*3.3. HPLC–DAD–MS Analysis*

HPLC–DAD–MS was performed using a system consisting of a CBM-20A system controller (Shimadzu USA Manufacturing Inc., Canby, OR, USA), two LC-20 CE pumps (Shimadzu USA Manufacturing Inc., Canby, OR, USA), a DGU-20A3 degasser (Shimadzu Corp., Kyoto, Japan), an SIL-20A autosampler (Shimadzu USA Manufacturing Inc., Canby, OR, USA), a diode-matrix SPD-M20A (Shimadzu USA Manufacturing Inc., Canby, OR, USA), and a mass-spectrometric detector LCMS-2020 (Shimadzu Corp., Kyoto, Japan). The separation was carried out on a Discovery HS C18 column (150 × 2.1 mm, 3 μm particle size, Supelco, Bellefonte, PA, USA) with a Supelguard Ascentis C18 pre-column (2 × 2.1 mm, 3 μm particle size, Supelco, Bellefonte, PA, USA) using a binary gradient of H2O (A)/MeCN (B) with the addition of 0.2% AcOH at a flow rate of 0.2 mL/min and column temperature of 40 ◦C. The gradient was as follows: 0–6 min, 10–40% (B); 6–11 min, 40–100% (B); 11–12 min, 100% (B), 12–13 min, 100–10% (B); 13–17 min, 10% (B). The chromatograms were recorded at 254 nm. Mass spectra were taken in the electrospray ionization (ESI) mode at atmospheric pressure, recording negative ions (1.50 kV) in the *m*/*z* range of 100–900 with the following settings: drying gas, N2 (10 L/min); nebulizer gas N2 flow, 1.5 L/min; temperature for the curved desolvation line (CDL), 200 ◦C; temperature of heat block, 250 ◦C; interface voltage, 3.5 kV. Before analysis, samples were filtered through a 0.2 μm polytetrafluoroethylene (PTFE) syringe filter. The injection volume was 5 μL.
