Determination of chromium(VI) with screen-printed ex-situ bismuth film electrodes by adsorptive stripping voltammetry

Abstract

This work presents a fast and sensitive method, with an ex–situ bismuth film screen-printed carbon electrode (ex–situ Bi–SPCE), for the determination of Cr(VI) through adsorptive stripping voltammetry (AdSV) using Pyrogallol Red (PGR) ascomplexing agent. The method is based on the oxidation of PGR by Cr(VI) and posterior complexation with Cr(III). To obtaina sensitive and selective method, the effects of various parameters such as pH, ligand concentration of PGR (CPGR),accumulation potential, and accumulation time (Eacc, tacc) were optimized. The optimal conditions using Bi–SPCE preparedex–situ were pH 4.5 (0.01 molL^-1 acetic acid/acetate buffer), CPGR: 2.6 μmolL^-1, Eacc: - 0.70 V and tacc: 60 s. Peak current isproportional to Cr(VI) concentration over the range 0.23–12.0 μgL^-1, with a 3σ detection limit of 0.97 μgL^-1. The method wasvalidated by determining Cr(VI) in tap water spiked with Cr(VI) and Cr(III).