A simple and rapid method for concurrent determination of petroselinic and oleic acids in oils

A procedure to determine the petroselinic acid/oleic acid ratio in oils is described. The method is based on transesterification of the constituent fatty acids to methyl esters. An aliquot of the solution of the esters is then analyzed by capillary gas chromatography; another aliquot is used for epoxidation of the double bonds with 3-chloroperoxybenzoic acid and subsequent opening of the oxirane ring with hydrochloric acid to obtain the chlorohydrin derivatives. The hydroxy groups are then silanized, and the reaction mixture is analyzed by high-resolution gas chromatography-mass spectrometry. The procedure is precise, rapid, and reproducible, and several samples can be analyzed in one working day.