Abstract
For the determination of total nitrogen in lake waters, three methods were proposed by the Agency of Environment in 1982. Among these methods, a simplest method was an ultraviolet spectrophotometric method after digestion of sample water mixed with potassium peroxodisulfate and sodium hydroxide in an autoclave at 120°C for 30min.
However, serious interference by bromide ion is observed when this method is applied to the determination of nitrogen in sea water samples.
For overcoming the above drawback of the method, a new spectrophotometric method was proposed in this paper. Dilute sea water sample with equal amount of pure water and digest it according to the procedure proposed by the Agency of Environment. Measure the absorbances at 210nm and 220nm or at 215nm and 220nm. Calculate the total nitrogen concentration in the sample.
The proposed method was applied to the determination of total nitrogen in sea water samples collected in Osaka Bay. The results of the determination agreeded with the values obtained with the conventional spectrophotometric method using the N- (1-naphthyl) ethylenediamine reagent.
