Isolation of quercetin and kaempferol from Rubus ulmifolius and their fluorometric assay

A fluorometric method for the determination of the flavonols quercetin and kaempferol in the leaves of Rubus ulmifolius was developed.A chromatographic technique for the isolation and separation of the two compounds was described. Working curves with standard solutions of quercetin and kaempferol at pH 2.5 were constructed. The effect of pH on the fluorescence intensity was studied with fluorescence measurements in acidic solutions of the compounds. The wavelengths for all fluorescence measurements were selected from fluorescence spectra of the two compounds.