Determination of quercetin, isorhamnetin in buckwheat pollen

Flavonoids in buckwheat were extracted by refluxing with methanol. Quercetin, isorhamnetin in extract was determined by HPLC after the hydrolysis of all flavonol glycosides into aglycones. The mobile phase consisted of solvent A (methanol) and solvent B (phosphoric acid, pH5.12) for gradient elution. The flow rate was 1 mL/min and detection was effected at 368 nm. The results show that the content of quercetin and isorhamnetin in every gram of buckwheat pollen were 4.9 mg, 0.63 mg, respectively.