PVB-Bipyridylruthenium(II) Oxygen Sensor for the Determination of Trace Amount of Dissolved Oxygen in Non-aqueous Solvents with Spectrofluorimetry

A sensitive flow injection spectrofluorimetric analysis method was developed for the determination of trace amount of dissolved oxygen in non-aqueous solvents.A new prepared oxygen-sensitive film with polyvinyl butyral(PVB) was used as precursor and tris(2,2′-bipyridyl)ruthenium(Ⅱ) dichloride hexahydrate[Ru(bpy)3]Cl2·6H2O] as fluorescence indicator.The oxygen-sensitive film preparation parameters and the oxygen determination conditions were thoroughly studied.The results indicated that the prepared oxygen-sensitive film with thickness of about 0.5 mm showed the highest sensitivity to oxygen when it was prepared by 2.5 mL 1 mmol/L [Ru(bpy)3]Cl2·6H2O solution as precursor at 20 ℃ for 24 h and then dried at 40 ℃ for 48 h.The optimum determination conditions were as follows:excite wavelength:465 nm;flow rate:1.0 mL/min;temperature:25 ℃.Under the optimal conditions,the response time of the prepared oxygen-sensitive film to oxygen was less than 30 s and the relative standard deviations(RSDs) of fluorescence intensity were 2.4% and 4.4% for nitrogen saturated solution and oxygen saturated solution,respectively.The oxygen-sensitive film has excellent reversibility to dissolved oxygen,and could keep stable at least 120 d.The proposed method was applied to determine the concentration of dissolved oxygen in propylene glycol and PEG-400.The experimental results showed that the linearity of the Stern-Volmer plots were 0-69.12 mg/L for propylene glycol and 0-109.54 mg/L for PEG-400.Their detection limits were 4.25 mg/L and 0.56 mg/L,with RSDs(n=6) of 2.0% and 1.8%,respectively.