Development and validation of a liquid chromatography-tandem mass spectrometry method for simultaneous quantification of eight Xiakucao Oral liquid-related compounds in rat plasma and its application in pharmacokinetic study.

Xiakucao Oral Liquid (XKCOL) has been widely used for treating mammary gland hyperplasia and goiter in China. However, its pharmacokinetic data have been missing to date. To conduct its pharmacokinetic study, we established an LC-tandem mass spectrometry method for the simultaneous determination of eight XKCOL-related compounds in rat plasma. Liquid-liquid extraction was used for the sampling process. Chromatographic separation was performed on a Phenomenon Luna C18 column with a mobile phase of methanol and 2 mM ammonium acetate, using gradient elution at a flow rate of 0.8 mL/min. Detection was performed in the multiple reaction monitoring mode using negative electrospray ionization (ESI-) with optimized MS parameters. Endogenous substances and carryover did not interfere in the detection of analytes. The calibration curves showed a good linear relationship within the linear ranges. The intra- and inter-batch accuracy and precision were 94.8%-110.0% and ≤11.2%, respectively. There was no significant matrix effect and the recovery was reproducible. The dilution of samples did not affect the accuracy and precision. The solution and plasma samples were stable under the various test conditions. The major components of XKCOL absorbed into the blood were salvianic acid A and rosmarinic acid. They demonstrated linear kinetics over the dose range used in this study.