Mass spectral studies on aminocyclitol–aminoglycoside antibiotics

Abstract

The electron impact mass spectral fragmentation patterns of a series of underivatized aminocyclitol–aminoglycoside antibiotics are reported, and their utility in making structural assignments is discussed. The compositions of the fragment ions were confirmed by high resolution mass measurements, and in some cases the origins of the ions were determined by the “direct analysis of daughter ions” technique. The chemical ionization mass spectra of representative compounds of this class are also reported. In general the mass spectra of the underivatized compounds, at least up to the pseudotrisaccharide size, were simpler to interpret and afforded more useful diagnostic information than those of their more volatile permethyl, trimethylsilyl, and per-N-aralkylidene derivatives studied by others.