Determination of Chromium(VI) at Trace Level by Adsorptive Stripping Voltammetric

Abstract

A new method is proposed for the determination of Cr(VI) by differential pulse adsorptive stripping voltammetry using 4-(2-pyridylazo)resorcinol 100 nM and diethylenetriammine pentaacetic acid as complexing agents. The base electrolyte contains 100 nM 4-(2- pyridylazo)resorcinol and 0.625 M of NaNO₃ and 0.025 M of CH₃COONH₄ and 0.0125 M of diethylenetriammine pentaacetic acid, at pH = 6.2; under the optimum conditions. The peak current (Ip) is proportional to the concentration of Cr(VI) over the range 0.0288-6.00 nM. The lowest detected was 0.0481 nM. The relative standard deviation did not exceed ± 4.5 %. The method is highly selective and sensitive and has been applied to the determination of Cr(VI) in some vegetables.