Two-step CBG purification – combined matrix removal and peak recycling

Importance of the topic

The ongoing legalization of cannabis underscores the need for efficient purification of its bioactive constituents. Cannabigerol (CBG), known as the “mother of cannabinoids,” exhibits diverse therapeutic effects, but its separation is complicated by complex plant matrices and similarity to cannabidiol (CBD).

Objectives and overview

This work introduces a two-step purification strategy that integrates matrix removal and recycling chromatography. The goals were to eliminate non-target extract components and to resolve CBG from CBD with high purity and yield.

Used instrumentation

• High-pressure pump AZURA P 6.1L HPG (50 ml ceramic head)
• PurityChrom® 6 chromatography control software
• Dual UV detectors (3 mm flow cells, 2 µl volume)
• Multiport valves for sample injection, peak trapping, recycle and column switching
• Eurospher II C18 columns (250×8 mm, 10 µm particle size)
• PEEK capillaries (0.5 mm ID) and fraction collector for 1/16" tubing

Methodology

Dried hemp biomass was decarboxylated at 140 °C and extracted with ethanol. Following winterization at −20 °C and solvent removal, the extract was adjusted to 10 mg/ml in ethanol. Chromatographic separation used isocratic EtOH/H₂O (90:10, v/v) at 4 ml/min with UV detection at 228 nm. An upgraded recycling system employed a peak trap valve to park the CBG/CBD combined peak and a recycle valve to recirculate it between two columns, effectively simulating an extended column bed.

Main results and discussion

Analytical runs confirmed CBG and CBD coelution at 2.6 min. In step 1, peak parking diverted early and late eluting impurities. Step 2 applied repeated recycling cycles, achieving a clear separation pattern across fractions. Pooling fractions 1–7 yielded 100% pure CBG with 98% recovery, while extending to fraction 1–10 increased recovery to >99% at 91% purity. Later fractions exclusively contained CBD at up to 100% purity, demonstrating a trade-off between yield and purity.

Benefits and practical applications

The combined approach significantly simplifies cannabinoid purification by unifying matrix cleanup and enhanced resolution in one automated system. It offers scalable, reproducible isolation of high-purity CBG and CBD for pharmaceutical, nutraceutical, and research laboratories.

Future trends and potential applications

Future efforts may focus on full automation of valve actuation, adaptation to other minor cannabinoids and complex botanical extracts, coupling with mass spectrometry for real-time monitoring, scale-up for industrial throughput, and exploration of sustainable solvents to minimize environmental impact.

Conclusion

The implemented two-step recycling chromatography system effectively removes matrix interferences and resolves closely eluting cannabinoids. Peak parking and recycling achieve up to 100% CBG purity, offering a versatile platform for advanced phytochemical separations.

References

• Compagnin G., Krauke Y., Felletti S., Greco G., Buratti A., Cavazzini A., Catani M., “Green cannabigerol purification through simulated moving bed chromatography,” Green Analytical Chemistry, Article 100066 (2023).
• Nachnani R., Raup-Konsavage W.M., Vrana K.E., “The pharmacological case for cannabigerol,” Journal of Pharmacology and Experimental Therapeutics, 376(2):204–212 (2020).
• Compagnin G., Krauke Y., Felletti S., Greco G., “Improved recycling chromatography – how to make faster and automatic separations of peak pairs,” KNAUER, 2023.
• Loxterkamp L., Monks K., “Cannalyze: determination of 16 cannabinoids inside flowers, oils and seeds,” KNAUER, 2020.