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|Initiated: October 2001|
Team: Mike Siegal, Mike Kelly, Wayne Einfeld, Graham Yelton,|
Adam Rowen (grad student), David Muron, Carol Ashby
|Most chemical species that are currently regulated by the national water quality standards and other compounds, such as endocrine disrupters, that are under consideration for regulation are redox-active species that can be identified and quantified by electrochemical techniques. Standard microelectrodes and even commercial nanoband electrodes require the addition of extra chemicals to condition the water before analysis and are not useful for most real-time, in situ sampling. They require trained personnel and cannot be used either for distributed remote analysis in a water system or in a dipstick mode for on-site testing of drinking water. An array of suitably functionalized nanoelectrodes could be incorporated into a small, integrated sensor system that can identify many species rapidly and simultaneously under field conditions without chemical addition with S/N up to 1000-fold greater than conventional electrodes. We are investigating the use of functionalized carbon nanotubes as a sensor-array system for rapid, noncontaminating field analysis. The self-assembled template for these arrays will consist of conducting carbon nanotubes, whose diameter, length, and surface areal density can be systematically controlled.||
Chemical selectivity will be provided by chemical alteration of the carbon nanotube surfaces. Electrochemical deposition of a range of different metals to functionalize the nanotubes will produce different current/voltage relationships from electrode elements in the array as the analytes of interest are subjected to electrochemical analysis. Enhanced selectivity and sensitivity for specific metals, such as heavy metal industrial pollutants and radioactive nuclides, can be conferred by electrodeposition of thin organic conducting polymers containing functional groups, such as crown ethers, that selectively bind and preconcentrate the metals of interest for redox sampling. We will also develop organic-conducting polymers that can provide electrochemical signatures for organic and biochemical analytes that lack normal redox signatures, such as methyl tertiary butyl ether (MTBE) and halocarbons like trichloroethylene (TCE).
The goal of this project is to fabricate a prototype handheld device that can quantitatively measure arsenic concentration with ppb sensitivity.
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