Separation of bismuth from gram amounts of thallium and silver by cation-exchange chromatography in nitric acid

Abstract

Traces and small amounts of bismuth can be separated from gram amounts of thallium and silver by successively eluting these elements with 0.3 M and 0.6 M nitric acid from a column containing 13 ml (3 g) of AG50W-X4, a cation-exchanger (100–200 mesh particle size) with low cross-linking. Bismuth is retained and can be eluted with 0.2 M hydrobromic acid containing 20% v/v acetone, leaving many other trace elements absorbed. Elution of thallium is quite sharp, but silver shows a small amount of tailing (less than 1 gmg/ml silver in the eluate) when gram amounts are present, between 20 and 80 μg of silver appearing in the bismuth fraction. Relevant elution curves and results for the analysis of synthetic mixtures containing between 50 μg and 10 mg of bismuth and up to more than 1 g of thallium and silver are presented, as well as results for bismuth in a sample of thallium metal and in Merck thallium(I) carbonate. As little as 0.01 ppm of bismuth can be determined when the separation is combined with electrothermal atomic-absorption spectrometry.