Figure 4. Product ion spectrum of m/z 888 obtained directly from the tissue surface (negative ion detection mode).

In the obtained product ion spectrum, the fragment ions derived from polar head group were detected. Peaks derived from sulfonic acid and the dissociation products of galactose were observed in the low m/z region. Above the region of m/z 600, clear unique peak patterns derived from the products of the ceramide moiety were observed.