The cactus Lophophora williamsii (Lem.) J.M.Coult., otherwise known as peyote, is proposed to have been used by native North Americans for over five thousand years for its psychoactive properties and as a treatment for many different ailments including fever, pain, rheumatism, and wounds 1, 2. Mescaline, the phenethylamine‐type hallucinogen responsible for peyote's psychoactive effects, is capable of inducing states of altered consciousness and has been used extensively in various ceremonial rituals for millennia 3-5. However, in 1970, the U.S. Drug Enforcement Administration criminalized the possession and use of mescaline and L. williamsii specifically, with the introduction of the Controlled Substances Act, where it was listed as a Schedule I substance 6. Consequently, there has been a rise in the use of other mescaline‐containing cacti, including those of the Echinopsis genus. Some of the most popular, such as Echinopsis pachanoi (Britton and Rose) Friedrich and Rowley, Echinopsis peruviana (Britton and Rose) Friedrich and Rowley, and Echinopsis lageniformis (Forst.) Friedrich and Rowley, are sought after for their mescaline content, while new clones such as “psycho0” are touted as having high potency 7-10.

The rise in the recreational use of cacti species has resulted in an increasing need for analytical techniques that can be used to readily analyze and quantify their psychoactive components, most notably mescaline, for toxicological studies and other investigative purposes. While typical analytical techniques such as GC‐ or LC‐MS rightfully enjoy widespread use and acceptance for the analysis of drugs of abuse, the complex cactus matrix requires significant sample processing in order for methods using these techniques to be applied for detection and quantification of mescaline. These can include defatting, lyophilization, extraction, pH adjustment, and recrystallization steps, among others, prior to analysis 11-14. For example, one sample preparation method for analysis of mescaline in peyote by LC‐MS requires Soxhlet extraction with methanol at 40°C for 8 h, followed by rotary evaporation, resuspension in water, acidification, defatting twice with an organic solvent, alkalization, extraction twice with solvent, subsequent evaporation of the solvent, resuspension in methanol, and syringe filtering before analysis can occur 15. Another method reported the need for four extractions with diethyl ether over 24 h, five extractions with methanol–ammonia for 24 h, rotary evaporation, resuspension in methanol, and syringe filtering 16. In addition to the long run times, some methods have an additional requirement for derivatization 17, 18. Thus, there remains a need for the development of alternative methods for the facile and rapid detection and quantification of drugs such as mescaline within plant matrices, with more streamlined sample preparation steps.

Direct analysis in real time—high‐resolution mass spectrometry (DART‐HRMS) is one of the newer ambient ionization mass spectrometric methods that has entered the mainstream as a means for the rapid analysis of compounds in complex matrices. It features the use of a DART ion source which enables open‐air ionization of analytes. When the source is coupled to a high‐resolution mass spectrometer via an atmospheric pressure interface, mass spectra that reveal the presence of the protonated forms of a range of molecules are acquired within a few seconds. The open‐air analysis means that samples can be presented in their native state (i.e., gas, liquid, or solid), an attribute which potentially offers numerous advantages. While other ambient techniques may perform similarly, including direct‐injection electrospray ionization (DI‐ESI) 19, easy ambient sonic‐spray ionization (EASI) 20, and paper spray ionization (PSI) 21, DART‐HRMS, which is enjoying increasing use as a sample screening tool for forensic laboratories, offers extremely fast analysis times and minimal methods development. The approach has been shown to work well for the rapid direct analysis of very complex matrices, including whole botanical samples such as leaves or seeds, extracts, and other plant products 22-24. Additionally, common sample pretreatment steps that are a requirement of the technique used (such as enhancing the volatility of analytes of interest through sample derivatization) can be circumvented. However, relatively few reports have appeared demonstrating the exploitation of the capabilities of DART‐HRMS for the quantification of small molecules in complex matrices 25, 26. Furthermore, while it has recently been shown that DART‐HRMS can be used to quantify the content of a psychoactive compound (i.e. atropine) in seeds 27, it remains unknown whether the ease of this technique can be readily applied to cactus‐type matrices which are composed of chlorophyllaceous parenchymal tissue that is inherently quite different from that of seeds and other woody samples.

Here, we present a validated DART‐HRMS‐based method for the quantification of mescaline in Echinopsis spp. of forensic importance. It is also demonstrated that DART‐HRMS can be used as a rapid screening tool to determine the possible presence of mescaline simply by presenting the sample in its native form to the open‐air space between the DART ion source and mass spectrometer inlet. The results of the application of this validated method to the determination of the mescaline content of several commercially available Echinopsis spp. products are reported.