A rapid and sensitive LC-MS/MS method for quantification of 3,29-dibenzoyl rarounitriol in rat plasma: application to a pharmacokinetic study

A rapid, sensitive and high-throughput liquid chromatography-tandem mass spectrometry was established and validated to assay the concentrations of 3,29-dibenzoyl rarounitriol in rat plasma. Plasma samples were processed by liquid-liquid extraction with ethyl acetate and separated on a Hypersil Gold C18 column (50 × 4.6 mm, 3 µm) at an isocratic flow rate of 0.5 mL/min using methanol-10 mm ammonium acetate-formic acid (90:10:0.1, v/v/v) as mobile phase. The total run time was 5 min for each sample. MS/MS detection was accomplished in selected reaction monitoring mode with positive electrospray ionization. The calibration curve was linear over the concentration range of 0.125-50 ng/mL with lower limit of quantification of 0.125 ng/mL. The intra- and inter-day precisions were <10.1% in terms of coefficient of variation, and the accuracy was within ±11.7% in terms of relative error. The developed method was successfully applied to a pharmacokinetic study of 3,29-dibenzoyl rarounitriol following intragastric administration of 3.65 mg/kg to Wistar rats.