Extraction of medicinal cannabinoids through supercritical carbon dioxide technologies: A review

The pharmaceutical importance of cannabis is growing due to the natural non-psychoactive and psychoactive cannabinoids. For medicinal and forensic purposes, the effective extraction and quantification are essential to fully utilise the natural cannabinoids. The supercritical fluid extraction (SFE) process has gained increasing interest due to its selective extraction, short processing time (partly due to the efficient solvent removal process - supercritical fluid to vapour - leaving a solvent free product), low running cost, and low impact on the environment, compared to that of most conventional extraction methods. In this review, the extraction of cannabinoids through SFE methods have been summarised. The advantages of SFE of cannabinoids over conventional extraction procedures; such as microwave-assisted extraction, solid phase microextraction, hard-cap espresso, soxhlet extraction, high-throughput homogenization, ultrasound-assisted extraction, vacuum distillation of lipid-based extract, and liquid-liquid extraction are discussed. Furthermore, this review examines the importance of the SFE of cannabinoids by coupling with various conventional extraction methods, separation techniques, selection of a suitable co-solvent/modifier, and appropriate sample preparation. Additionally, the applications of using SFE technology and cannabinoids are reviewed with a focus on industrial, pharmaceutical, waste by-products, and purification.