Solutions of pure cannabinoids, nine samples of herbal and two of resin cannabis (one freshly prepared) were stored in varying conditions for up to 2 years. Exposure to light (not direct sunlight) was shown to be the greatest single factos in loss of cannabinoids especially in solutions, which should therefore be protected from light during analytical and phytochemical operations. Previous claims that solutions in ethanol were stable have not been substantiated. The effect of temperature, up to 20 degrees, was insignificant but air oxidation did lead to significant losses. These could be reduced if care was taken to minimize damage to the glands which act as "well filled, well closed containers". Loss of tetrahydrocannabinol after exposure to light does not lead to an increase in cannabinol, but air oxidation in the dark does. It is concluded that carefully prepared herbal or resin cannabis or extracts are reasonably stable for 1 to 2 years if stored in the dark at room temperature.

Twelve varieties of Cannabis sativa were grown out-of-doors in southern England during 1971 to 1973. Results show that for certain varieties highly active herbal cannabis can be produced. A warm climate with abundant sunshine does not therefore seem to be essential for high THC content. This was supported by results of growing plants in a greenhouse in varying lighting conditions including a limited period in total darkness. Considerable within and between plant variation was found and the importance of defining the plant part used, the stage of growth and the size of the sample is emphasized for comparative work involving quantitative results. Comparison of the present results with those for the same cannabis varieties grown in different parts of the world shows that all exhibit the same qualitative picture, that is, either THC-rich or CBD-rich. Since this chemical composition seems independent of environmental conditions it is inappropriate to refer to the two types as phenotypes; it is more likely that they represent two chemical races within the species Cannabis sativa L.

A convenient method for the complete extraction of the cannabinoids from fresh plant material, herbal cannabis, cannabis resin and reefers, has been devised. Chloroform was a more suitable solvent than light petroleum or ethanol and simple shaking of powdered material with the solvent was effective. Fresh material should be air‐dried and powdered before extraction. The main cannabinoids in the extract are determined by g.l.c. using androst‐4‐ene‐3,17‐dione as internal standard. The coefficient of variation for repeated determinations of THC on a single extract was 1.4%; for all operations, including sampling and extraction, it was 2.7%. Duplicate analyses of 24 samples of herbal cannabis and of 20 reefers, all of varying potency, showed that the errors fell within the expected limits for THC, CBD and CBN. The method is simple and rapid; duplicate determinations can be completed in about 2 1/2 h.

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