Abstract
Extraction behaviors of palladium and rhodium using oxine and 2-methyl oxine have been studied. As the result, methods for determining these metals have been established. The methods involve addition of reagent solution, adjusting pH, aging the complex formed, extraction with 10.0 ml of chloroform by shaking for 1 minute, and measurement of absorbance of the extract.
Palladium oxinate is quantitatively extracted in a pH range of 3 to 11 (λmax=435mμ, ε=7.15×103), and palladium 2-methyl oxinate 1.8 to 11.2 (λmax= 428 mμ, ε =7.50×103). Rhodium oxinate is quantitatively formed by standing it at 80°C for 40 minutes in the presence of acetate. The optimum pH range is 4.7 to 8.3 (λmax =426 mμ, ε =1.08 × 104). No quantitative extracting condition for rhodium 2-methyl oxinate was found. In all cases, the extract should be washed with sulfuric acid (3 to 4 N) to remove other metals.
Furthermore, a method for consecutive determination of palladium and rhodium was established by applying the fact that the extracted palladium was removed easily by shaking with hydrochloric acid (3.5 to 5 N) for 7 minutes, while rhodium remained in the organic phase. The interferences were examined in each case.
