Catalytic kinetic determination of ultratrace amounts of silver with spectrophotometric detection

Silver has a very strong catalytic effect on the peroxodisulphate oxidation of Brilliant Cresyl Blue in the presence of 1,10-Phenanthroline as an activator. the reaction was followed spectrophotometrically by measuring the rate of change in absorbance of brilliant cresyl blue at 635 nm and 30 degrees C. Silver can be determined in the range of 0.3 - 1500.0 ng/ml by a fixed time method. The limit of detection is about 0.1 ng/ml of silver. Silver in real samples was determined with satisfactory results.