Removal Of The Interference By Reducing Matters During The Analysis Of Ammonia In Water Samples

Ammonia is one of the critical indicators to reflect the pollution extent of waterbody and eutrophication level of lakes and reservoirs. The accurate analysis of ammonia in waterbody is very paramount, in an effort to ensure human health, maintain the biological and toxicological indicator of waterbody, serve the government for the formulation of environmental protection regulations, standards and planning, and provide the relative data and materials for the full establishment of environmental protection and management.In this study, there are following research focuses:1.Using Gas-Phase Molecular Absorption Spectrometry to analyze ammonia content, it was found that the presence of Fe2+during sample analysis could result in a series of problems, such as a lower ammonia value and poor recovery rate. Inspired by the common solutions to sample analysis, we found that the dilution of samples could greatly improve the precision and accuracy. However, this method does not work well if ammonia content is extremely low.2. A new analytical method, called Complex Protection Oxidation Method, was applied. Complexing agent (copper ions) was used to complex ammonia, and then a strong oxidant (hydrogen peroxide) was added to consume Fe2+. Afterwards, excessive oxidant was removed, following a determination of ammonia concentration. The employment of this method could greatly enhance the recovery rate of ammonia and thus satisfactory accuracy and precision were achieved.Experimental results showed that copper ion complexation and the employment of hydrogen peroxide as the oxidant could remove the interference by Fe2+and reducing matters such as ascorbic acid. This method is verified to be accurate and reproducible, and consistent with the traditional methods. In addition, the application by other complexing agents and oxidants is not ideal, which means that using copper ion as a complexing agent and hydrogen peroxide as an oxidant can achieve the best removal effect of the interference by reducing matters. It is believed that using this method can satisfy the requirement for an accurate analysis of ammonia, and thus can be popularized in practice.