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

Importance of the Topic

Synthetic cannabis products marketed as “herbal incense” or “spice” pose significant analytical challenges due to their ever-evolving structures and the appearance of novel cannabinoids that are not represented in existing mass spectral libraries. Accurate identification of these compounds is essential for forensic laboratories, regulatory agencies, and public health authorities to enforce legislation, understand potential health risks, and monitor illicit markets.

Objectives and Study Overview

This study aimed to characterize unknown cannabinomimetic compounds in a commercially available product known as “Mr. Smiley,” which was linked to cannabis-like psychoactive effects. The primary goals were to detect and identify synthetic cannabinoids present in the sample using gas chromatography coupled to both time-of-flight mass spectrometry (GC-TOFMS) and high-resolution time-of-flight mass spectrometry (GC-HRT).

Methodology

A portion of “Mr. Smiley” incense was extracted with ethyl acetate following sonication. The extract underwent initial screening by GC-TOFMS to generate total ion and analytical ion chromatograms for compound detection and library searching. The most abundant unknown peak, absent from standard spectral databases, was subjected to further high-resolution analysis. Chemical ionization experiments with methane reagent gas confirmed molecular ion assignments.

Used Instrumentation

• GC-TOFMS: Agilent 7890 gas chromatograph with Rtx-5 column (10 m × 0.18 mm × 0.2 μm), LECO TruTOF HT mass spectrometer, electron ionization at 70 eV, mass range 40–550 m/z, acquisition rate 20 spectra/s.
• GC-HRT: LECO Pegasus GC-HRT with Folded Flight Path™ (FFP) technology, Rtx-1614 column (20 m × 0.25 mm × 0.1 μm), high-resolution mode (25,000 FWHM) and ultra-high mode (50,000 FWHM), accurate mass acquisition 10–1500 m/z.
• Software: ChromaTOF and ChromaTOF-HRT for data acquisition, deconvolution, and accurate mass formula searches.

Main Results and Discussion

GC-TOFMS screening revealed a dominant peak at retention time ~315 s that lacked a match in the NIST 2008 library. Electron impact and methane CI spectra localized the molecular ion at m/z 341 and confirmed [M+H]+ at m/z 342. High-resolution measurements on the Pegasus GC-HRT delivered an observed exact mass of 341.17675 with −1.95 ppm deviation for the formula C24H23NO. Literature comparisons and formula searches identified the compound as 1-pentyl-3-(1-naphthoyl)indole (JWH-018), a synthetic cannabinoid receptor agonist originally synthesized for receptor studies.

Benefits and Practical Applications

• High-resolution accurate mass data enable identification of novel or emerging synthetic cannabinoids absent from commercial libraries.
• Rapid screening by GC-TOFMS followed by targeted GC-HRT analysis streamlines forensic workflows.
• Method supports law enforcement and regulatory agencies in monitoring and controlling illicit herbal products.

Future Trends and Opportunities

As the variety of synthetic cannabinoids continues to expand, forensic laboratories will require high-resolution mass spectrometers with flexible resolution modes to keep pace with new analogs. Integration of accurate mass libraries, suspect screening workflows, and automated formula searches will enhance the ability to detect and characterize future cannabimimetic compounds.

Conclusion

The combined use of GC-TOFMS for initial detection and GC-HRT for accurate mass determination successfully identified JWH-018 in a “Mr. Smiley” incense sample. High-resolution mass spectrometry proved indispensable for detecting novel synthetic cannabinoids not present in standard spectral databases, demonstrating its value for forensic and regulatory applications.

Reference

1. Binkley J, Siek K, Fix C, Artaev V. Characterization of Cannabinomimetic Compounds in Synthetic Cannabis Products by Gas Chromatography—High Resolution Time-of-Flight Mass Spectrometry. LECO Corporation, St. Joseph, MI.