Nanomolar determination of hydrogen peroxide in coastal seawater based on the Fenton reaction with terephthalate

Abstract

A non-enzymatic fluorescence method for the determination of hydrogen peroxide (H 2 O 2 ) was investigated. This method is based on the hydroxylation reaction of terephthalate (TP) by hydroxyl radical formed from reaction between H 2 O 2 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 H 2 O 2 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 H 2 O 2 in Osaka Bay on the research vessel. The results obtained in Osaka Bay demonstrated that H 2 O 2 was photochemically produced via the photolysis of dissolved organic matter supplied from the river with fresh water at the surface layer.