Development of a sensitive LC-MS/MS method for simultaneous quantification of eleven constituents in rat serum and its application to a pharmacokinetic study of a Chinese medicine Shengmai injection.

A sensitive LC-MS/MS method was developed and validated for simultaneous quantification of 11 constituents, ginsenoside Rg1, Re, Rf, Rg2, Rb1, Rd, Rc, ophiopogonin D, schisandrin, schisandrol B and schizandrin B, in rat serum using digoxin as the internal standard (IS). The serum samples were pretreated and extracted with a two-step liquid-liquid extraction. Chromatographic separation was achieved on a C18 analytical column with a proper gradient elution using 0.02% acetic acid aqueous solution and 0.02% acetic acid-acetonitrile as mobile phase at a flow rate of 0.5 mL/min. MS detection was performed using multiple reaction monitoring via an electrospray ionization source. Good linearity was observed in the validated concentration range for every analyte (r(2) ≥0.9929), and the lower limits of quantitation of the analytes were in the range of 0.044-1.190 ng/mL in rat serum. Intra- and inter-day precisions were <14.2%. The accuracy expressed as recovery was within the range of 85.1-112.8%. The extraction recoveries were >75.8%.The validated method was successfully applied to a pharmacokinetic study of all analytes in rats after single intravenous administration of Shengmai injection.