Multiplexed Chemical Sensor for Water Security

The goal of this Phase II research project is to provide municipal authorities and the U.S. Environmental Protection Agency with a chemical sensor that can be multiplexed into water distribution systems to provide early warning of poisoned water supplies. This will be accomplished by developing surface-enhanced Raman (SER) sensors that can be integrated into water supply systems and coupled to a central Raman analyzer via fiber optics. All of the test chemicals, pesticides, chemical agent hydrolysis products, and cyanide were measured at the Phase I detection goal of 1 ppm (1 mg/L) within 5 minutes. The estimated limits of detection suggest that the Phase II detection goal of 10 ppb (0.01 mg/L or 0.01 ppm) can be obtained. Furthermore, in the case of cyanide, a 10 ppb flowing sample was detected in 1 minute. The overall goal of Phase II will be to fully develop the proposed analyzer and improve sensitivity to allow detection at 10 microorganisms/L in 10 minutes. (This meets or exceeds requirements for drinking water.) The project will include: ruggidizing the SER-active, sol-gel capillaries; developing a universal sampling system with a fiber optic probe interface; and developing comprehensive analysis that includes rapid chemical identification. Capabilities will be developed using real-world samples from a drinking water distribution system and water supply. An additional field test, performed at the U.S. Army’s Edgewood Chemical Biological Center, will involve the analysis of HD and VX (chemical agents) added to a close-loop water test system. In addition to the proposed application of monitoring water supplies to ensure safe drinking water, the proposed analyzer could be used by the military to ensure water safety of local supplies, and by first responders to assess safety of any water supply. Although the analyzer does not detect poisons, it will perform dual-use duty by monitoring traditional contaminants of concern (e.g., chlorinated organics generated by disinfection operations, cyanide by leaching operations, and chromium by plating operations).