Direct and derivative spectrophotometric determination of palladium with 2-aminoacetophenone isonicotinoyl hydrazone (2-AAINH)

Department of Chemistry, Sri Krishnadevaraya University, Anantapur-515 003, Andhra Pradesh, India

Manuscript received 20 June 2005, revised 2 August 2006, accepted 2 August 2006

2-Aminoacetophenone isonicotinoyl hydrazone (2-AAINH) has been proposed as a sensitive and selective reagent for the spectrophotometric determination of palladium(u) in alloy samples. The palladium ion forms an intense orange red coloured soluble complex with l-aminoacetophenone isonicotinoyl hydrazone (2-AAINH) in the acidic pH medium. The orange red color of Pd^II-2-AAINH solution exhibits maximum absorbance at 500 nm in the pH range 3-5. Beer's law is obeyed in the range 0.30-3.00 μg/ml of Pd^II at pH 4.0. The molar absorptivity and Sandell's sensitivity of the colored solution are found to be 3.00 x 104 L mol^-1 cm^-1 and 0.0035 μg cm^-2 respectively. The absorbance is found to increase linearly with increase in concentration of Pd^II, which is corroborated by the calculated correlation coefficient value (0.9998). The effect of foreign ions absorbance of the colored solution has been studied. The composition of the complex is calculated as 1 : 2 {Pd^II-2-AAINH}. The first derivative spectrum shows a peak at 540 nm with a zero cross at 494 nm. The second derivative spectrum shows a maximum at 560 nm and a minimum at 500 nm with a zero cross at 537 nm. Thus, sensitive first and second derivative spectrophotometric methods for the determination of Pd^II are also proposed.