Stable isotope characterization of olive oils. I—Compositional and carbon‐13 profiles of fatty acids

Nearly 200 olive oils produced in the Mediterranean basin, mainly in Greece, during 4 yr from 1993 to 1996, were studied by gas chromatography (GC) and on‐line GC‐isotope ratio mass spectrometry (GC‐C‐IRMS). The composition of the oils in the more abundant fatty acids (C16:0, C16:1, C18:0, C18:1, C18:2, and C18:3) was obtained by GC after transesterification of the triglycerides into methyl esters. Using the hyphenated GC‐C‐IRMS technique, the 13C contents of the three most abundant acids, C16:0, C18:1, and C18:2, were measured with satisfactory accuracy. The results, analyzed in terms of geographical, temporal, and botanical factors, provide new criteria for the authentication of olive oils.