Determination of phenolic acids in extra virgin olive oil using supercritical fluid chromatography coupled with single quadrupole mass spectrometry

Abstract

Phenolic acids represent one third of the total phenolic compounds in extra virgin olive oil (EVOO) and contribute greatly to the biological and sensory properties of EVOO. In the present research, an analytical method based on supercritical fluid chromatography coupled with single quadrupole mass spectrometry (SFC-MS) was developed for the analysis of phenolic acids in EVOOs. The chromatographic and MS conditions were optimized in terms of selectivity, peak shape and sensitivity. Satisfactory separation of 12 phenolic acids was achieved within 20 min on a Platisil CN column (250 mm × 4.6 mm, 5 μm) using 7% (v/v) water and 0.5% (v/v) formic acid in MeOH as mobile phase additives at the backpressure of 140 bar and temperature of 60 °C. The developed method was validated by evaluating the linearity, sensitivity, repeatability, intermediate precision and accuracy. The limits of detection (LODs) and limits of quantification (LOQs) of the SFC-MS method for phenolic acids ranged from 0.03 to 5.00 μg/mL and 0.08 to 15.0 μg/mL, respectively. The relative standard deviations (RSDs) for intraday and interday precision were lower than 9.91% and the recoveries ranged from 80.2 to 117% and 80.9 to 118% for low-level and high-level concentrations of standards spiked in olive oil, respectively. Compared to an HPLC method, the SFC method was about three times faster and provided better selectivity. Finally, the SFC-MS method was successfully employed for the quantitative analysis of phenolic acids in EVOOs. Differences in individual and total phenolic acid contents were observed between six varieties.

Keywords: Extra virgin olive oils; Phenolic acids; Supercritical fluid chromatography.