Simultaneous determination of Guanfu base G and its active metabolites by UPLC-MS/MS in rat plasma and its application to a pharmacokinetic study

To establish a rapid and sensitive ultra performance liquid chromatography mass spectrometry (UPLC-MS/MS) method for the determination of concentration of guanfu base G (GFG) and its active metabolites in rat plasma. The GFG and its active metabolites and the internal standard (phenacetin) were separated on an Acquity UPLC (R) BEH C18 chromatography column (2.1 mm x 50 mm I.D., 1.7 mu m) using gradient elution with a mobile phase of methanol and ultrapure water at a flow rate of 0.4 mL/min. The detection was performed on a Xevo triple quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) mode to monitor the precursor-to-product ion transitions of m/z 472.26 -> m/z 310.03 for GFG and m/z 180.00 -> m/z 109.99 for phenacetin (IS) using a positive electrospray ionization interface. The lower limit of quantification (LLOQ) was 1 ng/mL, the limit of detection (LOD) was 0.3 ng/mL, and the linear calibration curve was obtained over the concentration range of 1-200 ng/mL. The intra-day and inter-day assay variations were measured to be below 10.97%, and the accuracy values (relative error) ranged from 95.4% to 103.6%. After validation, this method was successfully applied to a pharmacokinetic study where rats were intravenous administration of 5 mg/kg GFG. A simple, rapid, sensitive, and accurate method for the determination of the concentration of GFG and its metabolites in rat plasma was developed and validated. (C) 2014 Elsevier B.V. All rights reserved.