LINEAR SCAN STRIPPING VOLTAMMETRY OF COPPER(II) AT THE CHEMICALLY-MODIFIED CARBON-PASTE ELECTRODE

A new chemically modified electrode (CME), alpha-benzoinoxime (CUPRON) modified carbon paste electrode, for determining copper(II) is report ed because of its excellent selectivity and sensitivity. The electrode is made by mixing a quantity of CUPRON (25%, w/w) with graphite powde r (50%, w/w) and paraffin oil (25%, w/w). The CME preferentially depos its copper from the pH 8.5 NH3-NH4Cl buffer solution containing copper (II) under an open circuit and most of metal ions do not interfere wit h the measurements. The detection limit (S/N of three) for determining Cu(II) is 3 x 10(-10) g/ml after 10 min accumulation in fast linear s can stripping voltammetric measurement. Linear calibration curves are obtained for Cu(II) concentration ranged from 1 x 10(-8) M to 1 x 10(- 6) M. The response can be maintained with relative standard deviation of 6.0% in a 5 x 10(-6) M Cu(II) solution after eight accumulation/mea surement/regeneration cycles at the same electrode surface. The effect resulted from carbon paste preparation, reduction potential, electrod e renewal, electrolyte and solution pH, preconcentration time, concent ration dependence, possible interference and other variables has been evaluated. As for application, the CME demonstrates its high sensitivi ty and copper-selectivity in complex composition samples, such as anod ic mud and polluted water.