Unprocessed cannabis extracts can contain over 100 cannabinoids, each with unique properties and medicinal uses. A variety of separation techniques can be used to obtain individual high-purity cannabinoids, however, achieving research grade purity required for pharmaceutical applications is most effectively performed via high performance liquid chromatography. While HPLC provides accurate results using microporous particles for packing, it is limited by its slow speed and high-pressure drop across the chromatographic column. However, if a supercritical fluid such as carbon dioxide (CO2) is used instead of traditional organic solvents, the process can be operated at higher flow rates due to the much lower viscosity of a supercritical fluid. Supercritical fluid extraction and chromatographic separation offer advantages in safety, process control, and purity for the rapidly growing cannabis industry. Precise system control and inherent safety of supercritical CO2 as a solvent offer numerous benefits over other extraction and purification methods: solvent property modulation with temperature and pressure, reduction of analysis time, the elimination of co-solvent and easy removal due to a CO2’s low boiling point, so additional purification is not required. The purpose of this study is to design and prototype a vertically integrated process offering efficient, cost-effective separation of research-grade cannabinoids. In this study, we assess supercritical fluid chromatography with pure CO2 as a novel method for the separation of cannabinoids. The separation performance was examined for a mixture of CBD, CBN, and THC using a pure CO2 mobile phase at 40°C with a custom made SFC system from CF Technologies. CFT equipment was operated using a silica column and pressures of 2000 psi to 10000 psi and modeled using an Aspen model to identify the ideal process conditions as a function of supercritical fluid flow rates, pressures and temperatures, and residence time of cannabis solids in order to achieve full separation.

Extraction and purification of research-grade cannabinoids with supercritical CO2

256th National Meeting (2018)

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