Quantitation of Cannabinoids in Cannabis Dried Plant Materials, Concentrates and Oils based on AOAC Official Method 2018.11 Part I: PDA Analysis

Importance of the Topic

Accurate measurement of cannabinoid content is essential for ensuring product quality, regulatory compliance and consumer safety in the expanding cannabis industry.

Objectives and Study Overview

This work adapts the AOAC Official Method 2018.11 for quantitative analysis of twelve major cannabinoids to the Shimadzu Nexera X3 LC-40 series with PDA detection, validating its performance for dried plant materials and related hemp products.

Methodology and Instrumentation

The analysis was conducted on a Shimadzu LC-40 X3 system comprising a binary pump LC-40BX3 with eluent degasser, autosampler SIL-40X3, column oven CTO-40C and PDA detector SPD-M40 with an UHPLC flow cell. A Shim-pack Velox C18 column (150×2.1 mm, 1.8 µm) was used with a gradient elution of 20 mM ammonium bicarbonate (pH 3.2) and acetonitrile at 0.4 mL/min and 25 C. Injection volume was 3 µL with PDA acquisition at 240 nm (10 nm bandwidth) and reference at 360 nm. Standard mixtures of twelve cannabinoids were prepared at five levels between 0.5 and 10 mg/L. Sample preparation of four hemp tea products followed a liquid extraction protocol aligned with the official method.

Main Results and Discussion

• Baseline separation of all twelve cannabinoids met USP resolution criteria for critical pairs (CBG/CBD >1.3, d9-THC/d8-THC >1.7).
• Calibration curves displayed high linearity with determination coefficients above 0.999 across the tested concentration range.
• A PDA sampling rate of 3.125 Hz provided a balance between sensitivity and alignment with the original AOAC requirement of 2.5 Hz.
• Quantitation of four commercial hemp tea samples revealed total CBD content from 0.51 to 1.76 percent (5.09 to 17.63 mg/g) with negligible psychoactive THC after decarboxylation correction.

Benefits and Practical Applications

• The validated method on a cost-effective Shimadzu platform supports routine quality control in cannabis testing laboratories.
• High resolution and sensitivity ensure reliable detection and quantitation across diverse sample matrices.
• Compliance with an official AOAC protocol enhances regulatory acceptance and interlaboratory consistency.

Future Trends and Possibilities

• Integration of high-resolution mass spectrometry to improve selectivity and detection of minor cannabinoids.
• Automation and high-throughput workflows for large-scale sample screening.
• Extension of the method to complex matrices including edibles and concentrates.
• Development of portable chromatographic systems for on-site testing.

Conclusion

The study demonstrates that AOAC Official Method 2018.11 can be seamlessly implemented on the Shimadzu Nexera X3 LC-40 series with PDA detection, delivering reliable separation, quantitation and compliance with regulatory standards for cannabinoid analysis.

References

1. AOAC INTERNATIONAL. About AOAC INTERNATIONAL. 2021.
2. Vaclavik L et al. Quantitation of Cannabinoids in Cannabis Dried Plant Materials, Concentrates, and Oils Using Liquid Chromatography–Diode Array Detection Technique with Optional Mass Spectrometric Detection Single-Laboratory Validation Study First Action 2018.11. Journal of AOAC International 102(6):1822–1833. 2019.