8 research outputs found
A combination of invasive and non-invasive techniques for the study of the palette and painting structure of a copy of Raphaelâs Transfguration of Christ
We thank the owner of the painting Mr. F. Fernandez FĂĄbregas and the
research group FQM-338 (University of Granada) for letting us use its facilities.
We also thank Maria José Campos for the preparation of the cross-section
samplesAll the authors belong to the research team Unit of Non-Invasive Analytical
Techniques Unit (University of Granada, Spain) funded by EQC2018-004952-P
and AâHUMâ164âUGR18 Projects, currently active. All the authors read and
approved the fnal manuscript. EM: Professor of Analytical Chemistry applied
under Cultural heritage at the Department of Analytical chemistry of the
University of Granada, Spain. The author contributed to the examination of
the Transfguration of Christ, using photography, SEMâEDX, and performed
the ”RS and ”ATR-FTIR analyses; and contributed to the interpretation of the
datasets, contextualization of data, and writing of the manuscript. RB: Full
Professor of Analytical Chemistry at the Department of Analytical chemistry of
the University of Granada, Spain. The author contributed to the examination of
the painting, sampling, contextualization of the painting, elaboration of tables
and fgures, contextualization of data, and participated in the interpretation
of the datasets. The author read and approved the fnal manuscript. JDM-R:
Professor of Mineralogy at the Department of Mineralogy and Petrology of
the University of Granada, Spain. The author provided the interpretation of the
mineralogical data. GCh: Professor of Mineralogy Applied under Cultural Heritâ
age at the Department of Earth Sciences of the University of Torino, Italy, Chief
Scientist at the Getty Conservation Institute in Los Angeles, CA (director of the
Science department for 11 years). The author works now as a freelance conâ
sultant in the feld of Conservation of Cultural heritage. The author read and
approved the fnal manuscript. PS: Scientist at the SETI Institute and founder of
eXaminart LLC. The author develops miniature X-ray analytical instruments for
Space exploration ((e.g. the NASA CheMin XRD instrument inside the Curiosity
Mars rover) and portable instruments dedicated to cultural heritage. The
author contributed to the examination of the Transfguration of Christ, using
pXRD. The author read and approved the fnal manuscript. JLV: Full Profesâ
sor of Analytical Chemistry at the Department of Analytical chemistry of the
University of Granada, Spain. The author contributed to the Transfguration
of Christ, using photography, SEMâEDX; contributed to the interpretation of
the datasets, the contextualization and revision of data. All authors read and
approved the fnal manuscript.The main objective of this study is to establish an appropriate method for the characterization of the pigments, materials and structure of the paint layers in a copy of the painting the Transfiguration of Christ by Raffaello Sanzio. A multi-technique approach that combines elemental, molecular and structural analyses and involves optical microscopy (OM), scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDX), mu-Attenuated Total Reflection-Fourier Transform InfraRed (mu ATR-FTIR), mu-Raman spectrometry (mu RS) and non-invasive portable diffractometer (pXRD) was used. Our results revealed that this copy of the Transfiguration was executed with a palette, which includes white lead (cerussite and hydrocerussite), lazurite from lapis lazuli pigment, red and yellow earths (goethite, hematite and lepidocrocite), lead tin yellow, cinnabar, red lake, smalt and bone black, and fillers such as calcite, baryte (an impurity associated to some pigments), and traces of colorless powdered glass. A secondary objective of this research was the application of non-invasive in situ pXRD measurements, which do not require painting sampling and helped to confirm some inconclusive results obtained with other techniques regarding the artist's palette. The results showed the crystalline nature of all the pigments identified, which were known from ancient times and available during the 16th and 17th. Lastly, the used of C-14 accelerator mass spectrometry determined that the canvas date was 1451-1633 AD (with a 95% confidence level). Although the main focus of the work was to improve the analytical methodology to better understand the artist's palette, our results will further help us to explore the authorship of the copy or the school that executed it.Non-Invasive Analytical
Techniques Unit EQC2018-004952-PProyecto de investigaciĂłn FEDER / Junta de
AndalucĂa-ConsejerĂa de EconomĂa y Conocimiento / A â HUM â 164 â UGR18
Non-Invasive Study of the Pigments of a Painting on Copper with the Inscription âBoceto di Pablo Veroneseâ on the Back
The palette used on a small painting on copper support, with the inscription âBoceto di
Pablo Veroneseâ on the back, was characterized. Non-invasive techniques such as X-ray diffraction
(XRD) and hand-held X-ray fluorescence (XRF) were proven to be highly effective for this. The
objectives of the proposed work were twofold. On the one hand, the objective was the study, in situ,
of the pigments of a painting on a copper support. On the other hand, it was to enrich the literature
related to the study of paintings on metal supports, since few related studies are available despite the
relatively large number of such 16th and 17th century paintings from Italy and Northern Europe. The
results of the analysis showed a copper support with a base layer of gypsum mixed with ochre earths.
Atop this layer is a sketch with lead white in the lighter areas and bone black in the darker shadow
areas, suggesting that the artist performed a preliminary study of the luminosity of the scene. Finally,
the upper or pictorial layer consists of a mix of pigments with some lead white to lower saturation
and increase lightness, particularly evident in the flesh tones. The resulting palette thus includes
lead white, vermilion, bone black, Naples yellow, and lazurite pigments. These results are compared
to Veroneseâs other paintings, as well as to those of certain contemporary artists, and the use of the
resulting pigments in 16th and 17th century Italian painting techniques is discussedProject FEDER/Junta
de AndalucĂa-ConsejerĂa de EconomĂa y Conocimiento/A-HUM-164-UGR18Research group
FQM-338Analytical Techniques Unit EQC2018-004952-
Unmixing and pigment identification using visible and short-wavelength infrared: Reflectance vs logarithm reflectance hyperspaces
Hyperspectral imaging has recently consolidated as a useful technique for pigment mapping and identification, although it is commonly supported by additional non-invasive analytical methods. Since it is relatively rare to find pure pigments in aged paintings, spectral unmixing can be helpful in facilitating pigment identification if suitable mixing models and endmember extraction procedures are chosen. In this study, a subtractive mixing model is assumed, and two approaches are compared for endmember extraction: one based on a linear mixture model, and the other, nonlinear and Deep-Learning based. Two spectral hyperspaces are used: the spectral reflectance (R hyperspace) and the -log(R) hyperspace, for which the subtractive model becomes additive. The performance of unmixing is evaluated by the similarity of the estimated reflectance to the measured data, and pigment identification accuracy. Two spectral ranges (400 to 1000 nm and 900 to 1700 nm) and two objects (a laboratory sample and an aged painting, both on copper) are tested. The main conclusion is that unmixing in the -log(R) hyperspace with a linear mixing model is better than for the non-linear model in R hyperspace, and that pigment identification is generally better in R hyperspace, improving by merging the results in both spectral ranges.MCIN/AEI/10.13039/501100011033 and by âERDF A way of making Europeâ [grant number PID2021-124446NB-100]Ministry of Universities (Spain) [grant number FPU2020-05532
Complexonas de la antropurpurina y de la quinizarina : aplicaciones analĂticas inorgĂĄnicas
Univ. Granada, Departamento de QuĂmica AnalĂtica. LeĂda el 08-07-197
Determination of acrinathrin in water samples by micro liquid-liquid extraction and gas chromatography mass spectrometry
Acrinathrin [(S)-a-cyano-3-phenoxybenzyl
(Z)-(1R,3S)-2,2-dimethyl-3-[2-(2,2,2-trifluoro-l-trifluoromethyl-ethoxycarbonyl)vinyl]cyclopropanecarboxylate]
is an acaricide insecticide pyrethroid acting through contact and ingestion by such insects as phytophagous mites on citrus, cotton, fruit, hops, ornamentals, soyabeans, tobacco, vegetables, vines and greenhouse crops. Its half life in water is longer than other pesticides even under photolysis by natural sunlight. Acrinathrin is manufactured by Roussel Uclaf under the tradename of Rufast (15% acrinathrin w/v). A
method for the determination of acrinathrin residue in vegetables by gas chromatography was proposed by Fernandez-Alba using electron capture detector (GC-ECD), with a determination limit of 0.001 mg kg-1. Here, we propose a method for the determination of acrinathrin in ground and sea water based in a hexane micro liquid-liquid extraction, a technique which has also been applied to the detection of some pyretroids and endosulfans in water.This study was funded by the ComisiĂłn Interministerial de Ciencia y TecnologĂa (CICYT) project AMB-94-0776 (Spain)
Determination of trace aluminum in natural waters by ion exchanger fluorometry
Morin (2âČ, 3, 4âČ, 5, 7-pentahydroxyflavone) has been used as a ligand in the fluorometric microdetermination of aluminum at the sub-ÎŒgl-1 level. A method has been developed which is based on ion exchanger fluorometry (IEF). The 1:1 aluminum-morin complex is fixed on a dextran-type cationic exchanger, and the fluorescence of the gel, packed on a 1-mm quartz cell, is measured directly using a solid-surface attachment. The concentration for the method ranges between 0.4 and 1.6ÎŒgl-1, although this can be diminished by increasing the sample volume. The method has been successfully applied to the determination of aluminum in natural water and offers several advantages in comparison with solution methods.This study was supported by the DirecciĂłn General de Universidades e InvestigaciĂłn de la Junta de AndalucĂa (Spain), project n. 0010.9
Patrones quĂmicos monocloro, dicloro y tricloro derivados del bisfenol A
NĂșmero de solicitud: 200002432Se describe un mĂ©todo para la sĂntesis y purificaciĂłn de los derivados monoclorado, diclorado y triclorado de Bisfenol A. El mĂ©todo consiste en la cloraciĂłn del Bisfenol A y posterior separaciĂłn de los compuestos mediante cromatografĂa. Los patrones se identifican de forma unĂvoca presentando una pureza superior al 99,99 %. La disponibilidad de estos compuestos es de gran interĂ©s para los laboratorios de control y anĂĄlisis quĂmico, fisioquĂmico y toxicolĂłgico con objeto de poder determinar estos compuestos en muestras de interĂ©s ambiental, alimentario, cliĂnico industrial y legal
Determination of ultra-traces of anthracene in water samples by solid-phase spectrofluorometry
A rapid method for the determination of anthracene ultratraces in water by solid-phase fluorometry is described.Anthracene is fixed on C-18 silica to give fluorescence at λex=357nm and λex=405nm wavelengths. An anthracene-silica-gel system packed in a 1mm quartz cell was measured directly using a solid-surface attachment. The applicable concentration range was 50-1000ng dm-3 with a relative standard deviation of 0.7% and a detection limit of 21ng dm-3. The method was applied to the determination of anthracene in natural, tap and seawater samples. The recoveries were 100, 105 and 110%, respectively. The method is very simple and more sensitive than other methods described in the literature