(521e) Simultaneous Analysis of Pb and Cd in Untreated Natural Waters with a Reusable, Microfabricated Anodic Stripping Voltammatry Chip

Real-time analysis of contaminants in natural and drinking waters is of great interest to the military in its unique role as both environmental steward and warfighter. Our laboratory is working to combine a series of microfluidic assays with a portable hardware platform to create a handheld water analysis system with user-selectable chemistry. Heavy metals are one of the most important classes of water contaminants due to their human and environmental toxicity. We have developed a heavy metal quantitation chip based on anodic stripping voltammetry (ASV) for the simultaneous determination of Pb and Cd in untreated natural and drinking waters. In our implementation, the sample stream is mixed on-chip with a bismuth-based reagent. This mixture is then electroplated onto a gold working electrode during the deposition stage of the ASV assay, creating an analyte-Bi alloy on the electrode surface. This deposition process allows significant concentration of rare analyte ions from solution onto the electrode, enabling limits of detection in the parts per billion range. Because each heavy metal species strips from the electrode surface at a unique potential, multiple analytes can be quantitated in a single run. After stripping analysis, the working electrode is maintained at a positive potential to regenerate the Au surface, allowing a single chip to be reused for multiple analyses. Results will be presented demonstrating analytical figures of merit for various heavy metal ions, the effects of water parameters on ASV results, and the effect of common interferants. Fluidic chip design considerations and fabrication strategies will also be discussed.