Michael, J. A.; Young, R. S. E.; Balez, R.; Jekimovs, L. J.; Marshall, D. L.; Poad, B. L. J.; Mitchell, T. W.; Blanksby, S. J.; Ejsing, C. S.; Ellis, S. R.

We report a workflow based on ozone-induced dissociation for untargeted characterization of hundreds of sn-resolved glycerophospholipid isomers from biological extracts in under 20 minutes, coupled with an automated data analysis pipeline. It provides an order of magnitude increase in the number of sn-isomer pairs identified compared to previous reports, reveals that sn-isomer populations are tightly regulated and significantly different between cell lines, and enables identification of rare lipids containing ultra-long chain monounsaturated acyl chains.