A simple and quick determination of aldehydes in autoxidized vegetable and fish oils

A simple and quick method for the quantitative determination of aldehydes in oxidized oils was established. The analysis was based on the reaction of N,N‐dimethyl‐p‐phenylenediamine (DPPD) with aldehydes in the presence of acetic acid. Reaction products were determined by visible absorption at wavelengths of 400, 460 and 500 nm. The errors of the DPPD method in the analyses of total aldehydes in authentic mixtures of various aldehydes were less than 5%, and this method could be used successfully to determine aldehyde contents in oxidized vegetable and fish oils. The reaction time of the DPPD method (10 min at 30°C) is much shorter than that of the conventional method that uses 2,4‐dinitrophenylhydrazine as a reagent (30 min at 60°C). The simplicity of the procedure enables a quick determination of aldehyde contents in oxidized oil samples.