Quick and Real-Time Potency Determination of Cannabinoids Using FTIR Spectroscopy

Importance of the Topic

Cannabinoid potency determines both therapeutic and psychoactive effects of cannabis products. Accurate, real-time measurement of key cannabinoids such as THC, THCA, CBD, and CBDA is essential for quality control, dosage recommendation, and regulatory compliance across a variety of matrices including concentrates, distillates, and infused products.

Objectives and Study Overview

This application note describes the development of a fast, reliable FTIR-based method to quantify THC, THCA, and total THC in cannabis concentrates and distillates. The study aims to replace or supplement traditional chromatographic assays with a spectroscopic approach that delivers results in seconds and supports routine laboratory workflows.

Methodology and Instrumentation

• Sample Types: Hydrocarbon and CO2 extracts including oils, waxes, budder, shatter, and purified distillates.
• Instrument: Agilent Cary 630 FTIR spectrometer equipped with a 1-bounce diamond ATR accessory.
• Spectral Acquisition: 4000–650 cm⁻¹ range, 128 scans at 8 cm⁻¹ resolution (~30 s per measurement), no sample preparation.
• Data Processing: Spectral preprocessing with mean centering and Savitzky-Golay first derivative smoothing; partial least squares (PLS-1) chemometric models built for each analyte.
• Method Automation: Calibration models integrated into MicroLab software to streamline analysis and reporting of multiple cannabinoids in a single run.

Main Results and Discussion

• Calibration Performance: R² values up to 0.99 for THC and total THC with RMSEP around 1 % for high-potency distillates (74–94 % THC) and below 1 % for trace THC in concentrates (1–6 %).
• Matrix Coverage: Separate PLS models for hydrocarbon and CO2 extracts; training sets included diverse concentrate forms to capture process variability.
• Correlation with Reference Methods: FTIR-predicted potency shows strong linear agreement with HPLC/GC reference data, enabling confident substitution in routine testing.

Benefits and Practical Applications

• Real-Time Analysis: Results available in seconds, enhancing production throughput and decision making.
• Nondestructive Testing: Preserves sample integrity for further analysis or sale.
• No Consumables: ATR technique requires no solvents or reagents, reducing operating costs.
• Compact and Portable: Small bench footprint supports in-line quality control and field testing.
• User-Guided Software: MicroLab streamlines method setup, calibration, and reporting, lowering training requirements.

Future Trends and Applications

• Extension to Plant Materials: Development of models for flower, trim, and other raw biomass.
• Additional Analytes: Calibration for CBD, CBDA, terpenes, and minor cannabinoids to broaden product profiling.
• Standardization Efforts: Harmonization of spectroscopic reference methods across jurisdictions to support regulatory compliance.
• Advanced Data Analytics: Integration of machine learning and cloud-based model sharing for continuous method improvement.
• On-Site and Portable Platforms: Expansion of handheld ATR-FTIR for field potency screening and remote compliance testing.

Conclusion

FTIR spectroscopy via the Agilent Cary 630 with diamond ATR provides a rapid, accurate, and cost-effective alternative to chromatographic assays for determining THC, THCA, and total THC in cannabis concentrates and distillates. The method’s high correlation with reference techniques, minimal sample preparation, and user-friendly software position it as a valuable tool for routine potency testing in both production and regulatory laboratories.

References

• Agilent Technologies, Inc. Application Note 5991-8810EN, June 2019.