A simple HPLC method for quantitation of quercetin in herbal extracts.

A reversed-phase HPLC method with UV detection was developed for the determination of quercetin. The method produced linear response over a wide concentration range, with an average accuracy of 95% and average intra- and interday variation of 0.75 and 0.3, respectively. The exactness of the method was proven by determining the recovery rates from 50 to 150% of standard concentration, which were found within the acceptable range of 95 to 105%. The method was used for quantitation of quercetin in the extracts of Psidium guajava, Vitis vinifera, and extracts rich in quercetin and other flavonols in the flavonoid family.