Rapid Screening of Cannabinoids in Edibles by Thermal Desorption (TD) GC/MS & TD GC/FID

Importance of the Topic

The rapid growth of cannabis-infused food and beverage products demands analytical methods that deliver fast, reliable, and reproducible results. Screening techniques capable of minimal sample preparation and high throughput are critical for quality control, regulatory compliance, and consumer safety.

Objectives and Study Overview

This study evaluates Thermal Desorption–GC/MS and TD–GC/FID for rapid screening and quantitative analysis of key cannabinoids (THC, CBD, CBN) across diverse edible matrices: brownies, chocolate bars, tinctures, candies, beverages, gummies and cookies. The goal is to confirm label claims, assess precision, and compare direct desorption with solvent-based extraction workflows.

Applied Methodology and Instrumentation

• Instrumentation: Frontier Multi-Mode Pyrolyzer EGA/PY-3030D, Auto-Shot Sampler AS-1020E, Vent-Free GC/MS adapter, bench-top GC/MS and GC/FID.
• Evolved Gas Analysis (EGA) identified optimal thermal desorption zones for cannabinoids (typically 100–300 °C).
• Thermal Desorption Modes: Isothermal desorption at 300 °C or programmed ramp from 100 °C to 300 °C at 100 °C/min.
• Calibration Strategies: External Standard mixtures (CBD/THC/CBN) and Standard Addition approaches.
• Sample Preparation: Direct placement of milligram quantities in inert sample cups; thin-film deposition; IPA extractions for liquid or viscous samples.

Main Results and Discussion

• Chocolate Brownies: Triplicate TD-GC/MS analysis showed RSD 4.96% and THC concentration 0.996 mg/g, matching the 1 mg/g label.
• Chocolate Bars: RSD 7.18% and quantified THC 2.1 mg/g closely agreed with the stated 2 mg/g.
• Tinctures: Direct TD-GC/MS detected strong CBD signals. Isothermal and ramp programs produced equivalent profiles. IPA-based extraction quantified 89.1 mg CBD per 30 mL bottle (label 100 mg hemp extract).
• Candies: Direct TD and thin-film IPA methods yielded ~1 mg/g THC in agreement with labeling; IPA extraction reduced quantitative variability by improving homogeneity.
• Beverages: Separate top and bottom sampling revealed non-uniform THC distribution. Mixed solution analysis plus can rinsing recovered a total of 42.3 mg THC versus 45 mg label.
• Gummies & Cookies: TD-GC/FID achieved RSD <2% for CBD/THC; FID Effective Carbon Number similarity enabled accurate external standard quantitation. Label discrepancies (higher CBD detected) and minor cannabinoids (CBN, CBG) were identified.

Benefits and Practical Applications

• Solvent-free or minimal-solvent workflows reduce preparation time, solvent costs, and glassware use.
• Volatile-only TD retains non-volatiles in the cup, extending column life and system stability.
• Flexible thermal programs adapt to sample types and target analytes.
• MS and FID compatibility supports both structural identification and robust quantitation.
• Automation and high throughput suit routine QC and compliance laboratories.

Future Trends and Applications

• Coupling TD-GC with high-resolution MS for detailed profiling of minor cannabinoids and degradation products.
• Development of portable TD modules for on-site testing of edibles.
• Machine-learning spectral deconvolution for faster screening and improved library matching.
• Extension to profiling terpenes, flavonoids, and other bioactive compounds in cannabis products.

Conclusion

Thermal Desorption–GC-based workflows offer rapid, reproducible, and nearly solvent-free analysis of cannabinoids in complex edible matrices. EGA-guided TD-GC/MS and TD-GC/FID deliver consistent label confirmation and high throughput suited for modern QC and research laboratories.

References

• Suurkuush G. Validation of the Gas Chromatographic Method for THC, CBD and CBN Differentiation. University of Tartu, 2010.
• Poortman-van der Meer AJ, Huizer H. Improvement of Accuracy in THC Quantitation. Forensic Sci Int. 101(1999):1–8.
• Whitepaper: The Art and Science of Cannabis Beverages. Le Herbe: a 420 Venture Company, 2019.