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Precise knowledge of the palette employed by historic painters is fundamental to preserving their works of art and can help pinpoint the period in which their paintings were created, their provenance and au- thorship. Raman and IR spectroscopy is successful in identifying pigments via their molecular spectrum, nevertheless, to distinguish the pigments in a binary mixture is challenging, particularly when the mixed pigments are the same colour and Cu-containing. This is precisely the aim of the current research: to evaluate the effectiveness of the molecular spectroscopy techniques μRS and μFTIR-ATR to discriminate binary mixtures of three green pigments, all containing copper, specifically copper resinate, malachite and verdigris. To that end, two sets of model samples were prepared with pure pigments and their bi- nary mixtures in variable weight concentrations from 20% to 80% for each component. The 15 model samples obtained were mixed with linseed oil in the fixed proportion of 3:1 (w/w) of powdered pigment to binder and spread in a homogeneous layer on a support of commercial grade canvas. Five replicates of μFTIR-ATR and μRS spectra, respectively, were recorded after 0 h, 24 h, 48 h, 72 h and 144 h of exposure within the controlled conditions of a climatic chamber. The aim is to establish the minimum percentage of a Cu-containing pigment in a binary mixture that can be detected by μRS and/or μFTIR-ATR spec- troscopy. The product of this ample study is a database of the spectroscopic signature of each pigment in the specific mixtures (in the given proportions and artificial ageing times) for reference purposes in the study of the green areas of selected masterpieces. The oil paintings used in the research ( The Nativity, The Visitation , and The Assumption ) are of Alonso Cano’s work, a well-known artist of the Spanish Golden Age (the Siglo de Oro in Spanish). With this study, the knowledge of the mixture of green pigments em- ployed in Cano’s palette was expanded, making considerable progress in the ambitious National Projects in which our Research Group, ever since 2003, has been attempting to understand Cano’s technique., University of Granada/CBUA, research group FQM-338, research group HUM-839

Alonso Cano is considered one of the most original and brilliant artists from the Spanish Golden Age (known in Spanish as Siglo de Oro), a period of flourishing in arts and literature. He was also ...

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 samples, All 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-P, Proyecto de investigación FEDER / Junta de Andalucía-Consejería de Economía y Conocimiento / A ‐ HUM ‐ 164 ‐ UGR18.

One of the analytical difficulties that may appear in the analytical process of the archaeological materials is related to the complexity of matrices. In this sense, the abundant content of lipids in archaeological degraded material makes the analysis of polyphenols much more problematic. In addition, phenolic compounds with a low-molecular weight might be present at trace level or even not be present in ancient artefacts. In this study, the advantages of gas chromatography–mass spectrometry in selected ion monitoring mode (GC–MS-SIM) for the analysis of wine biomarkers, tartaric and cinnamic acids, preserved in archaeological potsherd found in a votive deposit from the Iberian period in Granada (Spain) are presented. This will contribute to a greater understanding of the consumption of fermented beverages offered in votive rituals in Southern Spain during the Iberian period. To our knowledge, this is the first time that GC–MS-SIM technique is used to identify low concentrations of these polyphenolic acids in archaeological residues. In addition, the GC–MS-SCAN and gas chromatography–combustion-isotope ratio mass spectrometry (GC–C–IRMS) analysis revealed the presence of animal fats and vegetable oils mixed with wax and conifer resin preserved in the Iberian glasses. The correlation between organic compounds identified in the residues (short and odd-chain fatty acids (C9:0 to C12:0, C17:0 and C19:0), palmitic, stearic, azelaic, oleic, lignoceric and dehydroabietic acids and long-chain odd-numbered alkanes) and its possible origin are also discussed.

This paper seeks to reconstruct everyday human activities in a Bronze Age Argaric site in southeastern Spain. We used an integrated multi-analytical approach to study residues extracted from 5 ceramic pieces and 3 soil samples. The results of these analyses were complemented with archaeological interpretations to produce the first findings on domestic activities four millennia ago at the Penalosa settlement in Jaen, Spain. The bands observed in FTIR and ATR–FTIR spectra of the archaeological residues showed a peak assignment that confirmed the silicate components of the clay as raw material and the presence of organic matter. The amorphous organic materials were analyzed by GC–MS, HRMS and GC–C–IRMS, and the mineral residues by non-invasive portable X-ray fluorescence (pXRF). We identified α,ω-dicarboxylic and ω-(o-alkylphenyl) alkanoic acids produced by oxidative degradation of unsaturated fatty acids, as well as monocarboxylic acids, n-alkanes, diterpenoid acids, cholesterol, dyes and chemical grape markers. Assignments were based on lipid profile, fatty acid ratios and the δ13C values of C16:0 and C18:0. The results are consistent with the presence of tissues from ruminant (ovine or bovine) and non-ruminant (swine and equine) animals, vegetable oils, waxes, conifer resin and grape seeds. The presence of fish-based fats was suggested in one of the residues. Our evidence also suggests that grape juice or wine may have been consumed at this Bronze Age site. As far as we know this is the first investigation of the organic residues absorbed into an Argaric goblet used in a domestic situation.

The identification of proteinaceous materials in paint constituents provides very valuable information regarding the techniques used by the painter and the most suitable procedures for conserving and restoring their works. Although the analysis of proteinaceous materials is nowadays a common task when dealing with works of art, the reliable detection and identification of protein traces is still complicated, particularly when very small samples can be taken that may contain a mixture of different organic materials (oils, waxes, resins, gums etc.). We therefore proposed a proteomic approach to investigate protein materials in paintings at trace levels in order to obtain a better understanding of the painter's technique. After trypsin digestion of the paint samples, mass spectra were obtained by matrix-assisted laser desorption and ionization time of flight mass spectrometry (MALDI-TOF-MS) and they were compared with the Mascot database and with theoretical digested proteins. This study contributes to the knowledge about the technique used by Alonso Cano (Granada, Spain, 1601–1667), one of the most original and brilliant artists from the Spanish Golden Age (17th century), in the series called the Life of the Virgin (six paintings), part of the iconographic program about the life of the Virgin Mary, nowadays seen in the main chapel of Granada Cathedral. The objective of the present study was to test the use of proteinaceous material, mainly egg yolk, in the paint used by Cano, as suggested in previous research, although this would have been unusual at that time when most artists used oil paints. Based on the results of the analysis here presented, the use of protein in the binding media can most likely be excluded.

A painting bearing the signature “Picasso” was investigated and its components – pigments and binders – were characterised using micro-Raman spectroscopy (mRS) combined with other analytical techniques such as Scanning Electron Microscopy with Energy Dispersive X-ray analysis (SEM/EDX), Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Gas Chromatography-Mass Spectrometry (GC-MS). We identified the pigments in order to assess chronological inconsistency (anachronistic pigments) with the work of the Spanish artist Pablo Picasso (1881–1973) by means of in situ and cross-section analyses by mRS. Using mRS we identified the pigments ‘phthalocyanine blue’, ‘phthalocyanine green’, ‘pyrazolone orange’, ‘anatase’ and ‘rutile’ (titanium dioxide). These results were corroborated by SEM/EDX elemental analysis, which detected Ba, S and Zn among others, so prompting discussion about the use of ready-mixed house paints (Ripolin®). The ground layer was also investigated by mRS, which confirmed the use of rutile (titanium dioxide), calcite and phyllosilicates (Al, Fe). mRS on the white area identified the binding media as beeswax, the most important wax used in art. ATR-FTIR and GC-MS analysis support the presence of a wax and an oil–resin mixture as the binder, described in previous research as being used by Picasso. All the artist materials identified were widely used in art at the beginning of the twentieth century according to the available bibliography and are therefore consistent with the Picasso era. To the best of our knowledge this is the first attempt to investigate a painting related to Picasso using the combination of analytical techniques proposed here.

The analysis of the organic residues in archaeological pottery usually involves the use chromatography and mass spectrometry techniques. The identification of organic compounds processed in archaeological vessels, which generally degrade over archaeological timescales, provides insights about their origin and uses of the vessels. This paper provides an advance of archaeometric characterization of the organic residues in seventeen pottery vessels from the end of the 4th millennium BCE found in the Virues-Martinez cave (Granada, Spain), using gas chromatography–mass spectrometry (GC–MS), gas chromatography-isotope ratio mass spectrometry (GC-C-IRMS), and ultra-performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS). To our knowledge this is the first study on the use of UPLC-HRMS on archaeological residues. Despite the fact that the identification of plant remains continues to be elusive, this study demonstrates the potential usefulness of UPLC-HRMS technique to study the polar fraction of plant residues, thus allowing us to formulate more specific hypotheses about the vegetal compounds that have survived in association with the pottery vessels (erucamide, matricarin, piptamine, piceatannol). Our results indicate that the occupants of the cave used the vessels to process plant materials and also degraded animal fats (ruminant fat) and it is very likely that the vessels were used for a variety of purposes, with accumulation of by-products over time, and were not made exclusively for funerary practices. The δ13C values C16:0 and C18:0 fatty acids obtained open a debate on the consumption of dairy compounds in the Iberian Peninsula during the end of the Neolithic and beginning of the Copper Age.

The authors would like to thank Mr. Francisco Fernández Fábregas, owner of the Transfiguration of Christ for allowing us the privilege of studying this painting. We also acknowledge the collaboration of Angela Tate., This paper presents a complete framework for capturing and processing hyperspectral reflectance images of artworks in situ, using a hyperspectral line scanner. These capturing systems are commonly used in laboratory conditions synchronized with scanning stages specifically designed for planar surfaces. However, when the intended application domain does not allow for image capture in these controlled conditions, achieving useful spectral reflectance image data can be a very challenging task (due to uncontrolled illumination, high-dynamic range (HDR) conditions in the scene, and the influence of chromatic aberration on the image quality, among other factors). We show, for the first time, all the necessary steps in the image capturing and post-processing in order to obtain high-quality HDR-based reflectance in the visible and near infrared, directly from the data captured by using a hyperspectral line scanner coupled to a rotating tripod. Our results show that the proposed method outperforms the normal capturing process in terms of dynamic range, color and spectral accuracy. To demonstrate the potential interest of this processing strategy for on-site analysis of artworks, we applied it to the study of a vintage copy of the famous painting “Transfiguration” by Raphael, as well as a facsimile of “The Golden Haggadah” from the British Library of London. The second piece has been studied for the identification of highly reflective gold-foil covered areas., Spanish Ministry of Economy and Competitiveness, DPI2015-64571-R, ECQM2018-004952-P

SIMCA pattern recognition is used with amino acid chromatographic profiles in a large homemade collection of natural protein binders obtained following old recipes traditionally used by painters and considered here as the standard of classification. An initial cluster analysis of the full dataset made it possible to distinguish three main classes of protein binders: albumin, casein and collagen-like substances. An additional iterative study of each class revealed a new subclass, i.e., glair, yolk and whole egg for the albumin class; goat, sheep and cow for the casein class; and mammals and fish for the collagen class. Optimized SIMCA models for each class and subclass were obtained with good results in terms of sensitivity (90–100%), specificity (73–100%) and interclass distance (>1.4), providing identification of the protein binder present in a set of samples of different origins such as natural products, commercial binders and works of art considered cultural heritage.

This work explores the application of chemometric techniques to Raman spectra to study aged lipidic paint binders. These binders, commonly known as drying oils, were widely used by artists throughout history both individually and in mixtures. We prepared various model samples of the pure binders (linseed, poppy-seed and walnut oils and egg yolk) and of binary mixtures thereof. These model samples were left to age naturally for six years and further characterized by Raman spectroscopy. A comparative study of the Raman spectral features before and after ageing process was carried out. This showed changes mainly in the bands located at 1267, 1655 and 3011 cm–1, which correspond to vibrations in cis double bonds. Multivariate analysis was performed by applying principal component analysis and partial least-squares discriminant analysis on the corresponding Raman spectra to test whether spectral differences allowed samples to be distinguished on the basis of their composition. The CH stretching region was found to be especially useful for discrimination between the different binders. Furthermore, good sensitivity and specificity were found in the discriminant analysis particularly for the identification of binders containing egg yolk. The results of these multivariate analyses demonstrated the potential use of both chemometric approaches in the field of Cultural Heritage for drying oil characterization and identification, and also for gaining a deeper insight into the ageing process. Copyright © 2011 John Wiley & Sons, Ltd.

This work seeks to identify the slight changes in the characteristic CH stretching region (3100–2800 cm−1) of a protein-based binder and fatty acid esters from egg yolk, which may occur in complex paint samples due to the presence of particular pigments. To date, this protein region—where historic pigments do not show characteristic Raman bands—has not been used to identify possible interactions between painting materials, in spite of its potential due to the mentioned feature. This study is based on the investigation of pure egg yolk model samples and tempera model samples prepared by mixing this binder with some historic pigments (cinnabar, raw Sienna, lead white, gypsum, calcite, azurite, lapis lazuli and smalt) as binary samples. All samples were analyzed in this region by Raman microscopy (RM) coupled with principal component analysis (PCA) for three color groups (red, white and blue) separately. The results show relevant spectral changes in the CH stretching region of amino acids and polyunsaturated fatty acids esters of the egg yolk binder, particularly in the azurite, lead white and gypsum-based tempera samples. Lesser interactions were discerned in the tempera samples made with smalt, as well as shift in the region of polyunsaturated fatty acid esters of the egg yolk binder in the cinnabar and raw Sienna-based tempera paintings. No interactions were recognized between the egg yolk and the pigments calcite and lapis lazuli. The effectiveness of applying RM combined with PCA for identifying interaction processes between binders and pigments is demonstrated. Copyright © 2011 John Wiley & Sons, Ltd.

The correct identification of drying oils plays an essential role in providing an understanding of the conservation and deterioration of artistic materials in works of art. To this end, this work proposes the use of peak area ratios from fatty acids after ensuring that the linear responses of the detector are tested. A GC-MS method, previously reported in the literature, was revisited to its developed and validated in order to identify and quantify of eight fatty acids that are widely used as markers for drying oils in paintings, namely myristic acid (C(14:0)), palmitic acid (C(16:0)), stearic acid (C(18:0)), oleic acid (C(18:1)), linoleic acid (C(18:2)), suberic acid (2C(8)), azelaic acid, (2C(9)) and sebacic acid (2C(10)). The quaternary ammonium reagent m-(trifluoromethyl)phenyltrimethylammonium hydroxide (TMTFAH) was used for derivatization prior to GC-MS analysis of the oils. MS spectra were obtained for each methyl ester derivative of the fatty acids and the characteristic fragments were identified. The method was validated in terms of calibration functions, detection and quantification limits and reproducibility using the signal recorded in SIR mode, since two of the methyl derivatives were not totally separated in the chromatographic run. The proposed method was successfully applied to identify and characterise the most widely used drying oils (linseed oil, poppy seed oil and walnut oil) in the painting La Encarnación. This 17th century easel painting is located in the main chapel of the cathedral in Granada (Spain) and was painted by the well-known artist of the Spanish Golden Age, Alonso Cano (1601-1667).

The effects of a UV-accelerated ageing test on model samples of azurite glue tempera, pure azurite and pure rabbit glue, all elaborated according to medieval recipes, were studied. The color changes and modifications in composition and texture for both pure and mixed samples are shown and discussed. Special attention is given to the physico-chemical interactions occurring when azurite and glue are combined. Ageing effects on the model samples after up to 3000 h of UV irradiation were periodically analyzed by scanning electron microscopy (SEM) with X-ray energy dispersive spectrometer (EDS) microanalysis, X-ray diffraction (XRD), reflectance spectrophotometry and Fourier-transform infrared spectroscopy (FT-IR). Once the ageing process ended, a chemometric study using principal component analysis (PCA) of the FT-IR data was carried out independently for every model sample and for all the azurite-laden samples. Loadings from the significant principal components were analyzed to identify the FT-IR frequency (cm −1 ) involved in the degradation process. PCA proved capable of identifying significant changes in pure glue samples. Also this work showed the lack of photochemical effects of UV irradiation on both pure azurite samples and those mixed with glue, in agreement with the SEM-EDS, XRD and colorimetrics results. Nevertheless PCA revealed that the azurite FT-IR spectral variability decreased in the presence of glue, being more affected by exposure to the IR region between 2100 cm −1 and 3600 cm −1 , where the azurite band is located. In addition, PCA managed to separate the azurite/glue mixture samples from pure azurite samples.

This work explores the application of principal component analysis (PCA) on first-derivative Raman spectra to investigate historical tempera paint model samples. Various paint model samples were prepared containing pure blue pigments (azurite, lapis lazuli and smalt), pure red pigments (cinnabar, minium and raw Sienna), pure white pigments (lead white, chalk and gypsum), pure egg yolk as binder and tempera model samples obtained by mixing each of the pigments with the binder, and further characterized by Raman spectroscopy. The corresponding Raman spectra were used to apply PCA in order to test whether spectral differences allowed discrimination of samples based on their composition. Multivariate analyses were performed separately on three data matrices, one for each color, namely, white, blue and red, corresponding to the model samples, and all containing the spectral data of the binder model sample. Different pretreatments, that is log and derivative spectra, were performed on the spectra since no pattern distributions were obtained when the original Raman spectra were analyzed. Nevertheless, the multivariate analysis of the original Raman spectra was able to track alterations of sensitive pigments due to laser interaction. Results showed the excellent ability of PCA, when applied to the derived Raman spectra, to discriminate model samples according to their differing compositions in the three groups of model samples tested. This is the first attempt to use this approach in the field of cultural heritage and demonstrates the potential benefits for identifying historical pigments and binders for purposes of conservation and restoration. Copyright © 2010 John Wiley & Sons, Ltd.

The Carrera del Darro is a street within the city of Granada, Spain, which is emblematic owing to the architectural value of its buildings, to its significance for the urban structure of the city and to the implications it has for the surroundings of the Alhambra. Our study concerns the chemical analysis of the mural paintings on four facades, corresponding to numbers 23, 25, 27 and 29 of the Carrera del Darro. From the analysis of the mortar, it may be concluded that the composition is very similar, though not identical, in the four paintings studied: a limestone mortar. Ochre, white, black and red were used for the decoration of the four facades; green pigment was also observed in the second decoration of no. 29. The results of the morphological examination and EDX microanalysis of the paint samples are shown. By means of the thermogravimetric analysis we established the existence of an organically derived compound. After the existence of an oleaginous binder had been discounted by gas chromatography/mass spectrometry (GC/MS) analysis, we continued with the extraction and determination of proteins by spectrophotometry analysis, detecting low levels of proteins in the paint on the four facades analysed. The study was completed by evaluating the influence on the deterioration of the paintings by the possible surface presence of salts (such as nitrates or chlorides) and organic compounds.

A Spectrofluorimetric method for the determination of traces of bromide has been developed. The method is based on the bromination of fluorescein after bromide and hypochlorite form bromine, giving the less fluorescent eosin. The fluorescence decrease is used as the analytical signal. The calibration graph is linear over the range 10 to 80 μg/1. The detection limit is 3 μg/1 and the relative standard deviation 1.0%. The method has been satisfactorily applied to the determination of bromide in natural waters.

A method for the determination of traces of boron by first-derivative synchronous spectrofluorimetry is proposed. It is based on the formation of a fluorescent complex with chromotropic acid at pH 6.7. The constant wavelength difference chosen to optimize the determination is Δλ=λem−λex=24 nm. The range of application is between 2.0 and 20.0 μ/l of boron, the detection limit 0.4 μg/l and the relative standard deviation 3.2%. A study was made of the influence of several ions as potential interferents. The method has been satisfactorily applied to the determination of boron in plants, fertilizers and natural waters.

A revisitation of the well known chromatographic procedure for the determination of amino acids as phenylthiocarbamyl derivatives (PTC) is performed. The method was developed for a microbore column that it is more appropriate to our later aims, the characterization of proteinaceous binders present in microsamples coming from the Cultural Heritage field. Several variables relating to chromatographic aspects were studied such as the pH and temperature of the mobile phase, buffer and modifier (triethylamine) concentrations in mobile phase and the stability of PTC-derivatives in solution. The calibration function was studied in depth. To prevent the heteroscedastic behaviour that it is observed, we used the weighed least squares fitting as the best strategy among other normalizing transformations, such as square root and logarithmic functions. Finally, the proposed method showed results similar to the traditional method in terms of efficiency, runtime, LODs and other characteristics, but with two additional advantages: a lower mobile phase consumption and the possibility of working with a lower sample volume. The usefulness of proposed method is checked against easel painting samples of Pictorial Heritage.

This work presents a preliminary study on the ageing process of proteinaceous binder materials used in painting under UV light. With this aim, two sets of model samples were prepared: samples prepared using a single protein material and complex samples prepared in a similar way to the sequence of layers in a real painting from lowest to highest complexity (protein, drying oils, pigment and varnish). The study focuses on acquiring information about the possible degradation process of proteinaceous binders due to ageing and how this process be affected by the presence of characteristic non-proteinaceous painting materials, such as lipids from linseed oil, terpenic compounds from varnish and inorganic pigments. Samples simulated the accelerated ageing process, as did the UV light exposition. The FT-IR spectra were recorded after 100, 500, 1000 and 1500 h of exposition. The study of the accelerated ageing process was performed by means of principal component analysis (PCA) using the FT-IR spectra obtained. Loadings from the significant principal components were analysed to find the FT-IR frequency (cm(-1)) involved in the degradation process. The study showed the lack of any relevant modification on the proteins in the single model samples. On the contrary, the complex model samples showed the ageing process. The accelerated ageing process can be explained by a principal component from PCA. The most affected IR region was 2900-3600 cm(-1), where the amide band was included.

In this paper, we performed a comparison between commonly used strategies amino acid ratios (Aa ratios), two-dimensional ratio plots (2D-Plot) and statistical correlation factor (SCF) and a classification technique, soft independent modelling of class analogy (SIMCA), to identify protein binders present in old artwork samples. To do this, we used a natural standard collection of proteinaceous binders prepared in our laboratory using old recipes and eleven samples coming from Cultural Heritage, such as mural and easel paintings, manuscripts and polychrome sculptures from the 15-18th centuries. Protein binder samples were hydrolyzed and their constitutive amino acids were determined as PITC-derivatives using HPLC-DAD. Amino acid profile data were used to perform the comparison between the four different strategies mentioned above. Traditional strategies can lead to ambiguous or non-conclusive results. With SIMCA, it is possible to provide a more robust and less subjective identification knowing the confidence level of identification. As a standard, we used proteinaceous albumin (whole egg, yolk and glair); casein (goat, cow and sheep) and collagen (mammalian and fish). The process results in a more robust understanding of proteinaceous binding media in old artworks that makes it possible to distinguish them according to their origin.

A method for the simultaneous determination of aluminium and beryllium in mixtures by first-deravative synchronous solid-phase spectrofluorimetry has been developed. Aluminium and beryllium reacted with morin to give fluorescent complexes, which were fixed on a dextran-type resin. The fluoresnce of the resin, packed in a 1-mm silica cell, was measured directly with a solid-surface attachment. The constant wavelength difference chosen to optimize the determination was Deltalambda = lambda(em) = 75 nm. Aluminium was measured at lambda(em)lambda = 445/520 nm and beryllium at lambda(em)lambda(em) = 430/505 nm. The range of application is between 0.5 and 5.0 ng/ml for both aluminium and beryllium. The accuracy and precision of the method are reported. The method has been successfully applied to the determination of aluminium and beryllium in synthetic mixtures and natural waters.

The ‘Corral del Carbon’ in Granada was built during the Nasrid period (fourteenth century) as a combined warehouse and inn. Saved from demolition early this century, it was acquired by the state in...

A method for the determination of trace amounts of beryllium has been developed, based on ion-exchange spectrofluorimetry. Beryllium reacts with morin to give a highly fluorescent complex, which was fixed on a dextran-type anion-exchange resin. The fluorescence of the resin, packed in a 1-mm quartz cell, was measured directly using a solid-surface attachment. The concentration range of the method is 0.10–0.70 µg l–1, the relative standard deviation 1.4% and the detection limit 0.02 µg l–1. The method was applied to the determination of beryllium in natural waters. The aluminium and calcium levels can be determined first in order to reduce their interfering effect. The proposed method is more sensitive and selective than that using morin alone.

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)