Near-electrode pH change for voltammetric detection of insoluble lead carbonate

Abstract

Lead contamination of drinking water is a concern to all inhabitants of old cities where lead pipes and soldering are still present. Simple on-site electrochemical detection methods are promising technologies that have gained attention recently. However, conventional electrochemical techniques only quantify soluble forms of lead in water without accounting for insoluble particulates. Herein, a simple voltammetric technique for quantification of insoluble lead species is reported. Lead carbonate (PbCO₃) was used as a model compound to show the possibility of detecting particulate lead species directly in solution without chemical treatment. Specifically, electrochemical generation of protons was used as an alternative method to dissolve PbCO₃ and thus obtain a more realistic assessment of lead contamination. Lead was detected using cathodic stripping square wave voltammetry (CSSWV). After applying a high oxidizing potential to the electrode immersed in a PbCO₃ solution with solid PbCO₃ particulates, a significant increase in current was observed as compared to that of a saturated PbCO₃ solution. The signal was proportional to the amount of added PbCO₃, even when the solubility limit was exceeded. Thus, the combination of a local pH change with CSSWV provides a simple, rapid, and reagentless method for an in-situ detection of insoluble lead species.

Keywords: Cathodic stripping voltammetry; Electrochemical acidification; Lead detection; Lead particulates; Local pH change; Reagentless method.