Abstract
The fundamental conditions of photometric determination of tellurium with thiourea in nitric acid solution were investigated and applied to the analysis of cast iron. Tellurium-thiourea complex showed strong absorption at the wave-length less than 400 mμ. Because thiourea itself also showed considerable absorption at less than 345 mμ the absorption at 350 mμ was suitable for the determination. The optimum concentration of nitric acid and thiourea was 6% and 8.5%, respectively. The coloration was completed in 2 minutes and was stable within 10 minutes, and also it obeyed Beer’s law in the range of 0.05 to 0.5 mg of tellurium in 50 mL for 1 cm cell. Preliminary separation of tellurium in the sample was made in 3 N hydrochloric acid solution using stannous chloride. The other elements in ordinary cast iron did not interfere.
