Quantitative determination of helicid in rat plasma by liquid chromatography-electrospray ionization mass spectrometry and its application to preliminary pharmacokinetic studies

A sensitive and selective liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) method was developed for the identification and quantification of helicid in rat plasma. The method was based on simple liquid-liquid extraction (LLE). A Kromasil C18 column (150 mm × 2.00 mm, 3.5 μm) was used as the analytical column, while a mixture of acetonitrile and 500 μM ammonium chloride was used as the mobile phase. MS detection was performed using a single quadrupole mass spectrometer in a negative selected ion monitoring (SIM) mode. The deprotonated molecules [M + Cl]^- at m/z 319.00 and 363.05 were used to quantify helicid and bergeninum (internal standard, I.S.), respectively. The lower limit of quantification of helicid was 1 ng/ml. The method was linear in the concentration range of 1-1000 ng/ml. The intra-day and inter-day precisions (R.S.D.%) were within 10.0% for the analyte. Helicid proved to be stable during all sample storage, preparation and analytical periods. The method was successfully applied to a pharmacokinetic study in rats after intragastric administration of helicid with a dose of 50 mg/kg. Only 50 μl of rat plasma at each sampling time was needed for analysis. The proposed method enables unambiguous identification and quantification for the preliminary pharmacokinetic studies of helicid.