Geographic origin determination of Brazilian Cannabis sativa L. (Marihuana) by multi-element concentration

The Marihuana Polygon production of Cannabis sativa L. supplies the northeastern region of Brazil and represents 30% of the nation's market. The international trend of indoor cultivation is also occurring in Brazil, and the Brazilian Federal Police (BFP) has been increasing its apprehension of cannabis seeds sent by mail. The present work aims to assess the utility of the multi-element composition of different cannabis plant parts and soil samples where the plants were cultivated to determine their geographic origin. Statistical tools were applied to classification of marijuana samples from distinct geographic regions within northeastern Brazil, including indoor cultivated samples. The multi-element quantification was determined using inductively-coupled plasma - optical emission spectrometry (ICP-OES), and the data were compared by the Kruskal-Wallis H test, and subsequently, multiple discriminant analysis (MDA). The results of the multi-element concentration of cannabis plant samples were also subjected to a principal component analysis (PCA) and an orthogonal partial least squares discriminant analysis (OPLS-DA). The cannabis plant samples from the Marihuana Polygon could be clearly separated from those cultivated indoors, and the distance between them was detectable. The MDA revealed that phosphorus, calcium, magnesium, selenium, and arsenic concentrations were used as variables for this separation. Our results demonstrate that multi-element composition analysis can be used to indicate the origin or cultivation location of cannabis plants. Routine laboratory analyses consisting of multi-element composition combined with statistical analyses provide a reliable tool by which C. sativa movement, cultivation, and interdiction efforts in Brazil may be assessed.

Keywords: Cannabis sativa L.; Geographic origin; Multi-element composition.