Electrochemical Measurement of Lead Levels in Drinking Water

Abstract

Many metal ions in water pose health and environmental hazards. Electrochemical measurements are simple, inexpensive, and reliable means to find the concentration of such metal ions in water, including lead. The Environmental Protection Agency (EPA) requires corrective action when lead concentrations in drinking water are greater than 15 ppb (7.24∗10−8 M). Even though clean water may be sent out from a central processing facility, there are still possible sources of contamination on the way to the faucet. Lead materials are in service which can corrode and introduce lead ions into residential drinking water. Underpotential deposition (UPD) is an electrochemical method which has been developed for measuring lead ion concentrations relevant to maintaining safe drinking water. UPD uses bonding interactions between a lead ion and electrode to reversibly form up to a monolayer of metal atoms on a surface at electrical potentials more positive than bulk lead reduction. The electrode coverage is proportional to lead ions in water. Gold metal is an electrode for measuring lead ions in water over wide ranges of pH and conductivities typically found in drinking water. When the gold electrode potential is scanned in the UPD potential region, a sharp current peak at a specific potential occurs for levels of lead up to and below 20 ppb in water. UPD offers a good alternative to stripping voltammetry for measuring the concentration of ions, like Pb2+, in water.