CATHODIC STRIPPING VOLTAMMETRY DETERMINATION OF TRACE IRON WITH A CHEMICALLY-MODIFIED ELECTRODE

The utility of glass carbon electrode modified with Nafion for the cat hodic stripping voltammetic determination of iron (III) is demonstrate d. The method is based on the formation of the Fe(III) and alpha alpha -bipyridine complex, which is preconcentrated by a Nafion-modified ele ctrode at +0.75V (vs Ag-AgCl). A stripping scan is carried out from +0 .75 to -0.10 V at 100 mV/s scan rate. The favorable concentration of t he base solution contains 0.02 mol/liter LICl, 0.03 mol/liter HCL, and 1.0 x 10(-5) mol/liter alpha alpha-bipyridine (pH 2.5). Under the opt imal conditions, the peak current is proportional to Fe(III) concentra tion in the range of 0.05-2.0 ng/ml (2 min preconcentration time). The method has been used to determine iron in fountain water and longan w ith satisfactory results. (C) 1995 Academic Press, Inc.