The fluorometric determination of indium with 8-quinolinethiol

8-Quinolinethiol reacts with indium in the presence of acetic acid to give a yellow ternary complex. The complex, which has a greenish-yellow fluorescence with an emission maximum at 515 nm, can be extracted into chloroform at pH 2-4. In the ternary complex, the fluorescence intensity was about two times as large as that of the indium 8-quinolinethiolato complex containing no acetate ion. The fluorescence was stable for at least 1 h. By the use of a 0.2 μg/ml uranine solution as the setting reagent, 0-25 μg of indium in 10 ml of chloroform was determined. The coefficient of the variation was 3% for 12 μg of indium. The extractability of the ternary complex from 50 ml of an aqueous solution into 10 ml of chloroform was 99%. Iron, mercury, and silver, which interfere with the determination of indium, were masked with ascorbic acid, potassium iodide, and thiourea. Other interfering elements, including zinc, cadmium, gallium, nickel, palladium, cobalt, antimony, gold, copper, bismuth, and vanadium, must be removed before any analysis. (auth.)