Study on the dual-wavelength and dual-indicator catalytic kinetic spectrophotometry for determination of trace silver

A new dual-wavelength and dual-indicator catalytic kinetic spectrophotometric method for the determination of trace silver is studied. The method is based on the catalyzing effect of silver on discoloring reaction of methylene blue and methyl violet by oxidation of potassium persulfate in the presence of 2, 2'-dipyridyl and phenothrolile as activators and emulsifier OP as a solubilization agent in the buffer media of HAc-NaAc at pH3.5. The absorbances in catalytic and uncatalytic systems are measured at 660 nm and 590 nm. Under the optimum conditions, the linear range of determination of Ag (I) is 0.002-0.080 Mg/mL. The detection limit is 6.5 × 10-10 g/mL The method has been used to the determination of trace silver in fixing waste with relative standard deviation of 1.5% and recovery of 98.3%.