ISO 10702:1993

Steel and iron — Determination of nitrogen content — Titrimetric method after distillation

The principle of the method specified is dissolving a test portion in hydrochloric acid followed by oxidation with hydrogen peroxide, fuming of the acid-insoluble residue in sulfuric acid with potassium sulfate and copper(II) sulfate, distilling the solution made alkaline with sodium hydroxide, collecting ammonia in a receiver containing orthoboric acid solution, titration of the ammonium ion with amidosulfuric acid. Is applicable to nitrogen contents from 0,002 % (m/m) to 0,5 % (m/m); does not apply to samples containing silicon nitride.