Separation and quantification of vitamin E isoforms through ion chromatography in groundnut oil

Abstract

A convenient analytic method was developed for measuring major vitamins E isomeric forms (α-, β-, γ- and δ-Tocopherol) in groundnut oil. A 5 µm Polar Advantage II, 120 Å, C-18 column, with the dimensions of 4.6 × 150 mm and maintained at 25 °C, is used to resolve vitamin E. The separation starts with a 5.5 min composition hold with absolute methanol as mobile phase with flow rate of 1.0 ml/min, followed by reduction in flow rate i.e. 0.4 ml/min for up to 9.0 min and 0.6 ml/min for last one minute. Detection is accomplished using UV detector at wavelength 295 nm. The elution order of tocopherols in TG-51 genotype was δ-tocopherol, (β+γ)- tocopherol and α-tocopherol with retention time of 4.87, 6.01 and 6.43 minutes respectively. The total tocopherol content in TG-51 was found to be 567 ppm with 49 ppm of δ-tocopherol, 109 ppm of β+γ-tocopherol and 409 ppm of α-tocopherol. Peaks of α-, β-, γ- and δ-Tocopherol in groundnut oil were identified by comparing their retention times with commercially available standards (Sigma–Aldrich, St. Louis, MO, USA).