Stable isotope composition of light bio-elements in plant tissues reflects geo-climatic conditions of the production area, certain local agricultural practices and water uptake [1]. Therefore, the isotope composition of plant-derived fatty acids i.e. of extra virgin olive oil (EVOO), retains this information and its study allows assess both, the origin as well as certain aspects of its production means [2]. Actually, only one study has focused in hydrogen/deuterium (δ2H) isotope ratio composition of specific fatty acids in EVOO samples [3]. Analytical pyrolysis (Py-GC) when combined with isotope ratio mass spectrometry (IRMS) (Py-CSIA) allows the simultaneous analysis of different specific compounds in the same analysis minimizing sample manipulation [4]. Here, PyCSIA is used as tool for tracing the correlation between geographic variables and the hydrogen compound-specific isotope composition of EVOOs produced in the Mediterranean Basin. A total of 6 EVOO samples from 5 different Mediterranean countries (Portugal, France, Tunisia, Turkey and Spain) were sampled. Each sample was geo-referenced, obtaining data of altitude (m.s.a.l), oceanic distance (km), longitude (UTM), latitude (UTM), mean annual precipitation (mm) and mean annual temperature (o C). The hydrogen compound-specific isotopic composition (δ2H) of EVOOs was obtained by analytical pyrolysis (Py-CSIA) at 400 ºC (1 min). The δ2H value of the 11 major pyrolysis compounds present in all EVOO samples ranged between -120 and -270 mUr. Three representative major pyrolysis peaks of EVOO: palmitic acid, oleic acid and squalene, were selected as possible markers surrogated to the oil geographic origin. After a principal component analysis (PCA), it was found that δ2H was highly correlated with the geographic longitude of the production area. A partial least square (PLS) regression analysis indicated that using the δ2H value of the 3 major pyrolysis compounds it was possible to predict (P<0.05) altitude, oceanic distance and geographical longitude of EVOO production site. Although a wider study is necessary (in course) to include more locations and conditions, the results described here suggest that this methodology is of high potential to assess geographic origin and even growing conditions of EVOOs and to detect fraud activities.

The authors thanks to MedOOmics (Arimnet2/0001/2015) and INTERCARBON (CGL2016-78937-R) projects. We thank Dra. MV. Ruíz-Méndez (IG-CSIC) for providing Spanish EVOO sample. NTJM was funded by scholarship PosDoc/Por3O/OUT17. V Palma, D Monís and A Carmona are acknowledged for technical assistance.

[1] W. Meier-Augestein, Anal. Chim. Acta 465 (2002) 63-79. [2] JE. Spangeberg, N. Ogrinc, J. Agr. Food Chem. 49 (2001) 1534-1540. [3] M. Paolini, L. Bontempo, F. Camin, Talanta 174 (2017) 38-43. [4] JA. González-Pérez, NT. Jiménez-Morillo, et al., J. Chrom. A 1388 (2015) 236-243.

Póster (P-OA-08 ) presentado en la XVIII Reunión de la Sociedad Española de Cromatografía y Técnicas Afines (SECyTA 2018), Granada, del 2 al 4 de Octubre de 2018.

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