Structural elucidation studies of 15-membered azalide macrocycles using H/D exchange and ESI-MS(n.).

A comprehensive study of fragmentation pathways of 15-membered azalide macrocycles using electrospray ionisation with multistage mass spectrometry (ESI-MS(n)) is presented in this work. Hydrogen/deuterium (H/D) exchange experiments and high-resolution mass spectrometry were used to investigate the proposed fragmentation pathways. In addition, the fragmentation patterns of sodium adduct ions M+Na of the macrocycles were also investigated as the presence of an alkali metal interacting with the aglycone ring influences the product-ion spectra.