Determination of toxic α-dicarbonyl compounds in sesame oils using dispersive liquid-liquid microextraction coupled with gas chromatography-mass spectrometry.

Glyoxal, methylglyoxal, and diacetyl are toxic α-dicarbonyl compounds found in heat-processed foods, including edible oils. Dispersive liquid-liquid microextraction was combined with gas chromatography mass spectrometry to determine the glyoxal, methylglyoxal, and diacetyl contents in sesame oil. Chloroform and methanol were selected as the optimal extraction and dispersive solvents, respectively. The maximum derivatization efficiency was obtained using 500 µg of the derivatization agent, o-phenylenediamine. The derivatization of glyoxal was completed in 1 h, whereas those of methylglyoxal and diacetyl were completed immediately. The optimized method was validated, and was found to exhibit a good linearity, recovery, intraday repeatability, and interday reproducibility. The α-dicarbonyl compound concentrations in the oils were dependent on the roasting temperature. The sesame oil concentrates contained 0-175.4, 0-990.5, and 0-220.9 ng g-1 of glyoxal, methylglyoxal, and diacetyl, respectively. For the perilla oils, the respective concentrations were 0-96.4, 0-410.8, and 0-197.5 ng g-1.