Chromatographic and spectroscopic identification and recognition of ammoniacal cochineal dyes and pigments

Chieli, Annalisa; Sanyova, Jana; Doherty, Brenda; Brunetti, Brunetto Giovanni; Miliani, Costanza

doi:10.1016/j.saa.2016.03.007

Cited by 27 publications

(8 citation statements)

References 24 publications

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“…The analysis of the state of degradation of inorganic pigments is possible by using a combination of several techniques such as X-ray diffraction (XRD) and Xray fluorescence (XRF) [4]. On the other hand, the characterization of organic pigments in many cases is more complex due to their lower stability compared to the inorganic compounds, and requires a combination of chromatography, mass spectrometric techniques and a range of vibrational spectroscopic techniques [5][6][7][8]. The identification and characterization of organic pigments in paintings is rendered even more difficult because organic lakes are often light sensitive materials [9,10].…”

Section: Introductionmentioning

confidence: 99%

Protecting and stimulating effect on the degradation of eosin lakes. Part 1: Lead white and cobalt blue

Álvarez‐Martín

Janssens

2018

Microchemical Journal

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An important problem encountered during the preservation of paintings and other artworks is the fading of the original colors due to exposure of the colorants to light. This fact is clearly evidenced in some of Vincent Van Gogh's paintings in which an organic red, eosin or geranium lake, is present.The identification of eosin and the characterization of its degradation products in paintings represents a challenge because of (i) the generally low concentration of the pigment remaining after an aging period of ca 100 years, (ii) the scarcity of the paint micro samples available for analysis and the difficulty of obtaining additional ones and (iii) the complexity of the degradation behavior of eosin when it is mixed with organic or inorganic pigments, binding media or varnish.

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Section: Introductionmentioning

confidence: 99%

Protecting and stimulating effect on the degradation of eosin lakes. Part 1: Lead white and cobalt blue

Álvarez‐Martín

Janssens

2018

Microchemical Journal

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“…Whenever sampling has been permitted, analytical pyrolysis coupled with gas chromatography-mass spectrometry (Py-GC/MS) [1,[29][30][31][32] has been successfully applied. Direct temperature mass spectrometry (DTMS) [25,33,34] and laser desorption mass spectrometry (LDMS) [34,35] have also been used, but have not yielded positive identification when isomers are present, which is often the case when organic pigments are concerned.…”

Section: Introductionmentioning

confidence: 99%

HPLC-DAD and HPLC-ESI-Q-ToF characterisation of early 20th century lake and organic pigments from Lefranc archives

et al. 2017

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The characterisation of atelier materials and of the historical commercial formulation of paint materials has recently gained new interest in the field of conservation science applied to modern and contemporary art, since modern paint materials are subjected to peculiar and often unpredictable degradation and fading processes. Assessing the composition of the original materials purchased by artists can guide not only their identification in works of art, but also their restoration and conservation. Advances in characterisation methods and models for data interpretation are particularly important in studying organic coloring materials in the transition period corresponding to the late 19th-early 20th century, when many such variants or combinations were hypothetically possible in their formulations. There is thus a need for reliable databases of materials introduced in that period and for gaining chemical knowledge at a molecular level related to modern organic pigments, by state-of-the-art protocols. This paper reports on the results of a study on 44 samples of historical colorants in powder and paint tubes, containing both lake pigments and synthetic organic pigments dating from 1890 to 1926. The samples were collected at the Lefranc Archive in Le Mans (France) as a part of Project Futurahma "From Futurism to Classicism (1910Classicism ( -1922. Research, Art History and Material Analysis", (FIRB2012, Italian Ministry of University and Research), and were investigated using an analytical approach based on chromatographic and mass spectrometric techniques. The focus of the chemical analyses was to reveal the composition of the historical organic lake pigments including minor components, to discriminate between different recipes for the extraction of chromophore-containing molecules from the raw materials, and ultimately to distinguish between different formulations and recipes. High performance liquid chromatography (HPLC) with diode array detector (DAD) or electrospray-Quadrupole-Time of Flight tandem mass spectrometry detector (ESI-Q-ToF) were chosen given their considerable capacity to identify such complex and widespread organic materials. Although the inorganic components of the pigments were not taken into account in this survey, the specific molecular profiles provided invaluable information on the extraction procedures or synthetic strategy followed by the different producers, at different times. For instance, the use of Kopp's purpurin and garancine was highlighted, and synthetic by-products were identified. The results provided evidence that the addition of synthetic organic pigments to paint mixtures started from 1910 onwards, but they also suggest that in the formulation of high quality (surfin) colorants, natural products were still preferred. Moreover, in one of the samples the use of murexide as the colouring material was confirmed. This paper presents the first systematic and comprehensive survey on organic lakes and pigments belonging to an historical archive, by both HPLC-DAD and HPLC-ES...

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“…Analyses of these samples by HPLC‐DAD showed the presence of a chromatographic peak related to the extraction of the dyestuffs from the insect in the presence of an ammonia containing solution, possibly indicative of the formation of acid stable carmine. Highlighted in historical references since 1867, this semi‐synthetic is of current interest for diagnostic purposes as a paint and dye in the cultural heritage domain although specific bands by Raman/SER spectroscopy are not entirely diagnostic here likely due to the presence of a further dye as discussed in the next section. Interestingly, however, is the fact that following this preparation, the Lefranc scientists subsequently returned to the traditional alum complexed carminic acid version as in F18, dated 1910.…”

Section: Resultsmentioning

confidence: 99%

Micro‐Raman and SER spectroscopy to unfold Lefranc's early organic pigment formulations

Gabrieli

Miliani

Degano

et al. 2016

J Raman Spectroscopy

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The introduction of synthetic dyes and pigments into commerce in the late 19th century was a stimulating time for experimental scientists in their laboratory formulations and for artists in their usage. Nowadays, the period of pioneering syntheses and employment of synthetic organic colouring materials is highly intriguing for scientific research and for conservation purposes in heritage science. In this work, a combination of spectroscopic and chromatographic methods has permitted the elucidation of the chemical composition of 16 early synthetic organic pigment powders from the Lefranc experimental laboratory collection dating 1890-1914. It can be hypothesized that the most successful of these formulations could have been finalized in paint tubes and released onto the market, meaning that they may even be found in artworks from the same period. Specifically, information from this crucial period of transition from the exclusive use of natural dyes/colourants (such as neoflavonoids and plant and insect anthraquinones) to the introduction of their synthetic counterparts (such as synthetic alizarin and purpurin, and acid stable cochineal, together with monoazo and diazo pigments) is confirmed through Raman/surface-enhanced Raman spectroscopy and high-performance liquid chromatography with diode array detection. By means of X-ray fluorescence and mid-Fourier transform infrared spectroscopy, a combination of traditional and modern inorganic substrates has been identified (alum, kaolin, barium sulfate and metallic salts), while Raman has provided additional data regarding the possible complexation of these pigments in the form of lakes

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Chromatographic and spectroscopic identification and recognition of ammoniacal cochineal dyes and pigments

Cited by 27 publications

References 24 publications

Protecting and stimulating effect on the degradation of eosin lakes. Part 1: Lead white and cobalt blue

Protecting and stimulating effect on the degradation of eosin lakes. Part 1: Lead white and cobalt blue

HPLC-DAD and HPLC-ESI-Q-ToF characterisation of early 20th century lake and organic pigments from Lefranc archives

Micro‐Raman and SER spectroscopy to unfold Lefranc's early organic pigment formulations

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