Flotation-spectrophotometric determination of palladium with thiocyanate and Methylene Blue

Abstract

A sensitive and precise method for the determination of microgram amounts of palladium, based on the ion associate of the anionic palladium(II)-thiocyanate complex with Methylene Blue (MB), has been developed. The ion associate is floated with benzene and dissolved in acetone, and its molar absorptivity is found to be 1.7 × 10⁵ l mol^–1 cm^–1 at 660 nm. The formation of the ion associate takes place over a wide pH range (1–6). The method is selective; interfering metals include silver, platinum, ruthenium, molybdenum and tungsten. The composition of the ion associate has been established as [MB⁺]₂[Pd(SCN)₄^2–]. The proposed method has been applied to the determination of trace amounts of palladium in high-purity silver after its preliminary separation from the matrix as palladium dimethylglyoximate.