Interference of peroxides with the determination of total carbonyls in autoxidized fats

Abstract

Abstract The contribution of hydroperoxides to the carbonyl content of autoxidized fats measured by a colorimetric 2,4‐dinitrophenylhydrazone procedure has been studied. Carbonyls were determined in radiation oxidized methyl myristate, in autoxidized methyl esters of oleie, linoleic and linolenic acids and in autoxidized oils, before and after reduction of hydroperoxides to hydroxyl groups. The results indicate that hydroperoxides decompose to carbonyl compounds during the carbonyl determination and give carbonyl contents that are too high. The extent of the interference depends on the nature of the peroxides and, therefore, on the fatty acid composition of the material and on other factors probably associated with the conditions during autoxidation and subsequent storage. For these reasons it is not possible to apply a erratum for peroxide interference based on the determined peroxide value. Carbonyl determinations on autoxidized lipids should be preceded by reduction of the peroxides to non‐carbonyl compounds, and care should be taken to prevent losses of low molecular weight carbonyls during this procedure.