Extraction and spectrophotometric determination of Pd(II) with 3,4,4a,5-tetrahydro-3,3,4a-trimethyl-7-(substituted)-pyrimido(1,6-a)-benzimidazole-1-thiol (PBT).

A method for the extraction-spectrophotometric determination of palladium with 3,4,4a,5-tetrahydro-3,3,4a-trimethyl-7-(substituted)-pyrimido(1,6-a)benzimidazole-1-thiol (PBT) is described. PBT-Pd(II) complex is extracted from an acidic aqueous solution (0.01-0.5M HClO(4)) into a chloroform layer. The absorbance is measured at 438 nm and the molar absorptivity found to be 1.033 x 10(4)M(-1) cm(-1). The complex system conforms to Beer's law over the range 1.9-28.5 mug/ml palladium(II). The effects of pH (2-6), HClO(4) concentration, PBT concentration and shaking time were studied. The ratio of metal ion to ligand molecules in the coloured complex was found to be 1:4. The tolerance limit for many metals have been determined. Finally, the method has been applied successfully to the determination of palladium in synthetic mixtures and in the standard palladium carbon powder (palladium catalyst).