The determination of tocopherols in vegetable oils by square‐wave voltammetry

Abstract

Square‐wave voltammetry (SWV) has been applied to the determination of tocopherol concentrations in eight vegetable oils: canola, corn, olive, peanut, safflower, sesame, soybean, and sunflower. This technique has a lower limit of detection and somewhat better resolution than differential‐pulse voltammetry (DPV) and is significantly faster than both DPV and high‐performance liquid chromatography (HPLC), the technique most often used for tocopherol determinations. The tocopherols are oxidized at a stationary glassy carbon electrode as its potential is scanned from 0.40 to 1.00 Vvs Ag/AgCl at a rate of 20 mV/s. The currents that arise from these oxidations are directly proportional to the tocopherols’ concentrations. A standard addition method is used to determine the tocopherol contents of the oils listed. Under the conditions employed, the limit of detection is 10 mg/L tocopherol in oil.