For hundreds of years, cannabis has been one of the most known cultivated plants due to its variety of uses, which include as a psychoactive drug, as well as for medicinal activity. Although prohibiting cannabis products, the countries of the African continent are the largest producers of cannabis in the world; a fact that makes the trafficking of cannabis-based illicit drugs a high priority for local law enforcement authorities. The latter are exceedingly interested in the use of chemical analyses for facilitating quantification, identification, and tracing of the origin of seized cannabis samples. Targeting these goals, and focusing on the country of Ghana, the present study used inductively coupled plasma mass spectrometry (ICP-MS) for the determination of 12 elements (Pb, Cu, Ca, Mg, Mn, Zn, Cd, As, Hg, Fe, Na, and K) in cannabis seized by Ghana's law enforcement authorities and soils of cannabis farms. Furthermore, multivariate analysis was applied to distinguish among different cannabis farms and match them with the samples. As a result, 22 seized cannabis samples and 12 other cannabis samples with their respective soils were analyzed to reveal considerable As and Pb concentrations. As and Pb levels in cannabis were found up to 242 ppb for As and 854 ppb for Pb. Multivariate analysis was applied for separating different cannabis farms and seized samples based on elemental analysis, evidently linking the seized samples with two Ghana regions.
Keywords: ICP-MS; cannabis; forensic science; illicit drugs; soil; toxic metals.