Periodate oxidation of cyclosophoraoses: a quantitative analysis of the reaction products by ionspray mass spectrometry

The reaction products from the periodate oxidation of cyclosophoraoses, having glucose residues ranging from 17 to 21, were studied by means of ionspray mass spectrometry. Three different samples exhibiting different degrees of oxidation (∼30, ∼65 and ∼85%) were investigated. In order to avoid both insolubility and complex spectra due to water adduct formation, the oxidised cyclosophoraoses were exhaustively reduced in order to convert the aldehydic functions into hydroxyl groups. The individual ions comprising the mass spectral envelope were assigned by taking into account the coexistence of different degrees of oxidation for each cyclosophoraose member. The distribution of variable degrees of oxidation was studied in terms of the statistical Poisson distribution and the experimental data were fitted with the expected theoretical distributions. Detection of unfragmented ions coupled with both high m/z resolution and mathematical modelling allowed the quantitative definition of the distribution of the degree of oxidation for each cyclosophoraose ring size. This information makes possible the use of specific oxidised derivatives as building blocks for complex molecular systems.