Detection of Cannabinoids in Oral Fluid with the Agilent 7010 GC-MS/MS System

Importance of the Topic

Oral fluid testing for cannabinoids has emerged as a noninvasive, easily collectible alternative to blood or urine analysis in forensic and workplace settings. With growing legalization of medicinal and recreational cannabis, rapid, sensitive, and reliable methods for quantifying Δ9-tetrahydrocannabinol (THC), its metabolites, and related cannabinoids in minute sample volumes are in high demand.

Study Objectives and Overview

This work describes the development of a fast, simple, and robust GC-MS/MS method using the Agilent 7010 system for simultaneous quantification of THC, 11-hydroxy-THC (OH-THC), 11-nor-Δ9-carboxy-THC (THCA), cannabidiol (CBD), and cannabinol (CBN) in 200 µL of oral fluid. The aim was to achieve low limits of quantitation (LOQ) and short analysis time (<10 min) while using standard electron ionization (EI) and a straightforward derivatization protocol.

Methodology and Instrumentation Used

Sample preparation involved SPE extraction of cannabinoids from oral fluid, followed by silylation with MTBSTFA to form stable derivatives. Analysis was performed on an Agilent 7890B GC coupled to a 7010 triple quadrupole MS with a Multi-Mode Inlet (MMI) in solvent-vent mode. Key parameters:

• Column: Agilent DB-5ms, 15 m × 0.25 mm, 0.25 µm
• Oven program: 80 °C (0.5 min) → 250 °C at 40 °C/min → 300 °C at 10 °C/min
• Ionization: EI at 280 °C source temperature
• Collision gas: Nitrogen; quench gas: Helium

Main Results and Discussion

All analytes exhibited linear response over at least 2.5 orders of magnitude with R² ≥ 0.992. LOQs were 0.20 ng/mL for THC, OH-THC, CBD, CBN and 0.015 ng/mL for THCA. Signal-to-noise ratios at LOQ exceeded 30:1 for most compounds. Normalized LOQs demonstrated competitive sensitivity compared with GC-NCI-MS/MS methods. Representative MRM chromatograms confirmed retention times at ~6.3 min for THC and ~9.0 min for THCA with consistent qualifier ratios.

Benefits and Practical Applications

This method delivers high specificity and sensitivity with minimal sample and reagent consumption. The rapid derivatization and short run time support high-throughput workflows. Laboratories lacking negative ion CI capabilities can implement this EI-based approach without major hardware modifications.

Future Trends and Potential Applications

Automation of SPE and derivatization using robotic workstations could further boost throughput. Expansion to broader cannabinoid panels or alternative matrices (e.g., sweat, breath) may extend applications. Emerging ambient ionization techniques and miniaturized MS systems may enable on-site screening at roadside or security checkpoints.

Conclusion

The presented GC-EI-MS/MS method using Agilent 7010 offers a streamlined workflow for reliable quantification of THC, its metabolites, and other cannabinoids in oral fluid. Its speed, sensitivity, and ease of adoption make it well suited for forensic, clinical, and workplace drug testing environments.

References

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