An LC-MS/MS Method for Determination of Imperatorin and Isoimperatorin in Rat Plasma and Application to a Pharmacokinetic Study

A highly sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for the de-termination of imperatorin and isoimperatorin in rat plasma using psoralen as internal standard. Analyses were performed on a Shimadzu HPLC system using a Shimadzu C18 column eluted with a mobile phase of methanol-water (25:75), containing 0.1% formic acid at a flow rate of 0.4 ml/min. The detection was performed by positive ion elec-trospray ionization in multiple reactions monitoring mode, monitoring the transitions m/z 203→147 and m/z 203→159 for imperatorin and isoimperatorin, respectively. The method was validated over the concentration range of 2.5 -1000.0 ng/mL for imperatorin and isoimperatorin. The limits of detection and quantification were 1.0 and 3.0 ng/mL, repectively for both analytes. The intra-day and inter-day accuracy and precision of the assay were less than 10.9%. This method has been applied successfully to a pharmacokinetic study involving the intragastric administration of extract of Angelicae Dahuricae Radix to rats.