Abstract
A method for the determination of zinc in aluminum alloy by chelatometric titration after an extraction with TOPO-benzene was presented.
The sample was taken up with hydrochloric acid, hydrogen peroxide and ammonium difluoride. The acid concentration was adjusted to 1.53.0N, and ferric ion was reduced to ferrous by ascorbic acid. Zinc was extracted twice with 20 ml of benzene solution containing 0.1 M TOPO by 3 min. shaking. Zinc. in the organic layer was back-extracted with 20 ml of perchloric acid (1+15) by 1 min. shaking.
Ammonium fluoride and sodium thiosulfate were added to the back-extracted layer for masking, respectively, Al3+ and Cu2+. After the adjustment of pH with hexamine, zinc was titrated with 0.01M or 0.005M EDTA solution by using XO as an indicator. Zinc in aluminum alloy was determined in 45 min. with sufficient accuracy and reproducibility.
