Spectroscopic identification of dyes to probe the effect of anoxic storage

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This thesis aims at estimating the applicability of Desorption ElectroSpray Ionization Mass Spectrometry (DESI-MS) and ESI-MS, Attenuated Total Reflection Fourier Transformed IR and UV-vis spectroscopies to the study of anthraquinone-based dyes in the frame of conservation science, to determine whether anoxic storage would benefit them or not. Such applicability is probed by performing photo-ageing of alizarin in ambient and anoxic atmospheres for ESI-MS, ATR-FTIR and UV-vis, while DESI-MS is used to determine the colorant present on a 17th century Turkish banner. The spectroscopic investigation after ageing showed no differences between ambient and anoxic storage, and a second ageing experiment was undertaken to confirm this result. Again, no major changes were witnessed, except for the influence of water on the ATR spectrum. Meanwhile the determination of the dye applied on the banner was achieved with the identification of dehydrohaematein, coming from logwood.Although the photo-ageing did not allow for degradation mechanisms determination, the techniques employed proved to be relevant. One continuation of this work would be to study thermally-aged alizarin with the same set of spectroscopic techniques. Concerning DESI-MS, it was showed to be a highly relevant tool for conservation science, for it does not require any sample preparation and did not inflict any visible damage to the sample.