3.6. UPLC–MS/MS Analysis of Flavonoids

UPLC separation of flavonoid glycoconjugates in plant extracts was performed on an Acquity BEH C18 column (2.1 × 100 mm, 1.7 μm, Waters) using a Waters Acquity UPLC system. A linear gradient from 5% acetonitrile in 0.1% aqueous formic acid to 98% acetonitrile was applied over 12 min. A Xevo TQ-Smicro tandem mass spectrometer (Waters) in positive electrospray mode was used for quantification. Multiple reaction monitoring (MRM) parameters are detailed in Supplementary Materials Table S5. Aqueous ethanol extracts were diluted 100 times with reserpine (internal standard) solution (10 ng/mL) in 70% ethanol before MRM analyses. Calibration concentrations ranged from 50 ng/mL to 10 µg/mL for all analytes.