Ozone-induced dissociation: elucidation of double bond position within mass-selected lipid ions

Anal Chem. 2008 Jan 1;80(1):303-11. doi: 10.1021/ac7017684. Epub 2007 Dec 7.


Ions formed from lipids during electrospray ionization of crude lipid extracts have been mass-selected within a quadrupole linear ion trap mass spectrometer and allowed to react with ozone vapor. Gas-phase ion-molecule reactions between unsaturated lipid ions and ozone are found to yield two primary product ions for each carbon-carbon double bond within the molecule. The mass-to-charge ratios of these chemically induced fragments are diagnostic of the position of unsaturation within the precursor ion. This novel analytical technique, dubbed ozone-induced dissociation (OzID), can be applied both in series and in parallel with conventional collision-induced dissociation (CID) to provide near-complete structural assignment of unknown lipids within complex mixtures without prior fractionation or derivatization. In this study, OzID is applied to a suite of complex lipid extracts from sources including human lens, bovine kidney, and commercial olive oil, thus demonstrating the technique to be applicable to a broad range of lipid classes including both neutral and acidic glycerophospholipids, sphingomyelins, and triacylglycerols. Gas-phase ozonolysis reactions are also observed with different types of precursor ions including [M+H]+, [M+Li]+, [M+Na]+, and [M-H]-: in each case yielding fragmentation data that allow double bond position to be unambiguously assigned. Within the human lens lipid extract, three sphingomyelin regioisomers, namely SM(d18:0/15Z-24:1), SM(d18:0/17Z-24:1), and SM(d18:0/19Z-24:1), and a novel phosphatidylethanolamine alkyl ether, GPEtn(11Z-18:1e/9Z-18:1), are identified using a combination of CID and OzID. These discoveries demonstrate that lipid identification based on CID alone belies the natural structural diversity in lipid biochemistry and illustrate the potential of OzID as a complementary approach within automated, high-throughput lipid analysis protocols.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anions / chemistry*
  • Cations / chemistry*
  • Cattle
  • Glycerophospholipids / analysis
  • Glycerophospholipids / chemistry
  • Humans
  • Kidney / chemistry
  • Kinetics
  • Lens, Crystalline / chemistry
  • Lipids / analysis
  • Lipids / chemistry*
  • Ozone / chemistry*
  • Phosphatidylcholines / analysis
  • Phosphatidylcholines / chemistry
  • Spectrometry, Mass, Electrospray Ionization*
  • Triglycerides / analysis
  • Volatilization


  • Anions
  • Cations
  • Glycerophospholipids
  • Lipids
  • Phosphatidylcholines
  • Triglycerides
  • Ozone