Quantitation of 8-prenylnaringenin, a novel phytoestrogen in hops (Humulus lupulus L.), hop products, and beers, by benchtop HPLC-MS using electrospray ionization

8-Prenylnaringenin (8-PN), a potent phytoestrogen, present in hops (Humulus lupulus L.), hop products, and most beers, exhibits an estrogenic activity greater than that of any of the known phytoestrogens. A sensitive, selective, and robust analytical method, based on HPLC-MS (High performance Liquid Chromatography - Mass Spectrometry) using atmospheric pressure electrospray ionization, has been developed for systematic investigation of the development and the localization of this estrogenic trait in the hop plant, as well as for quantitative determination of 8-PN in hop varieties, hop products, and beers. Excellent linearity was obtained in the range of 3.7-2,200 mu g L-1 (gamma = 0.9999, n = 7) and the limit of detection was ca, 1 mu g L-1 Recoveries were between 93.8 % (110 mu g L-1) and 96.5 % (370 mu g L-1) for hop products, and between 63.4 % (18.5 mu g L-1) and 72.8 % (37 mu g L-1) for beers. Good precision was achieved with relative standard deviations of less than 5 % within-day (n = 6) and less than 10 % from-day-to-day (n = 18).