Electrochemical characterization and detection of vitamin E in real samples.

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 (α -TO⁺ ) was formed. Oxidation of α -TOH α is an irreversible and a diffusion-controlled process since the linear correlation between anodic peak current, I_p,a, and the square root of scan rate (ν) ^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/dm³ to 70.41 mg/dm³ ). 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. [ABSTRACT FROM AUTHOR]