Facing the Forensic Challenge of Cannabis Regulation: A Methodology for the Differentiation between Hemp and Marijuana Samples / Presumptive and confirmatory methods for hemp and marijuana analysis

Abstract

Access to medical and recreational cannabis has been regulated in several countries. Cannabinoids are secondary metabolites used as chemical markers of Cannabis genus plants. Tetrahydrocannabinol (THC) and cannabidiol (CBD) are the most abundant cannabinoids and their proportion is used to differentiate hemp (THC/CBD<1) from marijuana (THC/CBD>1) varieties. Brazilian sanitary regulations permit prescription, importation and sale of cannabis-derived products by pharmaceuticals distributors and drugstores, even though their crops are still prohibited, and the current scenario is characterized by marijuana trafficking, legal trade of medical cannabis products, and cultivation and production of cannabis-derived products by patients and non-governmental organizations (NGOs), with or without judicial authorizations. Medical cannabis regulation is in progress and there is an urgent need to implement analytical methods for monitoring the chemical profile of cannabis crops. Thus, the goal of the present study was to propose a methodology based on presumptive and confirmatory methods to differentiate the two principal chemovars of Cannabis genus plants, i.e., CBD-rich (hemp) and THC-rich (marijuana). A color test and a validated high-performance liquid chromatography (HPLC) method were applied to six cannabis samples cultivated by patients with judicial authorization. The methodology proved to be useful for forensic purposes and for quality control of medical cannabis. Plants cultivated by patients showed three profiles, classified as THC-rich, CBD-rich and approximately 1:1 THC/CBD ratio.