DETERMINATION OF INDIUM IN BISMUTH INDIUM TELLURIDE MATERIALS BY ANODIC-STRIPPING VOLTAMMETRY - METHOD DEVELOPMENT

Differential-pulse anodic-stripping voltammetry with the use of a pen- type hanging mercury-drop electrode was investigated for the determina tion of indium as dopant in milligram samples of thermoelectric bismut h-telluride material. After dissolving a milligram sample in dilute HN O3, telluric acid present in a great excess was oxidized by H2O2 in am moniacal medium to the less interfering Te-(VI)). In contrast with the supporting electrolytes containing sulfuric, nitric, perchloric, and hydrochloric acid, respectively, a higher sensitivity was achieved wit h a citrate buffer (of pH 2.6-2.9). The calibration plot was linear up to a concentration of about 2 mu g In-(III) per 1 mt of the measured solution; the corresponing detection limit was 5.6 ng/mL (49 nmol/L). A standard bismuth telluride material containing 2.94% w./w. In was us ed to compare the results of the method with applications of flame ato mic absorption spectrometry, extraction spectrophotometry and scanning energy dispersive X-ray analysis.