Quantitative analysis of saccharides by X-ray photoelectron spectroscopy

Aseries of saccharides, including severalmonohydrates and one amorphous phase, hasbeen investigated by XPS, providing the first database of survey and high-resolution spectra for this class of compounds. Known stoichiometries and XPS-determined elemental compositions agree well. XPS has sufficient precision for distinguishing the stoichiometries of mono-, di-, and polysaccharides. The C 1s chemical shifts of the acetal and alcohol groups are similar for all samples, albeit with slight binding energy increases in the series from mono- to di- and polysaccharides. Increasing X-ray exposure causes a radiation-induced increase of the aliphatic hydrocarbon emission at 285 eV, concomitant with the appearance of a high binding energy C 1s emission peak at 289.1 eV and a decrease in the O 1s/C 1s emission intensity ratio. Formation of aliphatic hydrocarbon groups is proposed to arise from dehydroxylation,while the increase in the 289.1 eV peak can be attributed to double dehydroxylation at the C 1 position or partial oxidation of an alcohol or acetal group. The rate of radiation damage correlates with previously reported rates of thermally induced caramelization. © 2009 John Wiley & Sons, Ltd.