Combined use of supercritical fluid extraction, micellar electrokinetic chromatography, and reverse phase high performance liquid chromatography for the analysis of antioxidants from rosemary (Rosmarinus officinalis L.)

Antioxidants from rosemary were determined by the combined use of supercritical fluid extraction (SFE) prior to reverse-phase high-performance liquid chromatography (RP-HPLC) or micellar electrokinetic chromatography (MEKC). The separation of antioxidants found in the SFE fractions was achieved by using a new MEKC method and a published HPLC procedure, both with diode array detection. The characterization of the different antioxidants was further done by HPLC-mass spectrometry. Advantages and drawbacks of HPLC and MEKC for analyzing the antioxidants found in the different extracts are discussed. From the results it is concluded that HPLC renders higher peak area and is better in its reproducibility than MEKC; both techniques provide similar analysis time reproducibility. The main advantage of MEKC is its much higher separation speed, which is demonstrated to be useful for the quick adjustment of SFE conditions, allowing rosemary fractions of higher antioxidative power to be obtained quickly. Moreover, the possibilities of this approach for following the degradation of antioxidants are discussed.