Quantitative determination and pharmacokinetic study of solamargine in rat plasma by liquid chromatography–mass spectrometry

A sensitive and simple liquid chromatography–mass spectrometry (LC–MS) method has been developed and validated for the quantification of solamargine, a steroidal glycoalkaloid, in rat plasma. Vincristine was selected as the internal standard. Sample preparation involved simple liquid–liquid extraction by ethyl acetate with high efficiency. The chromatographical separation was performed on a Shimadzu C18 column (150 mm × 2.0 mm, 5 μm) with a gradient elution of acetonitrile and 0.02% (v/v) formic acid. The elutes were detected under positive electrospray ionization (ESI) and the target analytes quantified by selected ion monitoring (SIM) mode. The method was sensitive with the lowest limit of quantitation (LLOQ) at 0.5 ng/mL in 50 μL of rat plasma. Good linearity (r2 = 0.9996) was obtained covering the concentration of 0.5–2000.0 ng/mL. The intra- and inter-day assay precision ranged from 2.87 to 3.60% and 0.52 to 6.81%, respectively. In addition, the stability, extraction recovery and matrix effect involved in the method were also validated. The practical utility of the aforementioned method was successfully confirmed in the pharmacokinetic evaluation of solamargine in Sprague-Dawley rats after intravenous administration.