The need of the electrochemical activation procedure using SPGE is clearly demonstrated by comparing the square wave anodic stripping voltammogram of 50 ng mL−1 of mercury in 0.1 M of HCl obtained before and after activation by five cycles of cyclic voltammetry (CV) [15], using the
following conditions: potential range 0/+0.7 V, scan rate 50 mV s−1 (Fig. 1).