Interference of dissolved organic matter and its constituents on the accurate determination of hydrogen peroxide in water

Jianbiao Peng,Shixiang Gao,Zhimin Gong,Xinan Wu,Jianhua Li,Mengjie Wang,Ya Zhang

doi:10.1038/s41598-021-01016-9

Abstract

Hydrogen peroxide (H2O2) is ubiquitous in natural waters, and plays an important role in both biological and chemical processes. This study investigated the influence of dissolved organic matter (DOM) and its substituents on the accurate measurement of H2O2 by peroxidase-mediated depletion of scopoletin fluorescence method which is one of the most widely used methods for the determination of low concentration H2O2 in water. Six DOM and its 24 substituents interfered the determination of H2O2 at environmentally relevant concentration of 200 nM with different levels except 2,6-dimethoxy-1,4-benzoquinone and benzoic acid, which may be associated with origin and types of DOM, and numbers and position of active functional groups in DOM constituents. Each substance concentration and the corresponding decreasing ratio to the measured H2O2 concentration was fitted well to the linear model (R2 > 0.9), and the obtained interfering ratios (k, (mgC L−1)−1), expressing the degree of DOM or its substituents per unit concentration to the measurement of H2O2, were approximate for DOM, but the order of magnitude of k values of DOM constituents took on a large span from 10–3 to 10–7. When DOM levels exceed 0.1 mgC L−1 or its substituent concentration is at nM level (low to 20 nM), the H2O2 content will be underestimated substantially. A quantitative structure–activity relationship model with remarkable stability and strong predictability for the k of DOM substituents to H2O2 measurement was established, and the k was related to the electron transfer capacity, hydrophobicity and stability of these compounds.

Highlights

Hydrogen peroxide (H2O2) is ubiquitous in natural waters, and plays an important role in both biological and chemical processes
In light of the diversity of specific dissolved organic matter (DOM) constituents (Fig. S1), 24 compounds with phenolic, carbonyl, carboxyl, and amino groups attached to benzene skeleton were selected; (2) to establish a quantitative structure–activity relationship (QSAR) model based on the data of interfering effect of DOM constituents on H2O2 concentration determination with good stability and prediction ability, thereby trying to predict the effect of other DOM constituent analogues on the H2O2 measurement in water
For each investigated DOM, it was apparent that DOM significantly interfere the accurate measurement of H2O2 content, and the measured concentrations were lower than the nominal concentration (200 nM)