Abstract
A photometric determination of 0.00010.01% of tellurium in iron and steel with Bismuthiol II was investigated.
The tellurium-Bismuthiol II complex was extracted with chloroform, benzene and carbon tetrachloride from a 0.86N hydrochloric acid, sulfuric acid or perchloric acid solution.
This complex showed an absorption maximum at 335 mμ, and Beer's law obyed up to 50 μg of tellurium when 1 ml of Bismuthiol II solution (0.1%) was used.
The established method was as follows. A half gram of sample was decomposed in 30 ml of sulfuric acid (1+5) and was filtered through a filter paper.
The residue was dissolved in hydrochloric acid and hydrogen peroxide and boiled for 5 minutes. Tellurium was separated by precipitation as metallic tellurium together with arsenic added as a carrier by reducing with stannous chloride.
It was dissolved in nitric acid and perchloric acid and evaporated to vigorous fumes of perchloric acid. After cooling, 5 ml of hydrochloric acid (6N) and 1.0 ml of Bismuthiol II solution were added, and it was shaken for 30 sec. with 10.0 ml of carbon tetrachloride.
The organic layer was washed successively with the washing solution (dissolving 10 g of potassium phosphate, 17 g of sodium borate and 10 g of EDTA in water to make up to 1 litter) and the absorbance was measured at 335 mμ against carbon tetrachloride.
This method was very sensitive and simple, and the time required for an analysis was about 50 minutes
