ISO 601:1981

The sample is oxidized by nitric and sulphuric acids or by the use of Eschka mixture. Then, using the method specified in ISO 2590, the arsenic is reduced by zinc in sulphuric acid or hydrochloric acid medium. The arsine formed is absorbed in a solution of silver diethyldithiocarbamate in pyridine. The purplish-red colour produced by the colloidally dispersed silver is measured photometrically at the maximum of the adsorption curve (wavelength approximately 540 nm). Feste mineralische Brennstoffe; Bestimmung des Arsengehalts nach dem Standardverfahren von ISO 2590 mit Silberdiethyldithiocarbamat