Determination of hydroperoxides in liposomes by the modified IDF and the modified tiron methods

Two new methods, the modified International Dairy Federation and the modifi ed Tiron methods, were developed for the determination of hydroperoxides in liposomes. Interferences of alpha-tocoferol and egg-phosphatidylcholine (E PC) required a solid-phase extraction before the analysis to eliminate alph a-tocoferol and a fluid-fluid extraction based on the solvent triangle of B ligh and Dyer to separate EPC. The developed color, using thiocyanate and T iron, respectively, as complex-formers for the generated ferri-ions, was me asured spectrophotometrically. Both techniques showed good reproducibility and high sensitivity. Peroxide contents of 0.04 and 0.07% (g/g) in EPC samp les were easily determined.