Analytical Sciences

A Rapid and Sensitive Extractive Spectrophotometric Determination of Palladium(II) in Synthetic Mixtures and Hydrogenation Catalysts Using Pyridoxal-4-phenyl-3-thiosemicarbazone

L. S. SARMA,** J. R. KUMAR,* K. J. REDDY,* A. K. KUMAR,* and A. V. REDDY* 

*Analytical Division, Department of Chemistry, Sri Venkateswara University, Tirupati-517 502, A. P., India
**Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan

A rapid and sensitive extractive spectrophotometric method has been developed for the determination of palladium(II) in synthetic mixtures and hydrogenation catalysts using pyridoxal-4-phenyl-3-thiosemicarbazone (PPT) as an analytical reagent. The reagent forms a red-color complex with the metal at pH 3.0, which is extracted into benzene. The absorbance is measured at 460 nm. The method adheres to Beer's law up to a concentration range of 0.4 - 6.4 µg cm^-3. The molar absorptivity and Sandell's sensitivity are 2.20 x 10⁴ dm³mol^-1 cm^-1 and 4.85 x 10^-3 µg cm^-2, respectively. The correlation coefficient of the Pd(II)-PPT complex is 0.99, which indicates an excellent linearity between two variables. The detection limit of this method is 0.05 µg cm^-3. The instability constant of the Pd(II)-PPT complex calculated from Edmond and Birnbaum's method is 2.90 x 10^-5 and that of Asmus' method is 2.80 x 10^-5 at room temperature. The concurrent repetition of the method is checked and the relative standard deviation (RSD) (n = 5) was derived as 1.84 percent. The present method was applied to the determination of palladium(II) in synthetic mixtures and hydrogenation catalysts. The results were compared by employing an atomic-absorption spectrometer.

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