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Identifier

000436187

Title

Biomolecular residue analysis in archaeological potsherds by means of UV-vis absorption and fluorescence spectroscopy

Alternative Title

Μελέτη βιομοριακών δεικτών με φασματοσκοπία απορρόφησης υπεριώδους-ορατού και φθορισμού για τον χαρακτηρισμό οργανικών καταλοίπων σε αρχαιολογικά κεραμικά

Author

Ιντζέ, Αντωνία Ι.

Thesis advisor

Άγγλος, Δημήτριος

Reviewer

Σπύρος, Απόστολος
Παυλίδης, Ιωάννης

Abstract

Bio-organic residue analysis of archaeological artefacts sheds light on human activities and surviving practices during historic and prehistoric times using powerful analytical methodologies based mainly on chromatographic techniques coupled with mass spectrometry. In the context of archaeo-residue analysis, spectroscopic methods are advantageous since they enable fast-screening of samples via prompt detection of biomarkers and, thus, expedite the further study of promising samples by high-end analytical tools. The present master’s thesis focuses on the study of archaeological potsherds originating from the Minoan civilization by means of UV-vis absorption and fluorescence spectroscopy with the aim of developing efficient detection and characterization methodologies of biomarker compounds. Analyses of samples are conducted in solutions deriving from solvent treatment of the sherds. The analytical methodology relies at first on recording UV-vis absorption spectra and then on recording emission and excitation fluorescence spectra in extracted solutions originating from three parts of the potsherds: inner, outer, and inner soil crust. Detailed examination of fluorescent data allows the construction of three-dimensional fluorescence excitation-emission maps for each sample and subsequently the comparison of the fluorescent profiles of unknown samples with those of standard solutions. Standard aqueous solutions of phenolic acids (ferulic acid, gallic acid, caffeic acid, syringic acid, and vanillin) were prepared and studied as they comprise an important class of intrinsic fluorophores in wine that is known to preserve over archaeological timescales. Phenolic compounds were proposed to serve as wine markers, while secondary oxidation products of unsaturated lipids were suggested to compose oil markers. Based on the identification of such molecular indicators it is proposed that a Minoan amphora has been used to stored oil and wine, while two Minoan cylinder vessels were utilised as oil containers. Fluorophores in archaeological samples were also quantified, assuming that they were represented by phenolic acid compounds. To this end, a comparative study to reference compounds was conducted and it was concluded that the concentration of fluorescent molecules is about 400 μg/g of potsherd. At the same time, a methodology for organic residue recovery from modern potsherds was designed on the basis of intact olive oil as model sample and isooctane as extracting solvent. The extraction efficiency of developed protocol was evaluated monitoring the intensity of chlorophyll’s a emission band. Afterwards, two potsherds were spiked with phenolic standard mixture and with olive oil and were transferred to a custom-built chamber for artificial aging upon UV-irradiation. The absorption and fluorescence study of aged samples showed that nonconjugated double and triple bonds in lipid structures present in olive oils convert into conjugated bonds in di- and tri-enes carrying carbonyl functional groups (secondary oxidation products) and that phenolic acids photo-decompose via cleavage of acrylic acid group.

Language

English

Subject

Archaeometry

Artificial aging

Fluorescent biomarker

Organic residue

Phenolic acid

Potsherd

Αρχαιομετρία

Κεραμικό υπόστρωμα

Οργανικό κατάλοιπο