Analytical applications of ternary complexes-VI Spectrophotometric determination of trace amounts of palladium

Extremely sensitive and specific colour reactions in both aqueous and organic solutions are described for the spectrophotometric determination of palladium(II) ions. The methods are based upon ternary complex formation with 1,10-phenanthroline or pyridine, and Rose Bengal Extra. Themolar absorptivities are 5 × 10⁴ (aqueous) and 1.25 × 10⁵ (organic) in the presence of a 1000-fold molar excess of EDTA as mass masking agent. Under these conditions there is negligible interference with the pyridine-Rose Bengal Extra system from the 22 cations (including silver, gold and platinum) and seven anions investigated. Both colour reactions take place within 15 min and the complexes are stable for long periods.