Determination of Phthalates into Vegetable Oils by Isotopic Dilution Gas Chromatography Mass Spectrometry

The presented method for the determination of a number of phthalic acid esters into oily media is based on their extraction by acetonitrile with precipitation under freezing and subsequent solid-phase extraction using alumina. This technique was checked as the best procedure to separate lipophilic phthalates from fatty media achieving elimination of contamination by excess use of solvents. Extracted phthalates are determined in acetonitrile solutions with gas chromatography in conjunction to isotopic dilution mass spectrometry using D4 isotopic labeled derivatives. Full validation of the method was carried out and background effect was examined. Method calibration for extraction from oil resulted in limit of detection (LOD) of 7-10 ng g(-1) and limit of quantification (LOQ) of 20-50 ng g(-1) for DMP, DEP, DiBP, DBP, DEHP, and BBP and in LOD 500 ng g(-1) and LOQ of 1,500 ng g(-1) for DiNP and DiDP. Real samples of virgin olive oil from olive press establishments from three different areas were analyzed and the phthalates content was below detection limit for all phthalic esters under consideration for nonindustrial areas and in measurable concentrations for industrial areas specifically with regard to DiBP.