Flotation and spectrophotometric determination of silver with 4-(p-nitrophenylazo)-2-amino-3-pyridinol

A sensitive flotation-spectrophotometric method, based on the complex formed between Ag(I) and 4-(p-nitrophenylazo)-2-amino-3-pyridinol is described. The complex precipitates when the aqueous solution is shaken with benzene, and the solid formed is then dissolved in dimethylformamide. The molar absorptivity of the resulting solution is 10.7×104l·mole-1·cm-1 at 605 nm. Beer's law is obeyed between 0.08 and 1 ppm of silver. The molar ratio of Ag:reagent in the separated complex is 1:2. The effect of foreign ions has been determined and the proposed method can be applied to determination of silver in an exhausted photographic developing solution. © 1986 Springer-Verlag.