Quantitative analysis of xanthohumol and related prenylflavonoids in hops and beer by liquid chromatography tandem mass spectrometry

A method for quantitation of six prenylflavonoids (xanthohumol, isoxanthohu mol, desmethylxanthohumol, 6- and 8-prenylnaringenins and 6-geranylnaringen in) in hops and beer by HPLC-tandem mass spectrometry has been developed. T he method allows direct analysis of beer and crude methanolic extracts of h ops. After HPLC separation, prenylflavonoids were detected by positive ion multiple-reaction monitoring using a triple-quadrupole mass spectrometer eq uipped with a heated nebulizer-atmospheric pressure chemical ionization int erface. The accuracy and precision were evaluated by replicate analyses of (spiked) samples. Thirteen commercial beers were analysed with the method. Isoxanthohumol, formed by isomerization of xanthohumol during the brewing p rocess, was the most abundant flavonoid in hopped beers, ranging from 0.04 to 3.44 mg/l. (C) 1999 Elsevier Science B.V. All rights reserved.