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The percentage rate of change into cannabinoids (Cannabidiol [CBD], tetrahydrocannabinol [THC] and cannabinol [CBN]) was higher in cannabis samples than in the extracts. This is probalby due to the decomposition of acids into corresponding neutral cannabinoids under the conditions of storage. Previous claims that CBD content in plant material is relatively constant are not substantiated by our results. There was a 1.0-2.5-fold increase in CBD content in plant material compared with the extracts. However, the fact that there was no appreciable increase in CBD/CBN content in the stored extracts of the same samples supports the view that the step-wise extraction does not bring the acids into the final extract pure delta 9THC decomposed at a rate of 41 per cent per year under tropical storage conditions. The delta 9THC content decreased in the samples and equally in the extracts though 100 per cent conversion of THC to CBN does not take place. The higher CBN content found in extracts than that expected by the conversion THC to CBN is a result of metabolic conversion.

A method has been evolved for assigning the source of supply or origin of illicit heroin samples. The content of morphine, codeine and acetyl products and the ratios of morphine to codeine and heroin to acetylcodeine obtained from opium samples of known origin as well as the content of heroin (diacetylmorphine) and acetylcodeine and their ratios in illicit heroin samples that have been found to belong to the same source of supply as the known opium samples are used as the basic criteria for a comparison to determine the origin of illicit heroin samples. Because the content of alkaloids in opium and heroin samples varies considerably, the number of opium and illicit heroin samples of known origin analysed should be sufficient to determine a representative composition of alkaloids in such samples for a given geographical area and period of production. It was observed that the theoretical ratio of heroin to acetylcodeine increases two-fold at each stage of the chemical conversion in the series opium-morphine-heroin. The ratios of heroin to acetylcodeine obtained from opium samples of known origin showed significant variation, which enabled the author to make distinct composition profiles of the alkaloids for each geographical area studied. Such profiles made it possible to compare heroin samples of known origin with illicit heroin samples of unknown origin and to determine the geographical area from which the latter originated. This method can also be applied in determining the origin of illicit morphine samples.