Nessler Colorimetric Determination of Ammonia-Nitrogen in Surface Water with Full Automatic Batch Chemical Analyzer

In a basic medium, a yellowish-brown compound (NH2Hg2OI) was formed by the reaction of ammonia nitrogen present as free ammonia or ammonium ion in water with K2HgI4, having its absorption maximum at 420 nm. Based on these facts, a full-automatic batch chemical analyzer for determination of ammonia-nitrogen in surface water was proposed. Linear relationship between values of absorbance and mass concentration of ammonia-nitrogen was kept in the range of 0.20-5.00 mg·L-1, with detection limit (3σ) of 0.020 mg·L-1. The proposed method was applied to the analysis of surface water, and the analytical results obtained by the present method was found to have no significant difference with those found by the GB method. Values of recovery obtained by standard addition method were found in the range of 95.5%-105%.