4.3. Extraction of Plant Material

One hundred milligrams of each dried and ground root were submitted to ultrasonic extraction with 10 mL of methanol/water (70:30, v/v), twice, for 10 min each. The resulting two extracts were combined and centrifuged at 4000 rpm for 10 min. The supernatant was brought to a volume of 30 mL and filtered through a 13 mm diameter, 0.22 μm pore diameter, and hydrophilic PTFE syringe filter, prior to HPLC-PDA-MS/MS analysis. The repeatability of extract composition was evaluated on 35 accessions with the RSD% between three extracts < 5%. The efficiency of the extraction process was determined by calculating the recovery of the three markers, which were 119%, 112% and 101% for cynarin, echinacoside and dodeca-2E,4E,8Z,10E/Z-tetraenoic isobutylamide, respectively.