The Potency Determination of 16 Cannabinoids by UHPLC with Diode-Array Detection

Significance of the Topic

Cannabis legalization has driven the need for rapid and reliable potency testing of cannabinoids in products to ensure regulatory compliance, consumer safety, and consistent quality control.

Objectives and Study Overview

This study presents an optimized isocratic ultra-high-performance liquid chromatography method coupled with diode-array detection (UHPLC-DAD) for the simultaneous quantitation of 16 major cannabinoids. The goal was to achieve complete separation, a wide calibration range, and minimal analysis time.

Methodology and Instrumentation

The method was implemented on a Shimadzu Nexera-i (LC-2040C 3D) UHPLC system equipped with a photodiode array detector. Key parameters included:

• Column: Shimadzu NexLeaf CBX II, 1.8 µm, 3.0 × 100 mm with matching guard column
• Mobile phase: isocratic 25/75 water (5 mM ammonium formate, 0.1% formic acid) and acetonitrile (0.1% formic acid)
• Flow rate: 1 mL/min; column temperature: 30 °C
• Detection wavelength: 228 nm as a compromise for acidic and neutral cannabinoids
• Calibration: six-point curves (0.5–100 ppm) with 1/c weighting

Results and Discussion

All 16 cannabinoids were resolved within a 4.5-minute run with resolution values above 1.0. Calibration curves exhibited linearity (r2 > 0.999) across the full concentration range. Accuracy ranged from 96.4% to 100.8% and precision (RSD) remained below 3% at low (2.5 ppm), mid (25 ppm), and high (75 ppm) levels. Carryover assessments indicated negligible residual peaks after solvent blanks, with only a minor CBDVA signal on the first blank injection. Regular column washes are recommended to sustain performance.

Benefits and Practical Application

The proposed UHPLC-DAD method offers high throughput, robust quantitation, and simplified operation, making it suitable for routine potency analysis in quality assurance and regulatory laboratories.

Future Trends and Applications

Advancements may include coupling with mass spectrometry for enhanced specificity, exploring supercritical fluid chromatography for greener separations, validating in complex matrices (edibles, oils), and integrating automated sample prep for even greater throughput.

Conclusion

An isocratic UHPLC-DAD approach was successfully validated for the rapid and accurate determination of 16 cannabinoids. The balance of speed, sensitivity, and resolution positions this method as an effective tool for routine cannabis potency testing.

References

• Wang M. et al. Decarboxylation study of acidic cannabinoids using ultra-high-performance supercritical fluid chromatography/photodiode array-mass spectrometry. Cannabis and Cannabinoid Research. 2016;1(1):262-271.
• ElSohly M, Gul W. Constituents of Cannabis sativa. In: Handbook of Cannabis. 2014.
• Restek. 16 Cannabinoids on Raptor ARC-18 1.8 µm by LC-UV. 2017.