Square wave anodic stripping voltammetric determination of Hg(II) with N-p- chlorophenylcinnamohydroxamic acid modified carbon paste electrode

摘要

A new method has been developed for the electrochemical determination of Hg(II) with N-p-chlorophenylcinnamohydroxamic acid (CPCHA) modified carbon paste electrode by square wave anodic stripping voltammetry (SWASV). Hg(II) was accumulated on the electrode surface by the formation of the complex in an open circuit and the resulting surface was characterized by electrochemical reduction and stripping. The optimum voltammetric response was observed using a carbon paste composition of 7.5% (w/w) CPCHA and preconcentration time of 210 s in 0.1 M sodium acetate at pH 8 followed by electrochemical SWASV in 0.3 M NH4Cl solution at pH 4 at a reduction potential of -0.6 V. The voltammetric signals were linear in the range of 1-25 μM Hg(II) with a detection limit of 12.9 nM. The voltammetric response for six replicate measurements of 15 μM Hg(II) was reproduced with 3.8% relative standard deviation (RSD). Many coexisting metal ions had little or no effect on the determination of Hg(II). Five spiked samples of water were evaluated by using the developed method giving recoveries of Hg(II) in the range 98-105%.