Polarography of palladium and indium at a dropping-mercury electrode with ε-caprolactam as a complexing agent

Abstract

The polarographic behaviour of palladium(II) and indium(III) has been studied using ε-caprolactam as the complexing agent at a constant ionic strength (0.1 M potassium nitrate). Well defined diffusion-controlled, irreversible waves were obtained for both metals. The forward rate constant (k⁰_f,h) and the transfer coefficient (nα) were calculated. The diffusion current constants were calculated to be 4.19 for palladium and 6.41 for indium, and were constant over wide concentration ranges of 1.0–3.0 and 1.0–3.5 mM, respectively. Based on the large difference in their E_1/2 values, a method is suggested for the simultaneous determinations of these metals when they are present together in pure solutions. The method has also been applied to the determination of these metals in some synthetic samples and certain alloys. The error did not exceed ±0.25% in any instance.