Determination of visnagin in rat plasma by liquid chromatography with tandem mass spectrometry and its application to in vivo pharmacokinetic studies.

A rapid and sensitive method for the determination of visnagin in rat plasma was developed using liquid chromatography tandem mass spectrometry (LC-MS/MS). The plasma samples were processed by protein precipitation with methanol:acetonitrile (25:75) and warfarin was used as the internal standard. After vortex mixing and centrifugation, the supernatants were diluted with water (1:5) and then directly injected onto a Phenomenex Synergi Max RP column (75 mm x 2.0 mm ID, 4 microm) with isocratic elution at a flow rate of 0.2 mL/min. The mobile phase consisted of water and methanol (15:85, v/v) containing 0.1% formic acid and 5mM ammonium acetate. The total run time (injection to injection) was less than 4 min. Detection of the analytes was achieved using positive ion electrospray in the selected reaction monitoring (SRM) mode. The linear standard curve ranged from 1.0 to 5000 ng/mL and the precision and accuracy (inter- and intra-run) were within 4.5% and 4.3%, respectively. The method, which is rapid, simple, and precise, was successfully used to support a visnagin pharmacokinetics study.