Identification of Onion Dye Chromophores in the Dye Bath and Dyed Wool by HPLC-DAD: An Educational Approach

Abstract

Onion skins (Allium cepa L.) and hydrated potassium aluminum sulfate were used to dye wool samples. The main chromophores associated with this natural dye source, quercetin and quercetin-4′-O-glucoside, were identified in the dye bath and in wool extracts by high-pressure liquid chromatography (HPLC)equipped with a diode array detector (DAD) with the help of standards. Two procedures were used to extract dye molecules from dyed wool prior to HPLC-DAD qualitative analysis and the analytical methodology used was discussed in terms of the analysis of historical textile pieces dyed with natural sources.