Trace Level Quantification of Lead in Michigan Lake Water Using Differential Pulse Stripping Voltammetry: A Comparative Study on the Usage of Mercury Based Electrodes Vs Solid State Gold Electrodes

Abstract

The concentration of lead in fresh-water samples from the southern shoreline of Lake Michigan was analysed and compared using two different cell-stands: Controlled Growth Mercury Electrode (CGME) and voltammetry cell stand with disk type gold electrode. Clearly visible Lead (II) peaks at -395 mV and 130 mV were obtained with CGME and Au electrodes respectively using anodic stripping voltammetry (ASV) technique. Sensitivity, reproducibility, and ease of usage were differentiated for each method. While the measured lead concentration was 2.4 ppb using CGME set-up a closely similar concentration of 2.7 ppb was obtained with the gold disk electrode set-up and thereby confirms the availability of Hg-free detection of lead. The sensitivity obtained from the standard addition curve using the gold electrode was also over twice that of the CGME. The difference in background currents was attributed to the different electrode materials, bulk diffusion in electrolyte of lead ions, electrode-electrolyte interface and the relative surface areas of the electrode surface. Even after repeated polishing of gold electrodes in each run, its inherent sensitivity makes it an ideal candidate for lead determinations with no further requirement of handling the hazardous mercury wastes.