Figure 3

Positive-ion MS/MS spectra of predicted OHCs and proposed cleavages under collision-induced dissociation. (a) MS/MS spectra of HexCer(t18:1/24:1-OH) and predicted Di-, Tri-, Tetra- and PentaHexCer (H2~5C) in ESI+ under low (+ 30 eV) and high (+ 60 eV) collision energies. (b) Scheme showing proposed fragmentations of the precursor TetraHexCer(t18:1/24:1-OH). Positions of double bonds and hydroxyl groups in ceramide residues are hypothetical.