The application of redox and induced reactions to the determination of thallium(III) in the presence of thallium(I)

Summary A new method of the determination of thallic ions Tl(III)] in the presence of thallous Tl(I)] ones, based on the oxidizing properties of Tl(III) towards cysteine was proposed. Cysteine was employed as an initiator in the iodineazide reaction and the oxidized part of the initiator was eliminated from the induced reaction medium by the respective redox reaction; the reaction products do not affect the above reaction. The contents of thallic ions (50–500 ng) in the sample can be determined from the progress in the induced reaction by measuring the unreacted iodine. The relative experimental error of the determination does not exceed 6%.