规定方法的原理是将试验部分溶解在盐酸中，然后用过氧化氢氧化，用硫酸钾和硫酸铜（II）熏制酸不溶性残留物，用氢氧化钠蒸馏成碱性的溶液，在含有原硼酸溶液的接收器中收集氨，用氨基磺酸滴定铵离子。适用于从0002%（m/m）到0.5%（m/m）的氮含量；不适用于含有氮化硅的样品。

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.