Multiplexed Chemical Sensor for Water Security

The overall goal of this proposed program (through Phase III) is to provide the municipal water authorities and the EPA 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 chemical, the pesticides, the chemical agent hydrolysis products, and cyanide were measured at the Phase I detection goal of 1 ppm (1 mg/L) within 5 minutes! And the estimated limits-of-detection suggest that the Phase II detection goal of 10 ppb (0.01 mg/L or 0.01ppm) can be obtained. Furthermore, in the case of cyanide a 10 ppb flowing sample was detected in 1-min! The overall goal of Phase II will be to fully develop the proposed analyzer and improve sensitivity to allow detection at 10 microg/L in 10 min (meets or exceeds the requirements for drinking water). This 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 performing two field tests. One field test will involve the analysis to a food dye artificially added to a water supply, while the other field test, performed at the US Army¿s Edgewood Chem Bio Research Center, will involve the analysis of HD and VX added to a close-loop water test system. Potential applications: 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. While not detecting poisons, the analyzer will perform dual-use duty by monitoring traditional contaminants of concern (e.g., chlorinated organics generated by disinfection operations, cyanide of leaching operations, and chromium by plating operations).