Determintaion of ammonia in seawater by flow injection

Based on the reaction that indophenol blue was produced by ammonia,sodium phenolate solution and sodium dichloroisocyanurate solution with the catalyst of sodium nitroferricyanide,a flow injection method was proposed for the detection of ammonia in seawater.The effect was studied.Linear relationship between the area of absorption peak and concentration of ammonia was obtained in the range of 10 ~1 000 μg/L,with a detection limit of 3 μg/L.The RSD was 1.3% of the 200 μg/L ammonia with seven continuous determinations.Using the Student's t-test at the 95% confidence level,the results of the proposed methods and the national standard method for three samples determination showed no significant difference.The recovery was in the range of 102.1% to 115.0% for the seawater samples.