Abstract
The complexometric method for gallium in Cu-(2040)% Nb-(16)% Ga alloys was developed. Sample was dissolved in nitric acid and hydrofluoric acid. After adding sulfuric acid, the solution was heated, evaporated to SO3 fume, and then cooled. The salts were dissolved in water, copper and niobium were precipitated by bromine water and sodium hydroxide. A small amount of dissolved niobium in the filtrate was masked by the mixture of 10 ml of 47 % hydrofluoric acid and 200 ml of saturated boric acid solution. After adjusting pH at33.5 by sodium acetate, gallium was titrated with EDTA at > 90°C using Cu-PAN as indicator. In the presence of niobium (<1 mg), copper and gallium was determined by back titration of excess EDTA with zinc (II) solution using Xylenol Orange involving the masking of copper with thiourea.
