Mariana Riccio (Universidade de Brasília, Brasil)
Abstract: Synthetic cannabinoids represent one of the most diverse classes of emerging psychoactive substances and are frequently seized in forensic operations. These substances, designed to mimic the effects of Δ9-tetrahydrocannabinol (Δ9-THC), exhibit diverse chemical structures, making their identification and quantification challenging using conventional methods. In this context, Nuclear Magnetic Resonance (NMR) spectroscopy has emerged as an advantageous analytical alternative, enabling structural characterization and accurate quantification without the need for commercial reference standards of the analyte itself. This study aimed to identify, quantify, and isolate the synthetic cannabinoids JWH-073, JWH-210, and JWH-250 from samples of plant material seized by the Brazilian Federal Police. For this purpose, gas chromatography-mass spectrometry (GC/MS) was used for the preliminary identification of cannabinoids in the samples, flash chromatography for separation, and NMR spectroscopy for characterization and quantification. The results obtained through NMR allowed for detailed structural characterization and confirmation of the identity of the cannabinoids JWH-073, JWH-210, and JWH-250, whose concentrations in the seized samples were 1.42%, 1.64%, and 0.87% (w/w), respectively. Additionally, purification via flash chromatography enabled the separation of the compounds with purities of 76.1% for JWH-073, 72.7% for JWH-210, and 89.0% for JWH-250. The data obtained demonstrate the efficiency of NMR as an analytical method for the quantification of synthetic cannabinoids, providing a reliable approach for forensic analysis without the need for commercial reference standards.
-
Hello Mariana, thank you for the nice presentation!
I have two questions :
1. At which magnetic field and with what range of concentration did you do your analysis of the mixture with?
2. I was wondering if this methodology could be used in the future to discriminate the origin of the seized material based on their cannabinoid composition?-
Hello! Thank you so much for your kind feedback and for your thoughtful questions!
1. Magnetic field and concentration range:
The NMR analyses were performed on a 14.1 T spectrometer (600 MHz for ¹H NMR). For the preparation of the samples, 100 mg of plant material was extracted with 1 mL of CDCl₃, resulting in a crude extract that was directly analyzed. The cannabinoid concentrations within this extract ranged from 1 to 3 mg/mL.2. Discriminating the origin of the seized material:
In an ideal scenario, yes — the cannabinoid composition could potentially be used to discriminate the origin of seized material, but it’d have to be supported by a comprehensive database and chemometric tools.In Brazil, for instance, the Federal Police runs a project called PeQui (Perfil Químico das Drogas), which focuses on establishing standardized chemical profiles of seized drugs to support forensic intelligence. This includes the analysis of purity, minor constituents, adulterants, and solvent residues to help identify trafficking routes, distribution patterns, and — when possible — infer geographic origin.
-
Thank you for your answers!
-
-
-
Hello,
I assume that these samples provided by the police were initially as plants (or plant parts). Could you describe the workup stages (extractions?) that are required to isolate the relevant compounds from the plant? Also, I think you are showing 1H NMR results only. Would adding 13C NMR data be useful to help increase your confidence in assigning the spectra to chemical compounds in the samples?
-
Hello, Cory! Thank you for your interest.
Yes, the samples provided by the Federal Police were plant materials — specifically herbal mixtures suspected to contain synthetic cannabinoids. Here’s a description of the extraction and isolation process for the enriched samples:
Extraction and isolation:
A total of 3.85 g of plant material, previously confirmed by GC/MS to contain a mixture of three synthetic cannabinoids, was extracted with 25 mL of methanol in a Falcon tube. The mixture was vortexed for 5 minutes, sonicated for 1 hour, and then centrifuged. The supernatant was collected, and the whole process was repeated another time under the same conditions. The combined extracts were evaporated at room temperature, yielding 165 mg of dry extract.This extract was then subjected to flash chromatography using a Biotage® Isolera One system, with a 10 g normal-phase silica column (25–33 µm). The elution was performed with an hexane/ethyl acetate mixture (95:5), allowing the isolation of enriched fractions of the cannabinoids for further analysis.
Regarding ¹³C NMR:
You’re absolutely right — while ¹³C NMR would certainly improve the confidence in compound identification, it was only feasible for the enriched fractions obtained through chromatography. In the crude extract, the analyte concentration was too low (~0.5-2%), and acquiring reliable ¹³C spectra would require prohibitively long acquisition times due to sensitivity limitations.-
Thank you for your responses.
-
-
-
Hi Mariana,
Thank you for your presentation, and I enjoyed it! I have two questions: 1. Have you tried using 2D NMR to further validate the structures of the different isomers? 2. This may not be directly related to the NMR focus of this conference, but have you considered getting crystals to precisely determine the structures? look forward to your thoughts.-
Hi Yunfan,
Thank you for your kind words and thoughtful questions!1. Regarding the use of 2D NMR: yes, we employed 2D experiments—specifically COSY, HSQC, and HMBC—to support the assignment of chemical shifts and confirm the substitution pattern of the isomers. These correlations were essential to distinguish between JWH-250 and its positional isomer JWH-201.
2. As for crystallography: although single-crystal X-ray diffraction would certainly provide definitive structural confirmation, we didn’t pursue it in this project. The combination of GC/MS and 1D/2D NMR already provided sufficient information to identify the structures with confidence. Moreover, growing suitable crystals from the isolated fractions would have been particularly challenging, both because of the small amount of material and the need for pure, well-formed single crystals. So considering the analytical goals and the limited sample availability, we prioritized solution-state NMR techniques.
Best regards,
Mariana
-
Leave a Reply