Development, validation and application of an UFLC-DAD-ESI-MS method for determination of carbonyl compounds in soybean oil during continuous heating

A method was developed for the extraction and UFLC-DAD-ESI-MS analysis of carbonyl compounds (CCs) in oils heated to 180 degrees C. Different parameters were evaluated, and the best results were 1.5 ml of acetonitrile as the extraction solvent, manual stirring for 3 min and 30 min of sonication time. The method was validated using soybean oil samples spiked with CCs at concentration levels ranging from 0.2 to 10.0 mu s. mL(-1). The average recoveries in the lowest concentration level ranged from 70.7% to 85.0%. Detection limits ranged from 0.03 to 0.1 mu g.mL(-1), and the quantification limit was 0.2 mu g.mL(-1) for all compounds. When the method was applied to samples of heated oil, the CCs identified were 4-hydroxy-2-nonenal, 2,4-decadienal, 2,4-heptadienal, 4-hydroxy -2-hexenal, acrolein, 2-heptenal, 2-octenal, 4,5-epoxy-2-decadal, 2-decenal, and 2-undecenal, with the first three mentioned presenting the highest mean concentrations after heating, specifically 36.9, 34.8 and 22.6 mu g.g(-1) of oil, respectively. (C) 2016 Elsevier Ltd. All rights reserved.