Photodissociation with visible light (VisPD) has been applied to chromophore labelled oligosaccharide ions produced by electrospray in a Fourier-Transform Ion Cyclotron Resonance (FT-ICR) mass spectrometer. As chromophores different aromatic dyes, such as Rhodamine 110, have been attached to maltopentaose, lacto-N-fucopentaose I (LNFP I) and lacto-N-fucopentaose II (LNFP II). Comparing VisPD and CID more fragments can be observed in the VisPD-spectra. Fragmentation is highly influenced by the charge state and adduct ion species of the carbohydrates. Protonated species [M+H]+ procuce fragments that include the reducing end of the sugars and the label. Mainly glycosidic cleavages are monitored (basically Ytype). In the negative ion mode only fragments without the label can be observed. In addition to glycosidic cleavages (B-, C-, Y- and Z-type), cross ring cleavages (A-type) occur. Under addition of alkali salts the formation of different adduct ions can be observed (e.g. [M+Na]~+ and [M+H+K]~(2+)) and were fragmented with VisPD as well.
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