Extra virgin olive oil has long been a favorite object of fraudsters. In fact, this oil, which represents an essential part of the healthy Mediterranean diet, is the edible oil with the highest nutritional and sensory quality and consequently the most expensive among them. Within this context, continuous efforts have been devoted to the development of new and improved analytical methods able to detect emerging and sophisticated frauds.
The ∆ECN42 determination is one of the methods available for detection of small amount of seed oil mixed with olive oil. However, from an analytical point of view, the use of refractive index detector for triglycerides analysis, which is recommended by European legislation and the IOC, prevents gradient elution separations, thus leading to incomplete TAGs resolution and overlapping peaks.
Over the past few years, charged aerosol detection has become a widely used technology in laboratories. The charged aerosol detector (CAD) generates a signal in direct proportion to the quantity of analyte present. Furthermore, it can be used with gradient elution, thus representing a potential alternative to refractive index detector.
In the present study, ultrahigh pressure liquid chromatography coupled with CAD detection was applied to the analysis of extra-virgin olive oil triglycerides. Different chromatographic separations under gradient elution were proposed and optimized using C30 and C18 reversed-phase columns. The performance of CAD detector for trilinolein analysis was deeply investigated (linearity, LOD, LOQ, repeatability).
Finally, the proposed UHPLC-CAD methodology has been also applied to the determination of trilinolein and ∆ECN42 in extra virgin olive oil mixed in different proportions to simulate the adulteration of olive oil with high oleic sunflower oil, palm olein and a mix of them at different percentages of 2, 4, 6, 8 and 10 %.