High-performance liquid chromatography (HPLC)

Separation of sample was performed by HPLC analysis, using a Thermo Scientific System equipped with a Star Solvent Delivery System 230, Injector Rheodyne 7125, Pro Star 330 (UV – Photo Diode Array Detector). Chromatographic separation was performed on a Zorbax ODS column (250 x 4.6 mm i.d. 5 μm) (Agilent, USA). The flow rate was set to 0.9 mL/min. Operating conditions were as follows: column temperature, 20 °C, injection volume, 20 μL, UV-PDA detection at 278 nm. Before injection, extracts were filtered through 0.45 μL Nylon Membrane filter (Supelco, USA). Detection was performed with UV PDA detector by scanning from 278 to 360 nm.