1,721,040 research outputs found
A scientific and Archivistic investigation on Italian scagliola altar frontals
No full textanalyses of some pigments found in fragments, many dyes and pigments have been identified and the technique clarifie
Validation Study of Selected Ion Flow Tube-Mass Spectrometry (SIFT-MS) in Heritage Science: Characterization of Natural and Synthetic Paint Varnishes by Portable Mass Spectrometry
No full textThe identification at molecular level of organic materials in heritage objects as paintings requires in most cases the collection of micro-samples followed by micro-destructive analysis. In this study, we explore the possibility to characterize natural and synthetic resins used as paint varnishes by mean of non-invasive analysis of released volatile organic compounds (VOCs) through selected ion flow tube-mass spectrometry (SIFT-MS). SIFT-MS is a portable direct mass spectrometric technique that achieves the analysis of VOCs at trace levels in real time, by controlled ultra-soft chemical ionization using eight different chemical ionization agents. We tested the portable instrumentation on different reference resins used as paint varnishes, both natural (mastic, dammar, and colophony) and synthetic (Paraloid B67, MS2A, Regalrez 1094, and polyvinyl acetate), to evaluate the possibility to acquire qualitative data for the identification of these materials in heritage objects avoiding any sampling. This new analytical approach was validated by comparison with the traditional approach for VOCs analysis based on solid phase micro extraction-gas chromatography/mass spectrometry (SPME-GC/MS) analysis. The results demonstrate the use of SIFT-MS as an in situ non-invasive and non-destructive mass spectrometric technique to identify organic materials, such as paint varnishes. [Figure not available: see fulltext.]
Triarylmethine dyes: Characterization of isomers using integrated mass spectrometry
No full textTriarylmethine dyes, such as Methyl and Crystal Violets, Diamond green and Magentas, produced since the late nineteenth century, consist of complex mixtures of homologous compounds, often differing only for the presence or position of the same substituent on the aromatic rings. In this paper, Liquid Chromatography-High Resolution Mass Spectrometry (HPLC-HRMS) was used for the characterization of the profile of three dyes: Methyl Blue, Methyl Violet and Fuchsine. The comprehension of dye synthesis and production strategies was often achieved by analyzing the single components by diode array detector. Nevertheless, the nature of the individual components needs to be confirmed by tandem mass spectrometric techniques through the solving of the structural issues. The analysis of standards and reference materials by tandem high resolution mass spectrometry allowed us to identify peculiar fragmentation pathways for the components of magentas and methyl violet dyes. The results highlighted the importance to undertake the measurements both in negative and positive ionization mode. The elucidation of specific fragmentation patterns allows the discrimination between different classes of compounds, while the identification of specific fragment ions allows one to distinguish isomers belonging to the same series
Investigating the composition and degradation of wool through EGA/MS and Py-GC/MS
No full textWool has been the most widely used textile fiber in Europe since the Iron Age. It was largely employed to weave fabrics and clothes, and also for artistic purposes such as producing tapestries. This kind of artworks is among the most fragile of our heritage and is often in bad preservation conditions. Thus, the knowledge on the degradation processes of wool fibers is crucial for conservation issues. In the present study, we tested the potentialities of Pyrolysis coupled with Gas Chromatography and Mass Spectrometry (Py-GC/MS) and Evolved Gas Analysis coupled to Mass Spectrometry (EGA/MS) for the characterization of woolen reference samples, also subjected to artificial ageing, and of historical and archeological samples. The reference sheep wool yarns were prepared with different mordants and dyes, and have been analyzed both after storage in the dark for three years after preparation, and artificially aged for different time intervals and at different relative humidity values. We created a detailed pyrolysis database, evidencing the phenomena occurring with ageing and including camel wool for comparison. The ageing process undergone by the proteinaceous fraction of wool has also been investigated through monitoring specific fragment ions in the EGA profiles. The relevant parameters affecting the degradation process identified in this study match those assessed in previous investigations by different and complementary techniques, thus validating our approach. We proved that the novel approach based on EGA/MS is suitable for quickly assessing the conservation conditions of the woolen yarns and represents an advantage with respect to more time-consuming and complex methods, such as GC/MS or High Performance Liquid Chromatography (HPLC)
A mass spectrometric study on tannin degradation within dyed woolen yarns
Full text linkNatural tannins from various plants have been used throughout human history in textile dyeing, often as mordant dyes. The ageing behavior of these dyes is a challenge in conservation science, requiring a thorough knowledge of the textile–mordant-dye system. In this work, we analyzed reference wool yarns dyed with natural tannins from oak gallnuts, walnut (Juglans regia), and catechu (Acacia catechu), after artificial ageing. To gain insights on the composition of the dyestuffs and on how they aged, an analytical procedure based on extraction with Na2EDTA/DMF (ethylenediaminetetraacetic acid/dimethylformamide) and high-performance liquid chromatography (HPLC) analysis using high-resolution mass spectrometry detection was used. Since conventional reversed-phase (RP) columns usually show poor retention efficiency of highly polar compounds such as tannins, an RP-amide embedded polar group stationary phase was used to achieve optimal retention of the most polar compounds. Tannins from oak gallnuts showed little degradation after ageing, while a significant increase in the content of hydroxybenzoic acids was observed for tannins from walnut and catechu. Finally, the analytical procedure was applied to characterize the tannin dyes in historical tapestries from the 15th to 16th century, and the results were discussed in comparison with the reference yarns
Correction to: The analysis of the Saltzman Collection of Peruvian dyes by high performance liquid chromatography and ambient ionisation mass spectrometry (Heritage Science, (2019), 7, 1, (81), 10.1186/s40494-019-0319-1)
No full textIn their article [1], the authors stated the following: “One of the laboratory’s first major projects in the 1970s resulted in the Saltzman Collection of Peruvian dyes, a notebook containing recipes and descriptions of materials collected and prepared by Saltzman. The notebook, currently held in the collections at UCLA, also contains skeins of wool (not specified, but presumably from domestic sheep), alpaca and cotton yarns, prepared by either Dr. Saltzman himself or more likely one of his associates [emphasis added].” The authors would like to correct their article to give appropriate credit to the associate of Dr. Saltzman, Kay Antúnez de Mayolo, who worked as a field assistant under a grant from the Smithsonian Institution to the Institute of Geophysics and Planetary Physics at the University of California Los Angeles in the 1970s. She and her husband Erik traveled throughout Peru collecting botanical specimens and preparing dyes as described in her report [2]. Mr. Max Saltzman—not Dr. Saltzman, as we had presumed incorrectly—was the project administrator of that grant and received from Ms. Antúnez de Mayolo the original collection of dye samples and report that were sent to UCLA at the termination of the field work. The authors would therefore like to correct the above text to the following: “One of the laboratory’s first major projects in the 1970s resulted in a collection of Peruvian dyes, part of which consisted of a notebook containing recipes and descriptions of materials collected and prepared by Kay Antúnez de Mayolo, a botanist who was working as a field assistant for Mr. Saltzman [3, 4]. The notebook, currently held in the collections at UCLA, also contains skeins of wool, alpaca and cotton yarns, prepared by Ms. Antúnez de Mayolo during the field work in May to September 1977.” Where the authors have referred to the collection and preparation of the samples elsewhere in the article, this should additionally be credited to Ms. Antúnez de Mayolo. The authors are grateful to Ms. Antúnez de Mayolo for alerting them to this oversight and for providing a copy of the unpublished report to Dr. Armitage
The analysis of the Saltzman Collection of Peruvian dyes by high performance liquid chromatography and ambient ionisation mass spectrometry
Full text linkYarn samples from the Saltzman Collection of Peruvian dyes were characterized by several different analytical techniques: high performance liquid chromatography with both diode array detection (HPLC-DAD) and electrospray ionisation with tandem mass spectrometry (HPLC-ESI-Q-ToF), direct analysis in real time (DART) mass spectrometry and paper spray mass spectrometry. This report serves primarily as a database of chemical information about the colorants in these dye materials for those studying ancient South American textiles and their colorants. We also provide a comparison of the results obtained by currently widespread HPLC techniques with those of two different ambient ionisation direct mass spectrometry methods to highlight the advantages and disadvantages of these approaches
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Study of the molecular compositions of ointments from the 18th baroque pharmacy of the Capuchin monastery in Hradčany (Prague, Czech Republic)
Full text linkA multi-analytical approach based on four different analytical methods was used for the first time to study six historical ointments from the 18th century belonging to the baroque pharmacy of Capuchin Monastery in Hradčany (Prague, Czech Republic) in order to gain information on the ointment formulation, the presence of active substances, and also possible chemical modification deriving from the procedures used for their preparation. All ointments were initially characterized by gas chromatography/mass spectrometry following saponification, extraction and derivatization to identify the main classes of ingredients. The volatile organic compounds emitted by the ointments were then characterized by gas chromatographic analysis following solid-phase microextraction, providing complementary information on the possible more volatile and active ingredients present in the ointments. Finally, the botanical/animal origin of triacylglycerols was investigated by liquid chromatography-high resolution mass spectrometry, while the presence of beeswax was proved by flow injection analysis. The results obtained were used to hypothesize the probable original medical purpose of the ointments by comparing the results with historical recipes and the period literature. The use of this comprehensive multi-analytical approach allowed us to contribute to the knowledge of ancient ointments and to obtain information on the alteration of the chemical compounds in the ointment formulations
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