A Novel Dissolved Oxygen Sensor Based On Ru(bpy)₃～(2+)/agar Gel Modified Electrode

Electrochemiluminescence method is one of the most interesting subjects in analytical chemistry field. This technique not only retains the advantage of the conventional chemiluminescence(CL) analysis, but also offers some advantages over more conventional CL. Firstly, the ECL reaction can be easily regulated and manipulated by the applied potential. Secondly, the ECL emission is concentrated close to the vicinity of the electrode, which can be shaped and accurately positioned in relation to the optical measurement system for maximum sensitivity. Thirdly, the analyte can be in-situ modified electrochemically to form the corresponding CL active specie without the chemical contamination due to the addition of the necessary reactants in the corresponding CL reactions. Thus, ECL analysis, compared to CL analysis, offered the more alternative potentials to regulate the ECL reaction for analytical purpose.Since the luminol-based ECL phenomena was firstly observed by Harvey in 1929, the ECL was paid much attention by the analysts, and a lots of analytes had been detected with ECL analytical technique during the 1980s and 1990s.This approach has many obvious advantages over other analytical methods, and it has been applied successfully to many fields, such as life science, clinical medicine, environment, immunoassays and DNA probe analysis etc. Nowadays, analysts are working on biological chip and exploiting ECL substance etc.The main contents of our study could be described as follows: Firstly, a novel dissolved oxygen sensor based on Ru (bpy)₃²⁺/agar gel modified electrode was developed. The sensor showed an ECL response to oxygen in organic solvent. The ECL intensity was linear with the concentrations of oxygen in toluene and xylene, respectively. The correlation coefficient was 0.995 with a RSD of 0.033 (n = 10) for toluene. The sensor possessed stability and precision for oxygen determination. We also discussed the ECL of Ru(bpy)₃²⁺/ agar in ethanol, butanol and dibutyl ester. The work provided a new way for immobilization Ru(bpy)₃²⁺ and the application of detection oxygen in organic solution.Secondly, we determinated of phenol by using electrochemiluminescent quenching of Ru(bpy)₃²⁺-C₂O₄^2- System. Phenol showed an ECL inhibiting signal in Ru(bpy)₃²⁺-C₂O₄^2-. The pH values of Ru (bpy)₃²⁺-C₂O₄^2- were studied. The mechanism of ECL inhibition had been proposed due to energy transfer from the excited state Ru(bpy)₃^2+* to a quinone or ketone or their polymer formed by electro-oxidation of phenol.