Validation of a liquid chromatography ionspray mass spectrometry method for the analysis of flavanones, flavones and flavonols

The application of liquid chromatography/mass spectrometry (LC/MS) with a T urboIonspray (TIS) interface was investigated as a new method for the analy sis of flavonoids. Eleven compounds belonging to three different classes of flavonoids were studied: eriocitrin, neoeriocitrin, naringin, narirutin, h esperidin, neohesperidin (flavanone glycosides), quercetin, kaempferol, gal angin (flavonol aglycones), chrysin, apigenin (flavone aglycones), Chromato graphic separations were performed under reversed-phase conditions using a C18 narrow-bore LC column; a mixture of an aqueous solution of formic acid (pH 2.4) and acetonitrile was used as the mobile phase, Isocratic elution w as operated in the case of flavanones, whereas gradient elution was used fo r the simultaneous separation of flavones and flavonols, The adaptability o f TIS to high how applications allows the use of LC eluent flow rates at 20 0 mu L/min without post-column splitting. Qualitative analysis was performe d in negative-ion (NI) full-scan mode, whereas response linearity, detectio n limits and precision of the method were studied under NI selected ion mon itoring (SIM) conditions, Characterization of isomers differing in the glyc osylation was found to be possible on the basis of different mass spectra, Detection limits in the low-ng range (0.08-0.4 ng) were found, about twenty -fold lower than those reported previously. The method was applied to ident ify and determine the content of flavonoids in an orange juice sample. Copy right (C) 1999 John Whey & Sons, Ltd.