Separation of traces and larger amounts of bismuth from gram amounts of thallium, mercury, gold and platinum by cation-exchange chromatography on a macroporous resin.
Traces and larger amounts of bismuth (up to 50 mg) can be separated from gram amounts of thallium, mercury, gold and platinum (up to 5 g) by sorption from a mixture of 0.1M hydrochloric acid and 0.4M nitric acid on a column containing just 3 g (8.1 ml) of AGMP-50, a macroporous cation-exchange resin. This resin retains bismuth much more strongly than does the usual microporous resin (styrene-DVB with 8% cross-linkage). Other elements are eluted with the same acid mixture as that used for sorption, and bismuth is finally eluted with 1.0M hydrochloric acid. Separations of bismuth are sharp and recoveries quantitative. Only microgram amounts of the other elements remain in the bismuth fraction. Amounts of bismuth as little as 5 mug have been separated from 5 g of thallium, and determined (r.s.d. = 2%) by flame atomic-absorption. Only 100-mug amounts of bismuth have been separated from gram amounts of mercury, gold, and platinum, but there is no reason to believe that smaller or larger amounts of bismuth cannot be separated from these elements and recovered with the same accuracy as that for the separation from thallium. The lower limit of the method is determination of 0.4 mug of bismuth in 10 ml of solution (0.004 absorbance). An elution curve, the relevant distribution coefficients and the results of analysis of synthetic mixtures and two practical samples [thallium metal and mercury(II) nitrate] are presented.
Strelow
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Division of Processing and Chemical Manufacturing Technology, C.S.I.R., P.O. Box 395, Pretoria 0001, South Africa.