Compound-specific δC and δH 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 δC, and for the first time, the δH 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 δC and δH values was investigated. The obtained performance of the method is satisfying and allow the determination of reliable data. As δC and δH 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.