Solid Phase Extraction and Spectrophotometric Determination of Silver with 2-(2-Quinolylazo)-5-diethylaminoaniline as Chromogenic Reagent

 A new chromogenic reagent, 2-(2-quinolylazo)-5-diethylaminoaniline(QADEAA), was synthesized. A highly sensitive, selective and rapid method for the determination of silver was developed. It is based on the rapid reaction of silver (I) with QADEAA and the solid phase extraction of colored chelate using reversed-phase separation cartridge. At pH 6.5 in the presence of sodium dodecyl sulfonate (SDS), QADEAA reacts with silver to form a violet chelate in a molar ratio of 1:2 (silver to QADEAA). This chelate was enriched by solid phase extraction. The retained chelate can be eluted from the cartridge with ethanol. In ethanol medium, the molar absorptivity of the chelate is 1.36×105 L·mol−1·cm−1 at 590 nm. Beer’s law is obeyed in the range 0.01–0.6 µg L−1. The relative standard deviation for eleven replicate samples of 0.01 µg L−1 level is 1.9%. The detection limit reaches the 0.02 µg L−1 level. This method shows satisfactory results when used for the determination of silver in water.