Spice Wars—Are You Battle Ready? Analysis of Synthetic Cannabinoids Using an HR-CI Source Operated in EI and CI Modes

Significance of the Topic

Synthetic cannabinoids have become pervasive in illicit drug markets due to their easy structural modification, perceived legality and limited detection by routine assays. Rapid and confident identification of these compounds is critical for forensic laboratories, quality control and public safety agencies.

Study Objectives and Overview

This application note details a comprehensive workflow for extraction, gas chromatography coupled with high resolution time of flight mass spectrometry (GC-HRT) and both electron ionization (EI) and chemical ionization (CI) acquisition to identify known and novel synthetic cannabinoids in seized botanical materials.

Experimental Methodology

Sample Preparation

• Biological matrix (30 mg) extracted with chloroform:methanol 2:1
• Vortexed for one minute, sonicated three minutes, filtered into GC vials

Instrumental Conditions

• GC: Agilent 7890, splitless injection at 250 °C, Rxi-5 MS column, temperature ramp 50 to 300 °C
• MS: LECO Pegasus GC-HRT
• Resolution: up to 50 000 FWHM, mass accuracy <1 ppm
• Ion sources: EI at 250 °C, CI (5 % NH3 in CH4) at 200 °C
• Mass range: 35–510 m/z (EI), 60–510 m/z (CI), acquisition rate 10 spectra per second
• Data processed using ChromaTOF with high resolution deconvolution; spectral searches against NIST and Wiley libraries

Instrumentation

Key components of the GC-HRT system include:

• Pegasus high resolution time-of-flight mass spectrometer
• High-resolution chemical ionization source capable of EI and CI in one platform
• ChromaTOF software with formula determination and isotopic pattern evaluation

Results and Discussion

Sample 1 (botanical extract) yielded peaks for XLR-11 and its fluoro isomer as confirmed by exact mass fragments and database matching. An unknown component displayed a protonated molecular ion at m/z 331.21276 (C18H27N4O2). Database searches in ChemSpider, Cayman Chemical and SWGDRUG narrowed candidates to AB-Pinaca. Accurate mass fragment ions supported the structural assignment.
Sample 2 (White Tiger packet) produced an abundant ion at m/z 312.20697 (C19H26N3O). Complementary CI data showed a protonated molecular ion at m/z 357.22870 (C20H29N4O2), leading to identification as AB-Chminaca. Neither compound was present in initial commercial libraries, highlighting the need for high resolution full scan data.

Practical Benefits of the Method

• Comprehensive full mass range acquisition enables retrospective data mining for emerging analogues
• High resolution and accurate mass ensure unambiguous formula determination for molecular and fragment ions
• Single-platform EI/CI source streamlines workflow for unknown screening and confirmation

Future Trends and Potential Applications

As novel designer drugs continue to evolve, integration of high resolution MS with advanced informatics, machine learning based spectral prediction and expanded curated libraries will be essential. Portable high resolution mass spectrometers, real-time screening at border checkpoints and automated suspect compound alerts represent promising developments.

Conclusion

The described GC-HRT EI/CI workflow delivers high quality accurate mass data for rapid identification of synthetic cannabinoids. The combined use of full scan acquisition, high resolution deconvolution and strategic database searching enables confident characterization of both known and novel psychoactive substances.

References

• Presley BC, Jansen-Varnum SA, Logan BK. Analysis of Synthetic Cannabinoids in Botanical Material: A Review of Analytical Methods and Findings. Forensic Science Review 2013;25:27–46.
• Krasowski MD, Ekins S. Using cheminformatics to predict cross reactivity of designer drugs to currently available immunoassays. Journal of Cheminformatics 2014;6:22.
• ChemSpider database, accessed December 2014.
• Cayman Chemical website, accessed December 2014.
• SWGDRUG database, accessed December 2014.