In the 1990s research on metal-sampling methods in natural waters (Benoit et al. 1997) demonstrated profound and systemic issues with previously accepted methods that invalidated decades of sampling results and led to the end of longstanding water-quality monitoring programs. The history of environmental sampling efforts for metals and other constituents has shown that the methods and materials used for collection, processing, and analysis of water-quality samples can substantially increase or attenuate measured concentrations (FHWA 2003; Horowitz 2013; Jiann et al. 2016). Decisions made about the sampling method, the materials used in sampling equipment, the filters, and other equipment used to process samples, and even the water, detergent, and preservatives used to clean equipment and preserve samples, can affect measured constituent concentrations. Laboratory intercomparison studies have demonstrated that when identical samples are provided to multiple laboratories for analysis of conventional constituents of interests, results from different laboratories can vary by orders of magnitude (FHWA 2003). Uncertainties for measured stormwater concentrations can be high, even for commonly monitored constituents such as sediment, phosphorus, and nitrogen (Harmel et al. 2006). Efforts to quantify the performance of stormwater treatment measures based on defensible data are critical because of the large life-cycle costs of stormwater management practices (Taylor et al. 2014). Research is needed to determine the methods and materials needed to obtain representative and unbiased concentrations of emerging contaminants in runoff, stormwater treatment system effluent, and receiving waters to support quantitative threat assessments and treatment decisions before large expenditures for monitoring data and treatment system construction are made.

The objective of this research is to evaluate the methods and materials used to collect, process, and analyze stormwater samples for determining concentrations of emerging contaminants such as Perfluoroalkyl and Polyfluoroalkyl Substances, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (6-PPD), 6PPD-quinone, and microplastics in stormwater runoff and stormwater treatment system effluent to establish robust sampling protocols and to establish the uncertainties and detection limits for emerging constituents of concern.