NEW SPECTROPHOTOMETRIC METHOD FOR THE DETERMINATION OF TRACE AMOUNTS OF PALLADIUM

A simple, rapid, selective, and sensitive method for the spectrophotometric determination of palladium is developed based on the reaction of Pd(II) with 1-amino-4-hydroxyanthraquinone (AMHA). The reaction is carried out at pH 3.8 in 50% (v/v) ethanol-water medium. The molar absorptivity of the complexed ligand is 1.1 · 104 l mol-1 cm-1 at 620 nm. Calibration plots are linear up to 17 μg Pd cm-3. The optimum concentration range (Ringbom plot) is between 3-14.5 μg cm-3. The spectral study of the reaction in solutions containing equimolar concentrations or an excess of one component, in the pH range ∼ 0.3-6.5, indicate the possible complex transitions that occur in solution. Complete graphical and logarithmic analysis of the absorbance-pH graphs was performed to demonstrate and characterize the complexation equilibria in solution. Under the optimum conditions, palladium can be determined as the noncharged complex Pd(AMHA)2 in the presence of a large number of foreign ions. Interferences caused by zirconium(IV) could be masked with fluoride ions. © 1990 Springer-Verlag.