Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

A method for determining indium in milligram samples of indium-doped crystals of bismuth telluride is described. The pH effect of the aqueous phase (V_aq = 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 (V_org = 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%.