Field desorption tandem mass spectrometry of anthracycline antibiotics, cosmomycin A, B, A', B', C and D.

Field desorption mass spectrometry was applied to a series of underivatized anthracycline, cosmomycins, to obtain fragment ions which were mass analysed using the linked scan technique without using collision activated dissociation. The daughter spectra of the various protonated compounds contain sugar sequence information which is in the mass spectra. The mass spectrometric data make it clear that field desorption tandem mass spectrometry can become a valuable additional technique for the structural analysis of anthracyclines.