Estimation of the antioxidative properties of tocopherols – an electrochemical approach

The electrochemical behaviour of tocopherols on solid platinum electrodes, using cyclic voltammetry, linear sweep voltammetry and differential pulse voltammetry, in non-aqueous media, was studied. D-α-, D-γ-, and D-δ-tocopherol (E vitamins) provided well-defined voltammograms, each of them exhibiting a characteristic peak (respectively 0.550 V, 0.700 V and 0.750 V vs. a silver, silver chloride/chloride reference electrode). The differential pulse voltammograms were suitable for the electroanaytical determination, in the respective concentration ranges of (2 ×10⁻⁸÷1×10⁻⁵) mol l⁻¹, (2.2×10⁻⁸÷1.4×10⁻⁶) mol l⁻¹ and (2.2×10⁻⁸÷3.31×10⁻⁵) mol l⁻¹, of α-, γ-, δ- tocopherol. An electrochemical estimation of the tocopherols' antioxidative properties, related to the free radical 2,2′diphenyl-1-pycrilhydrazil was made. The maximum value of the characteristic peak of tocopherol decreased with DPPH concentration. Received: 26 July 1999 / Revised version: 1 October 1999