Compound-specific δ¹³C and δ²H analysis of olive oil fatty acids

Fatty acids are the most abundant biomolecules in olive oil. In this study, we describe the analytical method developed to measure the δ¹³C, and for the first time, the δ²H values of fatty acid methyl esters (FAMEs) extracted from olive oil triglycerides, after base-catalysed transesterification with methanol. The extracted FAMEs are analysed using Gas Chromatography Combustion/Pyrolysis Isotope Ratio Mass Spectrometry (GC-C/Py-IRMS). The method made it possible to obtain baseline separation between the peaks of the main FAMEs (C16, C18, C18:1, C18:2). The accuracy, precision and uncertainty of the whole method (from preparation to measurement) were determined. Furthermore, the impact of methylation on δ¹³C and δ²H values was investigated. The obtained performance of the method is satisfying and allow the determination of reliable data. As δ¹³C and δ²H determined in bulk olive oils already demonstrated to be able on a some extent in distinguishing products according to their geographical origins, what it is expected applying this new method, is the improvement of the capacity of provenance differentiation.