AIM To develop a sensitive and rapid LC/MS/MS method for the determination of wogoni n, an active flavonoid shown to have an inhibitory effect on the proliferation o f a carcinoma cell line, in rat
plasma after an oral administration. METHODS
Wogonin and daidzein (internal standard) were extracted from plasma directly wit h n hexane diethyl ether (1∶4). After
liquid liquid extraction, the anal ytes of interest were separated on a Diamonsil C 18 column. The mobile phas e was acetonitrile water formic acid (80∶20∶1) with a flow rate of 0 8 mL ·min -1 . A Finnigan TSQ (triple stage quadruple) tandem
mass spectromete r equipped with an atmospheric
pressure chemical ionization (APCI) source was us ed as detector and was operated in positive ion mode. Selected reaction monitori ng (SRM) was used and transitions selected for quantitation were: m/z 284 8 →269 5 for wogonin and m/z 254 7→198 5 for daidzein. The mass spectrome tric conditions were as follows: The temperatures of the vaporizer and heated ca pillary were 450℃ and 250℃,
respectively. The corona discharge current was 4 00 μA. Nitrogen was used as the sheath and auxiliary gas, whose settings were 0 6 MPa and 3 mL·min -1 , respectively. Argon was used as the
collision gas at a pressure of 1 4 Pa. The collision energy of 35 V was chosen for both wogonin and daidzein. RESULTS The calibration curve was linear over the concentration range of 0 25 to 20 0 ng·mL -1 . The limit of quantitation was 0 25 ng·mL -1 . With in day and between day precision expressed by relative standard deviation (RSD ) was 2 2% to 13 1% and 5 9% to 7 3%, respectively, and the accuracy express ed by RE was -0 3% to 1 3%. CONCLUSION This method proved to be specific, accurate and sensitive enough to be applied t o the pharmacokinetic studies of wogonin in rats after a single dose of 5 mg· kg -1 by oral administration.
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