Study of the attachment of Na⁺ on glucose and on some of its methylated derivatives

Abstract

The mechanism of attachment of Na(+) on glucose, methyl-alpha-D-glucose, methyl-beta-D-glucose, 3-O-methylglucose, tetra-O-methylglucose, and also on galactose and methyl-beta-D-galactose, was studied. For this we measured the ion yields for the complex [sugar-Na(+)] formed by ionisation by matrix-assisted laser desorption/ionisation (MALDI) and ionspray. These data were compared with the relative volatilities and hydrophobicities of the sugars, measured by evaporative light scattering and reversed-phase liquid chromatography, respectively. Some formation enthalpies for the complexes [sugar-Na(+)], starting from the sugar and the cation, were obtained by ab initio calculations. No simple correlations could be observed between the ion yields and the parameters studied, so that the cationisation mechanism of the sugars remains unclear.

Sample preparation effects in matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry of partially depolymerised methyl cellulose

“…Another possible explanation for the appearance of the DS vs. DP plot could be that adduct formation with sodium ions is more favourable when methyl groups are present on the oligomer. It has been shown that the ionisation efficiency in MALDI is increased when methyl groups are introduced on glucose and β ‐cyclodextrins 24,25. The fewer methyl groups, the lower the probability of ionisation, and hence the measured DS is higher for short oligomers containing, on average, fewer substituents.…”

Identification and assay of carbohydrates in olive drupes by cesium attachment electrospray tandem mass spectrometry (ESI‐MS/MS)

“…The assay of chlorinated species suffers, among others, by the drawback of dealing with multi-isotopic species, whereas the disadvantage of sampling sodiated derivatives is represented by the insufficient sensitivity due, in part, to undesirable multicharged adduct ion formation. [26][27][28][29][30][31] Cesium ions have found important analytical applications and Rogatsky et al [32] have reported a simple, sensitive, and rapid LC-MS/MS method perfectly suited for the analysis of carbohydrates. The latter, detected by ESI (+) as cesium adducts, undergo specific formation of cesium cations at m/z 133 after low energy collision-induced dissociations thus allowing Multiple Reaction Monitoring (MRM) (or Selected Reaction Monitoring (SRM)) monitoring of the given analytes in complex mixtures.…”

“…Post hoc comparison was performed using Fischer's least significant difference. [26][27][28][29][30][31] Cesium ions have found important analytical applications and Rogatsky et al [32] have reported a simple, sensitive, and rapid LC-MS/MS method perfectly suited for the analysis of carbohydrates. [25] Higher sensitivity is obtained following the fragmentation of [M + NH 4 ] + adducts of saccharides and glucosides.…”

Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry: Mechanistic Studies and Methods for Improving the Structural Identification of Carbohydrates

“…However, mechanisms about how carbohydrates are alkalized are still unclear. 104) Ion yields of carbohydrates are related to multiple parameters, such as reaction enthalpies for forming adducts with alkali metal ions, volatility, and structural stabilities. 101,105) Owing to the thermally labile nature of carbohydrates, Chen et al reported that low ion yield might be the result of rates of fragmentation and/or desodiation (loss of sodium ions back to its neutral form) being faster than sodiation in the high-temperature ionization environment.…”