2.3. Apparatus
Cathodic–Anodic stripping voltammetric measurements were
carried out using a voltammeter VA 797 Computrace (Metrohm)
that was controlled by 797 PC Software (Version 1.2).
Measurements were carried out with a hanging mercury drop electrode
(HMDE), in a three-electrode arrangement. The auxiliary
electrode was a wire of platinum with a considerably larger surface
area than that of HMDE. A silver/silver chloride (KCl 3 M) was used
as a reference electrode. Stirring was carried out by a large Teflon
rod with 2000 rpm speed. Solutions were purged with high purity
nitrogen for 3.0 min prior to each experiment which was performed
under a nitrogen atmosphere. The instrumental conditions
for ASV and CSV have been summarized in Table 1. The pH values
of the buffer solutions were measured by a Metrohm pH meter
model 827