Determination Of H₂O₂ Using H₂O₂ Sensor Based On Room-temperature Phosphorescence And Electrochemiluminescence Based On Solid-state [Ru(dpp)₃][(4-Clph)₄B]₂

Hydrogen peroxide is an important trace gas that plays a significant role in the troposphere. In addition, hydrogen peroxide is also widely used in industrial process. The excess of hydrogen peroxide are hazardous, so, a sensitive and reliable detection method for hydrogen peroxide is of great importance in clinical, food, pharmaceutical and environmental fields.In recent years, a great number of methods for H2O2 determination have been reported, including titrimetric, spectrophotometric, fluorescence, electrochemical, chemiluminescence, and chromatographic methods However, H2O2 sensor based on room-temperature phosphorescence is seldom reported. In this study, the phosphorescence material of nano TiO2/SiO₂ composite oxides which produces highly emissive broadband phosphorescence from 450 nm to 650 nm at an excitation wavelength of 403 nm was synthesized with sol-gel method, and it exhibited a remarkable selective phosphorescence quench toward hydrogen peroxide in the presence of common ions, acids, and bases in aqueous solution. So, we fabricate H₂O₂ sensor using nano TiO2/SiO₂ composite oxides as sensitive material.In the presence of H₂O₂, the phosphorescence intensity of the H₂O₂ sensor is reduced gradually as H₂O₂ concentration increased. There are linear relationships between phosphorescence intensity and H₂O₂ concentration ranging from 7.0×10-7 to 7.0×10-2 mol/L. Moreover, the phosphorescence of the H₂O₂ sensor can be recovered in strong reducing agents, such as hydroxylamine hydrochloride solution and also exhibit good linear response in H₂O₂ concentration going from 7.0×10-6 to 7.0×10-2 mol/L of successive determination.We studied the mechanism of the change of the H₂O₂ sensor based on room- temperature phosphorescence of TiO2/SiO₂ composite after adding H₂O₂. It suggested that the reason of disappearance of the phosphorescence after adding H₂O₂ is owe to formation of stability of O-O moieties on Ti(IV) species. We also studied the conditions and mechanism of phosphorescence recovery. The phosphorescence recovery of the composite is owe to the strong reducibility of hydroxylamine hydrochloride, which can destroy the O-O bond and make it reduction.The determination of H₂O₂ is of great importance in enzyme reaction. We can determine the concentration of glucose in the prescence of glucose oxidase through determination of H₂O₂ producing during the process of the enzymatic catalytic reaction. In the presence of glucose oxidase, the color and the phosphorescence intensity change of nano TiO2/SiO₂ composite oxides also took place when different concentrations of glucose solution were added.Using this H₂O₂ sensor, we can determinate the the H₂O₂ concentration in two commercial samples. Satisfactory agreement between the proposed method and titrimetric method was obtained and the relative standard deviation (R.S.D) was less than 7.0 % for each sample. The results indicate that the sensor is suitable for the determination of H₂O₂ real samples.The electrochemiluminescence (ECL) based on solid-state Ruthenium (II) complexes ([Ru(dpp)₃][(4-Clph)₄B]₂) on indium-doped tin oxide (ITO) electrode is also described here. The proposed method used simple method to immobilize [Ru(dpp)₃][(4-Clph)₄B]₂ on ITO electrode and [Ru(dpp)₃][(4-Clph)₄B]₂ can obtain strong and stable ECL signals using oxalate as the co-reactant. The ECL could be observed with naked eye in dark room. Moreover, [Ru(dpp)₃][(4-Clph)₄B]₂ was not dissolve in aqueous solution and will not cause leaching from the ITO electrode,so it can be used reproducibly. Further more, we found the obvious inhibition of [Ru(dpp)₃][(4-Clph)₄B]₂ ECL by the very low phenol concentration (2.0×10-8 mol/L), so it has the potential possibility to determine lower concentration of phenolic compounds.