An inexpensive disposable vapor sensor, which can also be used for urinalysis, can provide rapid field monitoring of pesticide exposure. The sensor utilizes Surface-Enhanced Raman Spectroscopy (SERS) to detect chemicals, like pesticides, that adsorb strongly on roughened SERS substrates in the high parts-pre- trillion range. As the sensors are tuned to the analytes of interest, interferences from more concentrated chemicals are limited. An earlier research program provided reliable results for organophosphate (OP) and organochlorine (OC) pesticides. In that program, 50 OP and OC pesticides or metabolites were evaluated in the laboratory at the low ppb range, with acephate and methyl parathion detection at farmworker camps. In this program, we will fabricate an innovative SERS sensing element for the detection of triazine pesticides, such as atrazine, simazine and cyromazine. Sensors will be optimized by an azide loading to improve the electron density and yield strong hydrogen bonding with the triazine amine groups. This novel sensor is expected to detect triazines in concentrations of 1 ppb or less and withstand the temperature and humidity conditions encountered by farmworkers. The new sensor can be easily combined with our previous sensor to measure >75 pesticides or metabolites at a fraction of the cost of current analytical laboratory methods, thus providing the NIH (particularly the NIEHS Exposure Biology program) with a large data set on the daily exposure/ingestion of pesticides. This data will allow epidemiological studies and predictions of long-term health outcomes. Core technology concepts have been demonstrated. A previous program demonstrated organochlorine and organophosphate pesticides can be detected down as low as 100 ppt. EIC Laboratories has demonstrated in preliminary studies that an azide-coated SERS sensor is several orders of magnitude more sensitive to triazines than previous sensors. The Phase I program is designed to demonstrate detection of triazine pesticides and metabolites at the 1 ppb level, show an extended field lifetime and an increased sensitivity for direct readings of triazine pesticide metabolites.
This SBIR proposal develops a field analysis protocol for a novel Surface-enhanced Raman sensor for triazine pesticides (broadleaf weed killers) directly or as metabolites in the urine of high risk populations, such as farmworkers. The sensor can provide timely results at significantly lower cost than other current protocols, allowing more sampling of at-risk populations and creating a database for epidemiological studies and health outcome predictions. This sensor, coupled at negligible cost to an already developed sensor will detect >75 pesticides/metabolites and report results to the farmworkers within 24 h at <10% the cost of sending samples to an analytical laboratory that can have analysis lag times of >6 months.
