水中痕量氨的显色法测定及干扰分析

Colorimetric determination of trace ammonia in aqueous solution and the analysis of its interferences

本文研究了靛酚蓝显色法测定水溶液中低浓度氨的线性范围、检出限以及常见催化剂中的金属离子对测定结果的影响,并提出了对强干扰离子的掩蔽方案。实验结果显示,靛酚蓝显色法测定水溶液中氨含量精确度高,可靠性强。其标准曲线的R^(2)=0.99934,线性范围为0.0322~0.32 mM,检出限为0.0105 mM。对来自西安科技大学临潼校区校内湖和曲江池实际水样的回收率实验结果分别为101.09%和95.91%,符合定量分析要求。常见离子的干扰实验发现大部分金属离子对氨的测定并不会造成干扰现象,而个别金属离子会对测定结果产生较大影响。为解决这一问题,文中在大量实验基础之上提出了干扰离子的掩蔽方案。通过合适的掩蔽方法,可以将所有干扰离子的影响降低到测定误差允许的范围内。结果显示,靛酚蓝显色法可以在常见干扰离子存在下对水中氨测定达到较好的测量精度,为常温常压下的光电催化合成氨催化剂评价提供参考。

This paper reported an indophenol blue coloration method to determined trace ammonia in aqueous solution.The linear range,detection limit and the influence of metal ions used in common catalysts on the determination results were observed in detail.According to the strong interference of some ions on the detection results,ionic masking approaches were proposed.The results show that the indophenol blue coloration method has high accuracy and reliability for determining ammonia in aquous solution.The R^(2) of standard curve was 0.99934,the linear range was 0.0322~0.32 mM and the detection limit was 0.0105 mM.The recovery of the ammonia in water samples from campus lake of XUST and Qujiang lake were 101.09%and 95.91%respectively,which meet the requirements of quantitative analysis.The interference experiment of common ions shows that most metal ions will not interfere with the determination of ammonia,while minor metal ions will have a serious disturbance on the determination results.In order to solve this problem,based on a large number of experiments,a masking scheme for interfering ions was established.By appropriate masking method,the effects of all interfering ions can be reduced to the allowable range of measurement error.The results show that the indophenol blue coloration method can achieve a proper test accuracy for determination of ammonia in aquous solution in the presence of common interfering ions,which provides a reference for the photoelectro catalytic synthesis of ammonia at room temperature and pressure.