Detecting hydrogen peroxide reliably in water via ion chromatography: a method evaluation update and comparison in the presence of interfering components

Abstract

Hydrogen peroxide (H₂O₂) is an oxidant/additive widely used in water oxidation processes but not commonly detected due to lack of reliable analytical methods in faces of complex water matrixes. In this study, we made an evaluation update and compared the performances of a recently established analytical method, which uses ion chromatography (IC), with a conventional spectrophotometric method on detecting H₂O₂ under various water conditions. The results indicated that the IC method has a wider calibration scope (0.01–10.0 mg L⁻¹, R² ≥ 0.998), more consistent slopes (≤2.4% variation), and a lower method detection limit (2.1 μg L⁻¹) than the colorimetric method (0.03–10.0 mg L⁻¹, R² ≥ 0.987, ≤14.4% variation, and 16.4 μg L⁻¹). More importantly, the IC method was less subject to interferences from varying reaction time and dissolved oxygen, nitrite, ferric ions, and humic acid contents, thus demonstrating its superiority over the conventional colorimetric method in face of coexisting interferents. Although the IC method has certain drawbacks, such as inconvenience for field use, underestimation of data at pH ≥ 12.4, and IC column clogging by precipitative cations, they can generally be overcome by sample pretreatment and hand-held IC. Partially due to the formation of nitrite, the colorimetric method obtained higher H₂O₂ values than the IC method from a real tap water photolyzed by ultraviolet (UV), vacuum UV, and UV activated H₂O₂, thus highlighting the importance of choosing an appropriate method to obtain a reasonable trend. The evaluation and comparison of the two H₂O₂ analytical methods may help facilitate their applications in different operational and environmental conditions.