Determination of Chromium(VI) with Screen-Printed Ex-Situ Bismuth Ffilm Electrodes by Adsorptive Stripping Voltammetry

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) as complexing agent. The method is based on the oxidation of PGR by Cr(VI) and posterior complexation with Cr(III). To obtain a 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 prepared ex-situ were pH 4.5 (0.01 mol L-1 acetic acid/acetate buffer), CPGR: 2.6 mu mol L-1, Eacc: -0.70 V and tacc: 60 s. Peak current is proportional to Cr(VI) concentration over the range 0.23-12.0 mu g L-1, with a 3 sigma detection limit of 0.97 mu g L-1. The method was validated by determining Cr(VI) in tap water spiked with Cr(VI) and Cr(III). image