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Migliore Comunicazione Poster, Ilaria Serafini et al.,“Methodology for the identification of organic dyes used in tapestries”, Abstract “5th CMA4CH Mediterraneum Meeting”.
No full textFor dyeing yarns used in the production of tapestries, one of the most important source during the centuries was the root of madder (Rubia tinctorum L.). Madder root contains a large number of compounds characterized by anthraquinone structures, which give to the yarn a red hue. The main chromophore compounds, often in glycosylated form, are: 1,2-dihydroxy-anthraquinone (alizarin, orange colour); 1,2,4-trihydroxy- anthraquinone (purpurin, red colour); 1,2,4-trihydroxy-anthraquinone-3-carboxylic acid (pseudopurpurin, red-brownish colour; 1,2,3-trihydroxy-anthraquinone (anthragallol, orange colour).
During the dyeing process, however, also other types of molecules (not necessarily anthraquinones), present in the matrix, are fixed on the yarn. These substances may be involved in the aging process and their participation in the processes of degradation is currently under investigation. Experimentally it is in fact observed that some compounds show a faster degradation than the others. In order to establish an appropriate restoration, it is necessary to identify all the compounds involved and then clarify the mechanisms of degradation. In this work, it has carried out extraction of dyes from textile fibers coming from some tapestries in the Vatican Museums; extracts has been analysed by HPTLC, 1H-NMR and ESI-MS.
First, madder’s root extract has been obtained in the same conditions of dye bath. This extract has been studied through LC and both 1H-NMR. Fractions obtained were compared with extracts from historical yarns and “contemporary textiles” dyed according to original recipes. This comparison has been carried out through HPTLC. In this way, it highlighted which bands were present in madder’s roots and in the yarn’s extracts.
The most interesting samples were chromatographed through TLC technique and the resulting bands were extracted and solubilized in a 1:1 mixture of acetonitrile and 0.3% formic acid in water. Then, ESI-MS and ESI-MSn experiments were performed. Through this technique, we obtain the full spectrum with the value of m/z for every compound contained in a fraction and then we can fragment every single peak to clarify the structural profile of the same.
Specifically, we show here two examples of the use of ESI-MSn tecnique for the identification of hydroxy hydroxy-methyl anthraquinone and glycosyl asperulosidic acid
A new approach to the mild extraction of madder dyes from lake and textile
No full textIn this paper, we present a new alkaline mild extraction technique of madder dyes in lake and textile, based on the use of ammonia, in association with disodium EDTA. This method was developed in order to preserve the glycoside compounds fixed on the fiber or present in the lake. This new methodology was performed on samples of dyed textile and lake, prepared following the ancient recipes. At first, the extracts, obtained from these samples, were analyzed and characterized by 1D and 2D NMR (DOSY) and ESI-MS. In the second step, we evaluated the applicability and the efficiency of extraction on real samples of 1 mg, analyzed by HPLC–DAD and HPLC–MS. These analyses allow us to recognize the signals, referable to glycoside compounds, also in 1 mg samples. The new proposed method was compared with a commonly applied mild extraction method reported in literature (DMF–Na2EDTA method). Finally, the results obtained from the different analytical techniques applied allow us to conclude that the ammonia extracts of madder dyed yarn and lake are mainly composed of glycosylated anthraquinones, according to literature
Composizione per uso nella finitura, conservazione, restauro di manufatti
No full textThe present invention refers to the field of chemistry and more in particular to the field of preservation and restoration of 15 manufactures, more particularly antique manufactures, since it concerns a composition to be applied in order to preserve and restore textiles and paper, preferably ancient textiles and paper
Characterization of Madder compounds present in lake and textile, throw ammonia extraction and micro-sampling with Ag-gel matrix associated with SERS analysis
No full textNatural dyes from Rubia tinctorum L., used in tapestries
No full textPlants and insects had been used for a long time in the ancient period as source for dyes for art materials. On many tapestries, there is a widespread state of decay in charge of the colour of many yarns. This phenomenon may be due to presence of alteration products or total destruction of dye molecules. If we consider madder root, for example, contains a large number of compounds characterized by anthraquinone structures, thought as the main chromophores [1]. However, it is worth to notice that the analyses of madder’s extract, obtained in the same condition of dyeing bath [2], reveal also the presence of other types of molecules (not necessarily anthraquinones), present in the matrix. Some of them can be fixed on the yarn and, probably, these are involved in the degradation processes. During this work, it has carried out extraction of dyes from R.tinctorum L. and analysed by HPTLC (Fig. 1), 1H-NMR (Fig. 2). and ESI-MS With ESI-MS/MS, in both positive and negative mode, it has been possible to draw a structural profile of the compounds. These compounds are compared to those extracted by yarns [3] [4], dyed following the ancient recipes [2], in order to evaluate which molecules are fixed on the textile
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