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 (r² ≥ 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.