Determination of absorbed organic residues in archaeological pottery using GC-MS

Abstract

The aim of this thesis was to determine organic compounds preserved in the residues of ancient pottery. In particular, I analysed pottery fragments recovered during an excavation of an archaeological site located in Pakistan. The ultimate results of this study will find applications in archaeology, providing insights into the recipes and ingredients utilised by ancient societies. This study was focused on developing a methodological approach that could in the future be applied to a wider range of archaeological samples. The pottery fragments were pre-treated to obtain fine powder that was then extracted by solid-liquid extraction techniques. The extracts were saponified and derivatised before the analysis with gas chromatography (GC) coupled to mass spectrometry (MS). The methodological procedure for the chromatogram analysis allowed obtaining a full list of identifiable compounds for each sample. Identification of the compounds was carried out using the retention time of the compound related to the retention time of internal standard, and then comparing the extracted mass spectra with the mass spectra from existing libraries. Compounds of particular interest considered in this study were those related to potential organic sources deriving from animal fats, plant oils and plant and insect waxes. In addition, comparisons between the organic contents of different samples as well as between the surface and the interior underlying layers were made to elucidate the absorption process of organics in pottery.