Characterization of Ionized Maltooligosaccharides by Sodium Cation in MALDI-TOFMS Depending on the Molecular Size

With such a wide range of structural types, carbohydrate analysis by mass spectrometry can involve a large number of techniques with no single method being ideal for all compounds. Electron impact ionization, for example, is only applicable to the smaller molecules. Matrix-assisted laser desorption/ionization (MALDI), on the other hand, is more versatile because most compounds give signals in their native states. As with other types of mass spectrometry, MALDI can provide valuable information on several aspects of structural analysis, such as the determination of sequence, branching, and linkage. Saccharides are more difficult to analyze than proteins. The hydrophilic nature of oligosaccharides and the lack of a chromophore have presented problems for their analysis, particularly with respect to detection. In addition, the absence of a basic site inhibits protonation in MALDI mass spectrometry. Carbohydrates most often ionize by adduction of metal ions, usually sodium cation, with comparatively low efficiency