Ethanol extraction

Ethanol extraction uses ethyl alcohol (C₂H₅OH) to dissolve cannabinoids and terpenes from cannabis biomass. Ethanol is amphipathic — its polar hydroxyl group and nonpolar ethyl tail both engage with plant compounds — and selectivity is dominated by temperature. Cold (cryogenic) ethanol runs -20°C to -80°C (industry standard -40°C), is more selective, leaves chlorophyll and waxes and lipids in the biomass, and preserves terpenes and acidic cannabinoids. Warm or room-temperature ethanol runs 20–78°C, delivers higher yield, but pulls chlorophyll and waxes — requiring downstream winterization, filtration, and carbon, silica, or bleaching-clay polishing. Biomass-to-solvent ratios run 1:5 to 1:15 w/w. Contact times vary by technique: QWET (Quick Wash Ethanol) and cold quick-wash methods run 3–5 minutes; industrial cold soaks run 5–30 minutes; centrifuge-assisted (CUP-style) systems use cold ethanol in a centrifugal basket for rapid contact and phase separation. Solvent recovery is performed by falling-film evaporators (FFE), rising-film evaporators, or rotovaps at low temperature under vacuum. Published yield at cold ethanol -40°C, 1:15 ratio, 10 minutes is approximately 18–20 g per 100 g dry biomass (Nahar et al., PMC9786071). Crude ethanol oil runs 50–75% cannabinoids and refines to 85–95% distillate in downstream distillation. Historically, Tincture of Cannabis was listed in the U.S. Pharmacopoeia from 1850 to 1942; modern industrial cold-ethanol extraction scaled rapidly during the 2017–2020 U.S. hemp and CBD boom, becoming the dominant crude-production method feeding the distillate and vape-cart supply chain. Synonyms include QWET, QWISO (Quick Wash Isopropanol, topical-grade only — not food-safe), cryo-ethanol, and Golden Dragon. Regulatory limits run 5,000 ppm oral per USP <467> and most state programs, with California imposing 1,000 ppm inhaled and 5,000 ppm ingested; the FDA classifies ethanol as Class 3, and food-grade non-denatured ethanol is required for all consumables. Facility classification is typically C1D2, and ASTM D37.04 WK60435 applies. → See also: Distillate, FECO, RSO, CO2 extraction, Extract