Fast grey as a new indicator in titrations with EDTA

An acqueous solution of the Solochromate Fast Grey RA dye has proved a suitable indicator for the direct determination of thorium, ferric iron, bismuth and zinc, or the analysis of binary mixtures, thorium-iron, zinc-calcium, zinc-magnesium or zinc-thorium, with EDTA. Thorium can be determined in present of U, Fe, Zn, Ba, Be, Mg, and comparatively large amounts of rare carths. Ferric iron and zinc can be estimated in presence of U, Mg, Ca, Ba and Be. Cations of the rare and the alkaline carths can do not interfere with the determination of bismuth.