Spectrophotometric determination of silver with 2-(2-quinolylazo)-5-diethylaminoaniline

A new chromogenic reagent, 2-(2-quinolylazo)-5-diethylaminoaniline (QADEAA) was synthesized. A highly sensitive, selective and rapid method for the determination of silver based on the rapid reaction of silver (I) with QADEAA has been developed. In the presence of sodium citrate–sodium hydroxide buffer solution (pH 6.5) and sodium dodecyl sulfonate (SDS) medium, QADEAA reacts with silver to form a violet complex of molar ratio 1:2 (silver to QADEAA). The molar absorptivity of the complex is 1.39×105 l mol−1 cm−1 at 580 nm. Beerʹs law is obeyed in the range of 0.01–0.6 μg ml−1. The relative standard deviation for 11 replicate samples of 0.2 μg ml−1 is 1.67%. This method can be applied to the determination of silver in water with satisfactory results.