Figure shows the time-course plot of the C365 response, recorded from testing of a series of cannabinoidcontaining e-cigarettes prepared in house. As expected, a clear increase in C365 magnitude for an e-cigarette containing 5 mg/mL THC is observed, with no similar change for an e-cigarette containing an equivalent concentration of CBD. It is worth noting that this is an extremely low concentration compared to the practical use of THC. Figure also shows that detection of low concentrations of THC (10%) in the presence of CBD is also possible with this approach. From Figure , we find that the most significant changes to C365 signal are apparent at between ~10 -30 s, with subsequent decay of the signal. We suggest the decay of the signal represents a subsequent photochemical degradation step to a non-emissive photoproduct. Clearly this kind of time-frame suits the type of rapid detection we envisage. Thus, to detect THC with the EDD, we employ a 10 s irritative step where the calculated ratio of C365 response preand post-irradiation must exceed a pre-defined threshold. Figure shows the validation of photochemical-based THC detection from a range of real-world THC extract vape pens, seized by the police.