Study of Electrochemical Behaviour of Carotenoids in Aqueous Media

Abstract

Abstract Focus of this research was electrochemical study of β‐carotene, astaxanthin and lutein in aqueous media. Compounds were investigated on paraffin impregnated graphite electrode (PIGE) in 0.1 M HClO 4 aqueous electrolyte using square‐wave voltammetry (SWV) with pulse amplitude of 50 mV and step potential of 2 mV. Voltammetry of immobilized microparticles (VIM) allowed determination of β‐carotene and astaxanthin as solids immersed in aqueous electrolyte. Results obtained with SWV revealed oxidation peaks at 0.88 V and 1.09 V versus Ag/AgCl for β‐carotene and astaxanthin, respectively. To obtain additional information about their behaviour, stripping voltammetry microprobe (SPV) was employed. With this technique the responses of astaxanthin, β‐carotene and lutein exhibit three peaks (−0.345 V, 0.47 V and 0.65 V), two peaks (0.477 V and 0.725 V) and a single peak at 0.687 V, respectively. Based on these results, antioxidant activity of these carotenoids is in order: astaxanthin > β‐carotene > lutein. Good dose‐response relationship between carotenoid concentrations precipitated on PIGE and net peak current was obtained, but in rather narrow concentration range for each compound.