Simultaneous analysis of alkaloids from Zanthoxylum nitidum by high performance liquid chromatography–diode array detector–electrospray tandem mass spectrometry

The chemical profiles of nine alkaloids in Zanthoxylum nitidum, including berberubine, coptisine, sanguinarine, nitidine, chelerythrine, liriodenine, 6,7,8-trimethoxy-2,3-methylendioxybenzophenantridine, oxyavicine and dihydrochelerythrine, were identified by using high performance liquid chromatography–diode array detector–electrospray tandem mass spectrometry (HPLC–DAD–ESI–MS), and a novel and sensitive HPLC–UV method had been developed to simultaneously determine these alkaloids in 70% methanol extract of Zanthoxylum nitidum. The chromatographic separation was performed on an Agilent C18 analytical column (5 μm, 4.6 mm i.d., 250 mm length) with a gradient solvent system of acetonitrile–0.1% formic buffer (adjusted to pH 4.5 with triethylamine). The methodological validation was carried out and the linearities (r2 > 0.9997) and recoveries (ranged from 98.3% to 101.1%) were acceptable. The limits of detection (LOD) of these alkaloids were ranged from 0.6 ng to 1.5 ng. The results indicated that the contents of alkaloids in Zanthoxylum nitidum varied significantly from habitat to habitat with contents ranged from 0.03 mg/g to 3.34 mg/g. The proposed method is simple, effective and suitable for the quality control of this traditional Chinese medicine (TCM). It suggests that it is necessary to control its quality so as to insure efficacy and safety of TCM.