Analytische Chemie
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This work highlights the rediscovery of the technique of reverse glass painting by the artists of the “Blaue Reiter” collective in the early 20th-century and focusses particularly on the role of Wassily Kandinsky (1866–1944). Kandinsky created more than 70 reverse paintings on glass and showed several of them in exhibitions together with paintings on canvas and cardboard, implying a coequal importance of these techniques. Four of his early (1911–1914) reverse glass paintings (Auferstehung, Allerheiligen II, Rudern, Apokalyptischer Reiter II) were selected for investigation and their iconography, painting techniques and painting materials were examined. Two paintings were executed on so-called cathedral glass, revealing a “hammered surface”, whereas Kandinsky used a corrugated glass panel for Rudern. A multi-analytical, non-invasive approach [X-ray fluorescence (XRF), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), VIS spectroscopy (VIS), Raman spectroscopy] was taken to identify the pigments and classify the binding media. The results reveal a broad palette of materials. Several pigments like lead white, zinc white, Strontium yellow, Prussian blue, viridian, cadmium yellow, ultramarine blue, cinnabar and carbon black were found in most of the four paintings. The use of the rare synthetic organic pigments PR60 and PB52 is discussed. In two works of art, cadmium carbonate is associated with cadmium yellow. The identification of aluminium foil along with tin foils in Rudern indicates an early use of this material for reverse glass paintings.
The objective of this study is to find out, to what extent the geochemical characteristics of lapis lazuli can be utilized in respect to its provenance. A wide range of variables is taken into consideration depending on the quantity of samples analysed from a specific geological region and the methods applied. In order to provide evidence, a multi-technique analytical approach using µXRF, ESEM, PGAA and PIXE is applied to samples from the most famous deposits of lapis lazuli. Special elements determined as fingerprints are compared in relation to the forming conditions obvious in textural features. The results and statistical output allow a differentiation that enables an optimized local classification of the blue stone. An absolute requirement for all geo-tracing performed on blue colored cultural objects of unknown provenance is awareness of the limits of analysis. The possible sources of lapis lazuli are tested by analysing the blue pigment used as paint on murals and ink on manuscripts from the Silk Road.
Draft standards for the determination of organic pollutants in the solid matter of environmental matrices such as sludge, treated biowaste and soil have been basically developed in the framework of the European standardization project HORIZONTAL. A research project financed by the German Federal Environment Agency was initiated to finalize some of these CEN standard drafts, since fully validated standard procedures are crucial for the evaluation of their reliability in the context of implementation in legislation on environmental health.
Approach: Appropriate test materials (< 2mm particle size) were prepared and homogenized from contaminated soils, sludge and treated biowaste containing polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), dioxins, furans and dioxin-like-PCB and served, along with reference solutions, as the basis for international interlaboratory comparisons. Performance data of three analytical standard procedures were obtained by the statistical evaluation of results received from 11 to 29 participants per test material.
Results: The overall variation coefficients of reproducibility (between-lab standard deviations) for the sum parameters were roughly between 10 and 35 %. The variation coefficients of repeatability (within-lab standard deviations) range between 3 % and 8 % and show no trend considering the substance groups or matrices.
The highest coefficients of reproducibility were found for the analysis of PAHs, which were between 26 and 35 %, depending on the matrix, whereas 7-17 % reproducibility was observed for toxicity equivalents (TEQ) comprising dioxins, furans and dl-PCB.
Conclusions: Overall, the results confirm that the procedures described in the Technical Specifications are fit for purpose for all three matrices and that the feasibility of the HORIZONTAL approach, to cover several matrices with one standard per analyte, was thereby proven.
The presented Humboldt Codices are from the early colonial period of Mexico and originate from different localities
1. typical indigen colors and mixtures:
cochineal (red), indigo (blue and green), carbon (black),
mangle, zacatlaxcalli, organic (brown, yellow)- critical!
2. colonial influence:
iron gall ink for writing
3. single fragments belong together:
are cut (fragments IX-XII),
from Mizquahuala distributed (VII, XIII, XIV, [XV]) (VII, XIII in Mexico, XIV in Paris)
A wide range of methods are used to estimate the plant-availability of soil phosphorus (P). Published research has shown that the diffusive gradients in thin films (DGT) technique has a superior correlation to plant-available P in soils compared to standard chemical extraction tests. In order to identify the plantavailable soil P species, we combined DGT with infrared and P K- and L2,3-edge X-ray adsorption near edge structure (XANES) spectroscopy. This was achieved by spectroscopically investigating the dried binding layer of DGT devices after soil deployment. All three spectroscopic methods were able to distinguish between different kinds of phosphates (poly-, trimeta-, pyro- and orthophosphate) on the DGT binding layer. However, infrared spectroscopy was most sensitive to distinguish between different types of adsorbed inorganic and organic phosphates. Furthermore, intermediates of the time-resolved hydrolysis of trimetaphosphate in soil could be analyzed.
A non-invasive methodological approach has been carried out to identify the pigments and classify the binding media of the reverse painting on glass Kreuzabnahme (1914/15) by Carlo Mense.
Mense was a member of the group Rhenish Expressionists around August Macke and got interested in the technique of painting on the reverse side of a glass panel. The studied painting indicates a remarkably painted reverse and front side, which creates a unique visual appearance of the glass. The applied noninvasive, spectroscopic approach includes X-ray fluorescence, VIS spectroscopy, Raman spectroscopy and diffuse reflectance infrared Fourier transform spectroscopy. The measurements revealed inorganic Pigments mixed with drying oil as binder. Together with common pigments, such as lead white, barium sulphate, bone black, cinnabar, chrome yellow, ochre, and viridian, an unusual additional material was found, Strontium white.
This work presents a technical investigation of two Chinese reverse glass paintings from the late 19th and early 20th centuries. A multi-analytical, non-invasive approach (X-ray fluorescence (XRF), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), Raman spectroscopy) was used to identify the pigments and classify the binding media. The results reveal a combined use of traditional Chinese and imported European materials. Several pigments like cinnabar, lead white, orpiment, carbon black and copper-arsenic green (probably emerald green) were found in both paintings; red lead, artificial ultramarine blue, Prussian blue and ochre appear in at least one of the paintings. The proof of limewash (calcite and small amounts of portlandite) as a backing layer in Yingying and Hongniang indicates that clamshell white was also used for reverse glass paintings. Drying oil was classified as a binding media in most areas of both paintings. However, the orange background of The Archer yielded prominent bands of both proteinaceous and fatty binder.