Figure 7: A fluorescence turn-on solvatochromic sensor system.

(a) Schematic representation of a fluorogenic sensor system based on fluorescamine-amine adduct formation. (b) Photographs of vials containing solutions of fluorescamine (2 mg ml⁻¹) and amine (2 mg ml⁻¹) under 365 nm UV light. (c) Photographs of unprotected films (without PVP layer) under 365 nm UV light. (d) Photographs of PVP-protected films under 365 nm UV light. (e) Photographs of PVP-protected films under 365 nm UV light after exposure to various solvents.