DOI: 10.17169/refubium-42364
title: GC-MS analysis of the content of Byzantine Globular Amphorae from Ain Wassel (Tunisian High Tell)

description: Materials and Methods: The samples are first cleaned mechanically by using a drill. Then they are ground to a fine powder by using a mortar enabling further extraction. Three extraction protocols have been applied according to Pecci et al. 2013 (1); Mottram et al.1999 (2); Pecci et al. 2013a/Mottram et al.1999 (3). Mottram H.R., Dudd S.N., Lawrence G.J., Stott A.W., Evershed R.P., 1999 - New chromatographic, mass spectrometric and stable isotope approaches to the classification of degraded animal fats preserved in archaeological pottery, Journal of Chromatography A, 833: 209-221. doi: 10.1016/S0021-9673(98)01041-3 Pecci, A. Identifying wine markers in ceramics and plasters using gas chromatography–mass spectrometry. Experimental and archaeological materials. Journal of Archaeological Science 2013, 40, 109-115. DOI: 10.1016/j.jas.2012.05.001 Pecci A., Cau M.A., Garnier N., 2013a - Identifying wine and oil production: analysis of residues from Roman and Late Antique plastered vats, Journal of Archaeological Science, 40 (12): 4491-4498. doi: 10.1016/j.jas.2013.06.019 Instrument used: GC-MS: Agilent 5977E MSD with 7820A GC. The mass range was scanned in the range of m/z 40 – 600. The GC oven temperature was held at 50°C for 1 min, then increased at 5°C/min up to 320°C and held isothermally for 10 min. The injection was done in split mode with a split ratio of 5:1. The injection Temperature was 320°C and the total run time was 75 mins. The column used was HP-5MS (Agilent Technologies), a (5%-phenyl)-methylpolysiloxane phase capillary column with length 30m and diameter 0.250 mm. The heater temperature was 320°C and MS transfer line temperature was 280°C. Dotriacontane is used as an internal standard marker compound in all samples and the first large peak signifies the unused derivatization reagent N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA containing 1% trimethylsilyl chloride). The 1% trimethylsilyl chloride is added as an additional silylation reagent and catalyzes reactions of hindered functional groups in polyfunctional compounds like secondary alcohols, secondary amines and amides. The Chromatograms obtained from the GC-MS Analysis of all the samples were analyzed manually by using the Agilent Quantitative and Qualitative Software (Mass Hunter qualitative / quantitative, Vs. B.07.00). For peaks not assigned by the automated procedure using a data base containing more than 150 biomarkers in the “Quantitative Analysis tool”, we generate the mass spectra of the chromatogram peaks and search for the possible compounds using the NIST Library. By comparing these compounds predicted by the NIST Library with the generated mass spectra, we assign the compound labels. The observed retention times of the detected compounds are summarized in the table.
description: Protocol 1 enabled to detect TMS derivatives of the polar, short chain fatty acids and some traces of TMS derivatives of medium chain fatty acids as well. Protocols 2 and 3 enabled to extract TMS derivatives of long-chain fatty acids, some sterols and some non-polar alkane compounds as well.
description: Four (4) samples of so-called Byzantine Globular Amphorae from the excavation of the rural farm at Ain Wassel (High Tunisian Tell) have been considered for organic residue analysis via gas chromatography-mass spectrometry (GC-MS) in order to better understand the function of this type of transport and storage container and shed new light on still poorly understood trade and consumption practices in Late Antique/Early Medieval North Africa. The content of this typological group of amphorae dating to the 7th-8th(?) century AD is still unknown. Following samples of the bottom of "anfora a fondo umbonato e ombelicato" (Maurina 2019), corresponding to the type Bonifay 65 (Bonifay 2004) have been analyzed in this study: Maurina 2019, Fig. 4.9, 14-17. The obtained results are available here in tabular form. Bibliographic references: Maurina, Barbara. “Contenitori Da Trasporto e per La Conservazione.” In Rus Africum IV: La Fattoria Bizantina Di Aïn Wassel, Africa Proconsularis (Alto Tell, Tunisia): Lo Scavo Stratigrafico e i Materiali, edited by Barbara Maurina and Mariette de Vos Raaijmakers, 245–94. Archaeopress, 2019. https://doi.org/10.2307/j.ctvndv6tz.8 Vos Raaijmakers, Mariette de, and Barbara Maurina, eds. Rus Africum IV: La Fattoria Bizantina Di Aïn Wassel, Africa Proconsularis (Alto Tell, Tunisia): Lo Scavo Stratigrafico e i Materiali. Archaeopress, 2019. https://doi.org/10.2307/j.ctvndv6tz Bonifay M., Etudes sur la céramique Romaine Tardive d'Afrique, British Archaeological Reports, 2004
description: In general on organic residue analysis and the concept of archaeological biomarkers, see: Evershed, R. P., Organic residue analysis in Archaeology: The archaeological biomarker revolution, Archaeometry 2008, 50, 895-924. DOI: https://doi.org/10.1111/j.1475-4754.2008.00446.x.