GC-FID Analysis to Evaluate the Possible Adulteration of Extra Virgin Olive Oil with Different Vegetable Oils

Extra virgin olive oil (EVOO) is a refined, highly valued, and relatively expensive food ingredient, typical of the Mediterranean area. Detection of EVOO that has been adulterated or counterfeited with the addition of variable quantities of low-quality and less-expensive vegetable oils is a challenging issue for analytical chemists. Analysis of fatty acid profiles in EVOO by gas chromatography with a flame ionization detector (GC-FID) may be conclusive or contribute to disclosing adulteration. Herein, a procedure of a GC-FID-based laboratory exercise for undergraduate analytical chemistry students is presented with results. The fatty acid profile of EVOO and blends obtained with five different vegetable oils (corn, peanut, sunflower, soybeans, and palm), individually added to EVOO up to 50% by weight, was determined using GC-FID. Hence, based on the data collected for pure oils, students were guided through the detection of counterfeiting and/or adulteration for an unknown EVOO sample. A survey of responses from a questionnaire showed that more than 85% of the students involved assigned a high score to this laboratory exercise.