Differentiation of glucose-containing disaccharides by infrared multiple photon dissociation with a tunable CO2 laser and Fourier transform ion cyclotron resonance mass spectrometry

Lithiated glucose-containing disaccharides with various linkages and anomeric configurations, formed by electrospray ionization (ESI) and trapped in a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer, were fragmented by infrared radiation from a tunable CO2 laser. Irradiation over the wavelength range from 9.2 to 9.7 mu m gave unique fragmentation patterns for each of the disaccharides. These fragmentation patterns can be used to easily determine the monosaccharide linkage position for each disaccharide. Once the linkage is determined, irradiation of the precursor ion (m/z 349) to produce a specific ratio of peak height for a particular fragment ion to that of the precursor ion is shown to yield unique ratio values that can be used to identify the different anomers of the same linkage at the 95% confidence level. (C) 2010 Elsevier B.V. All rights reserved.