Quality Control of CBD oils

Importance of the topic

Cannabidiol (CBD) oils have gained widespread acceptance in pharmaceutical, food and cosmetic applications due to their non‐psychoactive nature and reported health benefits. Ensuring accurate quantification of CBD and other cannabinoids is critical for product safety, label compliance and consistent therapeutic outcomes. Traditional HPLC methods, while accurate, are time‐consuming and require extensive sample preparation and skilled analysts. A rapid, cost‐effective alternative such as visible‐near infrared (Vis‐NIR) spectroscopy can transform quality control workflows and support real‐time monitoring in production environments.

Objectives and overview of the study

This study evaluates the capability of the Metrohm DS2500 Liquid Analyzer, operating in Vis‐NIR transmission mode, to quantify cannabinoid content in various CBD carrier oils. The primary goals were to develop a robust calibration model, compare results with a reference HPLC method and demonstrate the advantages of NIR analysis in terms of speed, simplicity and reproducibility.

Methodology and instrumentation

Seventeen samples covering three common carrier oils (hemp seed, fish oil and medium‐chain triglyceride oil) were prepared without additional sample treatment. Spectra were acquired at 40 °C using 8 mm path length disposable borosilicate vials to ensure uniform temperature and minimize cross‐contamination. Data acquisition and chemometric model development were performed with the Vision Air Complete software suite.

Used instrumentation

• DS2500 Liquid Analyzer (Metrohm #2.929.0010)
• DS2500 Holder for 8 mm vials (Metrohm #6.7492.020)
• Disposable borosilicate vials, 8 mm path (Metrohm #6.7402.000)
• Vision Air 2.0 Complete spectroscopy software (Metrohm #6.6072.208)

Main results and discussion

A prediction model built on all 17 Vis‐NIR spectra showed excellent agreement with the HPLC reference values. Key figures of merit included:

• Calibration coefficient of determination (R²): 0.959
• Standard error of calibration (SEC): 0.99 %
• Standard error of cross‐validation (SECV): 1.21 %

Correlation plots confirmed minimal bias across the concentration range. The DS2500 provided rapid measurements (<1 minute per sample) without the need for solvents or extensive operator training.

Benefits and practical applications

• High throughput: Single‐sample analysis in under one minute
• Non‐destructive: No chemical reagents or solvent disposal required
• Robust operation: Dust, moisture and vibration resistance enable use outside dedicated laboratories
• Streamlined workflow: Disposable vials eliminate cleaning steps and reduce cross‐contamination risk
• Regulatory compliance: Reliable quantification supports accurate labeling and quality assurance

Future trends and opportunities

• Integration with automated sample handling robots for high‐throughput production lines
• Expansion to inline or at‐line process monitoring for real‐time quality control
• Development of multi‐analyte models to quantify additional cannabinoids, terpenes and impurities simultaneously
• Application of advanced machine learning techniques to enhance predictive accuracy and transferability between instruments
• Portable NIR devices for onsite testing in remote or field settings

Conclusion

The Metrohm DS2500 Liquid Analyzer coupled with Vis‐NIR spectroscopy offers a fast, reliable and user‐friendly alternative to HPLC for determining cannabinoid content in CBD oils. Its high correlation with reference methods, combined with minimal sample preparation and rapid turnaround, makes it an ideal tool for routine quality control in both laboratory and production environments.