Polarographic determination of antimony in steels and cast irons

Abstract

A method for the determination of antimony in steels and cast irons is described.

Antimony, separated from the ferrous matrix by precipitation with manganese dioxide and re-dissolved in sulphuric acid, is reduced to the tervalent state with sulphurous acid. Examinations were carried out by means of a cathode-ray polarograph in a solution that was 4 per cent. v/v in sulphuric acid, 10 per cent. v/v in hydrochloric acid, 5 per cent. v/v in orthophosphoric acid and 0·1 per cent. w/v in gelatine. The proposed method is free of interferences from the most common alloying elements of steels and cast irons.

Copper at any concentration does not interfere in this method, but with molybdenum alloyed steels a second precipitation, with manganese dioxide as carrier, is required. Bismuth causes interference only if it is in excess with respect to the antimony.

The proposed method is suitable for the determination of antimony at concentrations down to 0·001 per cent.