CO2 laser enhanced rapid IRMPD spectroscopy for glycan analysis

Infrared Multiple Photon Dissociation (IRMPD) spectroscopy, a combination of Mass Spectrometry (MS) and InfraRed Ion Spectroscopy offers unprecedented performance for molecular structure analysis by adding a spectroscopic dimension to MS workflows. The potential of such approach is particularly relevant for glycomics because carbohydrates of a given mass exist in a large variety of isomers that cannot be resolved by MS alone. We recently reported the development of a rapid and automated IRMPD setup that allowed the acquisition of IR spectra within a few seconds. This rapid IRMPD showed excellent performances in the case of protonated species but also severe limitations when applied to other types of ions. Here we combine a fixed wavelength CO2 laser with a tuneable high repetition rate IR laser to enhance the laser-induced fragmentation. We have applied this method to typical cases encountered in glycan analysis: sodiated species obtained with glycans extracted from natural biological samples, identification of isomers of lithiated hexoses and analysis of acidic negatively charged monosaccharides. This opens new avenues in the development of IRMPD as an analytical tool for glycans.