Reactions of superoxide anion radical with antioxidants and their use in voltammetry

Kinetic parameters were calculated for the electrochemical reduction of oxygen at a glassy-carbon electrode with the generation of superoxide radical anions in a 0.05 M solution of (C2 H5 )4NI in dimethylformamide in the presence of fat-soluble antioxidants, retinol and α-tocopherol. A procedure based on the protonation of the radical anion with antioxidant molecules is proposed for the voltammetric determination of antioxidants to determine milligram amounts of retinol and α-tocopherol in model solutions (RSD = 1-2%). The calibration graphs for retinol and α-tocopherol are linear in the concentration ranges 9.7 × 10 -5-2.3 × 10-3 and 6.2 × 10-4-3.1 × 10-3 M, respectively. The detection limits for retinol and α-tocopherol are 4.8 × 10-5 and 4.1 × 10 -4 M, respectively. The procedure was applied to the determination of the active component (retinol and α-tocopherol) in pharmaceuticals. © 2005 Pleiades Publishing, Inc

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

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

Reactions of superoxide anion radical with antioxidants and their use in voltammetry

Kinetic parameters were calculated for the electrochemical reduction of oxygen at a glassy-carbon electrode with the generation of superoxide radical anions in a 0.05 M solution of (C2 H5 )4NI in dimethylformamide in the presence of fat-soluble antioxidants, retinol and α-tocopherol. A procedure based on the protonation of the radical anion with antioxidant molecules is proposed for the voltammetric determination of antioxidants to determine milligram amounts of retinol and α-tocopherol in model solutions (RSD = 1-2%). The calibration graphs for retinol and α-tocopherol are linear in the concentration ranges 9.7 × 10 -5-2.3 × 10-3 and 6.2 × 10-4-3.1 × 10-3 M, respectively. The detection limits for retinol and α-tocopherol are 4.8 × 10-5 and 4.1 × 10 -4 M, respectively. The procedure was applied to the determination of the active component (retinol and α-tocopherol) in pharmaceuticals. © 2005 Pleiades Publishing, Inc

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

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