Fig. 3.

EI-mass spectra of the alditol acetate derivative of GlcN (a) and GlcN3N (b) found in Z. profunda SM-A87 lipid A. On the right, the fragmentation pattern observable for both residues is reported. Several daughter ions caused by elimination of acetic acid (− 60) or an N-acetyl group (− 42) from C3-C6 and C1-C2 fragment ions were observed, alongside with typical ions at m/z 156, 155, 114, and 113 that were matched with daughter ions generated from the C1-C3 fragment