High-performance liquid chromatography-time-of-flight mass spectrometry with adjustment of fragmentor voltages for rapid identification of alkaloids in rat plasma after oral administration of Rhizoma corydalis extracts

A tandem high-performance liquid chromatography and time-of-flight mass spectrometry method has been developed for rapid separation and identification of alkaloids in rat plasma after oral administration of Rhizoma corydalis extracts. Compounds were separated on a Zorbax XDB-C-18 column and the linear gradient elution was used with the mobile phase consisting of ammonium acetate 0.01% acetic acid and acetonitrile. Mass spectra were acquired by electrospray ionization in the positive ion mode. Fifteen components were detected in vitro, among which 12 components were rapidly identified based on the accurate-mass capability of time-of-flight analyzer. Eleven prototype components were detected in dosed rat plasma (in vivo). Three isomers, which had the same [M+H]+ ion at m/z 356.1856, were distinguished as glaucine, tetrahydropalmatine, and corybulbine by dynamic adjustment of fragmentor voltages. This study developed a rapid and sensitive method that was successfully utilized for screening the active ingredients of Rhizoma corydalis in rat plasma, which provided helpful information for further pharmacokinetic research of active components in this medicine.