Validated RP-UHPLC PDA and GC–MS methods for the analysis of psychoactive alkaloids in Sceletium tortuosum

Abstract

Anecdotal evidence indicates that Sceletium tortuosum has been used as a psychoactive preparation for several centuries. The psychological activity is attributed to the production of mesembrine-type alkaloids (mesembrenol, mesembranol, mesembrenone and mesembrine) by the plant. This investigation was aimed at developing validated reversed phase ultra performance liquid chromatography with photodiode array detector (RP‐UHPLC PDA) and gas chromatography coupled to mass spectrometry (GC–MS) methods for quantitative assessment of mesembrine-type alkaloids in S. tortuosum raw materials and products. Both methods were validated for linearity, repeatability and recovery. Limits of detection (LOD) and limits of quantification (LOQ) for the alkaloids were also established. The LOD range for the RP‐UHPLC PDA analysis of compounds was 0.91–1.21 μg ml−1 , while the LOQ range was 2.72–3.71 μg ml−1 . For GC–MS analysis, the LOD and LOQ ranges for the compounds were 11.78–22.76 μg ml−1 and 35.34–68.29 μg ml−1 respectively. Regression analyses indicated good linear relationships for the investigated compounds. The regression coefficients (R2 ) from RP‐UHPLC PDA analyses ranged from 0.9977 to 0.9991, while those derived from GC–MS analyses were within the range of 0.9979 to 0.9995. Intra- and inter-day precision values for all the alkaloids were below 3.44% for RP‐UHPLC PDA and below 3.15% for GC–MS analysis, indicating excellent repeatability. Percentage recovery ranges for the four alkaloids as determined by RP‐UHPLC PDA and GC–MS analyses ranged from 80.00 to 89.83% and from 80.77 to 90.00%, respectively. Plots of RP‐UHPLC PDA data of selected raw materials and products versus GC–MS data, showed good linear correlation (R2 = 0.9820–0.9987). The chromatographic methods were found to be repeatable, precise and appropriate for use in the routine quality control of the psychoactive alkaloids in S. tortuosum raw materials and products. © 2012 SAAB. Published by Elsevier B.V. All rights reserved.