Fig. 2: Optimization of elevated energy HCD of sodiated precursors to support structural elucidation of oxidized neutral lipids.

Utility of tandem mass spectra to provide structure-relevant fragment ions was compared for protonated (gray), ammoniated (blue) and sodiated (green) oxCE precursor ions (a). Considering larger numbers of structure-relevant fragment ions obtained by HCD of sodiated oxCE precursors, the collision energy was optimized to enhance fragment ions formation (b). Elevated energy stepped HCD MS2 experiments using sodiated precursors were shown to provide highly informative spectra, exemplified here for CE(18:2<OOH{13}>) (c) and TG(16:0_16:0_18:2<OOH{13}>) (d).