Solid phase extraction and spectrophotometric determination of silver with 2-(2-quinolylazo)-5-dimethylaminophenol

A new chromogenic reagent, 2-(2-quinolylazo)-5-Diniethylanlinophenol (QADMAP) was synthesized, and a sensitive, selective, and rapid method was developed for the determination of the mu g/L level of silver ions. The method is based on the rapid reaction of silver(l) with QADMAP and the solid phase extraction of the colored chelate using a C-18 cartridge. The QADMAP reacts with Ag(I) in the presence of a citric acid-sodium hydroxide buffer solution (pH 5.0) and a sodium dodecyl sulfonate (SI)S) medium to form a violet chelate of molar ratio 1 :2 (silver to QADMAP). This chelate was enriched by solid phase extraction with C-18 cartridge, and the retained chelate was eluted from the cartridge using ethanol (with 1%( acetic acid). In the ethanol medium (with 1% acetic acid), the molar absorptivity of the chelate was 1.25 x 10(5) L mol(-1) cm(-1) at 584 nm. Beer's law was obeyed in the range 0.01-0.6 mu g/mL. The relative standard deviation for eleven replicate samples of 0.01 mu g/mL was 1.86%. The detection limit is 0.02 mu g/L in the original samples. The method was applied to the determination of mu g/L levels of silver ions in water with good results.