An electrochemical instrument for the analysis of heavy metals in water via anodic stripping coulometry for applications in remote sensing.

From the high levels of arsenic in groundwater in Bangladesh to the lead contamination of drinking water in Flint, Michigan, there are incidents across the globe that highlight the need for a reliable instrument capable of monitoring heavy metals remotely and continuously in a variety of geographical locations. Typical instrumentation for water analysis, such as ICP and AAS, must be housed in a central lab and relies on an operator traveling to the collection site, obtaining a sample, and transporting it back to the lab. This analysis provides a snapshot of the water quality that is limited to the specific time and location of collection. Portable instruments overcome delayed sample analysis time but still require a technician who must travel to the field to operate the equipment. Remote sensing overcomes these limitations as instruments are installed on-site and function autonomously to collect data continuously. This work is focused on developing an electrochemical technique featuring in situ background correction for applications in remote sensing of heavy metals in water. The technique is based on exhaustive anodic stripping coulometry in a fixed-volume cell and the target analytes are As(III) and Pb(II). Herein, the electrochemical device was redesigned to improve the detection limits for As(III) using double potential step-anodic stripping coulometry (DPS-ASC) to meet the WHO limit of 10 ppb. Stamp-and-stick fabrication was performed to define and control the sample volume. The gold electrode area was manipulated by fabrication of microelectrode arrays. The DPS-ASC technique was then optimized for the detection of Pb(II) in water using gold macroelectrodes and microelectrode arrays. Furthermore, the interference of Cu(II) was explored and managed by developing an in-line pre-electrolysis device. The practicality of DPS-ASC for analysis of real samples was evaluated using Ohio River water and the stability of the sensor was evaluated over the course of two weeks by daily analysis of Pb(II) charge. Last, novel boron doped diamond electrodes were evaluated for DPS-ASC analysis of Pb(II)