A new approach to the mild extraction of madder dyes from lake and textile

In 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.