RESUMEN
Recently, there has been an increase in the recreational abuse of several psychoactive plants, resulting in the United Nations Office on Drugs and Crime creating a list of "plants of concern." One such material is Sceletium tortuosum and products derived from it. Regulation of these materials is challenging because of their innocuous appearance, the cumbersome sample preparation steps required to render the material into a form amenable to analysis by conventional techniques, the requirement for nuanced sample analysis protocols, and lengthy analysis times. It is demonstrated here that direct analysis in real time-high-resolution mass spectrometry (DART-HRMS) can be used to not only identify S. tortuosum material based on the detection of characteristic biomarkers including hordenine and several mesembrine alkaloids, but also quantify the amount of hordenine present. Using hordenine-d6 as an internal standard, a protocol, validated according to US Food and Drug Administration (FDA) Guidelines for the Development and Validation of Bioanalytical Methods, was devised for the quantification of the psychoactive component hordenine. The method was then applied to the quantification of hordenine in six commercially available products derived from the foliage and stems of S. tortuosum. By this method, the lower limit of quantification (LLOQ) was found to be 1 µg/ml. Observed hordenine concentrations ranged from 0.02738 to 1.071 mg of hordenine per gram of plant material. The developed technique provides an effective and quick means for the detection and quantification of hordenine in S. tortuosum, which can be extended to analysis of other hordenine-containing products.