A Facile, Nonreactive Hydrogen Peroxide (H₂O₂) Detection Method Enabled by Ion Chromatography with UV Detector

Hydrogen peroxide (H₂O₂) is ubiquitous in the natural environment, and it is now widely used for pollutant control in water and wastewater treatment processes. However, current analytical methods for H₂O₂ inevitably require reactions between H₂O₂ and other reactants to yield signals and are thus likely subjective to the interferences of coexisting colored, oxidative, and reductive compounds. In order to overcome these barriers, we herein for the first time propose to analyze H₂O₂ by ion chromatography (IC) using an ultraviolet (UV) detector. The proposal is based on two principles: first, that H₂O₂ can deprotonate to hydroperoxyl ion (HO₂^-) when eluent pH is higher than the acid-dissociation coefficient of H₂O₂ (pK_a = 11.6); and second, that after separation from other compounds via IC column, H₂O₂ can be quantified by a UV detector. Under favorable operating conditions, this method has successfully achieved acceptable recoveries (>91%) of H₂O₂ dosed to ultrapure and natural waters, a calibration curve with R² > 0.99 for a wide range of H₂O₂ concentrations from 0.1 to 50 mg/L and a method detection limit of 0.027 mg/L. In addition, this approach was shown to be capable of distinguishing H₂O₂ from anions (e.g., fluoride and chloride) and organics (e.g., glycolate) and monochloramine, suggesting that it is insensitive to many neighboring compounds as long as they do not react quickly with H₂O₂. Hence, this study proves the combination of IC and UV detector a facile and reliable method for H₂O₂ measurement.