, we demonstrate
quantification of these PC species in seven different regions of a
rat brain tissue section