Spectrophotometric determination of bismuth in metallic tellurium

Abstract

A spectrophotometric determination of bismuth with dithizone by using magnesium ethylenediamine tetraacetate (Mg-EDTA) as a masking agent has been studied and it was applied to the determination of trace of bismuth in metallic tellurium.
In the proposed procedure, the sample was dissolved with aqua regia in 200 ml beaker and excess ammonia was added into the solution to clear. It was adjusted to pH 10 with 10 ml buffer solution in a 100 ml separating funnel. Before the funnel was shaken, 1 ml of 1% aqueous solution of potassium cyanide, 1 ml of 0.0025 M Mg-EDTA and 5 ml of 0.01% carbon tetrachloride solution of dithizone were added. The two layers were separated and the absorbance of carbon tetrachloride layer was measured at 495 mμ.
Provided that 3μg of bismuth was to be deter mined, 100μg of Pb, 25μg of Fe, Cu, Zn and Ni had no influence on the absorbance by the proposed method. For determination of bismuth in metallic tellurium, satisfactory results with the standard deviation 1.23% were obtained. The whole operation was achieved within 1 hour.