Spectrophotometric determination of Pd(II) and Ag (I) by using the organic reagent 2- [(2- carboxy -4- iodophenyl) azo] -4,5- diphenyl imidazole

Abstract

The organic reagent, 2- [(2- carboxy -4- iodophenyl) azo] -4,5- diphenyl imidazole
(CAPAI), was found to be sensitive and selective reagent for the spectrophotometric
determination of trace amounts of palladium and silver. Pd(II) and Ag (I) react with CAPAI in
basic medium to form green and orange complexes in molar ratio of 1:2 and 1:1 for
palladium and silver ions respectively. The maximum absorbance of the complexes are at 594
& 518 nm with molar absorptivity of 43294.2 L.mol-1.cm-1 and 32425.7 L.mol-1 . cm-1 for Pd
and Ag respectively. Beer’s law is obeyed in the concentrations range 0.01-0.9μg. ml-1 for
Pd(II), and (0.02-1) μg. ml-1 Ag(I), with detection limit (S/N = 3) 0.004 ppm for Pd(II) and
0.007 ppm for Ag(I). The most important interferences were due to Co2+, Ni2+, Cu2+, Zn2+,
Cd2+, Hg2+, were studied, and suitable masking agents were used. The method was
successfully applied to the determination of palladium and silver in analytical samples.