Abstract

A highly selective, reproducible and rapid spectrophotometric method for the determination of palladium (II) is developed based on the reaction of Pd (II) with 2,4-dihydroxyl acetophenone-p- hydroxylbenzoylhydrazone [RPPHBH] in the pH range 5 to 6 which forms a stable pale green complex. The complex shows absorbance maximum at 375 nm at pH of 5.5. Beer’s law is obeyed in the range 1.06 to 8.51 µg/ml of Pd (II). The molar absorptivity and Sandell’s sensitivity of the complex are 0.85 × 10⁴ L mol^–1cm^-1and 0.0126 µg cm^-2 respectively. Au (III) also reacts with RPPHBH at pH 5.5 to form a violet coloured complex. This complex shows an absorbance maximum at 590 nm. Thus, Pd (II) and Au (III) are simultaneously determined at pH of 5.5. The molar absorptivity of Pd (II) and Au (III) complexes of RPPHBH at 375 nm are 0.85 × 10⁴ L mol^–1 cm^-1 and 0.42 × 10⁴ L mol^–1 cm^-1 respectively. Pd (II): RPPHBH complex has no absorbance at 590 nm. The molar absorptivity of the gold complex at 590 nm is 0.5 × 10⁴ L mol^–1 cm^-1. This factis successfully exploited for the simultaneous determination of palladium (II) and Au (III) in alloys.

Key words: 2, 4–dihydroxylacetophenone–p-hydroxylbenzoylhydrazone (RPPHBH), palladium (II), Au (III), alloy samples, UV- Vis, spectrophotometry.