Liquid chromatography-tandem mass spectrometry for the quantification of flurbiprofen in human plasma and its application in a study of bioequivalence.

Abstract A simple, quick and accurate LC-MS/MS method for the quantification of flurbiprofen in human plasma with indomethacin as internal standard (IS) was developed and validated. Samples were treated with methanol to precipitate proteins, then separated on a Ultimate C 18 column (5 μm, 2.1 × 50 mm) with a gradient elusion process. Mobile phase A was comprised of water and formic acid, mobile phase B was comprised of acetonitrile and formic acid. Multi reaction monitoring (MRM) signals were saved on a negative ionization electrospray mass spectrometer. The calibration curve showed good linearity in the range of 40.00–10000.00 μg/L ( r 2  = 0.998). Intra-day RE was 0.2–2.2%. Inter-day RE was 0.5–3.4%. The samples showed good stability under the study conditions. No significant matrix effect was observed. The established method was then applied to a bioequivalence study of a flurbiprofen axetil formulation.