| dc.description |
The bound water content for isomeric disaccharide based glycolipids is determined by deuterium NMR spectroscopy and DSC. The NMR investigation faced obstacles due to pseudo-isotropic spectra for β-glycoside based on β-1,4-linked disaccharides, i.e. dodecyl β lactoside and dodecyl β-cellobioside. Only at temperatures significantly exceeding 100â °C typical powder spectra could be observed. The determined bound water content for the lactoside is with only two molecules water per surfactant surprisingly small. A slightly higher value was determined for a branched β-maltoside. While this investigation did not require high temperature, the spectra were poorly resolved and quadrupole splittings had to be estimated based on the half-peak width of a single broad signal. The low bound water contents rise questions on the reliability of the D-NMR method for these compounds, or more generically in case of high temperature requirements and poorly resolved powder spectra. In order to evaluate the data, a DSC investigation based on the freezing and melting of water was targeted. A model study on dodecyl β-maltoside indicates a reasonable agreement with previous D-NMR spectroscopic investigations on the same compound. This result indicates that DSC may be used to evaluate the low bound water contents determined by D-NMR. |
