High-performance liquid chromatography with electrospray ionization mass spectrometry and diode array ultraviolet detection in the identification of flavonol aglycones and glycosides in berries.

High-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) was used to study flavonol aglycones and glycosides in berries. For the identification of aglycones, photodiode-array detection (DAD) was also used. The HPLC-ESI-MS technique is highly valuable in the identification of flavonol aglycones and glycosides from berry extracts. This ionization technique provides information on the structure of the aglycones and glycosides without time-consuming pre-purification or derivatization steps. Quercetin aglycone was identified with both ESI-MS and DAD in all of the berries studied. Myricetin aglycone was identified with both techniques in three berries. Hexose, deoxyhexose-hexose and pentose derivatives of quercetin were the most abundant flavonol glycosides identified. Two glycosides of myricetin and one glycoside of kaempferol were identified in blackcurrant. To confirm the data obtained using the HPLC-ESI-MS procedure, fractions of the glycosides from four berries were separated, hydrolyzed, silylated and the sugars were analyzed using gas chromatography-mass spectrometry.