Abstract
An extraction procedure with isopropylether is used for the separation of gallium from interfering elements, and gallium extracted was determined fluorometrically by reaction with 2-hydroxybenzaldehyde-thiosemicarbazone (HBTS). The analytical procedure was as follows: 0.1 g of a sample containing (0.00010.02) % of gallium was dissolved by heating in 5 ml of hydrochloric acid (2+1). To the solution obtained, were added 0.1 ml of 20 % titanium trichloride solution and 5 ml of hydrochloric acid (2+1). Then gallium in the solution was extracted twice with 5 ml each of isopropylether by shaking for 1 min. After the aqueous phase was removed, the organic phase was washed 5 times with 2 ml each of hydrochloric acid (2+1) by shaking for 15 s. The organic phase was evaporated to dryness on a water bath, and the residue was dissolved in 1 ml of hydrochloric acid (1+100) and diluted to 10 ml with water. To an aliquot containing (0.15.0) μg of gallium, were added 0.2 ml of 1 % L-ascorbic acid solution, 2 ml of HBTS solution in DMF (Ga>1.0μg: 0.05 % HBTS, Ga<1.0 μg: 0.01 % HBTS) and 0.5 ml of 2 w/v % ammonium acetate solution. The pH of the solution was adjusted to 4.5 with 0.1 N hydrochloric acid or 0.1 N ammonia water, and the solution was diluted to 25 ml with water. The fluorescence intensity of the solution was measured (λ excitation 365 nm, λ emission 440 nm). The analytical results obtained by the proposed method were in good agreement with those by spectrophotometric method using PAN (LIS AO5-1 1969). Accordingly, the proposed method could be applied to the determination of gallium above 0.0001 % in aluminum and aluminum alloys.
