Spectrophotometric determination of palladium after extraction with phenanthraquinone monoxime into molten naphthalene

Conditions have been developed for the spectrophotometric determination of palladium after extraction of its phenanthraquinone monoximate into molten naphthalene. Palladium reacts with this reagent to form a water-insoluble, coloured, thermally stable complex that can be extracted into molten naphthalene in the pH range 2.0–5.4. Solid naphthalene containing the palladium complex is separated by filtration and dissolved in chloroform and the absorbance of the solution is measured at 430 nm against the reagent blank. Beer's law is obeyed in the concentration range 4.0–37.0 µg of palladium in 10 ml of chloroform solution. The molar absorptivity and Sandell sensitivity are 2.072 × 104 l mol–1 cm–1 and 0.005 1 µg cm–2, respectively. The interference of various ions has been studied and the method has been applied to the determination of palladium in synthetic mixtures.