Organic Remains in Early Christian Egyptian Metal Vessels: Investigation with Fourier Transform Infrared Spectroscopy and Gas Chromatography–Mass Spectrometry

Organic remains preserved on eight copper alloy artifacts of the Byzantine Collection of the Benaki Museum with an Egyptian provenance were investigated, implementing a multi-analytical approach combining microscopy-FTIR and GC/MS. The transmission spectra of powder samples provided important information on the vessels regarding inorganic and organic components. In the latter case, subsequent extractions with a range of solvents allowed discrimination of components with different polarities and provided data on the suitability of the solvents for the acquisition of more informative spectra. GC/MS was implemented for the detailed characterization of the compounds present in the samples because of the complex nature of the residues preserved. A wide range of fatty acid oxidation products was identified, including a series of α, ω-dicarboxylic acids typical of such remains. In addition, vicinal dihydroxy-docosanoic and dihydroxy-eicosanoic acid, oxidation products of erucic and gondoic acid, respectively, were detected. Both are found in abundance in oils from plants belonging to the Brassicaceae family and imply their multiple uses in medieval Egypt.