Resins, archaeological analysis

The results show that DE-MS alone provides evidence of the presence of the most abundant components in samples. On account of the relatively greater difficulty in the interpretation of DE-MS mass spectra, the use of multivariate analysis by principal component analysis (PCA) of DE-MS mass spectral data was used to rapidly differentiate triterpene resinous materials and to compare reference samples with archaeological ones. This method classifies the spectra and indicates the level of similarity of the samples. The output is a two- or three-dimensional scatter plot in which the geometric distances among the various points, representing the samples, reflect the differences in the distribution of ion peaks in the mass spectra, which in turn point to differences in chemical composition of... 

SPME/GC/MS is an efficient technique to reveal the presence of resinic substances in archaeological samples. Indeed, volatile terpenes are still present in very old archaeological samples (4000 years old), particularly in the case of compact matrixes, and can be trapped by the SPME fibre. In comparison with methylene chloride extraction, SPME is very specific and allows the direct analysis of the volatile terpenes content in complex mixtures including oils, fats or waxes. For this reason, headspace SPME is the first method to use when analysing an archaeological sample it will either allow the identification of the resin or indicate further sample treatment in order to detect characteristic triterpenes. The method is not really nondestructive because it uses a little of the sample but the same sample can be used for several SPME extractions and then for other chemical treatments. 

Heron, C. and Pollard, A.M. (1988). The analysis of natural resinous materials from Roman amphoras. In Science and Archaeology, Glasgow 1987, ed. Slater, E.A. and Tate, J.O., British Series 196, British Archaeological Reports, Oxford, pp. 429-447. 

One of the most interesting classes of compounds, from the point of view of their importance in the field of art and archaeology, is natural resins. The past 15 years have brought some remarkable successes in this area of analysis and at the same time revealed some very fundamental difficulties that are not so easily overcome. 

The subject of another investigation in the nature of archaeological amber samples (pendants found in the upper reaches of the Western Dvina River) was the fact that a chunk of resinous material found by local residents in the same location was a candidate for the raw material used to make these pendants. Py-GC/MS analysis revealed that all the pendants were made of Baltic amber, and the raw material represented a totally different class of organic compounds — natural gums. Figure 6.10 shows two pyrograms (A for the Baltic amber with a strong peak of succinic anhydride and B for the natural gum with a very characteristic peak of furfural). 

Many organic natural substances that can be found in association with archaeological artifacts under Py produce low volatile molecules that contain polar func-tionaUties, which are not efficiently separated by GC. This is the case with fatty acids and di- and triterpenoid adds produced in the Py of Upids and natural resins. Over the last few years, the most common approach to overcome problems related to GC analysis of low volatile polar Py products is to use thermaUy assisted reactions. Py of the sample in the presence of a suitable derivatization reagent, which transforms the polar functionalities of the Py products into less polar moieties, improves the analytical performance and detection Umits. Thermally assisted hydrolysis and methy-lation (THM) based on quaternary alkylammonium... 

Samples of a visible surface residual material has been scraped from the surface of archaeological potsherds for analysis. The location and physical appearance of the resin on the sherds varied a great deal. Although material is available from several sites only two. Spirit Cave and Noen U-Loke, both in Thailand are discussed here since samples from these sites have been both analysed to determine their chemical composition and submitted for radiocarbon dating. 

Provision of information about archaeological and historical trade routes from the spectroscopic analysis of dyes, pigments, and resins... 

Mr. Aoki tried to conserve excavated archaeological art objects. For instance, an iron sword is at first desalted by the Soxhlet extraction method. After that it is treated with an organofunctional silane followed by impregnation with acrylic resin emulsions the analysis of polymeric material used for these preservations is very important, as in general, polymeric materials are important for the preservation of the art objects. 

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