Electrochemical processes of solid indirubin and its sulfonated form were comparatively studied in aqueous buffers by cyclic voltammetry and long-path-length thin-layer UV–vis spectroelectrochemistry, using a carbon paste working electrode with or without indirubin particles attached. The two forms of indirubin gave similar voltammetric features as well as main reaction products. Alkaline pH of electrolyte generally had a negative effect on both ...
