Cannabis Analysis: Hemp Potency Determination

Significance of the Topic

The legalization of hemp as an agricultural commodity and the proliferation of CBD products demand reliable, sensitive methods to measure psychoactive Δ9-THC levels for regulatory and safety purposes.

Study Objectives and Overview

This application note from LECO evaluates microwave-assisted extraction and GC-TOFMS for quantitative determination of total Δ9-THC, CBD, and CBN in certified reference material and commercial hemp samples to assess compliance with the US 0.3% Δ9-THC legal limit.

Methodology and Instrumentation

• Sample Extraction: 0.05 g ground hemp mixed with tribenzylamine (TBA) internal standard in ethanol, purged with N₂, and decarboxylated at 180 °C for 30 min via microwave-assisted extraction.
• Calibration: Seven-point standards (1–80 ng/µL) prepared with TBA and cannabinoid stock, yielding linearity (R > 0.997) for CBD, Δ9-THC, and CBN.
• Data Processing: ChromaTOF software with Target Analyte Finding (TAF) for deconvoluted peak detection using two diagnostic ions per analyte.

Instrumentation Used

• Agilent 7890 GC with LECO L-PAL 3 autosampler
• LECO Pegasus BT Time-of-Flight Mass Spectrometer
• Rxi-5 MS column (30 m×0.25 mm×0.25 µm)
• Microwave reactor for extraction

Main Results and Discussion

• Calibration curves exhibited excellent linearity (R > 0.997) for all three cannabinoids.
• Sample 1 Δ9-THC matched the certificate, while samples 2 and 3 exceeded distributor values; sample 3 (0.58 %Eq.) surpassed the US legal threshold.
• Deconvolution via GC-TOFMS and TAF ensured selective, interference-free identification, even in complex matrices.
• Untargeted analysis revealed additional cannabinoids and terpenes (e.g., caryophyllene, cannabigerol) with spectral similarity scores >800, expanding the chemical profile.

Benefits and Practical Applications

• The integration of microwave-assisted extraction and GC-TOFMS delivers high sensitivity and selectivity for routine potency testing.
• Automated deconvolution and dual targeted/untargeted workflows streamline laboratory efficiency and resource utilization.
• Comprehensive profiling supports quality control, product development, and safety assessment in pharmaceutical and industrial contexts.

Future Trends and Opportunities

• Method expansion to emerging cannabinoids, terpenes, and terpenoids for therapeutic and research applications.
• Standardization and cross-laboratory validation to harmonize regulatory testing worldwide.
• Integration with high-throughput data analytics and machine learning for advanced chemometric profiling.
• Longitudinal studies on dosing, bioactivity, and long-term safety of minor cannabis constituents.

Conclusion

GC-TOFMS combined with microwave-assisted extraction and advanced deconvolution offers a robust platform for accurate Δ9-THC quantitation and broad-spectrum chemical characterization of hemp, enhancing compliance and operational productivity in analytical laboratories.

Reference

• US Department of Agriculture. Establishment of a Domestic Hemp Production Program; 2019.
• H.R.5485—Hemp Farming Act of 2018.
• Congressional Research Service. Defining Hemp: A Fact Sheet; 2019.
• United Nations Office on Drugs and Crime. Recommended methods for the identification and analysis of cannabis and cannabis products; 2009.
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