GC And HPLC Separation Techniques for the Elucidation of Aged Lipid Compounds in Archaeological Context

Analytical investigations of organic residues in archaeological pottery are fundamental to unveil crucial hints about the daily life of ancient societies. The attention of analysts is particularly focused on lipid compounds, due to their hydrophobicity that makes them particularly durable over time [1]. However, most of the lipids are featured by reactive functional groups along the molecular structures that may lead to their alteration in the archaeological site. The in-lab simulation of alteration processes such as thermal decomposition, oxidation or hydrolysis of lipids can provide key elements to better interpret the origin of animal fats and vegetable oils partially or totally altered over the time [2]. This research is focused on the in-lab ageing of lipid matters in order to simulate the natural degradation occurring in archaeological pottery. In detail, pure triglyceride (TAG) standards such as triolein (OOO) and trilinolein (LLL) were kept in an oven at 120°C for three weeks. In addition, an extra-virgin olive oil, traditionally used in Mediterranean ancient societies, was subjected to the thermo-oxidative treatment. The degradation of the intact lipids was monitored by using non-aqueous reversed phase HPLC coupled to APCI mass spectrometry. High and medium volatility components, including short-chain fatty acids (SCFA), aldehydes, ketones, lactones and esters, were extracted by using headspace SPME and separated by GC-MS analysis. Low-volatility and polar compounds, such as medium- and long-chain fatty acids and (α,ω)-dicarboxylic acids, were converted into trimethylsilyl ethers (TMS) derivatives and analysed by GC-MS. References [1] Stern, B.; Heron, C.; Tellefsen, T.; Serpico, M., New investigations into the Uluburun resin cargo. J. Archaeol. Sci. 2008, 35, (8), 2188-2203. [2] Irto, A.; Micalizzi, G.; Bretti, C.; Chiaia, V.; Mondello, L.; Cardiano, P. Lipids in Archaeological Pottery: A Review on Their Sampling and Extraction Techniques. Molecules. 2022, 27, 3451.