Due to their toxicity, even at low concentrations, lead and cadmium
are metals of prime environmental concern, but copper and
zinc are important as they may play a vital or a toxic role depending
on their concentration. For their determination, adsorptivestripping voltammetry (AdSV) is very suitable owing to its high
sensitivity, relative simplicity, no need for previous separation,
and because only very simple pretreatment of the sample is
required. One of the future trends in AdSV is multielement analysis.
AdSV requires the presence of a ligand with adsorptive properties
and the complexes must be formed quantitatively and quickly
in solution, they must be adsorbed on the electrode’s surface, and
later the ligand or the metal are oxidized or reduced [9–13]. Their
sensitivity and selectivity depends on the working electrode as
well as on the choice of a suitable ligand. Despite the toxicity of
mercury, the hanging mercury drop electrode (HMDE) is a nearly
ideal electrode, especially for cathodic processes and mainly due
to good adsorptive properties [14,15]. The sensitivity of the
method is directly related to the adsorption of the complex, and
the adsorption of the complex is related to its net charge, size,
and solubility. The favorable pharmacological effects of CQ are
probably related to its lipophilicity as well as to its ability to form
relatively stable complexes with Zn2+ and Cu2+ ions. Due to these
characteristics, CQ may be a good ligand which can be adsorbed
on a mercury electrode to determine these and other metal ions
at trace levels.
The aim of this study was to optimize the adsorptive stripping
voltammetry technique to determine Cu2+, Pb2+, Cd2+ and Zn2+
simultaneously using CQ as complexing and adsorbing agent.
Neither the use of this ligand in AdSV with analytical purposes
nor the simultaneous determination of some trace metals have
been reported yet