Tetrahydrocannabinol (THC)-modified screen-printed carbon electrodes (SPCEs): insights into stability

Stability of THCi-based sensors to detect ultra-low concentrations of THC by controlling the principal factors contributing to THC oxidation: temperature, humidity, airflow, and light, to extend the shelf-life and improve electrochemical signals. THC (Δ 9 -tetrahydrocannabinol) is the major psychoactive constituent of cannabis, accountable for instigating euphoric effects in individuals. With the imperative need for a roadside testing device for the detection of THC, this study aims to overcome the challenges associated with the stability of a biomolecule-free sensor capable of detecting ultra-low concentrations of THC. Since THC is highly susceptible to oxidation, this study explores different avenues to create optimal storage conditions to minimize the oxidation of THC prior to detection. Hence, all experiments were conducted by controlling the principal factors contributing to the oxidation of THC: temperature, humidity, airflow and light, to extend the shelf-life of the manufactured electrodes and engender stable electrochemical signals. It is concluded that frozen storage conditions and a second acidic pH modification were ideal for improving the stability of the modified electrodes from day one up to a period of six months.