Before analysis, all serum samples were processed as described, with samples thawed on ice and centrifuged; the supernatant was subjected to further analyses.22 (link) The AbsoluteIDQ® p180 kit assay (Biocrates Life Sciences AG, Innsbruck, Austria) permitted targeted, fully automated quantification of 188 metabolites (142 lipids comprising PC, SM, and acylcarnitines) based on phenylisothiocyanate derivatisation in the presence of internal standards followed by flow injection analysis tandem mass spectrometry using a SCIEX 4000 QTRAP® instrument (SCIEX, Darmstadt, Germany) with electrospray ionisation.
The SCIEX 4000 QTRAP instrument was calibrated periodically after each cleaning cycle, at least once a year, using a chemical standards kit with low/high concentrations of polypropylene glycol polymers (SCIEX, MS Chemical Kit 1, Low-High Conc. PPGs, part number 4406127). The solutions were measured according to the kit instructions and mass calibration and resolution were manually adjusted to meet the specifications of the manufacturer. Measurements were validated by meeting criteria specified by the manufacturer.
The SCIEX 4000 QTRAP instrument was calibrated periodically after each cleaning cycle, at least once a year, using a chemical standards kit with low/high concentrations of polypropylene glycol polymers (SCIEX, MS Chemical Kit 1, Low-High Conc. PPGs, part number 4406127). The solutions were measured according to the kit instructions and mass calibration and resolution were manually adjusted to meet the specifications of the manufacturer. Measurements were validated by meeting criteria specified by the manufacturer.
