Collect. Czech. Chem. Commun. 1988, 53, 3029-3039

Extraction-photometric determination of indium with 8-quinolinol in layered crystals of the type A2VB3VI

Jitka Šrámková, Stanislav Kotrlý and Yvona Kalischová

Department of Analytical Chemistry, Institute of Chemical Technology, 532 10 Pardubice


A method for determining indium in milligram samples of indium-doped crystals of bismuth telluride is described. The pH effect of the aqueous phase (Vaq = 40 ml) on the extraction yield is examined, also by considering the results computed with the data so far published. In a single extraction at pH 3·6-4·2 (acetate buffer) the tris(8-quinolinolato)indium(III) chelate is quantitatively transferred to the chloroform phase (Vorg = 10 ml). Bismuth present in excess is masked with thiosulfate. The absorbance of the chloroform extract is measured at 400 nm in a glass cell of 10-mm path-length (or in a 50-mm cell when m(In) < 20 μg). A blank extraction is carried out simultaneously with the use of a solution of pure Bi2Te3 and taken as reference. The calibration within the range of 10 - 130 μg of In(III) is performed by adding a standard indium(III) solution to the matrix solution obtained by dissolving pure Bi2Te3. The accuracy of the method has been checked by analysis of polycrystalline reference materials of known composition. The method is applicable for the analysis of milligram samples containing 0·6 - 5% of indium, with a relative standard deviation of 1 - 4%.