Adsorptive Voltammetric Measurement of Trace Level of Iron(III) with 4-(2-Pyridylazo) Resorcin

The polarographic behavior of the complex of iron-4- (2-pyridylazo) resorcin(PAR) was studied. In HAc- NaAc- EDTA buffer solution, the complex can be adsorped on a hanging mercury drop electrode giving a sensitive adsorptive complex reduction peak with a peak potential at -0.36V(vs. SCE). Optimum experimental conditions were found by the use of 0.08mol/L HAc, 0.06mol/L NaAc, 5.0 × 10 −3 mol/L EDTA and 1.0 × 10 −5 mol/L PAR. With preconcentration for 60s, the derivative peak height of the complex compound is linearly proportional to the concentration for Fe in the range from 1.0 × 10 −9 mol/L to 1.0 × 10 −7 mol/L. For a 2-min pre-concentration time, the detection limit found was 2.0 × 10 −10 mol/L. This method has high sensitivity and selectivity. It has been applied to the determination of trace iron in food and water samples without any pre-separation step.