Validated Liquid Chromatography-Electrospray Ionization Tandem Mass Spectrometric Method for Quantification of Milnacipranin Human Plasma for Pharmacokinetic Study: ARandomized, Open-Label, Two-Period, Comparative Crossover Study in Healthy Korean Male Volunteers

A sensitive and specific liquid chromatography combined with electrospray ionization (ESI) tandem mass spectrometry (LC-MS/MS) method, operating in the positiveionization mode, for quantifying of milnacipran in human plasma using milnacipran-d10 as internal standard (IS) was developed and validated. The analyte and IS were extracted by simple one step protein precipitation (PP). The chromatographic separation was performed on a Gemini C18 column (150 X 2.0 mm, 5 um) under isocratic conditions using a mixture of acetonitrile/0.1% formic acid (50:50, v/v) as mobile phase at a flow rate of 0.25 ml/min. Quantitation was performed using multiple reaction monitoring (MRM) mode to study parent → product ion transitions of m/z 247.2 →100.1 for milnacipran and m/z257.2→240.3 for IS, respectively. Linearity in plasma was obtained over the concentration range 2 ~ 500 ng/ml, with a coefficient of determination (r 2 ) of 0.9999. The method was has