Quantification of β-eudesmol in rat plasma using LC-MS/MS and its application to a pharmacokinetic study

A sensitive and specific LC-MS/MS assay for determination of -eudesmol in rat plasma was developed and validated. After liquid-liquid extraction with ethyl ether, the analyte and IS were separated on a Capcell Pak C-18 column (50x2.0mm, 5m) by isocratic elution with acetonitrilewater-formic acid (77.5:22.5:0.1, v/v/v) as the mobile phase at a flow rate of 0.4mL/min. An ESI source was applied and operated in positive ion mode; a selected reaction monitoring scan was used for quantification by monitoring the precursor-product ion transitions of m/z 245.1163.1 for -eudesmol and m/z 273.481.2 for IS. Good linearity was observed in the concentration range of 3-900ng/mL for -eudesmol in rat plasma. Intra- and inter-day precision and accuracy were both within +/- 14.3%. This method was applied for pharmacokinetic studies after intravenous bolus of 2.0mg/kg or intragastric administration of 50mg/kg -eudesmol in rats.