HPLC Analysis of Phenolic Compounds

HPLC analyses were performed on an Agilent Technologies (Waldbronn, Germany) modular model 1260 Infinity II system consisting of a vacuum degasser, a quaternary pump, an autosampler, and a UV/Vis detector. The chromatograms were recorded using an Agilent OpenLab CDS ChemStation Edition (Rev. C.01.10). The analysis of phenolic acids and flavonols was carried out on an Ascentis Express C₁₈ column (150 × 3.0 mm I.D., 2.7 µm, Supelco, Bellefonte, PA, USA). The mobile phase was composed of 0.1% HCOOH (v/v) in both (A) water and (B) ACN. The gradient elution was modified as follows: 0–5 min 3% B, 5–45 min from 3% to 50% B. The post-running time was 10 min. The flow rate was 0.4 mL/min. The sample injection volume was 20 µL. UV chromatograms were acquired at 254 nm. Three injections were performed for each sample [5 (link),8 (link)].