Development and validation of a solid phase extraction and LC-MS method for the determination of caulophine in rat plasma and tissue: Application to study its pharmacokinetics

A rapid and sensitive liquid chromatography-mass spectrometric (LC-MS) method was developed for investigating the pharmacokinetics of caulophine in rats. Biological samples were isolated by solid phase extraction (SPE) and analyzed by the LC-MS. A Shimadzu C18 VP-ODS column (150mm × 2.0mm ID, 5 μm) was used as the analytical column, with methanol-water-formic acid (33:67:0.1) as the mobile phase and a flow rate of 0.2mL/min. Within-day and between-day precision was 1.40-3.49% and 1.29-6.91%. Average recoveries for all matrices were greater than 85.0%. The main pharmacokinetic parameters were T_max=(0.84±0.31) h, C_max=(0.22±0.08) μg/mL, AUC=(0.87±0.16) h·μg/mL.