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Data mining algorithms have been used to analyze the infrared multiple photon dissociation (IRMPD) patterns of gas-phase lithiated disaccharide isomers irradiated with either a line-tunable CO(2) laser or a free electron laser (FEL). The IR fragmentation patterns over the wavelength range of 9.2-10.6 μm have been shown in earlier work to correlate uniquely with the asymmetry at the anomeric carbon in each disaccharide. Application of data mining approaches for data analysis allowed unambiguous determination of the anomeric carbon configurations for each disaccharide isomer pair using fragmentation data at a single wavelength. In addition, the linkage positions were easily assigned. This combination of wavelength-selective IRMPD and data mining offers a powerful and convenient tool for differentiation of structurally closely related isomers, including those of gas-phase carbohydrate complexes.

Fragmentation of lithium cation-attached alpha- and beta-O-methyl-glucopyranoside precursor ions, formed by electrospray ionization (ESI) and trapped in a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer, was produced by infrared radiation from a tunable CO(2) laser. Irradiation over the wavelength range from 9.20 to 10.80 microm yielded unique fragmentation patterns that were a function of both product ion mass and laser wavelength. Comparison of the relative percent abundances of fragment ions for the two anomers revealed statistically significant differences for wavelengths between 9.20 and 9.70 microm at the 95% confidence level. On the basis of these results, differentiation of anomeric configurations of monosaccharides within oligosaccharides may be possible to address by wavelength-selective infrared multiple-photon dissociation (IRMPD).