Oxygen Uptake during the γ-Irradiation of Fatty Acids

Summary

The radiation-induced oxidation of saturated and unsaturated fatty acids in aqueous solutions has been estimated by measurement of the continuous uptake of oxygen using an oxygen electrode. Chain reactions, initiated by HO^· radicals, are easily identified to be occurring in the case of unsaturated fatty acids. Other mild oxidation agents, namely (SCN), Br and N, are also found to be capable of oxidizing the polyunsaturated fatty acids. Evidence is presented that O may also initiate peroxidation. The oxidation of the polyunsaturated fatty acids is dependent on dose rate, fatty acid concentration, temperature and the presence of antioxidant and other protective agents. Kinetic studies of the reaction of (SCN) and Br with linoleic and linolenic acids have been carried out using pulse radiolysis. The bimolecular rate constants for both radical species with the lipids are approx 10⁷ mol⁻¹ dm³s⁻¹, below their critical micelle concentrations, and decrease at higher concentrations due to micelle formation.