Kinetic-Photometric Determination of Silver(I)Based on its Catalytic Effect on Reaction Between Potassium Ferrocyanide and 2-Hydroxy-4-Methoxybenzophenone Thiosemicarbazone

摘要

A novel sensitive and selective kinetic photometric method for the determination of nanogram amounts of silver(I)has been proposed.A slow reaction of the brown-coloured complex between potassium ferricyanide and 2-hydroxy-4-Methoxybenzophenone thiosemicarbazone (HBMPTS)was catalysed by traces of silver(I)in the acidic medium.At the wavelength of 420 nm an increase of the absorbance of the brown-coloured solution occurred to be proportional to the added amount of Ag(I).The optimum conditions (reagent concentration,temperature,ferricyanide concentration for the maximum reaction rate)and the selectivity of the method in the presence of trace amounts of Ag(I)were evaluated.Beer's law was obeyed in the Ag(I)concentration range 4.0-130 ng mL~(-1).Detection limit,molar absorptivit,Sandell's sensitivity an relative standard deviation (n=10)of the method were found to be 0.87 ng mL~(-1),1.0X10~6 L mol~(-1)cm~(-1),0.106 ng cm~(-2)and 0.98%respectively.Interferences from various foreign ions were studied.The method was applied to the determination of silver in synthetic CCRMP reference ores and copper-based alloys.