Alexander Sweett will present the poster “Validation of rare congener PCB Performance Reference Compound (PRC) method for equilibrium concentration determination of hydrophobic organic chemicals in sediment porewater” at the Society of Environmental Toxicology and Chemistry (SETAC) North America Annual Meeting at 8 a.m. on Monday, November 13, 2023. SiREM’s Kela Ashworth will also attend the conference, which runs from November 12 to 16 at Kentucky International Convention Center in Louisville, Kentucky.

Alexander’s coauthors are Geosyntec’s Jay Thompson and Jason Conder; US Army Engineer Research and Development Center’s Guilherme R. Lotufo; Eurofins Environment Testing America’s Andrew Patterson, Patricia McIsaac, and Robert Mitzel; and the University of Waterloo’s Faten Salim.

Alexander is a Chemistry Technician in SiREM’s environmental lab, where he focuses on passive samplers. He graduated from University of Guelph with a degree in chemistry, where he gained knowledge on computational research, environmental, and analytical chemistry.

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Passive sampling devices (PSDs) have been shown to present many advantages over conventional sampling methods for quantifying the freely available concentration (Cfree) of hydrophobic organic compounds (HOC) in sediment. Non-equilibrium correction protocols using PRCs have been developed for Cfree determination of HOCs during short-term field deployments. The inclusion of appropriate PRCs loaded into the PSD polymer prior to deployment allows the user to infer equilibrium concentrations through the application of mass transfer models. A common strategy for selecting PRCs is to use isotopically labelled compounds of the same compound class as the target HOC. The primary objective for this work was to validate non-equilibrium correction methods without the use of isotopically labelled PRCs. A series of ex situ laboratory experiments with test sediment were conducted using low density polyethylene (LDPE) PSDs spiked with two different classes of PRCs. In one set of test sediment, a standard suite of 10 rare congener PCB PRCs were used to quantify both the analyte uptake and PRC depletion for polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). A second test was spiked with 13C-labelled PCB PRCs to test if similar Cfree estimations are obtained with both sets of PRCs. The experiments demonstrated that the analyte uptake and rare PCB congener PRC elimination displayed similar kinetics, regardless of analyte class tested. Furthermore, similar PCB congener fingerprint and total PCB Cfree estimates were obtained using both 13C-labelled and rare congener PCB PRCs with 83% of Cfree for individual PCB congeners in agreement within a factor of 2 or less, suggesting that rare PCB congeners can be applied as a standard set of PRCs for Cfree determination. This hypothesis was further tested by “switching” the PRC results from an interlaboratory ex situ passive sampling study on PCBs and PAHs which ultimately results in similar Cfree estimation with 97% of the 70 measured Cfree values using labelled PAH PRCs for PAHs falling within a factor of 1.5 compared to those using labeled PCB PRCs and 88% of 76 measured Cfree using labeled PCBs for PCB congeners falling within a factor of 1.5 when using labeled PAHs PRCs. The overall effort of standardizing PRCs for PSD applications for multiple chemical classes further facilitates the wider acceptance and adoption of the technology.

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About the event: SETAC North America Annual Meeting

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