Preliminary evaluation of the use of a disposable electrochemical sensor for selective identification of Δ9-tetrahydrocannabinol and cannabidiol by multivariate analysis

Abstract

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 fibre-type 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.