Spectrophotometric determination of hydrogen peroxide in water with peroxidase-catalyzed oxidation of potassium iodide and its applications to hydroxylamine-involved Fenton and Fenton-like systems

A spectrophotometric method for the rapid measurement of hydrogen peroxide (H2O2) in aqueous solutions was developed in this study. This method is based on a reaction catalyzed by peroxidase (POD) in which potassium iodide (KI) is oxidized to generate the stable yellow-colored I-3(-) within 15 s. The absorbance of the generated I-3(-) at both 350 nm and 400 nm had good linear relationships with H2O2 concentration in the range of 0-70 mM ( R-2 > 0.999) with sensitivities of 2.34 x 10(4) M-1 cm(-1) and 5.30 x 103 M-1 cm(-1) respectively. Meanwhile, through calculation, the detection limits of the proposed POD-KI method at 350 nm and 400 nm were 0.09 mu M and 0.33 mM, respectively. Even when the concentration of H2O2 was up to 350 mM, the absorbance of the generated I-3(-) at 350 nm did not decrease observably. The generated I-3(-) was found to be stable enough in ultrapure water, underground water, reservoir water and samples containing the strong reducing agent hydroxylamine. Moreover, the proposed POD-KI method was successfully used to analyze trace H2O2 in rainwater, and to monitor the change of H2O2 concentration in the Fenton, hydroxylamine/Fenton and hydroxylamine/Cu(II)/H2O2 systems. Overall, the POD-KI method could be adopted as a candidate method to determine H2O2 in Fenton and Fenton-like systems, and especially in those involving hydroxylamine. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

A spectrophotometric method based on the reaction catalyzed by peroxidase (POD) and potassium iodide (KI) was developed for rapid measurement of hydrogen peroxide (H2O2) in aqueous solutions. The method showed good linear relationship and stability in various water samples, making it suitable for trace H2O2 analysis in rainwater and monitoring H2O2 concentration in different systems.