Rapid determination of cannabinoids in edibles by thermal desorption GC/MS (

Importance of the topic

The reliable measurement of cannabinoids in edible products is essential for consumer safety, regulatory compliance, and quality control. Edibles present analytical challenges due to their complex matrices, which can interfere with extraction and detection. A rapid, solvent-free approach supports efficient testing in research, industrial QC, and regulatory laboratories.

Objectives and Study Overview

This technical note outlines a streamlined method for determining Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabinol (CBN) in a commercial cannabis-infused chocolate bar. The study applies thermal desorption (TD) combined with gas chromatography–mass spectrometry (GC/MS) and the standard addition calibration technique to address matrix effects and achieve accurate quantitation.

Instrumentation

• Multi-Shot Pyrolyzer® directly interfaced to a GC/MS injector
• UAD™-2.5N capillary tube for evolved gas analysis (EGA)
• UA-5+ capillary GC column (30 m × 0.25 mm i.d., 0.25 µm film)
• Vent-free GC/MS adapter and helium carrier gas

Methodology

1. Evolved gas analysis was performed on a 100 ppm THC standard from 100 °C to 800 °C at 20 °C/min to identify the optimal desorption window (100 °C–300 °C).
2. A 0.1 mg sample of chocolate (labeled 100 mg THC per 50 g) was placed in a pyrolysis cup.
3. Standard addition: spiking with 0, 100, and 300 ng of a 100 ppm methanol mixture (THC, CBD, CBN).
4. TD was conducted at 100 °C to 300 °C (100 °C/min, 1 min hold). GC oven ramped from 80 °C (2 min) to 320 °C at 20 °C/min (10 min hold).
5. MS scanned m/z 29–600 at 3 scans/s with a 1/20 split ratio.

Main Results and Discussion

Overlay chromatograms of spiked samples showed distinct peaks for CBD, THC, and CBN. A linear standard addition calibration for THC yielded an R² of 0.994. Calculated THC content was 2.10 mg/g (RSD 4.6%, n=3), matching the 2 mg/g label claim. The method demonstrated high precision, clear peak separation, and minimal sample preparation artifacts.

Practical Benefits and Applications

• No solvent extraction reduces preparation time and chemical waste.
• Standard addition corrects for matrix interferences in complex edibles.
• Rapid throughput supports high-volume testing in QA/QC settings.
• Applicable to a wide range of cannabis-infused products (chocolates, baked goods, edibles).

Future Trends and Opportunities

The integration of automated pyrolyzer sampling, miniaturized GC/MS systems, and high-throughput workflows will further accelerate edible analysis. Expansion to untargeted screening of minor cannabinoids and terpenes can provide comprehensive product profiles. Coupling TD-GC/MS with machine learning-based spectral deconvolution may enhance detection limits and specificity.

Conclusion

This study demonstrates a robust TD-GC/MS approach for direct, rapid quantification of major cannabinoids in a complex chocolate matrix. The method aligns with label claims, delivers reliable precision, and streamlines analytical workflows, making it suitable for routine industrial and regulatory applications.

References

• Frontier Laboratories Ltd. Technical Note PYA1-099E: Cannabinoid analysis in brownies.