A sensitive UPLC-MS/MS method for simultaneous determination of polyphenols in rat plasma: application to a pharmacokinetic study of dispensing granule and standard decoction of Cinnamomum cassia twigs.

This study established a rapid and reliable approach using liquid chromatography-tandem mass spectrometry for the simultaneous determination of cinnamic acid, vanillic acid and protocatechuic acid in rat plasma. This is the first report on a comparative pharmacokinetic study of dispensing granules and standard decoction of Cinnamomum cassia twigs in rats. After liquid-liquid extraction by ethyl acetate, the plasma samples were subjected to LC-MS/MS for multiple reaction monitoring. The standard curves showed good linear regression (r(2) > 0.9991) in the range of 10.0-16000 ng/mL. The intra- and inter-day accuracy and precision were found to be within 15% of the nominal concentration. The recoveries of the three phenolics ranged from 88.7 to 105.7%. Finally, this approach was successfully applied to pharmacokinetic analysis of the three phenolics after oral administration of standard decoction and dispensing granules of C. cassia twigs in rats. Although the values of AUC(0-t) of vanillic acid and protocatechuic acid in standard decoction group were larger than those of the dispensing granule group, no significant difference was observed for the two groups. Of note, the elimination rates of vanillic acid were slower in the standard decoction group than the dispensing granule group.