Characterization of a Cannabinomimetic Compound in Synthetic Cannabis by Gas Chromatography-High Resolution Time of Flight Mass Spectrometry (GC-HRT)

Importance of the Topic

Sales of synthetic cannabis preparations pose significant public health and forensic challenges due to their rapidly changing compositions and limited representation in spectral libraries. Robust analytical approaches are essential to detect and identify these novel compounds in seized products labeled as herbal incense or potpourri but used for psychoactive effects.

Objectives and Study Overview

The main goal was to characterize the dominant unknown constituent in a commercially available “Mr. Smiley” incense product reported to induce cannabis-like highs. The study sought to extract active components, perform GC-TOFMS screening, and apply high resolution GC-HRT MS to assign accurate mass and ultimately identify the compound without reliance on existing spectral libraries.

Methodology and Instrumentation

Sample Preparation:

• One gram of the “Mr. Smiley” material was sonicated in 10 mL ethyl acetate for 10 minutes.
• A portion of the extract was transferred to autosampler vials for analysis.

Screening Analysis (GC-TOFMS):

• Instrument: LECO TruTOF HT coupled to Agilent 7890 GC.
• Column: Rtx-5, 10 m × 0.18 mm × 0.2 µm; He carrier gas at 1.5 mL/min.
• Oven program: 60 °C to 330 °C at 50 °C/min; injection 1 µL split 50:1 at 275 °C.
• Mass range: EI 40–550 m/z, CI 50–550 m/z; spectral rate 20 spectra/s.

High Resolution Analysis (GC-HRT):

• Instrument: LECO Pegasus GC-HRT with Folded Flight Path™ technology.
• Column: Rtx-1614, 20 m × 0.25 mm × 0.1 µm; same GC conditions as above.
• Electron impact mode, resolution 25,000 FWHM, acquisition delay 60 s, spectral rate 20 spectra/s.
• Accurate mass data processed by ChromaTOF-HRT™ for formula searching.

Main Results and Discussion

GC-TOFMS screening revealed several constituents, but the most abundant analyte lacked a match in the NIST 2008 library. Deconvoluted EI spectra showed a molecular ion at m/z 341, confirmed by CI spectra displaying [M+H]+ at m/z 342 and characteristic adducts. High resolution TOFMS analysis yielded an observed accurate mass of 341.17675 with <2 ppm error. Formula search ranked C24H23NO as the top candidate, consistent with the structure of 1-pentyl-3-(1-naphthoyl)indole (JWH-018), a synthetic cannabinoid receptor agonist.

Benefits and Practical Applications

• High resolution accurate mass measurements enable identification of novel or illicit compounds absent from commercial libraries.
• Combining EI and CI modes strengthens molecular ion confirmation.
• This workflow supports forensic laboratories in monitoring emerging synthetic cannabinoids in herbal products.

Future Trends and Applications

As synthetic cannabis analogs continue to evolve, forensic and quality control laboratories will increasingly require high resolution MS tools with fast formula searching capabilities. Future developments may include:

• Expanded accurate mass spectral databases for rapid suspect screening.
• Integration of tandem mass spectrometry for structural elucidation of new analogs.
• Automated data processing pipelines leveraging high resolution GC-MS and machine learning for pattern recognition.
• Portable or in situ high resolution instrumentation for field testing of herbal products.

Conclusions

The combination of GC-TOFMS screening and high resolution GC-HRT MS proved effective in identifying JWH-018 in an herbal incense matrix without prior library entries. Accurate mass data below 2 ppm error facilitated confident formula assignment, demonstrating the value of high resolution MS in forensic analysis of synthetic cannabinoids.