1,721,131 research outputs found
The importance of the scientific support to the preservation of cultural heritage: 2- The characterisation of paint binders
No full textThe importance of the scientific support to the preservation of cultural heritage: 1- Pollutants and organic materials in the Museum Environment
No full textThe characterization of beeswax in works of art by gas chromatography-mass spectrometry and pyrolysis-gas chromatography-mass spectrometry procedures
No full textPyrolysis (Py) with in situ derivatisation with hexamethyldisilazane–gas chromatography–mass spectrometry (GC–MS) and a gas chromatography–mass spectrometry procedure based on microwave-assisted saponification were used to identify the organic components in small sized beeswax samples. With the latter procedure quantitative recoveries can be made and hydrocarbons, alcohols and ω-1-diols in the neutral fraction, and fatty acids and ω-1-hydroxy acids in the acidic fraction can be efficiently separated and detected. Both procedures were used to characterise a wax anatomic sculpture “The Plague” (1691–1694) by Gaetano Zumbo, resulting in the identification of beeswax and a Pinaceae resin. The GC–MS analysis brought to light some essential differences in beeswax composition between the raw material and the old modelled wax thus giving some clear indications about the recipe used by the sculptor
An integrated mass spectrometric and molecular imaging analytical approach to identify and localise constituents in paintings applied to gilded multilayer structures from 14th to 16th C works of art
No full textA multi-anal. approach is presented to det. the org. and inorg. compn. of gilding samples that have a multi-material and multi-layered structure. The effectiveness of the combination of mass spectrometric methods to identify org. materials and mol. imaging to localize org. and inorg. constituents is explored by a detailed characterization of the materials used in three different gilded decorations on wall paintings. The results are interpreted in the art tech. and historical context of gilding
The development of a gas chromatographic–mass spectrometric analytical procedure for the determination of lipids, proteins and resins in the same paint micro-sample avoiding interferences from inorganic media
No full textThis paper presents a GC-MS analytical procedure for determining proteinaceous materials, glycerolipids, natural waxes and terpenoid resins in the same paint micro-sample. The procedure is also reliable when high amounts of interfering inorganic pigments, dryers and charges are present. The characterisation of proteinaceous binders in a paint sample can be subject to analytical interferences by inorganic materials. Such materials may form complexes with functional groups of proteins, thus preventing their efficient derivatisation, which is necessary prior to GC analysis. For this reason an analytical procedure has been developed based on two extractions and a clean-up step, in order to obtain two fractions: a lipid-resinous fraction and a proteinaceous fraction. The lipid-resinous fraction is subjected to salification/saponification assisted by microwaves, followed by acidification, extraction, derivatisation and GC-MS analysis. The proteinaceous fraction is analysed by CC-MS after hydrolysis and derivatisation of the freed amino acids. The desalting step is applied before the hydrolysis, and is based on the use of the monolithic sorbent tip technology with a C4 stationary phase. Reference paint replicas of egg, casein and animal glue were prepared with and without several metals containing pigments, and used to develop and validate the analytical procedure. The procedure proved to be efficient in desalting the proteinaceous materials both from cations and anions. Although non quantitative, it is reliable in the analysis of samples whose content of extractable proteins is <1 mu g, thus showing it to be suitable for the characterisation of paint samples. An example of how the analytical procedure was used to characterise a sample from a 15th century panel painting is also discussed. (C) 2009 Elsevier B.V. All rights reserved
Identification of garlic in old gildings by Gas Chromatography- Mass Spectrometry
No full textThe proteinaceous content of garlic (Allium sativum) was characterised according to its amino acid composition by using a gas chromatography-mass spectrometry (GC-MS) analytical procedure. The procedure was tested on fresh and aged garlic samples as well as on reference gilding specimens prepared according to old recipes. The proteinaceous pattern showed a characteristic distribution of amino acids with glutamic acid being the major component. The average amino acidic composition was: glutamic acid (Glu; 29%), aspartic acid (Asp; 17%), serine (Ser; 11%), alanine, glycine, valine, leucine, lysine and phenylalanine (Ala, Gly, Val, Len, Lys and Phe; 5-6%), isoleucine, proline and tyrosine (Ile, Pro and Tyr; 2-3%), methionine and hydroxyproline (Met and Hyp; 0.5%). In order to distinguish this material from animal glue and egg, which are the other proteinaceous media commonly used in gilding techniques, a database of amino acid percentages of the three proteins was built up and submitted to principal component analysis. Three separate clusters were obtained, allowing the protein identification. The application of the procedure on several gilding samples from Italian wall and easel paintings (13th-17th century) permitted to evidence the use of garlic as a gluing agent. (c) 2005 Elsevier B.V. All rights reserved
Molecular pattern recognition of fresh and aged shellac
No full textTwo GC-MS procedures for the characterization of shellac, an animal resin widely used in the field of art, were developed. One procedure was based on pyrolysis assisted by the hexamethyldisilazane reaction on-line with GC-MS and the other on the saponification of the sample assisted by microwave followed by GC-MS analysis. The former is a rapid and valuable method for resin identification and the latter gives a more in depth understanding of its composition. Butolic, aleuritic and its derivative acids together with typical sesquiterpenoid compounds were the main molecules identified and used as markers for the molecular pattern recognition of the resin in fresh and old samples (19(th) century shellac from the Solvemini Collection and gilding samples from the 15(th) century frescoes of the Duomo of Monza)
Analytical pyrolysis of proteins in samples from artistic and archaeological objects
Full text linkThe paper presents a study of proteins found in artistic and archaeological objects based on analytical pyrolysis. Proteins (mainly egg yolk and/or egg white, casein, animal glue and collagen) have been extensively used as paint binders, adhesives and varnishes in mural and easel paintings, and they can be found in archaeological findings, such as bones and skin tissues. In order to overcome limitations of wet chemical methods arising from the reduced solubility of aged proteins in samples of cultural heritage, a combination of analytical pyrolysis techniques was used to characterise reference materials, paint reconstructions and samples from different historical periods (2nd century BC-20th century AD) and geographical origins, which were collected from paintings and archaeological findings. In particular evolved gas analysis mass spectrometry (EGA/MS), pyrolysis coupled with gas chromatography/mass spectrometry (Py/GC/MS) and double shot pyrolysis/gas chromatography/mass spectrometry (DSP/GC/MS) were used. This analytical approach allowed us to characterise and differentiate the proteinaceous media, investigate their thermal behaviour and evidence changes occurring with ageing. Data clearly indicate that egg, casein and animal glue can be identified and distinguished in a sample of unknown composition using each of the analytical pyrolysis techniques used. With time though differences tend to disappear to the extent that extremely degraded samples present pyrolytic profiles extremely similar to each other, irrespective of the nature of the proteins present. The data also indicate that proteins tend to become more thermally stable with ageing, suggesting that extensive intramolecular and intermolecular aggregation, and/or covalent cross-linking occur with time
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