气相分子吸收光谱法测定地下水中亚硝酸盐氮、氨氮、硝酸盐氮

采用气相分子吸收光谱法测定地下水中的亚硝酸盐氮(NO2^-)、氨氮(NH4^+)、硝酸盐氮(NO3^-)。考察NO2^-,NH4^+和NO3^-测定时的相互干扰,并给出了相应的消除方法。研究结果表明,测定NO2^-时,NH4^+和NO3^-无干扰;NO2^-对测定NH4^+和NO3^-产生干扰,可分别采用分段法和加入2滴10%氨基磺酸溶液的方法消除干扰;对于不含NO2^-或NO2-含量不高的地下水样品,可简化操作步骤直接测定NO3^-。该方法测定结果的相对标准偏差为0.73%~2.74%(n=12),样品加标回收率为97.67%~100.28%。所用检测仪器具有流动注射、自动进样及在线绘制标准曲线的功能,简化了标准方法中的样品前处理过程,减少了样品的损失,实现了自动化分析,大幅提高了检测结果的准确度和工作效率。

Determination of NO2-,NH4+,NO3- in groundwater samples by gas-phase molecular absorption spectroscopy

The contents of NO2^-,NH4^+ and NO3^- in groundwater samples were determined by gas-phase molecular absorption spectrometry.The interference among three ions was investigated and corresponding solved methods were given.The results demonstrated that the determination of NO2^-was not interfered by NH4^+ or NO3^-,and NO2^- affected the precise determination of NH4^+ and NO3^-.However,the interference could be respectively excluded by segment measurements and the addition of two drop of sulfamic acid solution with the mass faction of 10%.For groundwater without or with a small amount of NO2-,NO3-could be directly determined by simplifying the process.The relative standard deviation of the results was 0.73%-2.74%(n=12),and the recoveries of standard addition were 97.67%-100.28%.The detection instrument had the function of flow injection,online preparing standard curves,automatic addition of samples and analysis of the data,which simplified the treatment process of samples in the national standard methods,the loss of samples was decreased and the precision and efficiency were improved.