两种比色法检测水体中微量氨含量的比较研究

氨氮含量的高低是衡量湖泊和水库水体富营养化的指标之一,水体中的氮元素极易诱发水体富营养化。目前,国标中通过比色法来检测氨氮含量的方法主要有靛酚蓝分光光度法和纳氏试剂分光光度法。根据高等教育国家标准中对于培养大学生的创新实践、科研意识、实验动手能力的要求,依照检测水体中氨氮含量的国家标准,检测了济南市区内三大名泉(趵突泉、黑虎泉、五龙潭)、大明湖、聊城东昌湖以及天津海河的水体样品中的氨氮浓度,并把山东师范大学的生活自来水作为对比样品,比较了比色法检测水体中氨氮含量的两种检测方法的差异。更重要的是,学生从检测过程中的得失领悟到了采用比色法检测、分析样品的方法技巧。结果表明,通过不断地完善检测方案,两种方法的标准曲线相关系数均达到0.9999以上。在实验操作中,由于操作过程和操作手法的不同(例如显色剂浓度、标准溶液的取用技巧以及各溶剂混合之后放置时间的长短等),获得了不同的实验结果,对实验结果的异常现象出现的原因进行了分析,同时讨论了两种检测方法的不同。

Comparison of Two Colorimetric Methods for the Determination of Trace Ammonia in Water

The level of ammonia nitrogen source is one indicator of eutrophication of lakes and reservoirs. Currently, indigo phenol blue spectrophotometry and Nash reagent spectrophotometry have been adopted to detect the NH₃-N content in national standard of the People's Republic of China. To cultivate college students' innovative practice, scientific research consciousness and experimental hands-on ability, the ammonia nitrogen concentration in the water samples of three famous springs (Baotu Spring, Heihu spring, Wulong pool), Daming Lake, Dongchang Lake and Haihe river was tested. Taking the drinking water from Shandong Normal University for comparison, the differences between the two methods were studied. More importantly, the students learned from the success and failure in the testing process that they used the colorimetric method to detect and analyze samples. The correlation coefficients of the standard curves of the two methods reached up to 0.9999 through continuous improvement of the detection scheme. In the experimental operation, different experimental results have been obtained due to the variation of operation and manipulation (such as the concentration of chromogenic agent, the operation skill of the standard solution and the length of the time after the mixing of each solvent etc.). This paper analyzes the causes of the outlier in the experimental results, and discusses the difference of two detection methods.