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The quantification of Cr (VI) in the cement matrix is highly important, given the possibility of suffering illnesses including dermatitis, induced nasal carcinoma, and DNA damage produced by inhalation of and/or direct contact with this substance by construction workers. This study presents an analytical validation of the determination of water-soluble Cr (VI) using Ultraviolet–Visible Spectroscopy (UV–Vis) with 1.5-diphenylcarbazide. To do so, different performance characteristics were determined: working interval, analytical sensitivity, linearity, limits of detection (LOD) and quantification (LOQ), as well as measurement uncertainty, in order to provide better metrological information about the performance of this method. The study also focused on evaluating the impact of use of different types of standard sands (ASTM C-778 and CEN) for preparing mortar cement and extracting water soluble Cr (VI) present in the cement. For this purpose, two cements with different concentrations (2.01 ± 0.21 and 0.75 ± 0.09 mg-kg−1) of Cr (IV) were created to evaluate extraction using three types of treatments: oxidized with potassium peroxidisulfite, non-oxidized, and an alternative method using cement paste. It was observed that mortar cement using ASTM C-778 sand tends to underestimate Cr (IV) content when concentrations are below 0.8 mg kg−1, while at higher concentrations of ~2.0 mg kg−1 it does not generate different results compared to those obtained using mortar cement made with CEN-standard sand. An alternative method called "paste extraction" also showed statistically comparable results with respect to standard mortar for both concentration levels evaluated. Finally, samples of cement marketed in Costa Rica were analyzed using different types of water soluble Cr (IV) extraction methods. The results show concentrations between 0.70 ± 0.13 mg kg−1 and 1.30 ± 0.13 mg kg−1, demonstrating that they comply with the limits established by international standards and national regulations in Costa Rica. [Display omitted] • Method validation and robustness study in the UNE-EN-196-10 method were performed and discussed. • Reliability of the UNE-EN-196-10 using sands with different composition and granulometry were evaluated. • Measurement uncertainty (Bottom-up) for three different extraction methods for water-soluble Cr (VI) in cement was estimated. • Content of water-soluble Cr (VI) in hydraulic cement commercialized in Costa Rica was quantified. [ABSTRACT FROM AUTHOR]

Establishing and understanding large format paintings are key to provide accurate information about the artist's palette and developing conservation strategies. Therefore, investigating the artworks of a population offers insight into its culture, history and origins which reveals individual and collective identity through cultural heritage worldwide. Particularly, the ceiling of the Foyer at the National Theatre of Costa Rica (Central America) is decorated with three large format paintings from the nineteenth century made by the Italian painter Vespasiano Bignami. The paintings are known as La Poesía, La Música and La Danza (The Poetry, the Music and The Dance) and have undergone restorations in the past. However, their state of conservation is unknown and thus demands accurate scientific examination in order to document their status and the extent of undocumented previous restoration work. To overcome those issues, we propose the application of a combination of non-invasive and in-situ techniques to carry out a qualitative assessment of the pigments and actual state of conservation. Here, we employed technical photography in the visible and near infrared regions, using panoramic stitching techniques in order to obtain high resolution images of the very large artworks. Several conservation problems were observed such as: detachment of pigments, cracks, stains, and sections with undocumented restorations. In the IR and False Colour Infrared images we observed a very conspicuous behaviour of the red pigment used in the three paintings. Particular areas with the red pigment were fluorescent, and by means of ultraviolet fluorescence imaging we identified the pigment as through its red-coral fluorescence as Madder Lake, by comparison to a historical pigments reference palette. Measurements in five different red pigmented zones using UV–Vis spectroscopy in The Music show bands in the (550–650) nm region. A Lorentz Model nonlinear curve fit to the bands allowed us to correlate the fluorescent pigment in the paintings of Vespasiano Bignami with Madder Lake. [ABSTRACT FROM AUTHOR]