Quantification of Hydroxycinnamic Acids

The hydroxycinnamic acids were identified and quantified using an Agilent Technologies UHPLC system with a diode array detector (UHPLC-DAD). The separation was carried out using a Zorbax Eclipse Plus C₁₈ rapid resolution column (50 mm × 2.1 mm i.d. 1.8 μm particle size). A binary phase solvent system was used: solvent A was 0.1% acetic acid dissolved in water, and solvent B was 0.1% acetic acid dissolved in methanol. The solvent gradient was as follows: 0–11 min, 9 to 14% B and 11–15 min, 15% B. The column temperature was set at 30°C, the flow rate was 0.7 mL/min, and the detector was set at 280 nm. The results were expressed as μg/g of dry weight (DW) as determined using methanolic solutions (1.5–50 μg/mL) of caffeic acid, p-coumaric acid, ferulic acid, and sinapic acid as standards [11 (link)].