“…Luminescent sensors composed of small molecules, [47][48][49] aptamers, [50][51][52][53][54][55][56] and nanomaterials, [57][58][59][60][61] developed for sensing and differentiating illicit drugs in solutions such as drinks 47,62 and biofluids. 48,55 In contrast, the development of luminescence-based detection of illicit drug vapours is still at an early stage for several reasons: (1) the low vapour pressures of most drugs, especially in salt form creates an issue of sensitivity; 12,13 (2) the difficulty of discriminating an illicit drug from potential interferants in the vapour phase gives rise to issues relating to selectivity; 8,63 and (3) the lack of understanding of the process behind the sensing response (turn-on, turn-off, colour change) of the luminescent materials (usually a film) when exposed to drug vapours, and the physical interactions between the drug and the sensing material. Given the potential of luminescence-based detection it is perhaps surprising that there are so few reports of it being used for the detection of illicit drugs.…”