Study on the aconitine‐type alkaloids of Radix Aconiti Lateralis and its processed products using HPLC‐ESI‐MS n

The type and content change of alkaloids of Radix Aconiti Lateralis (Lateral root of Aconitum carmichaeli Debx , an important and popular medicinal herb in Traditional Chinese Medicine) in processing were studied using high performance liquid chromatography‐electrospray ionization‐multi‐stage mass spectrometry (HPLC‐ESI‐MS n ). Extract containing alkaloids, which were known to be the main bioactive components of the herb, was prepared by 1% ( v/v ) hydrochloric acid solution. An HPLC method which can simultaneously separate these alkaloids was established with gradient elution mode. Forty‐eight compounds were structurally identified by employing LC‐MS n techniques; the MS n spectra of most alkaloids displayed a characteristic behaviour of loss of CH 3 COOH (60 u), CH 3 OH (32 u), C 6 H 5 COOH (122 u), CO (28 u) and H 2 O (18 u). Among them, the fragmentation ion C6H5COOH (122 u) was reported for the first time. By comparison, 22 compounds were found both in the crude materials and the processed products; 17 alkaloids were only found in the processed products and 9 alkaloids,which existed in crude material, could not be detected after processing. In the process of identification, we found new kinds of alkaloids, with protonated molecules at m/z 452, 468, and 482. We called these compounds dehydra‐hypaconine, dehydra‐mesaconine, and dehydra‐aconine, respectively. Copyright © 2012 John Wiley & Sons, Ltd.