Modified spectrophotometry for micromolar H2O2 determination in iron-containing solutions with leuco crystal violet under both aerobic and anaerobic conditions†

Accurately quantifying hydrogen peroxide (H₂O₂) is essential for elucidating its role across diverse environments. Spectrophotometry is widely employed in laboratories for this purpose due to its convenience, cost-effectiveness, and low detection limits for micromolar H₂O₂ concentrations. However, accurate measurement of H₂O₂ in iron-containing solutions presents challenges due to the interference of iron ions. In this study, we propose a modified spectrophotometric method for H₂O₂ determination in iron-containing solutions by adding two types of iron ion chelators and selecting leuco crystal violet (LCV) as a chromogenic reagent due to its stability. By sequentially adding 1,10-phenanthroline and EDTA, and using a phosphate buffer at pH 4.2 to provide the optimal chromogenic pH condition, this modified method effectively mitigates the interference of iron ions in the LCV chromogenic reaction. The applicability of this method under aerobic and anaerobic conditions was confirmed by comparing the experimental results with theoretical simulations. Under optimal chromogenic conditions, this method achieves a detection limit of 300 nM. This improved method allows better detection of H₂O₂ in iron-containing systems and investigation of its significance in various environmental processes.