Highly Sensitive Adsorptive Stripping Voltammetric Method for the Ultra-trace Determination of Chromium(VI)

Abstract

A rapid differential pulse adsorptive stripping voltammetric method has been developed for the ultra-trace determination of chromium using 2,2′-bipyridine. The base electrolyte used is 0.1 M NH₄Cl (pH 6.0). The peak current was found to increase substantially with the addition of nitrite ions. A well-defined peak was observed at -1.3 V. Parameters, like concentration of the ligand, concentration of nitrite ion, accumulation potential, accumulation time, rest period, drop size, scan rate, pulse amplitude etc. have been optimized. Under the optimum conditions, the 3 σ detection limit was found to be 0.02 ppb (3.8 × 10^-10 M). The method is highly selective and sensitive, and has been applied to the determination of Cr(VI) in spiked water, effluents and ore samples.