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dc.contributor.authorYao, Wei Weien
dc.identifier.citationYao, W. W. (2011). Voltammetric studies on vitamin E in organic solvents and within lipid bilayer membranes. Doctoral thesis, Nanyang Technological University, Singapore.en
dc.description.abstractA series of model tocopherol compounds with differing degrees of methyl substitution around the aromatic ring were studied by variable scan rate (0.1- 500 V s-1) cyclic voltammetry experiments in CH3CN and CH2Cl2. On short voltammetric timescales α-TOH is oxidised in a chemically reversible –2e–/–H+ process to form a phenoxonium cation (α-TO+). The equilibrium and rate constants associated with the chemical steps were estimated by digital simulations of the variable scan rate data over a range of temperatures (T = 253-313K). α-Tocopherol films were deposited on the surface of gold, glassy carbon and platinum electrodes and their voltammetric behavior examined in aqueous solutions between pH 3 and 13. The voltammetric mechanism involved α-tocopherol being oxidised in a –2e–/–H+ process to form a phenoxonium cation (similar to the experiments in non-aqueous solvents), which underwent rapid reaction with water (or –OH¯ at pH > 7) and rearrangement to form α-tocopherol quinone in a chemically irreversible process. Electrochemical experiments were also performed by incorporating α-tocopherol into lecithin multilayers deposited onto the electrode surfaces. The results were very similar to those obtained for pure α-tocopherol films. α-tocopherol was oxidised to α-tocopherol quinone within the lecithin multilayers. However, the reduction process of α-tocopherol quinone appeared to be less chemically reversible as the pH was increased above pH 7. Two methods were used to incorporate α-tocopherol within the lecithin multilayers and both methods yielded similar electrochemical results.en
dc.format.extent185 p.en
dc.subjectDRNTU::Science::Chemistry::Physical chemistry::Electrochemistryen
dc.titleVoltammetric studies on vitamin E in organic solvents and within lipid bilayer membranesen
dc.contributor.supervisorRichard David Websteren
dc.contributor.schoolSchool of Physical and Mathematical Sciencesen
dc.description.degreeDOCTOR OF PHILOSOPHY (SPMS)en
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