Fig. 5

Hypothesized neutral structures of the ions m/z 88 low mass positive (4A), m/z 101 low mass positive (4B), m/z 116 low and normal mass positive (4C), m/z 158 normal mass positive (4D), m/z 74 low mass negative (4E), m/z 115 norm mass negative (4F). The fragmentation mass spectra for these ions are reported in the Additional file 1