VOLTAMMETRIC DETERMINATION OF CADMIUM ON A CARBON PASTE ELECTRODE MODIFIED WITH A CHELATING RESIN

A method is described for determination of cadmium using a carbon paste electrode modified with Amberlite IRC 718 chelating resin and voltammetric measurement of the collected ion. Optimal conditions for the preconcentration of cadmium were 10 minutes stirring at open circuit in 0.001 M ammonium buffer, pH 9. For electrochemical measurements, the optimal parameters include the use of a 0.1 M HCl solution, a delay time of 36 seconds at -1.1 V (vs. Ag/AgCl) and a 400 mV/s scan rate. The well-defined anodic peak at -0.7 V obtained is adequate for the quantitation of cadmium at very low concentration levels, with a detection limit of 0.005 mg/L. The method was used with good results for the determination of cadmium in polluted river waters.