Sorption-spectrophotometric method for the determination of Pd(II) in aqueous solutions

Abstract

The reaction of Pd(II) with 1,8-dihydroxy-2-(prazol-5-ylazo)-naphthalene- 3-6-disulphonic acid (PACA) sorbed onto Dowex 1-X8 ion-exchange resin was investigated with the aim of developing an absorption-spectrophotometric analytical method for the determination of low Pd(II) concentrations in water. The immobilized reagent formed a 1:1 complex with Pd(II) having an absorption maximum at 650 nm. Parameters, such as pH, wavelength and contact time were optimised for a liven amount of the sorbed reagent. The linearity range of absorbance vs. Pd(II) concentration extended from 5x10(-6)- 5x 10(-5) M, 5x 10(-7) - 5x10(-6) and 2.5x 10(-8)-2.5x10(-7) M when using 10, 100 and 200 ml of sample solution. respectively. With a 200 ml sample, the detection limit was 2.5x10(-7) M Pd(II). Most metals, except Cu(II). did not interfere when present in tip to 100 times the concentration of Pd(II).