氨氮分析时还原性物质的干扰去除研究

Research on Removing Interferences From Reducer During Ammoniac Nitrogen Detection

该文主要研究以下方面:(1)分析氨氮样品过程中发现用气相分子吸收光谱法时,在遇到Fe^(2+)等还原性物质的干扰时,会使测定结果偏低,加标回收率很低等现象。(2)提出解决方法,即络合保护氧化法。先用络合剂(铜离子)将氨氮络合隐蔽,加入强氧化剂(双氧水)消耗水体中的Fe^(2+)等还原性物质,再去除过量的氧化剂,最后上机分析氨氮浓度。采用此方法大大提高了氨氮的回收率,使准确度和精密度都得到满意的结果。实验表明,用铜离子络合,双氧水为氧化剂去除Fe^(2+)等还原性物质的干扰,此方法准确度高、重现性较好。使用此方法可满足对氨氮准确分析的需要,具有一定的推广意义。

Ammonia is one of the critical indicators to reflect the pollution extent of waterbody and eutrophication level of lakes and reservoirs.(1)Using Gas-Phase Molecular Absorption Spectrometry to analyze ammonia content,it was found that the presence of Fe^(2+) during sample analysis could result in a series of problems,such as a lower ammonia value and poor recovery rate.(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 Fe^(2+).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 Fe^(2+) and reducing matters such as ascorbic acid.This method is verified to be accurate and reproducible and consistent with the traditional methods.It is believed that using this method can satisfy the requirement for an accurate analysis of ammonia,and thus can be popularized in practice.