A Fragmentation study of di-acidic mycosporine-like amino acids in electrospray and nanospray mass spectrometry

two mycosporine (maas), containing an extra acid function, were analyzed by nanospray and electrospray ionization tandem mass spectrometry. in contrast to the previous studies it is demonstrated that no significant characteristic methyl radical loss occurred in positive mode. the fragmentation pathway in negative mode was also proposed in this work, along with theoretical calculations to characterize the site of protonation.