Identification of red natural dyes in post-byzantine icons by HPLC
A high performance liquid chromatography (HPLC) methodology, combined with UV-Vis Diode Array Detection, is developed for the separation and identification of five reddish natural dyestuffs: cochineal, madder, lac dye, dragon blood, and brazilwood. The method is used for the identification of organic dyes in extracts originating from five icons, four of which are representative for the post Byzantine era (15th to 19th century) and one is typical for the Byzantine coloring technology (created at the 14th century). The origin and the nature of the coloring content of Mediterranean art objects, created in these historical periods are not well known. Carminic acid, the main active, coloring, ingredient of cochineal was identified in four icons, including the one of the 14th century. Brazilwood was found to be the only organic colorant in one icon of the post Byzantine era. It was also present, in addition to cochineal, in the icon of the Byzantine period. Further discussion, associated with the dyestuff, origin, is provided based on the analytical results and the available historical data.