Identification of Natural Dyestuff in Archeological Coptic Textiles by HPLC with Fluorescence Detection

High performance liquid chromatography with UV–Vis detection and post-column derivatization with fluorimetric detection was used for analysis of dyes used in Coptic textiles. To obtain the best separation of analyzed compounds composition of mobile phase was optimized. The best results were obtained for 25 mM phosphoric buffer at pH 2.5 with gradient change of methanol concentration (Table 1). As post-column reagents used to enhance fluorescence signal of analyzed compounds, solutions of Al(III), Ga(III), In(III), and Zn(II) were used. The highest increase of fluorescence signal was observed for Ga(III) and 10 mM solution of this ion was used for investigation of plant extracts and extracts from Coptic textiles.