Mass spectra of macrolide antibiotics. The utility of the N‐oxide derivatives in enhancing fragmentation of the non‐sugar portion of basic antibiotics

Fragmentation of macrolide antibiotics containing amino sugar moieties in the mass spectrometer provides limited structural information because amino sugar fragmentation dominates the spectrum. Formation of the N‐oxide derivative suppresses these processes and allows the non‐sugar portion to make a more substantial contribution to the spectrum. The N‐oxide may be formed in situ.