Scientific context and motivation
The demand for amber has been responsible for the first great impetus to trade which resulted in the spread of civilizations since prehistoric times. The possibility of tracking geological origin of amber is of great importance by allowing more correlations with trade routes and prestige and power of amber artefacts owners. For biologists and geologists, fossil resins are a window into the distant earth’s past, giving important clues about life on earth at the moment of resin formation. Occurrence around the globe covers wide areas and environments (e.g. coals, soil, shale, even the deep-sea sediments). Various analytical methods were developed with the purpose to correlate amber’s chemical composition, spectral and physical properties with its botanical and geological origin. Gas chromatography coupled with mass spectrometry (GC/MS) has been widely and successfully used for identification of volatile compounds (VCs) contained in the fossil resin matrix. GC/MS analysis of amber solvent extractable fractions has evidenced cyclic mono-, bi-, tri- and sesquiterpenoids, and many other VCs. Pyrolysis coupled with MS or GC/MS has been also widely used for characterization of macromolecular insoluble fraction ofamberand even for unmasking amber forgeries. Carlsen et al. have successfully applied multivariate analysis on pyrolysis data, obtaining interesting correlations between amber specimens based on their geographical occurrence. In other studies, VCs have been used as markers for botanical sources or as markers for fossilization processes which could be correlated with amber’s geological origin. In the European region, Baltic amber has been the most studied fossil resin, because of its widest geographical spread and biggest abundance. Stout et al. has recently identified Romanite (Romanian amber) as thermally altered Baltic amber based on systematic study of various samples originated especially from Buzau county. It has been shown that all derivatized VCs from the ether-soluble fraction of Romanite were identified either in the ether-soluble fraction or in the pyrolysis products of the Baltic amber. Feist et al. have studied the thermal behaviour of various fossil resins under inert atmosphere using thermo-gravimetry (TG) and differential thermal analysis (DTA).
The preliminary contribution of the project leader to the proposed research field, consisted in the chemical characterization of fossil resins by means of the combination between thermal desorption as a fast isolation technique for VCs, classic GC–MS analysis, GC–MS data interpretation through AMDIS software and advanced data computing with multivariate analysis techniques used to extract information related with the geological origin of the fossil resins [Virgolici et al. 2010].
The Romanian museums held thousands of adornment items collections, with tens or hundreds of thousands of objects, most of them recovered from funerary contexts. A special category of items is represented by amber objects (generally beads). As regards the archaeological amber items, there is a vast literature, as well as many speculations concerning their origin and commercial routes. Already documented trade routes since prehistoric times and fossil resins geological occurrence in the European region suggest that Romanian amber (also known as Rumanite or Romanite) and Baltic amber (also known as Succinite) are the most probable raw materials used at the manufacture of archaeological amber artefacts found on Romanian territory. The project proposes the development of new analytical methods useful for the chemical characterization of Romanite and its identification in archaeological samples.
[Carlsen 1997] L. Carlsen, A. Feldthus, T. Klarskov, A. Shedrinsky, J. Anal. Appl. Pyrolysis, 1997, 43, 71-81.
[Feist et al. 2007] M. Feist, I. Lamprecht, F. Muller, Thermochim. Acta, 2007, 458 (1-2), 162-170.
[Stout et al. 2000] E.C. Stout, C.W. Beck, K.B. Anderson, Phys. Chem. Miner., 2000, 27 (9), 665-678.
[Virgolici et al. 2010] M. Virgolici, C. Ponta, M. Manea, D. Negut, M. Cutrubinis, I. Moise, R. Suvaila, E. Teodor, C. Sarbu, A. Medvedovici, J. Chrom. A, 2010, 1217 (12), 1977–1987.