Analysis of d9-Tetrahydrocannabinol (THC) Using Pyroprobe

Significance of the Topic

The accurate measurement of d9-tetrahydrocannabinol (THC) is critical for regulatory compliance, quality control, and safety assessment within the cannabis and hemp industries. Federal regulations limit THC content in hemp-derived products to below 0.3%, so reliable analytical methods are essential to confirm product legality and ensure consumer protection.

Objectives and Study Overview

This application note describes the development and validation of a thermal extraction method using a Pyroprobe coupled to gas chromatography/mass spectrometry (GC/MS) for the quantification of THC. The main goal was to establish a robust protocol capable of precise and reproducible THC determination, evaluated through relative standard deviations (RSD) from multiple replicate analyses.

Methodology and Instrumentation

This study employed a two-component stock standard containing THC and methyl stearate as an internal standard (IS), each at 0.5 µg/µL. One-microliter aliquots were applied to Drop-In-Sample-Chamber (DISC) tubes and immediately analyzed to minimize analyte degradation. Thermal extraction was performed with a CDS Model 6200 Pyroprobe set at 300 °C for 30 minutes, followed by transfer to a GC/MS system. Key GC/MS conditions included:

• Column: 5% phenyl, 30 m × 0.25 mm
• Carrier gas: Helium at 1.25 mL/min, split ratio 75:1
• Injector temperature: 300 °C; transfer line: 350 °C
• Oven program: 80 °C hold for 10 min, ramp at 15 °C/min to 320 °C
• Mass range: m/z 35–600; ion source 250 °C

Base peaks at m/z 299.2 for THC and m/z 74 for the internal standard were monitored to calculate area ratios.

Main Results and Discussion

Seven replicate analyses yielded area ratios of IS to THC ranging from 5.01 to 5.54, resulting in an overall RSD of 3.4%. Total ion chromatograms demonstrated consistent peak shapes and retention times across all runs, confirming the method’s reproducibility and minimal thermal degradation of THC under the selected conditions.

Practical Benefits and Applications

The validated Pyroprobe–GC/MS method offers several advantages:

• Direct thermal extraction minimizes sample preparation and solvent use.
• High reproducibility (RSD ≤ 3.5 %) supports routine compliance testing.
• Rapid throughput through simple DISC tube loading and standardized pyrolysis parameters.

This approach can be applied to hemp and cannabis matrices for regulatory screening, quality assurance, and research investigations into cannabinoid content.

Future Trends and Potential Applications

Advancements may include integration with high-resolution mass spectrometry for improved specificity, automation of sample loading for higher throughput, and coupling with comprehensive two-dimensional GC to separate complex botanical matrices. Ongoing research into pyrolysis kinetics could further refine extraction temperatures and times for diverse sample types.

Conclusion

The thermal extraction method using the CDS Model 6200 Pyroprobe and GC/MS demonstrated reliable quantification of THC with an RSD of 3.4%. Its simplicity, accuracy, and reproducibility make it suitable for compliance testing of hemp-derived products and broader analytical applications in cannabis research.

References

1. Sam, K. Investigative Multi-Step and Quantitative Analysis of Cannabidiol Oil using the Pyroprobe; CDS Analytical App Note #201