Evaluation of Solvents for Dissolution and Electrochemical Detection of Common Lead Forms in Test Drinking Water
Lead contamination in drinking water is a global human health concern. Total lead measurement requires lead dissolution of insoluble lead particles. Standard methods use extensive sample preparation and laboratory-based analysis, unfeasible for point-of-use sensors. Square wave stripping voltammetry using a bismuth-coated electrode has been proposed as a fast, safe, and accurate alternative to standard methods. However, point-of-use lead sensors are limited by a lack of lead dissolution. Lead dissolution of different lead forms in standardized test water with nitric acid at pH 2, hydrochloric acid at pH 2, and acetate buffer at pH 4.5 was investigated. Lead forms common in drinking water were tested and compared to lead nitrate, a form commonly used in laboratory-based studies. The lead dissolution solvents tested were used simultaneously as electrolyte solutions. Measurements were verified by inductively coupled plasma-mass spectrometry. Nitric acid and hydrochloric acid had comparable lead dissolution and sensing for lead forms common in drinking water and real tap water samples. The acids achieved low limits of detection, 1.38 μg l−1 in nitric acid, 6.06 μg l−1 in hydrochloric acid. We conclude nitric acid and hydrochloric acid have the potential to dissolve lead and act as an electrolyte for square wave stripping voltammetry sensing.
