A rapid and efficient method for dialkyl ketones and sterols determination in fat

The present work deals with the optimization of a fast method for the determination of dialkyl ketones (DAKs) in interesterified fats. Microwave-assisted saponification was optimized, followed by purification on a lab-packed silica solid-phase extraction (SPE) cartridge. The method proposed may be used for the determination of DAKs or both DAKs and sterols by simply eluting an additional fraction from the SPE cartridge. The final determination was performed by gas chromatography- flame ionization detector (GC-FID) for quantification and gas chromatography-mass spectrometry (GC-MS) for confirmation purposes. The proposed method showed good recoveries (>80%) and limit of quantification (0.04-0.07 μg/g for the 4 standard DAKs and of 0.07 μg/g for α-cholestanol). Repeatabilities (n=3) were below 15% for DAKs and generally lower than 6% for sterols. Accuracy on the entire sterol profile was confirmed in comparison to the International Olive Council reference method. The method was finally applied to real-world samples before and after chemical interesterification.