Electrochemical characterization and detection of vitamin E in real samples

Abstract

Vitamin E is an important antioxidant and plays an essential role in cellular respiration. At room temperature, it exists in the form of viscous oil and is highly soluble in fat. Vitamin E is a group of eight compounds: four tocopherols and four tocotrienols. In this study, α-tocopherol (α -TOH) was characterized using cyclic and differential pulse voltammetry and was detected with high-performance liquid chromatography in real samples (kale, parsley, and a powdered dietary supplement). Cyclic and differential pulse voltammograms have shown one oxidation peak which corresponds to the oxidation of α -TOH. In the oxidation of α -TOH, rapid two-electron oxidation coupled with one proton loss \((-2e^{-}/-1H^{+})\) occurred, and a diamagnetic cation \((\alpha -TO^{+}) \) was formed. Oxidation of α -TOH α is an irreversible and a diffusion-controlled process since the linear correlation between anodic peak current, Ip,a, and the square root of scan rate \((v)^{1/2}\) was observed. It was also determined that the anodic peak current of α -TOH increases with the increase of its concentration (linear response was obtained in the concentration range from 0.43 \(mg/dm^{3} \) to 70.41 \(mg/dm^{3} \)). The obtained values of α -TOH in real samples were 8.267 mg/kg for parsley, 1.492 mg/kg for kale, and 0.067 mg/kg for powdered dietary supplement.

Keywords

• α –tocopherol
• cyclic voltammetry
• differential pulse voltammetry
• high-performance liquid chromatography
• vitamin E