Analysis of iso-α-acids in alcoholic beverage

Detection of hop bittering components, iso-α-acids, in human plasma was carried out in order to prove the ingestion of beer. Three iso-α-acids, isocohumulone, isohumulone and isoadhumulone, were extracted from plasma with isooctane under acidic condition, and submitted to high-performance liquid chromatography. The components were well separated by octadecylsilica column using a mobile phase of methanol-water (77.5:22.5) containing 85% phosphoric acid (1.7g/100ml), 10% tetraethylammonium hydroxide (1g/100ml). Since isocohumulone and isohumulone were detected in beer as major components of iso- α-acids, these components were considered to be useful indicator to prove ingestion of beer.