RO samples enriched with synthetic antioxidants (ROBHT): Two samples of RO were enriched with the synthetic antioxidant BHT. The two new samples were named ROBHT(1) and ROBHT(2). ROBHT(1), ROBHT(2) were obtained as follows: BHT, which had previously been weighed and dissolved in 3 mL of ethanol, was added to 400 g of oil at a final concentration of 100 mg/kg and 200 mg/kg, as allowed by European and U.S. Regulations, respectively, and the sample was subsequently stirred for 5 min.