The formerly used X-ray contrast medium, Thorotrast—a colloidal thorium dioxide—causes a chronic exposure to α-particles. In this paper, a method for the colorimetric determination of thorium content in Thorotrast patient's organs is described. The sequential chemical separation of thorium has been studied on the basis of coprecipitation, ion exchange, and solvent extraction methods, followed by colonmetric analysis using Arsenazo III.
The experimental values were compared with those obtained by radiation measurement or neutron activation analysis of patient's organs.
