AIC's 41st Annual Meeting

Knowledge of the chemical composition of the dyestuffs used on textiles can provide information on the history and origin of the textile as well as the technology employed to create it. This information may be valuable for conservation or curatorial purposes. While dyestuffs used on textiles can be of natural or of synthetic origin, the coloring matter involved in each case is generally one or more organic molecules. Confident identification of the dyestuffs on textiles often requires extraction of all of the colorants from the fiber samples, the resolution of the mixture into single chemical entities, and the subsequent individual identification based on chromatographic retention, light absorption characteristics, and molecular mass. In dye analysis, the separation of the colorants by liquid chromatography (LC) is combined with diode array detection (DAD) and mass spectrometry (MS) for structural characterization. Since the Conservation Science Lab at the Indianapolis Museum of Art began its operation in 2010, we have begun to employ LC-DAD-MS for dye analysis. In this presentation, we will share with you some details about the format of our experimental set up, some of the challenges we have encountered in sample extraction, the characterization of dye molecules, with and without relying on reference standards, and the issue of dye identity assignment. The data presented will include the characterization of certain reference dyestuff samples, such as madder, dyer’s greenweed and Scotch broom, as well as the extracts of fibers from an Uzbek coat, in which we have identified such synthetic colorants as Fast Red AV and Acid Green 16, along with natural alkaloids berberine and palmatine that have been reported to be present in Berberis, Coptis or other plant species.