LC-MS analysis of human epidermal extracts for linoleate and
linoleate triol-containing ceramides.
A, total ion current profile
(m/z 950–1350) of LC-MS
analysis of a MeOH/CHCl3 extract of human epidermis using an
Advantage 5-μm silica column (250 × 4.6 mm) run with gradient
elution of hexane/IPA/HAc (95:5:0.1) to hexane/IPA/HAc (75:25:0.1) over
30 min using a Waters Alliance 2690 HPLC system coupled to a TSQ Vantage
mass spectrometer (Thermo Scientific). The arrow at 20
min marks the retention time of putative linoleate triol-containing
ceramides. B, extracted ion chromatogram of the
molecular species eluting at 20 min. C, selected ion
monitoring of C32 ceramide species to the respective daughter ions of
m/z 279 (linoleate) and m/z 329
(linoleate triols), confirming identification of EOS
(m/z 1075–279 [M + Cl]-), EOS-triol
(m/z 1149–329 [M − H +
CH3CO2H]-), and Glu-EOS (m/z
1237–279 [M + Cl]-).