HPLC separation of flavonols, flavones and oxidized flavonols with UV-, DAD-, electrochemical and ESI-ion trap MS detection

The cation-induced or electrochemical oxidation of flavonols has been repor ted to yield 2-(hydroxybenzoyl)-2-hydroxy-3(2H)-benzofuranones. Two new gra dient reversed phase HPLC methods are presented which allow the determinati on of those oxidized flavonols simultaneously with flavonols and flavones. UV and electrochemical detection are used because of their high sensitivity . Qualitative detection together with quantification of all compounds is ac hieved with photodiode-array detection. An electrospray ionization ion trap mass spectrometric method is presented for unique identification of the be nzofuranones after HPLC separation.