Real-Time Multi-Parameter Analysis of Pollutants in Stormwater and Other Complex Analyte Matrices Using Electrospray Ionization-Ion Mobility Spectroscopy

The adverse effects of stormwater runoff on water quality in the United States have become an increasing concern in recent years. In 1996, the U.S. Environmental Protection Agency reported to Congress that urban runoff was the leading source of pollutants that cause water quality impairment related to human activities in ocean shoreline waters, and the second leading source of pollutants in estuaries across the Nation. Historically, the measurement of nutrients and priority pollutant compounds at trace levels in the complex sample matrices typical of stormwater discharges has required time-consuming and expensive offline measurement in laboratories equipped with sophisticated analytical instrumentation. This proposed innovative application of ion mobility spectroscopy (IMS), utilizing recent advances in electrospray ionization (ESI) techniques developed by project team members, will enable real-time aqueous phase field measurement of conventional parameters such as ammonia, phosphorus, nitrate, and nitrite, as well as a wide range of toxic organic and inorganic pollutants in stormwater, without the need for reagent additions or complex sample preparation. The objectives of dTEC Systems during this Phase I research project include determining the practical detection limits, range, response time, and reproducibility of measurement for chemical species representative of the most common urban stormwater pollutants using ESI-IMS. Additional objectives will be to evaluate the potential for interferences that might limit the applicability of the method for some analytes, and to assess the effectiveness of sample filtration and other inline sample pretreatment steps in maximizing the amount of chemical information that can be obtained using ESI-IMS. Completion of the Phase I objectives will make possible, during Phase II, the development and field testing of a working prototype ESI-IMS instrument for real-time monitoring of stormwater discharges and combined sewer overflows (CSOs). The ability to continuously monitor a wide range of inorganic and organic pollutants throughout the duration of a storm event would greatly improve the characterization of pollutant loads as well as the effectiveness of best management practices for stormwater treatment. With nearly 4,000 communities in the United States required to obtain permits for stormwater discharges, and 772 of these communities having CSOs with a total of 9,471 CSO discharges, the potential market for a cost-effective multianalyte instrument as proposed in this research is significant. Additional commercial opportunities that could be readily implemented include the monitoring of drinking water for arsenic and disinfection by-products and the monitoring of wastewater for conventional and priority pollutants.