Figure shows the spectra acquired after artificial actuation of, PG:VG-only, MDMB-4en-PINACA and MDBM-CHMICA containing e-cigarettes. Fluorescence emission of both indazole-and indole-based SCs is resolved on-filter when present in PG:VG e-liquid at 1.5 mg/mL, with a 𝜆 𝐸𝑚 𝑚𝑎𝑥 of ~350 nm. No fluorescence emission is detectable from actuation of an e-cigarette containing PG:VG only. These data indicate that we can detect SCs present in e-liquid at concentrations represented in the low range of real-world samples.