Sensitive Gas Chromatography Detection of Nanomolar Hydroxylamine in Environmental Water by Fe(III) Oxidation

Abstract

Nanomolar concentrations of NH2OH in natural water sources were determined using an Fe 3+ oxidation method. A pH of 2.35-2.50 was used, which was adjusted by adding a chloroacetate buffer. Equal amounts (1.0 mL) of the chloroacetate solution and ferric chloride solution were added to the water sample (70 mL) to oxidize NH2OH to N2O. The resulting N2O in the sample water was then quantified by headspace analysis using a gas chromatograph with an electroncapture detector (ECD), where a limit of detection of 0.2 μgN L -1 (14 nmol L -1 ) was achieved.This method was successfully applied to samples of freshwater, brackish water, and seawater, and despite the various salinities no interfering substances were observed. Furthermore, NH2OH was successfully detected in samples collected from the Hii River and Lakes Shinji and Nakaumi (Shimane Prefecture, Japan). In addition, the proposed method was also applicable to samples rich in organic substance derived from phytoplankton.

Autotrophic Fe-Driven Biological Nitrogen Removal Technologies for Sustainable Wastewater Treatment

“…Generally, abiotic reactions play an essential role in the production of total N 2 O at pH values less than 5. To prevent excessive greenhouse gas emissions, short-cut nitrification reactors usually control pH at near-neutral conditions to reduce the release of N 2 O from abiotic reactions (Hikino et al, 2021).…”