High-Performance Liquid Chromatographic Determination of 2-Alkenals in Oxidized Lipid as Their 7-Amino-6-methylquinoline Derivatives

High-performance liquid chromatographic determination of several 2-alkenals, specially acrolein, crotonaldehyde, 2-pentenal, 2-hexenal, 2-heptenal, 2-octenal and 2-nonenal, were studied using the precolumn derivatization reagent 2, 4-diaminotoluene. After the selective condensation of these 2-alkenals to form fluorescent 7-amino-6-methylquinoline derivatives, separation of these compounds was achieved on a ODS column (150×4 mm i.d.) with a linear gradient system of acetonitrile and 50 mM mono-ammonium phosphate containing 5 mM sodium 1-octanesulfonate (from 20% acetonitrile to 60% acetonitrile in 1 h), and the separated quinoline derivatives were detected with a fluorescence monitor (396 nm for excitation and 485 nm for emission). There autooxidized unsaturated fatty acid methyl esters and five autooxidized edible oils were subsequently assayed for acrolein (C3), crotonaldehyde (C4), 2-pentenal (C5), 2-heptenal (C7), 2-octenal (C8) and 2-nonenal (C9). The peak of 2-hexenal was interfered with the unknown peak derived from oxidized lipids. Their detection limits (S/N=2) were 10, 10, 25, 25, 50, 50 pg for acrolein, crotonaldehyde, 2-pentenal, 2-heptenal, 2-octenal and 2-nonenal, respectively.