Application of Chemometric Tools on Cannabis Samples Analyzed by the FTIR-ATR Method

Abstract

Marijuana is the most popular form of Cannabis sativa L. (Cannabaceae), popularly known, in Brazil, as the illicit drug. It is composed of the plant's aerial parts, such as the leaves and the inflorescences, which are dried, pressed and prepared as a mixture for smoking. Cannabis is the most consumed and illegally trafficked drug in the world, with an increasing number of users every year. The plant can be grown indoor and outdoor, and these differences may influence the drug's potency. In addition, marijuana can be mixed with diluents and/or adulterants such as aromatic plants, soil, commercial tobacco and feces that may contribute to cases of addiction and lead to serious health risks to its consumers. Studies involving the chemical profile of drug samples are important to provide evidence for trafficking, supporting the materiality of the crimes. The aim of this study is to analyze cannabis and marijuana seized samples by FTIR-ATR (range 1800-880 cm-1), combined with unsupervised chemometric tools, to differentiate the plant's cultivation forms and to suggest the use of diluents. PCA and HCA showed relevant trends of separation between seized 478 Brazilian Journal of Forensic Sciences, Medical Law and Bioethics 9(4):477-498 (2020) M. González et al. samples from indoor and outdoor cultivation. Additionally, differences between samples containing pure cannabis and samples including diluents were observed, grouping the samples by their chemical similarity. The use of FTIR-ATR, combined with chemometric tools, can generate fast and sensitive data, providing relevant information for chemical profiles of drug abuse.