Determination of Sterols and their Esters in Fats by Way of Transesterification in Different Solvents

ABSTRACT

The interference of triglycerides in the analysis of sterols and their esters in fats can be eliminated by transesterification of the sample dissolved in n-hexane with a solution of sodium hydroxide 2 mol/L. Since the analytes are distributed equally in n-hexane and in methanol, better results can be obtained by accurate measurements of the volumes, and processing the standards as the samples. Triglycerides and steryl esters are transesterified quantitatively by a solution of sodium hydroxide 2 mol/L using diethyl ether as solvent. At 40°C, ten minutes are sufficient to complete the reaction. The sterols are determined in fats using a mass spectrometer detector, at concentrations as low as 5 mg/Kg. Using FID, it was possible to analyze sterols present in concentrations higher than 100 mg/Kg.

Keywords::

• fat
• gas chromatography
• sterols
• steryl esters
• transesterification
• unsaponificable