Determination of fascaplysin in rat plasma with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC–MS/MS): application to a pharmacokinetic study

Abstract A rapid and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC–MS/MS) method was developed to determine fascaplysin in rat plasma using methylfascaplysin as an internal standard. Both fascaplysin and methylfascaplysin were synthesized in our laboratory. Protein precipitation was applied for the preparation of the plasma sample. Chromatographic separation was performed on a reversed-phase UPLC C18 column (1.8 μm, 100 mm × 2.1 mm) with a flow rate at 0.4 mL min −1 . A triple-quadrupole mass spectrometer was employed for multiple reaction monitoring (MRM) in positive ionization mode. The MRM ion transitions m/z 271.0 → 242.1 and m/z 285.1 → 270.1 were selected to determine fascaplysin and methylfascaplysin respectively. The calibration curves for fascaplysin quantification showed excellent linearity in the range of 1–500 ng mL −1 with a limit of lower quantification (LLOQ) of 1 ng mL −1 . The within-run and between-run accuracy ranged from 95.1% to 110.0% with precision lower than 7.4% in low, medium and high concentration levels for quality control (QC). The specificity, matrix effect, recovery, and stability were validated in accordance with the FDA bioanalytical method validation guidance. In the end, the proposed UPLC–MS/MS method was successfully applied in a pharmacokinetic study of fascaplysin after intravenous and intragastric administration to rats, which indicates a potential way for the preclinical study of fascaplysin in the future.