Analysis of nonpolar lipophilic aldehydes/ketones in oxidized edible oils using HPLC-QqQ-MS for the evaluation of their parent fatty acids.

Six edible oils with different fatty acid compositions were used to explore nonpolar lipophilic aldehydes/ketones produced by possible parent fatty acids after accelerated oxidation. Simultaneous determination of 20 aldehydes and five ketones within the C2-C10 range was carried out using HPLC-QqQ-MS technique. Close relationships among the amounts of aldehyde carbonyls and the initial contents of oleic, linoleic and α-linolenic acids were revealed by principal component analysis. Pentanal, hexanal, hexanone, heptanal, 2-propenal, 2-heptenal, 2-octenal, 2-nonenal and 2,4-decadienal were the key carbonyls in close association with the initial content of linoleic acid. Ethanal, acetone, propanal, butanal, 2-pentenal, 2-hexenal, 2,4-heptadienal and 2,4-nonadienal were the key markers closely related with the initial content of α-linolenic acid. Furthermore, octanal, octanone, nonanal, nonanone, decanal, decanone and 2-decenal were the oxidation indexes linked to the initial content of oleic acid. The results provide a complete picture of secondary oxidation products in edible oils and possible source of parent fatty acids.