LC-MS determination and pharmacokinetic studies of paeonol in rat plasma after administration of different compatibility of Su-Xiao-Xin-Tong prescriptions.

A rapid and specific liquid chromatographic/electrospray ionization mass spectrometric (LC/ESI-MS) method has been developed and validated for the identification and quantification of paeonol in rat plasma. Paeonol and internal standard were isolated from plasma samples by liquid-liquid extraction with chloroform. The chromatographic separation was accomplished on a Zorbax-SB C18 column (100x2.1 mm, 3.5 microm). The mobile phase consisted of acetonitrile and 0.1% aqueous formic acid (64:36) was delivered at a flow rate of 0.2 mL/min. Detection was performed on a single quadrupole mass spectrometer by selected ion monitoring mode via electrospray ionization source. Linearity was established for the range of concentrations 0.0525-15.8 microg/mL with a coefficient correlation (r) of 0.9995. The intra- and inter-day precision (RSD%) was lower than 9.34% and accuracy ranged from 93.7 to 102.3%. The lower limit of quantification was 0.0525 microg/mL. The proposed method was used to determine the concentration of paeonol for pharmacokinetic studies. The pharmacokinetics of different compatibility prescriptions of Su-Xiao-Xin-Tong were studied and compared.