Oxygen-sensitive reverse-phase optode membrane using silica gel-adsorbed ruthenium(II) complex embedded in gelatin film Original Research Article

An oxygen-sensitive reverse-phase optode membrane consisting of tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) ditetrakis(4-chlorophenyl)borate adsorbed on silica gel and embedded in a gelatin film has been successfully fabricated and used to continuously monitor dissolved oxygen in organic solvents. The optode membrane shows a very strong and stable pink emission when excited by blue light and it is efficiently quenched by molecular oxygen. The response of the sensor displays typical nonlinear Stern–Volmer behaviour when the dissolved oxygen concentration in organic solvents is at high levels. But the sensor is most sensitive at lower oxygen levels and is linear in the range 0–1.14, 0–2.10 and 0–0.53 mM for dissolved oxygen in acetone, dimethyl formamide and toluene, respectively. The t95 response times of the sensor are 10 s on going from nitrogen-saturated toluene to air-saturated toluene and 22 s on going from air-saturated toluene to nitrogen-saturated toluene. The sensor has good reproducibility, high photostability, no hysteresis, good precision and long lifetime.