MODIFICATION OF ELECTRODES WITH ADSORBED POLYAMINO ACIDS .1. CATHODIC STRIPPING VOLTAMMETRIC DETERMINATION OF COPPER(II) AT A HANGING MERCURY DROP ELECTRODE USING ADSORPTIVE ACCUMULATION ON AN ADSORBED LAYER OF POLY-L-HISTIDINE

The application of a hanging mercury drop electrode, modified by adsorption of poly-L-histidine, to the determination of Cu(II) in aqueous solutions has been studied. Selective and rapid pre-concentration of Cu(II) on the poly-L-histidine film was observed, even from dilute and quiescent solutions. Copper(II) was determined by differential-pulse adsorptive stripping voltammetry between 5 x 10(-9) and 4 x 10(-7) M after a 2-min accumulation time, using the reduction peak of its complex, a -0.4 V versus an Ag - AgCl reference electrode, obtained in acetate buffer solution of pH 4.5. No significant interference was observed from 1 x 10(-6) M levels of ethylenediaminetetraacetic acid, chromium(III), lead(II), nickel(II), cadmium(II) and manganese(II).