[Analysis of ephedrine and its metabolites in rat urine by HPLC-ESI-ITMSn]

Abstract

Aim: To estabilish a rapid and sensitive LC-ESI-ITMSn method for the identification of ephedrine and its main metabolites in rat urine.

Methods: After optimizing the detection condition of LC-ESI-ITMSn chromatography and mass spectrometry by using a standard ephedrine, the ionization and cleavage rules of ephedrine in ESI-MS and ESI-MSn modes were summarized, and then serving as the basis for the metabolite analysis of ephedrine in rat urine. Rat urine samples of 0-48 h were collected after ig 10 mg x kg(-1) ephedrine, then the samples were purified through C18 solid-phase extraction cartridge. The purified samples were analyzed by LC-ESI-ITMSn.

Results: The structures of ephedrine metabolites were elucidated according to the changes of the molecular weights of the metabolites (deltaM) and their cleavage pattern in ESI-ITMSn. As a result, three phase I metabolites and the parent drug ephedrine were identified existing in rat urine, but no phase II metabolites were found.

Conclusion: The LC-ESI-ITMSn method is rapid and highly sensitive and sepecific, it is suitable for the identification of ephedrine and its metabolites in rat urine.