The gas-chromatographic determination of selenium in steel with 4-chloro-1,2-diaminobenzene

Abstract

A simple and practical method is described for the determination of small amounts of selenium in steel. A diluted mixture of equal volumes of hydrochloric and nitric acids is used to dissolve the steel sample, the selenium is completely converted into the quadrivalent state in the presence of perchloric acid and the large amount of iron(III) is masked with phosphoric acid. No loss of selenium has been encountered when using this treatment. Selenium-(IV) reacts with 4-chloro-1,2-diaminobenzene to form 5-chloropiaselenol, which is extracted into toluene and determined by means of a gas chromatograph equipped with a thermal conductivity detector. When samples of 0·1 g are used, the standard deviation at the 0·1–0·3 per cent. of selenium level is 0·002–0·003 per cent.