Profiling and quantitation of alkaloids in different parts of Sophora alopecuroides L. extracts by high‐performance liquid chromatography with electrospray ionisation ion mobility spectrometry detection

Abstract Introduction Ambient pressure electrospray ionisation ion mobility spectrometry coupled to high‐performance liquid chromatography (HPLC) was used to detect alkaloids from different parts of Sophora alopecuroides L. extracts. Multiplexing ion mobility spectrometry (IMS) was used to improve the signal‐to‐noise ratio while maintaining high resolving power for the detecting of eluents from HPLC separation. Material and methods The alkaloids profile and distribution are demonstrated by retention time‐drift time two‐dimensional spaces, and the contents of five major alkaloids including sophoridine, sophocarpine, cytisine, aloperine, and matrine were determined in the leaf, skin, stem, seed kernel, and seed husk using the HPLC‐IMS method. This method offers extra separation ability to isomers such as matrine and sophocarpine, which can be difficult to distinguish by mass spectrometry. Results The reduced mobilities for cytisine, sophoridine, sophocarpine, matrine, and aloperine are 0.828, 0.718, 0.731, 0.725, and 0.769 cm 2 /V/s, respectively. The limits of detection are 0.553, 0.488, 0.479, 0.484, and 0.513 ug/mL. This method adds extra separation ability to HPLC to resolve co‐eluted peaks and provides another qualitative parameter besides HPLC retention time.