RESUMEN
Aim: To establish an LC-MS/MS method to simultaneously determinate strychnine (STR), brucine (BRU), strychnine N-oxide(SNO) and brucine N-oxide(BNO) in rat tissue, and study their tissue distributions following single intragastric administration of total alkaloids from Semen Strychni at normal and high toxic dose. Methods: Ephedrine hydrochloride was used as the internal standard (IS). Analytes were extracted from tissue samples using liquid-liquid extraction with chloroform. Chromatographic separations were performed on a ZORBAX E-clipse XDB-C18 column(2.1 x 150 mm, 3. 5 μm) with the mobile phase of phase A(water, 10 mM ammonium acetate, adjusted to pH 4. 0 with formic acid) and B(methanol) at a flow rate of 0. 2 mL · min-1. The column temperature was maintained at 30 °C. Mass spectrometric detection was performed on an API4000+ triple quadrupole mass spectrometer equipped with an electrospray ionization (ESI) interface in the positive ion multiple reaction monitoring(MRM) mode. Results: Excellent linearity was observed in all analytes within their linear ranges. In-tra-and inter-day relative standard deviations (RSDs) were less than 14.90%, and accuracies were (85.94 ±1.43)% -(113. 77 ±5.19)%. STR, BRU and SNO distributed in all the tissues in different degree, among which content in kidney and liver was the richest. STR and BRU distributions were low in brain. Conclusions: The developed method is simple, sensitive, specific and reliable, which is suitable for simultaneous determination of STR, BRU, SNO and BNO in rat tissues.