Determination of pseudo-ginsenoside GQ in human plasma by high performance liquid chromatography-tandem mass spectrometry.

A specific, sensitive and rapid method based on high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) was developed for the determination of pseudo-ginsenoside GQ in human plasma. Liquid-liquid extraction was used to isolate the analyte from biological matrix followed by injection of the extracts onto a C8 column with isocratic elution. Detection was carried out on a triple quadrupole tandem mass spectrometer (API-4000 system) in multiple reaction monitoring mode using negative electrospray ionization. The mobile phase consisted of methanol-10 mM ammonium acetate (90:10, v/v) and the flow rate was 0.3 mL/min. The method was validated over the concentration range of 5.0-5000.0 ng/mL for plasma. Inter- and intra-day precisions (relative standard deviation) were all within 15% and the accuracy (relative error) was ≤ 9.4%. The lower limit of quantitation was 5.0 ng/mL. The pseudo-ginsenoside GQ was stable after 8 h at room temperature, 24 h at autosampler and three freeze-thaw cycles (from -30 to 25 °C). The method was successfully applied to the pharmacokinetic study of pseudo-ginsenoside GQ in healthy Chinese volunteers.