Accumulation and voltammetric measurement of silver at zeolite-containing carbon-paste electrodes

Silver-sensitive chemically modified electrodes are constructed by incorporating zeolites into a conventional carbon-paste mixture. Ion-exchange preconcentration is followed by medium-exchange to an electrolyte solution where the surface-bound silver is measured. The silver response is evaluated with respect to preconcentration time, electrode composition, silver concentration, pH, “cleaning” solution, possible interferences and other variables. Short preconcentration times permit convenient measurements down to the sub-mg l^?1 concentration level. The surface is renewed by placing the electrode in a sodium carbonate solution. For six accumulation/measurement/renewal cycles with a 1 mg l^?1 sample, the relative standard deviation was 3.9%. Similar measurements of mercury are also illustrated.