Spectrophotometric determination of platinum after extraction of its phenanthraquinone monoximate into molten naphthalene

Platinum is determined spectrophotometrically after extraction of its phenanthraquinone monoximate into molten naphthalene in the pH range 2.8–4.1. Beer's law is obeyed in the concentration range 5.0–95.0 µg of platinum in 10 ml of chloroform solution at 425 nm. The molar absorptivity and Sandell's sensitivity are 1.755 × 104 l mol–1 cm–1 and 0.011 µg cm–2, respectively. Ten replicate analyses of a sample solution containing 50 µg of platinum gave a mean absorbance of 0.450 with a standard deviation of 0.0042 and a relative standard deviation of 0.93%. The interference from various ions has been studied and the method has been applied to the simultaneous determination of platinum and palladium in various synthetic mixtures.