Fig. 3. Square wave anodic stripping voltammograms for increasing levels of PbO, CdO and CuO in 1 ng/L steps (curves a–h) in the presence of 10 ng/L Bi2O3 along with the background response (black line). Accumulation potential and time are −1.1 V and 120 s, respectively. Also shown, the resulting calibration plot for PbO (A), CdO (B) and CuO (C). Other conditions are the same as those in Fig. 1A.