Optimization for the Determination of Hydrogen Peroxide in River Water Based on the Fenton Reaction with Terephthalate

Abstract

A non-enzymatic fluorescence method for the determination of hydrogen peroxide (H₂O₂) in river water samples was optimized to improve the reaction time and interference by coexisting nitrite. The method was based on the hydroxylation reaction of terephthalate (TP) by a hydroxyl radical formed from a reaction between H₂O₂ and Fe(II), resulting in the formation of a strongly fluorescent 2-hydroxyterephthalate (HTP). The concentration of Fe(II) strongly affected the reaction time and the signal intensity; the reaction time was shortened by increasing of Fe(II), while the signal intensities decreased with increase Fe(II). The addition of sodium sulfate in the reaction mixture reduced the interference of coexisting nitrite. Under the optimized conditions, a 3-5 nmol L⁻¹ detection limit and a 0.85 % precision at 300 nmol L⁻¹ H₂O₂ were obtained. The diurnal change of hydrogen peroxide was investigated at the Kurose River in Higashi-Hiroshima City, Hiroshima Prefecture. The concentrations of H₂O₂ were increased in the daytime. The maximum concentration of H₂O₂ was observed at 14 : 00, while the minimum was observed before sunrise.