An Electrochemical Gas Sensor for Δ ⁹ -Tetrahydrocannabinol in Cannabis Smoke: A Novel Approach for Air Quality Monitoring in Legal Cannabis Consumption Areas

As cannabis legalization expands globally, detecting Δ⁹-tetrahydrocannabinol (Δ⁹-THC) in air has become crucial for public health monitoring. This research addresses a significant gap by developing the first electrochemical sensor for gas-phase Δ⁹-THC detection, effectively overcoming electrode fouling challenges commonly found in liquid-phase sensing. Our innovative approach employs a manganese dioxide-modified screen-printed graphene electrode (MnO₂/SPGE) with a poly(acrylic acid) membrane immobilized with Fast Blue B salt. This configuration creates a selective sensing interface that facilitates both accumulation and specific interaction with Δ⁹-THC molecules. The proposed sensor demonstrated excellent analytical performance with a linear detection range of 25-250 ppb (R² = 0.9905), a limit of detection of 4.5 ppb, and sensitivity of 0.06 μA/ppb. Interference studies revealed exceptional selectivity, with minimal signal variations (±5%) despite high concentration ratios of potential interferents commonly found in postcannabis smoking environments. The proposed sensor's practical applicability was validated through comparative analysis with HPLC and GC-MS, successfully detecting Δ⁹-THC in cannabis tobacco smoke while showing no response to non- Δ⁹-THC-containing cigarette samples. This low-cost, disposable sensor offers significant advantages in simplicity, portability, and accessibility compared to conventional gas chromatography-mass spectrometry techniques, making it suitable for field applications in air quality monitoring related to cannabis investigations.