Rapid LC-MS/MS determination and pharmacokinetic application of linarin in rat plasma

A sensitive, selective and robust liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for the rapid determination of linarin in rat plasma. Separation of the analyte and warfarin as internal standard (IS) from 100 μL rat plasma was carried out by simple protein precipitation treatment. Chromatographic separation of the analyte was performed on a Diamonsil® C(18) column (150 × 4.6 mm, 5 µm) using isocratic mobile phase consisting of methanol-0.5% formic acid (80:20, v/v). The flow rate was 0.6 mL/min and the total run time was not more than 4.0 min. The method was validated over a wide dynamic concentration range of 1.00-1000 ng/mL for linarin. The precision and accuracy values for linarin met the acceptance criteria according to US Food and Drug Administration guidelines. Linarin was stable in the stability studies including a long-term test (-80°C for 43 days), a short-term test (ambient for 2 h and autosampler for 8 h) and three freeze-thaw cycles (-80-25°C). The developed assay method was applied to the pharmacokinetic study in rats after a single intramuscular administration of 713 µg/kg linarin.