Study of organic residues in archaeological ceramics by mass spectrometry.

EVELYN L. BONIFAZI; VALERIA P. CAREAGA; IRENE LANTOS; MARTA S. MAIER

Río de Janeiro

Congreso; 1st Iberoamerican and 6th BrMass Conference on Mass Spectrometry; 2016

The study at a molecular level of archaeological organic residues provides relevant information on past human activities. Theorganic compounds are absorbed into the porous matrix of ceramics in contact with food during cooking and / or storage, favoringan exceptional preservation of some types of compounds, such as lipids (1, 2). The usual method of lipids analysis inarcheological samples involves hydrolysis and derivatization of acylglicerides and phospholipids to obtained FAME (fatty acidmethyl ester). Then this is analyzed by GC and GCMS.Because fatty acids are unspecific biomarkers it is necessary to studyresiduary acylglicerides and phospholipids which are better biomarkers of original source (3, 4). This work focuses on the lipidprofile analysis of organic residues from reference samples, replica and archeological ceramic vessels. It was required to carryout optimization and application of methodologies based on liquid chromatographymassspectrometry (LCESIand LCAPCI)andtandem mass analysis. Total lipid were analyzed, samples were extracted with chloroform/ methanol (2:1) and injected directlyinto LCMS(Bruker MicrOTOFQII). Four varieties of native Zea mays L. (Pisingallo, Chullpi, Dentado blanco and Capia) werecharacterized. Using these results as a reference, the lipid profiles of residues absorbed into fragments of replica andarchaeological ceramics were characterized. The results showed the presence of tridiandmonoacylglicerides, andphospholipids in the maize samples, with characteristic profiles of vegetable oils. It was observed that part of the lipids extractedfrom replica and archaeological ceramics were preserved as intact acylglicerides and degradation products as minor components.Hydroxylated acylglycerides derivatives and possible hydroperoxides species were identified as the main degradation products.Through high sensitivity and resolution of the technique used and the exhaustive tandem mass analysis it was possible tocharacterize the analyzed samples. The lipid profiles obtained contribute to our knowledge on diet and eating habits of pastcultures.