Determination of iron in water samples by adsorptive stripping voltammetry with a bismuth film electrode in the presence of 1-(2-piridylazo)-2-naphthol

An adsorptive stripping voltammetry method for the determination of iron has been developed. The procedure is based on the adsorptive collection of a complex of iron with 1-(2-piridylazo)-2-naphthol (PAN) on a bismuth-coated glassy carbon electrode (BiFE). Factors affecting the stripping performance, such as pH, PAN concentration (CPAN), potential, accumulation time (Eads, tads), and interference by other ions were also studied. The optimum conditions were obtained in a 0.1 mol L−1 acetate buffer at pH 4.0, CPAN 5.0 μmol L−1, tads 60 s, Eads −400 mV, pulse height 4.0 mV, pulse amplitude 25 mV, and frequency 15 Hz. The detection limit was found to be 0.1 μg L−1 when a tads of 60 s was used, and the linear range was from 0.4 to 60.0 μg L−1. The proposed procedure was validated by determining of Fe(III) in CRM-MFD, QCS-19 and CRM-SW certified reference materials and applied in seawater samples with satisfactory results.