| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1200859 | Journal of Chromatography A | 2013 | 9 Pages |
•Three steps SPE fractionation of FAMES on a 10% moisture silica column is proposed.•The step removes the interfering and co-eluting hydroxy fatty acids and allows analysis of epoxy fatty acids on a polar column without silylation and hydrogenation.•Well resolved peaks have been obtained.•The method has been implemented on refined fresh vegetable oils and has shown high sensitivity.•High levels of total epoxy fatty acids have been found in refined fresh oils.
In this study an improved method for analysis of epoxy fatty acids is reported. Data obtained from analysis of polar fatty acids has previously been presented, but due to the high number of compounds that co-elute in the polar fraction, the resultant chromatograms are complex which may lead to compromising the accuracy of the data. A three steps separation of fatty acid methyl esters (FAMEs) by solid-phase extraction (SPE) on a silica gel column to remove hydroxy fatty acid interferences was proposed. This approach is opposed to a two step separation procedure that has been often used to prevent analytical interferences caused by non-altered fatty acids. A gas chromatograph with a flame ionization detector (GC-FID) equipped with a polar CP-Sil 88™ column was used. Quantification was based on the use of methyl nonadecanoate (C19:0), as an internal standard. Individual mono epoxy fatty acids were well separated without co-eluting compounds. The optimized method was finally applied to screen epoxy fatty acids in 37 fresh oil samples. Results obtained for the total epoxy fatty acids were in the range 0.03–2 mg g−1 of oil with repeatability coefficient of variation (CV) ranging from 2.8 to 9.9% for duplicate analysis showing that the results obtained are repeatable.
