University Chemistry ›› 2019, Vol. 34 ›› Issue (3): 36-41.doi: 10.3866/PKU.DXHX201807034

• Chemistry Laboratory • Previous Articles     Next Articles

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

Jiamin WANG1,Han LI1,Wenkai ZHANG2,Chengshang LIU3,Baoliang LIU1,Huayu SUN1,Qikun ZHANG1,*()   

  1. 1 Chemical National Experimental Teaching Demonstration Center, College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Ji'nan 250014, P. R. China
    2 Handan No.1 High School, Handan 056001, Hebei Province, P. R. China
    3 Affiliated Secondary School of Shandong Normal University, Ji'nan 250014, P. R. China
  • Received:2018-07-26 Accepted:2018-08-19 Published:2019-03-09
  • Contact: Qikun ZHANG E-mail:zhangqk@sdnu.edu.cn
  • Supported by:
    山东师范大学本科生科研基金项目(2017BKSKY49);山东师范大学本科生科研基金项目(2018BKSKY54);大学生创新训练计划项目(20181501);山东师范大学教学改革项目:工程教育认证背景下化学工程与工艺专业建设与教学改革新探索

Abstract:

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.

Key words: Indophenol blue spectrophotometry, Nessler's reagent method, Colorimetric method, Ammonia nitrogen concentration, Absorbance

MSC2000: 

  • G64