Fig. 5

Positive MS spectrum (a), positive MS/MS spectrum (b) and negative MS/MS spectrum (c). The positive MS spectrum provides the mass of the precursor ion [M+H]⁺ = 690.5099 Da and its isotopic abundance pattern. The prominent ion in the positive MS/MS spectrum corresponds to the neutral loss of the phosphoethanolamine head group. The negative MS/MS spectrum shows the molecular ion [M−H]⁻ as well as a pair of ions corresponding to the (16:0) and (16:1) side chains.