Highly-sensitive detection of CP-type synthetic cannabinoids from e-cigarettes by a novel Zn/Bi bimetallic organic...

Synthetic cannabinoids (SCs), often masqueraded in "e-cigarettes," are novel popular psychoactive substances with diverse structures and complex material compositions, making their detection more challenging for prompt intervention. Herein, a novel electrochemical sensing platform based on Zn/Bi bimetallic organic framework-derived ZnO-Bi₂O₃ heterojunctions was constructed for the detection of cyclohexanylphenol synthetic cannabinoids (CP-type SCs: CP47,497 and CP55,940). The sensing characteristics of ZnO-Bi₂O₃ were studied under various conditions, including solvent composition, molar ratio of metal, and calcination temperature. The optimized ZnO-Bi₂O₃ heterojunction exhibited a larger surface area, more active sites, and stronger stability, conducive to enhanced electrochemical catalytic performance. Under optimal conditions, a ZnO-Bi₂O₃ modified screen-printed electrode (ZnO-Bi₂O₃/SPE) showed good linear responses toward CP47,497 and CP55,940 within the concentration ranges 7 × 10^-9 ~ 5 × 10^-6 M and 1 × 10^-9 ~ 5 × 10^-6 M, with detection limits of 2.3 × 10^-9 M and 3.3 × 10^-10 M, respectively. The sensor also depicted excellent reliability and can be used for on-site electrochemical detection of target objects in e-cigarettes with high recovery. Finally, the electrochemical oxidation mechanisms of CP47,497 and CP55,940 were studied for the first time, and electrochemical fingerprints of CP-type SCs were speculated.