Characterization and determination of six aristolochic acids and three aristololactams in medicinal plants and their preparations by high-performance liquid chromatography-photodiode array detection/electrospray ionization mass spectrometry.

Aristolochic acid derivatives (AAs) and aristolactam derivatives (ALs) have been characterized by electrospray ionization mass spectrometry, and their fragmentation pathways are proposed. ALs exhibit a single ionization product [M+H]+, whereas AAs show multiple ionization products. By optimizing the chromatographic separation and mass spectrometric parameters, the precursor ions of the derivatives with the best responses were found, and the sensitivities in the determination of the nine derivatives were improved. Based on the investigation of ionization behaviour, a HPLC-DAD/ESI-MS (high-performance liquid chromatography-photodiode array detection/electrospray ionization mass spectrometry) method has been developed for simultaneous analysis of nine derivatives, i.e., AA I, AA II, AA C, AA D, 7-OH AA I, aristolic acid I, AL AII, AL IIIa and AL IVa, in nine medicinal herbs and two preparations. The method appears to be suitable for safety assurance and quality control of commercially available samples with good selectivity and suitable sensitivity.