RESUMO
A non-enzymatic fluorescence method for the determination of hydrogen peroxide (H2O2) was investigated. This method is based on the hydroxylation reaction of terephthalate (TP) by hydroxyl radical formed from reaction between H2O2 and Fe(II), resulting in the formation of a strongly fluorescent 2-hydroxyterephthalate (HTP). Under optimized conditions, a 3 nM detection limit and 1.0% precision at 200 nM were obtained. This was sensitive enough to determine the concentrations of H2O2 in coastal marine environments. The slopes of the calibration curve in seawater were nearly the same as those in Milli-Q water, suggesting that the fluorescent intensity was not affected by coexisting sea salts. However, the presence of nitrite at more than 10 µM interfered with the formation of HTP. The developed method was successfully applied to determine the concentrations of H2O2 in Osaka Bay on the research vessel. The results obtained in Osaka Bay demonstrated that H2O2 was photochemically produced via the photolysis of dissolved organic matter supplied from the river with fresh water at the surface layer.
