Extraction
Dried cannabis material (bud, trim, or fan leaves, milled)-was obtained. 50 g plant matter was added to a 1.5 inch diameter aluminum column 12 inches in length, supported by a stand with a screen secured on the bottom and rubber stopper with a center hole containing a nozzle on the top. In a well ventilated area, two 300 mL cans of 10° C 99+% pure n-butane were poured into the top of the column, about 5-10 minutes. The extract was collected in a beaker and placed on dry ice in a cooler. The extraction was repeated two times and the extracts were combined prior to the separation step.
Separation
The beaker containing the extract was allowed to sit directly on dry ice in a Pelican ProGear Elite Marine Deluxe Coolers cooler for 4 hours at approximately -70° C. Precipitate was observed on the bottom of the beaker. The extract was filtered through a vacuum assisted Buchner funnel using 12.5 cm diameter 101 fast filter paper and coffee filter taking care not to disturb the cake on the bottom of the beaker. The filtrate was returned to a clean beaker and put back in the cooler on top of the dry ice for 3 hours and filtered again in a Buchner funnel with a coffee filter and slow quantitative filter. After two filterings, the solvent extracts were optically clear. The retentate turned brown upon the solvent evaporation, is believed to be lignin, lecithin, and/ or other undesirable, high molecular weight materials that were extracted by the solvent.
Crystallization
THCa, the acid precursor to THC, was crystallized out of solution using the filtered solvent extract. Glass beads were added to the beaker before putting it into an undisturbed deep freeze (-75° C.). Crystals formed in between 12 hours and several days. The crystals were harvested by filtering solvent and extract and capturing the retentate as well as removing crystals by scraping them from the glass beads through a sieve with a metal spatula. After collecting the crystals, the butane and extract mixture were returned to the deep freeze to collect additional crystals. Two morphologies of crystals were observed, “sheet” and “ball" crystals. The THCa crystals were 98+% pure THCa in quantities greater than 50% of the total extracted THCa. The balance of the THC and THCa remained in the solvent with the rest of the plant extract residual filtrate which is enriched in cannabinoids and terpenes relative to the original plant extract.
Patent
