GC-MS/MS method for the quantification of α-cedrene in rat plasma and its pharmacokinetic application.

α-Cedrene is a pharmacologically active ingredient isolated from the essential oil of cedar. A selective and sensitive GC-MS/MS method was developed for the quantification of α-cedrene in rat plasma for the first time. α-Cedrene was extracted from rat plasma using ethyl acetate at neutral pH. The analytes were determined in selective reaction monitoring mode using MS/MS: m/z 204.3→119.0 for α-cedrene and m/z 146.0→111.0 for 1,4-dichlorobenzene (internal standard). The standard curve was linear (r(2) ≥ 0.995) over the concentration ranges of 5-800 ng/mL. The lower limit of quantification was 5 ng/mL using 50 μL of rat plasma. The coefficient of variation and relative error for intra- and interassays at four quality control levels were 3.1-13.9% and -4.0-2.6%, respectively. The stability of processing (freeze-thaw, long-term storage at -80°C, and short-term storage at room temperature) and chromatography (reinjection) was shown to be of insignificant effect. The present method was applied successfully to the pharmacokinetic study of α-cedrene after its intravenous (10 mg/kg) and oral (25 mg/kg) administration in male Sprague-Dawley rats.