A combination of invasive and non-invasive techniques for the study of the palette and painting structure of a copy of Raphael’s Transfguration of Christ

We thank the owner of the painting Mr. F. Fernandez Fábregas 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 A‐HUM‐164‐UGR18 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, SEM–EDX, and performed the µRS and µATR-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 Herit‑ 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 con‑ 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 Profes‑ 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, SEM–EDX; 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 investigación FEDER / Junta de Andalucía-Consejería de Economía y Conocimiento / A ‐ HUM ‐ 164 ‐ UGR18

Non-Invasive Study of the Pigments of a Painting on Copper with the Inscription “Boceto di Pablo Veronese” on the Back

The palette used on a small painting on copper support, with the inscription “Boceto di Pablo Veronese” 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 Veronese’s 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 Andalucía-Consejería de Economía 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 “ERDF A way of making Europe” [grant number PID2021-124446NB-100]Ministry of Universities (Spain) [grant number FPU2020-05532

Complexonas de la antropurpurina y de la quinizarina : aplicaciones analíticas inorgánicas

Univ. Granada, Departamento de Química Analítica. Leída 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 Comisión Interministerial de Ciencia y Tecnología (CICYT) project AMB-94-0776 (Spain)

Determination of trace aluminum in natural waters by ion exchanger fluorometry

Morin (2′, 3, 4′, 5, 7-pentahydroxyflavone) has been used as a ligand in the fluorometric microdetermination of aluminum at the sub-μgl-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 1.6μgl-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 Dirección General de Universidades e Investigación de la Junta de Andalucía (Spain), project n. 0010.9

Patrones químicos monocloro, dicloro y tricloro derivados del bisfenol A

Número de solicitud: 200002432Se describe un método para la síntesis y purificación de los derivados monoclorado, diclorado y triclorado de Bisfenol A. El método consiste en la cloración del Bisfenol A y posterior separación de los compuestos mediante cromatografía. Los patrones se identifican de forma unívoca presentando una pureza superior al 99,99 %. La disponibilidad de estos compuestos es de gran interés para los laboratorios de control y análisis químico, fisioquímico y toxicológico con objeto de poder determinar estos compuestos en muestras de interés ambiental, alimentario, cliínico 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