RAPID KINETIC DETERMINATION OF SILVER(I), USING IN-CUVETTE MIXING ANDCOMPUTERIZED DATA-ACQUISITION

The determination of silver(I) based on its catalytic effect on the ox idation of indigo carmine with hexacyanoferrate(III) is described. The reaction is monitored spectrophotometrically by means of a home-made rapid system with computer data acquisition. The decrease in absorbanc e of indigo carmine at 612 nm, pH 6 and at a fixed concentration of he xacyanoferrate(III) and indigo carmine is proportional to the concentr ation of Ag(I). The acquired data based on the initial rate and fixed time are processed. Up to 100.0 mu g/ml of silver are determined. The limit of detection and average relative standard deviation are 0.13 mu g/ml and 1.9%, respectively. The effect of foreign ions on the determ ination of silver is also discussed. The proposed method is applied to the determination of Ag(I) in expired photographic film.