Color reaction of 2-(2-quinolylazo)-5-dimethylaminoanline with palladium and its application

Abstract

A new chromogenic reagent, 2-(2-quinolylazo)-5-dimethylaminoaniline (QADMAA) was synthesized. A sensitive, selective and rapid method for the determination of palladium based on the rapid reaction of palladium(II) with QADMAA was developed. In the presence of 0.5-2.5 mol $L^{-1}$ of hydrochloric acid solution and cetyl trimethylammonium bromide medium QADMAA reacts with palladium to form a violet complex with a molar ratio of 1:2 (palladium to QADMAA). The molar absorptivity of the chelate is 1.35x$10^5 L mol^{-1} cm^{-1}$ at 600 nm. Beer's law is obeyed in the range of 0.01 to 0.6 $mu g$ $mL^{-1}$. The detection limit is 1.2 $mu g$ $L^{-1}$. This method has been applied to the determination of palladium with good results.