Spectrophotometric Determination of Microamounts of Nitrogen in Iron and Steel with the Organic Solvent Extraction

Spectrophotometric Determination of Microamounts of Nitrogen in Iron and Steel with the Organic Solvent Extraction. A spectrophotometric determination of nitrogen with the organic solvent extraction was studied, and it was found that blue coloured compounds of nitrogen with phenol and sodium hypochlorite were completely extracted with isobutyl alcohol only by use of a salting-out reagent. Various conditions for the determination were also examined to decide the optimum condition. By applying the results obtained by the fundamental experiments, a procedure for the determination of nitrogen in iron and steel was established as follows: After the dissolution of the sample with hydrochloric acid, nitrogen is separated by the steam distillation procedure. The solution is neutralized with sodium hydroxide, to which phenol and sodium hypochlorite are added. 10 minutes later the solution is saturated with sodium chloride and the coloured compound is extracted with isobutyl alcohol. Nitrogen is determined by the measurement of absorbance of the isobutyl alcohol layer at 660 mμ. The method can be used successfully for the determination of up-to 0.2 μg nitrogen in iron and steel and requires about 20 minutes.