4.4. HPLC-PDA/-ESI-MS Identification and Quantification of Phenolic Compounds

To confirm the identified compounds, an ESI-MS analysis was also conducted. The ESI-MS analysis was performed using an Agilent 1200 system equipped with a binary pump delivery system (LC-20 AT, Prominence), a degasser (DGU-20 A3, Prominence), a diode array SPD-M20 A UV–VIS detector (DAD), and an Eclipse XDB C18 column (4 μm, 4.6 × 150 mm) was used. The mobile phases used the following solvents: (A) bidistilled water and 0.1% acetic acid/acetonitrile (99/1 v/v), and (B) acetonitrile and acetic acid 0.1%. The gradient elution system conditions were as follows: 0–2 min, isocratic with 5% (v/v) eluent B; 2–18 min, linear gradient from 5% to 40% (v/v) eluent B; 18–20 min, linear gradient from 40% to 90% (v/v) eluent B; 20–24 min, isocratic on 90% (v/v) eluent B; 24–25 min, linear gradient from 90% to 5% (v/v) eluent B; 25–30 min, isocratic on 5% (v/v) eluent B. The flow rate was 0.5 mL/min, and the column temperature was maintained at 25° C. The chromatograms were monitored at 280 and 340 nm, respectively. The identification of compounds was conducted based on their retention times, UV-VIS spectra, standards (chlorogenic acid, caffeic acid, quercetin-rutinoside, quercetin-glucoside, ellagic acid, and myricetin, all purchased from Sigma-Aldrich, and published data. The mass spectrometric data were obtained using a single quadrupole 6110 mass spectrometer (Agilent Technologies, Chelmsford, MA, USA) equipped with an ESI probe with scanning range between 280 to 1000 m/z. The measurements were performed in the positive mode, with an ion spray voltage of 3000 V and a capillary temperature of 350 °C.