Sensitive and selective extraction-spectrophotometric determination of trace amounts of palladium(II) as a mixed complex with 2-(5-methyl-2-pyridylazo)-5-diethylaminophenol and bromide

Abstract

A sensitive, selective and reproducible, spectrophotometric method has been developed for the determination of trace amounts of palladium, based on the extraction of palladium as a mixed complex with 2-(5-methyl-2-pyridylazo)-5-diethylaminophenol and bromide ion from 0.1 M sulphuric acid into toluene. The mixed complex has an absorption maximum at 553 nm. The reagent blank was made negligible by back-extracting the excess of reagent with 1 M sulphuric acid. Relative standard deviations were 0.3–1.3%. Beer's law was obeyed in the concentration range 0.008–0.32 µg ml^–1 of Pd and the detection limit was 0.4 ng ml^–1 on a three times the standard deviation of the blank basis. High concentrations of foreign ions, with the exception of Au^III, Pt^II, V^V and W^VI, do not interfere with the determination. The proposed method was applied successfully to the determination of palladium in some alloy, catalyst and environmental samples.