Application of voltammetric technique to the analysis of indanthrene dye in alkaline solution

The Indanthrene Olive Green B (C.I. Vat Green 3; C.I. 69500), VG3 dye, a vat dye bearing an anthraquinonoid group and a ketonic group, can be detected by differential pulse voltammetry in alkaline solution using glassy carbon electrode. On the adsorbed form the dyes are reduced into three cathodic steps at −0.54 V, −0.65 V and −0.93 V vs Ag/AgCl. The leuco form generated after previous electrolysis at controlled potential of −1 V can be detected by voltammetry due to its reoxidation peak at −0.08 V. An analytical method is proposed for determining the vat dye using modified glassy carbon electrode by electrochemical activation in alkaline medium. Linear relationship was observed between IpaIpa vs concentration from 1 × 10−5 mol L−1 to 6.0 × 10−4 mol L−1. The detection limit was calculated to be 9.3 × 10−6 mol L−1.