Abstract

Abstract

Chemical analysis of organic materials in archaeological contexts is essential for studying ancient techniques, understanding degradation phenomena, and implementing scientifically informed preservation strategies. The characterisation of organic historic and archaeological samples can be achieved through is generally based on quantitative analyses by high performance liquid chromatography (HPLC) and gas chromatography (GC), which provide an excellent separation and resolution of complex mixtures, as well as low detection limits. Both qualitative and quantitative analyses by GC or HPLC are limited to those analytes that can be made soluble or volatile with adequate sample pre-treatments, including extraction, hydrolysis, and derivatization. However, most organic materials in historical and archaeological objects are indeed macromolecular. In some cases, they are macromolecular materials by nature, such as proteins, lignocellulosic polymers, plant gums or fossils. Other materials undergo polymerisation upon curing, such as natural resins, tar and charred materials. Cross-linking also occurs in most materials, as an effect of the exposure to light and air during ageing. In the end, most organic materials in the archaeological world contain a major fraction that is insoluble and chemically non-hydrolysable. GC or HPLC alone do not give access to this important fraction, thus limiting the analysis of a small, and possibly not fully representative, fraction of the samples. Pyrolysis, which thermally decomposes solid samples without pre-treatment, is particularly valuable for studying insoluble, chemically stable materials in archaeological artefacts. While Py-GC/MS does not provide fully quantitative data, it offers semi-quantitative insights, making it essential for analysing organic remnants like wood and textiles. Advances such as evolved gas analysis (EGA-MS) have further enhanced the analysis of complex archaeological materials, providing new insights into ancient organic substances. This talk will focus on the application of analytical pyrolysis and complementary techniques in the study of various materials, with a particular emphasis on historical textiles and archaeological wood and charcoal. The presentation will highlight how these analytical methods have been employed to investigate the degradation processes and chemical composition of these materials. Additionally, methodological challenges encountered during the research process will be addressed, discussing key mistakes and the insights gained from them.

Bio

Deborah Roversi is a PhD candidate at University of York and University Côte d’Azur, specialising in the study of archaeological wood and charred materials. Her research focuses on understanding degradation mechanisms using advanced analytical techniques, such as FTIR , EGA-MS, Py-GC/MS, and XRD , to investigate chemical and structural changes in ancient artefacts.

Please join us in-person in the McDonald Institute seminar room or join online.

https://teams.microsoft.com/l/meetup-join/19%3ameeting_ZDc2MDk1ZGQtNmNkZC00M2U2LTliYjMtN2EyZWE0MDI5ZTAz%40thread.v2/0?context=%7b%22Tid%22%3a%2249a50445-bdfa-4b79-ade3-547b4f3986e9%22%2c%22Oid%22%3a%227c42dde3-f200-49ed-9a81-5aa7e67f945e%22%7d