Pyrolysis-compound-specific hydrogen isotope analysis (δ2H Py-CSIA) of Mediterranean olive oils

The analysis of the hydrogen stable isotope composition (delta H-2) of organic compounds provides information about its geographical origin. In this work, delta H-2 composition of specific compounds released by direct analytical pyrolysis (Py-CSIA) of extra virgin olive oils EVOOs was studied avoiding the use of any chemical and/or physical treatments, derivatization or previous separation steps. A collection of EVOOs from Mediterranean countries (Portugal, Spain, France, Tunisia and Turkey) was used for authentication of the olive oil samples. The delta H-2 value for 9 pyrolysis compounds present in all EVOOs, ranged between -112 and - 267 mUr. These compounds were selected as possible surrogate descriptors linked to the olive oil geographic origin. Principal Component Analysis showed that delta H-2 was highly correlated with geographical longitude and annual temperature. Multiple Linear Regression analysis revealed that delta H-2 value of pyrolysis compounds can significantly (P < 0.05) predicts longitude, mean annual temperature and distance to the sea. The results suggest that the methodology used has a high potential to assess EVOOs geographic origin. This is the first report that evaluates delta H-2 directly from the pyrolysis products of olive oil using Py-CSIA. The approach used represents an innovative, fast, reproducible and reliable authentication technique.