Water Security Monitoring using Surface-Enhanced Raman Spectroscopy

Clean drinking water is a critical component of the United States infrastructure and is therefore a potential target for terrorists. In addition to physical attacks to the water network, like dams, pumping stations and pipelines, there must be vigilance to prevent the water itself from being fouled with toxic/hazardous chemicals. It is virtually impossible to protect every river, stream or lake that contributes to the nation’s drinking water supply; therefore rapid detection of a chemical/biological attack followed by rapid remediation is paramount. Many toxins are deadly at very low dosages (low ppb or less for chemical, 1-100 cts/mL for biologic), requiring sensitive and precise measurements. Immediate on-site identification and action precludes the transport of samples to a laboratory setting. This program will demonstrate a handheld sensor that could also be potentially used in-line. This sensor is based on Surface-enhanced Raman Spectroscopy (SERS); the ability of SERS to detect chemical warfare agents was demonstrated at EIC Laboratories during the Joint Services Agent Water Monitoring program. In the Phase I program, SERS detection of a wide variety of chemical warfare agent simulants and degradation products as well as several pesticides and other TICs was demonstrated. Unique identification of each analyte was shown and ROC curve analyses were performed on some agent simulants. The ROC curves demonstrate that SERS can detect the analytes of interest with a high degree of sensitivity and selectivity. The highly encouraging Phase I experiments performed showed very few false positives and very few false negatives. The Phase II program will engineer and fabricate a compact, full range high resolution totally automatable SERS spectrograph with sampling accessory for rapid (~60s) field identification and quantification of aqueous toxins. The throughput and stray light rejection abilities of the instrument will be defined as will the precision of the SERS sensors. An expanded library of TICs will be collects and ROC curves generated. The program will culminate with testing against a chemical warfare agent during the ETV option. The Phase I results are extremely encouraging and point to the possibility for a fieldable instrument that can rapidly identify and quantify chemical warfare agent or toxic industrial chemicals that have entered the water supply. Although developed for Homeland Security measures, this sensor can also be used to monitor cleanups of toxic spills or pesticide/fertilizer runoff from nearby farms. The sensor could also be extended to biological contaminations.