New Methods For Determination Of Hydrogen Peroxide

Chapter 1 The study of determination of H2O2 with ion-selective electrode potentiometry and its application.SectionⅠThe oxidation-reduction association reaction system of KI?H2O2?Fe2+?MV was investigated and the electrode potential analysis characteristics were discussed. In the presence of PVA and pH 4.8 HAc?NaAc buffer solution, the ?OH formed by Fenton reaction ( Fe2+ as catalyst ) oxidized the excess I? into I3?. And the I3? combined with MV+ to form ion complex particle which result in the decrease of the free MV+ concentration of the system. The free MV+ concentrations were tracked by measuring the electrode potential of the reaction system using a homemade methyl violet ion-selective electrode. Based on the linear relationship between the changing intensity of electrode potential (ΔE) and the logarithm of concentration of H2O2 ( 22lg c HO) in solution, a new ion-selective electrode method for determination of H2O2 in water samples was establishmed.The experimental results showed that the enhanced electrode potential values (ΔE) of the system is proportional to the logarithm of concentration of H2O2 ( lg c H2O2) in the range of 0.068 ~ 0.816μg / mL on the optimum experimental conditions. The detection limit was 0.02μg / mL and the RSD was less than 4.3%. This method could be operated at normal temperature with high sensitivity and good selectivity and be used to determine the content of H2O2 in water samples with satisfactory results. The recoveries were 96.7% ~ 104.5%.SectionⅡThe free MG+ concentrations of the reaction system of KI?H2O2?Fe2+?MG were tracked by measuring the electrode potential using a self-made malachite green selective electrode as working electrode and the saturated calomel electrode as the reference electrode. The variation of the systerm's electrode potential was investigated. Based on the linear relationship between the change values of electrode potential (ΔE ) and the logarithms of H2O2 concentration in reaction solution under the appropriate conditions, a new potential analytical method for determination of H2O2 with the MG-ion selective electrode was established.The experiment results showed that the changing electrode potential values (ΔE ) of the reaction systems is proportional to the logarithms of concentration of H2O2 (lg c H2O2) in the range of 0.068 ~ 1.02μg / mL on the optimum experimental conditions, r=0.9973., the detection limit of 0.021μg / mL. This method was used to determine hydrogen peroxide in water samples with satisfactory results, the RSD was less than 3.81%, the recoveries were 97.2% ~ 104.3%.Chapter 2 The study on determination of H2O2 with new resonance light scattering system and its application.SectionⅠThe reaction system of KI?H2O2?Fe2+?CV was discovered and its resonance light scattering (RLS) spectra characteristics were studied. In the presence of PVA and pH 5.2 HAc?NaAc buffer solution, the ? OH formed by Fenton reaction ( with Fe2+ as catalyst ) oxidized the excess I? into I3?. And then the I3? combined with CV+ to form the ion complex particle which results in the enhancement of RLS of the system. Based on the linear relationship between the system's enhanced RLS intensity (ΔI ) and the concentration of H2O2 in reaction solution, a new RLS method for the determination of hydrogen peroxide ( H2O2 ) in water samples was established.On the optimum experimental conditions, the experiment results showed that the enhanced RLS intensity of the systems (ΔI ) is proportional to the concentration of the H2O2 in the range of 0.017-0.714μg/mL. The detection limit was 5.10×10-3μg / mL. This method was used to determine H2O2 in water samples with satisfactory results, the relative standard deviation was 3.1% ~ 3.5% , the recovery was 96.1% ~ 102%. SectionⅡThe oxidation-complex reaction system of KI?H2O2?Fe2+?MV was discovered and its RLS characteristics were studied. In pH 4.8 HAc-NaAc buffer solution, The ?OH formed by Fenton reaction could oxidize the excess I? into I3?, and then I3? combined with MV+ to form an ion association particle which results in the increment of RLS intensity of the reaction solution. The maximum RLS wavelength of the system was 568.0 nm. A new RLS method for determination of H2O2 in water samples was developed based on the proportional relationship between the changing intensity of system (ΔI) and the concentration of H2O2.The experimental results showed that there was the linear relationship between the increased resonance light scattering intensity (ΔI ) of the systems and the concentration of the H2O2 in the range of 0.034 ~ 0.680μg/mL. The detection limit was 1.02×10-2μg / mL. This method was used to determine H2O2 in water samples with satisfactory results,the RSD was less than 2.26%, the recoveries were 97.6~103.4%.