Determination of Vitamin A and Vitamin E Contents in Fortified Cooking Oil using Visible Spectrophotometry

Abstract

For measuring vitamins A and E in fortified palm oil, trichloroacetic acid (TCA) through visible spectrophotometry and total antioxidant capacity (TAC) through phenanthroline method were developed. Using TCA determination method, vitamin A was directly measured at λ = 620 nm, with 92.84 % ± 0.74 accuracy, 0.79 % RSD, 2.15 IU/g limit of detection (LOD) and 7.17 IU/g limit of quantitation (LOQ). Using the mole difference calculation method of Fe2+ after Fe3+ reduction by total antioxidants and vitamin A, vitamin E content was indirectly measured. Total antioxidant capacity required for reducing Fe3+ was determined using phenanthroline method at λ = 510 nm. The temperature and reaction time for the saponification process were also evaluated. Optimum saponification was obtained at 70 ºC in 20 min with a recovery percentage of 93.81 %. Determined Vitamin E had 93.94 % ± 0.63 accuracy, 0.68 % RSD, 0.11 IU/g LOD and 0.76 IU/g LOQ.