Qualitative analysis of indigo precursors from woad by HPLC and HPLC-MS

Abstract

A qualitative method has been devised to analyse the indigo precursors in leaf extracts of woad (Isatis spp.) using HPLC coupled to an evaporative light scattering detector and confirmed using HPLC coupled, on line, to a particle beam mass spectrometer. Using this technique, indican has been positively identified in shoot extracts of European (I. tinctoria) and Chinese (I. indigotica) woad. Greater amounts of indican were found in the Chinese compared with the European woad. Copyright © 2000 John Wiley & Sons, Ltd.