Università degli studi di Modena e Reggio Emilia

Two electrochemical sensors are proposed here for the first time for the fast screening of cannabinoids in Cannabis sativa L. plant material (inflorescences). The accurate control of cannabinoid content is important for discriminating between recreational, i.e. illegal, and fibre-type C. sativa samples, which differ mainly according to the amount of Δ9-tetrahydrocannabinol (Δ9-THC) and Δ9-tetrahydrocannabinolic acid (Δ9-THCA). Two screen printed electrodes obtained using different electrode materials were tested for the analysis of extracts from recreational and fibre-type C. sativa and their performance was compared with a consolidated method based on high-performance liquid chromatography (HPLC). The voltammetric responses recorded in the different samples reflected the compositional differences of the recreational and fibre-type extracts in accordance with the results of HPLC analyses. Moreover, the quantification of Δ9-THCA and the total cannabinoid content on the basis of the intensity of the peaks of the voltammograms was possible through a simple and fast electrochemical procedure.

Given the neuroprotective, anti-inflammatory, and analgesic properties of cannabidiol (CBD), many countries have recently legalized the use of fiber-type Cannabis products, including those known as 'Cannabis light'. Nonetheless, in freely commercialized products, it is not uncommon to find Δ9-tetrahydrocannabinol (THC), the principal psychoactive constituent of cannabis, in concentrations exceeding the legal limit. To determine whether a product is commercially viable, the THC/CBD ratio is typically analyzed using chromatographic techniques. However, chromatographic techniques have costs, complexity, and response times that prevent their in-situ use, making control actions much more expensive and ineffective. In this work, we report our preliminary activities aimed at verifying the possibility of performing in-situ analysis of cannabinoids in cannabis-derived products using an ad-hoc designed measuring system based on screen-printed electrodes modified with carbon black. The results obtained from preliminary tests comparing fiber cannabis (legal THC concentration) and recreational cannabis (illegal THC concentration) suggest that the proposed system can allow the effective and efficient in-situ analysis of cannabis-derived products.

The widespread diffusion of products deriving from Cannabis sativa L. led to the necessity of rapid and reliable methods for the identification of samples containing Δ9-tetrahydrocannabinol (THC), the psychoactive component of the plant, which imparts mental distortions and hallucinations. Although some efficient electrochemical sensors have been already proposed for such a purpose, they do not consider that the plant may also contain huge amounts of cannabidiol (CBD), which possesses an electroactive moiety quite similar to that of THC. The definition of both THC and CBD concentration is at the basis of discrimination between recreational-type and fibretype cannabis samples; detection of these species is not only important in vegetable samples but also in relevant commercial products and in biological fluids. We proposed here a screen-printed electrode coated with a layer of carbon black for the rapid identification of samples containing THC irrespectively of the simultaneous presence of CBD. The most performing carbon black typology used for such a purpose was chosen among various commercial products tested on the basis of preliminary tests performed on 1,3-dihydroxybenzene, constituting the redox active moiety of cannabinoids. The voltammetric responses collected in various solutions containing different amount of THC and CBD were initially elaborated by Principal Component Analysis, assessing the possibility of identifying samples with similar concentrations of THC irrespectively of the CBD concentration values, and vice-versa. Afterwards a preliminary Partial Last Square regression was performed to evaluate the possibility of a quantitative analysis of both THC and CBD. This approach suggests the possibility of using the sensor proposed to screen samples containing THC even in the presence of high amounts of CBD.