The decomposition of acidic and neutral cannabinoids in organic solvents

Abstract

High‐pressure liquid chromatography was used to study (a) the relative efficiencies of methanol, chloroform, light petroleum (B.P. 40–60°) and methanol‐chloroform (9:1) for extracting neutral and acidic cannabinoids from cannabis resin; (b) the decomposition patterns of the resulting solutions under various storage conditions, and (c) the cannabinoid profile of a cross section through a block of cannabis resin. The results show that (a) methanol is the most effective extracting solvent of those tested; (b) acidic cannabinoids in solution decompose in darkness by varying amounts depending on the temperature, solvent, storage time and particular cannabinoid; (c) neutral cannabinoids in solution are relatively stable in darkness; (d) daylight causes appreciable decomposition of both acidic and neutral cannabinoids in solution, and (e) the cannabinoid profile of a resin is complex with lower levels of acidic material in the outer layers. 1977 Royal Pharmaceutical Society of Great Britain