Determination of some liposoluble antioxidants by coulometry and voltammetry

It is found that the interaction of retinol, ergocalciferol, and cholecalciferol with electrochemically generated bromine proceeds rapidly and quantitatively. The stoichiometric coefficients of the reaction are 1:2, 1:7, and 1:3, respectively. A coulometric determination of microgram amounts of individual liposoluble antioxidants in model solutions was performed with RSD = 1-5%. The voltammetric response of retinol and α-tocopherol was studied at a stationary platinum microelectrode in 0.1 M HClO 4 and 0.1 M CH 3COONa in acetonitrile. The quantification limit for α-tocopherol is 2.7 × 10 -4 M in 0.1 M HClO 4, and the quantification limits for retinol are 4.1 × 10 -5 M in 0.1 M HClO 4 and 2.1 × 10 -5 M in 0.1 M CH 3COONa. A procedure for the coulometric determination of total free liposoluble antioxidants in human blood serum is proposed