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

Significance of the Topic

Cannabinoid potency analysis is critical for dosing recommendations and quality control of cannabis products. Rapid and accurate measurement of THC, THCA, and total THC ensures compliance with regulatory standards and optimizes product formulation. Traditional chromatographic methods offer high accuracy but are time-consuming and resource-intensive. Fourier transform infrared (FTIR) spectroscopy presents a fast, cost-effective, and nondestructive alternative for real-time potency assessment.

Objectives and Study Overview

This study evaluates the performance of the Agilent Cary 630 FTIR spectrometer with a diamond ATR accessory for quantifying cannabinoids in concentrates and distillates. It aims to develop multivariate calibration models correlating FTIR spectral data to reference HPLC/GC potency values, enabling immediate potency predictions for THC, THCA, and total THC in under 30 seconds per sample.

Methodology

1. Sample Preparation: Concentrates (oils, waxes, budder, shatter, sugars) and distillates were measured directly without any pretreatment.
2. Instrumentation: Agilent Cary 630 compact FTIR with 1-bounce diamond ATR accessory; spectral range 4000–650 cm–1; 128 scans at 8 cm–1 resolution (~30 s per spectrum).
3. Data Acquisition: ATR spectra acquired using MicroLab software; sensor cleaned between samples with acetone or ethanol.
4. Calibration Development: Partial least squares (PLS-1) regression models built separately for THC, THCA, and total THC. Spectral preprocessing included mean-centering and Savitzky–Golay first derivative with nine-point smoothing. Models covered variations in extraction solvents (hydrocarbon, CO2) and concentration ranges.

Used Instrumentation

• Agilent Cary 630 FTIR spectrometer
• 1-bounce diamond ATR sampling accessory
• MicroLab PC software for data acquisition and method deployment

Main Results and Discussion

The PLS-1 models demonstrated strong correlations between FTIR-predicted and reference potency values:

• Distillates (Total THC 74–94%): R² = 0.99; RMSEP ≈ 1%
• Concentrates (Total THC 68–87%): R² = 0.95; RMSEP ≈ 6%
• Concentrates (THCA 63–83%): R² = 0.95; RMSEP ≈ 6%
• Concentrates (THC 1–6%): R² = 0.99; RMSEP ≈ 0.8%
• Concentrates with CO₂ extraction (Total THC 36–66%): R² = 0.94; RMSEP ≈ 5%

These results confirm that FTIR spectroscopy combined with chemometric analysis provides reliable, laboratory-grade potency measurements that align closely with HPLC/GC references.

Benefits and Practical Applications

• Real-time potency determination in seconds
• Nondestructive analysis; no sample consumption
• No consumables or solvents required
• Compact, portable instrument ideal for laboratory and field settings
• High sample throughput facilitates process control and productivity
• Method-driven software simplifies user workflow

Future Trends and Possibilities

• Extension to flower, trim, and other dried plant materials
• Development of calibration models for CBD, CBDA, and minor cannabinoids
• Adaptation to diverse extraction matrices and infused products
• Standardization of FTIR-based potency methods across jurisdictions
• Integration with production lines for inline monitoring

Conclusion

The Agilent Cary 630 FTIR spectrometer, coupled with multivariate calibration, enables rapid, accurate, and nondestructive potency analysis of cannabis concentrates and distillates. This approach significantly reduces analysis time and operational costs compared to traditional chromatographic techniques, supporting efficient quality control in the cannabis industry.

References

• Agilent Technologies, Inc. Application Note: Quick and Real-Time Potency Determination of Cannabinoids Using FTIR Spectroscopy (5991-8810EN), 2019.