Romano LL, Arno Hazekamp A (2013) Cannabis Oil: chemical evaluation of an upcoming cannabis-based medicine. Cannabinoids 2013;1(1):1-11
This is a 2013 report of the perfect European combination of cannabis and olive oil. Luigi L Romano is from Department of Pharmacy, University of Siena, Italy. Arno Hazekamp is from Plant Metabolomics group, Institute of Biology, Leiden University, The Netherlands. Together they compared the extraction of cannabinoids and terpenes of commonly used solvents and olive oil.
- Naphtha (light hydro treated petroleum distillate; Coleman® fuel)
- ethanol, pure
- Petroleum ether (boiling point 40-65°C; analytical grade)
- Extra virgin olive oil and water
- olive oil alone
Traditional solvents method
five grams of flower was mixed with 100mL solvent, agitated for 5 min, and filtered with filter paper. The extracted flower was mixed with another 100 mL of solvent and the process was repeated. The extracts were combined and evaporated under a stream of nitrogen gas. The residues were reconstituted in 100mL 100% ethanol. An addition charcoal filter step was added to the EtOH method to remove the chlorophyll but was found to remove terpenes as well.
Olive oil and water method
Cannabis, 5g was mixed with 20mL olive oil and 50 mL water. This mixture was heated in a water bath at ~98°C for 60 min. The oil was separated from the cannabis using a French coffee press. The plant material was rinsed with 20 mL water and separated with a French coffee press. The extracts were combined and placed in a freezer at -20°C overnight. The water portion froze. The olive oil on the top layer was poured off. Note that this extract is theoretically 5x as concentrated as the traditional solvents… before the evaporation step.
Olive oil only method
In the olive oil only method 10g of cannabis was heated at ~98°C with 100 mL olive oil for 120 min. After cooling the extract was filtered through a French coffee press.
What is a French coffee press?
The French coffee press is basically a cylindrical shaped carafe with plunger with some filters attached to the end.
The ideal press for cannabis will have filters that keep small particles of flowers from getting into the extract and filters that are easy to remove and clean.
Quantitation of cannabinoids and terpenes
Extracts were analyzed by gas chromatography and flame ionization detection. High pressure Liquid Chromatography (HPLC) was used to resolve THC from THCA.
Neither Method resulted in the complete conversion of THCA to THC. It is interesting to note that the two oil methods had greater conversion than ethanol and pet-etherbut not Naphtha.
Terpinoline, phellandrene, and terpineol have menthol like structures. Myrcene and ocimnene have a linear structure like the original geranyl pyrophosphate without the ring formation.
Note that α-caryophyllene and humulene are different foldings of the same molecule presented on the terpene page. are β -caryophyllene is another complex terpene. Cadinene is related to the menthol family with an added ring. Elemene is also a vaguely menthol like compound.
It would appear that these extractions were performed once, hence no error bars. It should be noted that the traditional solvents leave open the option of further concentration. The authors briefly eluded to extraction of chlorophyll as an undesirable consequence of extracting terpenes and cannabinoids. The olive only method appears to be best in this limited study. This method has the lowest ability to concentrate the cannabinoids and terpenes. The oil and water are interesting. The near boiling water may suspend or dissolve many terpenes that are only slightly soluble in water. Freezing the oil/water mix has the effect of forcing solutes into the oil layer. Shaking the cold mixture might facilitate this partitioning.