Separation of trace amounts of indium, gallium and aluminium from each other by cation-exchange chromatography on AG50-X4 resin

Traces and minor amounts of indium, gallium and aluminium can be separated from gram amounts of thallium and from each other by cation-exchange chromatography on a column containing as little as 2 g of AG50W-X4, a cation-exchange resin with low cross-linking. An elution sequence of 0.1 M HBr in 40% acetone [for Tl(III)], 0.2 M HBr in 80% acetone for In, 0.3 M HCl in 90% acetone for Ga and 3 M aqueous HCl for Al is used. The separations are very sharp and even 10-μg amounts of In, Ga and Al in synthetic mixtures are recovered quantitatively, with a standard deviation of 0.3 μg. The separation factors between neighbouring ions are extremely large (> 5000).