5.4. Flavonol Glycoside Separation

To identify flavonol glycosides in ramps, a separation protocol first had to be developed. UHPLC-PDA was conducted using an Accela system (Thermo Scientific, San Jose, CA, USA) consisting of an Accela 1250 pump, open autosampler, and PDA detector. Flavonol chromatographic separation was performed on a Luna Omega 1.6 μm Polar C18 100 Å LC column with dimensions of 150 × 2.5 mm (Phenomenex, CA, USA) at 35 °C. The flow rates of 300 and 500 µL/min were tested. Gradient elution rates of a mobile phase for solvent A [5% formic acid in distilled water (v/v)], and solvent B [5% formic acid in acetonitrile (v/v)] were adjusted as shown in Table 3. Mobile phase solvents were selected based on a previously reported method [51]. An injection volume of 5 µL was held consistent throughout different methods. Flavonols were detected under a wavelength of 350 nm.

Mobile phase gradient elution of different flow rates and gradient elution times.