DEVELOPMENT OF A NEW ANALYTICAL METHODOLOGY BASED ON THE CATALYTIC EFFECT OF AG(I) IN A NEW FUCHSIN-PEROXODISULFATE-1,10-PHENANTROLINE SYSTEM: APPLICATION TO THE DETERMINATION OF TRACE AMOUNTS OF SILVER

摘要

A simple, rapid and sensitive kinetic spectrophotometric method is proposed for the determination of trace amounts of silver ion in the concentration ranges of 2-20 and 20-50 μg L-1. The proposed method is based on the catalytic effect of Ag(I) on the oxidation reaction of new fuchsin by potassium peroxodisulfate in the presence of 1,10-phenantroline as an activator at pH:5.0. The reaction is followed spectrophotometrically by measuring the change in absorbance at 547 nm using the initial rate method during the indicator reaction of 5 minute. The reaction rate variables like pH, reagent and activator concentrations and effect of reaction time and temperature were optimized in order to achieve the maximum analytical sensitivity. The experimental and theoretical detection limits of the developed method were found as 0.475 μg L-1 and 1.50 μg L-1, respectively. The relative standard deviations for five replicate measurements of 15 and 35 μg L-1 of Ag(I) were 5.27% and 3.32%, respectively. The effect of different diverse ions on the determination of silver was studied and found to be free from most interference. The method was successfully applied to the determination of silver in photographic solutions and different real water samples such as tap water, pond water and natural spring waters.