Objectives To investigate the differences among continuous flow analysis, ion chromatography, and Nessler's reagent spectrophotometry in determining ammonia nitrogen in drinking water.

Methods The method of continuous flow analysis, ion chromatography, and Nessler's reagent spectrophotometry were respectively used to determine ammonia nitrogen in drinking water and were compared in terms of detection limit, precision, accuracy, and recovery rate of standard addition. An analysis of variance was used to analyze the determination result of water samples, and the Q-test was used for comparison between any two method.

Results Continuous flow analysis had a relative standard deviation (RSD) of 0.61% and a recovery rate of standard addition of 96.0%~97.5%; ion chromatography had a RSD of 0.41% and a recovery rate of standard addition of 97.7%~102.1%; Nessler's reagent spectrophotometry had a RSD of 2.6% and a recovery rate of standard addition of 93.3%~105.0%. The result showed that all three method met the requirement for laboratory quality control, and there was no significant difference in determination result (F=1.199, P>0.05).

Conclusions Compared with Nessler's reagent spectrophotometry, continuous flow analysis and ion chromatography are simple, convenient, and rapid without pollution and can be used for the determination of ammonia nitrogen in a large number of drinking water samples. Continuous flow analysis can simultaneously determine volatile phenol, anionic synthetic detergent, and cyanide in drinking water.