UV-Activated Luminescence/Colourimetric O₂ Indicator

Figure 2

UV/Vis spectra recorded for an indigotetrasulfonate (ITS) deoxygenated aqueous solution 2.8×10⁻⁵ mol dm⁻³, pH4): broken line. Upon reaction with a zinc amalgam pellet, the blue ITS solution is reduced to leuco-indigotetrasulfonate (leuco-ITS), signalled by the decrease in absorbance at 590 nm and the increase at 390 nm (spectra were recorded every 30 minutes). The insert diagram illustrates the excitation spectrum (solid line; 𝜆_em=485 nm) and emission spectrum broken line; 𝜆_ex=390 nm) of a 2.8×10⁻⁵ mol dm⁻³leuco-ITS deoxygenated aqueous solution, at pH4.