ID-7-P-3297 Impact of micro-CT and confocal microscopy analyses on amber. A risk assessment study using optical microscopy, FTIR and Raman spectroscopy.

Amber represents an invaluable “time capsule” capturing fossilised residues in 3D. As such, the best material is under considerable demand by researchers. However, the analysis of amber samples and their inclusions using state of the art imaging methodologies including micro-computed-tomography (µ-CT) and confocal microscopy, which are known to yield high quality three-dimensional data, is currently restricted at many institutions. This is because both techniques have the potential to chemically alter the specimen, but the short-term and/or long-term effects of these analytical methodologies are unknown. In the course of this study, the chemical characterization of a number of samples of different types of amber was carried out using Raman and FT-IR spectroscopy, prior to and after exposure to X-rays in a µ-CT scanner and to laser illumination using confocal microscopy. Additional exposure at a synchrotron X-ray source was carried out on a few sub-samples. The results highlighted that both µ-CT and confocal microscopy do not seem to alter the specimens chemically or visually. Hard synchrotron X-rays, however, caused visible discoloration to both amber and copal samples irradiated. Although no discernible difference could be observed between the pre- and post- exposure spectra using Raman spectroscopy, FT-IR spectra showed some minor decrease of the olefin peak at 1645 cm-1 in the Baltic amber sample, and clear oxidation of the succinate esters to succinic acid could be clearly measured in the FT-IR spectra of East African copal.