Dual-wavelength dual-indicator catalytic spectrophotometric determination of trace silver

Objective:To establish a new dual-wavelength and dual-indicator catalytic kinetic spectrophotometric method for the determination of trace amount of silver.Methods:Silver(I) was determined by dual-wavelength and dual-indicator catalytic kinetic spectrophotometric method which was based on the silver(I) catalyzed oxidation of neutral red and methylene green by potassium persulfate in HAc-NaAc buffer medium(pH 4.5) and 2,2′-bipyridyl as activator.The absorbance of the catalytic and uncatalytic systems were measured at 440 nm and 660 nm.Results:The linear range of determination was 0.00500~0.0500 μg/ml.The detection limit was 1.4×10-10 g/ml.Conclusion:The method is simple and of high sensitivity and good selectivity.It can be applied to the determination of silver in waster water.