Determination of NH4+ in Environmental Water with Interfering Substances Using the Modified Nessler Method

Nitrogen is an essential element in the environment. If excess nitrogen including NH4+ is present in water, however, it can result in algae blooming and eventually the destruction of the aquatic ecosystem. Therefore, the determination of NH4+ in streams, lakes, and effluents of the treatment facilities has long been carried out. The Nessler method is the most common spectrophotometric method to measure NH4+ in water. However, the result of the method becomes inaccurate if there are interfering substances such as Cl-2, Cl-, hardness-causing compounds (e. g., Mg2+), and Fe2+ in target water samples. In this study, therefore, the traditional Nessler method has been modified to eliminate the effects of interfering substances; the so-called MS was added to water samples. In addition, the polyvinyl alcohol reagent as a dispersing agent was added to water samples to increase the sensitivity and reproducibility of the method. The modified method could successfully analyze NH4+ of water samples even with the interfering substance at high concentration.