Determination of Hydrogen Peroxide in Water by Chemiluminescence Detection, (II): Theoretical Analysis of Luminol Chemiluminescence Processes

The authors previously developed a flow injection type hydrogen peroxide detection system based on chemical photoluminescence spectroscopy. This system has the lowest detectable limit of 0.3 ppb. The relationships between the hydrogen peroxide concentration and luminous intensity were expressed as a linear function and a quadratic function of the H 2 O 2 concentration. In the present study, the chemiluminescence processes were theoretically evaluated by analyzing the chain radical reactions to confirm the effect of major parameters on the chemiluminescent intensity and to understand the complex relationship between H 2 O 2 concentration and luminous intensity. Then delay in luminescence was empirically analyzed by calculating diffusion of chemical species in the sample water and mixed reagent solution. The calculated results showed dependencies of the chemiluminescent intensity on luminol concentration and pH of the mixed reagent were mainly determined by a balance between OH radical concentration and luminol concentration. Furthermore the presence of O 2 - radicals in the mixed reagent might explain the linear relation between chemiluminescent intensity and H 2 O 2 concentration at low values.