中文摘要：

作者结合工作经验，评述了测定氨氮的四种国家标准的特点，采用少取水样量稀释之，可以提高测定浓度上限，也解决了氧化剂加量不足或盐度大的问题。因而，对高浓度的样品（0．5—50mg/L）可以用水杨酸法取代纳氏法，避免了后者汞的污染；对低浓度样品（〈0．5mg／L），可以用次溴酸盐法取代苯酚法，克服了后者反应太慢的缺点。QUAATRO连续流动分析仪是可以取代上述方法较好的仪器。

英文摘要：

According to practical experience, we evaluate the character of four GB methods about ammonia determination. We improve the determination limit and solve the problem of insufficient oxidant adjunction and high salinity affecting by diluting a small amount of sample. However, if the sample has a high ammonia concentration, salicylic acid method can be adopted instead of Nessler＇s method to avoid mercury pollution. If the sample has a low ammonia concentration, bromate method can be used to replace phenol method that will overcome the shortcoming of slow reaction speed of the latter. QUAATRO continuous flow analyzer is a better instrument that may be used to replace the above methods.