Abstract
A variation of the triphenylmethane dye method for the determination of thallium has been modified to be suitable for analysis of urine samples in a small laboratory. Thallium is oxidized to the thallic state by bromine water, and is reacted with methyl violet for the colorimetric measurement. A maximum of 200 μg thallium per liter was found in the urine of 21 exposed individuals. Urine of unexposed persons showed virtually no thallium.