Methods for determining peroxide in lipids

Abstract

Abstract The relative efficiencies of three methods for the determination of peroxide oxygen in fatty materials have been compared using methyl oleate, linoleate and linolenate oxidized under standard conditions to known oxygen‐absorptions. The iodometric method indicated the conversion of 71–91% of the oxygen absorbed to peroxy‐compounds, but the ferric thiocyanate and 2: 6‐dichlorophenolindophenol methods both gave abnormally high results in the presence of atmospheric oxygen, and values which were obviously too low in its absence. Nevertheless, the aerobic ferric thiocyanate method shows excellent reproducibility, requires much less material than the iodometric method, and under any one set of conditions gives results which appear to be directly proportional to the iodometric values. The 2: 6‐dichlorophenolindophenol method behaved similarly in most respects to the ferric thiocyanate method, but reproducibility appeared to be poorer and interference by atmospheric oxygen and by traces of copper when present was more marked.