Determination of flurbiprofen in rat plasma using ultra‐high performance liquid chromatography–tandem mass spectrometry and its application in a pharmacokinetic study

Abstract A rapid and sensitive ultra‐high performance liquid chromatography–tandem mass spectrometry method was developed to determine flurbiprofen in rat plasma. A triple quadrupole tandem mass spectrometer equipped with an electrospray ionization (ESI) source was used in negative ion mode. Acetonitrile precipitation was selected to prepare samples. Flurbiprofen and internal standard flurbiprofen‐d 5 were analyzed on an Acquity UPLC BEH C 18 column with the mobile phase consisting of acetonitrile and water, and a gradient procedure was used for separation. The retention time of flurbiprofen was 0.67 min, and the whole running time was only 1.2 min. The detection was performed on a triple quadrupole tandem mass spectrometer using multiple reaction monitoring mode via an ESI source with optimized mass spectrometry parameters. The calibration curve was linear in the range of 25.0–1.00 × 10 4 ng/mL ( r ≥ 0.99). The within‐run and between‐run relative standard deviations were not more than 13.9%. The within‐run and between‐run relative errors were from −9.0% to 3.4%. There was no significant matrix effect, and recovery was high. This method was fully validated, including whole blood stability in rat plasma, and successfully applied to the pharmacokinetic study in which 100% incurred sample reanalysis met the criteria.