title: Matrix-assisted ultraviolet laser-desorption ionization and electrospray-ionization time-of-flight mass spectrometry of sulfated neocarrabiose oligosaccharides.
abstract: Several commercial sulfated neocarrabiose oligosaccharides were analyzed by matrix-assisted ultraviolet laser-desorption ionization time-of-flight mass spectrometry (UV-MALDI-TOF-MS). UV-MALDI-TOF-MS was carried out in the linear and reflectron modes and, as routine, in both the positive- and negative-ion modes. 2,5-Dihydroxybenzoic acid and nor-harmane were used as matrices. In the positive- and negative-ion modes, with both matrices, peaks corresponding to (M+Na)(+) and (M-Na)(-) ions, respectively, were obtained, with only some signals due to glycosidic linkage cleavages (prompt fragmentation). With 2,5-dihydroxybenzoic acid abundant matrix signals were observed; nor-harmane afforded very few matrix signals in both ion modes, but more desulfation (prompt fragmentation) of the compounds occurred. When the desorption/ionization process was highly efficient, the post-source decay (PSD) fragmentation patterns were also investigated; most of the fragments detected derived from glycosidic linkage cleavages. Electrospray-ionization time-of-flight mass spectrometry (ESI-TOF-MS) in the negative-ion mode confirmed, with the observation of the (M-Na)(-) and the multiply charged anions, the identity and the purity of the samples.
mesh_terms: D002240:Carbohydrate Sequence; D002351:Carrageenan / Q000737:chemistry*; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013431:Sulfates / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D009844:Oligosaccharides; D013431:Sulfates; C068279:neocarrabiose; D002351:Carrageenan