Analysis of Tetrahydrocannabinol Vape Oils Using Pyroprobe by Thermal Extraction

Significance of the Topic

Reliable identification and quantification of THC vape oils are essential for consumer safety, regulatory compliance, and differentiation between legitimate and counterfeit products. Direct thermal extraction offers a streamlined approach, minimizing sample preparation and reducing analytical variability.

Objectives and Overview

This study aimed to apply a multi-step thermal extraction method using a pyroprobe coupled with GC–MS to:

• Determine optimal extraction temperatures for THC and associated compounds.
• Compare chemical profiles of different commercial vape oil brands.
• Demonstrate the efficiency and accuracy of direct thermal extraction.

Methodology and Instrumentation

Sample preparation was eliminated by placing ~200 µg of vape oil into a DISC tube. The pyroprobe 6150 with autosampler performed sequential thermal ramps at 200 °C, 400 °C, and 600 °C, each held for 60 seconds. The pyroprobe was interfaced to a GC–MS system equipped with a 5% phenyl column. Key operating conditions included:

• Pyroprobe setpoints: 200 °C, 400 °C, 600 °C.
• DISC interface and transfer line: 300 °C.
• GC inlet: 360 °C, carrier gas helium at 1.25 mL/min, split ratio 80:1.
• Oven program: 40 °C (2 min), ramp at 12 °C/min to 300 °C.
• MS ion source: 250 °C.

Key Results and Discussion

The sequential extraction revealed:

• At 200 °C: selective vaporization of THC.
• At 400 °C: maximal release of THC, other cannabinoids, and carrier compounds—identified as the optimal temperature.
• At 600 °C: only trace amounts of cannabinoids and carriers.

Comparative analysis of two vape oils at 400 °C showed similar cannabinoid profiles but distinct carrier chemistries:

• Vape oil 1 contained polyethylene glycols (PEGs), which can generate toxic aldehydes upon heating.
• Vape oil 2 contained medium-chain triglycerides (MCTs), which pose a risk of lipid pneumonia upon chronic inhalation.

No vitamin E acetate was detected in either sample.

Benefits and Practical Applications

Direct thermal extraction with the pyroprobe offers:

• Elimination of laborious wet-chemistry sample preparation.
• Reduced risk of operator error and contamination.
• Rapid screening of THC and carriers in vape products.
• Potential for high-throughput quality control in regulatory and industrial labs.

Future Trends and Applications

Advances may include coupling thermal extraction with high-resolution mass spectrometry, expanding to other psychoactive or adulterant compounds, and developing portable platforms for on-site screening. Improved data analysis algorithms will further enhance compound identification in complex matrices.

Conclusion

This application note demonstrates that multi-step thermal extraction using a pyroprobe–GC–MS workflow effectively profiles THC vape oils without sample preparation. The optimized 400 °C extraction provides comprehensive information on active cannabinoids and carrier materials, facilitating efficient quality assessment and counterfeit detection.