Analysis of geniposidic acid and caffeine in leaves of Eucommia ulmoides used in health foods

An HPLC method was developed for the determination of geniposidic acid (GA) and caffeine (CF) in leaves of Eucommia ulmoides used in health foods. GA and CF in dried leaves were simultaneously extracted with water under reflux by heating. The extract was cleaned up with a C18 and ion-exchange type cartridge, then GA and CF were separated on an ODS column, with a UV detector (GA, 240 nm; CF, 275 nm). The recoveries of GA and CF added to samples were 94.2 similar to 94.7% and 90.4 similar to 96.7%, respectively. The determination limits of GA and CF in dried leaves were 10 mu g/g, and those in beverage samples were 1 mu g/g. The GA and CF contents of 15 commercial samples were surveyed. The contents of GA in dried leaves of only Eucommia ulmoides, in mixtures of dried leaves of Eucommia ulmoides and others, and in beverage samples, were 290 similar to 1,500, 160 similar to 1,300 and 3.6 similar to 19 mu g/g, respectively, while CF was only detected in the mixtures with leaves of green tea or oolong tea, at 2,100 similar to 9,800 mu g/g.