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Luncheon Seminar
Day 3, June 24（Tue.） 13:15-13:45
Room A (Maesato West)
- 3A-L-1245-2
The Radicals Strike Back: Enhancing electron-activated dissociation of fatty acids using caged-radical derivatives
(Queensland University of Technology)
oStephen Blanksby
Discrimination of lipid isomers remains a frontier challenge for lipid mass spectrometry and has motivated the development and application of next-generation ion activation technologies. Among these, electron-activated dissociation (EAD) in SCIEX ZenoTOF7600 has shown promise in promoting the fragmentation of carbon-carbon bonds within ionised lipids and thus providing a means to identify sites of unsaturation or methyl chain-branching. Whilst this has been demonstrated for abundant, isomerically resolved lipids, the relatively low abundance of product ions resulting from carbon-carbon bond cleavage makes the unambiguous assignment of lipid structure more challenging for low abundant lipids or in the presence of multiple isomers; a common scenario in biology. EAD mass spectra of thus derivatized fatty acids at modest electron energies (~10 eV) are dominated by [M-I]•+ radical cations and product ions resulting from radical-directed dissociation of the hydrocarbon chain. Initiation of radical ion dissociation in this manner yields increases in the abundance of structurally diagnostic product ions up to 5-fold, enabling the ready discrimination of isomeric unsaturated and branched-chain fatty acids based on EAD spectra acquired on short chromatographic timescales. This enhancement enabled the unambiguous structural assignment of fatty acids in complex lipid extracts including bovine milk powder, human plasma, and bacteria.