Selective extraction-spectrophotometric determination of microamounts of palladium in catalysts

A new thiosemicarbazone reagent, phthalaldehydic acid thiosemicarbazone (PA ATSC) has been synthesized, and found to he a good chromogenic reagent for palladium. A method for the extraction-spectrophotometric determination of palladium is described. PAATSC-Pd(II) yellow complex was extracted from an aqueous solution (pH 4, HAc/NaAc 2 mol l(-1)) into a MIBK layer. The absorb ance was measured at 355 nm and the apparent molar absorptivity (epsilon) w as found to he 5.1 x 10(4) l mol(-1) cm(-1). The effect of pH, PAATSC conce ntration and shaking time were studied. The complex system conforms to Beer 's law over the range 0.1 -2.0 mug ml(-1) palladium(II). The detection limi t was 23 ng ml(-1). The: tolerance limit for many metals has been determine d. The method is simple and rapid, with high sensitivity and good selectivi ty. Finally, the method has been applied successfully to the determination of palladium in synthetic mixtures and in the palladium-activated charcoal, used as a catalyst.