Browsing by Author "Rakowska, Magdalena I."
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Item Interlaboratory Study of Polyethylene and Polydimethylsiloxane Polymeric Samplers for Ex Situ Measurement of Freely-Dissolved Hydrophobic Organic Compounds in Sediment Porewater(Wiley, 2022-05-05) Lotufo, Guilherme R.; Michalsen, Mandy M.; Reible, Danny D.; Gschwend, Philip M.; Ghosh, Upal; Kennedy, Alan J.; Kerns, Kristen M.; Rakowska, Magdalena I.; Odetayo, Adesewa; MacFarlane, John K.; Yan, Songjing; Bokare, MandarThis study evaluated the precision and accuracy of multi-laboratory measurements for determining freely dissolved concentrations (C free) of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in sediment porewater (PW) using polydimethylsiloxane (PDMS) and low-density polyethylene (LDPE) polymeric samplers. Four laboratories exposed performance reference compound (PRC) pre-loaded polymers to actively mixed and static ex situ sediment for ~ 1 month; two laboratories had longer exposures (i.e., 2 and 3 months). For C free results, intra-laboratory precision was high for single compounds (CV ≤50%), and for most PAHs and PCBs interlaboratory variability was low (magnitude of difference ≤ factor 2) across polymers and exposure methods. Variability was higher for the most hydrophobic PAHs and PCBs, which were present at low concentrations and required larger PRC-based corrections, and for naphthalene, likely due to differential volatilization losses between laboratories. Overall, intra- and interlaboratory variability between methods (PDMS vs. LDPE, actively mixed vs. static exposures) was low. Results showed C free polymer equilibrium was achieved in ~ 1 month during active exposures, suggesting use of PRCs may be avoided for ex situ analysis using comparable active exposure; although such ex situ testing may not reflect field conditions. Polymer-derived C free concentrations for most PCBs and PAHs were on average within a factor of 2 compared to concentrations in isolated PW, which were directly measured by one laboratory; difference factors of up to 6 were observed for naphthalene and the most hydrophobic PAHs and PCBs. C free results were similar for academic and private sector laboratories. Demonstrated accuracy and precision for determination of C free using polymer sampling is anticipated to increase regulatory acceptance and confidence in method use.