GC/MS Characterization of Beeswax, Protein, Gum, Resin, and Oil in Romano-Egyptian Paintings (original) (raw)
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Heritage
This article presents results from a binding media survey of 61 Romano-Egyptian paintings. Most of the paintings (51) are the better-known funerary mummy portraits created using either encaustic or tempera paint medium. Samples from all the paintings (on wooden panels or linen shrouds) were analyzed with gas chromatography/mass spectrometry (GC/MS) to identify waxes, fatty acids, resins, oils, and proteins in one sample. Analytical protocols that utilized three separate derivatization techniques were developed. The first analysis identified free fatty acids, waxes, and fatty acid soaps, the second characterized oils and plant resins, and the third identified proteins. The identification of plant gums required a separate sample. Results showed that fatty acids in beeswax were present as lead soaps and dicarboxylic fatty acids in some samples was consistent with an oxidized oil. The tempera portraits were found to contain predominantly animal glue, revising the belief that egg was the...
is published by Morana RTD d.o.o. www.Morana-rtd.com e-PRESERVATIONScience This paper is based on a presentation at the sixth international meeting of the Users'Group for Mass Spectrometry and Chromatography (MASC) in Pisa, Italy, 5th – 6th June 2013. Abstract Romano-Egyptian panels in the collections of the J. Paul Getty Museum dating to 180-200 A.D. were found to contain proteinaceous paint media. Animal glue was detected in the ground layers of all three panels using Enzyme-linked immunosorbent assay (ELISA) and mass spectrom-etry. Results were verified with gas chromatography/mass spectrometry (GC/MS) by the identification of 4-hydroxyproline, the major amino acid that occurs in animal glue collagen but not egg albumin. The animal species used to make the glue was identified as cow (Bos taurus) by using nano-liquid chromatography-electrospray ionization-tandem MS (nanoLC-ESI-MS/MS). A paint fragment from the Bearded Man contained tryptic peptides, type III collagen α1 chain,...
Journal of Cultural Heritage, 2014
The Saadian tombs from the era of sultan Ahmed al-Mansour (1574-1603) are beautifully decorated and have always been a major attraction for visitors to Marrakesh. The central mausoleum, named the Hall of Twelve Columns, encloses the tombs of Ahmed al-Mansour and his family. The hall has a huge vaulted ceiling, carved cedar doors, opening windows with wooden marquetry screen (Mashrabiya), and grey Italian marble columns. This paper presents the first attempt to identify the organic materials used by the Moroccan artisans. A GC/MS analytical procedure was used for the characterization of lipids, waxes, resins, pitch, tar, proteinaceous and saccharide materials in the same paint micro-sample. The analytical study identified the organic materials used in the polychrome and gilded decorations of the walls, ceiling and dome of the hall. Data showed that the polychrome decorations were painted using animal glue as a binder, and highlighted the treatment of the wall surface with linseed oil and the retouching of the paintings based on a saccharide binder. The use of a proteinaceous-resinous-oil mixture, applied on a proteinaceous preparation layer, for the gilded decorations revealed a very similar technique to that used at the time in Europe for mural paintings.
Analytical Chemistry, 2006
A novel GC/MS analytical procedure for the identification of lipids, waxes, proteins, and resinous materials in the same microsample from painted works of art has been optimized. It is based on a sample multistep chemical pretreatment (solvent extractions and microwave-assisted chemolysis) that is able to separate the various organic components into different fractions, which are suitably treated and derivatized before analysis. In particular, the procedure allows the complete saponification of wax esters and the completeness of the Cannizzaro type reaction of shellac acids in conditions that are suitable also for glycerides saponification. The method was tested on reference materials for the identification of proteinaceous binders (egg, collagen, casein) on the basis of the quantitative determination of the amino acid profile and the identification of glycerolipids (linseed oil, poppy seed oil, walnut oil, and egg), plant resins (Pinaceae resins, sandarac, mastic, and dammar), animal resins (shellac), tars or pitches, and natural waxes (beeswax, carnauba wax) on the basis of the determination of fatty acid, alcohol, and hydrocarbon profiles and of significant terpenic molecular markers. The procedure was applied to the characterization of three old paint microsamples. Animal glue, egg, linseed oil, beeswax, Pinaceae resin, dammar, and shellac were the identified materials found in mixtures and recognized as original and/or restoration substances.
Gas chromatography/mass spectrometry of oils and oil binders in paintings
Journal of Separation Science, 2008
Gas chromatography/mass spectrometry of oils and oil binders in paintings A GC/MS procedure has been developed, optimized, and applied to characterization of oil binders in paintings. The procedure involves hydrolysis of lipids to fatty acids (FAs) and derivatization of FAs to fatty acid methyl esters (FAMEs) by a solution of sodium methanolate in methanol at an elevated temperature. FAMEs are analyzed by temperature-programed GC followed by full-scan MS. Old and dried samples are subjected to extraction of nonpolymerized FAMEs into dichloromethane prior to hydrolysis. The method provides a good repeatability of results and has been applied to the characterization of common plant oils used in paintings, to commercial oil and tempera paints, to model painting samples, and to samples taken from real paintings. The fresh oils and binders can readily be identified and characterized. The ratio of the methyl esters of palmitic and stearic acids can be used to characterize oil binders in old works of art.
Study of Egyptian mummification balms by FT-IR spectroscopy and GC-MS
2014
Fourier transform infrared spectroscopy (FT-IR) and gas chromatography coupled with mass spectrometry (GC-MS) were used in order to analyse twelve mummification balms from mummy skulls of the Musée des Confluences (Lyon, France). For FT-IR analyses, a simple extraction protocol in dichloromethane and water allowed to separate the materials by their polarity. This study clearly shows that the organic fraction is the main constituent of the Egyptian balms and hides much information in the bulk analyses (made without any extraction). Infrared absorption reveals the presence of (i) several organic materials (proteins, polysaccharides), (ii) inorganic salts (CaSO 4 , CaCO 3 and NH 4 Cl) possibly used as natron in ancient time, and (iii) ochre used in order to dye the bandages. GC-MS analyses were made on the organic fraction of extracted balms, previously trimethylsilylated before injection. Biomarkers and degradation products of oils, fats, resins (with oleanene, lupene, lanostane, masticadiene, and abietane compounds) and beeswax were found. These materials were often used in combination. Many identified byproducts (di and triterpenic molecules, hydroxylated fatty acids, etc) give us the opportunity to discuss the different degradation reactions taking place in such archaeological material. Furthermore, beeswax was identified in numerous samples thanks to the presence of long chain alkanes, long chain fatty acids and palmitate ester. In one balm, the co-occurrence of brassicaceae oil chemical markers and cholesterol (and its degradation products) shows the combine use of oil and fat. Finally, a great correlation and complementarity was observed between the two analytical techniques.
Journal of Archaeological Science, 2017
Twenty three samples of Egyptian organic materials, spanning from the Old Kingdom to the Copto-Byzantine Period, were investigated by gas chromatography-mass spectrometry. The sample set was comprised of ten balm samples from human mummies, three balms from shrews, and ten samples of residues scraped from jars and amphora from storehouses. This research program was undertaken with two main goals: Firstly to provide complementary data on the mummification balms from both humans and animals with an emphasis on the occurrence of bitumen in mummification mixtures. Secondly to explore whether the jar residues were mixtures that were used for mummification purposes or whether they were pure ingredients stored for various uses including ritual practices. The analysis highlighted that the most abundant constituents of the mummification balms were: fats or oils, waxes, conifer resin, pitch, mastic resin, castor oil, and bitumen. Balms from animal mummies were not found to be significantly different from the balms from human mummies. Residues from potsherds appeared to belong to two categories: pure products (fats and castor oil) and mixtures containing fats, Pinaceae resin and pitch, mastic resin, and castor oil, i.e. the constituents also identified in mummification balms. The mixtures were thus residues of preparations for ritual practices and embalming. This study demonstrates that bitumen is underestimated by the chemical approach currently applied in most archaeometric studies of Egyptian organic residues, which are better suited for the identification of lipids and resinous materials. We thus applied a specific analytical design, targeted at bitumen. Bitumen from the Dead Sea was conclusively identified using as reference materials for comparison, i.e. the present day bitumen from the Dead Sea floating blocks, as well as several bitumens from mummification balms and bitumen lumps unearthed from the archaeological site of Tell Yarmouth near Jerusalem in Israel.
Proceedings of the National Academy of Sciences of the United States of America, 2021
Black organic coatings and ritual deposits on ancient Egyptian coffins and cartonnage cases are important and understudied sources of evidence about the rituals of funerary practice. Sometimes , the coatings were applied extensively over the surface of the coffin, resembling paint; in other cases, they were poured over the mummy case or wrapped body, presumably as part of a funerary ritual. For this study, multiple samples of black coatings and ritual liquids were taken from 20 Egyptian funerary items dating to a specific time period (c. 943 to 716 BC). Multiple sampling from each object enabled several comparisons to be made: the variability of the black coating within one application, the variability between two applications on one object, and the variability from object to object. All samples were analyzed for lipids using gas chromatography-mass spectrometry (GC-MS), and 51 samples from across the 20 items were further analyzed for the presence of bitumen using solid phase separation followed by selected ion monitoring GC-MS. The majority of the black substances were found to comprise a complex mixture of organic materials, including bitumen from the Dead Sea, conifer resin, and Pistacia resin, providing evidence for a continuation in international trade between Egypt and the eastern Mediterranean after the Late Bronze Age. Both the coating and the anointing liquid are very similar to mummification balms, pointing to parallels with Egyptian embalming rituals and raising questions about the practical aspects of Egyptian funerary practice. archaeology | ancient Egypt | coffins | chromatography | mass spectrometry
Characterization of an unusual coating on funerary portraits from Roman Egypt circa 100-300AD
Heritage Science
This paper details the investigation of a discrete coating observed on a group of Egyptian panel paintings, six mummy portraits and one funerary panel, dating from first-third century CE. Six mummy portraits in this group are encaustic, and the funerary panel is tempera using an animal glue binder. An accretion or coating has been observed on the surface and recesses of the paint layers on these panels. Examination of the portraits using ultraviolet radiation revealed an irregular visible fluorescence on the surface. On the mummy portraits, the fluorescence often extends only as far as where the linen wrappings would have secured the portrait to its mummy. Under magnification, the coating appears as a crizzled encrustation. Material exhibiting these characteristics was sampled from the surface of all seven panels. Initial analysis of samples from four panels by gas chromatography mass spectrometry (GC/MS) and enzyme-linked immunoassay (ELISA) revealed the presence of egg. Subsequent...