Figure 4From: Trace determination of cadmium in water using anodic stripping voltammetry at a carbon paste electrode modified with coconut shell powderElectrochemical impedance spectra of the carbon paste electrode. (a) Unmodified (curve a) and coconut shell powder-modified (curve b) CPE in potassium ferricyanide solution. (b) The circuit which most fitted to the unmodified CPE.Back to article page