Simple and rapid method to analyse squalene in olive oils and extra virgin olive oils

Olive oil is one of the main vegetable sources of squalene, substance with several interesting properties and applications. This work aims to present and validate a rapid method to quantify squalene in olive oil by gas chromatography (GC) coupled with flame ionization detector and to apply the method to extra virgin olive oils (EVOOs) and olive oils (OOs) from large scale distribution retail, and to some EVOOs from little companies productions (Italian monovarietal Leccino and Frantoio EVOOs, and niche blend Italian EVOOs). A transmethylation of the oil sample is exploited to allow the direct GC analysis avoiding the separation from saponifiable fraction. The optimized conditions provide high sensitivity, short time (total GC run time is 5 min and about 10 min are needed for sample preparation) and require instruments and materials usually available in most of the laboratories. The method was validated by determining linearity, intraday and interday repeatability, recovery, limit of detection and limit of quantification. Within EVOOs investigated, the niche blend EVOO contained significantly higher amount (P < 0.05) of squalene (0.81–1.02 g/100 g) as compared to each of the other EVOOs groups investigated (monovarietal Leccino and Frantoio EVOOs and EVOOs from large scale distribution retail) containing a squalene concentration in the range 0.31–0.65 g/100 g; in OOs, the content, 0.17–0.27 g/100 g, was significantly lower (P < 0.05) as compared to EVOOs.