Spectrophotometric determination of palladium after extraction with 3-hydroxy-2-methyl-1,4-naphthoquinone 4-oxime into molten naphthalene
A sensitive spectrophotometric method has been developed for the determination of palladium after extraction of its 3-hydroxy-2-methyl-1,4-naphthoquinone 4-oxime (HMNQO) complex into molten naphthalene. The optimum pH range for the extraction is 4.0–6.0. The solid naphthalene containing the palladium-HMNQO complex is separated by filtration and dissolved in N,N-dimethylformamide. The absorbance is measured at 485 nm against a reagent blank. Beer's law is obeyed in the concentration range 0.41–6.78 p.p.m. of palladium. The molar absorptivity and Sandell sensitivity are 1.86 × 104 l mol–1 cm–1 and 0.0056 µg cm–2, respectively. The interference of various ions has been studied in detail and conditions have been established for the determination of palladium in synthetic samples, alloys and catalysts.