Determination of 20(S)-ginsenoside Rh1 and its aglycone 20(S)-protopanaxatriol in rat plasma by sensitive LC-APCI-MS method and its application to pharmacokinetic study

A liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS) method has been developed for the measurement of the concentrations of 20(S)-ginsenoside Rh1 and its aglycone 20(SI-protopanaxatriol in rat plasma with panaxatriot as the internal standard. The method involved single liquid-liquid extraction of both 20(S)-ginsenoside Rh1 and 20(S|-protopanaxatriol from plasma samples with n-butanol. The limit of quantification (LOQ) was 5ngmL^-1 for both compounds. The method was validated within the linear range 5-2000 ngmL^-1 for both compounds. The correlation coefficient for the calibration regression line was 0.999 or better. Intra-day and inter-day accuracy were better than 15%. The method has successfully been used for pharmacokinetic studies in rats. After intravenous administrations, the mean retention times of 20(S)-ginsenoside Rh1 and 20(S)-protopanaxatriot were 17.1±;2.0min and 3.66±0.33h, respectively.