Maldi hdms synapt g2 si mass spectrometer

For
further confirmation of molecular identity,
a Waters MALDI HDMS Synapt G2-Si mass spectrometer (Waters Corporation,
Manchester, UK) equipped with an Nd:YAG laser was used to perform
ion mobility separation (IMS) and tandem mass spectrometry (MS/MS)
measurements. The instrument was calibrated using red phosphorus prior
to analysis. MS/MS was performed on consecutive tissue sections, the
laser power was 150 arbitrary units (1 kHz), and the ions of interest
were fragmented by collision induced dissociation (CID) in the trap
cell with an isolation window of approximately 3 Da. For ion mobility,
the IMS wave velocity was 900 m/s and the wave height was 40 V. For
presentation purposes, mass spectra from the MassLynx version 4.1
software (Waters Corporation) were exported in the form of text files
and imported into mMass, open-source software used for mass spectral
processing.^{14 (link)} The MS/MS spectra from the
commercial bile acid standards and tissue sections were compared to
those in the literature or databases such as lipid maps (www.lipidmaps.org) and the ALEX123
lipid calculator (www.alex123.info). The fragment ions observed in each MS/MS spectrum were assigned
based on the recently proposed nomenclature for lipids.^{15 (link)}