Abstract
The optimum conditions for the color reaction were obtained as follows from preliminary studies (Figs.26):Nessler's reagent 4.08 ml, solution volume before addition of Nessler's reagent 22.60 ml, and reaction time at room temperature about 30 seconds. The determination of nitrogen in solution is automatically performed according to the predetermined program (Fig. 7), after manual injection of a sample solution to the reaction vessel. The solution is circulated through the circulating pipe consisting of a bubble remover, an absorbance measuring flow cell, an air blowing pipe and a drain valve, after addition of water and Nessler's reagent. After 40 seconds, the absorbance of the solution is measured at 430 nm. Then the solution is drained off and the vessel is completely washed with water. This automatic analysis is sensitive and rapid; less than 50 μg of nitrogen is determined in 2.5 minutes. It may be applied to the determination of trace amounts of nitrogen in steel samples, combined with an automatic distillation apparatus under development.
