12 Scopus citations


1-O-acylceramide is a new class of epidermal ceramide (Cer) found in humans and mice. Here, we report an ESI linear ion-trap (LIT) multiple-stage MS (MSn) approach with high resolution toward structural characterization of this lipid family isolated from mice. Molecular species desorbed as the [M + H]+ ions were subjected to LIT MS2 to yield predominately the [M + H-H2O]+ ions, followed by MS3 to cleave the 1-O-acyl residue to yield the [M + H-H2O-(1-O-FA)]+ ions. The structures of the N-acyl chain and longchain base (LCB) of the molecule were determined by MS4 on [M + H-H2O-(1-O-FA)]+ ions that yielded multiple sets of specific ions. Using this approach, isomers varied in the 1-O-acyl (from 14:0-to 30:0-O-acyl) and N-acyl chains (from 14:0-to 34:1-N-acyl) with 18:1-sphingosine as the major LCB were found for the entire family. Minor isomers consisting of 16:1-, 17:1-, 18:2-, and 19:1-sphingosine LCBs with odd fatty acyl chain or with monounsaturated N-or O-fatty acyl substituents were also identified. An estimation of more than 700 1-O-acylceramide species, largely isobaric isomers, are present, underscoring the complexity of this Cer family.

Original languageEnglish
Pages (from-to)772-782
Number of pages11
JournalJournal of lipid research
Issue number4
StatePublished - 2017


  • Electrospray ionization
  • High-resolution mass spectrometry
  • Higher collision energy dissociation
  • Lipidomics
  • Multiple-stage tandem mass spectrometry
  • Skin ceramide
  • Sphingolipid


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